Structural changes in the C-terminus of Ca2+-bound rat S100B (beta beta) upon binding to a peptide derived from the C-terminal regulatory domain of p53.

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TitleStructural changes in the C-terminus of Ca2+-bound rat S100B (beta beta) upon binding to a peptide derived from the C-terminal regulatory domain of p53.
Publication TypeJournal Article
Year of Publication1999
AuthorsRustandi, RR, Baldisseri, DM, Drohat, AC, Weber, DJ
JournalProtein Sci
Date Published1999 Sep
KeywordsAmino Acid Sequence, Animals, Calcium-Binding Proteins, Dimerization, Models, Molecular, Molecular Sequence Data, Nerve Growth Factors, Nuclear Magnetic Resonance, Biomolecular, Peptide Fragments, Protein Binding, Protein Conformation, Protein Structure, Secondary, Protein Structure, Tertiary, Rats, S100 Proteins, Tumor Suppressor Protein p53

S100B(beta beta) is a dimeric Ca2+-binding protein that interacts with p53, inhibits its phosphorylation by protein kinase C (PKC) and promotes disassembly of the p53 tetramer. Likewise, a 22 residue peptide derived from the C-terminal regulatory domain of p53 has been shown to interact with S100B(beta beta) in a Ca2+-dependent manner and inhibits its phosphorylation by PKC. Hence, structural studies of Ca2+-loaded S100B(beta beta) bound to the p53 peptide were initiated to characterize this interaction. Analysis of nuclear Overhauser effect (NOE) correlations, amide proton exchange rates, 3J(NH-H alpha) coupling constants, and chemical shift index data show that, like apo- and Ca2+-bound S100B(beta beta), S100B remains a dimer in the p53 peptide complex, and each subunit has four helices (helix 1, Glu2-Arg20; helix 2, Lys29-Asn38; helix 3, Gln50-Asp61; helix 4, Phe70-Phe87), four loops (loop 1, Glu21-His25; loop 2, Glu39-Glu49; loop 3, Glu62-Gly66; loop 4, Phe88-Glu91), and two beta-strands (beta-strand 1, Lys26-Lys28; beta-strand 2, Glu67-Asp69), which forms a short antiparallel beta-sheet. However, in the presence of the p53 peptide helix 4 is longer by five residues than in apo- or Ca2+-bound S100B(beta beta). Furthermore, the amide proton exchange rates in helix 3 (K55, V56, E58, T59, L60, D61) are significantly slower than those of Ca2+-bound S100B(beta beta). Together, these observations plus intermolecular NOE correlations between the p53 peptide and S100B(beta beta) support the notion that the p53 peptide binds in a region of S100B(beta beta), which includes residues in helix 2, helix 3, loop 2, and the C-terminal loop, and that binding of the p53 peptide interacts with and induces the extension of helix 4.

Alternate JournalProtein Sci.
PubMed ID10493575
PubMed Central IDPMC2144411
Grant ListR01GM58888 / GM / NIGMS NIH HHS / United States