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Published on: August 12, 2010
Regulation of gene expression by site-specific inversion
Cell
|September 1, 1978
Summary
A site-specific inversion event drives phase variation in Salmonella by altering the H2 flagellin gene. This process is independent of the E. coli RecA pathway, with key gene regions mapped via deletion analysis.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Salmonella exhibits phase variation, a mechanism for altering surface antigens like flagellin.
- The H2 flagellin gene's regulation is crucial for Salmonella's immune evasion strategies.
Purpose of the Study:
- To elucidate the molecular mechanism behind Salmonella phase variation.
- To identify and map the genetic elements responsible for H2 flagellin gene switching.
Main Methods:
- Heteroduplex analysis of recombinant DNA molecules.
- Site-specific inversion mapping using deletion derivatives.
- Restriction site mapping within the inversion region.
Main Results:
- A site-specific inversion event of approximately 800 base pairs controls H2 flagellin expression.
- The H2 gene was localized to within 300 base pairs of the inversion region.
- The inversion mechanism is independent of the E. coli RecA recombination pathway.
Conclusions:
- Site-specific DNA inversion is the primary mechanism for H2 flagellin phase variation in Salmonella.
- The identified inversion region and mapped H2 gene provide a detailed understanding of this genetic switch.
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