ARTICLE | doi:10.20944/preprints202209.0450.v1
Subject: Biology And Life Sciences, Biophysics Keywords: Heslington brain; intrinsically disordered protein; intrinsically disordered region; binding-induced folding; disorder-to-order transition
Online: 29 September 2022 (03:49:27 CEST)
Proteomic analysis revealed the preservation of many proteins in the “Heslington brain” (which is at least 2,600-year-old brain tissue uncovered within the skull excavated in 2008 from a pit in Heslington, Yorkshire, England). Five of these proteins (“main proteins”), heavy, medium, and light neurofilament proteins (NFH, NFM, and NFL), glial fibrillary acidic protein (GFAP), and myelin basic (MBP) protein are engaged in the formation non-amyloid protein aggregates, such as intermediate filaments and myelin sheath. We used a wide spectrum of bioinformatics tools to evaluate the prevalence of functional disorder in several related sets of proteins, such as “main proteins” and their 44 interactors, as well as all other protein identified in the Heslington brain. These analyses revealed that all five “main proteins”, half of their interactors and almost one third of the Heslington brain proteins are expected to be mostly disordered. Furthermore, most of the remaining proteins are expected to contain sizable disordered regions. This is in contrary the expected substantial (if not complete) elimination of the disordered proteins from the Heslington brain. Therefore, it seems that the intrinsic disorder of NFH, NFM, NFL, GFAP, and MBP, their interactors and many other proteins might play a crucial role in preserving the Heslington brain by forming tightly folded brain protein aggregates, in which different parts are glued together via the disorder-to-order transitions.
ARTICLE | doi:10.20944/preprints202208.0531.v1
Subject: Biology And Life Sciences, Virology Keywords: Rabies; intrinsic disorder; intrinsically disordered protein; intrinsically disordered protein region; protein-protein interaction
Online: 31 August 2022 (03:47:31 CEST)
Rabies is a neurological disease that causes between 40,000 and 70,000 deaths every year. Once a rabies patient has become symptomatic, there is no effective treatment for the illness, and in unvaccinated individuals, the case-fatality rate of rabies is close to 100%. French scientists Louis Pasteur and Émile Roux developed the first vaccine for rabies in 1885. If administered before the virus reaches the brain, the modern rabies vaccine imparts long-lasting immunity to the virus and saves more than 250,000 people every year. However, the rabies virus can suppress the host’s immune response once it has entered the cells of the brain, making death likely. This study aims to make use of disorder-based proteomics and bioinformatics to determine the impact that intrinsically disordered protein regions (IDPRs) in the proteome of the rabies virus have on the infectivity and lethality of the disease. This study uses the proteome of Rabies Lyssavirus (RABV) strain Pasteur Vaccins (PV), one of the best understood strains due to its use in the first rabies vaccine, as a model. The study suggests that the high levels of intrinsic disorder in the phosphoprotein (P-protein) and nucleoprotein (N-protein) allow them to participate in creation of the Negri bodies and help this virus suppress the antiviral immune response in the host cells. Additionally, the study suggests that there is a link between disorder in the matrix (M) protein and the modulation of viral transcription. The disordered regions in the M protein have a possible role in initiating viral budding within the cell. Furthermore, we checked the prevalence of functional disorder in a set of 37 host proteins directly involved in the interaction with the RABV proteins. The hope is that these new insights will aid in the development of treatments for rabies that are effective after infection.
REVIEW | doi:10.20944/preprints202310.1723.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: molecular tweezers; cation-pi interactions; intrinsic disorder, protein-protein interactions; hydrophobic interaction chromatography, monoclonal antibody production; protein aggregation; protein refolding; arginine methyltransferases; post-translational modification
Online: 27 October 2023 (05:51:26 CEST)
Arginine shows Jekyll and Hyde behavior in several respects. It participates in protein folding via ionic and H-bonds and cation-pi interactions; the charge and hydrophobicity of its side chain makes it a disorder-promoting amino acid. Its methylation in histones; RNA binding proteins; chaperones regulates several cellular processes. The arginine-centric modifications are important in oncogenesis and as biomarkers in several cardiovascular diseases. The cross-links involving arginine in collagen and cornea are involved in pathogenesis of tissues but have also been useful in tissue engineering and wound-dressing materials. Arginine is a part of active site of several enzymes such as GTPases, peroxidases, and sulfotransferases. Its metabolic importance is obvious as it is involved in production of urea, NO, ornithine and citrulline. It can form unusual functional structures such as molecular tweezers in vitro and sprockets which engage DNA chains as part of histones in vivo. It has been used in design of cell-penetrating peptides as drugs. Arginine has been used as an excipient in both solid and injectable drug formulations; its role in suppressing opalescence due to liquid-liquid phase separation is particularly very promising. It has been known as a suppressor of protein aggregation during protein refolding. It has proved its usefulness in protein bioseparation processes like ion-exchange, hydrophobic and affinity chromatographies. Arginine is an amino acid, whose importance in biological sciences and biotechnology continues to grow in diverse ways.
REVIEW | doi:10.20944/preprints202301.0004.v1
Subject: Biology And Life Sciences, Biophysics Keywords: Baroenzymology; Cryoenzymology; Intrinsic disorder; Intrinsically disordered proteins; Macromolecular crowding; Nanomaterials; Partially folded intermediate; Protein denaturation; Protein engineering; Protein flexibility; Protein folding; Protein function; Protein stability; Protein structure; Protein refolding; Protein unfolding
Online: 3 January 2023 (06:48:30 CET)
Transition between the unfolded and native states of the ordered globular proteins is accompanied by accumulation of several intermediates, such as pre-molten globule, wet molten globule, and dry molten globule. Structurally equivalent conformations can serve as native functional states of intrinsically disordered proteins. This overview captures the characteristics and importance of these molten globules in both structured and intrinsically disordered proteins. It also discusses examples of engineered molten globules. The formation of these intermediates under the conditions of macromolecular crowding and their interactions with nanomaterials are also reviewed.
REVIEW | doi:10.20944/preprints202009.0076.v1
Subject: Medicine And Pharmacology, Pathology And Pathobiology Keywords: severe acute respiratory syndrome coronavirus 2; SARS-CoV-2; coronavirus disease 2019; COVID-19; viral infection; virus-host interaction
Online: 4 September 2020 (03:19:43 CEST)
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing pandemic of coronavirus disease 2019 (COVID-19). The worldwide transmission of COVID-19 from human to human is spreading like wildfire, affecting almost every country in the world. In the past 100 years, the globe did not face microbial pandemic similar in scale to COVID-19. Taken together, both previous outbreaks of other members of the coronavirus family (SARS-CoV and MERS-CoV) did not produce even 1% of the global harm already inflicted by COVID-19. There are also four other CoVs capable of infecting humans (HCoVs), which circulate continuously in the human population, but their phenotypes are generally mild, and these HCoVs received relatively little attention. These dramatic differences between infection with HCoVs, SARS-CoV, MERS-CoV, and SARS-CoV-2 raise many questions, such as: Why is COVID-19 transmitted so quickly? Is it due to the some specific features of the viral structure? Are there some specific human (host) factors? Are there some environmental factors? The aim of this review is to collect and concisely summaries the possible and logic answers to these questions.
