title: The conserved tetracysteine motif in the general secretory pathway component PulE is required for efficient pullulanase secretion.
abstract: The PulE component of the pullulanase secretion pathway, a typical main terminal branch of the general secretory pathway, has a tetracysteine motif (4Cys) that is also present in almost all of the many PulE homologues, including those involved in type-IV piliation and conjugal DNA transfer. The 4Cys resembles a zinc-binding motif found in other proteins such as adenylate kinases, which may be pertinent in view of the fact that PulE has a consensus ATP-binding motif and since at least one PulE homologue has been reported to have kinase activity. In PulE, the Cys residues of this motif form scrambled intra- and intermolecular disulfide bonds when cells are disrupted. Replacement of one or more Cys of this motif by Ser reduces PulE function, but at least two adjacent Cys must be replaced to prevent intramolecular disulfide bond formation.
authors.affiliation: Unité de Génétique Moléculaire, CNRS URA 1149, Institut Pasteur, Paris, France.
authors.forename: O M
authors.initials: OM
authors.lastname: Possot
authors.forename: A P
authors.initials: AP
authors.lastname: Pugsley
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D003545:Cysteine / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D010861:Fimbriae, Bacterial / Q000737:chemistry; D005816:Genetic Complementation Test; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006090:Gram-Negative Bacteria / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D011487:Protein Conformation
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D004220:Disulfides; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C072863:PulE protein, E coli; D000255:Adenosine Triphosphate; D006026:Glycoside Hydrolases; C100181:pullulanase; D003545:Cysteine