Cytochromes c covalently bind their heme prosthetic groups through thioether bonds between the vinyl groups of the heme and the thiols of a CXXCH motif within the protein.In Gramnegative bacteria,this process is catal...Cytochromes c covalently bind their heme prosthetic groups through thioether bonds between the vinyl groups of the heme and the thiols of a CXXCH motif within the protein.In Gramnegative bacteria,this process is catalyzed by the Ccm(cytochrome c maturation)proteins,also called System I.The Ccm proteins are found in the bacterial inner membrane,but some(CcmE,CcmG,CcmH,and CcmI)also have soluble functional domains on the periplasmic face of the membrane.Elucidation of the mechanisms involved in the transport and relay of heme and the apo-cytochrome from the bacterial cytosol into the periplasm,and their subsequent reaction,has proved challenging due to the fact that most of the proteins involved are membrane-associated,but recent progress in understanding some key components has thrown up some surprises.In this Review,we discuss advances in our understanding of this process arising from a substrate’s point of view and from recent structural information about individual components.展开更多
基金supported in PDB's lab by the BBSRC and an EPSRC studentship to EBS.EBS is currently supported by a Chinese Academy of Sciences Fellowship for Young International Scientists(No.2010Y2SB01)a grant from the National Natural Science Foundation of China(Grant No.31150110150).
文摘Cytochromes c covalently bind their heme prosthetic groups through thioether bonds between the vinyl groups of the heme and the thiols of a CXXCH motif within the protein.In Gramnegative bacteria,this process is catalyzed by the Ccm(cytochrome c maturation)proteins,also called System I.The Ccm proteins are found in the bacterial inner membrane,but some(CcmE,CcmG,CcmH,and CcmI)also have soluble functional domains on the periplasmic face of the membrane.Elucidation of the mechanisms involved in the transport and relay of heme and the apo-cytochrome from the bacterial cytosol into the periplasm,and their subsequent reaction,has proved challenging due to the fact that most of the proteins involved are membrane-associated,but recent progress in understanding some key components has thrown up some surprises.In this Review,we discuss advances in our understanding of this process arising from a substrate’s point of view and from recent structural information about individual components.
