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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

Transcript levels of flowering-related genes in hpy2-2 mutants. Total RNA was isolated from the leaves of WT and hpy2-2 mutant plants grown in soil under long (A)-or short-day (B) conditions. Transcript levels were examined using real-time qRT-PCR with gene-specific primers. Results are expressed as the mean ± SD (n = 3). FLC, FLOWERING LOCUS C; SOC1, SUPPRESSOR OF OVEREXPRESSION OF CO 1; FT, FLOWERING LOCUS T; TSF, TWIN SISTER OF FT.
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Figure 5: Transcript levels of flowering-related genes in hpy2-2 mutants. Total RNA was isolated from the leaves of WT and hpy2-2 mutant plants grown in soil under long (A)-or short-day (B) conditions. Transcript levels were examined using real-time qRT-PCR with gene-specific primers. Results are expressed as the mean ± SD (n = 3). FLC, FLOWERING LOCUS C; SOC1, SUPPRESSOR OF OVEREXPRESSION OF CO 1; FT, FLOWERING LOCUS T; TSF, TWIN SISTER OF FT.

Mentions: HPY2 was identified as an E3 SUMO ligase for FLC, suggesting that the early flowering phenotype seen in hpy2-2 mutants might be partly caused by low levels of FLC and decreased FLC activity. However, it was also possible that early flowering in hpy2-2 mutants occurred as a consequence of altered gene expression. To investigate this, real-time qRT-PCR was used to measure transcript levels of FLC and the flowering-related genes SOC1, FT, and TSF in WT and hpy2-2 mutants grown in long- or short-day conditions (Figures 5A,B). SOC1, FT, and TSF were slightly upregulated in hpy2-2 mutants compared with their expression in WT plants under long-day conditions (Figure 5A). More substantial differences in the expression of SOC1, FT, and TSF were apparent under short-day conditions, with approximately twofold higher transcript levels observed in hpy2-2 plants compared to WT plants (Figure 5B).


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)

Transcript levels of flowering-related genes in hpy2-2 mutants. Total RNA was isolated from the leaves of WT and hpy2-2 mutant plants grown in soil under long (A)-or short-day (B) conditions. Transcript levels were examined using real-time qRT-PCR with gene-specific primers. Results are expressed as the mean ± SD (n = 3). FLC, FLOWERING LOCUS C; SOC1, SUPPRESSOR OF OVEREXPRESSION OF CO 1; FT, FLOWERING LOCUS T; TSF, TWIN SISTER OF FT.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4837325&req=5

Figure 5: Transcript levels of flowering-related genes in hpy2-2 mutants. Total RNA was isolated from the leaves of WT and hpy2-2 mutant plants grown in soil under long (A)-or short-day (B) conditions. Transcript levels were examined using real-time qRT-PCR with gene-specific primers. Results are expressed as the mean ± SD (n = 3). FLC, FLOWERING LOCUS C; SOC1, SUPPRESSOR OF OVEREXPRESSION OF CO 1; FT, FLOWERING LOCUS T; TSF, TWIN SISTER OF FT.
Mentions: HPY2 was identified as an E3 SUMO ligase for FLC, suggesting that the early flowering phenotype seen in hpy2-2 mutants might be partly caused by low levels of FLC and decreased FLC activity. However, it was also possible that early flowering in hpy2-2 mutants occurred as a consequence of altered gene expression. To investigate this, real-time qRT-PCR was used to measure transcript levels of FLC and the flowering-related genes SOC1, FT, and TSF in WT and hpy2-2 mutants grown in long- or short-day conditions (Figures 5A,B). SOC1, FT, and TSF were slightly upregulated in hpy2-2 mutants compared with their expression in WT plants under long-day conditions (Figure 5A). More substantial differences in the expression of SOC1, FT, and TSF were apparent under short-day conditions, with approximately twofold higher transcript levels observed in hpy2-2 plants compared to WT plants (Figure 5B).

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