Active site-based analysis of structural proteins for drug targets in different human Coronaviruses

Seven types of Coronaviruses (CoVs) have been identified that can cause infection in humans, including HCoV-229E, HCoV-NL63, HCoV-OC43, HCoV-HKU1, SARS-CoV, HCoV-MERS, and SARS-CoV-2. In this study, we investigated the genetic structure, the homology of the structural protein sequences, as well as the investigation of the active site of structural proteins. The active site of structural proteins was determined based on the previous studies, and the homology of their amino acid sequences and structure was compared. Multiple sequence alignment of Spike protein of HCoVs showed that the receptor-binding domain of SARS-CoV-2, SARS-CoV, and MERS-CoV was located at a similar site to the S1 subunit. The binding motif of PDZ (postsynaptic density-95/disks large/zona occludens-1) of the envelope protein, was conserved in SARS-CoV and SARS-CoV-2 according to multiple sequence alignment but showed different changes in the other HCoVs. Overall, spike protein showed the most variation in its active sites, but the other structural proteins were highly conserved. In this study, for the first time, the active site of all structural proteins of HCoVs as a drug target was investigated. The binding site of these proteins can be suitable targets for drugs or vaccines among HCoVs.