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

ABSTRACT: Cytochromes c require covalent attachment of heme via two thioether bonds at conserved CXXCH motifs, a process accomplished in prokaryotes by eight integral membrane proteins (CcmABCDEFGH), termed System I. Heme is trafficked from inside the cell to outside (via CcmABCD) and chaperoned (holoCcmE) to the cytochrome c synthetase (CcmF/H). Purification of key System I pathway intermediates allowed the determination of heme redox potentials. The data 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. Results provide insight into mechanisms for the oxidation and reduction of heme in vivo.

SUBMITTER: Sutherland MC

PROVIDER: S-EPMC5554621 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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

Sutherland Molly C MC Rankin Joel A JA Kranz Robert G RG

Biochemistry 20160526 22

Cytochromes c require covalent attachment of heme via two thioether bonds at conserved CXXCH motifs, a process accomplished in prokaryotes by eight integral membrane proteins (CcmABCDEFGH), termed System I. Heme is trafficked from inside the cell to outside (via CcmABCD) and chaperoned (holoCcmE) to the cytochrome c synthetase (CcmF/H). Purification of key System I pathway intermediates allowed the determination of heme redox potentials. The data support a model whereby heme is oxidized to form ...[more]

PMID: 27198710

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