title: Reduced virulence of a hfq mutant of Pseudomonas aeruginosa O1.
abstract: The Sm-like protein Hfq has been implicated in the regulation of sigmaS-dependent and sigmaS-independent genes in E. coli and in the regulation of virulence factors in both, Yersinia enterocolitica and Brucella abortus. Here, we have studied the effect of Hfq on virulence and stress response of Pseudomonas aeruginosa (PAO1). We have constructed a PAO1hfq- mutant and a PAO1hfq-rpoS- double mutant to permit distinction between direct and indirect effects of Hfq. When compared to the wild-type and the rpoS- strains, the hfq knock out strain showed a reduced growth rate and was unable to utilize glucose as a sole carbon source. Elastase activity was 80% reduced in the hfq- mutant when compared to the wild-type or the rpoS- strain, whereas alginate production seemed to be solely affected by sigmaS. The production of catalase and pyocyanin was shown to be affected in an additive manner by both, Hfq and sigmaS. Moreover, twitching and swarming mediated by typeIV pili was shown to be impaired in the hfq- mutant. When compared to PAO1 wild-type and the rpoS- mutant, the hfq- mutant decreased virulence in Galleria mellonella by a factor of 1 x 10(4) and 5 x 10(3), respectively. Likewise, when compared to wild-type, the PAO1hfq- mutant was significantly attenuated in virulence when administered intraperitoneally in mice. These results strongly suggest that Hfq is a global regulator of PAO1 virulence and stress response which is not exclusively due to its role in stimulating the synthesis of sigmaS.
authors.affiliation: Max F. Perutz Laboratories, Department of Microbiology and Genetics, University Departments at the Vienna Biocenter, University of Vienna, Dr Bohrgasse 9, 1030 Vienna, Austria.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Sonnleitner
authors.forename: Steven
authors.initials: S
authors.lastname: Hagens
authors.forename: Frank
authors.initials: F
authors.lastname: Rosenau
authors.forename: Susanne
authors.initials: S
authors.lastname: Wilhelm
authors.forename: André
authors.initials: A
authors.lastname: Habel
authors.forename: Karl-Erich
authors.initials: KE
authors.lastname: Jäger
authors.forename: Udo
authors.initials: U
authors.lastname: Bläsi
mesh_terms: D000464:Alginates; D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D002374:Catalase / Q000096:biosynthesis; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005947:Glucose / Q000378:metabolism; D020723:Glucuronic Acid / Q000096:biosynthesis; D006603:Hexuronic Acids; D035001:Host Factor 1 Protein / Q000235:genetics* / Q000378:metabolism*; D007915:Lepidoptera / Q000382:microbiology; D017909:Levivirus / Q000254:growth & development; D008666:Metalloendopeptidases / Q000096:biosynthesis; D051379:Mice; D008807:Mice, Inbred BALB C; D009068:Movement; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism / Q000472:pathogenicity*; D011710:Pyocyanine / Q000096:biosynthesis; D012808:Sigma Factor / Q000096:biosynthesis; D014774:Virulence / Q000235:genetics*; D037521:Virulence Factors / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000464:Alginates; D001426:Bacterial Proteins; D006603:Hexuronic Acids; D035001:Host Factor 1 Protein; D012808:Sigma Factor; D037521:Virulence Factors; C069567:sigma factor KatF protein, Bacteria; D020723:Glucuronic Acid; D011710:Pyocyanine; D002374:Catalase; D008666:Metalloendopeptidases; C043859:pseudolysin, Pseudomonas aeruginosa; D005947:Glucose