Structure, allosterics, interactions and function of Hsp70 Chaperones
Erik R.P. Zuiderweg, Ph.D.
Professor of Biological Chemistry
Hsp70 proteins mediate trafficking, folding and refolding of proteins in all known cellular structures. Damage to these proteins is fatal; overexpression of these proteins is observed in stressed cells, such as in cancerous tissues. As such Hsp70's are a target for the treatment of especially breast cancer. These Heat Shock Proteins are 70 kDa, and have a three domain structure: nucleotide-binding domain (45 kDa), substrate binding domain (15 kDa) and C-terminal domain (10 kDa). The chaperone helps the refolding of proteins by binding and release cycles (see pic) driven by an allosteric mechanism. We use high field NMR in solution (600 - 900 MHz) to study its structure, dynamics and interaction as a function of substrate, nucleotides and co-chaperones. We are working on full-length chaperone constructs in order to decipher the allosteric mechanism (see pic) and to help develop drugs (together with the Jason Gestwicki lab) to suppress its activity as an aid in Alzheimer therapy.
The understanding of protein function is incomplete without considering entropy, that is, dynamics. In enzymes, the active site is often dynamic to be able to adept to substrate, transition state and product; for protein complexes, the intermolecular interface sites are particularly dynamic to accomodate induced fits. Binding processes often involve perturbation of fast dynamical components, contributing (sometimes to a dominant extent) to the ligand binding entropy and hence ligand binding free energy (= affinity). NMR plays an important role in experimentally measuring dynamics in proteins at time scales ranging from seconds to pico seconds. Our mission is to develop and apply methods to describe what the motions actually are.