Characterization of nucleotide-dependent structural rearrangements in atlastin

描述（由申请人提供）：遗传性痉挛性截瘫（HSP）是一组遗传性神经系统疾病，导致下肢进行性痉挛和无力。atlastin-1基因突变是该病的主要突变热点之一，占常染色体显性HSP病例（SPG 3A亚型）的约10%，并且占婴儿或儿童病例的大多数。这种蛋白质的缺陷会导致独特的神经元（在这种情况下是上运动神经元）的轴突变性，但其分子机制仍知之甚少。巨噬细胞蛋白-1属于大型G蛋白的发动蛋白超家族，其成员参与多种细胞功能，包括内吞作用、细胞器融合和分裂、胞质分裂和抗病毒活性。在细胞水平上，atlastin-1通过促进同型膜融合参与产生管状内质网（ER）网络。这些动力蛋白相关的G蛋白，催化生物膜的同型融合，包括这个家庭的一小部分，并没有广泛的结构-功能关系的特点。结构表征以及伴侣蛋白相互作用的研究将为研究atlastin-1缺陷如何以及为什么导致其致病作用提供关键见解。第一个目标将是沿着核苷酸水解循环的atlastin-1沿着的结构表征。这一目标还将包括HSP相关蛋白质突变体的结构测定，以揭示致病机制。第二个目标集中在使用生物化学和生物物理方法的atlastin-1突变体的功能特性。这些研究将补充晶体学分析。通过对野生型和突变型atlastin-1变体进行彻底的结构-功能分析，可以推导出疾病发病机制的分子机制，这可以为疾病预后和干预提供更好的手段。

DESCRIPTION (provided by applicant): Hereditary spastic paraplegia (HSP) is a group of inherited neurological disorders that cause progressive spasticity and weakness in the lower extremities. Mutations in the atlastin-1 gene, one of the major mutational hot spots in the disease, account for ~10% of autosomal dominant HSP cases (subtype SPG3A), and for the majority of cases in infants or children. Defects in this protein results in axonal degeneration in unique sets of neurons, in this case upper motor neurons, yet the molecular mechanism is poorly understood. Atlastin-1 belongs to the dynamin superfamily of large G-proteins, members of which participate in diverse cellular functions, including endocytosis, organelle fusion and fission, cytokinesis, and antiviral activity. On a cellular level, atlastin-1 is involved in generating the tubular endoplasmic reticulum (ER) network by facilitating homotypic membrane fusion. Those dynamin-related G proteins that catalyze homotypic fusion of biological membranes comprise a small minority of this family, and have not been characterized extensively in their structure-function relationship. Structural characterization as well as investigation of partner protein interactions will provide key insights into how and why defects in atlastin-1 result in its pathogenic effects. The first objective will be the structural characterization of atlastin-1 along the nucleotide hydrolysis cycle. This aim will also include the structure determination of HSP-associated mutant variants of the protein in order to reveal pathogenic mechanisms. The second aim focuses on a functional characterization of atlastin-1 mutants using biochemical and biophysical approaches. These studies will complement the crystallographic analyses. By conducting thorough structure-function analyses of wild-type and mutant atlastin-1 variants, a molecular mechanism for disease pathogenesis can be derived, which may provide better means with regard to disease prognosis and intervention.