Scientists at Tokyo Metropolitan University have uncovered the mechanism of DNA regeneration, which occurs through homologous recombination involving the RecA protein. The findings, published in the journal Nucleic Acids Research, will help identify factors that disrupt this process and lead to diseases such as breast cancer.
Homologous recombination is the most widely used way for cells to repair damaged DNA that has a break in one or both strands. In this process, an undamaged copy of DNA located in a homologous chromosome is used for repair. First, one of the broken ends is removed (resected), and then the RecA protein reinserts the dangling part of the chain into another chromosome, after which the lost part of the chain is completed. In doing so, the chromosomes can also exchange genetic material.
The researchers tested two different models of how homologous recombination occurs involving RecA. In one, RecA unwinds a section of the intact double strand while searching for a suitable site to insert the end of the damaged strand. In the second, unwinding occurs only when the incorporation has already occurred.
