Structural Biology of Mitochondrial Fission

描述（由申请人提供）：线粒体分裂是线粒体分裂的过程，对细胞活力至关重要，但在分子水平上知之甚少。线粒体分裂率在细胞凋亡过程中增加，随着细胞老化而降低；抑制人类裂变蛋白也能抑制细胞凋亡。因此，对线粒体分裂蛋白及其功能细节的精确了解将为控制与心脏病、癌症和艾滋病有关的细胞凋亡提供明确的策略。本研究的长期目标是确定线粒体分裂的机制及其在细胞凋亡中的作用。其他研究者的遗传学和细胞学研究表明，出芽酵母的线粒体分裂与Fis1、Mdv1和Dnm1蛋白有关。拟议的研究通过确定这些过程的生化和结构基础采取了不同的方法。指导性假设是，Fis1招募Mdv1和Dnm1来改变膜结构，这是它们在裂变和凋亡中所起作用的一部分。作为验证这一假设的第一步，最近确定了Fis1的高分辨率结构。结合其他研究对该结构的分析提出了以下假设：1)Fis1蛋白具有两种不同的构象，每种构象都具有生物学意义；2)Fis1分子上由进化上保守的氨基酸组成的表面负责与自身和其他裂变蛋白结合；3)进入该结合表面的调控是细胞凋亡和裂变的重要调控机制。拟议的研究将通过多学科的方法来测试这些假设，包括体外测定蛋白质-蛋白质和蛋白质-膜相互作用；通过电子显微镜、核磁共振光谱和x射线晶体学进行结构研究；以及线粒体分裂和细胞死亡的体内试验。为了验证提出的假设，线粒体分裂和细胞凋亡的机制和调控将被确定。由于存在裂变蛋白的人类同源物，这项研究也将是设计抑制或诱导细胞凋亡新方法的第一步。

DESCRIPTION (provided by applicant): Mitochondrial fission, the process by which mitochondria divide, is essential for cell viability but poorly understood at a molecular level. The rate of mitochondrial fission increases during apoptosis and decreases as cells age; inhibition of a human fission protein also inhibits apoptosis. Therefore, a precise knowledge of the mitochondrial fission proteins and the details of their function will provide clear strategies to control apoptosis, which is linked to heart disease, cancer, and AIDS. The long-term goal of this research is to determine the mechanism of mitochondrial fission and its role in apoptosis. Genetic and cytological studies by other investigators have implicated the proteins Fis1, Mdv1, and Dnm1 in mitochondrial fission of budding yeast. The proposed research takes a different approach by determining the biochemical and structural basis for these processes. The guiding hypothesis is that Fis1 recruits Mdv1 and Dnm1 to alter membrane structure as part of their role in fission and apoptosis. As a first step towards testing this hypothesis, a high-resolution structure of Fis1 has recently been determined. The analysis of this structure in context of other studies suggests the following hypotheses: 1) that the Fis1 protein adopts two different conformations, each of which is biologically relevant, 2) that a surface on the Fis1 molecule comprised of evolutionarily conserved amino acids is responsible for binding to itself and other fission proteins, and 3) that regulation of access to this binding surface is an important regulatory mechanism in apoptosis and fission. The proposed research will test these hypotheses by a multi-disciplinary approach involving in vitro assays to determine protein-protein and protein-membrane interactions; structural studies by electron microscopy, NMR spectroscopy, and x-ray crystallography; and in vivo assays for mitochondrial fission and cell death. In validating the proposed hypotheses, the mechanisms and regulation of mitochondrial fission and cellular apoptosis will be identified. Since human homologues of the fission proteins exist, this research will also be a first step in designing new ways to inhibit or induce apoptosis.