Determination of the Paracoccus denitrificans SOS box

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Abstract
By gel retardation experiments with crude cell extracts of paracoccus denitrificans it was demonstrated that a protein specifically binds to the promoter of the P. denitrificans recA gene. PCR mutagenesis of the recA By gel retardation experiments with crude cell extracts of Paracoccus promoter showed that the GAACN(7)GAAC motif is required for the formation of the DNA-protein complex. This protein also binds to the GTTCN(7)GTTC motif. which is present in the promoter of the P. denitrificans uvrA gene. Mutational analysis of the promoter regions of both P. denitrificans recA and uvrA genes indicated that the GAACN(7)GAAC and GTTCN(7)GTTC sequences are required for DNA-damage-mediated induction of these two genes in vivo. Furthermore, the P. denitrificans recA gene was DNA-damage-inducible when introduced into cells of the phylogenetically related phototrophic bacterium Rhodobacter sphaeroides, although this inducibility was lost in mutants in the GAACN(7)GAAC motif. These results indicate that P. denitrificans possesses the same SOS box as R. sphaeroides, which, in agreement with previous work, is proposed as being the GTTCN(7)GTTC motif.