Glycosylation, the most significant modification of proteins, plays an essential role in cellular processes. Congenital disorders of glycosylation (CDG) are multisystemic diseases resulting from mutations affecting glycosylation steps. Diagnosis of CDG relies on biochemical assays, such as isoelectric focusing. Despite its significance, CDG cases remain unreported in Cuba due to the lack of implemented diagnostic methods. This study aimed to evaluate transferrin glycoforms for diagnosing congenital N-glycosylation defects. We conducted a cross-sectional descriptive study using serum samples from 17 patients stored at the National Center for Medical Genetics of Cuba for suspected CDG. Results revealed abnormal glycosylation patterns in 7 patients, suggesting congenital N-glycosylation defects. We conclude that the implementation of transferrin glycoform analysis could pioneer a preliminary diagnosis of CDG in Cuba.

Glycosylation is a common post-translation modification present on majority of eukaryotic proteins. Therefore, it is dependent on the host cell line and affected by the cell culture and purification process. Additionally, glycosylation of therapeutic biologics is known to have a profound impact on binding and downstream effector functions. Hence, glycosylation is increasingly considered a critical quality attribute (CQA) of biopharmaceutical drugs and has been showed to affect the safety and efficacy of these molecules. Therefore, regulatory agencies have adopted a Quality by Design (QbD) approach for glycan monitoring at various steps with stringent controls to ensure efficacy and safety. This requires multiple, orthogonal fit-for-purpose tools to study the process. One key unmet need in downstream organizations of large pharmaceutical companies is a real-time, rapid glycan detection and quantification tool to guide purification/expression process. To meet this need, we have developed a selective, colorimetric assay which selectively stains sugar moieties (glycosylated IgGs) which appears as magenta bands on an SDS-PAGE resolved gel. The selectivity arises because the method leverages stereochemical differences of hydroxyl groups between amino acids and carbohydrates to selectively stain the primary alcohol in carbohydrates but not in amino acids. Specifically, our method selectively oxidizes the ‘cis-diol’ group in carbohydrates to aldehydes and stains the aldehydes on an SDS-PAGE gel by Schiff’s reaction. Our method is semi-quantitative and has comparable sensitivity to Coomassie with LoD of around 50ng. The method can detect glycosylated IgGs produced in multiple cell lines (including HEK and CHO), thereby enabling us to study batch-to-batch variability and can critically stain both N-linked and O-linked glycosylation. We also show that the assay can be used as a downstream purification guide for process analytics following ion-exchange and hydrophobic interaction chromatography.

Some of the most recent advances in enzymatic glycosylation processes focused on the production of important bioactive compounds have been analyzed. The applicability of different enzymes such as glycosidases, glycosyltransferases, glycophosphorylases and glycosynthases have been de-scribed around the review article considering their advantages and disadvantages of these biocat-alysts in the stereoselective and regioselective synthesis of different types of glycosylated mole-cules, phenolic and aliphatic alcohols, oligosaccharides, polysaccharides, glycoderivatives, glyco-peptides and glycoproteins with a clear focus on food and pharmaceutical chemistry. Therefore, these approaches combining the use of different catalytic systems, the improvement of tools such as immobilization technology, or chemical or genetic modification to improve the synthesization in the glycosylation process could be a very useful tool in a continuous biotechnological advance.

Mucin glycans are important component of the mucus barrier and vital defence against physical and chemical damage as well as pathogens. Abnormal expression of mucin glycans can lead to disease, especially cancer. Here, we first summarize the main types of glycosylation on mucins and the mechanisms by which abnormal mucin glycans occur. We next describe the role of ab-normal mucin glycans in cancer. Finally, we describe MUC1-based antibodies, vaccines, radio-pharmaceuticals, and CAR-T therapies using the best characterized MUC1 as an example.

Carbohydrates mediate a wide range of biological interactions, and understanding these processes benefits the development of new therapeutics. Isolating sufficient quantities of glycoconjugates from biological samples remains a significant challenge. With advances in chemical and enzymatic carbohydrate synthesis, the availability of complex carbohydrates is increasing and developing methods for stereoselective conjugation these polar head groups to proteins and lipids is critically important for pharmaceutical applications. The aim of this review is to provide an overview of commonly employed strategies for installing a functionalized linker at the anomeric position as well as examples of further transformations that have successfully led to glycoconjugation to vaccine constructs for biological evaluation as carbohydrate-based therapeutics.

