Interspecies complementation of Escherichia coli ccm mutants: CcmE (CycJ) from Bradyrhizobium japonicum acts as a heme chaperone during cytochrome c maturation.
Biogenesis of c-type cytochromes in alpha- and gamma-proteobacteria requires the function of a set of orthologous genes (ccm genes) that encode specific maturation factors. The Escherichia coli CcmE protein is a periplasmic heme chaperone. The membrane protein CcmC is required for loading CcmE with heme. By expressing CcmE (CycJ) from Bradyrhizobium japonicum in E. coli we demonstrated that heme is bound covalently to this protein at a strictly conserved histidine residue. The B. japonicum homologue can transfer heme to apocytochrome c in E. coli, suggesting that it functions as a heme chaperone. CcmC (CycZ) from B. japonicum expressed in E. coli was capable of inserting heme into CcmE.
Schulz
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Institut für Mikrobiologie, Eidgenössische Technische Hochschule, CH 8092 Zürich, Switzerland.
Thöny-Meyer
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D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D020369:Bradyrhizobium / Q000235:genetics / Q000378:metabolism*; D003574:Cytochrome c Group / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005816:Genetic Complementation Test; D006418:Heme / Q000378:metabolism*; D006420:Hemeproteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism*; D016296:Mutagenesis; D011499:Protein Processing, Post-Translational
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C492058:CcmC protein, E coli; C116246:CcmC protein, bacteria; C115384:CcmE protein, E coli; C093104:CycJ protein, Bacteria; D003574:Cytochrome c Group; D029968:Escherichia coli Proteins; D006420:Hemeproteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D006418:Heme