Structural and functional characterization of the Bacillus megaterium uvrBA locus and generation of UV-sensitive mutants.

The Bacillus megaterium genes uvrB and uvrA, encoding two subunits of the (A)BC excinuclease, which is responsible for nucleotide excision repair, were isolated and functionally characterized. RNA analyses revealed co-transcription of both genes probably forming a bicistronic operon. Expression of uvrB and uvrA was inducible by the DNA-damaging agent mitomycin C. This finding agrees with the presence of a potential DinR box within the uvrBA promoter. Single inactivation of uvrB or uvrA as well as the parallel knockout of both genes resulted in mutants highly sensitive to UV irradiation. Thus, this locus represents an attractive target for generating biologically safe containment strains of B. megaterium.