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The AGG codon is translated slowly in E. coli even at very low expression levels
1Institute of Biological Chemistry, University of Copenhagen, Denmark.
Nucleic Acids Research
|April 11, 1988
Summary
Arginine AGG codons slow down translation more than CGU codons in Escherichia coli. This codon difference significantly reduces transcription past the pyrE attenuator, impacting gene expression.
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- Codon usage bias influences protein translation speed.
- The pyrE attenuator in Escherichia coli regulates transcription termination based on translation coupling.
Purpose of the Study:
- To investigate the translation speed of AGG codons compared to CGU codons for arginine.
- To determine the impact of AGG codon translation on transcription-translation coupling at the pyrE attenuator.
Main Methods:
- Insertion of tandem AGG or CGU codons into a leader peptide gene on a multicopy plasmid.
- Controlled transcription initiation using the lac-promoter and IPTG induction.
- Quantification of transcription frequency past the pyrE attenuator under different codon conditions.
Main Results:
- AGG codons were translated significantly slower than CGU codons, even at low expression levels.
- Presence of AGG codons reduced transcription past the pyrE attenuator approximately ninefold compared to CGU codons.
- AGG codons decoupled transcription from translation at the pyrE attenuator.
Conclusions:
- AGG codons are consistently translated slowly in Escherichia coli.
- Slow AGG codon translation disrupts transcription-translation coupling, affecting gene expression regulation.