Molecular and biochemical characterization of 2-chloro-4-nitrophenol degradation via the 1,2,4-benzenetriol pathway in a Gram-negative bacterium
Molecular and biochemical characterization of 2-chloro-4-nitrophenol degradation via the 1,2,4-benzenetriol pathway in a Gram-negative bacterium
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革兰氏阴性细菌中 1,2,4-苯三醇途径降解 2-氯-4-硝基苯酚的分子和生化表征
DOI：
10.1007/s00253-019-09994-7
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发表时间：
2019-08
影响因子：
5
通讯作者：
Xiaoke Hu
中科院分区：
文献类型：
--
作者：
Jun Min;Lingxue Xu;Suyun Fang;Weiwei Chen;Xiaoke Hu
2-氯-4-硝基苯酚（2C4NP）是最常见的氯化硝基酚类污染物，其环境命运备受关注。据报道，革兰氏阴性细菌Cupriavidus sp. CNP-8通过1,2,4-苯三醇（BT）途径降解2C4NP，与其他革兰氏阴性2C4NP利用菌的（氯）对苯二酚途径明显不同。本文从分子、生化和遗传水平对该菌株2C4NP分解代谢的BT途径进行了表征。hnp基因簇被怀疑参与了2C4NP的分解代谢，因为在2C4NP诱导的菌株CNP-8中，hnp基因比未诱导的菌株显著上调。HnpAB是一种双组分fad依赖的单加氧酶，通过氯-1,4-苯醌催化2C4NP转化为BT， Kmof为2.7±1.1 μΜ， kcat/Kmof为0.17±0.03 μΜ-1min-1。hnpA是CNP-8在体内利用2C4NP所必需的。高效液相色谱-质谱分析证实HnpC酶可催化BT环裂解生成马来酰乙酸酯。系统发育分析表明，与其他功能鉴定的2C4NP单加氧酶相比，HnpA可能具有不同的进化起源。据我们所知，这是第一个揭示了2C4NP在革兰氏阴性菌中通过BT途径分解代谢机制的报道，增加了我们在分子和生化水平上对微生物降解2C4NP的分解代谢多样性的认识。
2-Chloro-4-nitrophenol (2C4NP) is the most common chlorinated nitrophenol pollutant, and its environmental fate is of great concern. Cupriavidus sp. CNP-8, a Gram-negative bacterium, has been reported to degrade 2C4NP via the 1,2,4-benzenetriol (BT) pathway, significantly different from the (chloro)hydroquinone pathways reported in all other Gram-negative 2C4NP-utilizers. Herein, the BT pathway of the catabolism of 2C4NP in this strain was characterized at the molecular, biochemical, and genetic levels. The hnp gene cluster was suspected to be involved in the catabolism of 2C4NP because the hnp genes are significantly upregulated in the 2C4NP-induced strain CNP-8 compared to the uninduced strain. HnpAB, a two-component FAD-dependent monooxygenase, catalyzes the conversion of 2C4NP to BT via chloro-1,4-benzoquinone, with a Kmof 2.7 ± 1.1 μΜ and a kcat/Kmof 0.17 ± 0.03 μΜ-1min-1. hnpA is necessary for strain CNP-8 to utilize 2C4NP in vivo. HnpC, a BT 1,2-dioxygenase, was proved to catalyze BT ring-cleavage with formation of maleylacetate by HPLC-MS analysis. Phylogenetic analysis indicated that HnpA likely has different evolutionary origin compared to other functionally identified 2C4NP monooxygenases. To our knowledge, this is the first report revealing the catabolic mechanism of 2C4NP via the BT pathway in a Gram-negative bacterium, increasing our knowledge of the catabolic diversity for microbial 2C4NP degradation at the molecular and biochemical level.
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DOI：
10.1016/j.ibiod.2018.12.008
发表时间：
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期刊：
International Biodeterioration & Biodegradation
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