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The right end of MudI(Ap,lac)
1Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115.
Archives of Microbiology
|January 1, 1989
Summary
Stable bacteriophage MudI-(Ap,lac) derivatives generated sectoring operon fusions in S. typhimurium. Deletions at the MudI element
Area of Science:
- Molecular Biology
- Bacteriophage Genetics
- Microbial Genetics
Background:
- Bacteriophage Mu and its derivatives are powerful tools for genetic manipulation.
- MudI-(Ap,lac) is a stable derivative used for creating operon fusions.
- S. typhimurium is a model organism for bacterial genetics.
Purpose of the Study:
- To investigate the mechanism of sectoring phenotypes in MudI-(Ap,lac) operon fusions.
- To analyze the genetic basis of Lac- to Lac+ conversion in S. typhimurium.
- To elucidate the role of specific DNA structures in deletion formation.
Main Methods:
- Generation of MudI-(Ap,lac) operon fusions in S. typhimurium.
- Phenotypic analysis of lacZ expression and sectoring.
- DNA sequence analysis of MudI element ends and flanking regions.
Main Results:
- MudI-(Ap,lac) fusions exhibited sectoring, indicating instability.
- Lac- to Lac+ conversion resulted from small deletions at the MudI element's right end.
- Sequence analysis revealed an asymmetric inverted repeat of the attR site at this end.
Conclusions:
- The attR site's inverted repeat structure in MudI-(Ap,lac) likely mediates deletion formation.
- A model explaining the formation of this structure and subsequent deletions is proposed.
- This study clarifies the molecular basis of instability in MudI-generated fusions.