Activation and catalysis of the di-heme cytochrome c peroxidase from Paracoccus pantotrophus.
Bacterial cytochrome c peroxidases contain an electron transferring (E) heme domain and a peroxidatic (P) heme domain. All but one of these enzymes are isolated in an inactive oxidized state and require reduction of the E heme by a small redox donor protein in order to activate the P heme. Here we present the structures of the inactive oxidized and active mixed valence enzyme from Paracoccus pantotrophus. Chain flexibility in the former, as expressed by the crystallographic temperature factors, is strikingly distributed in certain loop regions, and these coincide with the regions of conformational change that occur in forming the active mixed valence enzyme. On the basis of these changes, we postulate a series of events that occur to link the trigger of the electron entering the E heme from either pseudoazurin or cytochrome c(550) and the dissociation of a coordinating histidine at the P heme, which allows substrate access.
Echalier
Aude
A
Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
Goodhew
Celia F
CF
Pettigrew
Graham W
GW
Fülöp
Vilmos
V
D000595:Amino Acid Sequence; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002384:Catalysis; D018360:Crystallography, X-Ray; D003578:Cytochrome-c Peroxidase / Q000737:chemistry* / Q000502:physiology*; D004789:Enzyme Activation / Q000502:physiology; D006418:Heme / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D006639:Histidine / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D042084:Paracoccus pantotrophus / Q000201:enzymology*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011549:Pseudomonas / Q000201:enzymology; D016415:Sequence Alignment
C031690:heme C; D006418:Heme; D006639:Histidine; D010088:Oxidoreductases; D003578:Cytochrome-c Peroxidase; C090099:diheme cytochrome c; D002118:Calcium