Drugs swapping in coronavirus strains: a structural biology view.

Coronavirus belongs to the coronaviridae family, having a single-stranded RNA as genetic material of 26-42 kb in size. The first coronavirus infection emerged in 2002, caused by SARS-CoV1. Since then, genome sequences and three-dimensional structures of crucial proteins and enzymes of the virus have been studied in detail. The novel coronavirus (nCoV) outbreak has caused the COVID19 pandemic, which is responsible for the deaths of millions of people worldwide. The nCoV was later renamed as SARS-CoV2. The details of most of the COV proteins are available at the atomic and molecular levels. The entire genome is made up of 12 open reading frames that code for 27 different proteins. The spike surface glycoprotein, the envelope protein, the nucleocapsid protein, and the membrane protein are the four structural proteins which are required for virus attachment, entrance, assembly, and pathogenicity. The remaining proteins encoded are called non-structural (NSPs) and support the survival of the virus. Several non-structural proteins are also validated targets for drug development against coronavirus and are being used for drug design purposes. To perform a comparative study, sequences and three-dimensional structures of four crucial viral enzymes, Mpro, PLpro, RdRp, and EndoU from SARS-CoV1 and SARS-CoV2 variants were analyzed. The key structural elements and ligands recognizing amino acid residues were found to be similar in enzymes from both strains. The significant sequences and structural resemblance also suggest that a drug developed either for SARS-CoV1 or SARS-CoV2 using these enzymes may also have the potential to cross-react.Communicated by Ramaswamy H. Sarma.