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Increased bar minigene mRNA stability during cell growth inhibition
Author(s) -
Valadez J. Gerardo,
HernándezSánchez Javier,
Magos Marco A.,
Ontiveros Carlos,
Guarneros Gabriel
Publication year - 2001
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2001.02214.x
Subject(s) - minigene , biology , messenger rna , microbiology and biotechnology , bar (unit) , genetics , alternative splicing , gene , physics , meteorology
Bacteriophage lambda is unable to grow vegetatively on Escherichia coli mutants defective in peptidyl‐tRNA hydrolase (Pth) activity. Mutations which allow phage growth on the defective host have been located at regions named bar in the lambda genome. Expression of wild‐type bar regions from plasmid constructs results in inhibition of protein synthesis and lethality to Pth‐defective cells. Two of these wild‐type bar regions, bar I + and bar II + , contain minigenes with similar AUG–AUA–stop codon sequences preceded by different Shine–Dalgarno (SD) and spacer regions. The induced expression of bar I + and bar II + regions from plasmid constructs resulted in similar patterns of protein synthesis inhibition and cell growth arrest. Therefore, these deleterious effects may stem from translation of the transcripts containing the minigene two‐codon ‘ORF’ (open reading frame). To test for this possibility, we assayed the effect of point mutations within the bar I minigene. The results showed that a base pair substitution within the SD and the two‐codon ‘ORF’ sequences affected protein synthesis and cell growth inhibition. In addition, mRNA stability was altered in each mutant. Higher mRNA stability correlated with the more toxic minigenes. We argue that this effect may be caused by ribosome protection of the mRNA in paused complexes as a result of deficiency of specific tRNA.