Intrinsic GTPase activity of a ribosomal maturation protein CgtA is associated with its inter-domain movement: insights from MD simulations and biochemical studies.

CgtA is an essential ribosome associated GTPase protein of bacteria. It has three domains, viz., Obg, GTPase, and C-terminal domain. It is a multifunctional protein and it is being considered as a potential drug target against bacterial infections. Despite the importance, CgtA's action mechanisms are not well known which warrants further study. Towards that goal, we are pursuing biochemical and computational studies in Vibrio cholerae CgtA (CgtA). Biochemically we found that a single amino acid substitution from Gly98 to Asp98 belonging to the Obg domain caused reduced GTPase activity of CgtA. The results from our comparative MD simulations studies revealed that in silico amino acid substitution for Gly98Asp influenced the inter-domain movement between Obg domain and GTPase domain. Moreover, we found significant alteration of intra-domain movements among the P-loop, G4 box, and G5 box of the GTPase domain, implying a potential cause for the reduced GTPase activity.