Structural Biology of Mitochondrial Fission

描述(申请人提供)：线粒体分裂，线粒体分裂的过程，是细胞存活所必需的，但在分子水平上知之甚少。线粒体裂变率在细胞凋亡过程中增加，并随着细胞年龄的增长而降低；抑制人类分裂蛋白也会抑制细胞凋亡。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。这项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。其他研究人员的遗传学和细胞学研究表明，Fis1、Mdv1和DNM1蛋白与发芽酵母的线粒体分裂有关。拟议的研究采取了一种不同的方法，确定了这些过程的生化和结构基础。指导性假设是FIS1招募MDv1和DNM1来改变膜结构，作为它们在分裂和凋亡中作用的一部分。作为检验这一假说的第一步，最近已经确定了FIS1的高分辨率结构。在其他研究背景下对这种结构的分析提出了以下假设：1)FIS1蛋白采用两种不同的构象，每种构象都具有生物学意义；2)FIS1分子表面由进化上保守的氨基酸组成，负责与其自身和其他裂变蛋白结合；3)对该结合表面的调节是细胞凋亡和分裂中的重要调控机制。这项拟议的研究将通过一种多学科的方法来检验这些假设，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射线结晶学进行结构研究；以及体内线粒体分裂和细胞死亡的测定。在验证所提出的假说时，将确定线粒体分裂和细胞凋亡的机制和调控。由于人类存在裂变蛋白的同源物，这项研究也将是设计抑制或诱导细胞凋亡的新方法的第一步。

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.