title: Roles of the twin-arginine translocase and associated chaperones in the biogenesis of the electron transport chains of the human pathogen Campylobacter jejuni.
abstract: The zoonotic pathogen Campylobacter jejuni NCTC 11168 uses a complex set of electron transport chains to ensure growth with a variety of electron donors and alternative electron acceptors, some of which are known to be important for host colonization. Many of the key redox proteins essential for electron transfer in this bacterium have N-terminal twin-arginine translocase (TAT) signal sequences that ensure their transport across the cytoplasmic membrane in a folded state. By comparisons of 2D gels of periplasmic extracts, gene fusions and specific enzyme assays in wild-type, tatC mutant and complemented strains, we experimentally verified the TAT dependence of 10 proteins with an N-terminal twin-arginine motif. NrfH, which has a TAT-like motif (LRRKILK), was functional in nitrite reduction in a tatC mutant, and was correctly rejected as a TAT substrate by the tatfind and TatP prediction programs. However, the hydrogenase subunit HydA is also rejected by tatfind, but was shown to be TAT-dependent experimentally. The YedY homologue Cj0379 is the only TAT translocated molybdoenzyme of unknown function in C. jejuni; we show that a cj0379c mutant is deficient in chicken colonization and has a nitrosative stress phenotype, suggestive of a possible role for Cj0379 in the reduction of reactive nitrogen species in the periplasm. Only two potential TAT chaperones, NapD and Cj1514, are encoded in the genome. Surprisingly, despite homology to TorD, Cj1514 was shown to be specifically required for the activity of formate dehydrogenase, not trimethylamine N-oxide reductase, and was designated FdhM.
authors.affiliation: Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hitchcock
authors.affiliation: Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Hall
authors.affiliation: Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Myers
authors.affiliation: Institute of Food Research, Norwich Research Park, Colney Lane, Norwich NR4 7UA, UK.
authors.forename: Francis
authors.initials: F
authors.lastname: Mulholland
authors.affiliation: School of Veterinary Medicine and Science, The University of Nottingham, Sutton Bonnington, Loughborough LE12 2RD, UK.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Jones
authors.affiliation: Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Kelly
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D016123:Campylobacter jejuni / Q000201:enzymology* / Q000235:genetics; D002645:Chickens; D004269:DNA, Bacterial / Q000235:genetics; D004579:Electron Transport; D045222:Electron Transport Chain Complex Proteins / Q000378:metabolism; D005816:Genetic Complementation Test; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D020543:Proteome / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D045222:Electron Transport Chain Complex Proteins; D026901:Membrane Transport Proteins; D018832:Molecular Chaperones; D009573:Nitrites; D020543:Proteome; D009569:Nitric Oxide