Motor proteins serve a number of functions in the cell, including helping transport biological molecules (cargo) to where they belong. One such motor protein, dynein, is important for moving cargo from the periphery of cells toward the center. In human cells, dynein needs to partner with another protein (dynactin) in order to move cargo across long distances, such as along nerve cells. The control or regulation of how these two proteins interact determines what, when, and where cargo are transported in a cell. With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Nikolaus Loening from Lewis & Clark College to determine how the interactions between these two proteins are regulated by changes in the structure of dynein. Dr. Loening focuses on dynein intermediate chain, a part of the motor protein that initiates binding with dynactin, and studies how variations in its sequence and the addition of phosphate chemical groups change its binding behavior. The intermediate chain is difficult to study because it does not normally adopt a fixed and rigid shape; it is intrinsically disordered. Consequently, a variety of biophysical techniques are used to study the effects of these structural variations on the intermediate chain’s shape and its interactions with dynactin. This project provides undergraduate and high school students with opportunities to participate directly in this research. In addition, some parts of this research are incorporated into laboratory and special topics classes at Lewis & Clark College, thereby broadening participation in this project to include a larger number of undergraduate students.
This research project characterizes the structural properties of a little-studied isoform of the dynein intermediate chain (IC) to better localize the interaction between IC and its binding partners. The objective of this project is to develop a structural model for how an intrinsically disordered region of IC binds with the p150Glued subunit of dynactin. Results from these studies lead to insights into how this interaction is regulated by the isoform type or phosphorylation state of dynein. The dynamic nature of this system makes it difficult to study by cryo-electron microscopy or X-ray crystallography. In addition, the complex has characteristics that make it unfavorable for study by conventional NMR methods. This project uses a combination of mutagenesis to stabilize p150Glued combined with better localization of the binding site to allow the development of smaller, more tractable constructs that are providing high-resolution structural information. This work helps to develop an understanding for how this system is regulated, which further complements studies on the less dynamic regions of the dynein complex. In the course of this research, new methods for protein NMR spectroscopy are developed to benefit not only researchers studying dynein and intrinsically disordered proteins, but the protein NMR community at large.
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.
