Dark Proteome of Newly Emerged SARS-CoV-2 in Comparison with Human and Bat Coronaviruses

Rajanish Giri; Taniya Bhardwaj; Meenakshi Shegane; Bhuvaneshwari R. Gehi; Prateek Kumar; Kundlik Gadhave

The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020.03.13.990598 doi: bioRxiv preprint MSA results illustrate ( Figure 4B ) that this protein is highly conserved, with only three amino acid substitutions in E protein of SARS-CoV-2 conferring its 96% sequence similarity with Human SARS and Bat CoV. Bat CoV shares 100% sequence identity with Human SARS. Mean PPID calculated for SARS-CoV-2, Human SARS, and Bat CoV E proteins are 5.33%, 6.58%, and 6.58% respectively ( Table 1) . The E protein is found to have a reasonably well-predicted structure. Our predictions suggest that the residues of N-and C-terminals are displaying a higher tendency for the disorder. The last 18 hydrophilic residues (residues 59-76) have been reported to adopt a random-coil conformation with and without the addition of lipid membranes [64] . Literature suggests that the last four amino acids of the C-terminal region of E protein containing a PZD-binding motif are involved in protein-protein interactions with a tight junction protein PALS1. Our results support literature as we identified long N-terminal region of approximately 30 residues long as disorder-based protein binding region in all three viruses (see Table 2, Supplementary Table 7 and 8). PALS1 is involved in maintaining the polarity of epithelial cells in mammals [65] . Respective graphs in Figures 4C, 4D , and 4E show the predicted intrinsic disorder profiles for E proteins of SARS-CoV-2, Human SARS, and Bat CoV. We speculate that the disordered region content may be facilitating the interactions with other proteins as well. In agreement with this hypothesis, Table 2 shows that in E protein from SARS-CoV-2, the C-terminal domain author/funder. All rights reserved. No reuse allowed without permission.