HYPOTHESIS | doi:10.20944/preprints202308.0776.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: SARS-CoV-2; IgG4; Tregs; long COVID; immune tolerance
Online: 9 August 2023 (11:18:47 CEST)
SARS-CoV-2, the virus that causes theCOVID-19 disease, has been demonstrated to cause immune suppression in certain individuals. This can manifest as a reduced ability for the host's immune system to effectively control the infection. Studies have reported that patients with COVID-19 can exhibit a decline in white blood cell counts, including natural killer cells and T cells, which are integral components of the immune system's response to viral pathogens. These cells play critical roles in the immune response to viral infections, and their depletion can make it harder for the body to mount an effective defense against the virus. Additionally, the virus can also directly infect immune cells, further compromising their ability to function. Some individuals with severe COVID-19 pneumonia may develop a "cytokine storm," an overactive immune response that may result in tissue damage and organ malfunction. The underlying mechanisms of immune suppression in SARS-CoV-2 are not entirely comprehended at this time, and ongoing research is being conducted to gain a more comprehensive understanding. Research has shown that severe SARS-CoV-2 infection promotes the synthesis of IgG4 antibodies. In this work, we propose the hypothesis that the IgG4 antibody produced by B cells in response to infection by SARS-CoV2 generates immunological tolerance that prevents its elimination, and leads to persistence and chronic infection. In sum, we believe that this constitutes another immune evasion mechanism that bears striking similarities to that developed by cancer cells to evade immune surveillance.
HYPOTHESIS | doi:10.20944/preprints202211.0407.v1
Subject: Medicine And Pharmacology, Psychiatry And Mental Health Keywords: Autism; autism spectrum disorder; autophagy; macrophage polarization; neurogenesis; taurine
Online: 22 November 2022 (05:46:47 CET)
Contemporary research has found that people with autism spectrum disorder (ASD) exhibit aberrant immunological function, with a shift toward increased cytokine production and unusual cell function. Microglia and astroglia were found to be significantly activated in immuno-cytochemical studies, and cytokine analysis revealed that the macrophage chemoattractant protein-1 (MCP-1), interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and transforming growth factor β-1 (TGFB-1), all generated in the neuroglia, constituted the most predominant cytokines in the brain. Taurine (2-aminoethanesulfonic acid) is a promising therapeutic molecule able to increase the activity of antioxidant enzymes and ATPase, which may be protective against aluminum-induced neurotoxicity. It can also stimulate neurogenesis, synaptogenesis, and reprogramming of proinflammatory M1 macrophage polarization by decreasing mitophagy (mitochondrial autophagy) and raising the expression of the markers of the anti-inflammatory and pro-healing M2 macrophages, such as macrophage mannose receptor (MMR, CD206) and IL-10, while lowering the expression of the M1 inflammatory factor genes. Taurine also induces autophagy, which is a mechanism that is impaired in microglia cells and is critically associated with the pathophysiology of the ASD. We hypothesize here that taurine could reprogram the metabolism of M1 macrophages that are overstimulated in the nervous system of people suffering from ASD, thereby decreasing the neuroinflammatory process, neuronal death, and improving cognitive functions. Therefore, we think that taurine can serve as an important lead for the development of novel drugs for the ASD treatment.
REVIEW | doi:10.20944/preprints202207.0051.v1
Subject: Medicine And Pharmacology, Pulmonary And Respiratory Medicine Keywords: SARS-CoV-2; Omicron; variant of concern
Online: 4 July 2022 (10:28:04 CEST)
For the first time in history, we have witnessed the origin and development of a pandemic. To handle the accelerated accumulation of viral mutations and to comprehend the virus' evolutionary adaptation in humans, an unparalleled program of genetic sequencing and monitoring of SARS-CoV-2 variants has been undertaken. Several scientists have theorized that, with the Omicron surge producing a more contagious but less severe disease, the end of COVID-19 is near. However, by analyzing the behavior shown by this virus for 2 years, we have noted that pandemic viruses do not always show a decreased virulence. Instead, it appears there is an evolutionary equilibrium between transmissibility and virulence. We have termed this concept “intermittent virulence”. The present work analyzes the temporal and epidemiological behavior of SARS-CoV-2 and suggests that there is a high possibility that new virulent variants will arise in the near future, although it is improbable that SARS-CoV-2´s virulence will be the same as was seen during the pandemic phase.
ARTICLE | doi:10.20944/preprints202105.0492.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Drug resistance; nsp12; protein design; fitness; RNA-dependent RNA polymerase; resistance mutations; SARS-CoV-2.
Online: 20 May 2021 (13:18:14 CEST)
Favipiravir is a broad-spectrum inhibitor of viral RNA-dependent RNA polymerase (RdRp) currently being used to manage COVID-19 in several countries. By acting as a substrate for RdRp, favipiravir gets incorporated into the nascent viral RNA and prevents strand extension. A high mutation rate of SARS-CoV-2 RdRp may facilitate antigenic drift as an answer to the host immune response, thereby generating resistance of virus to favipiravir. Therefore, it is extremely crucial to predict potential mutational sites in the RdRp and the emergence of structural modifications contributing to drug resistance. Here, we used high-throughput interface-based protein design to generate >100,000 designs and identify mutation hotspot residues in the favipiravir-binding site of RdRp. Several mutants had lower binding affinities to favipiravir, out of which hotspot residues with a high propensity to undergo positive selection were identified. The results showed that the designs retained an average of 97 to 98% sequence identity, suggesting that SARS-CoV-2 can develop favipiravir resistance with just a few mutations. Notably, we observed that out of 134 mutations predicted designs, 63 specific mutations were already present in the CoV-GLUE database, thus attaining ~47% correlation match with the clinical sequencing data. The findings improve our understanding of the potential signatures of adaptation in SARS-CoV-2 against favipiravir and management of COVID-19. Furthermore, they can help develop exhaustive strategies for robust antiviral design and discovery.
REVIEW | doi:10.20944/preprints202307.1094.v1
Subject: Medicine And Pharmacology, Epidemiology And Infectious Diseases Keywords: non-specific effects of vaccines; tolerance; immune training; excess deaths; IgG4 antibodies.
Online: 17 July 2023 (09:59:57 CEST)
Contrary to the long-held belief that the effects of vaccines are specific for the disease they were created; compelling evidence has demonstrated that vaccines can exert positive or deleterious non-specific effects (NSEs). In this review, we compiled research reports from the last 40 years, showing that live vaccines induce positive NSEs, whereas non-live vaccines induce several negative NSEs, including increased female mortality associated with enhanced susceptibility to other infectious diseases, especially in developing countries. These negative NSEs are determined by the vaccination sequence, the antigen concentration in vaccines, the type of vaccine used (live vs. non-live), and also by repeated vaccination. We do not recommend stopping using non-live vaccines, as they have demonstrated to protect against their target disease, so the suggestion is that their detrimental NSEs can be minimized simply by changing the current vaccination sequence. High IgG4 antibody levels generated in response to repeated inoculation with mRNA COVID-19 vaccines could be associated with a higher mortality rate from unrelated diseases and infections by suppressing the immune system. Since most COVID-19 vaccinated countries are reporting high percentages of excess mortality not directly attributable to deaths from such disease, the NSEs of mRNA vaccines on overall mortality should be studied in depth.
