title: APOBEC3G inhibits HIV-1 RNA elongation by inactivating the viral trans-activation response element.
abstract: Deamination of cytidine residues in viral DNA is a major mechanism by which APOBEC3G (A3G) inhibits vif-deficient human immunodeficiency virus type 1 (HIV-1) replication. dC-to-dU transition following RNase-H activity leads to viral cDNA degradation, production of non-functional proteins, formation of undesired stop codons and decreased viral protein synthesis. Here, we demonstrate that A3G provides an additional layer of defense against HIV-1 infection dependent on inhibition of proviral transcription. HIV-1 transcription elongation is regulated by the trans-activation response (TAR) element, a short stem-loop RNA structure required for elongation factors binding. Vif-deficient HIV-1-infected cells accumulate short viral transcripts and produce lower amounts of full-length HIV-1 transcripts due to A3G deamination of the TAR apical loop cytidine, highlighting the requirement for TAR loop integrity in HIV-1 transcription. We further show that free single-stranded DNA (ssDNA) termini are not essential for A3G activity and a gap of CCC motif blocked with juxtaposed DNA or RNA on either or 3'+5' ends is sufficient for A3G deamination. These results identify A3G as an efficient mutator and that deamination of (-)SSDNA results in an early block of HIV-1 transcription.
authors.affiliation: Department of Pathology and Lautenberg Center for General and Tumor Immunology, Jerusalem 91120, Israel.
authors.forename: Roni
authors.initials: R
authors.lastname: Nowarski
authors.affiliation: Department of Pathology and Lautenberg Center for General and Tumor Immunology, Jerusalem 91120, Israel.
authors.forename: Ponnandy
authors.initials: P
authors.lastname: Prabhu
authors.affiliation: Department of Pathology and Lautenberg Center for General and Tumor Immunology, Jerusalem 91120, Israel.
authors.forename: Edan
authors.initials: E
authors.lastname: Kenig
authors.affiliation: Genomic Data Analysis Unit, The Hebrew University Hadassah Medical School, Jerusalem 91120, Israel.
authors.forename: Yoav
authors.initials: Y
authors.lastname: Smith
authors.affiliation: Department of Pathology and Lautenberg Center for General and Tumor Immunology, Jerusalem 91120, Israel.
authors.forename: Elena
authors.initials: E
authors.lastname: Britan-Rosich
authors.affiliation: Department of Pathology and Lautenberg Center for General and Tumor Immunology, Jerusalem 91120, Israel. Electronic address: moshek@ekmd.huji.ac.il.
authors.forename: Moshe
authors.initials: M
authors.lastname: Kotler
mesh_terms: D000071480:APOBEC-3G Deaminase; D020029:Base Pairing; D001483:Base Sequence; D015152:Blotting, Northern; D003564:Cytidine Deaminase / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000235:genetics*; D004279:DNA, Viral / Q000235:genetics*; D024202:Electrophoretic Mobility Shift Assay; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012367:RNA, Viral / Q000235:genetics; D020218:Response Elements / Q000235:genetics*; D014158:Transcription, Genetic; D014775:Virus Activation / Q000502:physiology*; D014779:Virus Replication; D054320:vif Gene Products, Human Immunodeficiency Virus / Q000235:genetics
chemical_list: D004277:DNA, Single-Stranded; D004279:DNA, Viral; D012367:RNA, Viral; D054320:vif Gene Products, Human Immunodeficiency Virus; C514847:vif protein, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase
keywords: APOBEC3G; HIV-1; Tat; deamination; ssDNA