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Initial trp operon sequence in Escherichia coli is transcribed without coupling to translation
Molecular & General Genetics : MGG
|July 23, 1976
Summary
Ribosome binding in the trp operon leader mRNA is crucial for continued transcription. Initial transcription occurs independently, but later stages require functional translation machinery.
Area of Science:
- Molecular Biology
- Microbial Genetics
- Gene Regulation
Background:
- The trp operon in Escherichia coli is a well-studied model for gene regulation.
- Understanding the interplay between transcription and translation is key to gene expression control.
Purpose of the Study:
- To investigate the role of ribosome binding in the transcription of the trp operon leader region.
- To elucidate the relationship between translation and transcription continuation in this operon.
Main Methods:
- Analysis of trp operon transcription in various deletion mutants and a temperature-sensitive strain.
- Detection of leader region mRNA using specific molecular probes.
- Sedimentation analysis of polyribosomes to assess mRNA-ribosome association.
Main Results:
- Transcription of the trp operon leader region was studied in deletion mutants and a strain with a temperature-sensitive ribosomal protein factor.
- Ribosome binding sites were identified in the middle of the leader mRNA sequence.
- Initial transcription was independent of translation, but continuation required ribosome function.
Conclusions:
- Ribosomes bind to specific sites within the trp operon leader mRNA in vivo.
- The initiation of trp operon transcription does not necessitate a functional translational apparatus.
- Sustained RNA synthesis beyond the initial ribosome binding site is dependent on ribosome activity.