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The recombination deficient Enterococcus faecalis UV202 strain is a recA mutant
Keith E Weaver1, Shirisha G Reddy
1Division of Basic Biomedical Sciences, School of Medicine, University of South Dakota, Vermillion, SD 57069, USA. kweaver@usd.edu
Plasmid
|December 7, 2005
Summary
Researchers identified a specific mutation in the recA gene of Enterococcus faecalis. Restoring the wild-type recA gene successfully corrected UV sensitivity and recombination deficiency in this bacterial strain.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- The recA gene is crucial for DNA repair and recombination in bacteria.
- Enterococcus faecalis strain UV202 exhibits defects in UV resistance and genetic recombination.
- Understanding recA mutations is key to bacterial DNA repair mechanisms.
Purpose of the Study:
- To identify the genetic basis of the recA defect in Enterococcus faecalis UV202.
- To investigate the functional role of the identified recA mutation.
- To confirm the complementation of UV sensitivity and recombination deficiency by wild-type recA.
Main Methods:
- DNA sequencing of the recA gene in Enterococcus faecalis UV202.
- Site-directed mutagenesis or gene cloning to express wild-type recA.
- Complementation assays using a nisin-inducible expression vector.
Main Results:
- Sequencing revealed a glycine to aspartic acid substitution at amino acid 265 in the recA gene of UV202.
- Expression of the wild-type recA gene restored UV resistance to the UV202 strain.
- Complementation with wild-type recA also restored normal recombination proficiency to the UV202 strain.
Conclusions:
- The glycine to aspartic acid mutation at amino acid 265 in recA is responsible for the UV sensitive and recombination deficient phenotypes of Enterococcus faecalis UV202.
- Functional wild-type recA gene expression can effectively complement these defects.
- This study highlights the critical role of recA in DNA repair and recombination in Enterococcus faecalis.