Trichloroethene reductive dehalogenase from Dehalococcoides ethenogenes:: Sequence of tceA and substrate range characterization
Trichloroethene reductive dehalogenase from Dehalococcoides ethenogenes:: Sequence of tceA and substrate range characterization
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DOI：
10.1128/aem.66.12.5141-5147.2000
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发表时间：
2000-12-01
影响因子：
4.4
通讯作者：
Kingsley, MT
中科院分区：
文献类型：
--
作者：
Magnuson, JK;Romine, MF;Kingsley, MT
厌氧细菌 Dehalococcoides ethenogenes 是唯一已知的能够通过脱卤呼吸将四氯乙烯或三氯乙烯 (TCE) 完全脱氯为乙烯的生物。 TCE 还原脱卤酶 (TCE-RDase) 是负责该途径的两种含类咕啉酶之一，可催化 TCE 脱氯生成乙烯。 TCE-RDase 将 1,2-二氯乙烷和 1,2-二溴乙烷脱卤生成乙烯，速率分别为 7.5 和 30 μmol/min/mg，与 TCE、顺式二氯乙烯 (DCE) 和 1,1-DCE 的速率相似。含有三到五个碳原子的各种其他卤代烷和卤代烯烃以较低的速率脱卤。通过反向 PCR 方法克隆并测序了编码 TCE-RDase 的基因 tceA。 tceA 与公共数据库中蛋白质的序列比较显示，序列相似性较弱，仅限于 C 末端区域，该区域包含八铁铁氧还蛋白簇结合基序 (CXXCXXCXXXCP)(2)。成熟酶的直接 N 端测序表明前 42 个氨基酸构成包含双精氨酸基序 RRXFXK 的信号序列，与 Sec 独立的膜易位系统相关。该信息与膜定位研究相结合表明 TCE-RDase 位于细胞质膜的外部。与已克隆和测序的其他两种 RDase 的情况一样，一个小的开放阅读框 tceB 被认为与 TCE-RDase 的膜关联有关，并预计与 tceA 共转录。
The anaerobic bacterium Dehalococcoides ethenogenes is the only known organism that can completely dechlorinate tetrachloroethene or trichloroethene (TCE) to ethene via dehalorespiration. One of two corrinoid-containing enzymes responsible for this pathway, TCE reductive dehalogenase (TCE-RDase) catalyzes the dechlorination of TCE to ethene. TCE-RDase dehalogenated 1,2-dichloroethane and 1,2-dibromoethane to ethene at rates of 7.5 and 30 mu mol/min/mg, respectively, similar to the rates for TCE, cis-dichloroethene (DCE), and 1,1-DCE. A variety of other haloalkanes and haloalkenes containing three to five carbon atoms were dehalogenated at lower rates. The gene encoding TCE-RDase, tceA, was cloned and sequenced via an inverse PCR approach. Sequence comparisons of tceA to proteins in the public databases revealed weak sequence similarity confined to the C-terminal region, which contains the eight-iron ferredoxin cluster binding motif, (CXXCXXCXXXCP)(2). Direct N-terminal sequencing of the mature enzyme indicated that the first 42 amino acids constitute a signal sequence containing the twin-arginine motif, RRXFXK, associated with the Sec-independent membrane translocation system. This information coupled with membrane localization studies indicated that TCE-RDase is located on the exterior of the cytoplasmic membrane. Like the case for the two other RDases that have been cloned and sequenced, a small open reading frame, tceB, is proposed to be involved with membrane association of TCE-RDase and is predicted to be cotranscribed with tceA.