Preprint Article Version 6 Preserved in Portico This version is not peer-reviewed

The Structure of the Membrane Protein of SARS-CoV-2 Resembles the Sugar Transporter semiSWEET

Version 1 : Received: 28 April 2020 / Approved: 29 April 2020 / Online: 29 April 2020 (14:06:19 CEST)
Version 2 : Received: 3 May 2020 / Approved: 4 May 2020 / Online: 4 May 2020 (18:14:23 CEST)
Version 3 : Received: 19 May 2020 / Approved: 20 May 2020 / Online: 20 May 2020 (04:43:42 CEST)
Version 4 : Received: 18 July 2020 / Approved: 19 July 2020 / Online: 19 July 2020 (15:06:53 CEST)
Version 5 : Received: 19 August 2020 / Approved: 20 August 2020 / Online: 20 August 2020 (13:47:23 CEST)
Version 6 : Received: 17 October 2020 / Approved: 19 October 2020 / Online: 19 October 2020 (10:48:05 CEST)

A peer-reviewed article of this Preprint also exists.

Thomas, S. The Structure of the Membrane Protein of SARS-CoV-2 Resembles the Sugar Transporter SemiSWEET. Pathogens and Immunity. 2020;5(1):342-363. Thomas, S. The Structure of the Membrane Protein of SARS-CoV-2 Resembles the Sugar Transporter SemiSWEET. Pathogens and Immunity. 2020;5(1):342-363.


Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the disease COVID-19 that has decimated the health and economy of our planet. The virus causes the disease not only in people but also in companion and wild animals. People with diabetes are at risk of the disease. As yet we do not know why the virus is highly successful in causing the pandemic within 3 months of its first report. The structural proteins of SARS include, membrane glycoprotein (M), envelope protein (E), nucleocapsid protein (N) and the spike protein (S). The structure and function of the most abundant structural protein of SARS-CoV-2, the membrane (M) glycoprotein is not fully understood. Using in silico analyses we determined the structure and potential function of the M protein. The M protein of SARS-CoV-2 is 98.6% similar to the M protein of bat SARS-CoV, maintains 98.2% homology with pangolin SARS-CoV, and has 90% homology with M protein of SARS-CoV; whereas, the similarity was only 38% with the M protein of MERS-CoV. In silico analyses showed that the M protein of SARS-CoV-2 has a triple helix bundle, form a single 3-transmembrane domain (TM), and are homologous to the prokaryotic sugar transport protein semiSWEET. SemiSWEETs are related to the PQ-loop family that function as cargo receptors in vesicle transport, mediates movement of basic amino acids across lysosomal membranes, and is also involved in phospholipase flippase function. The advantage and role of the M protein having a sugar transport-like structure is not clearly understood. The M protein of SARS-CoV-2 interacts with S, E and N protein. The S protein of the virus is glycosylated. It could be hypothesized that the sugar transporter-like structure of the M protein influences glycosylation of the S protein. Endocytosis is critical for the internalization and maturation of RNA viruses, including SARS-CoV-2. Sucrose is involved in endosome and lysosome maturation and may also induce autophagy, pathways that help in the entry of the virus. Overall, it could be hypothesized that the semiSWEET sugar transporter-like structure of the M protein may be involved in multiple functions that may aid in the rapid proliferation, replication and immune evasion of the SARS-CoV-2 virus. Biological experiments would validate the presence and function of the semiSWEET sugar transporter.


SARS-CoV-2; COVID-19; Coronavirus; Virus; sugar transporter; SemiSWEET; Membrane glycoprotein, Pandemic


Biology and Life Sciences, Virology

Comments (1)

Comment 1
Received: 19 October 2020
Commenter: Sunil Thomas
Commenter's Conflict of Interests: Author
Comment: I have updated the manuscript
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