Identification of nicotine biotransformation intermediates by Agrobacterium tumefaciens strain S33 suggests a novel nicotine degradation pathway
Identification of nicotine biotransformation intermediates by Agrobacterium tumefaciens strain S33 suggests a novel nicotine degradation pathway
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根癌农杆菌菌株 S33 对尼古丁生物转化中间体的鉴定表明了一种新的尼古丁降解途径
DOI：
10.1007/s00253-012-4007-2
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发表时间：
2012-09-01
影响因子：
5
通讯作者：
Xu, Ping
中科院分区：
文献类型：
--
作者：
Wang, Shuning;Huang, Haiyan;Xu, Ping
烟碱是烟草中的主要生物碱，也是烟草废弃物中的主要有毒化学物质，它可以被细菌转化为羟基吡啶中间体，这些中间体是化学合成有价值药物和杀虫剂的重要前体。这种生物转化可能是利用烟草及其废弃物的一种有用方法。在这项研究中，我们探讨了尼古丁降解最近分离的根癌农杆菌S33通过确定其生长过程中的中间体尼古丁和转化过程中的尼古丁与其静息细胞。通过多种方法，包括GC-HR-MS、HPLC和ESI-Q-TOF MS分析，检测到5种羟基化吡啶中间体。令人惊讶的是，这些鉴定的中间体表明菌株S33采用了一种新的途径，该途径不同于节杆菌属和假单胞菌属中描述的两种表征途径。基于这些发现，我们提出菌株S33能够首先通过吡啶途径通过6-羟基-L-尼古丁和6-羟基-N-甲基麦斯明将尼古丁转化为6-羟基-假氧尼古丁，然后转向吡咯烷途径，形成6-羟基-3-琥珀酰基吡啶和2，5-二羟基吡啶。在菌株S33的细胞提取物和部分富集的酶中证实了关键酶烟碱脱氢酶、6-羟基-L-烟碱氧化酶和6-羟基-3-琥珀酰吡啶羟化酶的活性。细胞提取物还可通过与6-羟基-L-烟碱氧化酶的6-羟基-L-烟碱氧化反应偶联，将6-羟基-假氧烟碱转化为6-羟基-3-琥珀酰吡啶。这些结果表明，菌株S33可以通过特殊的途径将尼古丁转化为可再生的羟基吡啶中间体，其中至少有3个中间体6-羟基-L-尼古丁、6-羟基-3-琥珀酰基吡啶和2，5-二羟基吡啶具有进一步化学修饰的潜力。
Nicotine, a major alkaloid in tobacco plants and the main toxic chemical in tobacco wastes, can be transformed by bacteria into hydroxylated-pyridine intermediates, which are important precursors for the chemical synthesis of valuable drugs and insecticides. Such biotransformation could be a useful approach to utilize tobacco and its wastes. In this study, we explored nicotine degradation by a recently isolated Agrobacterium tumefaciens S33 by identifying the intermediates during its growth on nicotine and during transformation of nicotine with its resting cells. Five hydroxylated-pyridine intermediates were detected through multiple approaches, including GC-HR-MS, HPLC, and ESI-Q-TOF MS analyses. Surprisingly, these identified intermediates suggest that strain S33 employs a novel pathway that is different from the two characterized pathways described in Arthrobacter and Pseudomonas. Based on these findings, we propose that strain S33 is able to transform nicotine to 6-hydroxy-pseudooxynicotine first via the pyridine pathway through 6-hydroxy-L-nicotine and 6-hydroxy-N-methylmyosmine, and then, it turns to the pyrrolidine pathway with the formation of 6-hydroxy-3-succinoylpyridine and 2,5-dihydroxypyridine. The activities of the key enzymes, nicotine dehydrogenase, 6-hydroxy-L-nicotine oxidase, and 6-hydroxy-3-succinoylpyridine hydroxylase, were demonstrated in the cell extract of strain S33 and by partially enriched enzymes. Moreover, the cell extract could transform 6-hydroxy-pseudooxynicotine into 6-hydroxy-3-succinoylpyridine by coupling with 6-hydroxy-L-nicotine oxidation reaction by 6-hydroxy-L-nicotine oxidase. These results indicated that strain S33 can transform nicotine into renewable hydroxylated-pyridine intermediates by the special pathway, in which at least three intermediates, 6-hydroxy-L-nicotine, 6-hydroxy-3-succinoylpyridine, and 2,5-dihydroxypyridine, have potential to be further chemically modified into useful compounds.