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首页> 外文期刊>The FEBS journal >Electron-transfer subunits of the NiFe hydrogenases in Thiocapsa roseopersicina BBS
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Electron-transfer subunits of the NiFe hydrogenases in Thiocapsa roseopersicina BBS

机译：玫瑰硫硫杆菌BBS中NiFe氢化酶的电子转移亚基

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摘要

Thiocapsa roseopersicina BBS contains at least three different active NiFe hydrogenases: two membrane-bound enzymes and one apparently localized in the cytoplasm. In addition to the small and large structural subunits, additional proteins are usually associated with the NiFe hydrogenases, connecting their activity to other redox processes in the cells. The operon of the membrane-associated hydrogenase, HynSL, has an unusual gene arrangement: between the genes coding for the large and small subunits, there are two open reading frames, namely isp1 and isp2. Isp1 is a b-type haem-containing transmembrane protein, whereas Isp2 displays marked sequence similarity to the heterodisulfide reductases. The other membrane-bound (Hup) NiFe hydrogenase contains the hupC gene, which codes for a cytochrome b-type protein that probably plays a role in electron transport. The operon of the NAD(+)-reducing Hox hydrogenase contains a hoxE gene. In addition to the hydrogenase and diaphorase parts of the complex, the fifth HoxE subunit may serve as a third redox gate of this enzyme. The physiological functions of these putative electron-mediating subunits were studied by disruption of their genes. The deletion of some accessory proteins dramatically reduced the in vivo activities of the hydrogenases, although they were fully active in vitro. The absence of HupC resulted in a decrease in HupSL activity in the membrane, but removal of the Isp1 and Isp2 proteins did not have any significant effect on the location of HynSL activity. Through the use of a tagged HoxE protein, the whole Hox hydrogenase pentamer could be purified as an intact complex.
机译：玫瑰色硫杆菌（Thiocapsa roseopersicina）BBS至少包含三种不同的活性NiFe氢化酶：两种膜结合酶，一种明显位于细胞质中。除大小结构亚基外，其他蛋白质通常与NiFe氢化酶相关，将其活性与细胞中的其他氧化还原过程联系起来。膜相关氢化酶的操纵子HynSL具有不寻常的基因排列：在编码大亚基和小亚基的基因之间，有两个开放阅读框，即isp1和isp2。 Isp1是一种b型含血红素的跨膜蛋白，而Isp2与异二硫键还原酶具有明显的序列相似性。另一个与膜结合的（Hup）NiFe氢化酶包含hupC基因，该基因编码可能在电子传输中起作用的细胞色素b型蛋白。减少NAD（+）的Hox氢化酶的操纵子包含hoxE基因。除了复合物的氢化酶和心肌黄递酶部分外，第五个HoxE亚基还可以充当该酶的第三个氧化还原门。这些推定的电子介导亚基的生理功能通过其基因的破坏进行了研究。尽管一些辅助蛋白在体外具有完全活性，但它们的缺失却大大降低了氢化酶的体内活性。没有HupC会导致膜中HupSL活性降低，但是Isp1和Isp2蛋白的去除对HynSL活性的位置没有任何显着影响。通过使用标记的HoxE蛋白，可以将完整的Hox加氢酶五聚体纯化为完整的复合物。

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