ATP induces a conformational change of the 90-kDa heat shock protein (hsp90).
The 90-kDa heat shock protein (hsp90) is a well conserved, abundant cytosolic protein believed to be a "chaperone" of most steroid receptors. We have recently demonstrated that hsp90 has an ATP-binding site and autophosphorylating activity (Csermely, P., and Kahn, C. R. (1991) J. Biol. Chem. 266, 4943-4950). Circular dichroism analysis of highly purified hsp90 from rat liver shows that ATP induces an increase of beta-pleated sheet content of hsp90. Vanadate, molybdate, and heat treatment at 56 degrees C induce a similar change in the circular dichroism spectrum. Fourier transformed infrared spectroscopy reveals an ATP-induced increase in the interchain interactions of the 90-kDa heat shock protein due to an increase in its beta-pleated sheet content. In further studies we found that ATP: 1) decreases the tryptophan fluorescence of hsp90 by 11.6 +/- 1.9%; 2) increases the hydrophobic character of the protein as determined by its distribution between an aqueous phase and phenyl-Sepharose; and 3) renders hsp90 less susceptible to tryptic digestion. Our results suggest that hsp90 undergoes an "open-->closed" conformational change after the addition of ATP, analogous in many respects to the similar changes of the DnaK protein, the immunoglobulin heavy chain binding protein (BiP/GRP78), and hsp70. The ATP-induced conformational change of hsp90 may be important in regulating its association with steroid receptors and other cellular proteins.
Csermely
P
P
Institute of Biochemistry I, Semmelweis University, School of Medicine, Budapest, Hungary.
Kajtár
J
J
Hollósi
M
M
Jalsovszky
G
G
Holly
S
S
Kahn
C R
CR
Gergely
P
P
Söti
C
C
Mihály
K
K
Somogyi
J
J
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002942:Circular Dichroism; D005583:Fourier Analysis; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism; D006358:Hot Temperature; D008099:Liver / Q000737:chemistry*; D008297:Male; D008982:Molybdenum / Q000494:pharmacology; D010446:Peptide Fragments / Q000378:metabolism; D010766:Phosphorylation; D011487:Protein Conformation / Q000187:drug effects; D017433:Protein Structure, Secondary / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013055:Spectrophotometry, Infrared; D014357:Trypsin / Q000378:metabolism; D014364:Tryptophan / Q000737:chemistry; D014638:Vanadates / Q000494:pharmacology
D006360:Heat-Shock Proteins; D010446:Peptide Fragments; C044659:molybdate; D014638:Vanadates; D008982:Molybdenum; D014364:Tryptophan; D000255:Adenosine Triphosphate; D014357:Trypsin