Base excision repair
Each glycosylase detects and removes a specific kind of damaged base.
For example, a chemical reaction called deamination can convert a cytosine base into uracil, a base typically found only in RNA.
What does base excision repair fix?
Base excision repair (BER) is a cellular mechanism, studied in the fields of biochemistry and genetics, that repairs damaged DNA throughout the cell cycle. BER is initiated by DNA glycosylases, which recognize and remove specific damaged or inappropriate bases, forming AP sites.
What is the end result of base excision repair?
Base excision repair (BER) corrects small base lesions that do not significantly distort the DNA helix structure. Such damage typically results from deamination, oxidation, or methylation (Fig. 1). Enzymes that cleave the bond between deoxyribose and a modified or mismatched DNA base are now called DNA glycosylases.
What happens during nucleotide excision repair?
In nucleotide excision repair (NER), damaged bases are cut out within a string of nucleotides, and replaced with DNA as directed by the undamaged template strand. This repair system is used to remove pyrimidine dimers formed by UV radiation as well as nucleotides modified by bulky chemical adducts.
Which enzyme is involved in excision repair?
The process of nucleotide excision repair is controlled in Escherichia coli by the UvrABC endonuclease enzyme complex, which consists of four Uvr proteins: UvrA, UvrB, UvrC, and DNA helicase II (sometimes also known as UvrD in this complex).
Who discovered base excision repair?
2. The discovery of DNA glycosylases. The discovery of BER is credited to Tomas Lindahl (Fig. 1), who received the 2015 Nobel Prize in Chemistry for his contributions to the mechanism of this DNA repair mode. I first met Tomas in the summer of 1971 while attending a meeting on DNA repair at Johns Hopkins University.
What is the difference between base excision repair and nucleotide excision repair?
Excision repair: Damage to one or a few bases of DNA is often fixed by removal (excision) and replacement of the damaged region. In base excision repair, just the damaged base is removed. In nucleotide excision repair, as in the mismatch repair we saw above, a patch of nucleotides is removed.