title: High-resolution structure of the HNF-1alpha dimerization domain.
abstract: The N-terminal dimerization domain of the transcriptional activator hepatocyte nuclear factor-1alpha (HNF-1alpha) is essential for DNA binding and association of the transcriptional coactivator, DCoH (dimerization cofactor of HNF-1). To investigate the basis for dimerization of HNF-1 proteins, we determined the 1.2 A resolution X-ray crystal structure of the dimerization domain of HNF-1alpha (HNF-p1). Phasing was facilitated by devising a simple synthesis for Fmoc-selenomethionine and substituting leucine residues with selenomethionine. The HNF-1 dimerization domain forms a unique, four-helix bundle that is preserved with localized conformational shifts in the DCoH complex. In three different crystal forms, HNF-p1 displays subtle shifts in the conformation of the interhelix loop and the crossing angle between the amino- and carboxyl-terminal helices. In all three crystal forms, the HNF-p1 dimers pair through an exposed hydrophobic surface that also forms the binding site for DCoH. Conserved core residues in the dimerization domain of the homologous transcriptional regulator HNF-1beta rationalize the functional heterodimerization of the HNF-1alpha and HNF-1beta proteins. Mutations in HNF-1alpha are associated with maturity-onset diabetes of the young type 3 (MODY3), and the structure of HNF-p1 provides insights into the effects of three MODY3 mutations.
authors: Department of Molecular and Cell Biology, 229 Stanley Hall #3206, University of California, Berkeley, California 94720-3206, USA.
authors: R B
authors: RB
authors: Rose
authors: J A
authors: JA
authors: Endrizzi
authors: J D
authors: JD
authors: Cronk
authors: J
authors: J
authors: Holton
authors: T
authors: T
authors: Alber
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D019281:Dimerization; D051537:Hepatocyte Nuclear Factor 1; D051538:Hepatocyte Nuclear Factor 1-alpha; D051539:Hepatocyte Nuclear Factor 1-beta; D018398:Homeodomain Proteins / Q000737:chemistry* / Q000378:metabolism; D006836:Hydro-Lyases / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012645:Selenomethionine / Q000031:analogs & derivatives; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D051538:Hepatocyte Nuclear Factor 1-alpha; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; D051537:Hepatocyte Nuclear Factor 1; D051539:Hepatocyte Nuclear Factor 1-beta; D012645:Selenomethionine; D006836:Hydro-Lyases; C076392:pterin-4a-carbinolamine dehydratase