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首页> 外文期刊>Journal of bacteriology >A Second [2Fe-2S] Ferredoxin from Sphingomonas sp. Strain RW1 Can Function as an Electron Donor for the Dioxin Dioxygenase
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A Second [2Fe-2S] Ferredoxin from Sphingomonas sp. Strain RW1 Can Function as an Electron Donor for the Dioxin Dioxygenase

机译:鞘氨醇单胞菌属的第二种[2Fe-2S]铁氧还蛋白。菌株RW1可以作为二恶英双加氧酶的电子供体

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摘要

The first step in the degradation of dibenzofuran and dibenzo-p-dioxin by Sphingomonas sp. strain RW1 is carried out by dioxin dioxygenase (DxnA1A2), a ring-dihydroxylating enzyme. An open reading frame (fdx3) that could potentially specify a new ferredoxin has been identified downstream ofdxnA1A2, a two-cistron gene (J. Armengaud, B. Happe, and K. N. Timmis, J. Bacteriol. 180:3954–3966, 1998). In the present study, we report a biochemical analysis of Fdx3 produced inEscherichia coli. This third ferredoxin thus far identified in Sphingomonas sp. strain RW1 contained a putidaredoxin-type [2Fe-2S] cluster which was characterized by UV-visible absorption spectrophotometry and electron paramagnetic resonance spectroscopy. The midpoint redox potential of this ferredoxin (E′0 = ?247 ± 10 mV versus normal hydrogen electrode at pH 8.0) is similar to that exhibited by Fdx1 (?245 mV), a homologous ferredoxin previously characterized inSphingomonas sp. strain RW1. In in vitro assays, Fdx3 can be reduced by RedA2 (a reductase similar to class I cytochrome P-450 reductases), previously isolated from Sphingomonas sp. strain RW1. RedA2 exhibits a Km value of 3.2 ± 0.3 μM for Fdx3. In vivo coexpression of fdx3and redA2 with dxnA1A2 confirmed that Fdx3 can serve as an electron donor for the dioxin dioxygenase.
机译:鞘氨醇单胞菌属 sp降解二苯并呋喃和二苯并- p -二恶英的第一步。 RW1菌株是由环二羟基化酶二恶英双加氧酶(DxnA1A2)进行的。在两个顺反子基因(d.dxnA1A2 )的下游发现了一个可能识别新铁氧还蛋白的开放阅读框( fdx3 )(J. Armengaud,B.Happe和KN Timmis,J. Bacteriol。180:3954-3966,1998)。在本研究中,我们报告了大肠杆菌中产生的Fdx3的生化分析。迄今为止,在鞘氨醇单胞菌 sp中鉴定出了第三种铁氧还蛋白。菌株RW1含有一个Putodaredoxin型[2Fe-2S]团簇,其特征在于紫外可见吸收分光光度法和电子顺磁共振波谱。该铁氧还蛋白的中点氧化还原电位(E'sub> 0 = 247±10 mV,相对于pH 8.0的正常氢电极)类似于以前表征的同源铁氧还蛋白Fdx1的中点氧化还原电位(?245 mV)。 in 鞘氨醇单胞菌 sp。菌株RW1。在体外测定中,Fdx3可以被RedA2还原(一种类似于I类细胞色素P-450还原酶的还原酶),该酶以前是从 Sphingomonas sp。中分离出来的。菌株RW1。 RedA2对Fdx3的 K m 值为3.2±0.3μM。 fdx3 redA2 dxnA1A2 的体内共表达证实Fdx3可以作为二恶英双加氧酶的电子供体。

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