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Updated: Aug 3, 2026
11:19
Inducing a Site Specific Replication Blockage in E. coli Using a Fluorescent Repressor Operator System
Published on: August 21, 2016
Intracellular Trp repressor levels in Escherichia coli
Journal of Bacteriology
|July 1, 1986
Summary
This study developed a radioimmunoassay to measure Trp repressor protein in E. coli. Tryptophan levels directly influence Trp repressor concentration, confirming autoregulation of the trpR gene.
Area of Science:
- Molecular Biology
- Microbiology
- Biochemistry
Background:
- The Trp repressor protein regulates the tryptophan operon in Escherichia coli.
- Understanding Trp repressor levels is crucial for comprehending gene expression control.
Purpose of the Study:
- To develop a direct method for quantifying intracellular Trp repressor protein in E. coli.
- To investigate the relationship between extracellular L-tryptophan levels and intracellular Trp repressor concentration.
Main Methods:
- Development of a radioimmunoassay using antisera against purified Trp repressor protein.
- Direct measurement of intracellular Trp repressor content in various E. coli strains (K-12 and B/r).
Main Results:
- Intracellular Trp repressor levels varied 2.5- to 3-fold in response to L-tryptophan concentration (15-44 ng/mg protein).
- Cell growth rate and culture age did not significantly affect repressor concentrations.
- Addition of L-tryptophan led to decreased intracellular Trp repressor levels, ranging from 120 to 375 dimers per cell.
Conclusions:
- This study provides the first direct measurements of Trp repressor levels in E. coli.
- Findings confirm the autoregulatory mechanism of the trpR gene in response to tryptophan availability.
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