Regulatory Mechanism of Nicotine Degradation in <italic toggle="yes">Pseudomonas putida</italic>

ABSTRACT Nicotine, a toxic and addictive alkaloid from tobacco, is an environmental pollutant in areas near cigarette production facilities. Over the last decade, our group has studied, in depth, the pyrrolidine pathway of nicotine degradation in Pseudomonas putida S16. However, little is known rega...

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Autores principales:	Haiyang Hu, Lijuan Wang, Weiwei Wang, Geng Wu, Fei Tao, Ping Xu, Zixin Deng, Hongzhi Tang
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2019
Materias:	biodegradation metabolic regulation nicotinamide Pseudomonas transcription repressor Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/bb5bf9976d3a433db2726b015e670485
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spelling	oai:doaj.org-article:bb5bf9976d3a433db2726b015e6704852021-11-15T15:55:25ZRegulatory Mechanism of Nicotine Degradation in <italic toggle="yes">Pseudomonas putida</italic>10.1128/mBio.00602-192150-7511https://doaj.org/article/bb5bf9976d3a433db2726b015e6704852019-06-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00602-19https://doaj.org/toc/2150-7511ABSTRACT Nicotine, a toxic and addictive alkaloid from tobacco, is an environmental pollutant in areas near cigarette production facilities. Over the last decade, our group has studied, in depth, the pyrrolidine pathway of nicotine degradation in Pseudomonas putida S16. However, little is known regarding whole mechanism(s) regulating transcription of the nicotine degradation pathway gene cluster. In the present study, we comprehensively elucidate an overall view of the NicR2-mediated two-step mechanism regulating 3-succinoyl-pyridine (SP) biotransformation, which involves the association of free NicR2 with two promoters and the dissociation of NicR2 from the NicR2-promoter complex. NicR2 can bind to another promoter, Pspm, and regulate expression of the nicotine-degrading genes in the middle of nic2 gene cluster, which are not controlled by the previously reported Phsp promoter. We identified the function of the inverted repeat bases on the two promoters responsible for NicR2 binding and found out that the –35/–10 motif for RNA polymerase is overlapped by the NicR2 binding site. We clarify the exact role of 6-hydroxy-3-succinoyl-pyridine (HSP), which acts as an antagonist and may prevent binding of free NicR2 to the promoters but cannot release NicR2 from the promoters. Finally, a regulatory model is proposed, which consists of three parts: the interaction between NicR2 and two promoters (Pspm and Phsp), the interaction between NicR2 and two effectors (HSP and SP), and the interaction between NicR2 and RNA polymerase. IMPORTANCE We report the entire process underlying the NicR2 regulatory mechanism from association between free NicR2 and two promoters to dissociation of the NicR2-promoter complex. NicR2 can bind to another promoter, Pspm, which controls expression of nicotine-degrading genes that are not controlled by the Phsp promoter. We identified specific nucleotides of the Pspm promoter responsible for NicR2 binding. HSP was further demonstrated as an antagonist, which prevents the binding of NicR2 to the Pspm and Phsp promoters, by locking NicR2 in the derepression conformation. The competition between NicR2 and RNA polymerase is essential to initiate transcription of nicotine-degrading genes. This study extends our understanding of molecular mechanisms in biodegradation of environmental pollutants and toxicants.Haiyang HuLijuan WangWeiwei WangGeng WuFei TaoPing XuZixin DengHongzhi TangAmerican Society for Microbiologyarticlebiodegradationmetabolic regulationnicotinamidePseudomonastranscription repressorMicrobiologyQR1-502ENmBio, Vol 10, Iss 3 (2019)
institution	DOAJ
collection	DOAJ
language	EN
topic	biodegradation metabolic regulation nicotinamide Pseudomonas transcription repressor Microbiology QR1-502
spellingShingle	biodegradation metabolic regulation nicotinamide Pseudomonas transcription repressor Microbiology QR1-502 Haiyang Hu Lijuan Wang Weiwei Wang Geng Wu Fei Tao Ping Xu Zixin Deng Hongzhi Tang Regulatory Mechanism of Nicotine Degradation in <italic toggle="yes">Pseudomonas putida</italic>
description	ABSTRACT Nicotine, a toxic and addictive alkaloid from tobacco, is an environmental pollutant in areas near cigarette production facilities. Over the last decade, our group has studied, in depth, the pyrrolidine pathway of nicotine degradation in Pseudomonas putida S16. However, little is known regarding whole mechanism(s) regulating transcription of the nicotine degradation pathway gene cluster. In the present study, we comprehensively elucidate an overall view of the NicR2-mediated two-step mechanism regulating 3-succinoyl-pyridine (SP) biotransformation, which involves the association of free NicR2 with two promoters and the dissociation of NicR2 from the NicR2-promoter complex. NicR2 can bind to another promoter, Pspm, and regulate expression of the nicotine-degrading genes in the middle of nic2 gene cluster, which are not controlled by the previously reported Phsp promoter. We identified the function of the inverted repeat bases on the two promoters responsible for NicR2 binding and found out that the –35/–10 motif for RNA polymerase is overlapped by the NicR2 binding site. We clarify the exact role of 6-hydroxy-3-succinoyl-pyridine (HSP), which acts as an antagonist and may prevent binding of free NicR2 to the promoters but cannot release NicR2 from the promoters. Finally, a regulatory model is proposed, which consists of three parts: the interaction between NicR2 and two promoters (Pspm and Phsp), the interaction between NicR2 and two effectors (HSP and SP), and the interaction between NicR2 and RNA polymerase. IMPORTANCE We report the entire process underlying the NicR2 regulatory mechanism from association between free NicR2 and two promoters to dissociation of the NicR2-promoter complex. NicR2 can bind to another promoter, Pspm, which controls expression of nicotine-degrading genes that are not controlled by the Phsp promoter. We identified specific nucleotides of the Pspm promoter responsible for NicR2 binding. HSP was further demonstrated as an antagonist, which prevents the binding of NicR2 to the Pspm and Phsp promoters, by locking NicR2 in the derepression conformation. The competition between NicR2 and RNA polymerase is essential to initiate transcription of nicotine-degrading genes. This study extends our understanding of molecular mechanisms in biodegradation of environmental pollutants and toxicants.
format	article
author	Haiyang Hu Lijuan Wang Weiwei Wang Geng Wu Fei Tao Ping Xu Zixin Deng Hongzhi Tang
author_facet	Haiyang Hu Lijuan Wang Weiwei Wang Geng Wu Fei Tao Ping Xu Zixin Deng Hongzhi Tang
author_sort	Haiyang Hu
title	Regulatory Mechanism of Nicotine Degradation in <italic toggle="yes">Pseudomonas putida</italic>
title_short	Regulatory Mechanism of Nicotine Degradation in <italic toggle="yes">Pseudomonas putida</italic>
title_full	Regulatory Mechanism of Nicotine Degradation in <italic toggle="yes">Pseudomonas putida</italic>
title_fullStr	Regulatory Mechanism of Nicotine Degradation in <italic toggle="yes">Pseudomonas putida</italic>
title_full_unstemmed	Regulatory Mechanism of Nicotine Degradation in <italic toggle="yes">Pseudomonas putida</italic>
title_sort	regulatory mechanism of nicotine degradation in <italic toggle="yes">pseudomonas putida</italic>
publisher	American Society for Microbiology
publishDate	2019
url	https://doaj.org/article/bb5bf9976d3a433db2726b015e670485
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Regulatory Mechanism of Nicotine Degradation in <italic toggle="yes">Pseudomonas putida</italic>

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