XVI International Botanical Congess

Two clones encoding homologs of bacterial FaPy-DNA glycosylase were previously isolated and named Atfpg-1 and Atfpg-2 (Murphy and Gao, 1998, Plant Physiol. 118:1535). In this study, Southern analysis with a probe representing identical nucleotides of the two clones indicates that there are 2-3 genes sharing the common sequence. DNA blots hybridized with Atfpg-1-specific and Atfpg-2-specific probes confirm that both mRNAs come from one of these genes. Northern analysis demonstrated that the expressions of the two clones are different and organ-specific. It was also found that RNA blots using specific probes hybridized with substantial amounts of RNA of large length, suggesting that processing of transcripts is a limiting step in the productions of the two kinds of mRNAs. Fusion vector for overexpression was constructed, recombinant protein expressed by Atfpg-2 clone was purified, and activity of the protein in DNA repair was assayed. In addition to showing a preference for V-C irradiated DNA, the protein preferentially cleaves DNA that contains apurinic sites, indicating this kind of protein acts as an enzyme and is involved in the excision repair of damaged DNA.