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Arabidopsis HIGH PLOIDY2 Sumoylates and Stabilizes Flowering Locus C through Its E3 Ligase Activity.

Kwak JS, Son GH, Kim SI, Song JT, Seo HS - Front Plant Sci (2016)

Bottom Line: Here, we identified Arabidopsis HIGH PLOIDY2 (HPY2) as 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.These data indicate that HPY2 regulates FLC function and stability at both the transcriptional and post-translational levels through its E3 SUMO ligase activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Science and Research Institute of Agriculture and Life Sciences, Seoul National University Seoul, South Korea.

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.

No MeSH data available.


Related in: MedlinePlus

Flowering time of hpy2-2 mutants. Early flowering was observed in the hpy2-2 mutant grown under both long- and short-day conditions (A). Flowering time was investigated by counting the number of rosette leaves present when inflorescences appeared (B). The number of rosettes in WT and hpy2-2 plants differed significantly (∗∗∗P < 0.0001, t-test, n = 20). Bars indicate standard errors.
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Figure 4: Flowering time of hpy2-2 mutants. Early flowering was observed in the hpy2-2 mutant grown under both long- and short-day conditions (A). Flowering time was investigated by counting the number of rosette leaves present when inflorescences appeared (B). The number of rosettes in WT and hpy2-2 plants differed significantly (∗∗∗P < 0.0001, t-test, n = 20). Bars indicate standard errors.

Mentions: Flowering Locus C is stabilized by HPY2-mediated sumoylation, suggesting that FLC functions may be compromised in a hpy2 mutant background and that flowering may be affected. Two independent T-DNA insertion mutant lines, hpy2-1 and hpy2-2, were characterized previously (Ishida et al., 2009, 2012). The hpy2-2 mutant exhibits a relatively weak phenotype, but the hpy2-1 mutant shows a severe growth defect phenotype and growth frequently stops prior to bolting. The hpy2-2 mutant was therefore chosen to examine flowering time. Rosette leaves were counted just after bolting in WT and hpy2-2 plants. Compared to WT, flowering was delayed in hpy2-2 mutants under both long- and short-day conditions (Figures 4A,B). Flowering delay in hpy2-2 was significant under short-day conditions but was less pronounced under long-day conditions (Figures 4A,B).


Arabidopsis HIGH PLOIDY2 Sumoylates and Stabilizes Flowering Locus C through Its E3 Ligase Activity.

Kwak JS, Son GH, Kim SI, Song JT, Seo HS - Front Plant Sci (2016)

Flowering time of hpy2-2 mutants. Early flowering was observed in the hpy2-2 mutant grown under both long- and short-day conditions (A). Flowering time was investigated by counting the number of rosette leaves present when inflorescences appeared (B). The number of rosettes in WT and hpy2-2 plants differed significantly (∗∗∗P < 0.0001, t-test, n = 20). Bars indicate standard errors.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837325&req=5

Figure 4: Flowering time of hpy2-2 mutants. Early flowering was observed in the hpy2-2 mutant grown under both long- and short-day conditions (A). Flowering time was investigated by counting the number of rosette leaves present when inflorescences appeared (B). The number of rosettes in WT and hpy2-2 plants differed significantly (∗∗∗P < 0.0001, t-test, n = 20). Bars indicate standard errors.
Mentions: Flowering Locus C is stabilized by HPY2-mediated sumoylation, suggesting that FLC functions may be compromised in a hpy2 mutant background and that flowering may be affected. Two independent T-DNA insertion mutant lines, hpy2-1 and hpy2-2, were characterized previously (Ishida et al., 2009, 2012). The hpy2-2 mutant exhibits a relatively weak phenotype, but the hpy2-1 mutant shows a severe growth defect phenotype and growth frequently stops prior to bolting. The hpy2-2 mutant was therefore chosen to examine flowering time. Rosette leaves were counted just after bolting in WT and hpy2-2 plants. Compared to WT, flowering was delayed in hpy2-2 mutants under both long- and short-day conditions (Figures 4A,B). Flowering delay in hpy2-2 was significant under short-day conditions but was less pronounced under long-day conditions (Figures 4A,B).

Bottom Line: Here, we identified Arabidopsis HIGH PLOIDY2 (HPY2) as 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.These data indicate that HPY2 regulates FLC function and stability at both the transcriptional and post-translational levels through its E3 SUMO ligase activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Science and Research Institute of Agriculture and Life Sciences, Seoul National University Seoul, South Korea.

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.

No MeSH data available.


Related in: MedlinePlus