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RNA polymerase mutant with altered sigma factor in Escherichia coli
Molecular & General Genetics : MGG
|September 20, 1978
Summary
Researchers precisely mapped the sigma factor (rpoD) gene in E. coli using F
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- The sigma factor (rpoD) is crucial for DNA-dependent RNA polymerase function.
- Precise genetic mapping of essential genes aids in understanding cellular processes.
Purpose of the Study:
- To precisely map the location of the E. coli rpoD gene.
- To identify and characterize mutations affecting sigma factor structure and RNA polymerase activity.
Main Methods:
- Precise gene mapping using F' factors.
- Localized mutagenesis to generate temperature-sensitive mutants near the uxaA gene.
- Analysis of RNA polymerase properties (thermostability, salt optimum) in mutant strains.
Main Results:
- The rpoD gene was mapped to the dnaG-uxaAC region.
- A temperature-sensitive mutation (U303) was identified, altering sigma factor structure.
- This mutation resulted in RNA polymerase with altered thermostability and salt concentration optimum.
- The U303 mutation maps near the dnaG locus at 66 min and affects cell growth.
Conclusions:
- The rpoD gene's location was precisely determined in the E. coli genetic map.
- Structural alterations in the sigma factor can directly impact RNA polymerase function and cellular growth.