SUMO E3 ligase AtMMS21-dependent SUMOylation of AUXIN/INDOLE-3-ACETIC ACID 17 regulates auxin signaling

Abstract

Changes in plant auxin levels can be perceived and converted into cellular responses by auxin signal transduction. AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) proteins are auxin transcriptional inhibitors that play important roles in regulating auxin signal transduction. The stability of Aux/IAA proteins is important for transcription initiation and downstream auxin-related gene expression. Here, we report that the Aux/IAA protein IAA17 interacts with the small ubiquitin-related modifier (SUMO) E3 ligase METHYL METHANESULFONATE-SENSITIVE 21 (AtMMS21) in Arabidopsis (Arabidopsis thaliana). AtMMS21 regulated the SUMOylation of IAA17 at the K41 site. Notably, root length was suppressed in plants overexpressing IAA17, whereas the roots of K41-mutated IAA17 transgenic plants were not significantly different from wild-type roots. Biochemical data indicated that K41-mutated IAA17 or IAA17 in the AtMMS21 knock-out mutant was more likely to be degraded compared to non-mutated IAA17 in wild-type plants. In conclusion, our data revealed a role for SUMOylation in the maintenance of IAA17 protein stability, which contributes to improving our understanding of the mechanisms of auxin signaling.

Phenotypic Investigation and RNA-seq of KN1 Involved in Leaf Angle Formation in Maize (Zea mays L.)

“…By analyzing DEGs produced by B73 and kn1 under different exogenous phytohormones, we found that the genes encoding Aux/IAA, GA 3-oxidase (GA3ox), flavone synthetase (FNS), dihydroflavonol-4-reductase (DFR), xyloglucan endotransglucosylase/hydrolase (XTH), polygalacturonase inhibitor (PGI) showed different differentially expressed trends in B73 and kn1 ( Table S4 ). Aux/IAA is an important regulator of IAA signal transduction and usually forms a dimer with ARF, which has the function of TF, to inhibit the expression of related downstream genes [ 53 ]. GA3ox is a key member of GAs biosynthesis in plants, which catalyzes the production of GA 1 and GA 4 to increase the content of bioactive GAs in plants [ 54 ].…”

Genome-wide identification and expression pattern analysis of the Aux/IAA (auxin/indole-3-acetic acid) gene family in alfalfa (Medicago sativa) and the potential functions under drought stress

“…The subcellular localization prediction of the 41 MsIAA proteins revealed that most of the MsIAA proteins (MsIAA1, 3, 5, 7, 13-23, 25-28, 30, 31, 33-35, 38) were located in the nucleus, while the other 9 proteins (MsIAA4, 6,8,10,12,29,36,40,41) were located in the chloroplast, 6 proteins (2,9,11,32,37,39) were located in the cytoplasm, and only the MsIAA24 was located in the extracellular matrix (Table S3). Addition to, the results of signal peptide analysis showed that all MsIAA proteins have no peptides and signal peptides.…”

“…Detailed explanations of Aux/IAA molecular mechanisms have been obtained in plant model systems, particularly in Arabidopsis thaliana and rice (Oryza sativa) [5]. Once auxin concentration is elevated and the auxin receptor receives an auxin signal, Aux/IAA proteins will degraded by the 26S proteasome, thereby activating ARF transcriptional activity and initiating the downstream auxin response gene-cascade expression [6][7][8][9]. Therefore, precise regulation of plant growth and development processes by Aux/IAA is achieved by finely transforming the spatiotemporal dynamics of auxin levels into gene reprogramming signals.…”