HYPOTHESIS | doi:10.20944/preprints202303.0441.v1
Subject: Medicine And Pharmacology, Pulmonary And Respiratory Medicine Keywords: IgG4 antibodies; mRNA vaccines; immuno-tolerance; auto-immunity; SARS-CoV-2; COVID-19.
Online: 27 March 2023 (03:56:26 CEST)
Due to the health crisis caused by SARS-CoV-2, the creation of a new vaccine platform based on mRNA was implemented. Globally, around 13.32 billion COVID-19 vaccine doses of diverse platforms have been given, and up to this date, 69.7% of the total population received at least one injection of a COVID-19 vaccine. Although these vaccines prevent hospitalization and severe forms of the disease, increasing evidence has shown they do not produce sterilizing immunity, allowing people to suffer frequent re-infections. Recent research has also raised concerns that mRNA vaccines could induce immune tolerance, which, added to that caused by the virus itself, could complicate the clinical course of a COVID-19 infection. Furthermore, recent investigations have found high IgG4 levels in people who were administered two or more injections of mRNA vaccines. It has been suggested that an increase in IgG4 levels could have a protecting role by preventing immune over-activation, similar to that occurring during successful allergen-specific immunotherapy by inhibiting IgE-induced effects. Altogether, evidence suggests that the reported increase in the IgG4 levels detected after repeated vaccination with the mRNA vaccines is not a protective mechanism; rather, it may be a part of the immune tolerance mechanism to the spike protein that could promote unopposed SARS-CoV2 infection and replication by suppressing natural antiviral responses. IgG4-induced suppression of the immune system due to repeated vaccination can also cause autoimmune diseases, promotes cancer growth, and autoimmune myocarditis in susceptible individuals.
Subject: Medicine And Pharmacology, Pulmonary And Respiratory Medicine Keywords: pangolin; intrinsic; disorder; protein; nucleocapsid; Nipah; virulence; viral protein; protein structure; protein function; shell; covid; coronavirus; ebola; vaccine; immune; antibody; shell; nucleoprotein; matrix; attenuate
Online: 28 June 2020 (09:16:27 CEST)
A model to predict the relative levels of respiratory and fecal-oral transmission potentials of coronaviruses (CoVs) by measuring the percentage of protein intrinsic disorder (PID) of the M (Membrane) and N (nucleoprotein) proteins in their outer and inner shells, respectively, was built before the MERS-CoV outbreak. Application of this model to the 2003 SARS-CoV indicated that this virus with MPID = 8.6% and NPID = 50.2% falls into group B, which consists of CoVs with intermediate levels of both fecal-oral and respiratory transmission potentials. Further validation of the model came with MERS-CoV (MPID = 9%, NPID = 44%) and SARS-CoV-2 (MPID = 5.5%, NPID = 48%) falling into the groups C and B, respectively. Group C contains CoVs with higher fecal-oral but lower respiratory transmission potentials. Unlike SARS-CoV, SARS-CoV-2 with MPID = 5.5% has one of the hardest outer shells among CoVs. This shell hardness is believed to be responsible for high viral loads in the mucus and saliva making it more contagious than SARS-CoV. The hard shell is able to resist the anti-microbial enzymes in body fluids. Further searches have found that high rigidity of outer shell is characteristic for the CoVs of burrowing animals, such as rabbits (MPID = 5.6%) and pangolins (MPID = 5-6%), which are in contact with the buried feces. A closer inspection of pangolin-CoVs from 2017-19 reveals that these animals provided a unique window of opportunity for the entry of an attenuated SARS-CoV-2 precursor into the human population in 2017 or earlier, with the subsequent slow and silent spread as a mild cold that followed by its mutations into the current more virulent form. Evidence of this lies in the similarity of shell disorder and genetic proximity of the pangolin-CoVs to SARS-CoV-2 (~90%). A 2017 pangolin-CoV strain shows evidence of higher levels of attenuation and higher fecal-oral transmission associated with lower human infectivity via having lower NPID (44.8%). Our shell disorder analysis also revealed that lower inner shell disorder is associated with the lesser virulence in a variety of viruses.
ARTICLE | doi:10.20944/preprints202308.1014.v1
Subject: Computer Science And Mathematics, Artificial Intelligence And Machine Learning Keywords: Artificial Intelligence; Generative Pre-Trained Transformers (GPT); Intrinsically Disordered Proteins (IDPs); Large Language Models (LLMs); Pathways Language Model 2 (PaLM 2)
Online: 14 August 2023 (09:44:19 CEST)
(1) Background: Artificial Intelligence (AI) models have shown potential in various educational contexts. However, their utility in explaining complex biological phenomena, such as Intrinsically Disordered Proteins (IDPs), requires further exploration. This study empirically evaluated the performance of various Large Language Models (LLMs) in the educational domain of IDPs. (2) Methods: Four LLMs, GPT-3.5, GPT-4, GPT-4 with Browsing, and Google Bard (PaLM 2), were assessed using a set of IDP-related questions. An expert evaluated their responses across five categories: accuracy, relevance, depth of understanding, clarity, and overall quality. Descriptive statistics, ANOVA, and Tukey's honesty significant difference tests were utilized for analysis. (3) Results: The GPT-4 model consistently outperformed the others across all evaluation categories. Although GPT-4 and GPT-3.5 were not statistically significantly different in performance (p>0.05), GPT-4 was preferred as the best response in 13 out of 15 instances. The AI models with browsing capabilities, GPT-4 with Browsing and Google Bard (PaLM 2) displayed lower performance metrics across the board with statistically significant differences (p<0.0001). (4) Conclusion: Our findings underscore the potential of AI models, particularly LLMs such as GPT-4, in enhancing scientific education, especially in complex domains such as IDPs. Continued innovation and collaboration among AI developers, educators, and researchers are essential to fully harness the potential of AI for enriching scientific education.
REVIEW | doi:10.20944/preprints202008.0696.v1
Subject: Biology And Life Sciences, Virology Keywords: COVID-19; SARS-CoV-2; neurotropic virus; Blood-nervous system barrier; bloodcerebrospinal-fluid-barrier; blood-brain-barrier; blood-nerve barrier; olfactory route; Lymphatic brain drainage route; Peripheral nerve or neuronal retrograde route; Macrophage/monocytes cargo route; Double membrane vesicles cargo route; nicotinic acetylcholine receptor
Online: 31 August 2020 (04:43:34 CEST)
Without protective and/or therapeutic agents the SARS-CoV-2 infection known as coronavirus disease 2019 (COVID-19) is quickly spreading worldwide. It has surprising transmissibility potential, since it could infect all ages, gender, and human sectors. It attacks respiratory, gastrointestinal, urinary, hepatic, and endovascular systems and can reach the peripheral nervous system (PNS) and central nervous system (CNS) through known and unknown mechanisms. The reports on the neurological manifestations and complications of the SARS-CoV-2 infection are increasing exponentially. Herein, we enumerate seven candidate routes, which the mature or immature SARS-CoV-2 components could use to reach the CNS and PNS, utilizing the within-body crosstalk between organs. The majority of SARS-CoV-2 infected patients suffer from some neurological manifestations (e.g., confusion, anosmia, and ageusia). It seems that although the mature virus did not reach the CNS or PNS of the majority of patients, its unassembled components and/or the accompanying immune-mediated responses may be responsible for the observed neurological symptoms. The viral particles and/or its components have been specifically documented in endothelial cells of lung, kidney, skin, and CNS. This means that the blood-endothelial-barrier may be considered as the main route for SARS-CoV-2 entry into the nervous system, with the barrier disruption being more logical than barrier permeability, as evidenced by postmortem analyses.
