title: A putative twin-arginine translocation system in the phytopathogenic bacterium Xylella fastidiosa.
abstract: The twin-arginine translocation (Tat) pathway of the xylem-limited phytopathogenic bacterium Xylella fastidiosa strain 9a5c, responsible for citrus variegated chlorosis, was explored. The presence of tatA, tatB, and tatC in the X. fastidiosa genome together with a list of proteins harboring 2 consecutive arginines in their signal peptides suggested the presence of a Tat pathway. The functional Tat dependence of X. fastidiosa OpgD was examined. Native or mutated signal peptides were fused to the β-lactamase. Expression of fusion with intact signal peptides mediated high resistance to ampicillin in Escherichia coli tat+ but not in the E. coli tat null mutant. The replacement of the 2 arginines by 2 lysines prevented the export of β-lactamase in E. coli tat+, demonstrating that X. fastidiosa OpgD carries a signal peptide capable of engaging the E. coli Tat machinery. RT-PCR analysis revealed that the tat genes are transcribed as a single operon. tatA, tatB, and tatC genes were cloned. Complementation assays in E. coli devoid of all Tat or TatC components were unsuccessful, whereas X. fastidiosa Tat components led to a functional Tat translocase in E. coli TatB-deficient strain. Additional experiments implicated that X. fastidiosa TatB component could form a functional heterologous complex with the E. coli TatC component.
authors.affiliation: Unité de glycobiologie structurale et fonctionnelle, UMR USTL-CNRS 8576, IFR147, Université des sciences et technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France.
authors.forename: Luciane Prioli
authors.initials: LP
authors.lastname: Ciapina
authors.forename: Simone Cristina
authors.initials: SC
authors.lastname: Picchi
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Lacroix
authors.forename: Eliana Gertrudes de Macedo
authors.initials: EG
authors.lastname: Lemos
authors.forename: Carmen
authors.initials: C
authors.lastname: Ödberg-Ferragut
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005816:Genetic Complementation Test; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009876:Operon; D021382:Protein Sorting Signals / Q000235:genetics; D021381:Protein Transport; D020133:Reverse Transcriptase Polymerase Chain Reaction; D044167:Xylella / Q000235:genetics* / Q000378:metabolism; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D021382:Protein Sorting Signals; D001618:beta-Lactamases