Max-Planck-Institut für Biophysik, Frankfurt am Main, Germany.
Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe-Universität Frankfurt am Main, Germany.
FEBS Lett. 2018 Feb;592(3):332-342. doi: 10.1002/1873-3468.12971. Epub 2018 Feb 1.
Flavin-based electron bifurcation (FBEB) is a recently discovered mode of energy coupling in anaerobic microorganisms. The electron-bifurcating caffeyl-CoA reductase (CarCDE) catalyzes the reduction of caffeyl-CoA and ferredoxin by oxidizing NADH. The 3.5 Å structure of the heterododecameric Car(CDE) complex of Acetobacterium woodii, presented here, reveals compared to other electron-transferring flavoprotein/acyl dehydrogenase family members an additional ferredoxin-like domain with two [4Fe-4S] clusters N-terminally fused to CarE. It might serve, in vivo, as specific adaptor for the physiological electron acceptor. Kinetic analysis of a CarCDE(∆Fd) complex indicates the bypassing of the ferredoxin-like domain by artificial electron acceptors. Site-directed mutagenesis studies substantiated the crucial role of the C-terminal arm of CarD and of ArgE203, hydrogen-bonded to the bifurcating FAD, for FBEB.
黄素依赖型电子分岔（FBEB）是一种在厌氧微生物中发现的新型能量偶联方式。电子分岔咖啡酰辅酶 A 还原酶（CarCDE）通过氧化 NADH 催化咖啡酰辅酶 A 和铁氧还蛋白的还原。这里呈现的，来自伍德氏醋酸杆菌的 Car(CDE)杂十二聚体的 3.5Å 结构，与其他电子传递黄素蛋白/酰基脱氢酶家族成员相比，CarE 氨基端融合了一个具有两个 [4Fe-4S] 簇的额外铁氧还蛋白样结构域。它可能在体内作为生理电子受体的特异性衔接子。对 CarCDE(∆Fd)复合物的动力学分析表明，人工电子受体可以绕过铁氧还蛋白样结构域。定点突变研究证实了 CarD 的 C 末端臂和 ArgE203 的关键作用，ArgE203 与分叉的 FAD 形成氢键，对 FBEB 至关重要。
