A molecular clamp in the crystal structure of the N-terminal domain of the yeast Hsp90 chaperone

Hsp90 is a highly specific chaperone for many signal transduction proteins, including steroid hormone receptors and a broad range of protein kinases. The crystal structure of the N-terminal domain of the yeast Hsp90 reveals a dimeric structure based on a highly twisted sixteen stranded β-sheet, whose topology suggests a possible 3D-domain-swapped structure for the intact Hsp90 dimer. The opposing faces of the β-sheets in the dimer define a potential peptide-binding cleft, suggesting that the N-domain may serve as a molecular ‘clamp’ in the binding of ligand proteins to Hsp90.