Open AccessHypomodification of the Wobble Base in tRNA Glu , tRNA Lys , and tRNA Gln Suppresses the Temperature-Sensitive Phenotype Caused by Mutant Release Factor 1
Author(s) -
Georgina Isak,
Monica Rydén-Aulin
Publication year - 2009
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.01485-08
Subject(s) - transfer rna , biology , mutant , escherichia coli , gene , wobble base pair , release factor , biochemistry , activator (genetics) , genetics , microbiology and biotechnology , rna
InEscherichia coli , release factor 1 (RF1) is one of two RFs that mediate termination; it specifically recognizes UAA and UAG stop codons. A mutant allele,prfA1 , coding for an RF1 that causes temperature-sensitive (Ts) growth at 42°C, was used to select for temperature-resistant (Ts+ ) suppressors. This study describes one such suppressor that is the result of an IS10 insertion into thecysB gene, giving a Cys− phenotype. CysB is a transcription factor regulating thecys regulon, mainly as an activator, which explains the Cys− phenotype. We have found that suppression is a consequence of the lost ability to donate sulfur to enzymes involved in the synthesis of thiolated nucleosides. From genetic analyses we conclude that it is the lack of the 5-methylaminomethyl-2-thiouridine (mnm5 s2 U) modification of the wobble base of tRNAGlu , tRNALys , and/or tRNAGln that causes the suppressor phenotype.