title: DNA polymerase ι functions in the generation of tandem mutations during somatic hypermutation of antibody genes.
abstract: DNA polymerase ι (Pol ι) is an attractive candidate for somatic hypermutation in antibody genes because of its low fidelity. To identify a role for Pol ι, we analyzed mutations in two strains of mice with deficiencies in the enzyme: 129 mice with negligible expression of truncated Pol ι, and knock-in mice that express full-length Pol ι that is catalytically inactive. Both strains had normal frequencies and spectra of mutations in the variable region, indicating that loss of Pol ι did not change overall mutagenesis. We next examined if Pol ι affected tandem mutations generated by another error-prone polymerase, Pol ζ. The frequency of contiguous mutations was analyzed using a novel computational model to determine if they occur during a single DNA transaction or during two independent events. Analyses of 2,000 mutations from both strains indicated that Pol ι-compromised mice lost the tandem signature, whereas C57BL/6 mice accumulated significant amounts of double mutations. The results support a model where Pol ι occasionally accesses the replication fork to generate a first mutation, and Pol ζ extends the mismatch with a second mutation.
authors.affiliation: Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224.
authors.forename: Robert W
authors.identifier: 0000-0002-6958-8514
authors.initials: RW
authors.lastname: Maul
authors.affiliation: Department of Applied Mathematics and Statistics, State University of New York, Stony Brook, NY 11794.
authors.forename: Thomas
authors.identifier: 0000-0003-0025-9285
authors.initials: T
authors.lastname: MacCarthy
authors.affiliation: Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD 20850.
authors.forename: Ekaterina G
authors.identifier: 0000-0003-3932-8399
authors.initials: EG
authors.lastname: Frank
authors.affiliation: Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD 20850.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Donigan
authors.affiliation: Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD 20850.
authors.forename: Mary P
authors.identifier: 0000-0003-2642-5771
authors.initials: MP
authors.lastname: McLenigan
authors.affiliation: Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224.
authors.forename: William
authors.identifier: 0000-0001-8382-0773
authors.initials: W
authors.lastname: Yang
authors.affiliation: Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224.
authors.forename: Huseyin
authors.identifier: 0000-0003-0055-062X
authors.initials: H
authors.lastname: Saribasak
authors.affiliation: Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD 20850.
authors.forename: Donald E
authors.initials: DE
authors.lastname: Huston
authors.affiliation: Department of Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center Science Park, Smithville, TX 78957.
authors.forename: Sabine S
authors.initials: SS
authors.lastname: Lange
authors.affiliation: Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD 20850.
authors.forename: Roger
authors.identifier: 0000-0001-5581-4616
authors.initials: R
authors.lastname: Woodgate
authors.affiliation: Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224 gearhartp@mail.nih.gov.
authors.forename: Patricia J
authors.identifier: 0000-0003-1975-4737
authors.initials: PJ
authors.lastname: Gearhart
mesh_terms: D000818:Animals; D004259:DNA-Directed DNA Polymerase / Q000502:physiology*; D005803:Genes, Immunoglobulin; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D027041:Somatic Hypermutation, Immunoglobulin; D000094769:DNA Polymerase iota
chemical_list: C425929:DNA polymerase zeta; D004259:DNA-Directed DNA Polymerase; D000094769:DNA Polymerase iota