Translational control of transcription termination at the attenuator of the Escherichia coli tryptophan operon.
Open Access
- 1 December 1978
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 75 (12), 5988-5992
- https://doi.org/10.1073/pnas.75.12.5988
Abstract
Two regulatory mutants altered in the leader region of the E. coli tryptophan (trp) operon were isolated. In 1 mutant, trpL29, the AUG translation start codon for the trp leader peptide is replaced by AUA. The other mutant, trpL75, has a G.fwdarw. A change at residue 75, immediately after the UGA translation stop codon for the trp leader peptide. In vivo, trpL29 and trpL75 increase the efficiency of transcription termination at the trp attenuator 3- to 5-fold. trpL29 and trpL75 also fail to respond fully to tryptophan starvation and other conditions that normally relieve transcription termination at the trp attenuator. The trpL29 mutation, which presumably reduces synthesis of the trp leader peptide, is cis dominant. The effect of starvation for a number of the amino acids in the trp leader peptide was determined. Only starvation for tryptophan and arginine, amino acids that occur at residues 10, 11 and 12 of the 14-residue trp leader peptide, elicits relief of transcription termination. Translation of trp leader RNA is probably involved in regulation of transcription termination at the attenuator. A model is discussed in which the location of the ribosome synthesizing the leader peptide is communicated to the RNA polymerase transcribing the leader region.Keywords
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