title: PhoPQ-mediated regulation produces a more robust permeability barrier in the outer membrane of Salmonella enterica serovar typhimurium.
abstract: The PhoPQ two-component system of Salmonella enterica serovar Typhimurium produces a remodeling of the lipid A domain of the lipopolysaccharide, including the PagP-catalyzed addition of palmitoyl residue, the PmrAB-regulated addition of the cationic sugar 4-aminoarabinose and phosphoethanolamine, and the LpxO-catalyzed addition of a 2-OH group onto one of the fatty acids. By using the diffusion rates of the dyes ethidium, Nile red, and eosin Y across the outer membrane, as well as the susceptibility of cells to large, lipophilic agents, we evaluated the function of this membrane as a permeability barrier. We found that the remodeling process in PhoP-constitutive strains produces an outer membrane that serves as a very effective permeability barrier in an environment that is poor in divalent cations or that contains cationic peptides, whereas its absence in phoP null mutants produces an outer membrane severely compromised in its barrier function under these conditions. Removing combinations of the lipid A-remodeling functions from a PhoP-constitutive strain showed that the known modification reactions explain a major part of the PhoPQ-regulated changes in permeability. We believe that the increased barrier property of the remodeled bilayer is important in making the pathogen more resistant to the stresses that it encounters in the host, including attack by the cationic antimicrobial peptides. On the other hand, drug-induced killing assays suggest that the outer membrane containing unmodified lipid A may serve as a better barrier in the presence of high concentrations (e.g., 5 mM) of Mg(2+).
authors: Department of Molecular and Cell Biology, 16 Barker Hall, University of California, Berkeley, CA 94720-3202, USA.
authors: Takeshi
authors: T
authors: Murata
authors: Will
authors: W
authors: Tseng
authors: Tina
authors: T
authors: Guina
authors: Samuel I
authors: SI
authors: Miller
authors: Hiroshi
authors: H
authors: Nikaido
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000502:physiology; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology*; D002463:Cell Membrane Permeability; D004801:Eosine Yellowish-(YS) / Q000378:metabolism; D004996:Ethidium / Q000378:metabolism; D005453:Fluorescence; D017353:Gene Deletion; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability; D016254:Mutagenesis, Insertional; D010078:Oxazines / Q000378:metabolism; D012486:Salmonella typhimurium / Q000187:drug effects / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D010078:Oxazines; C409039:PmrB protein, bacteria; D014157:Transcription Factors; C081902:pmrA protein, Bacteria; C061064:PhoP protein, Bacteria; D000217:Acyltransferases; D004996:Ethidium; C044808:nile red; D004801:Eosine Yellowish-(YS)
references: Biochemistry. 2000 Sep 26;39(38):11777-87
references: 10995246
references: J Biol Chem. 2000 Oct 20;275(42):32940-9
references: 10903325
references: J Bacteriol. 2001 Oct;183(19):5554-61
references: 11544217
references: J Bacteriol. 2001 Oct;183(19):5639-44
references: 11544226
references: Microbes Infect. 2001 Nov-Dec;3(14-15):1327-34
references: 11755422
references: Mol Microbiol. 2003 Oct;50(1):219-30
references: 14507376
references: Microbiol Mol Biol Rev. 2003 Dec;67(4):593-656
references: 14665678
references: Drugs. 2004;64(2):159-204
references: 14717618
references: J Biol Chem. 2004 May 7;279(19):20044-8
references: 15014080
references: J Biol Chem. 2004 Oct 22;279(43):44966-75
references: 15319435
references: Proc Natl Acad Sci U S A. 1973 Mar;70(3):782-6
references: 4577135
references: J Bacteriol. 1974 Feb;117(2):406-16
references: 4590466
references: Biochemistry. 1976 Jun 15;15(12):2561-70
references: 820368
references: J Biol Chem. 2005 Aug 5;280(31):28186-94
references: 15951433
references: Mol Microbiol. 2005 Aug;57(4):900-12
references: 16091033
references: Cell. 2005 Aug 12;122(3):461-72
references: 16096064
references: Mol Biol Cell. 2006 Jan;17(1):498-510
references: 16251362
references: J Bacteriol. 2006 Feb;188(3):1191-5
references: 16428427
references: J Mol Biol. 2006 Mar 10;356(5):1193-206
references: 16406409
references: Mol Microbiol. 2006 Apr;60(1):39-50
references: 16556219
references: Annu Rev Biochem. 2007;76:295-329
references: 17362200
references: J Bacteriol. 2007 Jul;189(13):4911-9
references: 17483225
references: J Bacteriol. 2007 Jul;189(14):5161-9
references: 17449614
references: J Bacteriol. 2000 Jul;182(14):4077-86
references: 10869088
references: J Antimicrob Chemother. 1981 Dec;8(6):429-45
references: 7037727
references: J Lipid Res. 1985 Jul;26(7):781-9
references: 4031658
references: Annu Rev Microbiol. 1985;39:219-42
references: 2998266
references: Mol Microbiol. 1992 May;6(10):1323-33
references: 1640833
references: Nature. 1992 Aug 27;358(6389):727-33
references: 1380671
references: Microbiol Rev. 1992 Sep;56(3):395-411
references: 1406489
references: Mol Microbiol. 1992 Nov;6(22):3289-97
references: 1484485
references: J Bacteriol. 1993 Oct;175(19):6299-313
references: 8407802
references: Mol Microbiol. 1995 Apr;16(2):271-8
references: 7565089
references: Gene. 1996 Feb 22;169(1):47-52
references: 8635748
references: J Bacteriol. 1996 Oct;178(19):5803-5
references: 8824631
references: Science. 1997 Apr 11;276(5310):250-3
references: 9092473
references: J Bacteriol. 1997 Nov;179(22):7040-5
references: 9371451
references: Mol Microbiol. 1998 Mar;27(6):1171-82
references: 9570402
references: Cell. 1998 Oct 16;95(2):189-98
references: 9790526
references: Mol Microbiol. 2005 Jan;55(2):425-40
references: 15659161
references: J Bacteriol. 2005 May;187(10):3391-9
references: 15866924