Characterization of the first step involved in enzymatic pathway for microcystin-RR biodegraded by Sphingopyxis sp. USTB-05
Characterization of the first step involved in enzymatic pathway for microcystin-RR biodegraded by Sphingopyxis sp. USTB-05
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鞘氨醇生物降解微囊藻毒素-RR 酶途径第一步的表征。
DOI：
10.1016/j.chemosphere.2011.11.030
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发表时间：
2012-03-01
期刊：
影响因子：
8.8
通讯作者：
Wang, Hui
中科院分区：
文献类型：
--
作者：
Yan, Hai;Wang, Junfeng;Wang, Hui
生物降解微囊藻毒素（MC）基因编码的酶有助于揭示微囊藻毒素基因的功能和生物降解途径。这里第一个重要的参与微囊藻毒素-RR (MC-RR) 生物降解的基因 (USTB-05-A, 1,008 bp) 是从鞘氨醇杆菌 (Sphingopyxis sp.) 中克隆出来的。 USTB-05首次以pGEX4T-1表达载体在大肠杆菌BL21(DE3)中成功表达。克隆的USTB-05-A的核苷酸序列与鞘氨醇单胞菌中报道的mlA具有92.5%的同源性。菌株 ACM-3962。包含第 26 位（丙氨酸）和第 27 位（亮氨酸）切割位点的推导氨基酸序列显示与 MlrA 的氨基酸序列有 83% 的同一性。含有 USTB-05-A 的重组大肠杆菌 BL21 (DE3) 的无细胞提取物 (CE) 对 MC-RR 具有较高的生物降解活性。 40 mg L-1 的初始 MC-RR 在 350 mg L-1 的总蛋白下在 0.25 小时内完全生物降解。源自MC-RR的产物随着HPLC谱上MC-RR峰的减少而明显出现。产物(m/z 1056.5)的分子量比MC-RR(m/z 1038.7)高18。研究结果提供了积极的证据，表明MC-RR的生物降解始于环状MC-RR的断裂，然后转化为线性MC-RR，这是Sphingopyxis sp.第一种酶催化的第一个产物。 USTB-05。 Crown 版权所有 (C) 2011 由 Elsevier Ltd 出版。保留所有权利。
Enzymes encoded by genes biodegrading microcystins (MCs) can help reveal the function of genes and biodegradation pathway of MCs. Here the first and important gene (USTB-05-A, 1,008 bp) involved in biodegradation of microcystin-RR (MC-RR) was cloned from Sphingopyxis sp. USTB-05 and firstly expressed in Escherichia coli BL21 (DE3) with an expression vector of pGEX4T-1 successfully. The nucleotide sequences of cloned USTB-05-A possessed 92.5% homology to that of mlA reported in Sphingomonas sp. strain ACM-3962. The deduced amino acid sequences containing the cleavage sites of 26th (alanine) and 27th (leucine) showed 83% identical to that of MlrA. The cell-free extract (CE) of recombinant E. coli BL21 (DE3) containing USTB-05-A had high activity for biodegrading MC-RR. Initial MC-RR of 40 mg L-1 was completely biodegraded under total protein of 350 mg L-1 within 0.25 h. A product derived from MC-RR appeared distinctly with the decrease of MC-RR peak on the profile of HPLC. The product (m/z 1056.5) had molecular weight of 18 higher than that of MC-RR (m/z 1038.7). The findings provided the positive evidences that biodegradation of MC-RR began with the breakage of cyclic MC-RR and then it was converted to linear MC-RR as the first product catalyzed by first enzyme of Sphingopyxis sp. USTB-05. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.