{"doi":"10.17615/95e3-2k83","title":"Activation-induced deaminase, AID, is catalytically active as a monomer on single-stranded DNA","abstract":"Hypermutation and class switch recombination of immunoglobulin genes are antigen-activated mechanisms triggered by AID, a cytidine deaminase. AID deaminates cytidine residues in the DNA of the variable and the switch regions of the immunoglobulin locus. The resulting uracil induces error-prone DNA synthesis in the case of hypermutation or DNA breaks that activate non-homologous recombination in the case of class-switch recombination. In vitro studies have demonstrated that AID deaminates single-stranded but not double-stranded substrates unless AID is in a complex with RPA and the substrate is actively undergoing transcription. However, it is not clear whether AID deaminates its substrates primarily as a monomer or as a higher order oligomer. To examine the oligomerization state of AID alone and in the presence of single stranded DNA substrates of various structures, including loops embedded in double-stranded DNA, we used atomic force microscopy (AFM) to visualize AID protein alone or in complex with DNA. Surprisingly, AFM results indicate that most AID molecules exist as a monomer and that it binds single-stranded DNA substrates as a monomer at concentrations where efficient deamination of single-stranded DNA substrates occur. The rate of deamination, under conditions of excess and limiting protein, also imply that AID can deaminate single-stranded substrates as a monomer. These results imply that non-phosphorylated AID is catalytically active as a monomer on single stranded DNA in vitro, including single-stranded DNA found in loops similar to those transiently formed in the immunoglobulin switch regions during transcription.","journal":"UNC Libraries","year":2021,"id":231111,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9578,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":546747,"name":"Marilyn Diaz","orcid":"0000-0002-3046-2746","position":1,"is_corresponding":false},{"id":544154,"name":"Ingrid Teßmer","orcid":"0000-0002-8353-6315","position":2,"is_corresponding":false},{"id":547117,"name":"Elizabeth J. Sacho","orcid":"0000-0002-4499-5869","position":3,"is_corresponding":false},{"id":259276,"name":"Deborah L. Croteau","orcid":"0000-0002-6094-4084","position":4,"is_corresponding":false},{"id":4637,"name":"Dorothy A. Erie","orcid":"0000-0003-0363-4693","position":5,"is_corresponding":false},{"id":611369,"name":"Sukhdev S. Brar","orcid":null,"position":0,"is_corresponding":true}],"reference_count":0,"raw_metadata":null,"created_at":"2026-07-18T23:55:12.400773Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}