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

作者：Sutherland Molly C; Rankin Joel A; Kranz Robert G^*

来源：Biochemistry, 2016, 55(22): 3150-3156.

DOI：10.1021/acs.biochem.6b00427

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 Fe2+ being required for attachment to CXXCH. Results provide insight into mechanisms for the oxidation and reduction of heme in vivo.

• 出版日期2016-6-7