DNA Repair Mechanism Maintains Genetic Stability

Researchers working with Escherichia coli have observed a mechanism for DNA repair that functions to correct errors remaining after primary repair and helps to maintain the genetic stability of the organism. This finding was reported in the October 2002 issue of Molecular Cell.

When primary DNA repair mechanisms fail, cell death usually prevents the incorporation of mutations into the genome. However, when gross DNA repair is successful, some areas of the genome still contain damaged areas that may lead to the propagation of mutations (usually unfavorable). The recombinational repair (RR) mechanism employed by E coli to repair this type of damaged DNA was found by researchers at the Weizmann Institute of Science (Rehovot, Israel) to operate in about 85% of the incidences of DNA damage. The alternate translesion replication (TLR) mechanism functions about 15% of the time. TLR does not completely remove all damage to the genome, as opposed to RR, which corrects all DNA damage. Thus, E coli has evolved a way to correct remaining damaged areas in a way that eliminates mutations and ensures genetic stability.

The repair mechanisms that were studied in E coli have been well preserved throughout evolution, which suggests that variants of these mechanisms exist and operate in more developed organisms, including humans. The findings reported in the current study may help to advance gene therapy of human diseases as well as to suggest ways to circumvent the rapid mutation rate of bacteria that leads to drug resistance.




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Weizmann Institute of Science