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The copyright holder for this preprint (which was not peer-reviewed) is the .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 ORF8 protein found in early SARS-CoV-2 isolates having 121 residues and according to our analysis, it shares a 90.05% sequence identity with ORF8 protein of Bat CoV ( Figure 12C) . Furthermore, Figures 12A and 12B show that there is no intrinsic disorder in both ORF8 proteins from SARS-CoV-2 and Bat CoV. Therefore, these two proteins predicted to be completely structured having a mean PPID of 0.00%. In ORF8a and ORF8b proteins of the Human SARS, the predicted disorder is estimated to be 2.56% and 2.38%, respectively (Table 1) . Graphs in Figures 13A and 13B illustrate the presence of some disorder near the N-and C-terminals of ORF8a and ORF8b proteins. Table 2 shows the identified MoRF regions in ORF8 of SARS-CoV-2. It shows three MoRF regions (residues 1-5, 26-52, and 69-91) by MoRFchibi_web and one MoRF region (residues 1-10) by DISOPRED3. In Human SARS, the N-terminus of both ORF8a (residues 1-39) and ORF8b (residues 1-83) was found to be MoRF by MoRFchibi_web server (Supplementary Table 7) . Further, four proteinbinding regions (residues 26-53, 70-91, 98-104, and 113-130) were identified by MoRFchibi_web server in Bat CoV (Supplementary Table 8 ). Apart from protein-binding, ORF8 of SARS-CoV-2, ORF8a and ORF8b of Human SARS, and ORF8 of Bat CoV also comprise several nucleotide-binding residues (see Supplementary Table 9 , 10, and 11).