Met58 and di-acidic motif located at C-terminal region of SARS-CoV-2 ORF6 plays a crucial role in its structural conformations

Abstract

Despite being mostly neglected in structural biology, the C-terminal Regions (CTRs) are studied to be multifunctional in humans as well as in viruses. Their role in cellular processes such as trafficking, protein-protein interactions, and protein-lipid interactions are known due to their structural properties. In our previous findings on SARS-CoV-2 Spike and NSP1 proteins, the C-terminal regions (CTRs) are observed to be disordered and experimental evidence showed a gain of structure properties in different physiological environments. In this line, we have investigated the structural dynamics of CTR (residues 38-61) of SARS-CoV-2 ORF6 protein, disrupting bidirectional transport between the nucleus and cytoplasm. Like Spike and NSP1-CTR, the ORF6-CTR is also disordered in nature but possesses gain of structure properties in minimal physiological conditions. As per studies, the residue such as Methionine at 58th position in ORF6 is critical for interaction with Rae1-Nup98. Therefore, along with M58, we have identified a few other mutations from the literature and performed extensive structure modelling and dynamics studies using computational simulations. The exciting revelations in CTR models provide evidence of its structural flexibility and possible capabilities to perform multifunctionality inside the host.