The coevolution of species drives diversity in animals and plants and contributes to natural selection, whereas in host–parasite coevolution, a parasite may complete an incomplete evolutionary/developmental function by utilizing the host cell’s machinery. Analysis of related older data suggests that Plasmodium falciparum (P. falciparum), the pathogen of malaria tropica, cannot survive outside its human host because it is unable to perform the evolutionarily first protein glycosylation of serologically A-like, O-GalNAcα1-Ser/Thr-R, Tn antigen (“T nouvelle”) formation, owing to its inability for synthesizing the amino sugar N-acetyl-d-galactosamine (GalNAc). This parasite breaks the species barrier via hijacking the host's physiological A-like/Tn formation through abundantly expressing serine residues and creating hybrid A-like/Tn structures, which in the human blood group O(H) are attacked by the germline-encoded nonimmune polyreactive immunoglobulin M (IgM), exerting the highly anti-A/B/H-aggressive isoagglutinin activities. These activities physiologically undergo the ABO(H) blood group phenotype formation, occurring on the surfaces of red blood cells (RBC), epithelial and endothelial cells and on plasma proteins by identical glycosylation, performed by the ABO(H)-allelic glycotransferases, phenotypically downregulating the anti-A/B/H-reactive IgM (isoagglutinin) activities in the non-O blood groups. ABO(H) phenotype diversity, this way glycosidically linked and molecularly connected to humoral immunity, becomes exposed to the evolution.

Lemonomycin (1) was first isolated from the fermentation broth of Streptomyces candidus in 1964. The complete chemical structure was not elucidated until 2000 with extensive spectroscopic analysis. Lemonomycin is currently known as the only glycosylated tetrahydroisoquinoline antibiotic. Its potent antibacterial activity against Staphylococcus aureus and Bacillus subtilis and complex architecture make it an ideal target for total synthesis. In this short review, we summarize the research status of lemonomycin for biological activity, biosynthesis and chemical synthesis. The unique deoxy aminosugar-lemonose was proposed to play a crucial role in biological activity, as shown in other antibiotics, such as arimetamycin A, nocathiacin I, glycothiohexide α, and thiazamycins. Given the self-resistance of the original bacterial host, the integration of biosynthesis and chemical synthesis to pursue efficient synthesis and further derivatization is in high demand for the development of novel antibiotics to combat antibiotic-resistant infections.

The universal chirality is the commonly accepted view of nature. Biological chirality is the distinct part of the more general phenomena. Following this view, all living organisms are characterized by the non-equilibrium state of their molecular constituents. From the thermodynamic perspective, the non-equilibrium state of biomolecular ensemble holds inevitable consequences being the substrate of spontaneous reactions directed to equilibrium (not associated with life) state. At the protein level, spontaneous biological reactions represent the natural part of proteins' post-translational modifications (PTMs). The essential contribution to the origin and maintenance of the non-equilibrium state belongs to prevalent bio-molecular chirality. Correspondently, spontaneous PTMs such as racemization and glycation, working against life-supporting prevalent chirality, are known as the significant determinants of protein misfolding, dysfunctions, and aggregation. Accumulation of aberrant protein during life-span allows consideration of time-dependent spontaneous racemization and glycation as protein aging. Spontaneous PTMs of proteins is occurring in the interaction with other forms of enzymatic and non-enzymatic PTMs. In this review, we are considering the contribution of spontaneous racemization and non-enzymatic glycosylation to protein aging.

Novel treatment strategies are emerging for rare, genetic diseases, resulting in clinical trials that require adequate biomarkers for the assessment of the treatment effect. For enzyme defects, biomarkers that can be assessed from patient serum, such as enzyme activity, are highly useful, but the activity assays need to be properly validated to ensure a precise, quantitative measurement. Aspartylglucosaminuria (AGU) is a lysosomal storage disorder caused by the deficiency of the lysosomal hydrolase aspartylglucosaminidase (AGA). We have here established and validated a fluorometric AGA activity assay for human serum samples from healthy volunteers and AGU patients. We show that the validated AGA activity assay is suitable for the assessment of AGA activity in the serum of healthy controls and AGU patients, and it can be used for diagnostics of AGU and, potentially, for following a treatment effect.

N-glycosylation has been shown to affect the pharmacokinetic properties of several classes of biologics including monoclonal antibodies, blood factors, and lysosomal enzymes. In the last two decades, N-glycan engineering has been employed to achieve a N-glycosylation profile that is either more consistent or aligned with a specific improved activity (i.e. effector function or serum half-life). In particular, attention has focused on engineering processes in vivo or in vitro to alter the structure of the N-glycosylation of the Fc region of anti-cancer monoclonal antibodies in order to increase antibody-dependent cell-mediated cytotoxicity (ADCC). Here we applied the mannosidase I inhibitor kifunensine to the Nicotiana benthamiana transient expression platform to produce an afucosylated anti-CD20 antibody (rituximab). We determined the optimal concentration of kifunensine used in the infiltration solution, 0.375 µM, which was sufficient to produce exclusively oligomannose glycoforms, at a concentration 14 times lower than previously published levels. The resulting afucosylated rituximab revealed a 14-fold increase in ADCC activity targeting the lymphoma cell line Wil2-S when compared with rituximab produced in the absence of kifunensine. When applied to the cost-effective and scalable N. benthamiana transient expression platform, the use of kifunensine allows simple in-process glycan engineering without the need for transgenic hosts.

