Anhui Provincial Key Laboratory of Hazardous Factors and Risk Control of Agri-food Quality Safety, College of Resources and Environment, Anhui Agricultural University, Hefei 230036, China.
College of Life Sciences, Jiangxi Normal University, Nanchang 330022, China.
J Agric Food Chem. 2024 Aug 14;72(32):18067-18077. doi: 10.1021/acs.jafc.4c02268. Epub 2024 Jul 31.
Propanil residues can contaminate habitats where microbial degradation is predominant. In this study, an efficient propanil-degrading strain C-1 was isolated from paddy and identified as sp. It can completely degrade 10 μg/L-150 mg/L propanil within 0.33-10 h via the hydrolysis of the amide bond, forming 3,4-dichloroaniline. A novel bifunctional amidase, PamC, was identified in strain C-1. PamC can catalyze the hydrolysis of the amide bond of propanil to produce 3,4-dichloroaniline as well as the hydrolysis of the ester bonds of aryloxyphenoxypropionate herbicides (APPHs, clodinafop-propargyl, cyhalofop-butyl, fenoxaprop--ethyl, fluazifop--butyl, haloxyfop--methyl, and quizalofop-ethyl) to form aryloxyphenoxypropionic acids. Molecular docking and site-directed mutagenesis confirmed that the catalytic triad Lys82-Ser157-Ser181 was the active center for PamC to hydrolyze propanil and cyhalofop-butyl. This study presents a novel bifunctional amidase with capabilities for both amide and ester bond hydrolysis and enhances our understanding of the molecular mechanisms underlying the degradation of propanil and APPHs.
丙草胺残留会污染微生物降解占主导的栖息地。在这项研究中，从稻田中分离到一株高效降解丙草胺的菌株 C-1，并鉴定为 sp. 它可以通过酰胺键的水解，在 0.33-10 h 内完全降解 10 μg/L-150 mg/L 的丙草胺，生成 3,4-二氯苯胺。在菌株 C-1 中鉴定出一种新型双功能酰胺酶 PamC。PamC 可以催化丙草胺的酰胺键水解，生成 3,4-二氯苯胺，也可以催化苯氧羧酸类除草剂（APPHs，精噁唑禾草灵、精吡氟禾草灵、氰氟草酯、精恶唑禾草灵、氟吡甲禾灵、高效氟吡甲禾灵和喹禾灵）的酯键水解，生成苯氧羧酸。分子对接和定点突变证实，催化三联体 Lys82-Ser157-Ser181 是 PamC 水解丙草胺和精吡氟禾草灵的活性中心。本研究提供了一种具有酰胺和酯键水解能力的新型双功能酰胺酶，增强了我们对丙草胺和 APPHs 降解分子机制的理解。
