PMID:8626316

Citation	Ba-Thein, W, Lyristis, M, Ohtani, K, Nisbet, IT, Hayashi, H, Rood, JI and Shimizu, T (1996) The virR/virS locus regulates the transcription of genes encoding extracellular toxin production in Clostridium perfringens. J. Bacteriol. 178:2514-20
Abstract	Extracellular toxin production in Clostridium perfringens is positively regulated by the two-component regulatory genes virR and virS. Northern (RNA) blots carried out with RNA preparations from the wild-type strain 13 and the isogenic virR and virS mutants TS133 and JIR4000 showed that the virR and virS genes composed an operon and were transcribed as a single 2.1-kb mRNA molecule. Primer extension analysis led to the identification of two promoters upstream of virR. Hybridization analysis of the mutants and their complemented derivatives showed that the virR/virS system positively regulated the production of alpha-toxin (or phospholipase C, theta-toxin (perfringolysin O), and kappa-toxin (collagenase) at the transcriptional level. However, the modes of regulation of these genes were shown to differ. The theta-toxin structural gene, pfoA, had both a major and a very minor promoter, with the major promoter being virR/virS dependent. The colA gene, which encodes the kappa-toxin, had two major promoters, only one of which was virR/virS-dependent. In contrast, the alpha-toxin structural gene, p1c, had only one promoter, which was shown to be partially regulated by the virR and virS genes. Comparative analysis of the virR/virS-dependent promoters did not reveal any common sequence motifs that could represent VirR-binding sites. It was concluded that either the virR/virS system modulates its effects via secondary regulatory genes that are specific for each toxin structural gene or the VirR protein does not have a single consensus binding sequence.
Links	PubMed PMC177973
Keywords	Bacterial Proteins/genetics; Bacterial Proteins/physiology; Bacterial Toxins/biosynthesis; Bacterial Toxins/genetics; Base Sequence; Clostridium perfringens/genetics; Clostridium perfringens/metabolism; Gene Expression Regulation, Bacterial/genetics; Genes, Bacterial/genetics; Molecular Sequence Data; Promoter Regions, Genetic/genetics; RNA, Bacterial/analysis; RNA, Messenger/analysis; Regulon/genetics; Transcription Factors/genetics; Transcription Factors/physiology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
CLOPE:Q8XKA0		GO:0010628: positive regulation of gene expression	ECO:0000315:		P		Figure 5. shows the diminished expression of pfoA, pfoR, colA, and plc virulence genes in TS133 virR mutant strain.	complete CACAO 5252
CLOPE:Q8XKA0	involved_in	GO:0010628: positive regulation of gene expression	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
CLOPE:I1SBA9		GO:0045893: positive regulation of transcription, DNA-dependent	ECO:0000315:		P		Table 2. shows that virS mutation in strain JIR4000 reduced transcription of genes plc, pfoA, and colA. Table 2. also shows that this reduced transcription could be rescued by plasmid-encoded virR and virS genes.	complete CACAO 5367
CLOPE:I1SBA9	involved_in	GO:0045893: positive regulation of transcription, DNA-templated	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete

References

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