System xc-, the cystine/glutamate exchanger, is a membrane transporter that plays a critical role in the antioxidant response of cells. Recent work has shown that System xc- localizes to the plasma membrane during oxidative stress, allowing for increased activity to support production of glutathione. In this study, we used site-directed mutagenesis to examine the role of C-terminal lysine residues (K422, K472, K473) of xCT (SLC7A11) in regulating System xc-. We observed that K473R exhibits loss of transporter activity and membrane localization and is 7.5 kD lower in molecular weight, suggesting that K473 regulates System xc- trafficking and is modified under basal conditions. After ruling out ubiquitination and neddylation, we demonstrated that unlike WT xCT, K473R lacks N- and O-glycosylation and is sequestered in the endoplasmic reticulum. Next we demonstrated that K473Q, a constitutively acetylated lysine mimic, also exhibits loss of transporter activity, decreased membrane expression, and a 4 kD decrease in molecular weight, however, it is N- and O-glycosylated and localized to the endoplasmic reticulum and Golgi. These results suggest that acetylation and deacetylation of K473 in the endoplasmic reticulum and Golgi, respectively, serves to regulate the progression of the transporter through the biosynthetic pathway.

The aberrant glycosylation is a hallmark of cancer progression and chemoresistance. It is also an immune therapeutic target for various cancers. Tunicamycin (TM) is one of the potent nucleo-side antibiotics and an inhibitor of aberrant glycosylation in various cancer cells, including breast cancer, gastric cancer, and pancreatic cancer, parallel with inhibition of cancer cell growth and progression of tumors. Thus, TM can be considered a potent antitumor drug in various cancers and may promote chemosensitivity. Mechanistically, TM impedes the role of the UDP-HexNAc enzyme in the biosynthesis of oligosaccharides, specialized macromolecules instrumental in N-linked glycosylation. Further, like chemotherapies such as doxorubicin (DOX), 5'fluorouracil, etoposide, and Cisplatin, TM induces the unfolded protein response (UPR) by blocking aberrant glycosylation. Despite TM's antitumor effectiveness, its lack of cell-type specific cytotoxicity impedes its anticancer efficacy. Thus, various nanoencapsulation techniques and materials have been considered for use in experiments to reduce TM's cytotoxicity and improve efficacy as a targeted therapy. The current review is a profound audit of the benefits and pitfalls of TM in various cancers, focusing on breast, colon, and pancreatic cancers. Additional progressive studies have also discussed the use of TM in immune checkpoints and other unique pathways. Cytotoxicity and other possibly adverse effects of TM are highlighted based on the data from in vitro and in vivo assays. In addition, the recent advances in nano-based drug delivery systems regarding TM have been emphasized. However, the potential of this nucleoside inhibitor re-quires thorough investigation and research to determine its likeliness as a viable chemotherapeutic.

Aberrant glycosylation affects cancer progression and immune evasion. Approximately 15% of colorectal cancers (CRCs) demonstrate microsatellite instability (MSI) and display major differences in outcomes and therapeutic responses as compared to corresponding microsatellite stable (MSS) tumors. We compared the N-glycan profiles of stage II and IV MSI CRC tumors, further subdivided into BRAFV600E wild-type and mutated subgroups (n=10 in each subgroup), with each other and with those of paired non-neoplastic mucosal samples using mass spectrometry. Further, the N-glycans of BRAFV600E wild-type stage II MSI tumors were compared to corresponding MSS tumors (n=9). Multiple differences in N-glycan profiles were identified between MSI CRCs and control tissues, as well as between stage II MSI and MSS samples. MSI CRC tumors showed a lower relative abundance of high-mannose N-glycans than the control tissues or the MSS CRCs. Among MSI CRC subgroups, acidic N-glycans showed tumor stage and BRAF mutation status dependent variation. Especially large, sulfated/phosphorylated, and putative terminal N-acetylhexosamine containing acidic N-glycans differed between the MSI CRC subgroups, showing opposite changes in stage II and IV, when comparing BRAF mutated and wild-type tumors. Our results show that molecular subgroups of CRC have characteristic glycan profiles that may explain certain carcinogenic properties of MSI tumors.

The 2019 novel SARS-like coronavirus (SARS-CoV-2) entry depends on the host membrane serine protease TMPRSS2, which can be blocked by some clinically-proven drugs. Here we analyzed spatial relevance between glycosylation sequons and antibody epitopes and found that, different from SARS-CoV S, most high-surface-accessible epitopes of SARS-CoV-2 S are blocked by the glycosylation, and the optimal epitope with the highest surface accessibility is covered by the S1 cap. TMPRSS2 inhibitor treatments may prevent unmasking of this epitope and therefore prolong virus clearance and may induce antibody-dependent enhancement. Interestingly, a heparin-binding sequence immediately upstream of the S1/S2 cleavage site has been found in SARS-CoV-2 S but not in SARS-CoV S. Binding of SARS-CoV-2 with heparins may lead to exposure of S686, which then facilitates the S1/S2 cleavage, induces exposure of the optimal epitope, and therefore increases the antibody titres. A combination of heparin and vaccine (or convalescent serum) treatments thus is recommended.

