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 (P450 bisd ), ferredoxin (Fd bisd ), and ferredoxin reductase (Red bisd ). We demonstrated that P450 bisd and Fd bisd are homodimeric proteins with molecular masses of 102.3 and 19.1 kDa, respectively, by gel filtration chromatography analysis. Spectroscopic analysis of Fd bisd revealed the presence of a putidaredoxin-type [2Fe-2S] cluster. P450 bisd , in the presence of Fd bisd , Red bisd , and NADH, was able to convert BPA. The K m and k cat values for BPA degradation were 85 ؎ 4.7 M 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 P450 bisd might exhibit strict specificity. Two BPA degradation products of the P450 bisd 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.Bisphenol A (BPA) [2,2-bis(4-hydroxyphenyl)propane] is one of the industrially important compounds for production of polycarbonates, epoxy resins, and other plastics, and worldwide annual consumption of this compound is increasing. However, BPA is strongly suspected to be an endocrine disruptor (7,16,26) and exhibits slight or moderate toxicity in aquatic organisms (39). recently also reported that BPA is immunotoxic and reduces the nonspecific host defense to a level that causes acute toxicity in mice. Furthermore, Colborn and colleagues (4) reported that BPA is widely distributed in rivers, seas, streams, and soils. These reports have proposed that information about the biological conversion of BPA is useful for understanding the fate of this compound in the environment and also for establishing techniques to purge and remove BPA from the environment.Biological transformation of BPA has been reported by many researchers. In mammals, it has been established that BPA is converted to a glucuronide conjugate and a sulfate conjugate in rats (30, 31). In plants, cells of Eucalyptus perriniana and tobacco BY-2 metabolize BPA to its hydroxyl and/or glycosyl products (8, 24). However, it has been proposed that BPA in the environment is decomposed mainly by microorganisms (5, 39). Yim et al. (48) showed that in fungi BPA was metabolized to BPA-O-␤-D-glucopyranoside. Several investigators have also reported that lignin-degrading enzymes, including lignin peroxidase, manganese peroxidase, and/or laccase from basidiomycetes, react with BPA (6,9,34,44,45,46). However, i...

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