Fig. 5.

Effect of nucleosome dissociation on integration catalyzed by HIV-1 and PFV integrases in vitro. Concerted integration assays were performed using either HIV-1 or PFV INs under similar conditions and using p601 vectors naked (lanes 1 and 4) or chromatinized with native histone octamers or H3/H4 tetramers with increasing histone/DNA ratios (lanes 2 and 5, 1.1 ratio; lanes 3 and 6, 1.2 ratio). Typical experiment is shown in (a) and quantification of the integration products is reported in (b). Comparison of the integration catalyzed by HIV-1 or PFV IN on naked and p601 vectors assembled with histone octamers or tetramers is shown in (c). Results are reported as the percentage relative to activity detected on naked DNA without FACT and pre-normalized data obtained in the control experiments using naked DNA are reported as the percentage of integrated substrate. Comparison of the effect of FACT on HIV-1 and PFV integration catalyzed on p601 chromatinized with histone octamers is shown in (d). All values are shown as the mean ± standard deviation (error bars) of at least three independent sets of experiments. The p-values were calculated by Student’s t-test and are shown as *p < 0.05 and **p < 0.005 to represent the probability of obtaining significant differences compared with untreated conditions