title: A periplasmic thioredoxin-like protein plays a role in defense against oxidative stress in Neisseria gonorrhoeae.
abstract: Thioredoxin-like proteins of the TlpA/ResE/CcmG subfamily are known to face the periplasm in gram-negative bacteria. Using the tlpA gene of Bradyrhizobium japonicum as a query, we identified a locus (NGO1923) in Neisseria gonorrhoeae that encodes a thioredoxin-like protein (NG_TlpA). Bioinformatics analysis indicated that the predicted NG_TlpA protein contained a cleavable signal peptide at the N terminus, and secondary structure analysis identified a thioredoxin fold with a helical insertion (approximately 25 residues), similar to that found in B. japonicum TlpA but absent in cytoplasmic thioredoxins. Biochemical characterization of a recombinant form of NG_TlpA revealed a standard redox potential (E0') of -206 mV. This property and the observation that the oxidized form of the protein exhibited greater thermal stability than the reduced species indicated that NG_TlpA is a reducing thioredoxin and not an oxidizing thiol-disulfide oxidoreductase like DsbA. The thioredoxin activity of NG_TlpA was confirmed in an insulin disulfide reduction assay. A tlpA mutant of N. gonorrhoeae strain 1291 was found to be highly sensitive to oxidative killing by paraquat and hydrogen peroxide, indicating an antioxidant role for the NG_TlpA in this bacterium. The tlpA mutant also exhibited reduced intracellular survival in human primary cervical epithelial cells.
authors.affiliation: School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane 4072, Australia.
authors.forename: Maud E S
authors.initials: ME
authors.lastname: Achard
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Hamilton
authors.forename: Tarek
authors.initials: T
authors.lastname: Dankowski
authors.forename: Begoña
authors.initials: B
authors.lastname: Heras
authors.forename: Mark S
authors.initials: MS
authors.lastname: Schembri
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Edwards
authors.forename: Michael P
authors.initials: MP
authors.lastname: Jennings
authors.forename: Alastair G
authors.initials: AG
authors.lastname: McEwan
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002460:Cell Line; D005798:Genes, Bacterial; D006801:Humans; D008969:Molecular Sequence Data; D009344:Neisseria gonorrhoeae / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology*; D033903:Periplasmic Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013879:Thioredoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D033903:Periplasmic Proteins; D013879:Thioredoxins
references.citation: Nat Protoc. 2009;4(3):363-71
references.pmid: 19247286
references.citation: FEBS Lett. 2003 Jul 10;546(2-3):411-5
references.pmid: 12832079
references.citation: Mol Microbiol. 2001 Jun;40(5):1175-86
references.pmid: 11401721
references.citation: Proc Natl Acad Sci U S A. 1994 Jul 19;91(15):7017-21
references.pmid: 8041738
references.citation: J Biol Chem. 1979 Sep 25;254(18):9113-9
references.pmid: 39074
references.citation: Microbiol Mol Biol Rev. 2006 Jun;70(2):344-61
references.pmid: 16760307
references.citation: J Mol Biol. 1990 Mar 5;212(1):167-84
references.pmid: 2181145
references.citation: Clin Microbiol Rev. 2004 Oct;17(4):965-81, table of contents
references.pmid: 15489357
references.citation: J Infect Dis. 2009 Jul 15;200(2):273-8
references.pmid: 19527171
references.citation: J Bacteriol. 2005 Jun;187(12):3921-30
references.pmid: 15937154
references.citation: Structure. 1995 Mar 15;3(3):245-50
references.pmid: 7788290
references.citation: Biochem J. 1991 Apr 15;275 ( Pt 2):341-8
references.pmid: 2025221
references.citation: Biochemistry. 1993 May 18;32(19):5083-92
references.pmid: 8494885
references.citation: Protein Sci. 1998 May;7(5):1233-44
references.pmid: 9605329
references.citation: Nat Rev Microbiol. 2009 Mar;7(3):215-25
references.pmid: 19198617
references.citation: Annu Rev Microbiol. 2001;55:21-48
references.pmid: 11544348
references.citation: Microbiology (Reading). 2004 Sep;150(Pt 9):2993-3000
references.pmid: 15347757
references.citation: Annu Rev Biochem. 2003;72:111-35
references.pmid: 12524212
references.citation: J Mol Biol. 2001 Aug 31;311(5):1037-48
references.pmid: 11531338
references.citation: Biochem J. 2003 Aug 1;373(Pt 3):865-73
references.pmid: 12720546
references.citation: Mol Microbiol. 1995 Nov;18(4):729-40
references.pmid: 8817494
references.citation: J Mol Biol. 2004 Jul 16;340(4):783-95
references.pmid: 15223320
references.citation: Microbiology (Reading). 2000 Apr;146 ( Pt 4):967-979
references.pmid: 10784055
references.citation: Antioxid Redox Signal. 2007 Jan;9(1):25-47
references.pmid: 17115886
references.citation: Annu Rev Biochem. 1985;54:237-71
references.pmid: 3896121
references.citation: J Biol Chem. 2006 Oct 27;281(43):32668-75
references.pmid: 16926157
references.citation: Mol Microbiol. 2007 Jan;63(1):54-68
references.pmid: 17140413
references.citation: Protein Sci. 1993 May;2(5):717-26
references.pmid: 8495194
references.citation: J Biol Chem. 2008 Jan 11;283(2):824-32
references.pmid: 18003611
references.citation: J Infect Dis. 2009 Jan 15;199(2):227-35
references.pmid: 19032106
references.citation: J Biol Chem. 2007 Sep 28;282(39):28823-28833
references.pmid: 17675287
references.citation: Biochem J. 2001 Apr 1;355(Pt 1):51-8
references.pmid: 11256948
references.citation: Cell Mol Life Sci. 2006 Jul;63(14):1642-8
references.pmid: 16786221
references.citation: Proc Natl Acad Sci U S A. 2002 Jul 23;99(15):10108-13
references.pmid: 12096194
references.citation: Cell. 2000 Nov 22;103(5):769-79
references.pmid: 11114333
references.citation: Anal Biochem. 1989 Nov 1;182(2):319-26
references.pmid: 2610349
references.citation: EMBO J. 1993 Sep;12(9):3373-83
references.pmid: 8253065