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(N
BDO)的
基因序列,该酶催化了 JS765 菌株降解
硝基苯的第一步。N
BDO 的组分被命名为还原酶
N
BZ
铁氧化还原酶
N
BZ
氧化酶
N
BZα
和氧化酶
N
BZβ
,
基因名称为
n
BZAa
,
n
BZAb
,
n
BZAc
和
n
BZAd
和 n
BZAd。序列分析表明,N
BDO 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
N
BZ
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,N
BDO 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。