Department of Structural Biology, Max-Planck-Institute of Biophysics, Frankfurt, Germany.
Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, Germany.
Nat Plants. 2023 Jan;9(1):142-156. doi: 10.1038/s41477-022-01308-6. Epub 2022 Dec 30.
Protein complexes of the mitochondrial respiratory chain assemble into respiratory supercomplexes. Here we present the high-resolution electron cryo-microscopy structure of the Arabidopsis respiratory supercomplex consisting of complex I and a complex III dimer, with a total of 68 protein subunits and numerous bound cofactors. A complex I-ferredoxin, subunit B14.7 and P9, a newly defined subunit of plant complex I, mediate supercomplex formation. The component complexes stabilize one another, enabling new detailed insights into their structure. We describe (1) an interrupted aqueous passage for proton translocation in the membrane arm of complex I; (2) a new coenzyme A within the carbonic anhydrase module of plant complex I defining a second catalytic centre; and (3) the water structure at the proton exit pathway of complex III with a co-purified ubiquinone in the Q site. We propose that the main role of the plant supercomplex is to stabilize its components in the membrane.
线粒体呼吸链的蛋白质复合物组装成呼吸超复合物。在这里，我们呈现了由复合物 I 和一个复合物 III 二聚体组成的拟南芥呼吸超复合物的高分辨率电子 cryo-microscopy 结构，总共有 68 个蛋白质亚基和许多结合的辅助因子。复合物 I-铁氧还蛋白、亚基 B14.7 和 P9，一种新定义的植物复合物 I 的亚基，介导超复合物的形成。组成复合物相互稳定，使我们能够对它们的结构有新的详细了解。我们描述了（1）在复合物 I 的膜臂中质子转移的中断的含水通道；（2）在植物复合物 I 的碳酸酐酶模块中的新辅酶 A 定义了第二个催化中心；以及（3）在复合物 III 的质子出口途径中的水结构，其中在 Q 位点有一个共纯化的 ubiquinone。我们提出，植物超复合物的主要作用是稳定其在膜中的组件。
