title: Two Novel Sets of Genes Essential for Nicotine Degradation bySphingomonas melonisTY.
abstract: Nicotine is a type of environmental pollutant present in the tobacco waste that is generated during tobacco manufacturing.Sphingomonas melonisTY can utilize nicotine as a sole source of carbon, nitrogen and energy via a variant of the pyridine and pyrrolidine pathway (the VPP pathway). In this study, we report the identification of two novel sets of genes,ndrA1A2A3, andndrB1B2B3B4, which are crucial for nicotine degradation by strain TY.ndrA1A2A3andndrB1B2B3B4exhibit similarity with both nicotine dehydrogenasendhfromArthrobacter nicotinovoransand nicotine hydroxylasevppAfromOchrobactrumsp. SJY1. The transcriptional levels ofndrA1A2A3andndrB1B2B3B4in strain TY were significantly upregulated in the presence of nicotine. Furthermore,ndrA1orndrB2knockout resulted in a loss of the ability to degrade nicotine, whereas gene complementation restored the capacity of each mutant to utilize nicotine for growth. Biodegradation assays indicated that the mutant strains retained the ability to degrade the first intermediate in the pathway, 6-hydroxynicotine (6 HN). However, heterologous expression ofndrA1A2A3andndrB1B2B3B4did not confer nicotine dehydrogenase activity toE. coliDH5α,Pseudomonas putidaKT2440 orSphingomonas aquatilis. These results provide information on the VPP pathway of nicotine degradation inS. melonisTY, and we conclude that these two sets of genes have essential functions in the conversion of nicotine to 6 HN in strain TY.
authors.affiliation: Institute of Microbiology, College of Life Sciences, Zhejiang University Hangzhou, China.
authors.forename: Haixia
authors.initials: H
authors.lastname: Wang
authors.affiliation: Institute of Microbiology, College of Life Sciences, Zhejiang University Hangzhou, China.
authors.forename: Cuixiao
authors.initials: C
authors.lastname: Xie
authors.affiliation: Institute of Microbiology, College of Life Sciences, Zhejiang University Hangzhou, China.
authors.forename: Panpan
authors.initials: P
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University Shanghai, China.
authors.forename: Ning-Yi
authors.initials: NY
authors.lastname: Zhou
authors.affiliation: Institute of Microbiology, College of Life Sciences, Zhejiang University Hangzhou, China.
authors.forename: Zhenmei
authors.initials: Z
authors.lastname: Lu
keywords: Sphingomonas melonis TY; ndrA1A2A3; ndrB1B2B3B4 and nicotine dehydrogenase; nicotine