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Localization of SUMO-modified Proteins Using Fluorescent Sumo-trapping Proteins
Published on: April 27, 2019
Crystal structure of SUMO-modified proliferating cell nuclear antigen
Bret D Freudenthal1, John E Brogie, Lokesh Gakhar
1Department of Biochemistry, University of Iowa College of Medicine, Iowa City, IA 52242-1109, USA.
Journal of Molecular Biology
|December 21, 2010
Summary
SUMO modification regulates proliferating cell nuclear antigen (PCNA) by binding to its back face, distinct from ubiquitin. This allows PCNA to act as a regulatory tool belt for DNA replication and repair.
Area of Science:
- Molecular Biology
- Biochemistry
- Structural Biology
Background:
- Proliferating cell nuclear antigen (PCNA) is crucial for DNA replication, repair, and recombination in eukaryotes.
- Posttranslational modifications, such as ubiquitylation and sumoylation, modulate PCNA's diverse functions.
- Sumoylation inhibits recombination, while ubiquitylation promotes translesion synthesis.
Purpose of the Study:
- To elucidate the regulatory mechanism of SUMO modification on PCNA.
- To understand how SUMOylation impacts PCNA's interaction with other proteins and its function.
Main Methods:
- Generation of a split SUMO-modified PCNA protein.
- Assay of DNA polymerase δ activity.
- X-ray crystallography to determine the structure of SUMO-modified PCNA.
Main Results:
- SUMO-modified PCNA supports cell viability and enhances DNA polymerase δ activity.
- The crystal structure reveals SUMO binding on the back face of the PCNA ring.
- SUMO's binding site is distinct from the previously characterized ubiquitin binding site.
Conclusions:
- The back face of PCNA serves as a regulatory site for modifications like sumoylation.
- These modifications can occur without interfering with ongoing DNA replication on the front face.
- PCNA may function as a "tool belt," recruiting and holding proteins for DNA repair and replication machinery.
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