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

Harvey Mudd College, Claremont CA

Investigators

Abstract

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.