Building Cellular Complexity: from Molecular Motors to Synthetic Cilia

分子马达是一种纳米级的机器，它将三磷酸腺苷水解产生的化学能转化为沿丝状轨道的机械运动。在过去的二十年里，实验的进步已经产生了单分子马达迈出纳米级台阶的显着图像。此外，最先进的技术还使利用光学陷阱拉动这种纳米机器成为可能，从而确定它们可以施加的最大力。综上所述，这些努力为推动分离的分子马达运动的生化机制提供了重要的见解。然而，在许多情况下，从骨骼肌的收缩到生物纤毛的自发跳动，马达并不是孤立地起作用的。取而代之的是，数以千计的马达协调它们的活动来产生大规模的分子运动。尽管它很重要，但人们对分子马达系综的新兴集体性质知之甚少。该项目的第一个目标是开发一种实验测试，可以量化一对排列的微管之间的收缩滑移力，这种力是由同时结合两个细丝并沿两个细丝移动的分子马达簇施加的。这样的结构基序在生物细胞中驱动着许多复杂的过程。利用这些信息，该项目将建立微管束，这些微管束被夹在它们的底部，由分子马达驱动。理论模型预测，这种结构将自发跳动，从而模拟生物纤毛的动态行为。实验工作将直接验证这一预测，并为控制生物纤毛跳动模式的机制提供洞察。在实验工作的同时，该项目还将致力于开发分子马达集体行为的计算机模拟模型；这些模型将弥合现有理论模型和实验数据之间的差距。更广泛的影响：研究和外联工作将通过相互强调可视化和显微镜而无缝结合。通过显微镜获得的动态生物结构的电影吸引了科学家和非科学家的想象力和兴趣。PIS将在马萨诸塞州阿克顿的发现博物馆组织外展活动，在该博物馆将提供光学显微镜和标本，使参观者能够窥视微观世界并直接可视化生物运动。专业人员还将通过教授为期一周的强化实践暑期课程来传播光学显微镜的实用知识。研究人员参与非常成功的科学Posse计划将进一步加强来自历史上代表性不足的群体的本科生和研究生的参与。

Molecular motors are nanoscale machines that convert chemical energy from ATP hydrolysis into mechanical movement along a filamentous track. Over the past two decades experimental advances have yielded remarkable images of single molecular motors taking nanometer-sized steps. Furthermore, state-of-the-art technology also makes it possible to pull on such nanomachines with optical traps thus determining the maximal force they can exert. Taken together these efforts have provided essential insight into biochemical mechanisms driving the motility of isolated molecular motors. However in many instances, ranging from contraction of a skeletal muscle to spontaneous beating of a biological cilium, motors do not act in isolation. Instead, thousands of motors coordinate their activity to produce large scale molecular motion. Despite its importance, little is known about the emergent collective properties of molecular motor ensembles. The first goal of this project is to develop an experimental assay that will quantify contractile sliding forces between a pair of aligned microtubules, exerted by molecular motor clusters that simultaneously bind and move along both filaments. Such structural motifs drive numerous complex processes in a biological cell. Using this information, the project will build microtubule bundles that are clamped at their base and driven by molecular motors. Theoretical models predict that such structures will spontaneous beat, thus mimicking the dynamical behavior of biological cilia. Experimental efforts will directly verify this prediction and provide insight into the mechanisms that control beating patterns of biological cilia. In parallel with experimental efforts, this project will also pursue development of computer simulation models for collective behavior of molecular motors; these will bridge the gap between existing theoretical models and experimental data. Broader Impacts: The research and outreach efforts will be seamlessly integrated through a mutual emphasis on visualization and microscopy. Movies of dynamical biological structures obtained via microscopy capture the imagination and interest of scientists and non-scientists alike. The PIs will organize outreach activities at The Discovery Museum in Acton, MA, in which optical microscopes and specimens will be available at the museum, allowing visitors to peer into the microscopic world and directly visualize biological motion. The PIs will also disseminate practical knowledge of optical microscopy by teaching an intensive hands-on one-week summer course. Investigator involvement with the highly successful science Posse program will further enhance undergraduate and graduate student involvement from historically underrepresented groups.