Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA.
Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
Nat Chem Biol. 2021 Jun;17(6):703-710. doi: 10.1038/s41589-021-00772-z. Epub 2021 Mar 15.
The protein complexes of the mitochondrial electron transport chain exist in isolation and in higher order assemblies termed supercomplexes (SCs) or respirasomes (SC I+III+IV). The association of complexes I, III and IV into the respirasome is regulated by unknown mechanisms. Here, we designed a nanoluciferase complementation reporter for complex III and IV proximity to determine in vivo respirasome levels. In a chemical screen, we found that inhibitors of the de novo pyrimidine synthesis enzyme dihydroorotate dehydrogenase (DHODH) potently increased respirasome assembly and activity. By-passing DHODH inhibition via uridine supplementation decreases SC assembly by altering mitochondrial phospholipid composition, specifically elevated peroxisomal-derived ether phospholipids. Cell growth rates upon DHODH inhibition depend on ether lipid synthesis and SC assembly. These data reveal that nucleotide pools signal to peroxisomes to modulate synthesis and transport of ether phospholipids to mitochondria for SC assembly, which are necessary for optimal cell growth in conditions of nucleotide limitation.
线粒体电子传递链的蛋白质复合物以孤立的形式存在，也存在更高阶的组装形式，称为超复合物（SCs）或呼吸体（SC I+III+IV）。复合物 I、III 和 IV 形成呼吸体的关联受未知机制调控。在这里，我们设计了一种用于复合物 III 和 IV 临近性的纳米荧光素酶互补报告器，以确定体内呼吸体水平。在化学筛选中，我们发现从头嘧啶合成酶二氢乳清酸脱氢酶（DHODH）的抑制剂可通过改变线粒体磷脂组成，特别是增加过氧化物酶体衍生的醚磷脂，强力增加呼吸体组装和活性。通过补充尿嘧啶绕过 DHODH 抑制，通过改变线粒体磷脂组成，特别是增加过氧化物酶体衍生的醚磷脂，改变线粒体磷脂组成，从而降低 SC 组装。DHODH 抑制后细胞生长速率取决于醚脂合成和 SC 组装。这些数据表明核苷酸池向过氧化物体发出信号，以调节醚磷脂的合成和运输到线粒体以进行 SC 组装，这对于在核苷酸限制条件下的最佳细胞生长是必需的。
