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In Vitro SUMOylation Assay to Study SUMO E3 Ligase Activity
Published on: January 29, 2018
SUMO-targeted ubiquitin ligases in genome stability
John Prudden1, Stephanie Pebernard, Grazia Raffa
1Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
The EMBO Journal
|September 1, 2007
Summary
SUMO-Targeted Ubiquitin Ligases (STUbLs) selectively ubiquitinate sumoylated proteins, maintaining pathway balance. These conserved proteins link sumoylation and ubiquitination, impacting genomic stability and DNA repair.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- The sumoylation and ubiquitination pathways are crucial for cellular regulation.
- A gap exists in understanding how these two pathways communicate and are coordinated.
- SUMO-Interacting Motifs (SIMs) are known to mediate protein-protein interactions.
Purpose of the Study:
- To identify and characterize a novel family of proteins, SUMO-Targeted Ubiquitin Ligases (STUbLs).
- To elucidate the mechanism by which STUbLs regulate sumoylated proteins.
- To investigate the functional and evolutionary conservation of STUbLs.
Main Methods:
- Protein identification and characterization.
- Yeast genetics and phenotyping (genomic instability, genotoxic stress sensitivity).
- Functional complementation assays using homologous proteins (e.g., human RNF4 in yeast).
Main Results:
- Identified the STUbL protein family, characterized by tandem SIMs, which bind sumoylated proteins or proteins with SUMO-like domains (SLDs).
- Demonstrated that STUbLs mediate ubiquitination, promoting desumoylation or degradation to maintain sumoylation homeostasis.
- Observed that loss of STUbL function leads to accumulation of sumoylated proteins, genomic instability, and stress sensitivity, phenotypes rescued by expressing human RNF4.
Conclusions:
- STUbLs represent a novel link between the sumoylation and ubiquitination pathways.
- STUbLs are essential for maintaining sumoylation pathway homeostasis and genomic integrity.
- STUbLs are evolutionarily conserved, with conserved function across species, highlighting their fundamental biological role.
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