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Multiple forms of formamidopyrimidine-DNA glycosylase produced by alternative splicing in Arabidopsis thaliana

Terence M. Murphy1 and Ming-Jun Gao2

Section of Plant Biology, University of California, One Shields Ave., Davis, CA 95616 USA


Formamidopyrimidine-DNA glycosylase (FPG) catalyzes the initial steps in the repair of DNA containing oxidized purines. Two cDNA clones from Arabidopsis thaliana encoding homologs of bacterial FPG have previously been described. We now report that there are at least five additional variants of FPG mRNA in Arabidopsis, each apparently produced from the same gene (AtMMH) by alternative splicing. Thus, AtMMH, like at least four other genes in the base excision repair pathway of human cells, produces multiple forms of protein product through alternative splicing. The variant forms of Arabidopsis FPG may be localized in different locations in the cells, may have different preferences for oxidized substrates, and/or may recruit different proteins that guide the subsequent steps of base excision repair.






1Correspondence to: Terence M. Murphy, Section of Plant Biology, One Shields Avenue, University of California, Davis, CA 95616; FAX +1 (530) 752-5410; e-mail

2Present address: Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5 Canada

Abbreviations: fapy-A, 4,6-diamino-5-formamidopyrimidine; fapy-G, 2,6-diamino-4-hydroxy-5-formamidopyrimidine; FPG, formamidopyrimidine-DNA glycosylase; 8-oxo-G, 7,8-dihydro-8-oxoguanine.

The background image in this paper is a representation of human 8-oxo-G glycosylase (Bruner et al., 2000). This enzyme has an activity similar, but is not homologous, to FPG.