title: A novel and ubiquitous system for membrane targeting and secretion of cofactor-containing proteins.
abstract: We report the identification of the proteins encoded by the mttABC operon (formerly yigTUW), which mediate a novel Sec-independent membrane targeting and translocation system in Escherichia coli that interacts with cofactor-containing redox proteins having a S/TRRXFLK "twin arginine" leader motif. A pleiotropic-negative mutant in mttA prevents the periplasmic localization of twin arginine redox enzymes, including nitrate reductase (NapA) and trimethylamine N-oxide reductase (TorA). The mutation also prevents the correct localization of the integral membrane molybdoenzyme dimethylsulfoxide reductase (DmsABC). The DmsA subunit has a twin arginine leader. Proteins with a Sec-dependent leader or which assemble spontaneously in the membrane are not affected by this mutation. MttA, B, and C are members of a large family of related sequences extending from archaebacteria to higher eukaryotes.
authors.affiliation: Department of Biochemistry, University of Alberta, Edmonton, Canada.
authors.forename: J H
authors.initials: JH
authors.lastname: Weiner
authors.forename: P T
authors.initials: PT
authors.lastname: Bilous
authors.forename: G M
authors.initials: GM
authors.lastname: Shaw
authors.forename: S P
authors.initials: SP
authors.lastname: Lubitz
authors.forename: L
authors.initials: L
authors.lastname: Frost
authors.forename: G H
authors.initials: GH
authors.lastname: Thomas
authors.forename: J A
authors.initials: JA
authors.lastname: Cole
authors.forename: R J
authors.initials: RJ
authors.lastname: Turner
mesh_terms: D055516:2S Albumins, Plant; D000595:Amino Acid Sequence; D001120:Arginine / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005838:Genotype; D007506:Iron-Sulfur Proteins; D007700:Kinetics; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000378:metabolism*; D009876:Operon; D010088:Oxidoreductases / Q000378:metabolism*; D000587:Oxidoreductases Acting on CH-NH Group Donors; D010940:Plant Proteins / Q000378:metabolism*; D010957:Plasmids; D016133:Polymerase Chain Reaction; D021382:Protein Sorting Signals / Q000737:chemistry; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D016415:Sequence Alignment
chemical_list: D055516:2S Albumins, Plant; D029968:Escherichia coli Proteins; D007506:Iron-Sulfur Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D010940:Plant Proteins; D021382:Protein Sorting Signals; D011994:Recombinant Proteins; C050363:napin protein, Brassica napus; D001120:Arginine; D010088:Oxidoreductases; C021567:methylamine dehydrogenase; D000587:Oxidoreductases Acting on CH-NH Group Donors; D009247:NADH, NADPH Oxidoreductases; D009565:Nitrate Reductases; D050901:Nitrate Reductase; C494404:napA protein, E coli; C045664:dimethyl sulfoxide reductase