Defining Effects of Myosin VII Structure and Kinetics on Hereditary Deafness

描述（由申请人提供）：Myosin VII属于肌动蛋白激活的atp酶运动蛋白肌动蛋白家族，负责在真核生物的肌动蛋白细胞骨架上产生力。在哺乳动物中，肌球蛋白VII通常在极化细胞结构中表达，形成富含肌动蛋白的突起的有序阵列。基于突变生物体的表型和生化研究表明，肌凝蛋白VII处于与肌动蛋白紧密结合的状态，这种肌凝蛋白被认为主要作为锚点，维持这些结构中细胞骨架和膜组分之间的张力。肌球蛋白Vila的突变导致人类遗传性耳聋最常见的一种形式，但疾病表现的分子基础目前尚不清楚。尽管它在生物医学上具有重要意义，但目前还缺乏指示这种马达如何执行其细胞功能的结构和动力学细节。本提案的长期目标是了解肌球蛋白VII的酶和结构适应以及这些适应如何有助于精确的生物学功能。具体来说，本提案的第一个目的是确定在人类中产生耳聋表型的突变如何破坏肌球蛋白Vila的酶和运动特性。第二个目的是确定天然肌球蛋白VII的低聚状态，这是建立一个完整的肌球蛋白VII在细胞中的功能和运动模型所必需的。总的来说，本提案中描述的工作旨在建立一个更完整的肌球蛋白VII功能模型，并将为肌球蛋白VII功能障碍导致的耳聋的分子基础提供见解。与公共卫生的相关性：肌球蛋白Vila突变与Usher综合征Ib型（以及各种其他形式的遗传性耳聋）的发展直接相关，后者是人类遗传性耳聋-失明综合征的最大原因之一。目前对这些疾病患者缺乏治疗选择的一个根本原因是对耳和眼肌球蛋白VII功能的分子基础了解有限。拟议的研究重点是了解肌球蛋白VII如何作为一种分子运动功能，以更好地了解肌球蛋白VII运动活动的丧失如何导致耳聋。

DESCRIPTION (provided by applicant): Myosin VII belongs to the myosin family of actin-activated ATPase motor proteins responsible for generating force on the actin cytoskeleton in eukaryotes. In mammals, myosin VII is generally expressed in polarized cellular structures that form ordered arrays of actin-rich protrusions. Based on phenotypes of mutant organisms and biochemical studies demonstrating that myosin VII dwells in a state strongly-bound to actin, this myosin is thought to act primarily as an anchor by maintenance of tension between the cytoskeleton and membrane components in these structures. Mutations in myosin Vila results in one of the most common forms of inherited deafness in humans, but the molecular basis of disease presentation is currently unknown. Despite its biomedical importance, the structural and kinetic details that dictate how this motor performs its cellular functions are currently lacking. The long term goal of this proposal is to gain an understanding of the enzymatic and structural adaptations in myosin VII and how these contribute to precise biological function. Specifically, the first aim of this proposal is to identify how mutations that generate deafness phenotypes in humans disrupt the enzymatic and motor properties of myosin Vila. The second aim is to determine the oligomeric state of native myosin VII, which is necessary to develop a complete model of myosin VII function and motility in cells. As a whole, the work described in this proposal is directed towards the attainment of a more complete model for myosin VII function and will provide insight to the molecular basis of deafness that results from myosin VII dysfunction. Relevance to public health: Mutations in myosin Vila are directly associated with the development of Usher syndrome type Ib (and various other forms of inherited deafness), comprising one of the largest causes of inherited deafness-blindness syndromes in humans. A fundamental reason for the current lack of treatment options for patients with these diseases is a limited understanding of the molecular basis for myosin VII function in the ear and eye. The proposed research focuses on understanding how myosin VII functions as a molecular motor to better understand how loss of myosin VII motor activity leads to deafness.