Biochemistry, Biophysics, and Structural Biology Commons^™

Methyl- And Normal-Cytosine Deamination By The Foreign Dna Restriction Enzyme Apobec3a, Michael Carpenter, Ming Li, Anurag Rathore, Lela Lackey, Emily Law, Allison Land, Brandon Leonard, Shivender Shandilya, Markus-Frederik Bohn, Celia Schiffer, William Brown, Reuben Harris

Celia A. Schiffer

Multiple studies have indicated that the TET oxidases and, more controversially, the AID/APOBEC deaminases have the capacity to convert genomic DNA 5-methylcytosine (MeC) into altered nucleobases that provoke excision repair and culminate in the replacement of the original MeC with a normal cytosine (C). We show that human APOBEC3A (A3A) efficiently deaminates both MeC to thymine (T) and normal C to uracil (U) in single-stranded DNA substrates. In comparison, the related enzyme APOBEC3G (A3G) has undetectable MeC-to-T activity and 10-fold less C-to-U activity. Upon 100-fold induction of endogenous A3A by interferon, the MeC status of bulk chromosomal DNA is unaltered …