Monitoring glycosylation changes within cells upon response to stimuli remains challenging because of the complexity of this large family of post-translational modifications (PTMs). We have developed an original tool enabling labeling and visualization of the cell cycle key-regulator b-catenin in its O-GlcNAcylated form based on intramolecular Förster resonance energy transfer (FRET) technology in cells. We opted for a bioorthogonal chemical reporter strategy based on the dual-labeling of b-catenin with a green fluorescent protein (GFP) for protein sequence combined with a chemically-clicked imaging probe for PTM resulting in a fast and easy to monitor qualitative FRET assay. We validated this technology by imaging the O-GlcNAcylation status of b-catenin in HeLa cells. Moreover, the changes in O-GlcNAcylation of b-catenin were varied by perturbing global cellular O-GlcNAc levels with inhibitors of O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). Finally, we provided a flowchart demonstrating how this technology is transposable to any kind of glycosylation.

The traditional Chinese drug Bombyx Batryticatus mori.L (BBm) which is also named the white stiff silkworm has been widely used in Chinese clinics for thousands of years. It is famous for its antispasmodic and blood circulation promoting effects. Cardiomyocyte hypertrophy, interstitial cell hyperplasia and myocardial fibrosis are closely related to the N-glycosylation of key proteins. To examine the alterations of N-glycosylation that occur in diabetic myocardium during the early stage of the disease and clarify the therapeutic effect of 1-DNJ extracted from BBm, we used the db/db mouse model and an approach based on hydrophilic chromatography solid-phase extraction integrated with an LC-MS/MS identification strategy to perform a site-specific N-glycosylation analysis of left ventricular cardiomyocyte proteins. AGEs, hydroxyproline, CTGF and other serum biochemical indicators were measured with ELISA. In addition, the α1,6-fucosylation of N-glycans was profiled with LCA lectin blots and FITC-labelled lectin affinity histochemistry. The results indicated that 1-DNJ administration obviously downregulated myocardium protein N-glycosylation in db/db mice. The expression levels of serum indicators and fibrosis-related cytokines were reduced significantly by 1-DNJ in a dose-dependent manner. The glycan α1,6-fucosylation level of the db/db mouse myocardium was elevated, and the intervention effect of 1-DNJ administration on N-glycan α1,6-fucosylation was significant. To verify this result, the well-known TGF-β/smad2/3 pathway was selected, and core α1,6-fucosylated TGFR-βⅡ was analysed semi-quantitatively with western blotting. The result supported the conclusions obtained from LCA lectin affinity histochemistry and lectin blot analysis. The expression level of FUT8 mRNA was also detected, and the results showed that 1-DNJ administration did not cause obvious inhibitory effects on FUT8 expression. Therefore, the mechanism of 1-DNJ to relieve the DCM-associated fibrosis can be concluded as the inhibition of N-GlcNAc formation and the reduction of substrate concentration.

. Protein cysteine S-glycosylation is a relatively rare and less well characterized post-translational modification (PTM). Creating reliable model proteins that carry this modification is challenging. The lack of available model or natural S-glycosylated proteins significantly hampers the development of MS-based methodologies for detecting protein cysteine S-glycosylation in real-world proteomic studies. There is also limited MS-sequencing data describing easier to create synthetic S-glycopeptides. Here, we present the results of an in-depth manual analysis of automatically annotated CID/HCD spectra for model S-glucopeptides. The CID spectra show a long series of y/b-fragment ions with retained S-glucosylation, regardless of the dominant m/z signals corresponding to neutral loss of 1,2-anhydroglucose from the precursor ions. In addition, the spectra show signals manifesting glucosyl transfer from the cysteine position onto Lys, Arg side chains, and a peptide N-terminus. Other spectral evidence indicates that the N-glucosylated initial products of transfer are converted into N-furanosylated (i.e., glycated) structures due to Amadori rearrangement. We discuss the peculiar transfer of the glucose oxocarbenium ion (Glc+) to positively charged guanidinium residue (ArgH+) and propose a mechanism for the gas-phase Amadori rearrangement involving a hydride ion shift.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the novel coronavirus responsible for the coronavirus disease 2019 (COVID-19) pandemic, represents a serious threat to public health. The spike (S) glycoprotein of SARS-CoV-2 mediates viral entry into host cells and is heavily glycosylated. In this study, we systemically analyzed the roles of 22 putative N-linked glycans in SARS-CoV-2 S protein expression, membrane fusion, viral entry, and stability. Using α-glycosidase inhibitors, castanospermine and NB-DNJ, we confirmed that disrupting the N-linked glycosylation process blocked the maturation of the S protein, leading to impairment of S protein-mediated membrane fusion. Single substitution of each of the 22 N-linked glycosylation sites with glutamine revealed that 9 out of the 22 N-linked glycosylation sites were critical for S protein folding and maturation, resulting in reduced S protein-mediated cell-cell fusion and viral entry. Of note, N1074Q mutation markedly affected S protein stability and induced significant receptor-independent syncytium (RIS) formation in HEK293T/hACE2-KO cells, and removal of the furin-cleavage site partially compensated instability of N1074Q mutation. Although the corresponding mutation in the SARS-CoV S protein (N1056Q) did not induce RIS in HEK293T cells, the mutants N669Q and N1080Q exhibited increased fusogenic activity and induced syncytia formation in HEK293T cells. Therefore, N-glycans on the SARS-CoV and SARS-CoV-2 S2 subunits are of great importance in maintaining the prefusion state of the S protein. The study revealed the critical roles of N-glycans in S protein maturation and stability, which have implications for the design of vaccines and anti-viral strategies.

