Departments of Anesthesiology, Physiology, New York University Grossman School of Medicine, New York, New York, USA; Departments of Cell Biology, Physiology, New York University Grossman School of Medicine, New York, New York, USA.
Departments of Anesthesiology, Physiology, New York University Grossman School of Medicine, New York, New York, USA.
J Biol Chem. 2023 Oct;299(10):105241. doi: 10.1016/j.jbc.2023.105241. Epub 2023 Sep 9.
Respiratory complexes and cardiolipins have exceptionally long lifetimes. The fact that they co-localize in mitochondrial cristae raises the question of whether their longevities have a common cause and whether the longevity of OXPHOS proteins is dependent on cardiolipin. To address these questions, we developed a method to measure side-by-side the half-lives of proteins and lipids in wild-type Drosophila and cardiolipin-deficient mutants. We fed adult flies with stable isotope-labeled precursors (CN-lysine or C-glucose) and determined the relative abundance of heavy isotopomers in protein and lipid species by mass spectrometry. To minimize the confounding effects of tissue regeneration, we restricted our analysis to the thorax, the bulk of which consists of post-mitotic flight muscles. Analysis of 680 protein and 45 lipid species showed that the subunits of respiratory complexes I-V and the carriers for phosphate and ADP/ATP were among the longest-lived proteins (average half-life of 48 ± 16 days) while the molecular species of cardiolipin were the longest-lived lipids (average half-life of 27 ± 6 days). The remarkable longevity of these crista residents was not shared by all mitochondrial proteins, especially not by those residing in the matrix and the inner boundary membrane. Ablation of cardiolipin synthase, which causes replacement of cardiolipin by phosphatidylglycerol, and ablation of tafazzin, which causes partial replacement of cardiolipin by monolyso-cardiolipin, decreased the lifetimes of the respiratory complexes. Ablation of tafazzin also decreased the lifetimes of the remaining cardiolipin species. These data suggest that an important function of cardiolipin in mitochondria is to protect respiratory complexes from degradation.
呼吸复合物和心磷脂的寿命异常长。它们在线粒体嵴中共定位，这就提出了一个问题，即它们的长寿命是否有共同的原因，以及氧化磷酸化蛋白的寿命是否依赖于心磷脂。为了解决这些问题，我们开发了一种方法，可同时测量野生型果蝇和心磷脂缺陷突变体中线粒体蛋白和脂质的半衰期。我们用稳定同位素标记的前体（CN-赖氨酸或 C-葡萄糖）喂养成年果蝇，并通过质谱法确定蛋白质和脂质物种中重同位素体的相对丰度。为了最大限度地减少组织再生的混杂影响，我们将分析仅限于胸部，胸部主要由有丝分裂后飞行肌肉组成。对 680 种蛋白质和 45 种脂质的分析表明，呼吸复合物 I-V 的亚基和磷酸及 ADP/ATP 的载体是寿命最长的蛋白质之一（平均半衰期为 48±16 天），而心磷脂的分子种类是寿命最长的脂质（平均半衰期为 27±6 天）。这些嵴居民的显著长寿并不仅限于所有线粒体蛋白，尤其是那些位于基质和内膜的蛋白。心磷脂合酶的缺失会导致心磷脂被磷脂酰甘油取代，以及 tafazzin 的缺失会导致心磷脂被单酰基心磷脂部分取代，这都会降低呼吸复合物的寿命。tafazzin 的缺失也降低了其余心磷脂种类的寿命。这些数据表明，心磷脂在线粒体中的一个重要功能是保护呼吸复合物免受降解。
