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Structural basis for oligomerization of auxin transcriptional regulators

2014; Nature Portfolio; Volume: 5; Issue: 1 Linguagem: Inglês

10.1038/ncomms4617

2041-1723

Max Nanao, Thomas Vinos-Poyo, Géraldine Brunoud, Emmanuel Thévenon, Meryl Mazzoleni, David Mast, Stéphanie Lainé, Shucai Wang, Gretchen Hagen, Hanbing Li, Thomas J. Guilfoyle, François Parcy, Teva Vernoux, Renaud Dumas,

Plant Gene Expression Analysis

The plant hormone auxin is a key morphogenetic regulator acting from embryogenesis onwards. Transcriptional events in response to auxin are mediated by the auxin response factor (ARF) transcription factors and the Aux/IAA (IAA) transcriptional repressors. At low auxin concentrations, IAA repressors associate with ARF proteins and recruit corepressors that prevent auxin-induced gene expression. At higher auxin concentrations, IAAs are degraded and ARFs become free to regulate auxin-responsive genes. The interaction between ARFs and IAAs is thus central to auxin signalling and occurs through the highly conserved domain III/IV present in both types of proteins. Here, we report the crystal structure of ARF5 domain III/IV and reveal the molecular determinants of ARF–IAA interactions. We further provide evidence that ARFs have the potential to oligomerize, a property that could be important for gene regulation in response to auxin. The transcriptional effects of auxin signalling are mediated by auxin response factors (ARFs) that interact with inhibitory IAA proteins. Nanao et al.present the crystal structure of domain III/IV of ARF5, revealing the structural basis for its interaction with IAAs and its potential to trigger ARF5 oligomerization.