Interactions between the R2R3-MYB transcription factor, AtMYB61, and target DNA binding sites

PLoS One. 2013 May 31;8(5):e65132. doi: 10.1371/journal.pone.0065132. Print 2013.

Abstract

Despite the prominent roles played by R2R3-MYB transcription factors in the regulation of plant gene expression, little is known about the details of how these proteins interact with their DNA targets. For example, while Arabidopsis thaliana R2R3-MYB protein AtMYB61 is known to alter transcript abundance of a specific set of target genes, little is known about the specific DNA sequences to which AtMYB61 binds. To address this gap in knowledge, DNA sequences bound by AtMYB61 were identified using cyclic amplification and selection of targets (CASTing). The DNA targets identified using this approach corresponded to AC elements, sequences enriched in adenosine and cytosine nucleotides. The preferred target sequence that bound with the greatest affinity to AtMYB61 recombinant protein was ACCTAC, the AC-I element. Mutational analyses based on the AC-I element showed that ACC nucleotides in the AC-I element served as the core recognition motif, critical for AtMYB61 binding. Molecular modelling predicted interactions between AtMYB61 amino acid residues and corresponding nucleotides in the DNA targets. The affinity between AtMYB61 and specific target DNA sequences did not correlate with AtMYB61-driven transcriptional activation with each of the target sequences. CASTing-selected motifs were found in the regulatory regions of genes previously shown to be regulated by AtMYB61. Taken together, these findings are consistent with the hypothesis that AtMYB61 regulates transcription from specific cis-acting AC elements in vivo. The results shed light on the specifics of DNA binding by an important family of plant-specific transcriptional regulators.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / metabolism*
  • Base Sequence
  • Binding Sites*
  • Consensus Sequence
  • DNA / chemistry
  • DNA / metabolism*
  • Models, Molecular
  • Nucleic Acid Conformation
  • Nucleotide Motifs
  • Position-Specific Scoring Matrices
  • Promoter Regions, Genetic
  • Protein Binding
  • Protein Conformation
  • Sequence Alignment
  • Transcription Factors / chemistry
  • Transcription Factors / metabolism*
  • Transcriptional Activation

Substances

  • Arabidopsis Proteins
  • BOTRYTIS SUSCEPTIBLE1 protein, Arabidopsis
  • MYB61 protein, Arabidopsis
  • Transcription Factors
  • DNA

Grants and funding

This work was generously supported by a Natural Science and Engineering Research Council of Canada (NSERC) Canadian Graduate Scholarship (CGSD) awarded to MBP, and funding from NSERC to MMC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.