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The copyright holder for this preprint (which was not peer-reviewed) is the .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 On performing MSA, results of which are shown in Figure 7D , we found that ORF3a protein from SARS-COV-2 is slightly evolutionary closer to the ORF3a of Bat CoV (73.36%) than to the ORF3a of Human SARS CoV (72.99%). Graphs in Figures 7A, 7B , and 7C depict the propensity for disorder in ORF3a proteins of novel SARS-CoV-2, Human SARS CoV, and Bat CoV (SARS-like), respectively. Mean PPIDs in these ORF3a proteins are 9.1% (SARS-CoV-2), 8.8% (Human SARS), and 6.2% (Bat CoV (SARS-like)). ORF3a of SARS CoV-2 shows protein-binding regions at its N-terminus (by MoRFchibi_web (residues 1-6), MoRFPred (residues 7-12), and DISOPRED3 (residues [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] ) and at C-terminus (by MoRFchibi_web (residues 261-268) and MoRFPred (residues 259-263)) ( Table 2) . Similarly, ORF3a of Human SARS and Bat CoV also shows MoRFs at N-and C-terminus with the help of MoRFchibi_web and MoRFPred ( Supplementary Tables 7 and 8) . These protein-binding regions in ORF3a may have role in its co-localization with E, M, and S viral proteins. Apart from MoRFs, it also displays several nucleotide-binding residues in all three viruses (see Supplementary Tables 9, 10, and 11). In fact, this represents maximum number of RNA and DNA binding residues as compared with all other accessory proteins. These results indicate that the IDPs/IDPRs of this protein could be utilized in molecular recognition (protein-protein, protein-RNA, and protein-DNA interaction).