Title |
Negative Supercoiling Creates Single-Stranded Patches of DNA That Are Substrates for AID–Mediated Mutagenesis
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Published in |
PLoS Genetics, February 2012
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DOI | 10.1371/journal.pgen.1002518 |
Pubmed ID | |
Authors |
Jahan-Yar Parsa, Shaliny Ramachandran, Ahmad Zaheen, Rajeev M. Nepal, Anat Kapelnikov, Antoaneta Belcheva, Maribel Berru, Diana Ronai, Alberto Martin |
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 negative supercoiling enhances both ssDNA tract formation and AID mutagenesis. In addition, RNaseH1 expression does not impact the formation of these ssDNA tracts indicating that these structures are distinct from R-loops. These data emphasize the notion that these transcription-generated ssDNA tracts are one of many in vivo substrates for AID. |
Mendeley readers
Geographical breakdown
Country | Count | As % |
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United States | 1 | 2% |
Unknown | 60 | 98% |
Demographic breakdown
Readers by professional status | Count | As % |
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Student > Ph. D. Student | 19 | 31% |
Researcher | 14 | 23% |
Student > Master | 4 | 7% |
Student > Bachelor | 4 | 7% |
Student > Doctoral Student | 3 | 5% |
Other | 10 | 16% |
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Unspecified | 1 | 2% |
Other | 1 | 2% |
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