Structural resilience of conserved-site mutations in the MERS-CoV membrane protein: insights into stability and conformational dynamics

MERS-CoV remains a significant global health challenge due to sporadic outbreaks. The ongoing emergence of new viral variants, particularly among betacoronaviruses, underscores the importance of understanding mutations in structural proteins. The membrane (M) protein, a highly conserved structural component essential for viral assembly, is a promising target for therapeutic intervention, and any mutations in this protein are particularly concerning as they may compromise antiviral efficacy. Despite its critical role, the structural consequences of M protein mutations remain poorly characterised. This study investigates six conserved amino-acid substitutions (F27L, A62T, V69L, I82T, T127I, and R162H) identified in the M- protein across bat coronaviruses, SARS-related coronaviruses, and MERS-CoV. Using atomistic molecular dynamics simulations, we examined how these substitutions affect MERS-CoV M protein stability, dimerisation, and interaction with the N protein. All mutants largely preserved native-like structural stability relative to the wild type, indicating that the M protein is resilient to mutation-induced alterations at conserved sites. Although the R162H substitution within the β-sheet domain induced localised flexibility, it did not result in substantial global conformational changes. Notably, the I82T mutant identified exhibited structural stability similar to the wild-type protein, supporting its evolutionary persistence. Furthermore, the mutant M proteins maintained favourable dimeric interactions and stable binding with the N protein. Collectively, these findings elucidate how conserved-site mutations modulate M-protein dynamics while preserving structural and functional integrity, potentially contributing to coronavirus adaptability.