title: Characterization of genes regulated directly by the VirR/VirS system in Clostridium perfringens.
abstract: Analysis of the complete sequence of the genome of Clostridium perfringens strain 13 resulted in identification of five genes, including pfoA (encoding theta toxin) and vrr (encoding VirR/VirS-regulated RNA), with consensus VirR-binding sequences upstream of the open reading frame (ORF), suggesting that expression of these genes may be regulated directly by the two-component VirR/VirS system. To test this possibility, we examined VirR/VirS system-mediated transcriptional regulation of three genes, virT, ccp (encoding alpha-clostripain), and virU, with the novel VirR-binding sequences. Northern analysis revealed that the steady-state levels (increases or decreases in the amounts of RNA expressed) of virT, ccp, and virU mRNAs were lower in a virR mutant strain than in the wild-type strain, as were the levels of the pfoA and vrr transcripts. The consensus VirR-binding sites were located similarly relative to the transcription start sites in the virT, ccp, and virU promoters. Mutation and overexpression analyses with virT and virU revealed that the virT gene product has a negative effect on expression of pfoA and ccp, whereas the virU gene product positively affects expression of pfoA, virT, ccp, and vrr. Nonsense and frameshift mutations in the virT or virU putative ORF did not affect the regulatory functions, suggesting that virT and virU may encode RNA regulators rather than proteins. These results suggest that a complex regulatory network, perhaps involving several regulatory RNA molecules, governs the expression of the VirR/VirS regulon in C. perfringens.
authors.affiliation: Department of Infection Biology, Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan.
authors.forename: Kayo
authors.initials: K
authors.lastname: Okumura
authors.forename: Kaori
authors.initials: K
authors.lastname: Ohtani
authors.forename: Hideo
authors.initials: H
authors.lastname: Hayashi
authors.forename: Tohru
authors.initials: T
authors.lastname: Shimizu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001482:Base Composition; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D003016:Clostridium perfringens / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D016680:Genome, Bacterial; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011485:Protein Binding; D018085:Regulon
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial
references.citation: J Bacteriol. 2000 Jan;182(1):57-66
references.pmid: 10613863
references.citation: Mol Microbiol. 2002 Apr;44(1):171-9
references.pmid: 11967077
references.citation: FEMS Microbiol Lett. 2002 Mar 19;209(1):113-8
references.pmid: 12007663
references.citation: Mol Gen Genet. 1993 Jul;240(1):140-5
references.pmid: 8341259
references.citation: Trends Microbiol. 2003 Jun;11(6):280-5
references.pmid: 12823945
references.citation: Microbiol Immunol. 2000;44(6):525-8
references.pmid: 10941936
references.citation: Plasmid. 1992 May;27(3):207-19
references.pmid: 1513878
references.citation: Can J Microbiol. 1976 Jul;22(7):953-9
references.pmid: 9192
references.citation: J Biol Chem. 1981 Nov 25;256(22):11905-10
references.pmid: 6271763
references.citation: FEMS Microbiol Lett. 2003 May 16;222(1):137-41
references.pmid: 12757957
references.citation: J Med Microbiol. 1992 May;36(5):307-11
references.pmid: 1588579
references.citation: Curr Opin Microbiol. 2003 Apr;6(2):120-4
references.pmid: 12732300
references.citation: Mol Microbiol. 2000 Feb;35(4):854-64
references.pmid: 10692162
references.citation: J Bacteriol. 1996 May;178(9):2514-20
references.pmid: 8626316
references.citation: Trends Microbiol. 1999 Mar;7(3):104-10
references.pmid: 10203838
references.citation: J Bacteriol. 2004 Jun;186(11):3321-30
references.pmid: 15150217
references.citation: J Bacteriol. 1994 Mar;176(6):1616-23
references.pmid: 8132455
references.citation: Mol Microbiol. 2002 Jan;43(1):257-65
references.pmid: 11849553
references.citation: Genome Res. 2006 Aug;16(8):1031-40
references.pmid: 16825665
references.citation: J Bacteriol. 2007 Oct;189(20):7174-80
references.pmid: 17693508
references.citation: J Bacteriol. 2002 May;184(10):2587-94
references.pmid: 11976286
references.citation: Proc Natl Acad Sci U S A. 2002 Jan 22;99(2):996-1001
references.pmid: 11792842
references.citation: Mol Microbiol. 1994 Jun;12(5):761-77
references.pmid: 8052128
references.citation: Clin Microbiol Rev. 1990 Jan;3(1):66-98
references.pmid: 2404569
references.citation: J Biol Chem. 1979 Mar 10;254(5):1462-8
references.pmid: 762145
references.citation: Am J Physiol. 1981 May;240(5):C234-8
references.pmid: 6263099
references.citation: Mol Microbiol. 1995 Jan;15(2):191-202
references.pmid: 7746141