ARTICLE | doi:10.20944/preprints202307.2015.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: L,D-peptidase; bacteriophage; catalysis; substrate binding; calcium
Online: 28 July 2023 (12:29:31 CEST)
Bioinformatics analysis of the sequences of orthologous zinc-containing peptidases of the M15_C subfamily revealed the presence of a conserved tryptophan residue near the active site, which is not involved in the formation of the protein core. Site-directed mutagenesis of this Trp114/109 residue using two representatives of the family, L-alanoyl-D-glutamate peptidases of bacteriophages T5 (Calcium-activated EndoT5) and RB49 (EndoRB49, without ion regulation) as an example, and further analysis of the 1H NMR spectra of the mutants showed that a decrease in the volume of the W → F → A residue leads to changes in the hydrophobic core and active center of the protein, and also decreased affinity for regulatory Ca2+ in the EndoT5 mutants. The inactive T5W114A mutant lacks the ability to bind the substrate. In general, the conserved Trp114/109 residue, due to the spatial restrictions of its side chain, significantly affects the formation of the catalytically active form of the enzyme and is critical for catalysis.
REVIEW | doi:10.20944/preprints202303.0448.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: LLPS; liquid-liquid phase separation; non-coding RNA; intrinsically disordered proteins; membrane-less organelles; stress-response; biomolecular condensates
Online: 27 March 2023 (05:43:50 CEST)
At the beginning of the 21st century, it became obvious that radical changes had taken place in the concept of living matter and, in particular, in the concept of the organization of intracellular space. The accumulated data testify to the essential importance of phase transitions of biopolymers (first of all, intrinsically disordered proteins and RNA) in the spatiotemporal organization of the intracellular space. Of particular interest is the stress-induced reorganization of the intracellular space. Examples of organelles formed in response to stress are nuclear A-bodies and nuclear stress granules. The formation of these organelles is based on LLPS of intrinsically disordered proteins and non-coding RNA. Despite the overlapping composition and similar mechanism of formation, these organelles have different functional activities and physical properties. In this review, we will focus our attention on these MLOs and describe their functions, structure, and mechanism of formation.
ARTICLE | doi:10.20944/preprints202304.1265.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: amyloid bodies; intrinsically disordered protein; liquid-liquid phase separation; membrane-less organelle; nuclear stress bodies; nucleolar biomolecular condensates
Online: 30 April 2023 (05:18:24 CEST)
Radical changes in the idea of the organization of the intracellular space that occurred in the early 2010-s made it possible to consider the formation and functioning of the so-called membrane-less organelles (MLOs) based on a single physical principle: the liquid-liquid phase separation (LLPS) of biopolymers. Weak nonspecific inter- and intramolecular interactions of disordered polymers, primarily of intrinsically disordered proteins and RNA, play a central role in the initiation and regulation of these processes. On the other hand, in some cases, the "maturation" of MLOs can be accompanied by the "liquid-gel” phase transition, where other types of interactions can play a significant role in reorganization of their structure. In this work, we conducted a bioinformatics analysis of the propensity of the proteomes of two membrane-less organelles formed in response to stress in the same compartment, nucleolus, for spontaneous phase separation and looked at their intrinsic disorder predispositions. These nucleolar MLOs, amyloid bodies (A-bodies) formed in the response to acidosis and heat shock and nuclear stress bodies (nSBs), are characterized by the partially overlapping composition, but show different functional activities and morphologies. We show that the proteomes of these nucleolar biocondensates are differently enriched in proteins, many of with high potential for spontaneous LLPS that correlates with different morphology and function of these organelles. The results of these analyses allowed us to evaluate the role of weak interactions in the formation and functioning of these important organelles.
ARTICLE | doi:10.20944/preprints202210.0404.v1
Subject: Biology And Life Sciences, Virology Keywords: COVID-19; SARS-CoV-2 Omicron; tMRCA; evolutionary rate; mutational profiling; selection pressure
Online: 26 October 2022 (08:15:25 CEST)
The ongoing evolution of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has resulted in the recent emergence of a highly divergent variant of concern (VOC) defined as Omicron or B.1.1.529. This VOC is of particular concern because it has the potential to evade most therapeutic antibodies and has undergone a sustained genetic evolution, resulting in the emergence of five distinct sub-lineages. However, the evolutionary dynamics of initially identified Omicron BA.1 and BA.2 sub-lineages remain poorly understood. Herein, we combined Bayesian phylogenetic analysis, mutational profiling, and selection pressure analysis to track virus genetic changes that drive the early evolutionary dynamics of the Omicron. Based on the Omicron dataset chosen for the improved temporal signals and sampled globally between November 2021 and January 2022, most recent common ancestor (tMRCA) and substitution rates for BA.1 were estimated to be 18 September 2021 (95% highest posterior density (HPD) 04 August – 22 October 2021) and 1.435×10-3 (95% HPD = 1.021×10-3 – 1.869×10-3) substitution/site/year, respectively, whereas 03 November 2021 (95% highest posterior density (HPD) 26 September – 28 November 2021) and 1.074×10-3 (95% HPD = 6.444×10-4 – 1.586×10-3) substitution/site/year for BA.2 sub-lineage. The findings of this study suggest that the Omicron BA.1 and BA.2 sub-lineages originated independently and evolved over time. Furthermore, we identified multiple sites in spike protein undergoing continued diversifying selection that may alter the neutralization profile of BA.1. This study shed light on the ongoing global genomic surveillance and Bayesian molecular dating analyses to better understand the evolutionary dynamics the virus and, as a result, mitigate the impact of emerging variants on public health.
