title: The flagellum of Pseudomonas aeruginosa is required for resistance to clearance by surfactant protein A.
abstract: Surfactant protein A (SP-A) is an important lung innate immune protein that kills microbial pathogens by opsonization and membrane permeabilization. We investigated the basis of SP-A-mediated pulmonary clearance of Pseudomonas aeruginosa using genetically-engineered SP-A mice and a library of signature-tagged P. aeruginosa mutants. A mutant with an insertion into flgE, the gene that encodes flagellar hook protein, was preferentially cleared by the SP-A(+/+) mice, but survived in the SP-A(-/-) mice. Opsonization by SP-A did not play a role in flgE clearance. However, exposure to SP-A directly permeabilized and killed the flgE mutant, but not the wild-type parental strain. P. aeruginosa strains with mutation in other flagellar genes, as well as mucoid, nonmotile isolates from cystic fibrosis patients, were also permeabilized by SP-A. Provision of the wild-type fliC gene restored the resistance to SP-A-mediated membrane permeabilization in the fliC-deficient bacteria. In addition, non-mucoid, motile revertants of CF isolates reacquired resistance to SP-A-mediated membrane permeability. Resistance to SP-A was dependent on the presence of an intact flagellar structure, and independent of flagellar-dependent motility. We provide evidence that flagellar-deficient mutants harbor inadequate amounts of LPS required to resist membrane permeabilization by SP-A and cellular lysis by detergent targeting bacterial outer membranes. Thus, the flagellum of P. aeruginosa plays an indirect but important role resisting SP-A-mediated clearance and membrane permeabilization.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America.
authors.forename: Shiping
authors.initials: S
authors.lastname: Zhang
authors.forename: Francis X
authors.initials: FX
authors.lastname: McCormack
authors.forename: Roger C
authors.initials: RC
authors.lastname: Levesque
authors.forename: George A
authors.initials: GA
authors.lastname: O'Toole
authors.forename: Gee W
authors.initials: GW
authors.lastname: Lau
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000502:physiology*; D015153:Blotting, Western; D002463:Cell Membrane Permeability; D003550:Cystic Fibrosis / Q000382:microbiology; D005407:Flagella / Q000378:metabolism*; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008168:Lung / Q000382:microbiology / Q000473:pathology; D016676:Macrophages, Alveolar / Q000166:cytology / Q000378:metabolism / Q000382:microbiology; D051379:Mice; D008809:Mice, Inbred C3H; D018345:Mice, Knockout; D009154:Mutation / Q000235:genetics; D009504:Neutrophils / Q000166:cytology / Q000378:metabolism / Q000382:microbiology; D010587:Phagocytosis; D011552:Pseudomonas Infections / Q000235:genetics / Q000378:metabolism / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification / Q000472:pathogenicity*; D037662:Pulmonary Surfactant-Associated Protein A / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; C097681:FlgE protein, Bacteria; D008070:Lipopolysaccharides; D037662:Pulmonary Surfactant-Associated Protein A