A two-component monooxygenase initiates a novel 2-bromo-4-nitrophenol catabolic pathway in newly isolated Cupriavidus sp. strain NyZ375
A two-component monooxygenase initiates a novel 2-bromo-4-nitrophenol catabolic pathway in newly isolated Cupriavidus sp. strain NyZ375
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DOI：
10.1016/j.ibiod.2019.03.013
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发表时间：
2019-05
影响因子：
4.8
通讯作者：
Yang Li;Hong Liu;Ying Xu;N. Zhou
中科院分区：
文献类型：
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作者：
Yang Li;Hong Liu;Ying Xu;N. Zhou
作为农药和细胞毒素抑制剂化学中间体的重要副产物，2-溴-4-硝基苯酚（2B4NP）对水生生物具有毒性。然而，细菌培养矿化2B4NP尚未见报道。在这项研究中，Cupriavidussp。从芳香污染土壤中分离得到菌株NyZ375，并进行16S rRNA基因测序鉴定。通过氧化途径，它生长在120 μM 2B4NP上，作为唯一的碳源，释放出大约等量的亚硝酸盐。在一个4.8 kb的DNA片段中发现了三个基因（bnpABC）负责2B4NP降解的初始反应。BnpAB分别是单氧合酶和黄素还原酶组分，在NADH和FAD存在下，催化2B4NP单氧合生成溴对苯二酚（BHQ, 63%）和1,2,4-苯三醇（BT, 37%），并伴随亚硝酸盐释放。BnpC是一种羟基喹啉1,2-双加氧酶，可催化BT的环裂解氧化生成马来酰乙酸酯。副产物BHQ未被菌株NyZ375进一步降解，但在浓度为100 μM时对其生长无毒性。初步推断BnpAB与cupriavidus necatorJMP134的2,4,6-三氯酚单加氧酶TcpAX进化接近。这个新分离物的2B4NP分解代谢说明了一个不同于所有已确定的2-氯-4-硝基苯酚利用物的途径。
As a vital byproduct of chemical intermediates for pesticides and cytotoxin inhibitors, 2-bromo-4-nitrophenol (2B4NP) is toxic to aquatic life. However, bacterial cultures mineralizing 2B4NP have not been reported. In this study,Cupriavidussp. strain NyZ375 was isolated from aromatics-polluted soil and identified by 16S rRNA gene sequencing. Via an oxidative pathway, it grows on 120 μM 2B4NP as the only carbon source, releasing approximately equivalent amount of nitrite. Three genes (bnpABC) in a 4.8-kb DNA fragment from a draft genome was found to be responsible for the initial reactions in 2B4NP degradation. BnpAB are the monooxygenase and flavin reductase components, respectively, catalyzing the monooxygenation of 2B4NP to bromohydroquinone (BHQ, 63%) and 1,2,4-benzenetriol (BT, 37%) with concomitant nitrite release, in the presence of NADH and FAD. BnpC is a hydroxyquinol 1,2-dioxygenase catalyzing the ring-cleavage oxidation of BT to maleylacetate. The by-product BHQ was not further degraded by strain NyZ375 but was not toxic to its growth at a concentration of 100 μM. It can be tentatively concluded that BnpAB is evolutionary close to the 2,4,6-trichlorophenol monooxygenase TcpAX fromCupriavidus necatorJMP134. The 2B4NP catabolism by this new isolate illustrates a pathway distinct from those of all identified 2-chloro-4-nitrophenol utilizers.