Fig. 4

Murine SAMHD1 isoforms potently restrict L1-GFP elements. a 293T cells were transfected with L1-GFP reporter plasmid or control vector (JM111) together with empty vector (pcDNA), mouse SAMHD1 isoform 1 (Iso1) or isoform 2 (Iso2), non-phosphorylated mutant T603A of Iso1, phosphomimetic Iso1 mutant T603D, the HD domain mutants HD/AA, or the allosteric site mutants D138A. b 293T cells were transfected with L1-GFP reporter plasmid or the control vector JM111, together with empty vector (pcDNA), human SAMHD1 (huSAMHD1), huSAMHD1 T592A (huT592A), and murine SAMHD1 Iso1 (muIso1) or Iso2 (muIso2). Five days later, GFP-positive cells were determined by flow cytometry. The percentage of L1-GFP positive cells is shown as average of triplicate transfections. Error bars indicate the standard deviation. Statistical analysis comparing control transfected cells and SAMHD1 expressing cells was done using one way ANOVA followed by Tukey’s multiple comparison test. *** p < 0.001; ns, not significant. For western blot analysis, 2 days posttransfection, SAMHD1 protein expression was analyzed by immunoblot using phosphoT592-specific or myc-specific antibodies. One out of three independent experiments is shown