TOBACCO BY-2 CELLS EXCISE BOTH 3-METHYLADENINE AND 7-METHYLGUANINE FROM METHYLATED DNA

Two of the major products in DNA resulting from exposure to alkylating agents are 7-methylguanine and 3-methyladenine. N-methylpurine-DNA-gl ycosylase is required for excision of these lesions. Recently, the 3-m ethyladenine-DNA-glycosylase gene of Arabidopsis thaliana was cloned a nd shown to be involved only in repair of 3-methyladenine. In BY-2 tob acco cells, we showed an enzymatic activity which excised both 3-methy ladenine and 7-methylguanine from methylated DNA. (C) 1998 Elsevier Sc ience B.V. All rights reserved.