Paracoccus pantotrophus Pseudoazurin Is an Electron Donor to Cytochrome c Peroxidase

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• 作者：Sofia R. Pauleta ; Franç ; oise Guerlesquin ; Celia F. Goodhew ; Bart Devreese ; Jozef Van Beeumen ; Alice S. Pereira ; Isabel Moura ; and Graham W. Pettigrew
• 刊名：Biochemistry
• 出版年：2004
• 出版时间：September 7, 2004
• 年：2004
• 卷：43
• 期：35
• 页码：11214 - 11225
• 全文大小：457K
• 年卷期：v.43,no.35(September 7, 2004)
• ISSN：1520-4995

文摘

The gene for pseudoazurin was isolated from Paracoccus pantotrophus LMD 52.44 andexpressed in a heterologous system with a yield of 54.3 mg of pure protein per liter of culture. The geneand protein were shown to be identical to those from P. pantotrophus LMD 82.5. The extinction coefficientof the protein was re-evaluated and was found to be 3.00 mM^-1 cm^-1 at 590 nm. It was confirmed thatthe oxidized protein is in a weak monomer/dimer equilibrium that is ionic-strength-dependent. Thepseudoazurin was shown to be a highly active electron donor to cytochrome c peroxidase, and activityshowed an ionic strength dependence consistent with an electrostatic interaction. The pseudoazurin has avery large dipole moment, the vector of which is positioned at the putative electron-transfer site, His81,and is conserved in this position across a wide range of blue copper proteins. Binding of the peroxidaseto pseudoazurin causes perturbation of a set of NMR resonances associated with residues on the His81face, including a ring of lysine residues. These lysines are associated with acidic residues just back fromthe rim, the resonances of which are also affected by binding to the peroxidase. We propose that theseacidic residues moderate the electrostatic influence of the lysines and so ensure that specific chargeinteractions do not form across the interface with the peroxidase.