title: Regulation of Pseudomonas aeruginosa ptxR by Vfr.
abstract: Pseudomonas aeruginosa PtxR enhances the expression of the exotoxin A gene toxA. The expression of ptxR itself, which occurs from two promoters (P1 and P2), is not completely understood. We have recently demonstrated that the ptxR upstream region contains potential binding sites for multiple regulators, including the virulence factor regulator Vfr. In this study, we identified within the ptxR upstream region, a 25 bp sequence to which Vfr specifically binds. The sequence is located 20-44 (32.5) bp 5' of the ptxR P2 promoter, and overlaps a potential binding site for the iron-starvation sigma factor PvdS. We also show that, throughout the growth cycle, deletion of vfr reduces ptxR expression from the P2 promoter in the P. aeruginosa strain PAO1 by four- to eightfold, but does not affect ptxR expression from P1. Further, loss of Vfr eliminates the PtxR-induced enhancement in the synthesis of exotoxin A and the metalloproteinase LasB. Our results suggest that Vfr modulates toxA and lasB expression in PAO1 through PtxR. A model defining the relationships between these different genes is presented.
authors.affiliation: Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: Evan
authors.initials: E
authors.lastname: Ferrell
authors.affiliation: Department of Microbiology and Immunology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Carty
authors.affiliation: Department of Microbiology and Immunology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.
authors.forename: Jane A
authors.initials: JA
authors.lastname: Colmer-Hamood
authors.affiliation: Department of Microbiology and Immunology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.
authors.forename: Abdul N
authors.initials: AN
authors.lastname: Hamood
authors.affiliation: Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: Susan E H
authors.initials: SEH
authors.lastname: West
mesh_terms: D036002:ADP Ribose Transferases / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002373:Cyclic AMP Receptor Protein / Q000235:genetics* / Q000378:metabolism; D018983:DNA Footprinting; D024202:Electrophoretic Mobility Shift Assay; D005098:Exotoxins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011550:Pseudomonas aeruginosa / Q000235:genetics*; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism; D000097668:Pseudomonas aeruginosa Exotoxin A
chemical_list: D036002:ADP Ribose Transferases; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D002373:Cyclic AMP Receptor Protein; D005098:Exotoxins; D008666:Metalloendopeptidases; D012808:Sigma Factor; D014157:Transcription Factors; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A; C093593:PvdS protein, Pseudomonas aeruginosa; C091090:Vfr protein, Pseudomonas aeruginosa; C073470:LysR protein, Bacteria; C043859:pseudolysin, Pseudomonas aeruginosa