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Título: Rearrangements in thyroid hormone receptor charge clusters that stabilize bound 3,5',5-triiodo-l-thyronine and inhibit homodimer formation
Autor(es): Togashi, Marie
Nguyen, Phuong
Fletterick, Robert J.
Baxter, John Darling
Webb, Paul
Assunto: Tireóide - hormônios
Receptor do hormônio tireoideano
Data de publicação: 2005
Editora: The American Society for Biochemistry and Molecular Biology, Inc.
Referência: TOGASHI, Marie et al. Rearrangements in thyroid hormone receptor charge clusters that stabilize bound 3,5_,5-triiodo-l-thyronine and inhibit homodimer formation. The Journal of Biological Chemistry, v. 280, n. 27, p. 25665-25673, 2005. Disponível em: <http://www.jbc.org/content/280/27/25665.full.pdf+html>. Acesso em: 3 jun. 2013.
Resumo: In this study, we investigated how thyroid hormone (3,5′,5-triiodo-l-thyronine, T3) inhibits binding of thyroid hormone receptor (TR) homodimers, but not TR-retinoid X receptor heterodimers, to thyroid hormone response elements. Specifically we asked why a small subset of TRβ mutations that arise in resistance to thyroid hormone syndrome inhibit both T3 binding and formation of TRβ homodimers on thyroid hormone response elements. We reasoned that these mutations may affect structural elements involved in the coupling of T3 binding to inhibition of TR DNA binding activity. Analysis of TR x-ray structures revealed that each of these resistance to thyroid hormone syndrome mutations affects a cluster of charged amino acids with potential for ionic bond formation between oppositely charged partners. Two clusters (1 and 2) are adjacent to the dimer surface at the junction of helices 10 and 11. Targeted mutagenesis of residues in Cluster 1 (Arg338, Lys342, Asp351, and Asp355) and Cluster 2 (Arg429, Arg383, and Glu311) confirmed that the clusters are required for stable T3 binding and for optimal TR homodimer formation on DNA but also revealed that different arrangements of charged residues are needed for these effects. We propose that the charge clusters are homodimer-specific extensions of the dimer surface and further that T3 binding promotes specific rearrangements of these surfaces that simultaneously block homodimer formation on DNA and stabilize the bound hormone. Our data yield insight into the way that T3 regulates TR DNA binding activity and also highlight hitherto unsuspected T3-dependent conformational changes in the receptor ligand binding domain.
Licença: The Journal of Biological Chemistry - Authors need NOT contact the journal to obtain rights to reuse their own material. They are automatically granted permission to do the following: Reproduce an article for use in the author's courses. (If the author is employed by an academic institution, that institution also may reproduce the article for teaching purposes.). Fonte: http://www.jbc.org/site/misc/Copyright_Permission.xhtml. Acesso em: 20 maio 2013.
DOI: https://dx.doi.org/10.1074/jbc.M501615200
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