639 / 2019-04-28 19:40:43

The molecular mechanism of PTRE1 in auxin - mediated regulation of proteasome activity

auxin; proteasome; PTRE1; PIP1

Plant Hormones > Plant Hormones

As an important plant hormone, auxin regulates multiple developmental processes. After binding with auxin, nuclear receptor F-box protein TIR1 (Transport Inhibitor Response 1) regulates the transcriptions of auxin-dependent genes by stimulating the ubiquitin-proteasome degradation of Aux/IAA proteins, indicating a critical role of proteasome in regulating Aux/IAA homoeostasis and auxin effects. However, whether auxin affects proteasome activity and how auxin-mediated regulation of proteasome activity regulates plant development remains unclear. Our previous studies identified and functionally characterized the PROTEASOME REGULATOR1 (PTRE1) and showed that auxin can suppress proteasome activity via PTRE1. Loss of function ptre1 mutant displayed auxin-related phenotypes. However, the molecular mechanism how auxin suppresses proteasome activity via PTRE1 is unclear, although it has been shown that auxin stimulates PTRE1 accumulation at the plasma membrane. Through phenotypic screening and bioinformatics prediction, we speculated that PIP1 (PTRE1-interacting protein1) may be involved in the auxin-mediated regulation of PTRE1 subcellular localization. Yeast hybrid and BiFC experiments preliminarily showed that PIP1 can interact with PTRE1 and both loss of function mutants of ptre1 and pip1 present similar phenotypes under high temperature treatment. Further biochemical and genetic analyses will help to elucidate the relevant mechanisms, which will be presented.