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RAG1/2-mediated resolution of transposition intermediates: two pathways and possible consequences.
1Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Cell
|July 13, 2000
Summary
The RAG1/RAG2 protein complex resolves DNA intermediates through two pathways: hairpin formation leading to translocations or disintegration. Disintegration is favored in mammalian cells, potentially limiting RAG1/2 transposition frequency.
Area of Science:
- Molecular Biology
- Immunology
- Genetics
Background:
- The RAG1/RAG2 complex is crucial for V(D)J recombination in B and T cell development.
- RAG1/2 can mediate transpositional strand transfer, forming branched DNA intermediates.
Purpose of the Study:
- To investigate the resolution pathways of RAG1/2-mediated DNA intermediates.
- To understand how these pathways influence RAG1/2 activity in cellular environments.
Main Methods:
- Biochemical assays to analyze DNA intermediate resolution.
- Enzyme activity assays under varying magnesium concentrations.
Main Results:
- RAG1/2 resolves branched DNA intermediates via two distinct pathways: hairpin formation and disintegration.
- Hairpin formation on target DNA can lead to chromosome translocations.
- Disintegration removes transposed donor DNA from the intermediate.
- High magnesium concentrations, mimicking mammalian cells, favor the disintegration pathway.
Conclusions:
- RAG1/2-mediated DNA intermediate resolution is complex, involving pathways with different outcomes.
- The preference for disintegration at physiological magnesium levels may explain the low frequency of RAG1/2 transposition in cells.
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