Role of Motor/cargo Attachment Mechanics in Collective Kinesin Transport

细胞的存活取决于蛋白质和化学物质进入不同功能区室的有效运输和分类。纳米级的运动蛋白可以抓住膜结合的货物，并沿着聚合物细丝移动它们，从而实现这种运输。由此产生的货物运动被认为是由多个运动蛋白的合作作用引起的，但合作的程度和使其成为可能的分子机制尚不清楚。一种可能的合作机制在于多个电机能够分担运输货物所需的负载。这种负载分配预计很大程度上取决于货物表面的机械性能，但负载分配、运输效率和货物力学之间的详细关系尚不清楚。本研究项目的目的是确定膜力学如何影响运动蛋白协同运输货物的能力。为此，将产生具有良好控制界面化学和力学性能的仿生货物，并在体外与运动蛋白偶联。货物表面的机械性能将从具有固定电机附着点的纯刚性表面变化到由可以重新排列其位置的脂质制成的纯流体表面。流体货物被认为能更好地模仿活细胞中货物的特性，随着运动蛋白的移动，运动结合位点可以很容易地在货物表面移动。这些界面脂质重排对货物运动的影响将使用精确的生物物理工具进行评估。具体来说，电机在外力作用下协同移动流体和刚性货物的能力将被确定并进行定量比较。计算机模拟和分析理论将被开发来理解实验数据，并产生可测试的预测膜力学对细胞内货物运输的影响。如果成功，这项研究将为细胞内运输的基本机制和调控提供重要的新见解，同时在生物学，物理学和工程学的界面上创造外展和培训活动。特别是，社区学院和本科生将参与动手研究，这项工作将形成一名研究生的论文项目，该研究生将在实验，计算和分析理论方面发展专业知识。该项目的研究成果将被纳入UCSB和Santa Barbara Advanced School for Quantitative Biology的跨学科生物物理/生物力学课程，并将在出版物和会议上广泛传播。

Cell survival depends on the efficient transport and sorting of protein and chemical species into different functional compartments. Nanoscale motor proteins that grasp membrane-bound cargos and move them along polymer filaments enable this transport. The resultant cargo motion is thought to arise from the cooperative action of multiple motor proteins, but the extent of cooperation and the molecular mechanisms that enable it are poorly understood. One possible mechanism for cooperation lies in the ability of multiple motors to share the load necessary to move the cargo. Such load splitting is expected to depend strongly on the mechanical properties of the cargo surface, but the detailed relationship between load splitting, transport efficiency, and cargo mechanics is unknown. The objective of this research project is to determine how membrane mechanics influences the ability of motor proteins to cooperatively transport cargos. To this end, biomimetic cargos with well-controlled interfacial chemistry and mechanical properties will be generated and coupled to motor proteins in vitro. The mechanical properties of the cargo surfaces will be varied from purely rigid surfaces with immobile motor attachment sites to purely fluid surfaces made of lipids that can rearrange their positions. The fluid cargos, which are thought to better mimic the properties of cargos in living cells, would allow motor binding sites to easily move on the cargo surface as the motor proteins move. The impact of these interfacial lipid rearrangements on cargo motion will be assessed using precision biophysical tools. Specifically, the ability of motors to cooperatively move fluid and rigid cargos against an external force will be determined and quantitatively compared. Computer simulations and analytical theory will be developed to understand the experimental data and generate testable predictions for the effects of membrane mechanics on cargo transport in cells. If successful, this research will provide important new insight into the fundamental mechanisms and regulation of intracellular transport, while creating outreach and training activities at the interface of biology, physics, and engineering. In particular, community college and undergraduate students will participate in hands-on research, and this work will form the thesis project of one graduate student, who will develop expertise in experiments, computation and analytical theory. The outcomes of this project will be incorporated into interdisciplinary biophysics/biomechanics courses at UCSB and the Santa Barbara Advanced School for Quantitative Biology, and will be disseminated broadly in publications and conferences.