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In vitro reconstitution of human replication factor C from its five subunits
F Uhlmann1, J Cai, H Flores-Rozas
1Program in Molecular Biology, Memorial Sloan-Kettering Cancer Center, NY 10021, USA.
Summary
Replication Factor C (RFC) is crucial for eukaryotic DNA replication, loading the PCNA clamp onto DNA. This study demonstrates that human RFC subunits can self-assemble in vitro to form an active complex, revealing insights into its assembly mechanism.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Replication Factor C (RFC) is essential for eukaryotic DNA replication, facilitating the interaction between DNA polymerases and template DNA via PCNA loading.
- Human RFC is a five-subunit complex, with all genes cloned and sequenced, showing homology to its yeast counterpart.
Purpose of the Study:
- To express the five cloned human RFC genes in vitro.
- To demonstrate the formation of a functional RFC complex from these expressed subunits.
- To investigate the subunit interactions and assembly mechanism of the human RFC complex.
Main Methods:
- In vitro coupled transcription/translation system for expressing human RFC genes.
- SDS/polyacrylamide gel electrophoresis to analyze subunit composition.
- RFC-dependent replication assays to assess complex activity.
Main Results:
- The five human RFC genes expressed in vitro formed a complex that supported RFC-dependent replication.
- A core complex of three subunits (p36, p37, p40) was identified.
- Subunit p38 was found to be essential for the interaction between the core complex and the p140 subunit.
Conclusions:
- Human RFC subunits can assemble into a functional complex in vitro, mimicking the native structure and activity.
- The findings suggest a cooperative mechanism for RFC complex assembly, with a defined core and essential interactions for full complex formation.