Currently, no approved drug is available as a causative agent of coronavirus disease 2019 (COVID-19) except for some repurposed drugs. The first structure of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was reported in late 2019, based on that some vaccines and repurposed drugs were approved to prevent people from COVID-19 during the pandemic situation. Since then, new types of variants emerged and notably, the receptor binding domain (RBD) adopted different binding modes with angiotensin-converting enzyme 2 (ACE2); this made significant changes in the progression of COVID-19. Some of the new variants are highly infectious spreading fast and dangerous. The present study is focused on understanding the binding mode of the RBD of different mutated SARS-CoV-2 variants of concern (alpha to omicron) with the human ACE2 using molecular dynamics simulation. Notably, some variants adopted a new binding mode of RBD with ACE2 and formed different interactions, which is unlike the wild type; this was confirmed from the comparison of interaction between RBD-ACE2 of all variants with its wild-type structure. Binding energy values confirm that some mutated variants exhibit high binding affinity. These findings demonstrate that the variations in the sequence of SARS-CoV-2 S-protein altered the binding mode of RBD; this may be the reason that the virus has high transmissibility and causes new infections. This in-silico study on mutated variants of SARS-CoV-2 RBD with ACE2 insights into their binding mode, binding affinity, and stability. This information may help to understand the RBD-ACE2 binding domains, which allows for designing newer drugs and vaccines.
Keywords: MD simulation; RBD-ACE2; SARS-CoV-2; binding energy; mutation; variants.
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