title: Identification of two late acyltransferase genes responsible for lipid A biosynthesis in Moraxella catarrhalis.
abstract: Lipid A is a biological component of the lipo-oligosaccharide of a human pathogen, Moraxella catarrhalis. No other acyltransferases except for UDP-GlcNAc acyltransferase, responsible for lipid A biosynthesis in M. catarrhalis, have been identified. By bioinformatics, two late acyltransferase genes, lpxX and lpxL, responsible for lipid A biosynthesis were identified, and knockout mutants of each gene in M. catarrhalis strain O35E were constructed and named O35ElpxX and O35ElpxL. Structural analysis of lipid A from the parental strain and derived mutants showed that O35ElpxX lacked two decanoic acids (C10:0), whereas O35ElpxL lacked one dodecanoic (lauric) acid (C12:0), suggesting that lpxX encoded decanoyl transferase and lpxL encoded dodecanoyl transferase. Phenotypic analysis revealed that both mutants were similar to the parental strain in their toxicity in vitro. However, O35ElpxX was sensitive to the bactericidal activity of normal human serum and hydrophobic reagents. It had a reduced growth rate in broth and an accelerated bacterial clearance at 3 h (P < 0.01) or 6 h (P < 0.05) after an aerosol challenge in a murine model of bacterial pulmonary clearance. O35ElpxL presented similar patterns to those of the parental strain, except that it was slightly sensitive to the hydrophobic reagents. These results indicate that these two genes, particularly lpxX, encoding late acyltransferases responsible for incorporation of the acyloxyacyl-linked secondary acyl chains into lipid A, are important for the biological activities of M. catarrhalis.
authors.affiliation: Vaccine Research Section, National Institute on Deafness and Other Communication Disorders, Rockville, MD 20850, USA.
authors.forename: Song
authors.initials: S
authors.lastname: Gao
authors.forename: Daxin
authors.initials: D
authors.lastname: Peng
authors.forename: Wenhong
authors.initials: W
authors.lastname: Zhang
authors.forename: Artur
authors.initials: A
authors.lastname: Muszyński
authors.forename: Russell W
authors.initials: RW
authors.lastname: Carlson
authors.forename: Xin-Xing
authors.initials: XX
authors.lastname: Gu
mesh_terms: D000217:Acyltransferases / Q000235:genetics*; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D001769:Blood / Q000382:microbiology; D006801:Humans; D008050:Lipid A / Q000096:biosynthesis* / Q000737:chemistry; D051379:Mice; D008969:Molecular Sequence Data; D001936:Moraxella catarrhalis / Q000201:enzymology / Q000235:genetics*; D009154:Mutation
chemical_list: D001426:Bacterial Proteins; D008050:Lipid A; D000217:Acyltransferases; C118473:LpxL protein, bacteria
references.citation: Infect Immun. 2001 Oct;69(10):5981-90
references.pmid: 11553534
references.citation: Infect Immun. 2001 Mar;69(3):1358-63
references.pmid: 11179299
references.citation: J Biol Chem. 1997 Apr 18;272(16):10353-60
references.pmid: 9099672
references.citation: J Biol Chem. 1999 Apr 2;274(14):9677-85
references.pmid: 10092655
references.citation: Eur J Biochem. 1999 Oct;265(2):524-9
references.pmid: 10504382
references.citation: Anal Biochem. 1982 Jan 1;119(1):115-9
references.pmid: 6176137
references.citation: Antimicrob Agents Chemother. 1993 Nov;37(11):2255-60
references.pmid: 8285603
references.citation: Carbohydr Res. 1988 Apr 15;175(2):273-82
references.pmid: 2900066
references.citation: J Bacteriol. 2005 May;187(9):2939-47
references.pmid: 15838019
references.citation: Pediatr Infect Dis J. 1994 Jan;13(1 Suppl 1):S23-6; discussion S50-4
