Identification of the rate-determining step of tRNA-guanine transglycosylase from Escherichia coli.

ABSTRACT: The modified RNA base queuine [7-(4,5-cis-dihydroxy-1-cyclopenten-3-ylaminomethyl)-7-deazaguanine] is present in tRNA because of a unique base-exchange process catalyzed by tRNA-guanine transglycosylase (TGT). Previous studies have suggested the intermediacy of a covalent TGT-RNA complex. To exist on the reaction pathway, this covalent complex must be both chemically and kinetically competent. Chemical competence has been demonstrated by the crystal structure studies of Xie et al. [(2003) Nat. Struct. Biol. 10, 781-788]; however, evidence of kinetic competence had not yet been established. The studies reported here unequivocally demonstrate that the TGT-RNA covalent complex is kinetically capable of occurring on the TGT reaction pathway. These studies further suggest that dissociation of p

SUBMITTER: Garcia GA 

PROVIDER: S-EPMC2789984 | biostudies-literature | 2009 Dec

REPOSITORIES: biostudies-literature