Direct ETTIN-auxin interaction controls chromatin states in gynoecium development

• Published in: eLife Vol. 9
• Main Authors: Kuhn, André, Ramans Harborough, Sigurd, McLaughlin, Heather M, Natarajan, Bhavani, Verstraeten, Inge, Friml, Jiří, Kepinski, Stefan, Østergaard, Lars
• Format: Journal Article
• Language: English
• Published: England eLife Sciences Publications Ltd 08.04.2020; eLife Sciences Publications, Ltd
• Subjects: Acetylation; Amino acids; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Auxin; Chromatin; Chromatin - chemistry; Chromatin - metabolism; Developmental Biology; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; ETTIN; Experiments; Flowers - genetics; Flowers - growth & development; Flowers - metabolism; Gene expression; Gene regulation; gynoecium development; histone modification; Indoleacetic acid; Indoleacetic Acids - chemistry; Indoleacetic Acids - metabolism; Ligands; NMR; Nuclear magnetic resonance; Plant Biology; Proteins; Repressors; Signal Transduction - genetics; Transcription factors; Chromatin; Auxin; histone modification; A. thaliana; developmental biology; ETTIN; plant biology; gynoecium development; gene expression
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/elife.51787

Hormonal signalling in animals often involves direct transcription factor-hormone interactions that modulate gene expression. In contrast, plant hormone signalling is most commonly based on de-repression via the degradation of transcriptional repressors. Recently, we uncovered a non-canonical signalling mechanism for the plant hormone auxin whereby auxin directly affects the activity of the atypical auxin response factor (ARF), ETTIN towards target genes without the requirement for protein degradation. Here we show that ETTIN directly binds auxin, leading to dissociation from co-repressor proteins of the TOPLESS/TOPLESS-RELATED family followed by histone acetylation and induction of gene expression. This mechanism is reminiscent of animal hormone signalling as it affects the activity towards regulation of target genes and provides the first example of a DNA-bound hormone receptor in plants. Whilst auxin affects canonical ARFs indirectly by facilitating degradation of Aux/IAA repressors, direct ETTIN-auxin interactions allow switching between repressive and de-repressive chromatin states in an instantly-reversible manner.