references.pmid: 8159511
references.citation: J Biol Chem. 1995 Nov 10;270(45):27151-9
references.pmid: 7592970
references.citation: Nucleic Acids Res. 2004 Jul 1;32(Web Server issue):W321-6
references.pmid: 15215403
references.citation: Annu Rev Biochem. 2007;76:295-329
references.pmid: 17362200
references.citation: Carbohydr Res. 1994 May 5;257(2):269-84
references.pmid: 7516823
references.citation: Infect Immun. 2000 Sep;68(9):4980-5
references.pmid: 10948114
references.citation: J Exp Med. 2000 Mar 20;191(6):949-60
references.pmid: 10727457
references.citation: Infect Immun. 1998 May;66(5):1891-7
references.pmid: 9573066
references.citation: Bioinformatics. 2007 Mar 15;23(6):673-9
references.pmid: 17237039
references.citation: Microb Pathog. 2003 Mar;34(3):121-30
references.pmid: 12631473
references.citation: Infect Immun. 2005 Apr;73(4):2400-10
references.pmid: 15784586
references.citation: Microbes Infect. 2000 Apr;2(5):547-59
references.pmid: 10865200
references.citation: J Clin Microbiol. 1990 Feb;28(2):182-7
references.pmid: 2107197
references.citation: Am J Respir Crit Care Med. 2005 Jul 15;172(2):195-9
references.pmid: 15805178
references.citation: Comput Appl Biosci. 1994 Dec;10(6):685-6
references.pmid: 7704669
references.citation: J Bacteriol. 2006 Feb;188(4):1381-8
references.pmid: 16452420
references.citation: Infect Immun. 1993 May;61(5):2003-10
references.pmid: 7683000
references.citation: Infect Immun. 2003 Feb;71(2):647-55
references.pmid: 12540541
references.citation: Comput Chem. 2001 Dec;26(1):51-6
references.pmid: 11765852
references.citation: J Bacteriol. 1997 Sep;179(17):5521-33
references.pmid: 9287009
references.citation: Glycobiology. 2008 Jun;18(6):447-55
references.pmid: 18337458
references.citation: Infect Immun. 2002 Feb;70(2):909-20
references.pmid: 11796626
references.citation: J Bacteriol. 1999 Feb;181(4):1099-109
references.pmid: 9973334
references.citation: Clin Microbiol Rev. 1990 Oct;3(4):293-320
references.pmid: 2121328
references.citation: J Clin Microbiol. 2005 Dec;43(12):6139-43
references.pmid: 16333114
references.citation: Infect Immun. 1992 Sep;60(9):3824-9
references.pmid: 1500191
references.citation: Microbiol Rev. 1993 Sep;57(3):655-82
references.pmid: 7504166
references.citation: Infect Immun. 2003 Nov;71(11):6426-34
references.pmid: 14573664
references.citation: Microbiol Rev. 1996 Jun;60(2):267-79
references.pmid: 8801433
references.citation: Infect Immun. 2000 Sep;68(9):5261-8
references.pmid: 10948153
references.citation: Annu Rev Biochem. 2002;71:635-700
references.pmid: 12045108
references.citation: J Biol Chem. 1996 May 17;271(20):12095-102
references.pmid: 8662613
references.citation: Plasmid. 2006 Sep;56(2):133-7
references.pmid: 16757025
references.citation: Infect Immun. 2007 Nov;75(11):5518-31
references.pmid: 17724076
references.citation: Infect Immun. 2002 Aug;70(8):4661-8
references.pmid: 12117980
references.citation: Infect Immun. 2003 Sep;71(9):4977-84
references.pmid: 12933840
references.citation: J Bacteriol. 1992 Feb;174(3):702-10
references.pmid: 1732206
references.citation: Infect Immun. 2005 Jul;73(7):4222-30
references.pmid: 15972513
references.citation: Infect Immun. 2005 Nov;73(11):7569-77
references.pmid: 16239560
references.citation: J Bacteriol. 2002 May;184(9):2379-88
references.pmid: 11948150
references.citation: Eur J Biochem. 1994 Feb 15;220(1):209-16
references.pmid: 8119289
references.citation: Clin Microbiol Rev. 2002 Jan;15(1):125-44
references.pmid: 11781271
references.citation: Carbohydr Res. 2006 Nov 6;341(15):2600-6
references.pmid: 16934238