title: A bacterial cytochrome c heme lyase. CcmF forms a complex with the heme chaperone CcmE and CcmH but not with apocytochrome c.
abstract: Biogenesis of c-type cytochromes in Escherichia coli involves a number of membrane proteins (CcmA-H), which are required for the transfer of heme to the periplasmically located apocytochrome c. The pathway includes (i) covalent, transient binding of heme to the periplasmic domain of the heme chaperone CcmE; (ii) the subsequent release of heme; and (iii) transfer and covalent attachment of heme to apocytochrome c. Here, we report that CcmF is a key player in the late steps of cytochrome c maturation. We demonstrate that the conserved histidines His-173, His-261, His-303, and His-491 and the tryptophan-rich signature motif of the CcmF protein family are functionally required. Co-immunoprecipitation experiments revealed that CcmF interacts directly with the heme donor CcmE and with CcmH but not with apocytochrome c. We propose that CcmFH forms a bacterial heme lyase complex for the transfer of heme from CcmE to apocytochrome c.
authors.affiliation: Institut für Mikrobiologie, Eidgenössische Technische Hochschule, Schmelzbergstrasse 7, CH-8092 Zürich, Switzerland.
authors.forename: Qun
authors.initials: Q
authors.lastname: Ren
authors.forename: Umesh
authors.initials: U
authors.lastname: Ahuja
authors.forename: Linda
authors.initials: L
authors.lastname: Thöny-Meyer
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001059:Apoproteins / Q000378:metabolism*; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D003574:Cytochrome c Group / Q000378:metabolism*; D045304:Cytochromes c; D017931:DNA Primers / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism*; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D006420:Hemeproteins / Q000378:metabolism*; D006639:Histidine / Q000737:chemistry; D008190:Lyases / Q000737:chemistry* / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D019897:Periplasm / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D017354:Point Mutation; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D014364:Tryptophan / Q000737:chemistry
chemical_list: D001059:Apoproteins; D001425:Bacterial Outer Membrane Proteins; C115384:CcmE protein, E coli; C451399:CcmH protein, E coli; D003574:Cytochrome c Group; D017931:DNA Primers; D029968:Escherichia coli Proteins; D006420:Hemeproteins; D006418:Heme; D006639:Histidine; D014364:Tryptophan; D045304:Cytochromes c; D008190:Lyases; C031581:cytochrome C synthetase