Research:

Hsp90 is an essential eukaryotic molecular chaperone that accounts for 1-2% of all cytosolic proteins. It is required for the maturation and maintenance of a wide range of client proteins that primarily belong to signaling and regulatory pathways. In particular, Cdk4, a vital serine/threonine kinase involved in cell cycle regulation, requires Hsp90 for proper maturation. Cdk4 maturation also requires the cochaperone Cdc37. Despite its critical importance, virtually nothing is known about how Hsp90 ATPase activity, related conformational changes, or the cochaperone Cdc37 effect kinase activation. A first step in answering these questions, is to investigate nucleotide driven conformational changes of Hsp90. Recent crystal structures of the bacterial homolog HtpG in both the apo- and ADP-bound state give some insight into nucleotide dependent conformational changes. Using fluorescence assays and SAXS, I am further investigating nucleotide dependent conformations. Attempts are also being made at crystallizing full-length HtpG in the presence of AMP-PNP and AMP.

The information gained from the simpler E. coli system will be applied to the human Hsp90 and looked at in the context of larger complexes. I will first study the role of Cdc37 and other cochaperones in establishing conformational equilibria. Ultimately, I want to answer the question of how conformational changes in Hsp90 correlate with its biological function by investigating the Hsp90-dependent activation of Cdk4. Stable complexes will also be studied crystallographically in order to gain structural insight into the molecular mechanism of Hsp90.

Publications:

Krukenberg KA, Förster F, Rice LM, Sali A, Agard DA., "Multiple Conformations of E. coli Hsp90 in Solution: Insights into the Conformational Dynamics of Hsp90." Structure. (2008), 16(5), 755-65. (pdf, supplemental data)

Kung C, Kenski DM, Krukenberg K, Madhani HD, Shokat KM. Selective kinase inhibition by exploiting differential pathway sensitivity. Chem Biol. 2006 Apr;13(4):399-407.