Organization and transcriptional regulation of myo-inositol operon in Clostridium perfringens.

myo-Inositol operon of Clostridium perfringens strain 13 consists of 13 genes with an upstream divergent regulator, iolR. Transcriptional analysis showed three separate transcripts for the operon of 15.6, 4.6 and 2.0 kb in length. iolR mutation studies showed that IolR is a negative regulator of the operon at transcriptional level. All the transcripts were induced by myo-Inositol in dose- and time-dependent manner. Glucose repressed the expression of all the transcripts of myo-Inositol operon. We also found that the operon was positively regulated by the two-component VirR/VirS system both in the presence and absence of myo-Inositol. This study shows that the global regulatory VirR/VirS system controls the expression of genes related to energy production (e.g. myo-Inositol operon) in addition to the virulence genes of C. perfringens strain 13.