title: Phosphorylation of the Pseudomonas aeruginosa response regulator AlgR is essential for type IV fimbria-mediated twitching motility.
abstract: The response regulator AlgR is required for both alginate biosynthesis and type IV fimbria-mediated twitching motility in Pseudomonas aeruginosa. In this study, the roles of AlgR signal transduction and phosphorylation in twitching motility and biofilm formation were examined. The predicted phosphorylation site of AlgR (aspartate 54) and a second aspartate (aspartate 85) in the receiver domain of AlgR were mutated to asparagine, and mutant algR alleles were introduced into the chromosome of P. aeruginosa strains PAK and PAO1. Assays of these mutants demonstrated that aspartate 54 but not aspartate 85 of AlgR is required for twitching motility and biofilm initiation. However, strains expressing AlgR D85N were found to be hyperfimbriate, indicating that both aspartate 54 and aspartate 85 are involved in fimbrial biogenesis and function. algD mutants were observed to have wild-type twitching motility, indicating that AlgR control of twitching motility is not mediated via its role in the control of alginate biosynthesis. In vitro phosphorylation assays showed that AlgR D54N is not phosphorylated by the enteric histidine kinase CheA. These findings indicate that phosphorylation of AlgR most likely occurs at aspartate 54 and that aspartate 54 and aspartate 85 of AlgR are required for the control of the molecular events governing fimbrial biogenesis, twitching motility, and biofilm formation in P. aeruginosa.
authors.affiliation: ARC Special Research Centre for Functional and Applied Genomics, Institute for Molecular Bioscience, Brisbane, Queensland 4072, Australia.
authors.forename: Cynthia B
authors.initials: CB
authors.lastname: Whitchurch
authors.forename: Tatiana E
authors.initials: TE
authors.lastname: Erova
authors.forename: Jacqui A
authors.initials: JA
authors.lastname: Emery
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Sargent
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Harris
authors.forename: Annalese B T
authors.initials: AB
authors.lastname: Semmler
authors.forename: Michael D
authors.initials: MD
authors.lastname: Young
authors.forename: John S
authors.initials: JS
authors.lastname: Mattick
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Wozniak
mesh_terms: D000464:Alginates / Q000378:metabolism; D000595:Amino Acid Sequence; D001224:Aspartic Acid / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms; D004563:Electrochemistry; D010861:Fimbriae, Bacterial / Q000378:metabolism*; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000072236:Methyl-Accepting Chemotaxis Proteins; D008969:Molecular Sequence Data; D009154:Mutation / Q000502:physiology; D010641:Phenotype; D010766:Phosphorylation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D015534:Trans-Activators
chemical_list: C110681:AlgR protein, Pseudomonas aeruginosa; D000464:Alginates; D001426:Bacterial Proteins; D006603:Hexuronic Acids; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D015534:Trans-Activators; D001224:Aspartic Acid; D020723:Glucuronic Acid