Preferential catabolism of the (S)-enantiomer of the herbicide napropamide mediated by the enantioselective amidohydrolase SnaH and the dioxygenase Snpd in Sphingobium sp. strain B2 机翻标题: 暂无翻译,请尝试点击翻译按钮。

来源
Environmental Microbiology
年/卷/期
Jan 2020 / 22 / 1
ISSN号
1462-2912
语言
English
作者
Huang, Junwei; Chen, Dian; Jiang, Jiandong
摘要
The (R)- and (S)-enantiomers of the chiral herbicide napropamide (NAP) show different biological activities and ecotoxicities. These two enantiomers behave differently in the environment due to enantioselective catabolism by microorganisms. However, the molecular mechanisms underlying this enantioselective catabolism remain largely unknown. In this study, the genes (snaH and snpd) involved in the catabolism of NAP were cloned from Sphingobium sp. B2, which was capable of catabolizing both NAP enantiomers. Compared with (R)-NAP, (S)-NAP was much more rapidly transformed by the amidase SnaH, which initially cleaved the amide bonds of (S)/(R)-NAP to form (S)/(R)-2-(1-naphthalenyloxy)-propanoic acid [(S)/(R)-NP] and diethylamine. The alpha-ketoglutarate-dependent dioxygenase Snpd, showing strict stereoselectivity for (S)-NP, further transformed (S)-NP to 1-naphthol and pyruvate. Molecular docking and site-directed mutagenesis analyses revealed that when the (S)-enantiomers of NAP and NP occupied the active sites, the distance between the ligand molecule and the coordination atom was shorter than that when the (R)-enantiomers occupied the active sites, which facilitated formation of the transition state complex. This study enhances our understanding of the preferential catabolism of the (S)-enantiomer of NAP on the molecular level.
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关键词/主题词
Sphingobium -- genus;Sphingobium -- strain-B2;Sphingobium -- Bacteria [05000];Sphingobium -- Microorganisms;Sphingobium -- Bacteria;Sphingobium -- Eubacteria;site-directed mutational analysis -- laboratory techniques;site-directed mutational analysis -- genetic techniques;molecular docking -- laboratory techniques;molecular docking -- mathematical and computer techniques;Sphingobium snaHgene -- catabolism;Sphingobium snpdgene -- catabolism
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