The Severe acute respiratory syndrome-Corona virus-2 (SARS-CoV-2) which is responsible for recurring pandemics takes advantage of host-cell processes including the glycosylation pathway. The heavily glycosylated spike protein assists viruses in attachment and penetration. The N-glycans of N-terminal domain N165 and N234 play a significant role in conformational dynamics of the receptor-binding domain (RBD) with angiotensin-converting enzyme 2 (ACE2). In addition, the deletion of N-glycan sites N331 and N334 have been associated with reduced infectivity. This signifies the importance of targeting the N-glycans making them unavailable for interacting with the ACE2 receptor, ultimately leading to reduced infectivity. These glycans can be specifically targeted and can be used for designing SARS specific drugs or neutralizing molecules. In the current study, lectins Griffithsin, Cyanovirin-N, Cyanovirin homolog, and BanLec H84T were used to target the spike protein's N-glycans. Molecular docking programs AutoDock Vina and HADDOCK were used to study lectin-glycan interactions. The interactions look convincible in accordance with the lowest interaction energies best-fit approach but the characteristic feature (scoring functions) of the docking programs are questionable concerning Lectin-Glycan interactions exist in nature. There is a high need of the hour for developing specific algorithms for docking glycans with a preferential selection of terminal residues.

The Chinese drug Bombyx Batryticatus mori.L which also named as the white stiff silkworm is widely used in clinics, due to the significant antispasmodic and promotional blood circulation effects. In addition, its hypoglycemic effect is also recognized in recent years. From a pathological point of view, the enzymatic glycosylation and non-enzymatic glycation both have important roles in regulating properties of proteins and are associated with Diabetes. With the db/db mouse model, we examined the alterations of N-glycosylation of diabetic myocardium at primary stage and clarify the differences in glycosylation of myocardium before and after with 1-DNJ treatment. Hydrophilic chromatography solid phase extraction enrichment and LC-MS/MS identification was applied to profile the alternations in protein glycosylation. Meanwhile, N-glycan α1, 6-fucosylation alterations were profiled with LCA lectin blot and FITC-labelled lectin affinity histochemistry. Our results showed that AGES, hydroxyproline, CTGF and other serum indicators and fibrosis related cytokines expressional levels were reduced significantly by 1-DNJ in a dose-dependent manner. In order to verify this result, the well-known pathway of TGF-β/smad2/3 was picked out and α1, 6-core fucosylated TGFR-βⅡwas semi-quantified with western blot method. The result sustained the conclusion from LCA lectin affinity histochemistry and lectin blot analysis. The expressional level of α1, 6-fucosyltransferase mRNA was increased in the myocardium of db/db mice, however, the 1-DNJ administration did not show obvious inhibitory effect on FU8 expression. This unexpected result can be interpreted as 1-DNJ plays the roles by reducing the concentration of substrate rather than inhibiting α1，6-fucose glycosyltransferase expression. Meanwhile, 1-DNJ crude extract from BBm with some flavonoids accompany can also play the roles of anti-oxidant, and all the chemicals protect the diabetic myocardium from hyperglycemia damage commonly.

Post-translational modifications (PTMs) represent a cornerstone in the complexity of the proteome, significantly contributing to diversifying protein structure and function. PTMs can significantly influence protein function, stability, localization, and interactions with other molecules. Therefore, it is important when choosing a protein expression system to ensure the precise incorporation of PTMs during protein synthesis, which is paramount for producing biologically active proteins. Cell-free protein synthesis (CFPS) system has emerged as a powerful protein synthesis platform and research toolkit in synthetic biology. The open nature of the system allows the reaction environment to be tailored to any protein of interest to promote specific PTMs, thus allowing for the production of a protein with the desired modifications. This review presents various PTMs achieved in the CFPS systems, providing insights into the current challenges, successes, and future prospects.

Glycosylation is a complex post-translational modification that conveys functional diversity to glycoconjugates. Cell surface glycosylation mediates several biological activities such as induction of intracellular signaling pathway and pathogen recognition. Red blood cell (RBC) membrane N-glycans determine blood type and influence cell lifespan. Although several proteomic studies were carried out, glycosylation of RBC membrane proteins has not been systematically investigated. This work aims at exploring the human RBC N-glycome by high-sensitivity MALDI-MS techniques to outline a fingerprint of RBC N-glycans. To this purpose, MALDI-TOF spectra of healthy subjects harboring different blood groups were acquired. Results showed the predominant occurrence of neutral and sialylated complex N-glycans with bisected N-acetylglucosamine, core- and/or an-tennary fucosylation. In the higher mass region these species presented with multiple N-acetyllactosamine repeating units. Amongst the detected glycoforms, the presence of glycans bearing ABO(H) antigens allowed us to define a distinctive spectrum for each blood group. For the first time, advanced glycomic techniques have been applied to a comprehensive exploration of human RBC N-glycosylation, providing a new tool for the early detection of distinct glycome changes associated with disease conditions as well as to understand pathogens molecular recognition.

