Human activation-induced deaminase lacks strong replicative strand bias or preference for cytosines in hairpin loops.

Activation-induced deaminase (AID) is a DNA-cytosine deaminase that mediates maturation of antibodies through somatic hypermutation and class-switch recombination. While it causes mutations in immunoglobulin heavy and light chain genes and strand breaks in the switch regions of the immunoglobulin heavy chain gene, it largely avoids causing such damage in the rest of the genome. To help understand targeting by human AID, we expressed it in repair-deficient Escherichia coli and mapped the created uracils in the genomic DNA using uracil pull-down and sequencing, UPD-seq.

FAM72A antagonizes UNG2 to promote mutagenic repair during antibody maturation.

Activation-induced cytidine deaminase (AID) catalyses the deamination of deoxycytidines to deoxyuracils within immunoglobulin genes to induce somatic hypermutation and class-switch recombination. AID-generated deoxyuracils are recognized and processed by subverted base-excision and mismatch repair pathways that ensure a mutagenic outcome in B cells. However, why these DNA repair pathways do not accurately repair AID-induced lesions remains unknown.

Genome-wide mapping of regions preferentially targeted by the human DNA-cytosine deaminase APOBEC3A using uracil-DNA pulldown and sequencing.

Activation-induced deaminase (AID) and apolipoprotein B mRNA-editing enzyme catalytic subunit (APOBEC) enzymes convert cytosines to uracils, creating signature mutations that have been used to predict sites targeted by these enzymes. Mutation-based targeting maps are distorted by the error-prone or error-free repair of these uracils and by selection pressures. To directly map uracils created by AID/APOBEC enzymes, here we used uracil-DNA glycosylase and an alkoxyamine to covalently tag and sequence uracil-containing DNA fragments (UPD-Seq).

A Tumor-Promoting Phorbol Ester Causes a Large Increase in APOBEC3A Expression and a Moderate Increase in APOBEC3B Expression in a Normal Human Keratinocyte Cell Line without Increasing Genomic Uracils.

Phorbol 12-myristate 13-acetate (PMA) promotes skin cancer in rodents. The mutations found in murine tumors are similar to those found in human skin cancers, and PMA promotes proliferation of human skin cells. PMA treatment of human keratinocytes increases the synthesis of APOBEC3A, an enzyme that converts cytosines in single-stranded DNA to uracil, and mutations in a variety of human cancers are attributed to APOBEC3A or APOBEC3B expression.

A novel class of chemicals that react with abasic sites in DNA and specifically kill B cell cancers.

Most B cell cancers overexpress the enzyme activation-induced deaminase at high levels and this enzyme converts cytosines in DNA to uracil. The constitutive expression of this enzyme in these cells greatly increases the uracil content of their genomes. We show here that these genomes also contain high levels of abasic sites presumably created during the repair of uracils through base-excision repair.