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PMID: 3922957 Published · ppublish English Journal Article Research Support, U.S. Gov't, P.H.S.

Mutations that convert the four leucine codons of the Salmonella typhimurium leu leader to four threonine codons.

Journal of bacteriology ·Vol. 162 ·No. 3 ·1985-06-00 ·Pages 943-9

Carter PW, Weiss DL, Weith HL, Calvo JM

Abstract

In Salmonella typhimurium, expression of the leucine operon is regulated by a transcription attenuation mechanism. According to a current model of attenuation, elevated expression of this operon requires that a ribosome stall at one of four adjacent codons for leucine on a leader RNA. We used oligonucleotide-directed mutagenesis to convert the four leucine codons of the S. typhimurium leu leader to four threonine codons. Analysis of the resulting mutant operon showed that almost all regulation by leucine had been abolished. The mutant operon was, instead, partially derepressed by a limitation for charged threonine tRNA. These results provide direct evidence for the function for the four leucine codons postulated by the attenuator model. An unexpected observation made during these studies was that the wild-type leu operon was partially derepressed by starvation for threonine.

MeSH Terms
Codon Leucine/genetics Mutation Operon RNA, Messenger RNA, Transfer, Amino Acyl/metabolism Salmonella typhimurium/genetics Threonine/genetics
Chemicals
Codon RNA, Messenger RNA, Transfer, Amino Acyl Threonine Leucine
Authors & Affiliations
4 authors, click to expand affiliations / ORCID
Carter P W
Weiss D L
Weith H L
Calvo J M
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31 references, click to expand
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Article Info
Journal
Journal of bacteriology
Abbr.
J Bacteriol
ISSN
0021-9193
DOI
10.1128/jb.162.3.943-949.1985
Published
1985-06-00
Pages
943-9
Language
English
Region
United States
NLM ID
2985120R
PMCID
PMC215867
Subset
IM
Grants
PHS HHS · 14340 · United States
NIGMS NIH HHS · 5 T32 GM07273-08 · United States
External Links
PubMed source DOI: 10.1128/jb.162.3.943-949.1985 PMC Full Text View journal details
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