title: Biochemical characterization of recombinant polypeptides corresponding to the predicted betaalphaalpha fold in Aux/IAA proteins.
abstract: The plant hormone indoleacetic acid (IAA or auxin) transcriptionally activates a select set of early genes. The Aux/IAA class of early auxin-responsive genes encodes a large family of short-lived, nuclear proteins. Aux/IAA polypeptides homo- and heterodimerize, and interact with auxin-response transcription factors (ARFs) via C-terminal regions conserved in both protein families. This shared region contains a predicted betaalphaalpha motif similar to the prokaryotic beta-ribbon DNA binding domain, which mediates both protein dimerization and DNA recognition. Here, we show by circular dichroism spectroscopy and by chemical cross-linking experiments that recombinant peptides corresponding to the predicted betaalphaalpha region of three Aux/IAA proteins from Arabidopsis thaliana contain substantial alpha-helical secondary structure and undergo homo- and heterotypic interactions in vitro. Our results indicate a similar biochemical function of the plant betaalphaalpha domain and suggest that the betaalphaalpha fold plays an important role in mediating combinatorial interactions of Aux/IAA and ARF proteins to specifically regulate secondary gene expression in response to auxin.
authors.affiliation: Department of Vegetable Crops, University of California-Davis, 95616, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Morgan
authors.forename: T I
authors.initials: TI
authors.lastname: Zarembinski
authors.forename: A
authors.initials: A
authors.lastname: Theologis
authors.forename: S
authors.initials: S
authors.lastname: Abel
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis; D002942:Circular Dichroism; D007210:Indoleacetic Acids / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D007210:Indoleacetic Acids; D010455:Peptides; D011994:Recombinant Proteins