Chemistry and energy transduction in kinesin motor proteins

描述（由申请人提供）：真核动力蛋白利用细胞骨架作为道路，将各种细胞内货物运输到相对较远的距离。ATP与水反应产生ADP和无机磷酸盐是启动关键细胞功能的马达蛋白的中心和主要步骤，包括有丝分裂期间的染色体分离、基因复制、转录以及囊泡和细胞器的运输。这些纳米发动机都通过消耗这种能量并将化学中间体耦合到一系列构象变化来发挥作用，这些构象变化推动了净细胞运动。对于驱动蛋白，这种催化反应及其化学机械转导的缺陷与人类的癌症、发育错误、肌病和神经退行性疾病有关。虽然一个复杂的序列的中间状态在ATP水解和mechanotransduction的预测，只有一小部分的状态已被验证的直接结构观察。因此，目前原子级相互作用的经验证据不足以评估生物ATP水解及其伙伴能量转导中的化学步骤的完整范围。我们实验室的最新数据捕获了关键的催化中间体，解决了有关机制的现存问题，并为进一步的进展提供了新的框架。基于这些发现，我们的主要目标是确定质子转移和氢键合的ATP水解和化学机械耦合在人类驱动蛋白-5蛋白，有丝分裂和癌症治疗的目标是必不可少的新的作用。要测试的问题是在ATP水解的第一步中的化学玩家的身份，环侧翼的活性位点是否经历构象变化的酶的过渡状态，如果中央2-片层有一个角色，从活性位点的信息转导到其他网站。预期答案的意义是双重的。由于化学和运动是同义反复联系在一起的，因此需要这些信息来阐明纳米马达中运动的分子机制，目前这些缺陷尚不清楚。此外，获得的实验证据将允许针对人驱动蛋白-5的抗癌药物的合理设计。 公共卫生相关性：驱动蛋白马达是生物学中已知的最小的运动机器，人类有大约50种不同的驱动蛋白马达。了解获得能量来操作和移动的关键反应不仅可以控制个体细胞过程，还可以控制特定的细胞类型。从这一提议中获得的信息可能为人类综合征提供临床力量，如分裂的癌细胞，神经系统疾病和不育症。

DESCRIPTION (provided by applicant): Eukaryotic motor proteins utilize the cytoskeleton as roadways to transport a variety of intracellular cargo across relatively vast distances. The reaction of ATP with water to produce ADP and inorganic phosphate is the central and primary step in motor proteins that initiates critical cellular functions, including chromosome segregation during mitosis, gene replication, transcription, and transport of vesicles and organelles. These nanomotors all function by consuming this energy and coupling the chemical intermediates to a series of conformational changes that propel net celular motion. For kinesins, defects in this catalytic reaction and its chemo-mechanical transduction are linked to cancer, developmental errors, myopathies, and neurodegenerative conditions in humans. Although a complex sequence of intermediate states during ATP hydrolysis and mechanotransduction is predicted, only a small subset of states has been validated by direct structural observation. Thus, current empirical evidence of atomic-level interactions is not sufficient to assess the complete range of chemical steps in biological ATP hydrolysis and its partnered energy transduction. Recent data from our laboratories has captured key catalytic intermediates that resolve extant questions regarding mechanism and provide a new framework for further progress. Building upon these findings, our principal goal is to define novel roles for proton transfer and hydrogen bonding for ATP hydrolysis and chemo-mechanical coupling in the human Kinesin-5 protein, essential for mitosis and a target for cancer therapeutics. Questions to be tested are the identity of the chemical player in the first step of ATP hydrolysis, whether loops flanking the active site undergo conformational changes in the enzyme transition state, and if the central 2-sheet has a role in transducing information from the active site to other sites. The significance of the anticipated answers is twofold. As chemistry and motion are tautologically linked, this information is required to illuminate molecular mechanisms of motion in nanomotors, which are currently unclear from these deficits. Moreover, garnered experimental evidence will allow rational design of anti-cancer drugs directed against human Kinesin-5. PUBLIC HEALTH RELEVANCE: Kinesin motors are the smallest moving machines known in biology, and humans have approximately 50 different kinds of kinesin motors. Understanding the key reaction in obtaining energy to operate and move can lead to control of not only individual, cellular processes, but also specific cell types. The information garnered from this proposal may offer clinical power over human syndromes, such as dividing cancer cells, neurological disorders, and infertility.