1s5r
Solution Structure of HBP1 SID-mSin3A PAH2 Complex
Structural highlights
FunctionHBP1_MOUSE Transcriptional repressor that binds to the promoter region of target genes. Plays a role in the regulation of the cell cycle and of the Wnt pathway. Binds preferentially to the sequence 5'-TTCATTCATTCA-3'. Binding to the H1F0 promoter is enhanced by interaction with RB1. Disrupts the interaction between DNA and TCF4 (By similarity).[1] 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 PubMedRecruitment of the histone deacetylase (HDAC)-associated Sin3 corepressor is an obligatory step in many eukaryotic gene silencing pathways. Here we show that HBP1, a cell cycle inhibitor and regulator of differentiation, represses transcription in a HDAC/Sin3-dependent manner by targeting the mammalian Sin3A (mSin3A) PAH2 domain. HBP1 is unrelated to the Mad1 repressor for which high-resolution structures in complex with PAH2 have been described. We show that like Mad1, the HBP1 transrepression domain binds through a helical structure to the hydrophobic cleft of mSin3A PAH2. Notably, the HBP1 helix binds PAH2 in a reversed orientation relative to Mad1 and, equally unexpectedly, this is correlated with a chain reversal of the minimal Sin3 interaction motifs. These results not only provide insights into how multiple, unrelated transcription factors recruit the same coregulator, but also have implications for how sequence similarity searches are conducted. HBP1 and Mad1 repressors bind the Sin3 corepressor PAH2 domain with opposite helical orientations.,Swanson KA, Knoepfler PS, Huang K, Kang RS, Cowley SM, Laherty CD, Eisenman RN, Radhakrishnan I Nat Struct Mol Biol. 2004 Aug;11(8):738-46. Epub 2004 Jul 4. PMID:15235594[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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