title: The Pseudomonas aeruginosa lipid A deacylase: selection for expression and loss within the cystic fibrosis airway.
abstract: Lipopolysaccharide (LPS) is the major surface component of gram-negative bacteria, and a component of LPS, lipid A, is recognized by the innate immune system through the Toll-like receptor 4/MD-2 complex. Pseudomonas aeruginosa, an environmental gram-negative bacterium that opportunistically infects the respiratory tracts of patients with cystic fibrosis (CF), can synthesize various structures of lipid A. Lipid A from P. aeruginosa strains isolated from infants with CF has a specific structure that includes the removal of the 3 position 3-OH C10 fatty acid. Here we demonstrate increased expression of the P. aeruginosa lipid A 3-O-deacylase (PagL) in isolates from CF infants compared to that in environmental isolates. PagL activity was increased in environmental isolates by growth in medium limited for magnesium and decreased by growth at low temperature in laboratory-adapted strains of P. aeruginosa. P. aeruginosa PagL was shown to be an outer membrane protein by isopycnic density gradient centrifugation. Heterologous expression of P. aeruginosa pagL in Salmonella enterica serovar Typhimurium and Escherichia coli resulted in removal of the 3-OH C14 fatty acid from lipid A, indicating that P. aeruginosa PagL recognizes either 3-OH C10 or 3-OH C14. Finally, deacylated lipid A species were not observed in some clinical P. aeruginosa isolates from patients with severe pulmonary disease, suggesting that loss of PagL function can occur during long-term adaptation to the CF airway.
authors.affiliation: Department of Medicine, University of Washington, HSB T-293, Box 357710, 1959 Pacific Street N.E., Seattle, WA 98195, USA. rkernst@u.washington.edu
authors.forename: Robert K
authors.initials: RK
authors.lastname: Ernst
authors.forename: Kristin N
authors.initials: KN
authors.lastname: Adams
authors.forename: Samuel M
authors.initials: SM
authors.lastname: Moskowitz
authors.forename: Gretchen M
authors.initials: GM
authors.lastname: Kraig
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Kawasaki
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Stead
authors.forename: M Stephen
authors.initials: MS
authors.lastname: Trent
authors.forename: Samuel I
authors.initials: SI
authors.lastname: Miller
mesh_terms: D000215:Acylation; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism*; D002648:Child; D003550:Cystic Fibrosis / Q000382:microbiology* / Q000503:physiopathology; D015964:Gene Expression Regulation, Bacterial; D006639:Histidine; D006801:Humans; D008050:Lipid A / Q000378:metabolism*; D008274:Magnesium; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000235:genetics; D012137:Respiratory System / Q000382:microbiology* / Q000503:physiopathology; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D008050:Lipid A; D006639:Histidine; D002265:Carboxylic Ester Hydrolases; D008274:Magnesium