ABSTRACT
In a previous study (M. Sasaki, J. Maki, K. Oshiman, Y. Matsumura, and T. Tsuchido, Biodegradation 16:449-459, 2005), the cytochrome P450 monooxygenase system was shown to be involved in bisphenol A (BPA) degradation by Sphingomonas sp. strain AO1. In the present investigation, we purified the components of this monooxygenase, cytochrome P450 (P450bisd), ferredoxin (Fdbisd), and ferredoxin reductase (Redbisd). We demonstrated that P450bisd and Fdbisd are homodimeric proteins with molecular masses of 102.3 and 19.1 kDa, respectively, by gel filtration chromatography analysis. Spectroscopic analysis of Fdbisd revealed the presence of a putidaredoxin-type [2Fe-2S] cluster. P450bisd, in the presence of Fdbisd, Redbisd, and NADH, was able to convert BPA. The Km
and k
cat values for BPA degradation were 85 ± 4.7 μM and 3.9 ± 0.04 min−1, respectively. NADPH, spinach ferredoxin, and spinach ferredoxin reductase resulted in weak monooxygenase activity. These results indicated that the electron transport system of P450bisd might exhibit strict specificity. Two BPA degradation products of the P450bisd system were detected by high-performance liquid chromatography analysis and were thought to be 1,2-bis(4-hydroxyphenyl)-2-propanol and 2,2-bis(4-hydroxyphenyl)-1-propanol based on mass spectrometry-mass spectrometry analysis. This is the first report demonstrating that the cytochrome P450 monooxygenase system in bacteria is involved in BPA degradation.
Oxidase and Oxygenase Function of the Microsomal Cytochrome P450 Monooxygenase System
