1e91

Publication Abstract from PubMed

Sin3A or Sin3B are components of a corepressor complex that mediates repression by transcription factors such as the helix-loop-helix proteins Mad and Mxi. Members of the Mad/Mxi family of repressors play important roles in the transition between proliferation and differentiation by down-regulating the expression of genes that are activated by the proto-oncogene product Myc. Here, we report the solution structure of the second paired amphipathic helix (PAH) domain (PAH2) of Sin3B in complex with a peptide comprising the N-terminal region of Mad1. This complex exhibits a novel interaction fold for which we propose the name 'wedged helical bundle'. Four alpha-helices of PAH2 form a hydrophobic cleft that accommodates an amphipathic Mad1 alpha-helix. Our data further show that, upon binding Mad1, secondary structure elements of PAH2 are stabilized. The PAH2-Mad1 structure provides the basis for determining the principles of protein interaction and selectivity involving PAH domains.

The Mad1-Sin3B interaction involves a novel helical fold.,Spronk CA, Tessari M, Kaan AM, Jansen JF, Vermeulen M, Stunnenberg HG, Vuister GW Nat Struct Biol. 2000 Dec;7(12):1100-4. PMID:11101889^[3]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.