Effects of the binding of calcium ions on the structure and dynamics of the ΦX174 virus investigated using molecular dynamics

It is known that the presence of calcium ions (Ca^2?+?) is necessary for the enterobacterial virus ΦX174 to inject its DNA into the host cell, and that some mutations in the major capsid proteins lead to better survivability at higher temperatures. Our goal in the current study is to determine the physical changes in both the wild-type and mutant virus due to the binding of Ca^2?+?. Thus, we performed molecular dynamics simulations of the ΦX174 major capsid protein complex with and without Ca^2?+? bound. Our results show that binding of Ca^2?+? leads to energetic and dynamical changes in the virus proteins. In particular, the results suggest that binding of Ca^2?+? is energetically favorable and that the mutation leads to increased fluctuations of the protein complex (especially with the calcium ions bound to the complex), which may increase the rate of genome packaging and ejection for ΦX174.