title: Requirement of non-canonical activity of uracil DNA glycosylase for class switch recombination.
abstract: Activation-induced cytidine deaminase (AID) and uracil DNA glycosylase (UNG) are required for class switch recombination (CSR). AID is involved in the DNA cleavage step of CSR, but the precise role of UNG is not yet understood. Mutations and deletions are footprints of abortive DNA cleavage in the immunoglobulin switch region in splenic B cells stimulated to undergo CSR. However, a UNG deficiency did not reduce the number of such footprints, indicating UNG is dispensable for the DNA cleavage step. Mutagenesis experiments revealed that the role of UNG in CSR depends on its WXXF motif. This motif is also essential for the interaction of UNG with the HIV viral peptide Vpr, which recruits UNG to the HIV particle. Furthermore, exogenous Vpr had a dominant-negative effect on CSR. These results suggest that UNG is recruited to the CSR machinery through its WXXF motif by a Vpr-like host factor and plays a novel non-canonical role in a CSR step that follows DNA cleavage.
authors.affiliation: Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Nasim A
authors.initials: NA
authors.lastname: Begum
authors.forename: Nakako
authors.initials: N
authors.lastname: Izumi
authors.forename: Momoko
authors.initials: M
authors.lastname: Nishikori
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nagaoka
authors.forename: Reiko
authors.initials: R
authors.lastname: Shinkura
authors.forename: Tasuku
authors.initials: T
authors.lastname: Honjo
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism; D005799:Genes, Dominant; D006825:Hybridomas / Q000378:metabolism; D007075:Immunoglobulin M / Q000737:chemistry; D007136:Immunoglobulins / Q000737:chemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009154:Mutation; D011995:Recombination, Genetic; D017386:Sequence Homology, Amino Acid; D051981:Uracil-DNA Glycosidase / Q000737:chemistry*
chemical_list: D007075:Immunoglobulin M; D007136:Immunoglobulins; D051981:Uracil-DNA Glycosidase