title: Interconnection of post-transcriptional regulation: The RNA-binding protein Hfq is a novel target of the Lon protease in Pseudomonas aeruginosa.
abstract: Besides being a major opportunistic human pathogen, Pseudomonas aeruginosa can be found in a wide range of environments. This versatility is linked to complex regulation, which is achieved through the action of transcriptional regulators, and post-transcriptional regulation by intracellular proteases including Lon. Indeed, lon mutants in this species show defects in motility, biofilm formation, pathogenicity and fluoroquinolone resistance. Here, the proteomic approach stable isotope labeling by amino acids in cell culture (SILAC) was used to search for novel proteolytic targets. One of the proteins that accumulated in the lon mutant was the RNA-binding protein Hfq. Further experiments demonstrated the ability of Lon to degrade Hfq in vitro. Also, overexpression of the hfq gene in the wild-type strain led to partial inhibition of swarming, swimming and twitching motilities, indicating that Hfq accumulation could contribute to the phenotypes displayed by Lon mutants. Hfq overexpression also led to the upregulation of the small regulatory RNA PhrS. Analysis of the phenotypes of strains lacking or overexpressing this sRNA indicated that the Lon protease might be indirectly regulating the levels and activity of sRNAs via Hfq. Overall, this study revealed new links in the complex regulatory chain that controls multicellular behaviours in P. aeruginosa.
authors.affiliation: Centre for Microbial Diseases and Immunity Research, University of British Columbia, 2259 Lower Mall, Vancouver BC, Canada.
authors.forename: Lucía
authors.initials: L
authors.lastname: Fernández
authors.affiliation: Centre for Microbial Diseases and Immunity Research, University of British Columbia, 2259 Lower Mall, Vancouver BC, Canada.
authors.forename: Elena B M
authors.initials: EBM
authors.lastname: Breidenstein
authors.affiliation: Centre for Microbial Diseases and Immunity Research, University of British Columbia, 2259 Lower Mall, Vancouver BC, Canada.
authors.forename: Patrick K
authors.initials: PK
authors.lastname: Taylor
authors.affiliation: Centre for Microbial Diseases and Immunity Research, University of British Columbia, 2259 Lower Mall, Vancouver BC, Canada.
authors.forename: Manjeet
authors.initials: M
authors.lastname: Bains
authors.affiliation: Centre for Microbial Diseases and Immunity Research, University of British Columbia, 2259 Lower Mall, Vancouver BC, Canada.
authors.forename: César
authors.initials: C
authors.lastname: de la Fuente-Núñez
authors.affiliation: University of British Columbia, Centre for High-Throughput Biology and Department of Biochemistry &Molecular Biology, Vancouver, BC, V6T 1Z4, Canada.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Fang
authors.affiliation: University of British Columbia, Centre for High-Throughput Biology and Department of Biochemistry &Molecular Biology, Vancouver, BC, V6T 1Z4, Canada.
authors.forename: Leonard J
authors.initials: LJ
authors.lastname: Foster
authors.affiliation: Centre for Microbial Diseases and Immunity Research, University of British Columbia, 2259 Lower Mall, Vancouver BC, Canada.
authors.forename: Robert E W
authors.initials: REW
authors.lastname: Hancock
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D035001:Host Factor 1 Protein / Q000378:metabolism*; D010641:Phenotype; D049070:Protease La / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D059748:Proteolysis; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D035001:Host Factor 1 Protein; D049070:Protease La