Document Detail


Stochastic properties of processive cytidine DNA deaminases AID and APOBEC3G.
MedLine Citation:
PMID:  19022738     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Activation-induced (cytidine) deaminase (AID) efficiently introduces multiple and diversified deaminations in immunoglobulin (Ig) variable and switch regions. Here, we review studies of AID, and the APOBEC family member, APOBEC3G, demonstrating that both enzymes introduce multiple deaminations by processive action on single-stranded DNA and that deaminations occur stochastically at hot- and cold-spot targets. In a more detailed analysis of AID, we examine phosphorylation-null mutants, particularly, S38A and S43P. S43P mutant AID has been identified in a patient with hyper-IgM immunodeficiency syndrome. The phosphorylation-null mutants have essentially the same specific activity, processivity and ability to undergo transcription-dependent deamination compared with wild-type (WT) AID. Although the phosphorylation-null mutants still deaminate 5'-WRC hot spots, the mutant deamination spectra differ from WT AID. The mutants strongly prefer two motifs, 5'AGC and 5'GGC, which are disfavoured by WT AID. Differences in deamination specificities can be attributed primarily to the replacement of Ser rather than to the absence of phosphorylation. The 5'GGC motif occurs with exceptionally high frequency on the non-transcribed strand of human switch regions, IgG4 and IgE. The potential for S43P to catalyse large numbers of aberrant deaminations in switch region sequences suggests a possible relationship between non-canonical AID deamination specificity and a loss of antibody diversification.
Authors:
Linda Chelico; Phuong Pham; Myron F Goodman
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Review    
Journal Detail:
Title:  Philosophical transactions of the Royal Society of London. Series B, Biological sciences     Volume:  364     ISSN:  1471-2970     ISO Abbreviation:  Philos. Trans. R. Soc. Lond., B, Biol. Sci.     Publication Date:  2009 Mar 
Date Detail:
Created Date:  2009-01-29     Completed Date:  2009-03-27     Revised Date:  2010-09-23    
Medline Journal Info:
Nlm Unique ID:  7503623     Medline TA:  Philos Trans R Soc Lond B Biol Sci     Country:  England    
Other Details:
Languages:  eng     Pagination:  583-93     Citation Subset:  IM    
Affiliation:
Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-2910, USA.
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MeSH Terms
Descriptor/Qualifier:
Antibodies / genetics
Cytidine Deaminase / metabolism*
Deamination
Humans
Hyper-IgM Immunodeficiency Syndrome / genetics*
Immunoglobulin Class Switching / immunology*
Models, Genetic
Mutation / genetics
Phosphorylation
Stochastic Processes*
Grant Support
ID/Acronym/Agency:
ESO13192//PHS HHS; R37GM21422/GM/NIGMS NIH HHS
Chemical
Reg. No./Substance:
0/Antibodies; EC 3.5.4.-/AICDA (activation-induced cytidine deaminase); EC 3.5.4.5/APOBEC3G protein, human; EC 3.5.4.5/Cytidine Deaminase
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