Fig. 6.

Iron increases and zinc decreases HIV-1 Tat oligomerization. A HIV-1 Tat protein (7.0 μg/ml) was incubated at 37 °C for 3 h with 20 μM concentrations (pH 5.5) of FeCl₂, FeCl₃, and ZnCl₂ followed by gel electrophoresis separation using 4–16% Bis–Tris native gels. FeCl₃ and less so FeCl₂ increased the molecular mass of HIV-1 Tat; ZnCl₂ had no observable effect. B, C Tat protein (7.0 μg/ml) was incubated at 37 °C for 3 h with 20 μM concentrations (pH 5.5) of FeCl₂, FeCl₃, and ZnCl₂ followed by gel electrophoresis separation using 15% SDS-PAGE and immunoblotting. FeCl₂ and FeCl₃ increased significantly (p < 0.001) and ZnCl₂ decreased significantly (p < 0.05) the ratio of HIV-1 Tat oligomer to dimer. Thus, iron increased, and zinc decreased levels of the less-active oligomeric form of HIV-1 Tat