RUI: Function and Structure of Dynein-2 in Tetrahymena thermophila

分子马达是自然界的纳米机器，蛋白质能有效地将化学能转化为机械运动。在这三种特征明确的运动蛋白中，肌凝蛋白和运动蛋白具有相同的运动基本设计，但运动蛋白的工作方式似乎与其他两种运动蛋白完全不同。动力蛋白本身在进化谱系中表现出相当大的多样性。这种多样性在具有纤毛或鞭毛的生物体中很明显，它们表达14-15种不同的动力蛋白重链异构体。由于这些同工异构体在参与运动活动的部分结构上彼此不同，因此预计每个同工异构体产生一个特定的运动范围。本项目的重点是Dyh2，由纤毛原生生物四膜虫产生的动力蛋白同工型之一。尽管目前对Dyh2的描述还不充分，但由于它涉及的几个任务，它特别令人感兴趣。本项目采用显微、遗传学和生物化学相结合的方法来获得有关Dyh2分子结构及其在细胞运动和细胞组织中的作用的新信息。四膜虫特别适合作为实验系统，因为它在一个简单的、基因可接近的单细胞中具有“高等”生物（包括哺乳动物）的细胞生物学复杂性。重要的是，任何四膜虫基因都可以很容易地通过同源替换进行修饰，这在高等真核生物中是不寻常的。除了提供关于动力蛋白运动蛋白的组织及其在细胞中的作用的新信息外，该项目还将吸引大量从事生物学研究的本科生。参与该项目的哈维马德学院的学生在工程和物理科学方面有很强的背景。生物学现在为物理科学家和工程师提供了许多引人注目的未来问题，例如，分子纳米机器的生物工程和生物物理学。这个项目为学生提供了一个有意义的研究经验，向他们介绍了生物系统的复杂性。

Molecular motors are nature's nanomachines, proteins that efficiently transduce chemical energy into mechanical movement. Among the three well-characterized motor proteins, myosin and kinesin share the same basic design for movement, but dynein appears to work in a fundamentally different way from the other two motor proteins. Dynein proteins themselves show considerable diversity across the evolutionary spectrum. This diversity is readily apparent in organisms with cilia or flagella, which express 14-15 different dynein heavy chain isoforms. Because the isoforms differ from one another in the parts of their structures involved in motor activity, it is expected that each isoform generates a specific range of movement. The focus of this project is Dyh2, one of the dynein isoforms produced by the ciliated protist Tetrahymena. Although poorly characterized at present, Dyh2 is particularly intriguing because of the several tasks in which it is implicated. This project uses a combination of microscopy, genetics and biochemistry to gain new information about the molecular structure of Dyh2 and its roles in cell motility and cell organization. Tetrahymena is particularly well-suited as an experimental system because it possesses the cell biological complexity of "higher" organisms (including mammals) in a simple, genetically-accessible single cell. Importantly, any Tetrahymena gene can be readily modified by homologous replacement, a feature that is unusual among higher eukaryotes. In addition to providing new information about the organization of dynein motor proteins and their roles in cells, this project will engage significant numbers of undergraduate students in biological research. The students at Harvey Mudd College participating in the project have strong backgrounds in engineering and the physical sciences. Biology now offers many compelling future problems for physical scientists and engineers, e.g., bioengineering and biophysics of molecular nanomachines. This project provides students with a meaningful research experience that introduces them to the complexity of biological systems.