title: Transport of haemin across the cytoplasmic membrane through a haemin-specific periplasmic binding-protein-dependent transport system in Yersinia enterocolitica.
abstract: The Yersinia enterocolitica O:8 periplasmic binding-protein-dependent transport (PBT) system for haemin was cloned and characterized. It consisted of four proteins: the periplasmic haemin-binding protein HemT, the haemin permease protein HemU, the ATP-binding hydrophilic protein HemV and the putative haemin-degrading protein HemS. Y. enterocolitica strains mutated in hemU or hemV genes were unable to use haemin as an iron source whereas those mutated in the hemT gene were able to use haemin as an iron source. As Escherichia coli strains expressing only the haemin outer membrane receptor protein HemR from Y. enterocolitica were capable of using haemin as an iron source the existence of an E. coli K-12 haemin-specific PBT system is postulated. The first gene in the Y. enterocolitica haemin-specific PBT system encoded a protein, HemS, which is probably involved in the degradation of haemin in the cytoplasm. The presence of the hemS gene was necessary to prevent haemin toxicity in E. coli strains that accumulate large amounts of haemin in the cytoplasm. We propose a model of haemin utilization in Y. enterocolitica in which HemT, HemU and HemV proteins transport haemin into the cytoplasm where it is degraded by HemS thereby liberating the iron.
authors.affiliation: Lehrstuhl für Mikrobiologie II, Tübingen, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Stojiljkovic
authors.forename: K
authors.initials: K
authors.lastname: Hantke
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000251:Adenosine Triphosphatases; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial / Q000235:genetics; D005816:Genetic Complementation Test; D006427:Hemin / Q000378:metabolism* / Q000494:pharmacology; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010088:Oxidoreductases; D033902:Periplasmic Binding Proteins; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D015008:Yersinia enterocolitica / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; C050021:BtuC peptide, E coli; C050022:BtuD peptide, E coli; C050023:BtuE protein, E coli; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C090995:HemS protein, Yersinia enterocolitica; C090996:HemU protein, Yersinia enterocolitica; C090997:HemV protein, Yersinia enterocolitica; D026901:Membrane Transport Proteins; D033902:Periplasmic Binding Proteins; D006427:Hemin; D010088:Oxidoreductases; D000251:Adenosine Triphosphatases