Bridging Understanding of Motor-Cargo Transport from Artificial to Cellular Systems

基于微管的转运对细胞功能至关重要。胞内货物的正确运输涉及到 在以不同速度和不同方向移动的马达蛋白和微管之间相互作用， 它可以定向为均匀或混合的极性束，也可以通过 翻译后修饰(PTM)和微管相关蛋白(MAP)。中的主导模式 描述双向运动的场是拔河模型，在该模型中，反向动蛋白和 动力素马达在短时间内机械地争夺支配地位和控制运动。然而，a 在过去的15年里，在分离的细胞和模型生物中进行的一些研究发现 抑制一种运动会削弱两个方向的运动性，这与拔河模型正好相反。 预测。这项提议的目的是利用数学建模和体外实验来 研究导致拉锯战模型的预测在细胞上达不到的机制 比例。缩小这一知识鸿沟需要实验和理论的综合发展 模型，以便将分子尺度上的基本机制与细胞内观察到的 运输行为。建模将跨越三个层次。纳米级建模将使用已建立的 肌动蛋白和动力蛋白步进动力学及运动微管变化的研究框架 微管蛋白PTMS和MAP结合所致的相互作用。在中尺度上，多个马达绑定到一个共同的 将货物表示为服从具有性能的随机微分模型的连续运动 从现有实验数据中提取的特征。最后，在微观层面上， 具有多个微管的车货复合体及其运输对微管的依赖 在细胞水平上的组织被治疗。 在目标1中，具有确定数量的动蛋白和动力蛋白的体外和电子实验将用于 挑战双向运输的特定假设模型。在目标2中，这一综合办法将是 扩展到了解在体外和硅胶中模拟细胞的微管结构中的运输动力学。

Microtubule-based transport is vital for cell function. Proper transport of intracellular cargo involves an interplay between motor proteins that move at different speeds and in different directions, and microtubules, which can be oriented in either uniform or mixed polarity bundles and can also be altered by posttranslational modifications (PTMs) and microtubule associated proteins (MAPs). The dominant model in the field to describe the bidirectional motion is the tug-of-war model in which opposite-directed kinesin and dynein motors mechanically compete for dominance and control movement for short durations. However, a number of studies carried out in isolated cells and model organisms over the last 15 years have found that inhibiting one motor diminishes motility in both directions, just the opposite of the tug-of-war model prediction. The purpose of this proposal is to use mathematical modeling and in vitro experiments to investigate the mechanisms that cause the predictions of the tug-o-war model to fall short at the cellular scale. Closing this knowledge gap requires the integrated development of experiments and theoretical models in order to link fundamental mechanisms at the molecular scale with the observed within-cell transport behavior. The modeling will span three levels. Nanoscale modeling will use established frameworks to treat the kinetics of kinesin and dynein stepping and changes in motor-microtubule interactions due to tubulin PTMs and MAP binding. At the mesoscale, multiple motors bound to a common cargo are represented as continuous movers obeying stochastic differential models with performance characteristics taken from existing experimental data. Finally, at the microscale, the interaction of motor-cargo complexes with multiple microtubules and the dependence of transport on microtubule organization at the cellular level are treated. In Aim 1, in vitro and in silico experiments with defined numbers of kinesins and dyneins will be used to challenge specific hypothetical models of bidirectional transport. In Aim 2, this integrated approach will be extended to understand transport dynamics in cell-mimicking microtubule architectures in vitro and in silico.