Related Experiment Videos
Transcription-dependent recombination induced by triple-helix formation
1La Jolla Cancer Research Foundation, California 92037.
Genes & Development
|September 1, 1993
Summary
Active transcription induces homologous recombination via poly(dG)-poly(dC) sequences, forming a triple helix. This RecA-independent process depends on sequence length and orientation, facilitating DNA repair.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Homologous recombination is a crucial DNA repair mechanism.
- Transcription can influence genomic recombination events.
- Poly(dG)-poly(dC) sequences are known to form unusual DNA structures.
Purpose of the Study:
- To investigate the role of poly(dG)-poly(dC) sequences in transcription-induced homologous recombination.
- To determine the mechanism by which these sequences mediate recombination.
- To explore the influence of sequence length and orientation on recombination frequency.
Main Methods:
- Induction of homologous recombination between direct repeats in Escherichia coli.
- Manipulation of poly(dG)-poly(dC) sequence length and orientation.
- Analysis of RecA dependency.
- Detection of intramolecular DNA triplex formation in vivo.
Main Results:
- Active transcription of a downstream gene induced homologous recombination between direct repeats flanking poly(dG)-poly(dC) sequences.
- Recombination was RecA-independent and dependent on the length and orientation of the poly(dG)-poly(dC) tract.
- Intramolecular dG.dG.dC triplex formation was observed in vivo in a length-dependent manner during active transcription.
Conclusions:
- Transcription-induced negative superhelical strain promotes poly(dG)-poly(dC) sequences to form triple-helix structures in vivo.
- This triplex structure facilitates the association of remote DNA sequences, thereby stimulating homologous recombination.
- Poly(dG)-poly(dC) tracts can act as regulatory elements in transcription-coupled recombination.