DNA glycosylase

DNA glycosylases are a family of enzymes involved in base excision repair, classified under EC number EC 3.2.2. Base excision repair is the mechanism by which damaged bases in DNA are removed and replaced. DNA glycosylases catalyze the first step of this process. They remove the damaged nitrogenous base while leaving the sugar-phosphate backbone intact, creating an apurinic/apyrimidinic site, commonly referred to as an AP site. This is accomplished by flipping the damaged base out of the double helix followed by cleavage of the N-glycosidic bond.[1]

Glycosylases were first discovered in bacteria, and have since been found in all kingdoms of life. In addition to their role in base excision repair, DNA glycosylase enzymes have been implicated in the repression of gene silencing in A. thaliana, N. tabacum and other plants by active demethylation. 5-methylcytosine residues are excised and replaced with unmethylated cytosines allowing access to the chromatin structure of the enzymes and proteins necessary for transcription and subsequent translation.[2][3]

  1. ^ Lindahl, T. (1986). "DNA Glycosylases in DNA Repair". Mechanisms of DNA Damage and Repair. Vol. 38. pp. 335–340. doi:10.1007/978-1-4615-9462-8_36. ISBN 978-1-4615-9464-2. PMID 3527146. {{cite book}}: |journal= ignored (help)
  2. ^ Aguis, F.; Kapoor, A; Zhu, J-K (2006). "Role of the Arabidopsis DNA glycosylase/lyase ROS1 in active DNA demethylation". Proc. Natl. Acad. Sci. U.S.A. 103 (31): 11796–11801. Bibcode:2006PNAS..10311796A. doi:10.1073/pnas.0603563103. PMC 1544249. PMID 16864782.
  3. ^ Choi, C-S.; Sano, H. (2007). "Identification of tobacco genes encoding proteins possessing removal activity of 5-methylcytosines from intact tobacco DNA". Plant Biotechnology. 24 (3): 339–344. doi:10.5511/plantbiotechnology.24.339.