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Isolation of Translating Ribosomes Containing Peptidyl-tRNAs for Functional and Structural Analyses
Published on: February 25, 2011
The different roles of tryptophan transfer RNA in regulating trp operon expression in E. coli versus B. subtilis
1Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA. yanofsky@cmgm.stanford.edu
Abstract:
Escherichia coli and Bacillus subtilis use different mechanisms of sensing and responding to tryptophan and uncharged tRNA(Trp) as regulatory signals. In E. coli, tryptophan activates a repressor that binds to the trp promoter- operator, inhibiting transcription initiation. In B. subtilis, tryptophan activates an RNA-binding protein, TRAP, which binds to the trp operon leader RNA, causing transcription termination. In E. coli uncharged tRNA(Trp) accumulation stalls the ribosome attempting translation of tandem Trp codons in the leader-peptide coding region of the operon. This stalling permits the formation of an RNA antiterminator structure, preventing transcription termination. In B. subtilis uncharged tRNA(Trp) accumulation activates transcription and translation of the at operon. AT protein inhibits tryptophan-activated TRAP, thereby preventing TRAP-mediated transcription termination. These differences might reflect the unique organizational features of the respective trp operons and their ancestry.
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Repressible Operon: trp Operon

