Premium
Transport of haemin across the cytoplasmic membrane through a haemin‐specific periplasmic binding‐protein‐dependent transport system in Yersinia enterocolitica
Author(s) -
Stojiljkovic Igor,
Hantke Klaus
Publication year - 1994
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1994.tb00465.x
Subject(s) - periplasmic space , biology , yersinia enterocolitica , cytoplasm , permease , bacterial outer membrane , membrane transport protein , escherichia coli , transport protein , membrane protein , binding protein , biochemistry , microbiology and biotechnology , gene , bacteria , membrane , genetics
Summary 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.