Mechanism of N-methylation by the tRNA m1G37 methyltransferase Trm5.

ABSTRACT: Trm5 is a eukaryal and archaeal tRNA methyltransferase that catalyzes methyl transfer from S-adenosylmethionine (AdoMet) to the N(1) position of G37 directly 3' to the anticodon. While the biological role of m(1)G37 in enhancing translational fidelity is well established, the catalytic mechanism of Trm5 has remained obscure. To address the mechanism of Trm5 and more broadly the mechanism of N-methylation to nucleobases, we examined the pH-activity profile of an archaeal Trm5 enzyme, and performed structure-guided mutational analysis. The data reveal a marked dependence of enzyme-catalyzed methyl transfer on hydrogen ion equilibria: the single-turnover rate constant for methylation increases by one order of magnitude from pH 6.0 to reach a plateau at pH 7.0. This suggests a mechanism involv

SUBMITTER: Christian T 

PROVIDER: S-EPMC2995409 | biostudies-literature | 2010 Dec

REPOSITORIES: biostudies-literature