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Protective role for H-NS protein in IS1 transposition
Claudine Rouquette1, Marie-Claude Serre, David Lane
1Laboratoire de Microbiologie et Génétique Moléculaire, CNRS, Toulouse, France.
Journal of Bacteriology
|March 19, 2004
Summary
Host factor H-NS is crucial for IS1 transposition and transposase InsAB' protein stability. Mutations in hns abolish the SOS response and reduce transposition, impacting InsAB' protein levels and suggesting a role in translation or protein degradation.
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- The insertion element IS1 utilizes transposase InsAB' to mediate DNA transposition.
- IS1 transposition can induce the bacterial SOS response, a DNA damage repair pathway.
- Host factors play a significant role in regulating transposition mechanisms.
Purpose of the Study:
- To identify host factors involved in IS1 transposition using the SOS response as a screening tool.
- To elucidate the function of the H-NS protein in IS1 transposition and InsAB' protein stability.
Main Methods:
- Utilized the SOS response to screen for host mutations affecting InsAB' function.
- Analyzed transposition frequencies in wild-type and mutant strains.
- Examined InsAB' protein levels and mRNA stability using protein profiling and radiolabeling.
Main Results:
- Mutations in the hns gene abolished the InsAB'-induced SOS response and reduced IS1 transposition over 100-fold.
- In hns-null mutants, InsAB' protein was undetectable, despite unaltered transcription and mRNA levels.
- Mutations in lon and ssrA partially restored InsAB' synthesis in hns strains.
Conclusions:
- The H-NS protein is essential for IS1 transposition, likely by stabilizing the InsAB' protein.
- The absence of H-NS leads to issues in InsAB' translation completion or increased degradation of the nascent protein.
- Host factors like H-NS are critical regulators of mobile genetic element activity.