ABSTRACT Comamonas
sp. strain JS765 can grow with nitrobenzene as the sole source of carbon, nitrogen, and energy. We report here the sequence of the genes encoding nitrobenzene dioxygenase (NBDO), which catalyzes the first step in the degradation of nitrobenzene by strain JS765. The components of NBDO were designated Reductase
NBZ
, Ferredoxin
NBZ
, Oxygenase
NBZα
, and Oxygenase
NBZβ
, with the gene designations
nbzAa
,
nbzAb
,
nbzAc
, and
nbzAd
, respectively. Sequence analysis showed that the components of NBDO have a high level of homology with the naphthalene family of Rieske nonheme iron oxygenases, in particular, 2-nitrotoluene dioxygenase from
Pseudomonas
sp. strain JS42. The enzyme oxidizes a wide range of substrates, and relative reaction rates with partially purified Oxygenase
NBZ
revealed a preference for 3-nitrotoluene, which was shown to be a growth substrate for JS765. NBDO is the first member of the naphthalene family of Rieske nonheme iron oxygenases reported to oxidize all of the isomers of mono- and dinitrotoluenes with the concomitant release of nitrite.
摘要
Comamonas
菌株 JS765 能以硝基苯作为唯一的碳、氮和能量来源进行生长。我们在此报告了编码硝基苯二氧酶(NBDO)的基因序列,该酶催化了 JS765 菌株降解硝基苯的第一步。NBDO 的组分被命名为还原酶
NBZ
铁氧化还原酶
NBZ
氧化酶
NBZα
和氧化酶
NBZβ
,基因名称为
nbzAa
,
nbzAb
,
nbzAc
和
nbzAd
和 nbzAd。序列分析表明,NBDO 的组成成分与萘家族的里斯克非血红素铁氧合酶,特别是假单胞菌中的 2-硝基甲苯二氧合酶,具有高度的同源性。
假单胞菌
菌株 JS42 的 2-硝基甲苯二氧酶。该酶可氧化多种底物,与部分纯化的加氧酶的相对反应速率如下
NBZ
的相对反应速率显示,该酶偏好 3-硝基甲苯,而 3-硝基甲苯被证明是 JS765 的生长底物。据报道,NBDO 是萘系里斯克非血红素铁氧合酶家族的第一个成员,它能氧化一硝基甲苯和二硝基甲苯的所有异构体,同时释放亚硝酸盐。