title: Structure and Function of the Su(H)-Hairless Repressor Complex, the Major Antagonist of Notch Signaling in Drosophila melanogaster.
abstract: Notch is a conserved signaling pathway that specifies cell fates in metazoans. Receptor-ligand interactions induce changes in gene expression, which is regulated by the transcription factor CBF1/Su(H)/Lag-1 (CSL). CSL interacts with coregulators to repress and activate transcription from Notch target genes. While the molecular details of the activator complex are relatively well understood, the structure-function of CSL-mediated repressor complexes is poorly defined. In Drosophila, the antagonist Hairless directly binds Su(H) (the fly CSL ortholog) to repress transcription from Notch targets. Here, we determine the X-ray structure of the Su(H)-Hairless complex bound to DNA. Hairless binding produces a large conformational change in Su(H) by interacting with residues in the hydrophobic core of Su(H), illustrating the structural plasticity of CSL molecules to interact with different binding partners. Based on the structure, we designed mutants in Hairless and Su(H) that affect binding, but do not affect formation of the activator complex. These mutants were validated in vitro by isothermal titration calorimetry and yeast two- and three-hybrid assays. Moreover, these mutants allowed us to solely characterize the repressor function of Su(H) in vivo.
authors.affiliation: Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Yuan
authors.affiliation: Universität Hohenheim, Institut für Genetik, Stuttgart, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Praxenthaler
authors.affiliation: Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America.
authors.forename: Nassif
authors.identifier: 0000-0002-3964-8512
authors.initials: N
authors.lastname: Tabaja
authors.affiliation: Centre for Molecular Informatics, Department of Chemistry, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Rubben
authors.initials: R
authors.lastname: Torella
authors.affiliation: Universität Hohenheim, Institut für Genetik, Stuttgart, Germany.
authors.forename: Anette
authors.initials: A
authors.lastname: Preiss
authors.affiliation: Universität Hohenheim, Institut für Genetik, Stuttgart, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Maier
authors.affiliation: Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America.
authors.forename: Rhett A
authors.initials: RA
authors.lastname: Kovall
mesh_terms: D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry; D029721:Drosophila Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster; D057927:Hydrophobic and Hydrophilic Interactions; D056004:Molecular Dynamics Simulation; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D000072757:Protein Conformation, beta-Strand; D054730:Protein Interaction Domains and Motifs; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013816:Thermodynamics; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D012097:Repressor Proteins; C088731:Su(H) protein, Drosophila; D014157:Transcription Factors; C076560:H protein, Drosophila; D004247:DNA