Submitted to: Federation of European Biochemical Societies Letters
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/1/1999
Publication Date: N/A
Citation: Theologis, A., Morgan, K.E., Zarembinski, T.I., Abel, S. 1999. Biochemical characterization of recombinant polypeptides corresponding to the preducted betaalphaalpha fold in aux/iaa proteins. Federation of European Biochemical Societies Letters, 454(3) 283-7. Interpretive Summary: Our results indicate 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.
Technical 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 predicte 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.