Resting mitochondrial complex I from Drosophila melanogaster adopts a helix-locked state.
Resting mitochondrial complex I from Drosophila melanogaster adopts a helix-locked state.
复制标题
DOI：
10.7554/elife.84415
复制
发表时间：
2023-03-23
期刊：
影响因子：
7.7
通讯作者：
Letts JA
中科院分区：
文献类型：
--
作者：
Padavannil A;Murari A;Rhooms SK;Owusu-Ansah E;Letts JA
呼吸复合体I是一种质子泵送氧化还原酶，是生物能量代谢的关键。生物化学研究发现，在后生动物中，复合体I的行为存在差异，这与原造口动物和后造口动物之间的进化分裂一致。来自后口动物（包括哺乳动物）的复合体I可以采用生物化学定义的非通路“失活”状态，而来自原口动物的复合体I则不能。通路外状态的存在使结构结果的解释复杂化，并导致了相当大的机制辩论。在这里，我们报告了线粒体复合体I的结构，从模型原始动物黑腹果蝇的胸肌。我们发现，虽然黑腹菌复合体I （Dm-CI）不具有nem敏感的失活状态，但它确实表现出缓慢的激活动力学，表明其处于非通路静息状态。胸肌Dm-CI静息态结构显示多种构象。我们发现了一种螺旋锁定状态，在这种状态下，NDUFS4亚基上的n端α-螺旋楔入外周和膜臂之间。将Dm-CI结构和构象状态与在细菌、酵母和哺乳动物中观察到的结构和构象状态进行比较，可以深入了解亚基在生物体中的作用，解释为什么Dm-CI的非通路静息状态对NEM不敏感，并提出有关当前复合物I转换机制模型的问题。
Respiratory complex I is a proton-pumping oxidoreductase key to bioenergetic metabolism. Biochemical studies have found a divide in the behavior of complex I in metazoans that aligns with the evolutionary split between Protostomia and Deuterostomia. Complex I from Deuterostomia including mammals can adopt a biochemically defined off-pathway ‘deactive’ state, whereas complex I from Protostomia cannot. The presence of off-pathway states complicates the interpretation of structural results and has led to considerable mechanistic debate. Here, we report the structure of mitochondrial complex I from the thoracic muscles of the model protostome Drosophila melanogaster. We show that although D. melanogaster complex I (Dm-CI) does not have a NEM-sensitive deactive state, it does show slow activation kinetics indicative of an off-pathway resting state. The resting-state structure of Dm-CI from the thoracic muscle reveals multiple conformations. We identify a helix-locked state in which an N-terminal α-helix on the NDUFS4 subunit wedges between the peripheral and membrane arms. Comparison of the Dm-CI structure and conformational states to those observed in bacteria, yeast, and mammals provides insight into the roles of subunits across organisms, explains why the Dm-CI off-pathway resting state is NEM insensitive, and raises questions regarding current mechanistic models of complex I turnover.