气候变化领域集成服务门户(CCPortal): Cryoelectron microscopy structure and mechanism of the membrane-associated electron-bifurcating flavoprotein Fix/EtfABCX

CCPortal

DOI	10.1073/pnas.2016978118
	Cryoelectron microscopy structure and mechanism of the membrane-associated electron-bifurcating flavoprotein Fix/EtfABCX
	Feng X.; Schut G.J.; Lipscomb G.L.; Li H.; Adams M.W.W.
发表日期	2021
ISSN	00278424
卷号	118 期号:2
英文摘要	The electron-transferring flavoprotein-menaquinone oxidoreductase ABCX (EtfABCX), also known as FixABCX for its role in nitrogen-fixing organisms, is a member of a family of electron-transferring flavoproteins that catalyze electron bifurcation. EtfABCX enables endergonic reduction of ferredoxin (E°′ ∼−450 mV) using NADH (E°′ −320 mV) as the electron donor by coupling this reaction to the exergonic reduction of menaquinone (E°′ −80 mV). Here we report the 2.9 Å structure of EtfABCX, a membrane-associated flavin-based electron bifurcation (FBEB) complex, from a thermophilic bacterium. EtfABCX forms a superdimer with two membrane-associated EtfCs at the dimer interface that contain two bound menaquinones. The structure reveals that, in contrast to previous predictions, the low-potential electrons bifurcated from EtfAB are most likely directly transferred to ferredoxin, while high-potential electrons reduce the quinone via two [4Fe-4S] clusters in EtfX. Surprisingly, EtfX shares remarkable structural similarity with mammalian [4Fe-4S] cluster-containing ETF ubiquinone oxidoreductase (ETF-QO), suggesting an unexpected evolutionary link between bifurcating and nonbifurcating systems. Based on this structure and spectroscopic studies of a closely related EtfABCX, we propose a detailed mechanism of the catalytic cycle and the accompanying structural changes in this membrane-associated FBEB system. © 2021 National Academy of Sciences. All rights reserved.
英文关键词	Electron bifurcation; Flavin; Iron-sulfur cluster; Menaquinone; Thermotoga
语种	英语
scopus关键词	electron transferring flavoprotein; electron transferring flavoprotein FixABCX; ETF ubiquinone oxidoreductase; ferredoxin; oxidoreductase; unclassified drug; Acidaminococcus fermentans; alpha helix; amino terminal sequence; Article; beta sheet; binding affinity; binding site; carboxy terminal sequence; conformational transition; controlled study; cryoelectron microscopy; dimerization; electron transport; energy metabolism; hydrogen bond; hydrophobicity; nonhuman; oxidation reduction state; priority journal; protein binding; protein conformation; protein expression; protein function; protein protein interaction; protein purification; protein stability; protein structure; Pyrococcus furiosus; thermophilic bacterium; Thermotoga maritima
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/181077
作者单位	Department of Structural Biology, Van Andel Institute, Grand Rapids, MI 49503, United States; Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, United States
推荐引用方式 GB/T 7714	Feng X.,Schut G.J.,Lipscomb G.L.,et al. Cryoelectron microscopy structure and mechanism of the membrane-associated electron-bifurcating flavoprotein Fix/EtfABCX[J],2021,118(2).
APA	Feng X.,Schut G.J.,Lipscomb G.L.,Li H.,&Adams M.W.W..(2021).Cryoelectron microscopy structure and mechanism of the membrane-associated electron-bifurcating flavoprotein Fix/EtfABCX.Proceedings of the National Academy of Sciences of the United States of America,118(2).
MLA	Feng X.,et al."Cryoelectron microscopy structure and mechanism of the membrane-associated electron-bifurcating flavoprotein Fix/EtfABCX".Proceedings of the National Academy of Sciences of the United States of America 118.2(2021).