Chromosome Movement in Meiosis and Mitosis

描述(申请人提供)：该项目的长期目标是确定和描述减数分裂和有丝分裂过程中染色体运动背后的力量，包括染色体与纺锤体和纺锤体组装和功能所涉及的微管动力学的相互作用。一个主要的目标是了解微管马达蛋白在细胞分裂过程中在纺锤体和染色体动力学中的作用，包括马达方向性和力产生的分子基础，以及这些马达特性在分裂中的重要性。拟开展的研究主要集中在果蝇微管运动蛋白NCD。NCD马达在减数分裂和有丝分裂中对纺锤体的组装和功能起着至关重要的作用。这里提出的研究是为了检查基本的电机特性，目的是了解电机在细胞中是如何工作的。 拟议研究的具体目标是 1.确定电机方向性的结构基础。将确定NCD电机经历电机方向性所需的构象或角度变化的区域。2.确定对功能至关重要的马达的结构变化。对去偶联马达功能或改变核苷酸水解循环的突变体进行分析，以获得新马达构象的晶体结构，并提供有关马达机制的信息。 3.确定活细胞运动功能所必需的因素。一个在体外将马达转化为双向马达的突变体将在活细胞中进行分析，以检验运动方向性对纺锤体中NCD功能至关重要的假设。 这些研究涉及纺锤体中力产生的分子基础，以及微管马达在细胞分裂期间染色体运动中的作用。染色体分布缺陷会导致非整倍体和其他遗传异常，并与人类的肿瘤发生有关。

DESCRIPTION (provided by applicant): The long-term objectives of this project are to identify and characterize the forces that underlie chromosome movement in meiosis and mitosis, including interactions of the chromosomes with the spindle and microtubule dynamics involved in spindle assembly and function. A major goal is to understand the role of microtubule motor proteins in spindle and chromosome dynamics during cell division, including the molecular basis of motor directionality and force generation, and the importance of these motor properties in division. The proposed studies focus on Ncd, a minus-end kinesin microtubule motor protein of Drosophila. The Ncd motor plays an essential role in spindle assembly and function in meiosis and mitosis. The studies proposed here are to examine basic motor properties with the objective of understanding how motors work in the cell. The specific aims of the proposed studies are to 1. Determine the structural basis of motor directionality. The region of the Ncd motor that undergoes a conformational or angle change required for motor directionality will be determined. 2. Identify structural changes of the motor essential for function. Mutants that decouple motor functions or alter the nucleotide hydrolysis cycle will be analyzed to obtain crystal structures of new motor conformations and provide information about the motor mechanism. 3. Define factors essential for motor function in live cells. A mutant that converts the motor into a bidirectional motor in vitro will be analyzed in live cells to examine the hypothesis that motor directionality is essential to Ncd function in the spindle. These studies address the molecular basis of force generation in the spindle and the role of microtubule motors in chromosome movement during cell division. Defective chromosome distribution causes aneuploidy and other genetic abnormalities, and is associated with oncogenesis in humans.