Nascent SOD1 in Amyotrophic Lateral Sclerosis

人类铜锌超氧化物歧化酶（SOD 1）的突变导致一种遗传性的致命性 神经变性疾病肌萎缩侧索硬化症（ALS，Lou Gehrig病，运动神经元病）。 随着年龄的增长，突变SOD 1的不溶性形式在人的神经组织中逐渐积累， 在ALS患者和表达这些多肽的转基因小鼠的脊髓中，表明SOD 1- 连锁ALS是一种蛋白质错误折叠和聚集障碍。了解分子基础， 致病性突变产生易于聚集的SOD 1折叠中间体，因此， 强烈的兴趣。当新生的SOD 1多肽被降解时，折叠途径上的关键步骤发生。 由SOD 1（CCS）的铜分子伴侣进行后修饰，这是一种插入 催化铜辅因子并氧化SOD 1亚基内二硫键。CCS识别并绑定到 新生的，但不是成熟的SOD 1，这表明新的翻译形式存在于构象不同， 成熟的形式。最近的研究表明，来自分离自大肠杆菌的聚集体的致病性SOD 1蛋白， 培养的细胞和来自转基因小鼠的脊髓的细胞往往是金属缺陷的和/或缺乏 二硫键这些观察结果表明，致病突变可能会增强 通过阻碍CCS介导的SOD 1成熟来降低SOD 1折叠中间体的水平。概述的实验 在这个项目中，旨在探索新生SOD 1的结构和动力学，并检查其 与CCS的互动成功完成本文所载的目标将解决以下问题： 1)CCS识别新生SOD 1的结构决定因素是什么？（二） 功能性SOD 1/CCS复合物是异二聚体、异四聚体还是其他更高级的寡聚体？第三章 新生的SOD 1/CCS复合物在三维空间中的结构细节是什么？4)哪些因素 在没有CCS的情况下，如何控制新生和成熟SOD 1构象的相互转化？5)如何 ALS突变是否影响新生和成熟构象的相互转换？回答这些 这些问题是设计旨在抑制致病性SOD 1聚集的治疗剂的先决条件 在ALS中。 1

Mutations in human copper-zinc superoxide dismutase (SOD1) cause an inherited form of the fatal neurodegenerative disease amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease, motor neuron disease). With increasing age, insoluble forms of mutant SOD1 progressively accumulate in neural tissues of human ALS patients and in spinal cords of transgenic mice expressing these polypeptides, suggesting that SOD1- linked ALS is a protein misfolding and aggregation disorder. Understanding the molecular basis for how the pathogenic mutations give rise to SOD1 folding intermediates that are prone to aggregation is therefore of keen interest. A critical step on the folding pathway occurs when the nascent SOD1 polypeptide is posttranslationally modified by the copper chaperone for SOD1 (CCS), a helper protein that inserts the catalytic copper cofactor and oxidizes the SOD1 intrasubunit disulfide bond. CCS recognizes and binds to nascent, but not mature SOD1, suggesting that the newly translated form exists in a conformation distinct from the mature form. Recent studies reveal that pathogenic SOD1 proteins coming from aggregates isolated from cultured cells and from the spinal cords of transgenic mice tend to be metal-deficient and/or lacking the disulfide bond. These observations suggest the hypothesis that the disease-causing mutations may enhance levels of SOD1 folding intermediates by hindering CCS-mediated SOD1 maturation. The experiments outlined in this project are designed to probe the structure and dynamics of nascent SOD1 and to examine its interaction with CCS. Successful completion of the Aims contained herein will address the following questions: 1) What are the structural determinants that are responsible for the recognition of nascent SOD1 by CCS? 2) Is the functional SOD1/CCS complex heterodimeric, heterotetrameric, or some other higher order oligomer? 3) What are the structural details of the nascent SOD1/CCS complex in three dimensions? 4) What factors govern the interconversion of the nascent and mature SOD1 conformations in the absence of CCS? 5) How do the ALS mutations affect the interconversion of the nascent and mature conformations? Answers to these questions are prerequisites for the design of therapeutic agents aimed inhibiting pathogenic SOD1 aggregation in ALS. 1