Characterization and structural prediction of the putative ORF10 protein in SARS-CoV-2

Schuster, Noah A.

Upstream of the 3’-untranslated region in the SARS-CoV-2 genome is ORF10 which has been proposed to encode for the ORF10 protein. Current research is still unclear on whether this protein is synthesized, but further investigations are still warranted. Herein, this study uses multiple bioinformatic tools to biochemically and functionally characterize the ORF10 protein, along with predicting its tertiary structure. Results indicate a highly ordered, hydrophobic, and thermally stable protein that contains at least one transmembrane region. This protein also possesses high residue protein-binding propensity, primarily in the N-terminal half. An assessment of forty-one missense mutations reveal slight changes in residue flexibility, mainly in the C-terminal half. However, these same mutations do not inflict significant changes on protein stability and other biochemical features. The predicted model suggests the ORF10 protein contains a β-α-β motif with a β-molecular recognition feature occurring in the first β-strand. Functionally, the ORF10 protein could be a membrane protein. A single pocket was identified in this protein but found to possess low druggability. The ORF10 itself consists of two distinct lineages: the SARS-CoV lineage and the SARS-CoV-2 lineage. Evidence of strong positive selection (dN/dS = 4.01) and purifying selection (dN/dS = 0.713) were found within the SARS-CoV-2 lineage and SARS-CoV lineage, respectively. Collectively, these results continue to assess the biological relevance of ORF10 and its putatively encoded protein, thereby aiding in diagnostic and possibly vaccine development.