A conformational transition state accompanies tryptophan activation by B. stearothermophilus tryptophanyl-tRNA synthetase.

ABSTRACT: B. stearothermophilus tryptophanyl-tRNA synthetase catalysis proceeds via high-energy protein conformations. Unliganded MD trajectories of the pretransition-state complex with Mg(2+)ATP and the (post) transition-state analog complex with adenosine tetraphosphate relax rapidly in opposite directions, the former regressing, the latter progressing along the structural reaction coordinate. The two crystal structures (rmsd 0.7 A) therefore lie on opposite sides of a conformational free-energy maximum as the chemical transition state forms. SNAPP analysis illustrates the complexity of the associated long-range conformational coupling. Switching interactions in four nonpolar core regions are locally isoenergetic throughout the transition. Different configurations, however, propagate their effects

SUBMITTER: Kapustina M 

PROVIDER: S-EPMC2693061 | biostudies-literature | 2007 Oct

REPOSITORIES: biostudies-literature