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Metal ions modulate the folding and stability of the tumor suppressor protein S100A2
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Orientador(es)
Resumo(s)
The EF-hand protein S100A2 is a cell cycle regulator involved in tumorigenesis, acting through regulation of the p53 activation state. Metal ion-free S100A2 is homodimeric and contains two Ca2+-binding sites and two Zn2+-binding sites per subunit, whereby the Zn2+ ion binding to one of the sites is coordinated by residues from two homodimers. The effect of selective binding of these metal ions was investigated using site-specific mutants which lacked one or both zinc sites. CD analysis of secondary structure changes on metallation showed that Zn2+ binding was associated with a decrease in the secondary structure content, whereas Ca2+ had the opposite effect in two of the three S100A2 mutants studied. The energy of unfolding DeltaGU of the apo wild-type S100A2 was determined to be 89.9 kJ.mol-1, and the apparent midpoint transition temperature (Tmapp) was 58.4ºC. In addition, a detailed study of the urea and thermal unfolding of the S100A2 mutants in different metallation states (apo, Zn2+ and Ca2+) was performed. Thermal denaturation experiments showed that Zn2+ acts as a destabilizer and Ca2+ as a stabilizer of the protein conformation. This suggests a synergistic effect between metal binding, protein stability and S100A2 biological activity, according to which Ca2+ activates and stabilizes the protein, the opposite being observed on Zn2+ binding.
Descrição
Febs Journal (2009)276:1776-1786
Palavras-chave
cancer metals p53 protein stability protein structure and folding
Contexto Educativo
Citação
Botelho, H. M., Koch, M., Fritz, G., and Gomes, C. M. (2009) Metal ions modulate the folding and stability of the tumor suppressor protein S100A2, Febs J 276, 1776-1786
Editora
Wiley