The production and N-glycosylation of recombinant human butyrylcholinesterase (BChE), a model highly glycosylated therapeutic protein, in a transgenic rice cell suspension culture treated with kifunensine, a strong α-mannosidase I inhibitor, was studied in a 5 L bioreactor. A media exchange was performed at day 7 of cultivation by removing spent sugar rich media (NB+S) and adding fresh sugar free (NB-S) media to induce the rice α-amylase 3D (RAmy3D) promoter to produce rice recombinant human BChE (rrBChE). Using a 1.25X concentrated sugar-free medium together with an 80% reduced working volume during the media exchange lead to a total active rrBChE production level of 79 ± 2 µg (g FW)^-1 or 7.5 ± 0.4 mg L^-1 in the presence of kifunensine, which is 1.5-times higher than our previous bioreactor runs using normal sugar free medium with no kifunensine treatment. Importantly, the amount of secreted active rrBChE in culture medium was enhanced in the presence of kifunensine, comprising 44% of the total active rrBChE at day 5 post-induction. Coomassie stained SDS-PAGE gel and Western blot analyses reveal different electrophoretic migration of purified rrBChE bands with and without kifunensine treatment, which is attributed to different N-glycoforms. N-Glycosylation analysis shows substantial increase of oligomannose glycans (Man5/6/7/8) in rrBChE treated with kifunensine compared to controls. However, mass transfer limitation of kifunensine is likely the major reason for incomplete inhibition of α-mannosidase I in this bioreactor study.

Type III interferon (IFN-λs) exhibit potent antiviral activity and immunomodulatory effects in specific cells. Nucleotide fragements of bovine ifn-λ (boifn-λ) gene was synthetized after codon optimization. The boifn-λ gene was then amplified by splicing by overlap extension PCR (SOE PCR), resulting in serendipitous acquisition of the mutated boIFN-λ3V18M. Recombinant plasmids pPICZαA-boIFN-λ3/λ3V18M were constructed and the corresponding proteins were expressed in Pichia pastoris with high-level extracellular soluble form. Dominant expression strains of boIFN-λ3/λ3V18M were selected by Western blot and ELISA, cultured on a large scale, and the recombinant proteins purified by ammonium sulphate precipitation and ion exchange chromatography, yielding 1.5g/L and 0.3 g/L, with 85% and 92% purity, respectively. The antiviral activities of boIFN-λ3/λ3V18M exceeded 106 U/mg, were neutralized with IFN-λ3 polyclonal antibodies, were susceptible to trypsin, and retained stability within defined pH and temperature ranges. Furthermore, boIFN-λ3/λ3V18M exerted antiproliferative effects on MDBK cells without cytotoxicity at 104 U/mL. Overall, boIFN-λ3 and boIFN-λ3V18M did not differ substantially in biological activity, except for reduced glycosylation of the latter. Development of boIFN-λ3 and comparative evaluation with the mutant provide theoretical insights into antiviral mechanisms of boIFN-λs and provide material for therapeutic development.

Over recent decades, therapeutic proteins have had widespread success in treating a myriad of diseases. Glycosylation, a near universal feature of this class of drugs, is a critical quality attribute that significantly influences the physical properties, safety profile and biological activity of therapeutic proteins. Optimizing protein glycosylation, therefore, offers an important avenue to developing more efficacious therapies. In this review, we discuss specific examples of how variations in glycan structure and glycoengineering impacts the stability, safety, and clinical efficacy of protein-based drugs that are already in the market as well as those that are still in preclinical development. We also highlight the impact of glycosylation on next generation biologics such as T cell-based cancer therapy and gene therapy.

The cytosolic PNGase (peptide:N-glycanase; Png1 in yeast; NGLY1/Ngly1 in human/mice), also known as peptide-N4-(N-acetyl-beta-glucosaminyl)-asparagine ami-dase, is a well-conserved deglycosylation enzyme (EC 3.5.1.52) which catalyzes the non-lysosomal hydrolysis of an N(4)-(acetyl-β-D-glucosaminyl) asparagine residue into N-acetyl-β-D-glucosaminylamine and a peptide containing an aspartate residue. This enzyme (NGLY1) plays essential roles in clearance of misfolded or unassembled gly-coproteins through a process named ER-associated degradation (ERAD). Accumulating evidence also points out that NGLY1 deficiency can cause an autosomal recessive hu-man genetic disorder associated with abnormal development and congenital disorder of deglycosylation. In addition, the loss of NGLY1 can affect multiple cellular pathways, including but not limited to NFE2L1 pathway, Creb1/Atf1-AQP pathway, BMP path-way, AMPK pathway, and SLC12A2 ion transporter, which might be the underlying reasons for a constellation of clinical phenotypes of NGLY1 deficiency. The current comprehensive review indeed uncovers the detailed NGLY1’s structure and its im-portant roles for participation in ERAD, involvement in CDDG and potential treatment for NGLY1 deficiency.

