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Updated: May 6, 2026

In Vitro SUMOylation Assay to Study SUMO E3 Ligase Activity
Published on: January 29, 2018
FLC-mediated flowering repression is positively regulated by sumoylation.
Ga Hyun Son1, Bong Soo Park, Jong Tae Song
1Department of Plant Science, Research Institute for Agriculture and Life Sciences, and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-921, Korea.
Flowering locus C (FLC) protein stability, crucial for plant reproduction, is regulated by small ubiquitin-like modifier (SUMO) conjugation. The E3 SUMO ligase AtSIZ1 stabilizes FLC, impacting flowering time.
Area of Science:
- Plant Biology
- Molecular Biology
- Genetics
Background:
- Flowering locus C (FLC) acts as a floral repressor, controlling the transition to flowering in plants.
- Understanding FLC regulation is key to controlling plant reproductive timing.
Purpose of the Study:
- To investigate the mechanisms governing Flowering locus C (FLC) protein activity and stability.
- To elucidate the role of small ubiquitin-like modifier (SUMO) conjugation in FLC regulation.
Main Methods:
- Bimolecular fluorescence complementation (BiFC) and in vitro pull-down assays to detect protein interactions.
- In vitro sumoylation assays to assess FLC modification.
- Transgenic plant studies with inducible AtSIZ1 overexpression and FLC mutant expression.
Main Results:
- FLC interacts with the E3 SUMO ligase AtSIZ1.
- AtSIZ1 binding inhibits FLC sumoylation but stabilizes FLC protein levels.
- Sumoylation of FLC is critical for its function in flowering time control.
- AtSIZ1 positively regulates FLC-mediated floral repression.
Conclusions:
- Sumoylation is a critical regulatory mechanism for FLC's role in flowering time.
- AtSIZ1 stabilizes FLC, thereby promoting floral repression and delaying flowering.
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