Interspecies Complementation of Escherichia coli ccm Mutants: CcmE (CycJ) from Bradyrhizobium japonicum Acts as a Heme Chaperone during Cytochrome c Maturation

AUTOR(ES)

Schulz, Henk

FONTE

American Society for Microbiology

RESUMO

Biogenesis of c-type cytochromes in α- and γ-proteobacteria requires the function of a set of orthologous genes (ccm genes) that encode specific maturation factors. The Escherichia coli CcmE protein is a periplasmic heme chaperone. The membrane protein CcmC is required for loading CcmE with heme. By expressing CcmE (CycJ) from Bradyrhizobium japonicum in E. coli we demonstrated that heme is bound covalently to this protein at a strictly conserved histidine residue. The B. japonicum homologue can transfer heme to apocytochrome c in E. coli, suggesting that it functions as a heme chaperone. CcmC (CycZ) from B. japonicum expressed in E. coli was capable of inserting heme into CcmE.

Documentos Relacionados

• Heme transfer to the heme chaperone CcmE during cytochrome c maturation requires the CcmC protein, which may function independently of the ABC-transporter CcmAB
• Biochemical and Mutational Characterization of the Heme Chaperone CcmE Reveals a Heme Binding Site
• The CcmE protein of the c-type cytochrome biogenesis system: Unusual in vitro heme incorporation into apo-CcmE and transfer from holo-CcmE to apocytochrome
• The C-Terminal Flexible Domain of the Heme Chaperone CcmE Is Important but Not Essential for Its Function
• The Bradyrhizobium japonicum cycM gene encodes a membrane-anchored homolog of mitochondrial cytochrome c.