RRC ID 35482
Author Benítez-Páez A, Villarroya M, Armengod ME.
Title The Escherichia coli RlmN methyltransferase is a dual-specificity enzyme that modifies both rRNA and tRNA and controls translational accuracy.
Journal RNA
Abstract Modifying RNA enzymes are highly specific for substrate-rRNA or tRNA-and the target position. In Escherichia coli, there are very few multisite acting enzymes, and only one rRNA/tRNA dual-specificity enzyme, pseudouridine synthase RluA, has been identified to date. Among the tRNA-modifying enzymes, the methyltransferase responsible for the m(2)A synthesis at purine 37 in a tRNA set still remains unknown. m(2)A is also present at position 2503 in the peptidyl transferase center of 23S RNA, where it is introduced by RlmN, a radical S-adenosyl-L-methionine (SAM) enzyme. Here, we show that E. coli RlmN is a dual-specificity enzyme that catalyzes methylation of both rRNA and tRNA. The ΔrlmN mutant lacks m(2)A in both RNA types, whereas the expression of recombinant RlmN from a plasmid introduced into this mutant restores tRNA modification. Moreover, RlmN performs m(2)A(37) synthesis in vitro using a tRNA chimera as a substrate. This chimera has also proved useful to characterize some tRNA identity determinants for RlmN and other tRNA modification enzymes. Our data suggest that RlmN works in a late step during tRNA maturation by recognizing a precise 3D structure of tRNA. RlmN inactivation increases the misreading of a UAG stop codon. Since loss of m(2)A(37) from tRNA is expected to produce a hyperaccurate phenotype, we believe that the error-prone phenotype exhibited by the ΔrlmN mutant is due to loss of m(2)A from 23S rRNA and, accordingly, that the m(2)A2503 modification plays a crucial role in the proofreading step occurring at the peptidyl transferase center.
Volume 18(10)
Pages 1783-95
Published 2012-10-1
DOI 10.1261/rna.033266.112
PII rna.033266.112
PMID 22891362
PMC PMC3446703
MeSH Base Sequence Catalysis Cloning, Molecular Escherichia coli Proteins / metabolism Escherichia coli Proteins / physiology* Methyltransferases / metabolism Methyltransferases / physiology* Models, Biological Models, Molecular Molecular Sequence Data Nucleic Acid Conformation Protein Biosynthesis* / physiology RNA, Ribosomal / chemistry RNA, Ribosomal / genetics RNA, Ribosomal / metabolism* RNA, Transfer / chemistry RNA, Transfer / genetics RNA, Transfer / metabolism* Reproducibility of Results Substrate Specificity
IF 4.32
Times Cited 48
Prokaryotes E. coli ME9062(BW25113)?