College of Life Sciences, Huaibei Normal University, Huaibei 235000, China.
College of Life Sciences, Huaibei Normal University, Huaibei 235000, China.
J Hazard Mater. 2017 Apr 5;327:1-10. doi: 10.1016/j.jhazmat.2016.12.038. Epub 2016 Dec 21.
A natural consortium, named L1, of Rhodococcus sp. JT-3 and Brevundimonas sp. JT-9 was obtained from quizalofop-p-ethyl (QE) polluted soil. The consortium was able to use QE as a sole carbon source for growth and degraded 100mgL of QE in 60h. Strain JT-3 initiated the catabolism of QE to quizalofop acid (QA), which was used by strain JT-9 as carbon source for growth and to simultaneously feed strain JT-3. A novel esterase EstS-JT, which was responsible for the transformation of QE to QA and essential for the mineralization of QE by the consortium, was cloned from strain JT-3. EstS-JT showed low amino acid identity to other reported esterases from esterase family VIII and represents a new member of this family. The deduced amino acid sequence contained the esterase family VIII conserved motifs S-X-X-K, YSV and WAG. The purified recombinant EstS-JT displayed maximal esterase activity at 35°C and pH 7.5. An inhibitor assay, site-directed mutagenesis and 3D modeling analysis revealed that S, K and Y were essential for catalysis and probably comprised the catalytic center of EstS-JT. Additionally, EstS-JT had broad substrate specificity and was capable of hydrolyzing p-nitrophenyl esters (C-C) and various AOPP herbicides.
从精喹禾灵（QE）污染的土壤中获得了一种名为 Rhodococcus sp. JT-3 和 Brevundimonas sp. JT-9 的天然联合体（L1）。该联合体能够将 QE 作为唯一的碳源进行生长，并在 60 小时内降解 100mgL 的 QE。菌株 JT-3 启动了 QE 向精喹禾灵酸（QA）的分解代谢，而 QA 则被菌株 JT-9 用作生长的碳源，并同时为菌株 JT-3 提供养分。一种新型酯酶 EstS-JT 从菌株 JT-3 中克隆出来，它负责将 QE 转化为 QA，并且对于联合体将 QE 矿化是必不可少的。EstS-JT 与其他报道的酯酶家族 VIII 中的酯酶的氨基酸同一性较低，代表了该家族的一个新成员。推导的氨基酸序列包含酯酶家族 VIII 保守基序 S-X-X-K、YSV 和 WAG。纯化的重组 EstS-JT 在 35°C 和 pH 7.5 下显示出最大的酯酶活性。抑制剂测定、定点突变和 3D 建模分析表明，S、K 和 Y 对于催化是必需的，并且可能构成了 EstS-JT 的催化中心。此外，EstS-JT 具有广泛的底物特异性，能够水解对硝基苯酯（C-C）和各种 AOPP 除草剂。
