Stepwise analyses of metal ions in RNase H catalysis from substrate destabilization to product release.

ABSTRACT: In two-metal catalysis, metal ion A has been proposed to activate the nucleophile and metal ion B to stabilize the transition state. We recently reported crystal structures of RNase H-RNA/DNA substrate complexes obtained at 1.5-2.2 Angstroms. We have now determined and report here structures of reaction intermediate and product complexes of RNase H at 1.65-1.85 Angstroms. The movement of the two metal ions suggests how they may facilitate RNA hydrolysis during the catalytic process. Firstly, metal ion A may assist nucleophilic attack by moving towards metal ion B and bringing the nucleophile close to the scissile phosphate. Secondly, metal ion B transforms from an irregular coordination in the substrate complex to a more regular geometry in the product complex. The exquisite sensitivity of

SUBMITTER: Nowotny M 

PROVIDER: S-EPMC1456928 | biostudies-literature | 2006 May

REPOSITORIES: biostudies-literature