Architecture of DNA elements mediating ARF transcription factor binding and auxin-responsive gene expression in Arabidopsis

Alejandra Freire-Rios, Keita Tanaka, Isidro Crespo, Elmar Van der Wijk, Yana Sizentsova, Victor Levitsky, Simon Lindhoud, Mattia Fontana, Johannes Hohlbein, D.R. Boer, Victoria Mironova, Dolf Weijers*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The hormone auxin controls many aspects of the plant life cycle by regulating the expression of thousands of genes. The transcriptional output of the nuclear auxin signaling pathway is determined by the activity of AUXIN RESPONSE transcription FACTORs (ARFs), through their binding to cis-regulatory elements in auxinresponsive genes. Crystal structures, in vitro, and heterologous studies have fueled a model in which ARF dimers bind with high affinity to distinctly spaced repeats of canonical AuxRE motifs. However, the relevance of this "caliper" model, and the mechanisms underlying the binding affinities in vivo, have remained elusive. Here we biochemically and functionally interrogate modes of ARF-DNA interaction. We show that a single additional hydrogen bond in Arabidopsis ARF1 confers high-affinity binding to individual DNA sites. We demonstrate the importance of AuxRE cooperativity within repeats in the Arabidopsis TMO5 and IAA11 promoters in vivo. Meta-analysis of transcriptomes further reveals strong genome-wide association of auxin response with both inverted (IR) and direct (DR) AuxRE repeats, which we experimentally validated. The association of these elements with auxininduced up-regulation (DR and IR) or down-regulation (IR) was correlated with differential binding affinities of A-class and B-class ARFs, respectively, suggesting a mechanistic basis for the distinct activity of these repeats. Our results support the relevance of highaffinity binding of ARF transcription factors to uniquely spaced DNA elements in vivo, and suggest that differential binding affinities of ARF subfamilies underlie diversity in cis-element function.

Original languageEnglish
Pages (from-to)24557-24566
Number of pages10
JournalProceedings of the National Academy of Sciences of the United States of America
Volume117
Issue number39
DOIs
Publication statusPublished - 29 Sep 2020

Keywords

  • ARF transcription factors
  • Auxin
  • Plant biology
  • Protein-DNA interaction
  • Transcriptional regulation

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