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RPA guides UNG to uracil in ssDNA to facilitate antibody class switching and repair of mutagenic uracil at the replication fork.
- Source :
-
Nucleic acids research [Nucleic Acids Res] 2024 Jan 25; Vol. 52 (2), pp. 784-800. - Publication Year :
- 2024
-
Abstract
- Activation-induced cytidine deaminase (AID) interacts with replication protein A (RPA), the major ssDNA-binding protein, to promote deamination of cytosine to uracil in transcribed immunoglobulin (Ig) genes. Uracil-DNA glycosylase (UNG) acts in concert with AID during Ig diversification. In addition, UNG preserves genome integrity by base-excision repair (BER) in the overall genome. How UNG is regulated to support both mutagenic processing and error-free repair remains unknown. UNG is expressed as two isoforms, UNG1 and UNG2, which both contain an RPA-binding helix that facilitates uracil excision from RPA-coated ssDNA. However, the impact of this interaction in antibody diversification and genome maintenance has not been investigated. Here, we generated B-cell clones with targeted mutations in the UNG RPA-binding motif, and analysed class switch recombination (CSR), mutation frequency (5' Ig Sμ), and genomic uracil in clones representing seven Ung genotypes. We show that the UNG:RPA interaction plays a crucial role in both CSR and repair of AID-induced uracil at the Ig loci. By contrast, the interaction had no significant impact on total genomic uracil levels. Thus, RPA coordinates UNG during CSR and pre-replicative repair of mutagenic uracil in ssDNA but is not essential in post-replicative and canonical BER of uracil in dsDNA.<br /> (© The Author(s) 2023. Published by Oxford University Press on behalf of Nucleic Acids Research.)
- Subjects :
- Cytidine Deaminase genetics
Cytidine Deaminase metabolism
DNA Repair genetics
DNA, Single-Stranded genetics
Immunoglobulin Class Switching genetics
Immunoglobulin Isotypes genetics
Immunoglobulins genetics
Mutagens
Uracil metabolism
Humans
Animals
Mice
Replication Protein A genetics
Replication Protein A metabolism
Uracil-DNA Glycosidase genetics
Uracil-DNA Glycosidase metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1362-4962
- Volume :
- 52
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- Nucleic acids research
- Publication Type :
- Academic Journal
- Accession number :
- 38000394
- Full Text :
- https://doi.org/10.1093/nar/gkad1115