Transcription activation of a UV‐inducible Clostridium perfringens bacteriocin gene by a novel σ factor

Expression of the plasmid-encoded Clostridium perfringens gene for bacteriocin BCN5 was shown to depend in vivo and in vitro on the activity of UviA protein. UviA, also plasmid-encoded, proved to be an RNA polymerase sigma factor and was also partly autoregulatory. The uviA gene has two promoters; one provided a UviA-independent, basal level of gene expression while the stronger, UviA-dependent promoter was only utilized after the cell experienced DNA damage. As a result, BCN5 synthesis is induced by treatment with UV light or mitomycin C. UviA is related to a special class of sigma factors found to date only in Clostridium species and responsible for activating transcription of toxin genes in Clostridium difficile, Clostridium tetani, and Clostridium botulinum.