Negative supercoiling creates single-stranded patches of DNA that are substrates for AID-mediated mutagenesis.

ABSTRACT: Antibody diversification necessitates targeted mutation of regions within the immunoglobulin locus by activation-induced cytidine deaminase (AID). While AID is known to act on single-stranded DNA (ssDNA), the source, structure, and distribution of these substrates in vivo remain unclear. Using the technique of in situ bisulfite treatment, we characterized these substrates-which we found to be unique to actively transcribed genes-as short ssDNA regions, that are equally distributed on both DNA strands. We found that the frequencies of these ssDNA patches act as accurate predictors of AID activity at reporter genes in hypermutating and class switching B cells as well as in Escherichia coli. Importantly, these ssDNA patches rely on transcription, and we report that transcription-induced negat

SUBMITTER: Parsa JY 

PROVIDER: S-EPMC3276561 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature