title: Arabidopsis HIGH PLOIDY2 Sumoylates and Stabilizes Flowering Locus C through Its E3 Ligase Activity.
abstract: Flowering Locus C (FLC), a floral repressor, plays an important role in flowering. The mechanisms regulating FLC gene expression and protein function have been studied extensively; however, post-translational regulation of FLC remains unclear. Here, we identified Arabidopsis HIGH PLOIDY2 (HPY2) as an E3 SUMO ligase for FLC. In vitro and vivo pull-down assays showed that FLC physically interacts with HPY2. In vitro assays showed that the stimulation of FLC sumoylation by HPY2 was dependent on SUMO-activating enzyme E1 and -conjugating enzyme E2, indicating that HPY2 was an E3 SUMO ligase for FLC. In transgenic plants, inducible HPY2 overexpression increased the concentration of FLC, indicating that HPY2 stabilized FLC through direct sumoylation. Flowering time in hpy2-2 mutants was shorter than in wild-type plants under long- and short-day conditions, with a greater effect under short-day conditions, and FLC was downregulated in hpy2-2 mutants. These data indicate that HPY2 regulates FLC function and stability at both the transcriptional and post-translational levels through its E3 SUMO ligase activity.
authors.affiliation: Department of Plant Science and Research Institute of Agriculture and Life Sciences, Seoul National University Seoul, South Korea.
authors.forename: Jun S
authors.initials: JS
authors.lastname: Kwak
authors.affiliation: Department of Plant Science and Research Institute of Agriculture and Life Sciences, Seoul National University Seoul, South Korea.
authors.forename: Ga H
authors.initials: GH
authors.lastname: Son
authors.affiliation: Department of Plant Science and Research Institute of Agriculture and Life Sciences, Seoul National University Seoul, South Korea.
authors.forename: Sung-Il
authors.initials: SI
authors.lastname: Kim
authors.affiliation: School of Applied Biosciences, Kyungpook National University Daegu, South Korea.
authors.forename: Jong T
authors.initials: JT
authors.lastname: Song
authors.affiliation: Department of Plant Science and Research Institute of Agriculture and Life Sciences, Seoul National UniversitySeoul, South Korea; Plant Genomics and Breeding Institute, Seoul National UniversitySeoul, South Korea; Bio-MAX Institute Seoul National UniversitySeoul, South Korea.
authors.forename: Hak S
authors.initials: HS
authors.lastname: Seo
keywords: E3 SUMO ligase; FLC; HPY2; SUMO; post-translational modification; sumoylation