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. 2008 Feb 13;82(9):4660–4664. doi: 10.1128/JVI.02469-07

FIG. 1.

FIG. 1.

APOBEC3G-mediated restriction of HIV (ΔVif) in human cells is independent of UNG. (A) Titration of transiently transfected Flag-tagged APOBEC3G (A3G), APOBEC3F (A3F), and a catalytically inactivated mutant of APOBEC3G (A3Gmut) in 293T cells, comparing their potencies in restricting HIV (ΔVif) infection. APOBEC3 expression plasmids (28), the HIV (ΔVif) vector p8.91 expressing the eGFP reporter (36), and viral infectivity assays in 293T cells are described elsewhere (28). A3Gmut has a cysteine-to-serine substitution at amino acid 288 that has been previously shown to compromise both deaminase and antiviral activities (13, 32, 34, 35, 40, 45, 53). (B) Infection assay showing that mutation load does not directly correlate with the level of inhibition of HIV (ΔVif) infection. Ctrl, control plasmid. Error bars indicate standard deviations. (C) Infection assay in 293T cells, showing that transient transfection of Ugi in A3G-expressing cells has no significant effect on HIV (ΔVif) restriction. (D) Oligonucleotide assay showing glycosylase activities of UNG and SMUG1 in 293T cell extracts. S indicates the uncleaved oligonucleotide substrate and P the cleaved product. Detailed procedures for the oligonucleotide assays were described previously (11). The amount of extract was such that the UNG activity in the control sample (lane 1) was sufficient to saturate the assay, shifting all the substrate to product.