1nwq
From Proteopedia
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CRYSTAL STRUCTURE OF C/EBPALPHA-DNA COMPLEX
Overview
CCAAT/enhancer-binding proteins (C/EBPs) are basic region leucine zipper, (bZIP) transcription factors that regulate cell differentiation, growth, survival, and inflammation. To understand the molecular basis of DNA, recognition by the C/EBP family we determined the x-ray structure of a, C/EBPalpha bZIP polypeptide bound to its cognate DNA site, (A(-5)T(-4)T(-3)G(-2)C(-1)G(1)C(2)A(3)A(4)T(5)) and characterized several, basic region mutants. Binding specificity is provided by interactions of, basic region residues Arg(289), Asn(292), Ala(295), Val(296), Ser(299), and Arg(300) with DNA bases. A striking feature of the C/EBPalpha, protein-DNA interface that distinguishes it from known bZIP-DNA complexes, is the central role of Arg(289), which is hydrogen-bonded to base A(3), phosphate, Asn(292) (invariant in bZIPs), and Asn(293). The conformation, of Arg(289) is also restricted by Tyr(285). In accordance with the, structural model, mutation of Arg(289) or a pair of its interacting, partners (Tyr(285) and Asn(293)) abolished C/EBPalpha binding activity., Val(296) (Ala in most other bZIPs) contributes to C/EBPalpha specificity, by discriminating against purines at position -3 and imposing steric, restraints on the invariant Arg(300). Mutating Val(296) to Ala strongly, enhanced C/EBPalpha binding to cAMP response element (CRE) sites while, retaining affinity for C/EBP sites. Thus, Arg(289) is essential for, formation of the complementary protein-DNA interface, whereas Val(296), functions primarily to restrict interactions with related sequences such, as CRE sites rather than specifying binding to C/EBP sites. Our studies, also help to explain the phenotypes of mice carrying targeted mutations in, the C/EBPalpha bZIP region.
About this Structure
1NWQ is a Single protein structure of sequence from Rattus norvegicus. Full crystallographic information is available from OCA.
Reference
Structural basis for DNA recognition by the basic region leucine zipper transcription factor CCAAT/enhancer-binding protein alpha., Miller M, Shuman JD, Sebastian T, Dauter Z, Johnson PF, J Biol Chem. 2003 Apr 25;278(17):15178-84. Epub 2003 Feb 10. PMID:12578822
Page seeded by OCA on Tue Nov 20 22:36:54 2007