ARTICLE | doi:10.20944/preprints202310.1400.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: PMLbodies; intrinsically disordered proteins; intrinsically disordered regions; liquidliquid phase separation; membrane-less organelles; protein-protein interactions; posttranslational modifications; SUMOyltion
Online: 23 October 2023 (10:49:13 CEST)
The formation and functioning of membrane-less organelles (MLOs) is one of the main driving forces in the molecular life of the cell. These processes are based on the separation of biopolymers into phases regulated by multiple specific and nonspecific inter- and intramolecular interactions. Among the realm of MLOs, a special place is taken by the promyelocytic leukemia nuclear bodies (PML-NBs or PML bodies), which are the intranuclear compartments involved in the regulation of cellular metabolism, transcription, maintenance of genome stability, response to viral infection, apoptosis, and tumor suppression. According to the accepted models, specific interactions, such as SUMO/SIM, formation of disulfide bonds, etc., play a decisive role in the biogenesis of PML bodies. In this work, a number of bioinformatics approaches were used to study proteins found in the proteome of PML-bodies for their tendency to spontaneous liquid-liquid phase separation (LLPS), which is usually caused by weak nonspecific interactions. 205 proteins found in PML bodies have been identified. It has been suggested that UBC9, P53, HIPK2, and SUMO1 can be considered as the scaffold proteins of PML bodies. It was shown that more than half of the proteins in the analyzed proteome are capable of spontaneous LLPS, with 85% of the analyzed proteins being intrinsically disordered proteins (IDPs), and remaining 15% being proteins with intrinsically disordered protein regions (IDPRs). About 44% of all proteins analyzed in this study contain SUMO binding sites and can potentially be SOMYylated. These data suggest that weak nonspecific interactions play a significantly larger role in the formation and biogenesis of PML bodies than previously expected.
ARTICLE | doi:10.20944/preprints202308.1057.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: Targeted delivery; A6 peptide; PCL-PEG; Nanoparticle; Nanopolymer; Curcumin; Cancer
Online: 14 August 2023 (15:36:50 CEST)
Polymeric based nanoparticles are garnering significant interest for their potential in drug delivery. Specially, nanopolymers that have been functionalized with molecules, such as proteins or peptides, are a versatile vehicle for drug delivery. Curcumin (Cur) is one of the most commonly studied anticancer compounds and is widely acknowledged as having positive effects on human health. However, its insolubility and low bio-distribution greatly hinder the exploitation of its beneficial traits. In this study, our team created a nano delivery system which utilized a nanopolymer called PCL-PEG (poly(ε-caprolactone)-poly (ethylene glycol)). This system was functionalized with A6 peptide to enable targeted delivery of Cur. The system was designed with advantageous nanoparticles (NPs), including a stable zeta potential (–32.7), small size (54.3), uniform surface morphology, and high hydrophilicity (13.72°). In addition, targeted delivery systems exhibited high encapsulation efficacy (93 ± 0.89 %), and drug loading (16.7 ± 0.9 %), and were characterized by a slow and gradual release profile with a release of approximately 83.13 ± 0.12%. The MTT assay results showed that the formulation known as Cur-NPs-A6 caused a significant increase in cell death in MDA-MB-231 cancer cells (IC50 = 23.31 ± 0.85 µM). The designed delivery system did not cause any harm to the noncancerous MCF-10A cells (normal group). Furthermore, the results of both the RT-qPCR and invasion assays demonstrated that the designed system was able to effectively activate the apoptosis pathway and inhibit cell invasion. Our findings suggest that the use of the designed smart delivery system, which is functionalized with A6 peptide that has a high affinity for CD44 receptor - known to be upregulated in numerous malignant conditions, could be a highly efficient approach to treating cancer.
ARTICLE | doi:10.20944/preprints202209.0319.v1
Subject: Biology And Life Sciences, Biophysics Keywords: cytokine; S100 protein; S100P; protein–protein interaction
Online: 21 September 2022 (09:45:39 CEST)
S100 proteins are multifunctional calcium-binding proteins of vertebrates that act intracellularly, extracellularly, or both, and are engaged in the progression of many socially significant diseases. Their extracellular action is typically mediated by the recognition of specific receptor proteins. Besides, recent studies indicate the ability of some S100 proteins to affect cytokine signaling through direct interaction with cytokines. S100P was shown to be the S100 protein most actively involved in interactions with some of four-helical cytokines. To assess selectivity of S100P protein binding to four-helical cytokines, we have probed interaction of Ca2+-bound recombinant human S100P with a panel of 32 four-helical human cytokines covering all structural families of this fold, using surface plasmon resonance spectroscopy. 22 cytokines from all families of four-helical cytokines are S100P binders with the equilibrium dissociation constants, Kd, ranging from 1 nM to 3 µM (below the Kd value for the S100P complex with the V domain of its conventional receptor, receptor for advanced glycation end products, RAGE). Molecular docking and mutagenesis studies revealed the presence in the S100P molecule of a cytokine-binding site, which overlaps with the RAGE-binding site. Since S100 binding to four-helical cytokines inhibits their signaling in some cases, the revealed ability of S100P protein to interact with ca 71% of the four-helical cytokines indicates that S100P may serve as a poorly selective inhibitor of their action.
ARTICLE | doi:10.20944/preprints202308.1202.v2
Subject: Biology And Life Sciences, Life Sciences Keywords: exosomes; extracellular vesicles; isolation methods; ultrafiltration; precipitation; ultracentrifugation
Online: 18 August 2023 (08:19:24 CEST)
Extracellular vesicles (EVs) are enclosed by a lipid-bilayer membrane and secreted by all types of the cells under various physiological conditions. EVs play important roles in intercellular communication and crosstalk between tissues in the body. They are classified into three groups, such as apoptotic bodies, microvesicles, and exosomes. Exosomes were isolated from biofluids including blood, urine, milk, and cell culture media. Exosomes have significant potential for drug delivery and diagnosis. However, the method of isolation affects the physical and biological properties of exosomes. Several methods based on different principles have been developed for exosome isolation. These include ultrafiltration, precipitation, ultracentrifugation, size-exclusion chromatography, and microfluidics. In this study, we applied three common methods, such as ultrafiltration, precipitation, and ultracentrifugation, to isolate exosomes from the cell culture medium and investigated the effects of these different isolation methods on the size distribution and quality of the isolated exosomes. Field emission scanning electron microscopy (FESEM) images, size distribution, total protein content, and the effect of exosomes on the viability of hypoxic cells were analyzed in this study. The analysis revealed that compared to other methods, the ultracentrifugation method can isolate exosomes with smaller diameter (ranging from 20 to 80 nm), lower total protein content (50 µg/ml), and causing the increased viability of the hypoxic cells. The precipitation method does not require special equipment and is inexpensive, if the quality and purity of this method are solved, and it can be used as the best method for exosome isolation. This study can serve as a guide for choosing the best exosome isolation method for applications in medicine according to the needs, time, cost, and equipment.
ARTICLE | doi:10.20944/preprints202307.2030.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: cytokine; EF-hand; S100 protein; S100A6; protein–protein interaction
Online: 28 July 2023 (12:40:50 CEST)
S100 is a family of over 20 structurally homologous, but functionally diverse regulatory (calcium/zinc)-binding proteins of vertebrates. The involvement of S100 proteins in numerous vital (patho)physiological processes is mediated by their interaction with various (intra/extra)cellular protein partners, including cell surface receptors. Furthermore, recent studies revealed the ability of specific S100 proteins to affect cell signaling via direct interaction with cytokines. Previously, we have revealed binding of ca. 71% of the four-helical cytokines by S100P protein due to the presence in its molecule of a cytokine-binding site, which overlaps with the binding site for S100P receptor. Here we show that another S100 protein, S100A6 (pairwise sequence identity with S100P of 35%), specifically binds numerous four-helical cytokines. We have studied affinity of recombinant forms of 35 human four-helical cytokines covering all structural families of this fold to Ca2+-loaded recombinant human S100A6, using surface plasmon resonance spectroscopy. S100A6 recognizes 26 of the cytokines from all families of this fold with the equilibrium dissociation constants ranging from 0.3 nM to 12 µM. Overall, S100A6 interacts with ca. 73% of the four-helical cytokines studied to date with selectivity equivalent to that for S100P protein, with the differences limited to binding of Interleukin-2 and Oncostatin-M. The molecular docking study evidences presence in S100A6 molecule of a cytokine-binding site, analogous to that found in S100P. The findings argue the presence in some of the promiscuous members of S100 family of a site specific to a wide range of the four-helical cytokines. This unique feature of the S100 proteins potentially allows them to serve as universal inhibitors of signaling of the four-helical cytokines, which could be of value for reduction of severity of the disorders accompanied by excessive release of the cytokines.
