title: Cytochrome c biogenesis System I: an intricate process catalyzed by a maturase supercomplex?
abstract: Cytochromes c are ubiquitous heme proteins that are found in most living organisms and are essential for various energy production pathways as well as other cellular processes. Their biosynthesis relies on a complex post-translational process, called cytochrome c biogenesis, responsible for the formation of stereo-specific thioether bonds between the vinyl groups of heme b (protoporphyrin IX-Fe) and the thiol groups of apocytochromes c heme-binding site (C1XXC2H) cysteine residues. In some organisms this process involves up to nine (CcmABCDEFGHI) membrane proteins working together to achieve heme ligation, designated the Cytochrome c maturation (Ccm)-System I. Here, we review recent findings related to the Ccm-System I found in bacteria, archaea and plant mitochondria, with an emphasis on protein interactions between the Ccm components and their substrates (apocytochrome c and heme). We discuss the possibility that the Ccm proteins may form a multi subunit supercomplex (dubbed "Ccm machine"), and based on the currently available data, we present an updated version of a mechanistic model for Ccm. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6019, USA.
authors.forename: Andreia F
authors.initials: AF
authors.lastname: Verissimo
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6019, USA. Electronic address: fdaldal@sas.upenn.edu.
authors.forename: Fevzi
authors.initials: F
authors.lastname: Daldal
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019843:Archaeal Proteins / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D045304:Cytochromes c / Q000737:chemistry / Q000378:metabolism*; D045222:Electron Transport Chain Complex Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding
chemical_list: D019843:Archaeal Proteins; D001426:Bacterial Proteins; D045222:Electron Transport Chain Complex Proteins; D045304:Cytochromes c
keywords: Apocytochrome; Chaperone; Cytochrome c maturation; Membrane supercomplex; Photosynthesis and respiration; Protein–protein interactions; Rhodobacter capsulatus