Biochemical characterization of recombinant polypeptides corresponding to the predicted betaalphaalpha fold in Aux/IAA proteins

FEBS Lett. 1999 Jul 9;454(3):283-7. doi: 10.1016/s0014-5793(99)00819-4.

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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis
  • Circular Dichroism
  • Indoleacetic Acids / chemistry*
  • Indoleacetic Acids / metabolism*
  • Molecular Sequence Data
  • Peptides / chemistry
  • Peptides / metabolism
  • Protein Folding*
  • Protein Structure, Secondary
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Sequence Alignment

Substances

  • Indoleacetic Acids
  • Peptides
  • Recombinant Proteins