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CRYSTAL STRUCTURE OF C/EBPALPHA-DNA COMPLEX
Structural highlights
FunctionCEBPA_RAT C/EBP is a DNA-binding protein that recognizes two different motifs: the CCAAT homology common to many promoters and the enhanced core homology common to many enhancers. 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 PubMedCCAAT/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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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