title: Inhibition of APOBEC3G activity impedes double-stranded DNA repair.
abstract: The cellular cytidine deaminase APOBEC3G (A3G) was first described as an anti-HIV-1 restriction factor, acting by directly deaminating reverse transcripts of the viral genome. HIV-1 Vif neutralizes the activity of A3G, primarily by mediating degradation of A3G to establish effective infection in host target cells. Lymphoma cells, which express high amounts of A3G, can restrict Vif-deficient HIV-1. Interestingly, these cells are more stable in the face of treatments that result in double-stranded DNA damage, such as ionizing radiation and chemotherapies. Previously, we showed that the Vif-derived peptide (Vif25-39) efficiently inhibits A3G deamination, and increases the sensitivity of lymphoma cells to ionizing radiation. In the current study, we show that additional peptides derived from Vif, A3G, and APOBEC3F, which contain the LYYF motif, inhibit deamination activity. Each residue in the Vif25-39 sequence moderately contributes to the inhibitory effect, whereas replacing a single residue in the LYYF motif completely abrogates inhibition of deamination. Treatment of A3G-expressing lymphoma cells exposed to ionizing radiation with the new inhibitory peptides reduces double-strand break repair after irradiation. Incubation of cultured irradiated lymphoma cells with peptides that inhibit double-strand break repair halts their propagation. These results suggest that A3G may be a potential therapeutic target that is amenable to peptide and peptidomimetic inhibition.
authors.affiliation: Department of Pathology and Immunology, the Lautenberg Center for General and Tumor Immunology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
authors.forename: Ponnandy
authors.initials: P
authors.lastname: Prabhu
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA.
authors.forename: Shivender M D
authors.initials: SM
authors.lastname: Shandilya
authors.affiliation: Department of Pathology and Immunology, the Lautenberg Center for General and Tumor Immunology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
authors.forename: Elena
authors.initials: E
authors.lastname: Britan-Rosich
authors.affiliation: Department of Pathology and Immunology, the Lautenberg Center for General and Tumor Immunology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
authors.forename: Adi
authors.initials: A
authors.lastname: Nagler
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA.
authors.forename: Celia A
authors.initials: CA
authors.lastname: Schiffer
authors.affiliation: Department of Pathology and Immunology, the Lautenberg Center for General and Tumor Immunology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
authors.forename: Moshe
authors.initials: M
authors.lastname: Kotler
mesh_terms: D000071480:APOBEC-3G Deaminase; D055162:Biocatalysis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003564:Cytidine Deaminase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004247:DNA / Q000187:drug effects* / Q000378:metabolism; D004260:DNA Repair / Q000187:drug effects*; D006801:Humans; D007700:Kinetics; D010455:Peptides / Q000494:pharmacology*
chemical_list: D010455:Peptides; D004247:DNA; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase
keywords: APOBEC3G; DNA binding; DNA repair; lymphoma cells; peptides