Dataset Information

Mechanochemical Function of Myosin II: Investigation into the Recovery Stroke and ATP Hydrolysis.

ABSTRACT: Myosin regulates muscle function through a complex cycle of conformational rearrangements coupled with the hydrolysis of adenosine triphosphate (ATP). The recovery stroke reorganizes the myosin active site to hydrolyze ATP and cross bridge with the thin filament to produce muscle contraction. Engineered mutations K84M and R704E in Dictyostelium myosin have been designed to specifically inhibit the recovery stroke and have been shown to indirectly affect the ATPase activity of myosin. We investigated these mutagenic perturbations to the recovery stroke and generated thermodynamically correct and unbiased trajectories for native ATP hydrolysis with computationally enhanced sampling methods. Our methodology was able to resolve experimentally observed changes to kinetic and equilibrium dynamics for the recovery stroke with the correct prediction in the severity of these changes. For ATP hydrolysis, the sequential nature along with the stabilization of a metaphosphate intermediate was observed in agreement with previous studies. However, we observed glutamate 459 being utilized as a proton abstractor to prime the attacking water instead of a lytic water, a phenomenon not well categorized in myosin but has in other ATPases. Both rare event methodologies can be extended to human myosin to investigate isoformic differences from Dictyostelium and scan cardiomyopathic mutations to see differential perturbations to kinetics of other conformational changes in myosin such as the power stroke.

SUBMITTER: Baldo AP

PROVIDER: S-EPMC7696650 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Conventional myosin is representative of biomolecular motors in which the hydrolysis of adenosine triphosphate (ATP) is coupled to large-scale structural transitions both in and remote from the active site. The mechanism that underlies such "mechanochemical coupling," especially the causal relationship between hydrolysis and allosteric structural changes, has remained elusive despite extensive experimental and computational analyses. In this study, using combined quantum mechanical and molecular mechanical simulations and different conformations of the myosin motor domain, we provide evidence to support that regulation of ATP hydrolysis activity is not limited to residues in the immediate environment of the phosphate. Specifically, we illustrate that efficient hydrolysis of ATP depends not only on the proper orientation of the lytic water but also on the structural stability of several nearby residues, especially the Arg238-Glu459 salt bridge (the numbering of residues follows myosin II in Dictyostelium discoideum) and the water molecule that spans this salt bridge and the lytic water. More importantly, by comparing the hydrolysis activities in two motor conformations with very similar active-site (i.e., Switches I and II) configurations, which distinguished this work from our previous study, the results clearly indicate that the ability of these residues to perform crucial electrostatic stabilization relies on the configuration of residues in the nearby N-terminus of the relay helix and the "wedge loop." Without the structural support from those motifs, residues in a closed active site in the post-rigor motor domain undergo subtle structural variations that lead to consistently higher calculated ATP hydrolysis barriers than in the pre-powerstroke state. In other words, starting from the post-rigor state, turning on the ATPase activity requires not only displacement of Switch II to close the active site but also structural transitions in the N-terminus of the relay helix and the "wedge loop," which have been proposed previously to be ultimately coupled to the rotation of the converter subdomain 40 A away.

Dataset Information

Mechanochemical Function of Myosin II: Investigation into the Recovery Stroke and ATP Hydrolysis.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets