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The role of the RecC subunit of the RecBCD enzyme in recombination and DNA repair

The crystal structure of the RecBCD enzyme has been recently solved, which enables more precise research of the least known RecC subunit. It is already known that the N-terminal domain of the RecC subunit is required for Chi activity while the C-terminal domain is important for RecD assembly in RecBCD. To gain further insight into the importance of the RecC subunit several recC mutants have been constructed and characterized. Typical nonsense or missense mutants in the C-terminal domain of the recC gene are recombination proficient but nuclease deficient, a phenotype which mimics that of recD deletion mutations. In this study, we focused on the previously characterized recC73 mutant that has a nonfunctional C-terminal domain (deletion of T on 1938 position). In addition, we also made five new point-missense recC mutants using PCR site directed mutagenesis. According to the literature, the recC73 mutant is considered a null mutant. In contrast, we showed that the recC73 mutant is recombination proficient but only when some of the gene products from the RecF pathway are present (RecFOR and RecJ). The characterization of five additional missense recC mutants is underway.

RecC subunit; RecBCD enzyme; recombination; DNA repair

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