ARTICLE | doi:10.20944/preprints202311.0853.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: liquid-liquid phase separation; membrane-less organelles; stress granules; P-bodies; intrinsically disordered proteins; intrinsically disordered regions; aging; senescence; protein aggregation; nucleic acids; RNA-binding protein; DNA-binding protein
Online: 14 November 2023 (16:38:59 CET)
At the molecular level, aging is often accompanied by dysfunction of stress-induced membrane-less organelles (MLOs) and changes in their material state. In this work, we analyzed the proteins included in the proteome of stress granules (SGs) and P-bodies for their tendency to transform the material state of these MLOs. Particular attention was paid to proteins whose gene expression changes during replicative aging. It was shown that the proteome of the studied MLOs practically does not differ in the analyzed characteristics and consists of completely or partially intrinsically disordered proteins, 30 - 40% of which are potentially capable of liquid-liquid phase separation (LLPS). At the same time, the proportion of proteins capable of spontaneous LLPS is relatively small, which indicates the leading role of nucleic acids in the biogenesis of these membrane-less organelles. Proteins whose gene expression changes during the transition of human cells to a senescent state make up about 20% of the studied proteomes. There is a statistically significant increase in the number of positively charged proteins in both datasets studied compared to the complete proteomes of these organelles. An increase in the relative content of DNA-, but not RNA-binding proteins, was also found in the stress-granules dataset with senescence-related processes. Among SG proteins potentially involved in senescent processes, there is an increase in the abundance of potentially amyloidogenic proteins compared to the whole proteome. The hnRPDL protein has the highest degree of disorder and highest propensity for LLPS among such proteins, which allows us to consider it as “potentially dangerous.” Proteins common to SGs and P bodies, potentially involved in processes associated with senescence, form clusters of interacting proteins. The largest cluster is represented by RNA-binding proteins involved in RNA processing and translation regulation. These data indicate that SG proteins, but not proteins of P-bodies, are more likely to transform the material state of MLOs. Furthermore, these MLOs can participate in processes associated with aging in a coordinated manner.
ARTICLE | doi:10.20944/preprints202208.0327.v1
Subject: Biology And Life Sciences, Biophysics Keywords: Fourier Transform Infrared spectroscopy; water structure; hydrogen bonds; protein solution; solvent properties
Online: 18 August 2022 (03:25:26 CEST)
This work presents the first evidence that dissolved globular proteins change the arrangement of hydrogen bonds in water, with different proteins showing quantitatively different effects. Using ATR-FTIR (Attenuated Total Reflection – Fourier Transform Infrared) spectroscopic analysis of OH-stretch bands, we obtain quantitative estimates of the relative amounts of the previously reported four subpopulations of water structures coexisting in a variety of aqueous solutions. Where solvatochromic dyes can measure the properties of solutions of non-ionic polymers, the results correlate well with ATR-FTIR measurements. In protein solutions to which solvatochromic dye probes cannot be applied, NMR (Nuclear Magnetic Resonance) spectroscopy was used for the first time to estimate the hydrogen bond donor acidity of water. We found strong correlations between the solvent acidity and arrangement of hydrogen bonds in aqueous solutions for several globular proteins. Even quite similar proteins are found to change water properties in dramatically different ways.
ARTICLE | doi:10.20944/preprints202107.0585.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Functional receptor; Hepatitis B virus; Polymorphism; Sodium taurocholate co-transporting polypeptide; hepatic fibrosis; Egypt
Online: 26 July 2021 (14:42:42 CEST)
Background: Single nucleotide polymorphisms (SNPs) in the SLC10A1 gene, coding for a functional receptor of hepatitis B virus (HBV), sodium taurocholate co-transporting polypeptide (NTCP), may influence the susceptibility, the outcome, and disease course of HBV infection in some populations. Aim: to determine the prevalence of SNPs of NTCP gene, rs2296651 and rs943277, and their relationship with chronic HBV infection in a group of Egyptian patients. Methods: 137 patients with HBV and 65 healthy controls were enrolled, and the patients were divided into two groups; group I chronic HBV infection (68 patients with normal ALT and minimal or no liver necroinflammation or fibrosis) and group II chronic hepatitis B (69 patients with elevated ALT and moderate or severe liver necroinflammation). They were subjected to full history taking, clinical examination, laboratory investigations, abdominal ultrasound, and liver stiffness measurement using both Echosens® Fibroscan and acoustic radiation force impulse (ARFI). Real time PCR TaqMan 5’ allelic discrimination assay was applied to detect the SNPs in NTCP gene, rs2296651 and rs943277. Results: On studying the rs2296651 variant, all controls and patients had genotype GG without any significant association with HBV infection or disease progression. However, the rs943277 variant in all controls and 98% of patients had genotype GA, except for two chronic HBV infection patients who had genotype AA, but no significant difference between patients and controls was found. The non-invasive methods for liver fibrosis assessment ARFI, AST/platelet's ratio (APRI), and fibrosis-4 score (FIB-4) could predict the stages of fibrosis in agreement with Fibroscan with AUCOR 0.8, 0.79, and 0.76, respectively. Conclusion: These findings may suggest that there is no relation between these SNPs of the NTCP gene and susceptibility or chronicity of HBV infection in the Egyptian population. We also suggest that the use of the non-invasive methods for liver fibrosis assessment, ARFI, FIB-4, and APRI may decrease the need for liver biopsies in prediction of significant hepatic fibrosis in chronic HBV patients.
ARTICLE | doi:10.20944/preprints202211.0313.v1
Subject: Biology And Life Sciences, Biophysics Keywords: cytokine; Tumor necrosis factor; S100 protein; protein–protein interaction; inflammatory diseases
Online: 16 November 2022 (13:12:59 CET)
Tumor necrosis factor (TNF) inhibitors (anti-TNFs) represent a cornerstone of the treatment of various immune-mediated inflammatory diseases and are among the most commercially successful therapeutic agents. Knowledge of TNF binding partners is critical for identification of the factors able to affect clinical efficacy of the anti-TNFs. Here we report that among eighteen representatives of the multifunctional S100 protein family only S100A11, S100A12 and S100A13 interact with the soluble form of TNF (sTNF) in vitro. The lowest equilibrium dissociation constants (Kd) for the complexes with monomeric sTNF determined using surface plasmon resonance spectroscopy range from 2 nM to 28 nM. The apparent Kd values for the complexes of multimeric sTNF with S100A11/A12 estimated from fluorimetric titrations are 0.1-0.3 µM. S100A12/A13 suppress the cytotoxic activity of sTNF against Huh-7 cells, as evidenced by the MTT assay. Structural modeling indicates that the sTNF-S100 interactions may interfere with the sTNF recognition by the therapeutic anti-TNFs. Bioinformatic analysis reveals dysregulation of TNF and S100A11/A12/A13 in numerous disorders. Overall, we have shown a novel potential regulatory role of the extracellular forms of specific S100 proteins that may affect efficacy of anti-TNF treatment in various diseases.
