Identification of two combined genes responsible for dechlorination of 3,5,6-trichloro-2-pyridinol (TCP) in Cupriavidus pauculus P2.

Dehalogenation is an important mechanism for degrading and detoxifying halogenated aromatics in microbes. However, the biochemical and molecular mechanisms of dehalogenation of 3,5,6-trichloro-2-pyridinol (TCP) are still unknown. In this study, a novel 6012 bp gene cluster was cloned from TCP-degrading strain P2, which was responsible for the dehalogenation of TCP. The cluster included a monooxygenase gene (tcpA1), a flavin reductase gene (tcpB1), tcpR1, orf1 and orf2. TcpA1 and TcpB1 were indispensable for the dehalogenation of TCP. They worked together to catalyze the dehalogenation of three chlorine of TCP, and generated a more readily biodegradable product of 3,6-dihydroxypyridine-2,5-dione. TcpA1 displayed the highest activity against TCP at 40°C and at pH 8.0. Cu(2+), Zn(2+), and Hg(2+) significantly inhibited enzyme activity. To the best of our knowledge, this is the first report on a gene cluster responsible for TCP degradation.