Bioinformatics analysis on structure and function of the spike glycoprotein of SARS-CoV-2 and its prokaryotic expression

ABSTRACT

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV -2) is a highly pathogenic and rapidly spreading pathogen. It can invade and infect cells by recognizing receptors on the surface of host cells with spike (5) glycoprotein. Systematic bioinformatics analysis and prokaryotic expression of the S protein can aid understanding of its function and clarify the molecular mechanism of viral infection mediated by this protein. The physicochemical properties, subcellular localization, post - translational modifications and protein - interaction network of the S protein were analyzed systematically using Protparam. Pfam, TMHMM ExPASy - ProtScale, PSORT II, SignalP, UniProt, NetPhos 3.1. NetNGlyc 1.0, NetOGlyc 4.0. BLAST and other bioinformatics software and databases. In addition. Clustal X2 and MEGA7.0 were used to analyze the homology and phylogeny of S glycoproteins based on amino-acid sequences. Finally, recombinant expression vector of the S glycoprotein was constructed by molecular cloning technology and expressed in Escherichia call. Results showed that the S glycoprotein is composed of 1,273 amino acids, with a molecular weight of 141.2 kD and an isoelectric point of 6.24. It had two coiled helical structures and one transmembrane helix region. It was a hydrophobic protein, contained a spike receptor-binding domain and 52 glycoprotein domain. This protein was distributed mainly in the endoplasmic-reticulum membrane (39.1%) and cell membrane (21.7%) of host cells. and contained 136 potential phosphorylation sites and 20 possible glycosylation sites. SARS-CoV, SARS-Coy WI-120 and bat coronavirus HKU3 showed the highest sequence identity with the spike-glycoprotein sequence of SARS-CoV-2 (76%). SARS-CoV-2, SARS-CoV and bat coronavirus clustered into a large branch. suggesting that they may have a common ancestor. The S protein was expressed mainly in the precipitate after centrifugation of bacterial lysates, which lays a foundation for future structural analysis and vaccine development. The S glycoprotein was highly conserved between SARS-CoV and bat coronavirus, suggesting that this glycoprotein has a vital role in viral invasion into host cells. SARS-CoV-2 may have a common ancestor with SARS-CoV and bat coronavirus. Our study provides an important data basis for expression. purification. structural and functional analysis of the S glycoprotein of SARS-CoV-2. Our data may help to reveal the biological functions of the S glycoprotein, and provide a scientific basis for the design and screening of new antiviral drugs targeting this protein.