C-terminal deletion of AID uncouples class switch recombination from somatic hypermutation and gene conversion.
Class-switch recombination (CSR), somatic hypermutation (SHM), and antibody gene conversion are distinct DNA modification reactions, but all are initiated by activation-induced cytidine deaminase (AID), an enzyme that deaminates cytidine residues in single-stranded DNA. Here we describe a mutant form of AID that catalyzes SHM and gene conversion but not CSR. When expressed in E. coli, AID(delta189-198) is more active in catalyzing cytidine deamination than wild-type AID. AID(delta189-198) also promotes high levels of gene conversion and SHM when expressed in eukaryotic cells, but fails to induce CSR. These results underscore an essential role for the C-terminal domain of AID in CSR that is independent of its cytidine deaminase activity and that is not required for either gene conversion or SHM.
Barreto
Vasco
V
Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10021, USA.
Reina-San-Martin
Bernardo
B
Ramiro
Almudena R
AR
McBride
Kevin M
KM
Nussenzweig
Michel C
MC
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002645:Chickens; D003564:Cytidine Deaminase / Q000737:chemistry* / Q000235:genetics*; D004926:Escherichia coli / Q000378:metabolism; D005434:Flow Cytometry; D017353:Gene Deletion; D049452:Green Fluorescent Proteins; D006801:Humans; D017578:Immunoglobulin Class Switching; D015847:Interleukin-4 / Q000378:metabolism; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D012190:Retroviridae / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013997:Time Factors; D000098830:AICDA (Activation-Induced Cytidine Deaminase)
D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D015847:Interleukin-4; D000098830:AICDA (Activation-Induced Cytidine Deaminase); D003564:Cytidine Deaminase