title: DNA polymerase ζ generates tandem mutations in immunoglobulin variable regions.
abstract: Low-fidelity DNA polymerases introduce nucleotide substitutions in immunoglobulin variable regions during somatic hypermutation. Although DNA polymerase (pol) η is the major low-fidelity polymerase, other DNA polymerases may also contribute. Existing data are contradictory as to whether pol ζ is involved. We reasoned that the presence of pol η may mask the contribution of pol ζ, and therefore we generated mice deficient for pol η and heterozygous for pol ζ. The frequency and spectra of hypermutation was unaltered between Polζ(+/-) Polη(-/-) and Polζ(+/+) Polη(-/-) clones. However, there was a decrease in tandem double-base substitutions in Polζ(+/-) Polη(-/-) cells compared with Polζ(+/+) Polη(-/-) cells, suggesting that pol ζ generates tandem mutations. Contiguous mutations are consistent with the biochemical property of pol ζ to extend a mismatch with a second mutation. The presence of this unique signature implies that pol ζ contributes to mutational synthesis in vivo. Additionally, data on tandem mutations from wild type, Polζ(+/-), Polζ(-/-), Ung(-/-), Msh2(-/-), Msh6(-/-), and Ung(-/-) Msh2(-/-) clones suggest that pol ζ may function in the MSH2-MSH6 pathway.
authors.affiliation: Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
authors.forename: Huseyin
authors.initials: H
authors.lastname: Saribasak
authors.forename: Robert W
authors.initials: RW
authors.lastname: Maul
authors.forename: Zheng
authors.initials: Z
authors.lastname: Cao
authors.forename: William W
authors.initials: WW
authors.lastname: Yang
authors.forename: Dominik
authors.initials: D
authors.lastname: Schenten
authors.forename: Sven
authors.initials: S
authors.lastname: Kracker
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Gearhart
mesh_terms: D000818:Animals; D002455:Cell Division / Q000235:genetics; D053843:DNA Mismatch Repair / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D004259:DNA-Directed DNA Polymerase / Q000235:genetics* / Q000378:metabolism; D006579:Heterozygote; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D051379:Mice; D008817:Mice, Mutant Strains; D051718:MutS Homolog 2 Protein / Q000235:genetics; D009154:Mutation; D027041:Somatic Hypermutation, Immunoglobulin; D051981:Uracil-DNA Glycosidase / Q000235:genetics; D000099270:Y-Family DNA Polymerases
chemical_list: D004268:DNA-Binding Proteins; D004259:DNA-Directed DNA Polymerase; D007135:Immunoglobulin Variable Region; D051718:MutS Homolog 2 Protein; D051981:Uracil-DNA Glycosidase; C102997:Msh6 protein, mouse; C425929:DNA polymerase zeta; C486862:REV3L protein, mouse; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases; C497173:Msh2 protein, mouse