CAREER: Exploring the Functional Diversity of Cytoplasmic Dynein

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Cells are the building blocks of all organisms. All living cells must be able to reorganize their contents rapidly to function properly. To promote intracellular movements, motor proteins transport cellular material throughout the eukaryotic cell. Some motors move along tracks called microtubules that function as cellular highways. Nearly everything that must move around the cell is transported by motor proteins, from smaller proteins to organelles like mitochondria. If motor proteins’ functions are impaired, cells can die or malfunction. Remarkably, only one type of motor, called dynein, transports cargo towards the interior of the cell for long distances. As the only such motor, dynein must be able to bind and transport many different types of cellular cargo, even though each kind of cargo may need to move at different speeds, be vastly different in size, or move only at specific times. A second set of proteins, called adaptors, bind to dynein and enable it to transport different types of cargos. The goal of this proposal is to understand how different adaptor proteins enable dynein motors to move cargos of different sizes at different speeds at different times. The expected results will reveal how adaptor proteins alter the characteristics of dynein to display different motile properties. This research project will also train both undergraduate and graduate students in microscopy and biophysical techniques, and to communicating experimental findings to a broad public audience using non-traditional approaches such as dance and theater. A collaboration in conjunction with the University of Michigan’s Museum of Natural History will also develop hands-on, research-driven programs for middle and high-school-aged students to learn about fluorescence microscopy and motor proteins. The research of this project will address how a class of cellular proteins, called adaptors, enable dynein to traffic diverse cargoes. Preliminary work has revealed that individual adaptor proteins confer distinct motile properties to the mammalian dynein-1 motor. To build on this finding, the investigators will: 1) Determine why different adaptors have distinct effects on dynein motility; 2) Determine how each adaptor tunes the activity of teams of dynein motors; 3) Determine how each adaptor specifically modulates activation of the dynein motor. To accomplish these goals, the investigators will use single-molecule fluorescence imaging, protein biochemistry, complex in vitro reconstitutions to generate teams of motors on a native-like cargo, and real-time fluorescence microscopic visualization of dynein activation on microtubules and in solution. Together, the results of this proposal will provide an in-depth understanding of how adaptor proteins increase the functional plasticity of the dynein motor, and increase progress towards a holistic understanding of how trafficking is coordinated across the entire cell. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.