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A Novel Gene, Encoding 6-Hydroxy-3-Succinoylpyridine Hydroxylase, Involved in Nicotine Degradation by Pseudomonas putida Strain S16 ^,

Hongzhi Tang,¹ Shuning Wang,^1, Lanying Ma,^1, Xiangzhou Meng,^1, Zixin Deng,² Dake Zhang,³ Cuiqing Ma,¹ and Ping Xu^1,2*

State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, People's Republic of China,¹ Key Laboratory of Microbial Metabolism, Ministry of Education, College of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China,² Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 101300, People's Republic of China³

Received 8 November 2007/ Accepted 4 January 2008

Previous research suggested that Pseudomonas spp. may attack the pyrrolidine ring of nicotine in a way similar to mammalian metabolism, resulting in the formation of pseudooxynicotine, the direct precursor of a potent tobacco-specific lung carcinogen. In addition, the subsequent intermediates, 6-hydroxy-3-succinoylpyridine (HSP) and 2,5-dihydroxypyridine (DHP) in the Pseudomonas nicotine degradation pathway are two important precursors for drug syntheses. However, there is little information on the molecular mechanism for nicotine degradation via the pyrrolidine pathway until now. In this study we cloned and sequenced a 4,879-bp gene cluster involved in nicotine degradation. Intermediates N-methylmyosmine, pseudooxynicotine, 3-succinoylpyridine, HSP, and DHP were identified from resting cell reactions of the transformant containing the gene cluster and shown to be identical to those of the pyrrolidine pathway reported in wild-type strain Pseudomonas putida S16. The gene for 6-hydroxy-3-succinoylpyridine hydroxylase (HSP hydroxylase) catalyzing HSP directly to DHP was cloned, sequenced, and expressed in Escherichia coli, and the purified HSP hydroxylase (38 kDa) is NADH dependent. DNA sequence analysis of this 936-bp fragment reveals that the deduced amino acid shows no similarity with any protein of known function.

Published ahead of print on 18 January 2008.

Supplemental material for this article may be found at http://aem.asm.org/.

S.W., L.M., and X.M. contributed equally to this study.