S100B(betabeta) inhibits the protein kinase C-dependent phosphorylation of a peptide derived from p53 in a Ca2+-dependent manner.
S100B(betabeta) is a dimeric Ca2+-binding protein that is known to inhibit the protein kinase C (PKC)-dependent phosphorylation of several proteins. To further characterize this inhibition, we synthesized peptides based on the PKC phosphorylation domains of p53 (residues 367-388), neuromodulin (residues 37-53), and the regulatory domain of PKC (residues 19-31), and tested them as substrates for PKC. All three peptides were shown to be good substrates for the catalytic domain of PKC. As for full-length p53 (Baudier J, Delphin C, Grunwald D, Khochbin S, Lawrence JJ. 1992. Proc Natl Acad Sci USA 89:11627-11631), S100B(betabeta) binds the p53 peptide and inhibits its PKC-dependent phosphorylation (IC50 = 10 +/- 7 microM) in a Ca2+-dependent manner. Similarly, phosphorylation of the neuromodulin peptide and the PKC regulatory domain peptide were inhibited by S100B(betabeta) in the presence of Ca2+ (IC50 = 17 +/- 5 microM; IC50 = 1 +/- 0.5 microM, respectively). At a minimum, the C-terminal EF-hand Ca2+-binding domain (residues 61-72) of each S100beta subunit must be saturated to inhibit phosphorylation of the p53 peptide as determined by comparing the Ca2+ dependence of inhibition ([Ca]IC50 = 29.3 +/- 17.6 microM) to the dissociation of Ca2+ from the C-terminal EF-hand Ca2+-binding domain of S100B(betabeta).
Wilder
P T
PT
Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore 21201, USA.
Rustandi
R R
RR
Drohat
A C
AC
Weber
D J
DJ
D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000502:physiology; D019922:GAP-43 Protein / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors; D010446:Peptide Fragments; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D051381:Rats; D011994:Recombinant Proteins; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000378:metabolism*; D016415:Sequence Alignment; D013379:Substrate Specificity; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D019922:GAP-43 Protein; D009414:Nerve Growth Factors; D010446:Peptide Fragments; D011994:Recombinant Proteins; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; C579160:S100B protein, human; C579158:S100b protein, rat; D016159:Tumor Suppressor Protein p53; D011493:Protein Kinase C; D002118:Calcium