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Effect of Escherichia coli nusG function on lambda N-mediated transcription antitermination
S L Sullivan1, D F Ward, M E Gottesman
1Institute of Cancer Research, Columbia University College of Physicians and Surgeons, New York, New York 10032.
Journal of Bacteriology
|February 1, 1992
Summary
Escherichia coli NusG is a key factor in suppressing transcription termination. This study identifies NusG as a component of the N antitermination complex and suggests its role in Rho-dependent termination.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Escherichia coli Nus factors and bacteriophage lambda N protein cooperate to prevent transcription termination.
- NusA protein interacts with N protein and RNA polymerase, potentially linking other Nus factors.
Purpose of the Study:
- To identify novel components of the lambda N antitermination system.
- To investigate the role of the NusG protein in transcription regulation.
Main Methods:
- Isolation and characterization of host revertants restoring N activity in nusA1 mutants.
- Genetic mapping of mutations to specific chromosomal regions.
- Complementation studies using multicopy plasmids.
Main Results:
- A point mutation in the nusG gene (nusG4) restored N activity in nusA1 mutants.
- The nusG4 mutation suppressed specific Nus factor mutations (nusE71) but not others.
- Expression of wild-type NusG suppressed rho mutants, indicating a role in Rho-dependent termination.
Conclusions:
- NusG is implicated as a component of the lambda N antitermination complex.
- NusG plays a role in both N-mediated antitermination and Rho-dependent transcription termination.