ARTICLE | doi:10.20944/preprints202311.0035.v2
Subject: Biology And Life Sciences, Life Sciences Keywords: GM-CSF; S100A4; S100A6; S100P; protein–protein interaction; cell viability
Online: 13 November 2023 (08:40:41 CET)
Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pleiotropic myelopoietic growth factor and proinflammatory cytokine, clinically used for multiple indications and serving as a promising target for treatment of many disorders, including cancer, multiple sclerosis, rheumatoid arthritis, psoriasis, asthma, COVID-19. We have previously shown that dimeric Ca2+-bound forms of S100A6 and S100P proteins, members of the multifunctional S100 protein family, are specific to GM-CSF. To probe selectivity of these interactions, the affinity of recombinant human GM-CSF to dimeric Ca2+-loaded forms of 18 recombinant human S100 proteins was studied by surface plasmon resonance spectroscopy. Of them, only S100A4 protein specifically binds to GM-CSF with equilibrium dissociation constant, Kd, values of 0.3-2 μM, as confirmed by intrinsic fluorescence and chemical crosslinking data. Calcium removal prevents S100A4 binding to GM-CSF, whereas monomerization of S100A4/A6/P proteins disrupts S100A4/A6 interaction with GM-CSF and induces a slight decrease in S100P affinity for GM-CSF. Structural modelling indicates the presence in the GM-CSF molecule of a conserved S100A4/A6/P-binding site, consisting of the residues from its termini, helices I and III, some of which are involved in the interaction with GM-CSF receptors. The predicted involvement of the ‘hinge’ region and F89 residue of S100P in GM-CSF recognition was confirmed by mutagenesis. Examination of S100A4/A6/P ability to affect GM-CSF signaling showed that S100A4/A6 inhibit GM-CSF/S100-induced suppression of viability of monocytic THP-1 cells. The ability of the S100 proteins to modulate GM-CSF activity is relevant to progression of various neoplasms and other diseases, according to bioinformatics analysis. The direct regulation of GM-CSF signaling by extracellular forms of the S100 proteins should be taken into account in the clinical use of GM-CSF and development of the therapeutic interventions targeting GM-CSF or its receptors.
ARTICLE | doi:10.20944/preprints202306.1882.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: Breast Cancer; Curcumin; Copolymer; Drug delivery; Nanoinformatics
Online: 27 June 2023 (10:23:03 CEST)
Curcumin (CUR) is a phytochemical with potent anticancer activities as demonstrated by both preclinical and clinical studies. CUR bioformulations, including loading in biodegradable polymers, have been explored to increase CUR’s solubility and chemical stability, control its release, and improve its delivery to cancer cells. In this study, copolymers comprising poly (L-lactide)-poly (ethylene glycol)-poly (L-lactide) (PLA-PEG-PLA) and poly (ethylene glycol)-poly (L-lactide)-poly (ethylene glycol) (PEG-PLA-PEG) were designed and synthesized to assess and compare their curcumin delivery capacity and inhibitory potency on MCF-7 breast cancer cells. Molecular dynamics simulations indicated that PLA-PEG-PLA has a higher propensity to interact with the cell membrane and more negative free energy, suggesting it is the better carrier for cell membrane penetration. Our characterization indicated that the microsphere copolymers were synthesized successfully. Of the two formulations, PLA-PEG-PLA experimentally exhibited better results, with an initial burst release of 17.5%, followed by a slow, constant release of the encapsulated drug up to 80%. PLA-PEG-PLA-curcumin showed a significant increase in cell death in MCF-7 cancer cells (IC50 = 23.01 ± 0.85 µM) based on the MTT assay. These data were consistent with gene expression studies of Bax, Bcl2, and hTERT which showed that PLA-PEG-PLA-CUR induced apoptosis more efficiently in these cells. Our study integrates in vitro and in silico approaches to identify an optimal co-polymer for the delivery of CUR to cancer cells.
COMMUNICATION | doi:10.20944/preprints202203.0185.v1
Subject: Medicine And Pharmacology, Pulmonary And Respiratory Medicine Keywords: SARS-CoV-2; COVID-19; variant; sublineage; transmission; immunity; infection; vaccination; non-pharmaceutical interventions
Online: 14 March 2022 (11:19:04 CET)
The scientific, private and industrial sectors use a wide variety of technological platforms available to achieve protection against SARS-CoV-2, including vaccines. However, the virus evolves continually into new highly virulent variants, which might overcome the protection provided by vaccines and may re-expose the population to infections. Mass vaccinations should be continued in combination with more or less obligation mandatory non-pharmaceutical interventions. Therefore, the key questions to be answered are: (i) How to identify the primary and secondary infections of SARS-CoV-2? (ii) Why are neutralizing antibodies not long-lasting in both the cases of natural infections and post-vaccinations? (iii) Which are the factors responsible for this decay in neutralizing antibodies? (iv) What strategy could be adapted to develop long-term herd immunity? (v) Is the Spike the only vaccine candidate or a vaccine cocktail is better?
ARTICLE | doi:10.20944/preprints202111.0558.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Yersinia pestis; vaccine; guinea pigs; bubonic plague; inactivated vaccine; phage; bacterial ghost; protection; protein-E-mediated lysis, holin-endolysin system
Online: 30 November 2021 (11:08:18 CET)
To develop a modern plague vaccine, we used hypo-endotoxic Yersinia pestis bacterial ghosts (BGs) with combinations of genes encoding the bacteriophage ɸX174 lysis-mediating protein E and/or holin-endolysin systems from λ or L-413C phages. Expression of the protein E gene resulted in the BGs that retained the shape of the original bacterium. Co-expression of this gene with genes coding for holin-endolysin system of the phage L-413C caused formation of structures resembling collapsed sacs. Such structures, which have lost their rigidity, were also formed as a result of the expression of only the L-413C holin-endolysin genes. Similar holin-endolysin system from phage λ containing mutated holin gene S and intact genes R-Rz coding for the endolysins caused generation of mixtures of BGs that had (i) practically preserved and (ii) completely lost their original rigidity. The addition of protein E to the work of this system shifted the equilibrium in the mixture towards the collapsed sacs. The collapse of the structure of BGs can be explained by endolysis of peptidoglycan sacculi. Immunizations of laboratory animals with the variants of BGs followed by infection with a wild-type Y. pestis strain showed that bacterial envelopes protected only cavies. BGs with peptidoglycan maximally hydrolyzed had a greater protectivity compared to BGs with preserved peptidoglycan skeleton.