The RV144 trial represents the only vaccine trial to demonstrate any protective effect against HIV-1 infection. While the reason(s) for this protection are still being evaluated, it serves as justification for widespread efforts aimed at developing new, more effective HIV-1 vaccines. Advances in our knowledge of HIV-1 immunogens and host antibody responses to these immunogens are crucial to informing vaccine design. While the envelope (Env) protein is the only viral protein present on the surface of virions, it exists in a complex trimeric conformation and is decorated with an array of variable N-linked glycans, making it an important but difficult target for vaccine design. Thus far, efforts to elicit a protective humoral immune response using structural mimics of native Env trimers have been unsuccessful. Notably, the aforementioned N-linked glycans serve as a component of many of the epitopes crucial for the induction of potentially protective broadly neutralizing antibodies (bnAbs). Thus, a greater understanding of Env structural determinants, most critically Env glycosylation, will no doubt be of importance in generating effective immunogens. Recent studies have identified the HIV-1 Env signal peptide (SP) as an important contributor to Env glycosylation. Further investigation into the mechanisms by which the SP directs glycosylation will be important, both in the context of understanding HIV-1 biology and in order to inform HIV-1 vaccine design.

Astroviruses (AstVs) are occurs globally and are common causes of gastroenteritis in human and animals. The genetic diversity and epidemiology of AstVs in Africa is not well known, hence, we aimed to genetically characterize astroviruses in asymptomatic smallholder piglets in East Africa. Twenty-four samples randomly selected from 446 piglets (<6 months old), initially collected for rotavirus study, was sequenced for metagenomic analysis. Thirteen (13/24) samples had contigs with high identity to genus Mamastrovirus. Analysis of 7 strains with complete (or near complete) genome revealed variable nucleotide and amino acid sequence identities with known PoAstV strains. The U083 and K321 strains had nucleotide sequence similarities ranging from 66.4 to 75.4 % to the known PoAstV2 strains, nucleotide sequence similarity of U460 strain with known PoAstV3 ranged 57.0 to 65.1 % to the, while K062, K366, K451, and K456 strains showed nucleotide sequence similarities of 63.5 to 80 % to the known PoAstV4 strains. The low sequence identities (<90 %) indicate that novel genotypes of PoAstVs are circulating in the study area. Multiple recombination events were detected in our PoAstV4 strains, indicating that the genetic diversity observed in these strains may be due to recombination. Importantly, we identified potential candidate epitopes with conserved peptides in our PoAstV strains that could aid in the design of immune diagnosis tools and subunit vaccines. Our data provide new intuitions into the genetic structure of porcine astroviruses in East African.

Age-related macular degeneration, a leading cause of visual loss and dysfunction in the devel-oped world, is a disease initiated by genetic polymorphisms that impairs negative regulation of complement. Proteomic investigation points to altered glycosylation and loss of SIGLEC medi-ated glyco-immune checkpoint parainflammatory homeostasis as a main determinant for the vi-sion impairing complications of macular degeneration. The effect of altered glycosylation on microglial maintained retinal para-inflammatory homeostasis and eventual recruitment and polarization of peripheral blood monocyte derived macrophages (PBMDM) into the retina can explain the phenotypic variability seen in this clinically heterogenous disease. Restoring gly-co-immune checkpoint control with a sialic acid mimetic nanoparticle targeting microgli-al/macrophage SIGLECs to regain retinal para inflammatory homeostasis is a promising thera-peutic that could halt the progression of and improve visual function in all stages of macular de-generation.

A critical quality attribute of therapeutic monoclonal antibodies (mAbs) is the terminal sugar molecules of the N-linked glycan attached to the fragment crystalizable (Fc) region. There exists naturally-occurring heterogeneity in the N-linked glycan structure of mAbs, and such heterogeneity has a significant influence on the clinical safety and efficacy of mAb drugs. We previously proposed a constraint-based modeling method called glycosylation flux analysis (GFA) to characterize the rates (fluxes) of intracellular glycosylation reactions and applied the method to examine the N-linked glycosylation of immunoglobulin G (IgG) in fed-batch Chinese hamster ovary (CHO) fed-batch cultivations. In this work, we significantly improved the computational efficiency of the GFA, and employed the method to analyze the glycosylation of IgG in continuous perfusion CHO cultivations. Perfusion cell cultures have several advantages over the traditional (fed-)batch operation, including higher productivity per unit volume of reactor and more consistent product quality. The GFA showed that as in the fed-batch cultivation, the dynamical changes of IgG glycan heterogeneity in the perfusion culture are mainly attributed to alterations in the galactosylation flux activity. Furthermore, a regression analysis of the galactosylation flux activity using random forest regression linked the dynamics of galactosylation activity with the cell-specific productivity of IgG and the extracellular ammonia concentration.

