1ywt
From Proteopedia
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'''Crystal structure of the human sigma isoform of 14-3-3 in complex with a mode-1 phosphopeptide''' | '''Crystal structure of the human sigma isoform of 14-3-3 in complex with a mode-1 phosphopeptide''' | ||
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[[Category: Yaffe, M B.]] | [[Category: Yaffe, M B.]] | ||
[[Category: 14-3-3]] | [[Category: 14-3-3]] | ||
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| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 16:53:44 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 13:53, 3 May 2008
Crystal structure of the human sigma isoform of 14-3-3 in complex with a mode-1 phosphopeptide
Overview
The 14-3-3 family of proteins includes seven isotypes in mammalian cells that play numerous diverse roles in intracellular signaling. Most 14-3-3 proteins form homodimers and mixed heterodimers between different isotypes, with overlapping roles in ligand binding. In contrast, one mammalian isoform, 14-3-3sigma, expressed primarily in epithelial cells, appears to play a unique role in the cellular response to DNA damage and in human oncogenesis. The biological and structural basis for these 14-3-3sigma-specific functions is unknown. We demonstrate that endogenous 14-3-3sigma preferentially forms homodimers in cells. We have solved the x-ray crystal structure of 14-3-3sigma bound to an optimal phosphopeptide ligand at 2.4 angstroms resolution. The structure reveals the presence of stabilizing ring-ring and salt bridge interactions unique to the 14-3-3sigma homodimer structure and potentially destabilizing electrostatic interactions between subunits in 14-3-3sigma-containing heterodimers, rationalizing preferential homodimerization of 14-3-3sigma in vivo. The interaction of the phosphopeptide with 14-3-3 reveals a conserved mechanism for phospho-dependent ligand binding, implying that the phosphopeptide binding cleft is not the critical determinant of the unique biological properties of 14-3-3sigma. Instead, the structure suggests a second ligand binding site involved in 14-3-3sigma-specific ligand discrimination. We have confirmed this by site-directed mutagenesis of three sigma-specific residues that uniquely define this site. Mutation of these residues to the alternative sequence that is absolutely conserved in all other 14-3-3 isotypes confers upon 14-3-3sigma the ability to bind to Cdc25C, a ligand that is known to bind to other 14-3-3 proteins but not to sigma.
About this Structure
1YWT is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
A structural basis for 14-3-3sigma functional specificity., Wilker EW, Grant RA, Artim SC, Yaffe MB, J Biol Chem. 2005 May 13;280(19):18891-8. Epub 2005 Feb 24. PMID:15731107 Page seeded by OCA on Sat May 3 16:53:44 2008
