Interaction of vanadate oligomers and permolybdate with the 90-kDa heat-shock protein, Hsp90

The 90-kDa heat-shock protein (Hsp90) is a molecular chaperone that aids the folding of nuclear hormone receptors and protein kinases. Hsp90 protein complexes can be stabilized by molybdate and by other transition metal oxyanions such as vanadate. Our earlier findings [Csermely, P., Kajtar, J., Hollosi, M., Jalsovszky, G., Holly, S., Kahn, C. R., Gergely, P. Jr, Soti, C., Mihaly, K. & Somogyi, J. (1993) J. Biol. Chem. 268, 1901-1907] showed that vanadate and molybdate can induce a large conformational change of Hsp90. Here we provide direct evidence for the binding of vanadate and molybdate to Hsp90 by demonstrating that surface-plasmon-resonance measurements indicate binding of various vanadate oligomers to Hsp90, V-51-NMR measurements show an extensive interaction of decavanadate with the chaperone, and permolybdate treatment of Hsp90 induces a marked mobility shift of the protein and its tryptic fragments. Our results indicate the flexibility of molybdate/vanadate-binding sites of Hsp90, which are able to accomodate various species of these transition metal anions.