title: Pseudomonas syringae coordinates production of a motility-enabling surfactant with flagellar assembly.
abstract: Using a sensitive assay, we observed low levels of an unknown surfactant produced by Pseudomonas syringae pv. syringae B728a that was not detected by traditional methods yet enabled swarming motility in a strain that exhibited deficient production of syringafactin, the main characterized surfactant produced by P. syringae. Random mutagenesis of the syringafactin-deficient strain revealed an acyltransferase with homology to rhlA from Pseudomonas aeruginosa that was required for production of this unidentified surfactant, subsequently characterized by mass spectrometry as 3-(3-hydroxyalkanoyloxy) alkanoic acid (HAA). Analysis of other mutants with altered surfactant production revealed that HAA is coordinately regulated with the late-stage flagellar gene encoding flagellin; mutations in genes involved in early flagellar assembly abolish or reduce HAA production, while mutations in flagellin or flagellin glycosylation genes increase its production. When colonizing a hydrated porous surface, the bacterium increases production of both flagellin and HAA. P. syringae was defective in porous-paper colonization without functional flagella and was slightly inhibited in this movement when it lacked surfactant production. Loss of HAA production in a syringafactin-deficient strain had no effect on swimming but abolished swarming motility. In contrast, a strain that lacked HAA but retained syringafactin production exhibited broad swarming tendrils, while a syringafactin-producing strain that overproduced HAA exhibited slender swarming tendrils. On the basis of further analysis of mutants altered in HAA production, we discuss its regulation in Pseudomonas syringae.
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, California, USA.
authors.forename: Adrien Y
authors.initials: AY
authors.lastname: Burch
authors.forename: Briana K
authors.initials: BK
authors.lastname: Shimada
authors.forename: Sean W A
authors.initials: SW
authors.lastname: Mullin
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Dunlap
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bowman
authors.forename: Steven E
authors.initials: SE
authors.lastname: Lindow
mesh_terms: D005407:Flagella / Q000502:physiology*; D005408:Flagellin / Q000378:metabolism; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D008124:Locomotion; D013058:Mass Spectrometry; D016254:Mutagenesis, Insertional; D044224:Pseudomonas syringae / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013501:Surface-Active Agents / Q000737:chemistry / Q000378:metabolism*
chemical_list: D013501:Surface-Active Agents; D005408:Flagellin