ARTICLE | doi:10.20944/preprints202305.0170.v1
Subject: Biology And Life Sciences, Biophysics Keywords: FOF1-ATP synthase; chloroplasts; dimers; small-angle scattering; membrane proteins
Online: 4 May 2023 (03:21:52 CEST)
F-type ATP synthases play a key role in oxidative and photophosphorylation processes producing adenosine triphosphate (ATP) for most biochemical reactions in living organisms. In contrast to the mitochondrial FOF1-ATP synthases those of chloroplasts are known to be mostly monomers with approx. 15% fraction of oligomers interacting presumably non-specifically in a thylakoid membrane. To shed light to the nature of this difference we studied interactions of the chloroplast ATP synthases using small-angle X-ray scattering (SAXS) method. Here, we report evidence of I-shaped dimerization of solubilized FOF1-ATP synthases from spinach chloroplasts at different salinity. The structural data were obtained by SAXS and showed dimerization in response to changes in ionic strength. The best model describing SAXS data was two ATP-synthases connected through F1/F1’ parts, presumably via their δ-subunits, forming dimers with the “I” shape. Such I-shaped dimers might possibly connect the neighboring lamellae in thylakoid stacks assuming that the FOF1 monomers comprising such dimers are embedded in different thylakoid membranes. If this type of dimerization exists in nature, it might be one of the pathways of inhibition of chloroplast FOF1-ATP synthase for preventing of ATP hydrolysis in dark, when salinity in plant chloroplasts is rising. Together with a redox switch inserted into a γ-subunit of chloroplast FOF1 and lateral oligomerization, an I-shaped dimerization might comprise a subtle regulatory process of ATP synthesis and stabilize the structure of thylakoid stacks in chloroplasts.
ARTICLE | doi:10.20944/preprints202107.0554.v1
Subject: Biology And Life Sciences, Virology Keywords: SARS-CoV-2; ORF10; Co-mutations; Intrinsic Protein Disorder; Ubiquitin Ligase Complex
Online: 26 July 2021 (09:07:38 CEST)
The devastating impact of the ongoing coronavirus disease 2019 (COVID-19) on public health, caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has made fighting of the COVID-19 pandemic is a top priority in medical research and pharmaceutical development. Surveillance of SARS-CoV-2 mutations is essential for the comprehension of SARS-CoV-2 variant diversity and their impact on virulence and pathogenicity. The SARS-CoV-2 open reading frame 10 (ORF10) protein interacts with multiple human proteins CUL2, ELOB, ELOC, MAP7D1, PPT1, RBX1, THTPA, TIMM8B, and ZYG11B expressed in the lung tissues. Mutations and co-mutations in the emerging SARS-CoV-2 ORF10 variants are expected to impact the severity of the virus and its associated consequences. In this article, We highlight 128 single mutations and 35 co-mutations in the unique SARS-CoV-2 ORF10 variants in this article. The possible predicted effects of these mutations and co-mutations on the secondary structure of ORF10 variants and host protein interactomes are presented. The findings highlight the possible effects of mutations and co-mutations on the emerging 140 ORF10 unique variants from secondary structure and intrinsic protein disorder perspectives.
REVIEW | doi:10.20944/preprints202101.0297.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: COVID-19; SARS-CoV-2; carbon-based nanomaterials; antiviral properties; pneumonia
Online: 15 January 2021 (13:30:21 CET)
Therapeutic options for the highly pathogenic human Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2) causing the current pandemic Coronavirus disease (COVID-19) are urgently needed. COVID-19 is associated with viral pneumonia and acute respiratory distress syndrome causing significant morbidity and mortality. The proposed treatments for COVID-19, such as hydroxychloroquine, remdesivir and lopinavir/ritonavir, have shown little or no effect in the clinic. Additionally, bacterial and fungal pathogens contribute to the SARS-CoV-2 mediated pneumonia disease complex. The antibiotic resistance in pneumonia treatment is increasing at an alarming rate. Therefore, carbon-based nanomaterials (CBNs), such as fullerene, carbon dots, graphene, and their derivatives constitute a promising alternative due to their wide-spectrum antimicrobial activity, biocompatibility, biodegradability and capacity to induce tissue regeneration. Furthermore, the antimicrobial mode of action is mainly physical (e.g. membrane distortion), which is characterized by a low risk of antimicrobial resistance. In this review, we evaluated the literature on the antiviral activity and broad-spectrum antimicrobial properties of CBNs. CBNs had antiviral activity against 12 enveloped positive-sense single-stranded RNA viruses similar to SARS-CoV-2. CBNs with low or no toxicity to the humans are promising therapeutics against COVID-19 pneumonia complex with other viruses, bacteria and fungi, including those that are multidrug-resistant.
REVIEW | doi:10.20944/preprints202307.1595.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: Glioblastoma, Notch signaling, lncRNAs, miRNAs
Online: 24 July 2023 (10:51:59 CEST)
Glioblastoma multiforme (GBM) is a highly invasive brain malignancy originating from astrocytes, accounting for approximately 30% of central nervous system malignancies. Despite advancements in therapeutic strategies including surgery, chemotherapy, and radiopharmaceutical drugs, the prognosis for GBM patients remains dismal. The aggressive nature of GBM necessitates the identification of molecular targets and the exploration of effective treatments to inhibit its proliferation. The Notch signaling pathway, which plays a critical role in cellular homeostasis, becomes deregulated in GBM, leading to increased expression of pathway target genes such as MYC, Hes1, and Hey1, thereby promoting cellular proliferation and differentiation. Recent research has highlighted the regulatory role of non-coding RNAs (ncRNAs) in modulating Notch signaling by targeting critical mRNA expression at the post-transcriptional or transcriptional levels. Specifically, various types of ncRNAs, including long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), have been shown to control multiple target genes and significantly contribute to the carcinogenesis of GBM. Furthermore, these ncRNAs hold promise as prognostic and predictive markers for GBM. This review aims to summarize the latest studies investigating the regulatory effects of ncRNAs on the Notch signaling pathway in GBM.
ARTICLE | doi:10.20944/preprints202106.0472.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: SARS-CoV-2; Mutations; Furin Cleavage Site (FCS); Evenly-uneven; Invariant regions
Online: 18 June 2021 (09:22:08 CEST)
Several hypotheses have been presented on the origin of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from its identification as the agent causing the current coronavirus disease 19 (COVID-19) pandemic. So far, no hypothesis has managed to identify the origin, and the issue has resurfaced. Here we have unfolded a pattern of distribution of several mutations in the SARS-CoV-2 proteins across different continents comprising 24 geo-locations. The results showed an evenly uneven distribution of unique protein variants, distinct mutations, unique frequency of common conserved residues, and mutational residues across the 24 geo-locations. Furthermore, ample mutations were identified in the evolutionarily conserved invariant regions in the SARS-CoV-2 proteins across almost all geo-locations we have considered. This pattern of mutations potentially breaches the law of evolutionary conserved functional units of the beta-coronavirus genus. These mutations may lead to several novel SARS-CoV-2 variants with a high degree of transmissibility and virulence. A thorough investigation on the origin and characteristics of SARS-CoV-2 needs to be conducted in the interest of science and to be prepared to meet the challenges of potential future pandemics.