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Direct Electron Transfer between the frhAGB-Encoding Hydrogenase and Thioredoxin Reductase in the Non-Methanogenic Archaeon Thermococcus onnurineus NA1
Applied and Environmental Microbiology ( IF 3.9 ) Pub Date : 2020-01-10
Jung, H.-C., Lim, J. K., Yang, T.-J., Kang, S. G., Lee, H. S.

To date, NAD(P)H, ferredoxin, and coenzyme F420 have been identified as electron donors for thioredoxin reductase (TrxR). In this study, we present a novel electron source for TrxR. In the hyperthermophilic archaeon Thermococcus onnurineus NA1, the frhAGB-encoding hydrogenase, a homolog of the F420-reducing hydrogenase of methanogens, was demonstrated to interact with TrxR in coimmunoprecipitation experiments and in vitro pull-down assays. Electrons derived from H2 oxidation by the frhAGB-encoding hydrogenase were transferred to TrxR and reduced Pdo, a redox partner of TrxR. Interaction and electron transfer were observed between TrxR and the heterodimeric hydrogenase complex (FrhAG) as well as the heterotrimeric complex (FrhAGB). Hydrogen-dependent reduction of TrxR was seven-fold less efficient than when NADPH was electron donor. This study not only presents a different type of electron donor for TrxR but also reveals new functionality of the frhAGB-encoding hydrogenase utilizing a protein as an electron acceptor.

IMPORTANCE This study has importance in that TrxR can use H2 as an electron donor with the aid of the frhAGB-encoding hydrogenase as well as NAD(P)H in T. onnurineus NA1. Further studies are needed to explore the physiological significance of this protein. This study also has importance as a significant step toward understanding the functionality of the frhAGB-encoding hydrogenase in a non-methanogen: the hydrogenase can transfer electrons derived from oxidation of H2 to a protein target by direct contact without the involvement of an electron carrier, which is distinct from the mechanism of its homologs, F420-reducing hydrogenases of methanogens.



中文翻译:

非甲烷化古生嗜热球菌NA1的frhAGB编码加氢酶和硫氧还蛋白还原酶之间的直接电子转移。

迄今为止,NAD(P)H,铁氧还蛋白和辅酶F 420已被确定为硫氧还蛋白还原酶(TrxR)的电子供体。在这项研究中,我们提出了TrxR的新型电子源。在超嗜热古生菌嗜热球菌NA1中,在共同免疫沉淀实验和体外下拉试验中,证明了frhAGB编码的氢酶(产甲烷酶的F 420还原性氢酶的同系物)与TrxR相互作用。frhAGB衍生自H 2氧化的电子-编码的加氢酶被转移到TrxR和还原的Pdo,Trdo的氧化还原伴侣。TrxR和异二聚体氢化酶复合物(FrhAG)以及异三聚体复合物(FrhAGB)之间观察到相互作用和电子转移。氢依赖的TrxR还原效率比NADPH为电子供体时低7倍。这项研究不仅为TrxR提供了不同类型的电子供体,而且还揭示了利用蛋白质作为电子受体的frhAGB编码加氢酶的新功能。

重要事项这项研究具有重要意义,因为TrxR可以利用frhAGB编码的氢酶以及T. onnurineus NA1中的NAD(P)H来利用H 2作为电子供体。需要进一步的研究来探索这种蛋白质的生理意义。这项研究对于理解非甲烷源中编码frhAGB的加氢酶的功能性迈出了重要的一步:加氢酶可以通过直接接触将H 2氧化衍生的电子转移至蛋白质靶标,而无需电子载体的参与与它的同系物F 420还原产甲烷酶的氢酶不同。

更新日期:2020-01-13
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