2VHD: Crystal Structure Of The Di-Haem Cytochrome C Peroxidase From Pseudomonas Aeruginosa - Mixed Valence Form

Citation:
Abstract
A recombinant form of the prototypic diheme bacterial cytochrome c peroxidase (BCCP) from Pseudomonas aeruginosa (PsaCCP) has been expressed in Escherichia coli and purified to homogeneity. This material was used to carry out the first integrated biochemical, spectroscopic and structural investigation of the factors leading to reductive activation of this class of enzymes. A single, tightly bound, Ca2+ ion (K = 3 x 10(10) M-1) found at the domain interface of both the fully oxidized and mixed-valence forms of the enzyme is absolutely required for catalytic activity. Reduction of the electron-transferring (high-potential) heme in the presence of Ca2+ ions triggers substantial structural rearrangements around the active-site (low-potential) heme to allow substrate binding and catalysis. The enzyme also forms a mixed-valence state in the absence of Ca2+ ions, but a combination of electronic absorption, and EPR spectroscopies suggests that under these circumstances the low potential heme remains six-coordinate, unable to bind substrate and therefore catalytically inactive. Our observations strongly suggest that the two mixed-valence forms of native PsaCCP reported previously by Foote and colleagues (Foote, N., Peterson, J., Gadsby, P., Greenwood, C., and Thomson, A. (1985) Biochem. J. 230, 227-237) correspond to the Ca2+-loaded and -depleted forms of the enzyme.
PDB ID: 2VHDDownload
MMDB ID: 62386
PDB Deposition Date: 2007/11/20
Updated in MMDB: 2012/12
Experimental Method:
x-ray diffraction
Resolution: 2.3  Å
Source Organism:
Similar Structures:
Biological Unit for 2VHD: dimeric; determined by author and by software (PQS)
Molecular Components in 2VHD
Label Count Molecule
Proteins (2 molecules)
2
Cytochrome C551 Peroxidase(Gene symbol: ccpR)
Molecule annotation
Chemicals (6 molecules)
1
4
2
2
* Click molecule labels to explore molecular sequence information.

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