2A-12 The role of 3-methyladenine DNA glycosylases Mag1p and Mag2p from Schizosaccharomyces pombe in base excision repair of alkylation damage

• Published in: Genes & Genetic Systems Vol. 81; no. 6; p. 412
• Main Authors: IKEDA Shogo, TANIHIGASHI Haruna, KANAMITSU Kyoichiro, TANITA Yoshie
• Format: Journal Article
• Language: Japanese
• Published: The Genetics Society of Japan 2006
• ISSN: 1341-7568

Schizosaceharomyces pombe has two paralogues of 3-methylade-nine DNA glycosylases, mag1 and mag2, which share homology with Escherichia coli alkA and Saccharomyces cerevisiae mag1. To clarify the redundancy of these enzymes in repair of alkylation damage, we performed several genetic analyses. A double mutant of mag1 and mag2 as well as each single mutant did not show any MMS sensitivity. On the other hand, Rad16p-deficient cells exhibited resistance to MMS treatment. Deletion of mag1 from a rad16 mutant increased the sensitivity to MMS. Expression of Mag1p in E. coli alkAΔ and S. cerevisiae mag1Δ cells could restore the resistance to MMS of these mutants, but Mag2p did not complement the defect of the cells. In S. pombe cells Nth1p is the major enzyme to incise the AP sites, so the Nth1p-deficent cells exhibit hypersensitivity to MMS. Deletion of mag1 from an nth1 mutant resulted in tolerance to MMS damage. A mag2Δ/nth1Δ double mutant weakly restored the MMS resistance. These results suggest that the nucleotide excision repair is also involved in processing MMS damage and that Mag1p plays the major role for removal of alkylated bases.