Interactions of Hsp90 with histones and related peptides

The 90 kDa heat shock protein (Hsp90) induces the condensation of the chrom atin structure [Csermely, P., Kajtar, J., Hollosi, M., Oikarinen, J., and S omogyi, J. (1994) Biochem. Biophys. Res. Commun. 202, 1657-1663]. In our pr esent studies we used surface plasmon resonance measurements to demonstrate that Hsp90 binds histones H1, H2A, H2B, H3 and H4 with high affinity havin g dissociation constants in the submicromolar range. Strong binding of the C-terminal peptide of histone H1 containing the SPKK-motif and a pentaeicos a-peptide including the Hsp90 bipartite nuclear localization signal sequenc e was also observed. However, a lysine/arginine-rich peptide of casein, and the lysine-rich platelet factor 4 did not display a significant interactio n with Hsp90. Histones and positively charged peptides modulated the Hsp90- associated kinase activity. Interactions between Hsp90, histones, and high mobility group (HMG) protein-derived peptides raise the possibility of the involvement of Hsp90 in chromatin reorganization during steroid action, mit osis, or after cellular stress.