Download MendeleyMolecular functions of the TLE tetramerization domain in Wnt target gene repression.
Chodaparambil, J.V., Pate, K.T., Hepler, M.R., Tsai, B.P., Muthurajan, U.M., Luger, K., Waterman, M.L., Weis, W.I.(2014) EMBO J 33: 719-731
- PubMed: 24596249
- DOI: https://doi.org/10.1002/embj.201387188
- Primary Citation of Related Structures:
4OM2, 4OM3 - PubMed Abstract:
Wnt signaling activates target genes by promoting association of the co-activator β-catenin with TCF/LEF transcription factors. In the absence of β-catenin, target genes are silenced by TCF-mediated recruitment of TLE/Groucho proteins, but the molecular basis for TLE/TCF-dependent repression is unclear. We describe the unusual three-dimensional structure of the N-terminal Q domain of TLE1 that mediates tetramerization and binds to TCFs. We find that differences in repression potential of TCF/LEFs correlates with their affinities for TLE-Q, rather than direct competition between β-catenin and TLE for TCFs as part of an activation-repression switch. Structure-based mutation of the TLE tetramer interface shows that dimers cannot mediate repression, even though they bind to TCFs with the same affinity as tetramers. Furthermore, the TLE Q tetramer, not the dimer, binds to chromatin, specifically to K20 methylated histone H4 tails, suggesting that the TCF/TLE tetramer complex promotes structural transitions of chromatin to mediate repression.
Organizational Affiliation:
Departments of Structural Biology and Molecular & Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.
