title: The mitochondrial cytochrome c N-terminal region is critical for maturation by holocytochrome c synthase.
abstract: The covalent attachment of heme to mitochondrial cytochrome c is catalysed by holocytochrome c synthase (HCCS, also called heme lyase). How HCCS functions and recognises the substrate apocytochrome is unknown. Here we have examined HCCS recognition of a chimeric substrate comprising a short mitochondrial cytochrome c N-terminal region with the C-terminal sequence, including the CXXCH heme-binding motif, of a bacterial cytochrome c that is not otherwise processed by HCCS. Heme attachment to the chimera demonstrates the importance of the N-terminal region of the cytochrome. A series of variants of a mitochondrial cytochrome c with amino acid replacements in the N-terminal region have narrowed down the specificity determinants, providing insight into HCCS substrate recognition.
authors.affiliation: Department of Biochemistry, University of Oxford, Oxford, United Kingdom. julie.stevens@bioch.ox.ac.uk
authors.forename: Julie M
authors.initials: JM
authors.lastname: Stevens
authors.forename: Yulin
authors.initials: Y
authors.lastname: Zhang
authors.forename: Gajanthan
authors.initials: G
authors.lastname: Muthuvel
authors.forename: Katharine A
authors.initials: KA
authors.lastname: Sam
authors.forename: James W A
authors.initials: JW
authors.lastname: Allen
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Ferguson
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001665:Binding Sites; D045304:Cytochromes c / Q000737:chemistry / Q000378:metabolism*; D006418:Heme / Q000378:metabolism; D020035:Holoenzymes; D008190:Lyases / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D020035:Holoenzymes; D024101:Mitochondrial Proteins; D006418:Heme; D045304:Cytochromes c; D008190:Lyases; C031581:cytochrome C synthetase