Figure 3.

Mitochondrial respiration restricts L. monocytogenes entry into host cells

(A–D) Quantification of L. monocytogenes EGD (MOI, 20; 1 h) adhered to the surface (A and C) of and internalized by (B and D) HCT116 Glc and Gal cells (A and B) or HCT116 WT, SURF1^−/−, and SURF1^−/− + SURF1 cells (C and D) by immunofluorescence. Results are representative of four (A and B) and three (C and D) independent experiments and are displayed as box and whiskers plot with absolute numbers of bacteria per cell (with n > 570 cells per condition) and mean indicated by +. Given the non-Gaussian distribution, statistical significance was determined using a two-tailed Mann Whitney test (A and B) or a Kruskal-Wallis test followed by Dunn’s multiple comparisons test (C and D) (^∗p < 0.05; ^∗∗∗p < 0.001).

(E and F) Quantification of intracellular L. monocytogenes EGD in HCT116 Glc and Gal cells (E) or HCT116 WT, SURF1^−/−, and SURF1^−/− + SURF1 cells (F) after infection with WT or InlA-deficient (ΔinlA), InlB-deficient (ΔinlB), or LLO-deficient (Δhly) bacterial strains for 1 h. Three independent experiments were performed, and data from one representative experiment with three biological replicates are shown as relative CFU/mL with values normalized to the control condition (Glc or WT cells). Statistical significance was determined by two-tailed t tests (E) or one-way ANOVAs with Dunnett’s post hoc test (F) (^∗p < 0.05; ^∗∗p < 0.01; ^∗∗∗p < 0.001).