Phosphorylation directly regulates the intrinsic DNA cytidine deaminase activity of activation-induced deaminase and APOBEC3G protein |
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Authors: | Demorest Zachary L Li Ming Harris Reuben S |
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Affiliation: | Department of Biochemistry, Molecular Biology, and Biophysics, Institute for Molecular Virology, and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA. |
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Abstract: | The beneficial effects of DNA cytidine deamination by activation-induced deaminase (AID; antibody gene diversification) and APOBEC3G (retrovirus restriction) are tempered by probable contributions to carcinogenesis. Multiple regulatory mechanisms serve to minimize this detrimental outcome. Here, we show that phosphorylation of a conserved threonine attenuates the intrinsic activity of activation-induced deaminase (Thr-27) and APOBEC3G (Thr-218). Phospho-null alanine mutants maintain intrinsic DNA deaminase activity, whereas phospho-mimetic glutamate mutants are inactive. The phospho-mimetic variants fail to mediate isotype switching in activated mouse splenic B lymphocytes or suppress HIV-1 replication in human T cells. Our data combine to suggest a model in which this critical threonine acts as a phospho-switch that fine-tunes the adaptive and innate immune responses and helps protect mammalian genomic DNA from procarcinogenic lesions. |
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Keywords: | Antibodies DNA Enzymes DNA Repair HIV Innate Immunity AID APOBEC3G DNA Cytosine Deaminase DNA Editing |
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