Investigation of the Mutations in the SARS-CoV-2 Envelope Protein and Its Interaction with the PALS1 by Molecular Docking.

Background: The envelope (E) protein of globally circulating severe acute respiratory syndrome coronavirus 2 (SARS CoV 2) is highly conserved. This study aimed to find the mutation rate of the E genes in COVID-19 patients, and also to evaluate the conformational characteristics of viral E protein.

Methods: In this study, 120 patients with SARS-CoV-2 positive test results were selected according to real-time PCR assay. Specific primers for conventional PCR have been used to amplify E gene; furthermore, to identify the E gene mutations, direct sequencing of the E genes was also done. Bioinformatics techniques were used to investigate the possible effects of antigenic changes and 3D characteristics of amino acid substitutions. Also, the immunogenicity of wild-type and mutant E was analyzed utilizing a ClusPro docking server and the IEDB online platform.

Results: A total of 120 COVID-19 patients were included (57.5% were male and 42.5% female), with an overall mean age of 55.70±10.61 years old. Of 10 nucleotide changes, 8 (80%) were silent. Also, 2 (20%) missense mutations (amino acid altering) were found in the E gene (L73F and S68F).

Conclusions: These mutations insert some new helix structures in the E mutants. Also, the results of molecular docking studies indicated that both S68F and L73F mutations could notably enhance the stability and binding affinity of protein E's C-terminal motif to the Protein Associated with LIN7 1, MAGUK P55 Family Member (PALS1) which may probably increase local viral spread, and infiltration of immune cells into lung alveolar spaces.