{Reference Type}: Journal Article
{Title}: A dose-dependent bimodal switch by homologous Aux/IAA transcriptional repressors.
{Author}: Cho HT;Lee M;Choi HS;Maeng KH;Lee K;Lee HY;Ganguly A;Park H;Ho CH;
{Journal}: Mol Plant
{Volume}: 17
{Issue}: 9
{Year}: 2024 Sep 2
{Factor}: 21.949
{DOI}: 10.1016/j.molp.2024.07.014
{Abstract}: Combinatorial interactions between different regulators diversify and enrich the chance of transcriptional regulation in eukaryotic cells. However, a dose-dependent functional switch of homologous transcriptional repressors has rarely been reported. Here, we show that SHY2, an auxin/indole-3-acetic acid (Aux/IAA) repressor, exhibits a dose-dependent bimodal role in auxin-sensitive root-hair growth and gene transcription in Arabidopsis, whereas other Aux/IAA homologs consistently repress the auxin responses. The co-repressor (TOPLESS [TPL])-binding affinity of a bimodal Aux/IAA was lower than that of a consistently repressing Aux/IAA. The switch of a single amino acid residue in the TPL-binding motif between the bimodal form and the consistently repressing form switched their TPL-binding affinity and transcriptional and biological roles in auxin responses. Based on these data, we propose a model whereby competition between homologous repressors with different co-repressor-binding affinities could generate a bimodal output at the transcriptional and developmental levels.