Base Replacement Mechanisms for the Repair of Unnatural and Damaged Bases in DNA
Part of the
NATO Advanced Study Institutes Series
book series (NSSA, volume 40)
A purine insertase activity was found in extracts from E. coli H502. This activity brings about the insertion of adenine and of guanine into the appropriate apurinic sites in DNA, using dATP and dGTP as the purine donors, in a Mg++-dependnet reaction. Using extracts prepared from E. coli strains KMBL 1719 and 1720 we found a Mg++-dependent insertion of the free purine bases into depurinated DNA. It is possible that induced functions are involved in the process of insertion since active extracts could be prepared from E. coli strains (including AB3027 ap endo-poll-) only if they were grown in the presence of sublethal doses of alkylating agents.
A new method was developed for assaying base replacement mechanisms, based on the use of DNA with labeled AP sites. This method is currently used to look for a pyrimidine insertase activity in E. coli.
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© Plenum Press, New York 1981