PDF(Pubmed)
Abstract：
Cardiolipin (CL) is a mitochondria-specific phospholipid that forms heterotypic interactions with membrane-shaping proteins and regulates the dynamic remodeling and function of mitochondria. However, the precise mechanisms through which CL influences mitochondrial morphology are not well understood. In this study, employing molecular dynamics (MD) simulations, we observed CL localize near the membrane-binding sites of the mitochondrial fusion protein Optic Atrophy 1 (OPA1). To validate these findings experimentally, we developed a bromine-labeled CL probe to enhance cryoEM contrast and characterize the structure of OPA1 assemblies bound to the CL-brominated lipid bilayers. Our images provide direct evidence of interactions between CL and two conserved motifs within the paddle domain (PD) of OPA1, which control membrane-shaping mechanisms. We further observed a decrease in membrane remodeling activity for OPA1 in lipid compositions with increasing concentrations of monolyso-cardiolipin (MLCL). Suggesting that the partial replacement of CL by MLCL accumulation, as observed in Barth syndrome-associated mutations of the tafazzin phospholipid transacylase, compromises the stability of protein-membrane interactions. Our analyses provide insights into how biological membranes regulate the mechanisms governing mitochondrial homeostasis.
摘要：
心磷脂（CL）是一种线粒体特异性磷脂，与膜形成蛋白形成异型相互作用，并调节线粒体的动态重塑和功能。然而,CL影响线粒体形态的确切机制尚不清楚。在这项研究中,采用分子动力学(MD)模拟，我们观察到CL位于线粒体融合蛋白视神经萎缩1（OPA1）的膜结合位点附近。为了通过实验验证这些发现，我们开发了溴标记的CL探针以增强冷冻EM对比度并表征与CL溴化脂质双层结合的OPA1组装体的结构。我们的图像提供了CL与OPA1的桨域（PD）内两个保守基序之间相互作用的直接证据，这些基序控制膜成形机制。我们进一步观察到，随着单氢心磷脂（MLCL）浓度的增加，脂质组合物中OPA1的膜重塑活性降低。建议用MLCL积累部分替代CL，如在他法津磷脂转酰酶的Barth综合征相关突变中观察到的，损害了蛋白质-膜相互作用的稳定性。我们的分析提供了有关生物膜如何调节线粒体稳态的机制的见解。
■这项研究揭示了CL如何调节OPA1的活性以及MLCL如何影响其控制线粒体功能的能力。
■这项研究揭示了CL如何调节OPA1的活性以及MLCL如何影响其控制线粒体功能的能力。
