The calmodulin-binding domain of the mouse 90-kDa heat shock protein.
The mouse 90-kDa heat shock protein (HSP90) and Ca(2+)-calmodulin were cross-linked at an equimolar ratio using a carbodiimide zero-length cross-linker. To identify the calmodulin-binding domain(s) of HSP90, CNBr-cleaved peptide fragments of HSP90 were mixed with Ca(2+)-calmodulin and cross-linked. Amino acid sequence determination revealed that an HSP90 alpha-derived peptide starting at the 486th amino acid residue was contained in the cross-linked products, which contains a calmodulin-binding motif (from Lys500 to Ile520). A similar motif is present also in HSP90 beta (from Lys491 to Val511). The synthetic peptides corresponding to these putative calmodulin-binding sequences were found to be cross-linked with Ca(2+)-calmodulin and to prevent the cross-linking of HSP90 and Ca(2+)-calmodulin. Both HSP90 alpha and HSP90 beta bind Ca2+. The HSP90 peptides bind HSP90 and thereby inhibit the binding of Ca2+. In addition, the HSP90 peptides augment the self-oligomerization of HSP90 induced at elevated temperatures. These results suggest that the calmodulin-binding domain of HSP90 might interact with another part of the same molecule and that Ca(2+)-calmodulin might modulate the structure and function of HSP90 through abolishing the intramolecular interaction.
Minami
Y
Y
Department of Cell Biology, Tokyo Metropolitan Institute of Medical Science, Japan.
Kawasaki
H
H
Suzuki
K
K
Yahara
I
I
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000302:isolation & purification / Q000378:metabolism*; D003432:Cross-Linking Reagents; D003488:Cyanogen Bromide; D004591:Electrophoresis, Polyacrylamide Gel; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D010455:Peptides / Q000138:chemical synthesis; D017433:Protein Structure, Secondary
D002147:Calmodulin; D003432:Cross-Linking Reagents; D006360:Heat-Shock Proteins; D010446:Peptide Fragments; D010455:Peptides; D003488:Cyanogen Bromide; D002118:Calcium