3fs1 | pdb_00003fs1
Crystal structure of HNF4a LBD in complex with the ligand and the coactivator PGC-1a fragment
Structural highlights
DiseaseHNF4A_HUMAN Defects in HNF4A are the cause of maturity-onset diabetes of the young type 1 (MODY1) [MIM:125850; also symbolized MODY-1. MODY is a form of diabetes that is characterized by an autosomal dominant mode of inheritance, onset in childhood or early adulthood (usually before 25 years of age), a primary defect in insulin secretion and frequent insulin-independence at the beginning of the disease.[1] [2] [3] FunctionHNF4A_HUMAN Transcriptionally controlled transcription factor. Binds to DNA sites required for the transcription of alpha 1-antitrypsin, apolipoprotein CIII, transthyretin genes and HNF1-alpha. May be essential for development of the liver, kidney and intestine. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedHepatocyte nuclear factor 4alpha (HNF4alpha) is a novel nuclear receptor that participates in a hierarchical network of transcription factors regulating the development and physiology of such vital organs as the liver, pancreas, and kidney. Among the various transcriptional coregulators with which HNF4alpha interacts, peroxisome proliferation-activated receptor gamma (PPARgamma) coactivator 1alpha (PGC-1alpha) represents a novel coactivator whose activation is unusually robust and whose binding mode appears to be distinct from that of canonical coactivators such as NCoA/SRC/p160 family members. To elucidate the potentially unique molecular mechanism of PGC-1alpha recruitment, we have determined the crystal structure of HNF4alpha in complex with a fragment of PGC-1alpha containing all three of its LXXLL motifs. Despite the presence of all three LXXLL motifs available for interactions, only one is bound at the canonical binding site, with no additional contacts observed between the two proteins. However, a close inspection of the electron density map indicates that the bound LXXLL motif is not a selected one but an averaged structure of more than one LXXLL motif. Further biochemical and functional studies show that the individual LXXLL motifs can bind but drive only minimal transactivation. Only when more than one LXXLL motif is involved can significant transcriptional activity be measured, and full activation requires all three LXXLL motifs. These findings led us to propose a model wherein each LXXLL motif has an additive effect, and the multiple binding modes by HNF4alpha toward the LXXLL motifs of PGC-1alpha could account for the apparent robust activation by providing a flexible mechanism for combinatorial recruitment of additional coactivators and mediators. Multiple binding modes between HNF4alpha and the LXXLL motifs of PGC-1alpha lead to full activation.,Rha GB, Wu G, Shoelson SE, Chi YI J Biol Chem. 2009 Dec 11;284(50):35165-76. Epub 2009 Oct 21. PMID:19846556[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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