The PhoPR two component system is required for LMP, lipase activation, mitochondrial injury and death of Mtb-infected macrophages.
(A) Macrophages were challenged with RvΔphoPR or parental H37Rv and LMP was measured by cytosolic translocation of cathepsin B 2 h later. Results are expressed as mean fold increase of cytosolic cathepsin B activity ± SEM. * P<0.05. (B) Mitochondrial injury (ΔΨm dissipation) was measured in macrophages challenged with H37Rv as compared to RvΔRD1ΔespA (left panel) or RvΔphoPR (right panel) using Mitotracker Deep Red. Histograms are representative of three independent experiments. (C) Cell death assessed by PI incorporation was measured in uninfected macrophages and macrophages challenged with H37Rv, RvΔRD1ΔespA, or RvΔphoPR (18 h). A representative experiment of three performed is depicted. * P<0.05 comparing cells infected with H37Rv or RvΔRD1ΔespA to uninfected cells or cells infected with RvΔphoPR. Error bars, ± SD.
