Prof. Chittaranjan Das, Purdue University

Regulation of Catalytic Activity of Deubiquitinases

Biochemistry Seminar Series

Ubiquitination, the post-translational modification of proteins by covalent attachment of ubiquitin, is widely used to control cellular processes. A group of enzymes collectively known as deubiquitinases (DUBs) can counter ubiquitination by removing ubiquitin from modified proteins. The human genome encodes for about 100 such enzymes. The mechanism of their catalytic activity, their biological function and role in pathogenesis are being studied by a number of labs around the world. Our main interest in this area is to understand the mechanisms underlying regulation of their catalytic activity. A case study of one such enzyme called UCHL1, a protein mutated in Parkinson’s disease (PD), shows an unusual mode of substrate-mediated regulation of catalytic activity that may have broader implications for understanding substrate selectivity in this class of enzymes. We present structural (X-ray and NMR) and biochemical data on the I93M PD mutant of the enzyme, which indicate that the mutation destabilizes the protein leading to partial exposure of its hydrophobic core. Additionally, structural studies on a proteasome-associated DUB will be presented explaining some of its function on the proteasome.     

For more information contact Prof. Raquel Lieberman (404-385-3663).