title: The vfr gene product, required for Pseudomonas aeruginosa exotoxin A and protease production, belongs to the cyclic AMP receptor protein family.
abstract: The synthesis of exotoxin A (ETA) by Pseudomonas aeruginosa is a complex, regulated event. Several ETA putative regulatory mutants of P. aeruginosa PA103 have previously been characterized (S. E. H. West, S. A. Kaye, A. N. Hamood, and B. H. Iglewski, Infect. Immun. 62:897-903, 1994). In addition to ETA production, these mutants, PA103-15, PA103-16, and PA103-19, were also deficient in the production of protease and in regA P1 promoter activity. RegA is a positive regulator of ETA transcription. We cloned a gene, designated vfr for virulence factor regulator, that restored ETA and protease production to parental levels in these mutants. In addition, transcription from the regA P1 promoter was restored. In Escherichia coli, when vfr was overexpressed from a phage T7 promoter, a protein with an apparent molecular mass of 28.5 kDa was produced. Analysis of the deduced amino acid sequence of vfr revealed that the expected protein is 67% identical and 91% similar over a 202-amino-acid overlap to the E. coli cyclic AMP receptor protein (CAP or Crp). The cloned vfr gene complemented the beta-galactosidase- and tryptophanase-deficient phenotypes of E. coli RZ1331, a crp deletion mutant. However, the E. coli crp gene under the control of the tac promoter did not complement the ETA-deficient or protease-deficient phenotype of PA103-15 or PA103-16. The ability of vfr to restore both ETA and protease production to these mutants suggests that vfr is a global regulator of virulence factor expression in P. aeruginosa.
authors.affiliation: Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin, Madison 53706.
authors.forename: S E
authors.initials: SE
authors.lastname: West
authors.forename: A K
authors.initials: AK
authors.lastname: Sample
authors.forename: L J
authors.initials: LJ
authors.lastname: Runyen-Janecky
mesh_terms: D036002:ADP Ribose Transferases; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D001427:Bacterial Toxins; D001483:Base Sequence; D002352:Carrier Proteins; D003001:Cloning, Molecular; D002373:Cyclic AMP Receptor Protein / Q000096:biosynthesis / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D005098:Exotoxins / Q000096:biosynthesis*; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D005810:Multigene Family; D011401:Promoter Regions, Genetic / Q000235:genetics; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000472:pathogenicity; D011953:Receptors, Cyclic AMP / Q000145:classification / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000096:biosynthesis*; D014157:Transcription Factors; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A
chemical_list: D036002:ADP Ribose Transferases; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D002352:Carrier Proteins; D002373:Cyclic AMP Receptor Protein; D005098:Exotoxins; D011953:Receptors, Cyclic AMP; D011994:Recombinant Proteins; D012697:Serine Endopeptidases; D014157:Transcription Factors; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A; C072722:RegA protein, Bacteria; C091090:Vfr protein, Pseudomonas aeruginosa; C038495:Pseudomonas serine proteinase