Simultaneous Microcystin Degradation and Microcystis aeruginosa Inhibition with the Single Enzyme Microcystinase A
Simultaneous Microcystin Degradation and Microcystis aeruginosa Inhibition with the Single Enzyme Microcystinase A
复制标题
使用单酶微囊藻毒素酶 A 同时降解微囊藻毒素并抑制铜绿微囊藻。
DOI：
10.1021/acs.est.0c02155
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发表时间：
2020-07-21
影响因子：
11.4
通讯作者：
Feng, Lingling
中科院分区：
文献类型：
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作者：
Liu, Honglin;Guo, Xiaoliang;Feng, Lingling
有害微囊藻水华严重威胁环境生态和人类健康。微囊藻产生的微囊藻毒素（MCs）是HMB诱导和维持的强有力介质。在这项研究中，微囊藻毒素A（MlrA），具有MC降解能力的酶，成功地获得了超过90%的纯度，首次通过在大肠杆菌K12 TB 1中的过量表达。所获得的MlrA在高温和碱性条件下表现出高稳定性，同时还表现出长半衰期。MlrA选择性地抑制MC-生产微囊藻文化，但对MC-非生产集胞藻文化没有影响。通过形态学和生理学研究MlrA对微囊藻的抑制作用，探讨MlrA对微囊藻的抑制机制。MlrA通过下调微囊藻毒素生物合成途径中的相关基因，有效降解细胞外MCs，减少细胞内MCs的合成。同时，MlrA通过下调光合作用途径重要基因的表达，阻断电子传递链活性和色素合成，抑制微囊藻的光合作用。因此，MlrA通过降低微囊藻的光合能力和胞内MC含量，同时降解胞外MC来实现对微囊藻生长的抑制。在这些结果的基础上，我们提出了一个新的范例，以实现同时去除MC和HMBs使用单一的酶，其特征在于这里。
Harmful Microcystis blooms (HMBs) seriously threaten the ecology of environments and human health. Microcystins (MCs) produced by Microcystis are powerful mediators of HMB induction and maintenance. In this study, microcystinase A (MlrA), an enzyme with MC-degrading ability, was successfully obtained at over 90% purity for the first time through overexpression in Escherichia coli K12 TB1. The obtained MlrA exhibited high stability at high temperature and under alkaline conditions, while also exhibiting a long half-life. MlrA selectively inhibited MC-producing Microcystis cultures, but had no effect on MC-nonproducing Synechocystis cultures. The inhibition mechanism of MlrA against Microcystis was investigated by evaluating the morphological and physiological characteristics of cultures. MlrA effectively degraded extracellular MCs and decreased the synthesis of intracellular MCs by causing downregulation of genes involved in the microcystin biosynthesis pathway. Concomitantly, MlrA inhibited Microcystis photosynthesis by causing the downregulated expression of important photosynthesis pathway genes and interrupting electron transport chain activities and pigment synthesis. Thus, MlrA achieved the inhibition of Microcystis growth by reducing its photosynthetic capacity and intracellular MC contents, while also degrading extracellular MCs. On the basis of these results, we propose a new paradigm to achieve the simultaneous removal of MCs and HMBs using the single enzyme characterized here.