title: A pivotal heme-transfer reaction intermediate in cytochrome c biogenesis.
abstract: c-Type cytochromes are widespread proteins, fundamental for respiration or photosynthesis in most cells. They contain heme covalently bound to protein in a highly conserved, highly stereospecific post-translational modification. In many bacteria, mitochondria, and archaea this heme attachment is catalyzed by the cytochrome c maturation (Ccm) proteins. Here we identify and characterize a covalent, ternary complex between the heme chaperone CcmE, heme, and cytochrome c. Formation of the complex from holo-CcmE occurs in vivo and in vitro and involves the specific heme-binding residues of both CcmE and apocytochrome c. The enhancement and attenuation of the amounts of this complex correlates completely with known consequences of mutations in genes for other Ccm proteins. We propose the complex is a trapped catalytic intermediate in the cytochrome c biogenesis process, at the point of heme transfer from CcmE to the cytochrome, the key step in the maturation pathway.
authors: Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom.
authors: Despoina A I
authors: DA
authors: Mavridou
authors: Julie M
authors: JM
authors: Stevens
authors: Leonie
authors: L
authors: Mönkemeyer
authors: Oliver
authors: O
authors: Daltrop
authors: Katalin
authors: K
authors: di Gleria
authors: Benedikt M
authors: BM
authors: Kessler
authors: Stuart J
authors: SJ
authors: Ferguson
authors: James W A
authors: JW
authors: Allen
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D045304:Cytochromes c / Q000096:biosynthesis* / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000096:biosynthesis* / Q000235:genetics; D006418:Heme / Q000235:genetics / Q000378:metabolism*; D006420:Hemeproteins / Q000096:biosynthesis* / Q000235:genetics; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis / Q000502:physiology*
chemical_list: D001425:Bacterial Outer Membrane Proteins; C115384:CcmE protein, E coli; D029968:Escherichia coli Proteins; D006420:Hemeproteins; D046912:Multiprotein Complexes; D006418:Heme; D045304:Cytochromes c