2FWY: Structure Of Human Hsp90-Alpha Bound To The Potent Water Soluble Inhibitor Pu-H64

Hsp90 chaperones play a critical role in modulating the activity of many cell signaling proteins and are an attractive target for anti-cancer therapeutics. We report here the structures of the water soluble 8-aryl-sulfanyl adenine class Hsp90 inhibitors, 1 (PU-H71) and 2 (PU-H64), in complex with the N-terminal domain of human Hsp90alpha. The conformation of 1 when bound to Hsp90 differs from previously reported 8-aryl adenine Hsp90 inhibitors including 3 (PU24FCl). While the binding mode for 3 places the 2'-halide of the 8-aryl group on top of the adenine ring, for 1 and 2, we show that the 2'-halide is rotated approximately 180 degrees away. This difference explains the opposing trends in Hsp90 inhibitory activity for the 2'-halo derivatives of the 3',4',5'-trimethoxy series where Cl > Br > I compared to the 4',5'-methylenedioxy series where I > Br > Cl. We also present quantum chemical calculations of 2 and its analogues that illuminate their basis for Hsp90 inhibition. The calculated conformation of 2 agreed well with the crystallographically observed conformations of 1 and 2. The predictive nature of the calculations has allowed the exploration of additional derivatives based on the 8-aryl adenine scaffold.
PDB ID: 2FWYDownload
MMDB ID: 41514
PDB Deposition Date: 2006/2/3
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 2.1  Å
Source Organism:
Similar Structures:
Biological Unit for 2FWY: monomeric; determined by author
Molecular Components in 2FWY
Label Count Molecule
Protein (1 molecule)
Heat Shock Protein HSP 90-alpha(Gene symbol: HSP90AA1)
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

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