ABSTRACT: We further characterize the VirSR and RevR regulatory networks by profiling the C. perfringens strain JIR325 and its isogenic virR and revR regulatory mutants using strand-specific RNA-seq. Two independent biological replicates were sequenced for each strain, generating more than 90 million sequence reads for each RNA-seq library (wild type, 97,289,148 reads; virR mutant, 116,505,992 reads and revR mutant, 131,811,486 reads). Using the edgeR analysis package, 223 genes in the virR mutant and 88 genes in the revR mutant were found to be differentially expressed. Comparative transcriptomic analysis revealed that VirR acts as a global negative regulator, whilst RevR acts as a global positive regulator. Therefore, about 88% of the differentially expressed genes were up-regulated in the virR mutant, whereas 75% of the differentially expressed genes were down-regulated in the revR mutant. Importantly, we identified 22 genes that were regulated by both VirR and RevR. Of these genes, 18 or 82%, which included the sporulation-specific spoIVA, sigG and sigF genes, were regulated positively and negatively by RevR and VirR, respectively. Furthermore, mapped RNA-seq reads visualized as a user plot showed that there were 97 previously unannotated transcripts in the intergenic regions. These transcripts may potentially encode novel genes or small RNA molecules. This study has identified genes, antisense transcripts, and transcripts within intergenic regions and on the native plasmid, which are controlled by the VirSR or RevR regulatory system. The knowledge obtained will enable a more thorough annotation of the C. perfringens genome.