In plant cells the conventional route to the vacuole involves the endoplasmic reticulum, the Golgi and the prevacuolar compartment. However, over the years, unconventional sorting to the vacuole, bypassing the Golgi, has been described, which is the case of the Plant Specific Insert (PSI) of the aspartic proteinase cardosin A. Interestingly, this Golgi-bypass ability is not a characteristic shared by all PSIs, since two related PSIs showed to have different sensitivity to ER-to-Golgi blockage. Given the high sequence similarity between the PSIs domains, we sought to depict the differences in terms of post-translational modifications. In fact, one feature that draws our attention is that one is N-glycosylated and the other one is not. Using site-directed mutagenesis to obtain mutated versions of the two PSIs, with and without the glycosylation motif, we observed that altering the glycosylation pattern interferes with the trafficking of the protein as the non-glycosylated PSI-B, unlike its native glycosylated form, is able to bypass ER-to-Golgi blockage and accumulate in the vacuole. This is also true when the PSI domain is analyzed in the context of the full-length cardosin. Regardless of opening exciting research gaps, the results obtained so far need a more comprehensive study of the mechanisms behind this unconventional direct sorting to the vacuole.

Congenital Disorders of Glycosylation (CDG) are a heterogenous group of primarily autosomal recessive mendelian diseases caused by disruptions in the synthesis of lipid linked oligosaccha-rides and their transfer to proteins. CDGs affect multiple organ systems and vary in presentation, even within families. Here we describe a chemically induced mouse mutant, tvrm76, with early onset photoreceptor degeneration. The recessive mutation was mapped to Chromosome 9 and as-sociated with a missense mutation in the Dpagt1 gene encoding UDP-N-acetyl-D-glucosamine:dolichyl-phosphate N-acetyl-D-glucosaminephosphotransferase (EC 2.7.8.15). The mutation is predicted to cause a substitution of aspartic acid with glycine at residue 166 of DPAGT1. Increased expression of Ddit3, and elevated levels of HSPA5 (BiP) sug-gest the presence of early-onset endoplasmic reticulum (ER) stress. These changes were associated with induction of photoreceptor apoptosis in tvrm76 retinas. Mutations in human DPAGT1 cause Myasthenic Syndrome 13 and severe forms of Congenital Disorder of Glycosylation Type Ij. In contrast, Dpagt1tvrm76 homozygous mice present with congenital photoreceptor degeneration without overt muscle or muscular junction involvement. Our results suggest the possibility of DPAGT1 mutations in human patients that present primarily with retinitis pigmentosa with little or no muscle disease. Variants in DPAGT1 should be considered when evaluating cases of non-syndromic retinal degeneration.

While the angiotensin converting enzyme 2 (ACE2) protein is defined as the primary severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor, the viral serine molecule might be mobilized by the host's transmembrane protease serine subtype 2 (TMPRSS2) enzyme from the viral spike (S) protein and hijack the host’s N-acetyl-D-galactosamine (GalNAc) metabolism. The resulting hybrid, serologically A-like/Tn (T-nouvelle) structure potentially acts as a host–pathogen functional molecular bridge. In humans, this intermediate structure will hypothetically be replaced by ABO(H) blood group-specific, mucin-type structures, in the case of infection hybrid epitopes, implicating the phenotypically glycosidic accommodation of plasma proteins. The virus may, by mimicking the synthetic pathways of the ABO(H) blood groups, bind to the cell surfaces of the blood group O(H) by formation of a hybrid H-type antigen as the potential precursor of hybrid non-O blood groups, which does not affect the highly anti-glycan aggressive anti-A and anti-B isoagglutinin activities, exerted by the germline-encoded nonimmune immunoglobulin M (IgM). In the non-O blood groups, which have developed from the H-type antigen, these IgM activities are downregulated by phenotypic glycosylation, while adaptive immunoglobulins might arise in response to the hybrid A and B blood group structures, bonds between autologous carbohydrates and foreign peptides, suggesting the exertion of autoreactivity. The non-O blood groups thus become a preferred target for the virus, whereas blood group O(H) individuals, lacking the A/B phenotype-determining enzymes and binding the virus alone by hybrid H-type antigen formation, have the least molecular contact with the virus and maintain the critical anti-A and anti-B isoagglutinin activities, exerted by the ancestral IgM, which is considered the humoral spearhead of innate immunity.

Glycosylation, a prevalent post-translational modification, plays a pivotal role in regulating intricate cellular processes by covalently attaching glycans to macromolecules. Dysregulated glycosylation is linked to a spectrum of diseases, encompassing cancer, neurodegenerative disorders, congenital disorders, infections, and inflammation. This review delves into the intricate interplay between glycosylation and protein conformation, with a specific focus on the profound impact of N-glycans on the selection of distinct protein conformations, characterized by distinct interactomes – namely protein assemblies - under normal and pathological conditions across various diseases. We begin by examining the spike protein of the SARS virus, illustrating how N-glycans regulate the infectivity of pathogenic agents. Subsequently, we utilize the prion protein and the chaperone glucose-regulated protein 94 as examples, exploring instances where N-glycosylation transforms physiological protein structures into disease-associated forms. Unraveling these connections provides valuable insights into potential therapeutic avenues and a deeper comprehension of the molecular intricacies that underlie disease conditions. This exploration of glycosylation's influence on protein conformation effectively bridges the gap between the glycome and disease, offering a comprehensive perspective on the therapeutic implications of targeting conformational mutants and their pathologic assemblies in various diseases. The goal is to unravel the nuances of these post-translational modifications, shedding light on how they contribute to the intricate interplay between protein conformation, assembly and disease.