Bacterial toxin RelE: a highly efficient ribonuclease with exquisite substrate specificity using atypical catalytic residues.

ABSTRACT: The toxin RelE is a ribosome-dependent endoribonuclease implicated in diverse cellular processes, including persistence. During amino acid starvation, RelE inhibits translation by cleaving ribosomal A-site mRNA. Although RelE is structurally similar to other microbial endoribonucleases, the active-site amino acid composition differs substantially and lacks obvious candidates for general acid-base functionality. Highly conserved RelE residues (Lys52, Lys54, Arg61, Arg81, and Tyr87) surround the mRNA scissile phosphate, and specific 16S rRNA contacts further contribute to substrate positioning. We used a single-turnover kinetic assay to evaluate the catalytic importance of individual residues in the RelE active site. Within the context of the ribosome, RelE rapidly cleaves A-site mRNA at a r

SUBMITTER: Griffin MA 

PROVIDER: S-EPMC3910103 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature