Our research focuses on understanding how the cell cycle is regulated by ubiquitin-mediated proteolysis using x-ray crystallography as a primary tool. Progression through the cell cycle is coordinated by the cyclin-dependent kinases (CDKs) and their activating cyclin subunits as well as a series of CKI inhibitors. Control of the oscillations of the cyclins and CKIs by ubiquitin-dependent proteolysis plays a critical role in cell cycle regulation. Deregulation of the cyclins and CKIs can cause aberrant proliferation and genomic instability. Indeed, the eukaryotic cell cycle is one of the most frequently altered cellular processes identified in cancer.

Proteins degraded by the ubiquitin-mediated proteolysis must be covalently linked to the small protein ubiquitin. Ubiquitin serves as a molecular tag that marks proteins for degradation by the 26S proteasome. The selection of substrates for ubiquitination is prescribed by a specific class of enzymes called ubiquitin-protein ligases (also known as E3s). Most E3 ligases comprise a large superfamily of protein-protein complexes. They bind the substrate protein and a cognate ubiquitin-conjugating enzyme (E2), and catalyze the transfer of ubiquitin from the E2 to specific lysine residues within the substrate. Thus E3s are responsible for both ubiquitin transfer and specific recognition of each of the target proteins. However, the molecular details underlying these two processes remain poorly understood.

The overall goal of our research is to use SCF ubiquitin ligases as a model system to elucidate the structural and mechanistic basis of substrate recognition, lysine specificity, ubiquitin transfer, and the role of CDK in CKI degradation. Our long-term objective is to gain a detailed understanding of the structure, function, and regulation of APC/C and Cul3-based ubiquitin ligases, and to use this knowledge to elucidate how defects of the ubiquitin system can lead to cancer and neurodegenerative diseases.

If you are interested in conducting postdoctoral or graduate research in our laboratory or would like more information, please contact Bing Hao at bhao@uchc.edu.

Accepting Lab Rotation Students: Summer 2022, Fall 2022, and Spring 2023

Lab Rotation Projects
--Elucidation of the mechanism that regulates the substrate lysine selection by E2 and E3 during ubiquitin transfer.
--Structural characterization of the E2-SCF E3 interaction and its role in the ubiquitin transfer process.
--Structural studies of the SCF E3-substrate complexes.

Journal Articles

Book Chapters