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.
Highlights
Much of plant growth and development is shaped by sequencespecific transcription factors, proteins that act in response to external and internal cues to modulate gene expression
R2R3-MYB proteins bind to AC elements in a manner that relies on specific amino acid residues in the R2R3-MYB domain [29,30,31,32,33]
The protocol was approved at the University of Toronto, which involved full committee review by the Local Animal Care Committee (LACC), followed by approval by the University of Toronto Office of Research Ethics, the University Veterinarian, and the University of Toronto Animal Care Committee (UACC) (Permit Number: 20007080, approved 14/01/08)
Summary
Much of plant growth and development is shaped by sequencespecific transcription factors, proteins that act in response to external and internal cues to modulate gene expression. Many R2R3-MYB transcription factors bind to DNA motifs that are enriched in adenosine (A) and cytosine (C) residues [8,17], where guanine (G) residues are either absent or depleted [16,18]. R2R3-MYB proteins bind to AC elements in a manner that relies on specific amino acid residues in the R2R3-MYB domain [29,30,31,32,33]. AtMYB61, a member of the Arabidopsis thaliana R2R3-MYB family of transcription factors, illustrates the involvement of R2R3MYB family members in the regulation of plant-specific processes. Given that R2R3-MYB proteins are involved in a rich variety of plant-specific processes [2], it would be desirable to have a more detailed understanding of R2R3-MYB and DNA motif interactions. The sequences identified served as a useful foundation to examine mechanisms responsible for AtMYB61 sequence-specific binding, and to hypotheses about the roles these may play in shaping AtMYB61 function in vivo
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
