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The copyright holder for this preprint (which was not peer-reviewed) is the .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 Non-structural protein 16 (Nsp16). Nsp16 protein is another MTase domain-containing protein. As methylation of coronavirus mRNAs occurs in steps, three proteins Nsp10, Nsp14, and Nsp16 acts one after another. The first event requires the initiation trigger from Nsp10 protein, after which Nsp14 methylates capped mRNAs forming cap-0 (7Me) GpppA-RNAs. Nsp16 protein, along with its co-activator protein Nsp10, acts on cap-0 (7Me) GpppA-RNAs to give rise to final cap-1 (7Me)GpppA(2'OMe)-RNAs [149, 157] . A 2 Å X-ray crystal structure of the Human SARS nsp10-nsp16 complex is depicted in Figure 33D (PDB ID: 3R24) [158] . The structure consists of a characteristic fold present in class I MTase family comprising of α-helices and loops surrounding a seven-stranded β-sheet [158] . Nsp16 protein of SARS-CoV-2 is found to be equally similar to Nsp16s from Human SARS and Bat CoV (93.29%) (Supplementary Figure S2I) . Mean PPIDs for Nsp16s from SARS-CoV-2, Human SARS, and Bat CoV are 5.37%, 3.02%, and 3.02%, respectively. In line with these PPIDs values, Figures 33A, 33B, and 33C show that Nsp16s are mostly ordered author/funder. All rights reserved. No reuse allowed without permission.