CAREER: Biochemical and Structural Mechanism of the WASH Regulatory Complex

Like a city, the cell is filled with heavy traffic. Cellular traffic is made up of tiny parcels called vesicles that contain molecules to be sent to their correct destinations. Movement of traffic allows the cell to perform important tasks, such as responding to the environment, absorbing nutrients, and surviving.

Larger membrane-enclosed structures called endosomes act as a “parcel distribution center” to decide where the molecules are sent to. Endosomes are coated with fibers made up of a protein called actin. Similar to muscles and bones in the human body, actin fibers give endosomes proper shape and strength.

Without actin, the endosome collapses, and the traffic stalls. The overall goal of this project is to understand how the cell produces actin fibers to support the structure and function of endosomes. Results of this project will provide fundamental knowledge about how endosomes form correct structures and direct traffic properly.

In parallel, the PI will integrate multiple new approaches to improve the infrastructure of biochemical education and research, including creating new virtual lab software to help undergraduate students study biochemistry lab courses, establishing a bimonthly campus-wide biological science forum to help graduate students and labs share research and collaborate, and offering strong undergraduate research experiences both in the traditional lab setting and in a new virtual group-discussion format.

The overall goal of this project is to understand actin cytoskeletal regulation at endosomal membranes. Specifically focused on a central regulator of endosomal actin named the WASH Regulatory Complex (SHRC), the project aims to: 1) determine how the SHRC is activated by various membrane ligands; 2) identify and characterize new membrane ligands, and; 3) solve high-resolution structures of the SHRC in various activation states.

Successful completion of the project will fill a large gap in understanding how actin structures are dynamically assembled at endosomal membranes, how actin rearrangements regulate endosomal structure and function, and how the cell may use similar principles to control actin dynamics at other intracellular organelles and trafficking pathways. In addition, the project will develop new proteomic tools, discover new molecules important to endosomal trafficking, and identify new structural mechanisms, which together will provide unprecedented opportunities for biologists to manipulate and study endosomal trafficking in cells.

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.