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Recombination activating gene 1 product alone possesses endonucleolytic activity
1Department of Biochemistry, College of Medicine, Gyeongsang National University, 92 Chilam-dong, Jinju 660-751, Korea. drkim@nongae.gsnu.ac.kr
Journal of Biochemistry and Molecular Biology
|April 12, 2003
Summary
The RAG1 protein alone exhibits a unique nicking activity on DNA substrates, separate from its role in V(D)J recombination. This distinct endonucleolytic function of RAG1 may play a novel role in immune system development.
Area of Science:
- Molecular Biology
- Immunology
- Biochemistry
Background:
- V(D)J recombination is a crucial process for adaptive immunity, requiring lymphoid-specific proteins RAG1 and RAG2.
- RAG proteins mediate DNA cleavage, forming hairpins at coding ends and double-strand breaks at signal ends during V(D)J recombination.
Purpose of the Study:
- To investigate the individual enzymatic activities of RAG1 beyond its known role in V(D)J recombination.
- To characterize a distinct endonucleolytic activity of RAG1.
Main Methods:
- In vitro assays using purified RAG1 protein and a tethered oligonucleotide substrate.
- Analysis of RAG1 mutants' endonucleolytic activity.
- Immunoprecipitation using RAG1-specific antibodies.
Main Results:
- Purified RAG1 protein alone demonstrated a specific nicking activity on a tethered DNA substrate near the recombination signal sequence.
- This nicking activity was dependent on the 3'-hydroxy group and was abolished by RAG1-specific antibody.
- RAG1 mutants defective in V(D)J cleavage also exhibited this novel endonucleolytic activity.
Conclusions:
- RAG1 possesses an intrinsic endonucleolytic activity independent of RAG2.
- This newly identified nicking activity of RAG1 may represent a distinct function separate from its role in V(D)J hairpin formation.