Lesions Processed By BER
Single bases in DNA can be chemically damaged by a variety of mechanisms, the most common ones being deamination, oxidation, and alkylation. These modifications can affect the ability of the base to hydrogen-bond, resulting in incorrect base-pairing, and, as a consequence, mutations in the DNA. For example, incorporation of adenine across from 8-oxoguanine (right) during DNA replication causes a G:C base pair to be mutated to T:A. Other examples of base lesions repaired by BER include:
- Oxidized bases: 8-oxoguanine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyG, FapyA)
- Alkylated bases: 3-methyladenine, 7-methylguanine
- Deaminated bases: hypoxanthine formed from deamination of adenine. Xanthine formed from deamination of guanine. (Thymidine products following deamination of 5-methylcytosine are not repaired)
- Uracil inappropriately incorporated in DNA or formed by deamination of cytosine
In addition to base lesions, the downstream steps of BER are also utilized to repair single-strand breaks.
Read more about this topic: Base Excision Repair
Famous quotes containing the word lesions:
“Not that success, for him, is sure, infallible.
But never has he been afraid to reach.
His lesions are legion.
But reaching is his rule.”
—Gwendolyn Brooks (b. 1917)