Single-molecule studies of kinesin biophysics using DNA-kinesin chimeras

动蛋白是一类具有广泛功能的马达蛋白家族，包括分子货物在细胞内的运输，用于组织细胞内容物的刚性微管网络的组装和分解，以及细胞分裂时染色体的分离。传统的动蛋白有两个相同的头部，每个头部都可以结合到微管上。它手拉手地“行走”，这需要协调--重要的是，至少有一个头部始终保持绑定，否则马达很可能与其轨迹失去联系。马达协调头部并产生力量的机制仍不清楚。了解它们很重要，因为运动蛋白缺陷会导致疾病，而且在一些癌症治疗中，运动蛋白和微管是药物靶点。我们正在研究动蛋白的机制，方法是制造含有动蛋白元素的人造马达，这些马达连接到由短链DNA组装的框架上。这使我们能够改变共同工作的动蛋白头部的数量，或者它们之间联系的长度或弹性，这是单独使用天然蛋白质时不可能做到的。我们的目标是提高单个运动蛋白分子行走的测量精度，研究运动蛋白的头部是如何协调的，并研究有多少运动蛋白共同作用产生更大的力。

Kinesins are a family of motor proteins that have a wide range of functions including transport of molecular cargoes within cells, assembly and disassembly of networks of rigid microtubules that are used to organize cell contents, and the separation of chromosomes when cells divide. Conventional kinesin has two identical heads that can each bind to a microtubule. It 'walks' hand-over-hand, which requires coordination - it is important that at least one head remains bound at all times, otherwise the motor is likely to lose contact with its track. The mechanisms by which the motor coordinates its heads and generates force are still not clear. It is important to understand them, because defective kinesins can cause disease and because kinesin and microtubules are drug targets in some cancer therapies. We are studying the mechanism of kinesin by creating artificial motors incorporating elements of kinesin attached to frameworks assembled from short strands of DNA. This allows us to alter the number of kinesin heads that are working together, or the length or the elasticity of the link between them, in ways that are not possible when working with the natural protein alone. Our aims are to improve the precision of measurements of single kinesin molecules walking, to study how kinesin's heads are coordinated, and to investigate how many kinesins work together to create larger forces.