3-Methyladenine DNA glycosylases: structure, function, and biological importance

The genome-continuously suffers damage due to its reactivity with chemical and physical agents. Finding such damage in genomes (that can be several mi llion to several billion nucleotide base pairs in size) is a seemingly daun ting task, 3-Methyladenine DNA glycosylases can initiate the base excision repair (BER) of an extraordinarily wide-range of substrate bases. The advan tage of such broad substrate recognition is that these enzymes provide resi stance to a wide variety of DNA damaging-agents; however, under certain cir cumstances. the eclectic nature of these enzymes can confer some biological disadvantages. Solving the X-ray crystal structures of two 3-methyladenine DNA glycosylases, and creating cells and animals altered for this activity , contributes to our understanding of their enzyme mechanism and how such e nzymes influence the biological response of organisms to several different types of DNA damage. BioEssays 21 :668-676, 1999. (C) 1999 John Wiley & Son s, Inc.