RecA-ssDNA interaction: Induced strand cleavage by hydroxyl radical at a defined distance from the 5′ end
✍ Scribed by Akaboshi, Eiko ;Howard-Flanders, Paul
- Book ID
- 104752681
- Publisher
- Springer
- Year
- 1990
- Tongue
- English
- Weight
- 894 KB
- Volume
- 220
- Category
- Article
- ISSN
- 0026-8925
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✦ Synopsis
Interaction of the RecA protein with singlestranded DNA (ssDNA) was analyzed by challenge with the hydroxyl radical, which can cleave the D N A backbone. We found that RecA protein induces cleavage by the radical at a defined distance from the 5' end. The cleavage was at the l lth nucleotide in many oligodeoxynucleotides. Cleavage may be intermittent since a second cleavage was induced at the 22nd or 21st site. This specific cleavage was observed under optimal conditions for filament formation, homologous pairing and strand exchange. Specificity in cleavage was, however, decreased by replacement of ATP by adenosine 5'-(?,-thio)triphosphate (ATPTS), replacement of RecA protein by a mutant (RecAl) protein, or an increase in Mg 2+ concentration. We propose that RecA protein induces a special structural alteration, such as bending, perhaps sequentially, on ssDNA and that this altered site plays an important role in homologous pairing and strand exchange.