Cytochrome c assembly

@article{Mavridou2013CytochromeCA,
  title={Cytochrome c assembly},
  author={Despoina A. I. Mavridou and Stuart J Ferguson and Julie M. Stevens},
  journal={IUBMB Life},
  year={2013},
  volume={65}
}
Cytochromes c are central proteins in energy transduction processes by virtue of their functions in electron transfer in respiration and photosynthesis. They have heme covalently attached to a characteristic CXXCH motif via protein‐catalyzed post‐translational modification reactions. Several systems with diverse constituent proteins have been identified in different organisms and are required to perform the heme attachment and associated functions. The necessary steps are translocation of the… 

Protein Machineries Involved in the Attachment of Heme to Cytochrome c: Protein Structures and Molecular Mechanisms

The structural and functional properties of the main maturation apparatuses found in gram-negative and gram-positive bacteria and in the mitochondria of eukaryotic cells will be presented, dissecting the Cyt c maturation process into three functional steps: (i) heme translocation and delivery, (ii) apoCyt thioreductive pathway, and (iii) apOCyt chaperoning and heme ligation.

Heme Trafficking and Modifications during System I Cytochrome c Biogenesis: Insights from Heme Redox Potentials of Ccm Proteins.

Results provide insight into mechanisms for the oxidation and reduction of heme in vivo and support a model whereby heme is oxidized to form holoCcmE and subsequently reduced by CcmF/H for thioether formation, with Fe(2+) being required for attachment to CXXCH.

Maturation of Plastid c-type Cytochromes

While only four CCS components are needed in bacteria, at least eight components are required for plastid cytochrome c assembly, suggesting the biochemistry of thioether formation is more nuanced in the plastids system.

Investigation of the Molecular Mechanisms of the Eukaryotic Cytochrome-c Maturation System

It is shown that it is possible to convert a bacterial cytochrome as a substrate by CcHL, but the presence of the recognition sequence is not the only factor that induces the maturation of a holocytochrome by System III, which appears to be unable to assemble multiheme cytochromes c, in contrast with bacterial maturation systems.

The CcmC–CcmE interaction during cytochrome c maturation by System I is driven by protein–protein and not protein–heme contacts

The combination of in vivo site-directed mutagenesis studies and high-resolution structural techniques enabled us to determine at the residue level the mechanism for the formation of one of the key protein complexes for cytochrome c maturation by System I.

Deciphering protein–protein interactions during the biogenesis of cytochrome c oxidase from Paracoccus denitrificans

This study tentatively supports previous speculation regarding the existence of a predominantly co‐translational mechanism for cofactor insertion during COX biogenesis and extends the view towards a hypothetical ‘biogenesis complex’ by identifying two further metal‐ inserting chaperones, Surf1c and Sco, together with enzymes catalyzing heme a synthesis.

Structure-Function Analysis of the Bifunctional CcsBA Heme Exporter and Cytochrome c Synthetase

A new cysteine/heme crosslinking tool that traps endogenous heme in heme binding sites is employed and a structural model of the transmembrane regions in CcsBA is determined, leading to increased understanding of the mechanisms for heme transport and the cytochrome c synthetase function of CCSBA.

CCS2, an Octatricopeptide-Repeat Protein, Is Required for Plastid Cytochrome c Assembly in the Green Alga Chlamydomonas reinhardtii

The CCS2 protein displays seven degenerate amino acid repeats, which are variations of the octatricopeptide-repeat motif (OPR) recently recognized in several nuclear-encoded proteins controlling the maturation, stability, or translation of chloroplast transcripts.

The thioreduction component CcmG confers efficiency and the heme ligation component CcmH ensures stereo-specificity during cytochrome c maturation

CcmG confers efficiency, and CcmH ensures stereo-specificity during Ccm and present a comprehensive model for thioreduction reactions that lead to heme–apocytochrome c ligation.

Complex Oxidation of Apocytochromes c during Bacterial Cytochrome c Maturation

The cyt c-rich Gram-negative bacterium Shewanella oneidensis is used as the research model to clarify the roles of DsbA proteins in CCM and shows that in terms of the oxidation of apocyts c, DSBA proteins are an important but not critical factor, and, strikingly, oxygen is not either.
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