of controlling competence gene expression and survival under stress conditions, is encoded by the fourth gene of a six-gene operon. The product of contains a potential helix-turn-helix motif, but shows no significant similarities with known protein sequences. The second and third genes encode proteins with similarities to zinc-finger proteins () and arginine kinases (), respectively. The product of contains a zinc-finger motif and an ATP-binding domain, and is highly similar to the product of the gene. A strain bearing a disruption of showed increased sensitivity to the alkylating agent methyl methanesulfonate. Furthermore, this mutant strain displayed decreased capacity for genetic recombination as measured by transformation experiments. The last open reading frame, encodes a protein with limited similarity in its C-terminal part to the gene product and to the UvrC DNA repair excinuclease. Inactivation of resulted in strongly diminished transformation with all types of DNA. Mutations affecting either or resulted in strains with decreased resistance to UV-irradiation in the stationary phase, indicating that these proteins play a role in the development of a nonspecific stationary-phase resistance to UV-irradiation. Moreover, these results suggest an involvement of both proteins in transformation and presumably in DNA repair.


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