Fig. 4: McpC functions independently of T3SS1 to increase bacterial/host cell association. | Nature Communications

Fig. 4: McpC functions independently of T3SS1 to increase bacterial/host cell association.

From: Regulatory protein HilD stimulates Salmonella Typhimurium invasiveness by promoting smooth swimming via the methyl-accepting chemotaxis protein McpC

Fig. 4

a T3SS1 gene expression is not altered in ΔmcpC. SPI1-induced bacteria harboring PprgH gfp [LVA] were analyzed by flow cytometry (n = 3 independent experiments). The mean ± SD percentage of GFP-positive bacteria (left panel) and the mean fluorescence intensity (right panel) are shown. Significance was determined using a two-tailed, paired Student’s t test (WT vs. ΔmcpC, % GFP positive: p = 0.2, WT vs. ΔmcpC, MFI: p = 0.1). b HeLa cells were infected with WT and ΔmcpC using centrifugation to synchronize bacterial/host association. Shown are the mean ± SD ruffle sizes from WT infected cells (n = 132 cells, examined over three independent experiments) and from ΔmcpC infected cells (n = 157 cells, examined over three independent experiments). Significance was determined using a two-tailed, paired Student’s t test (WT vs. ΔmcpC; p = 0.4). c HeLa cells were infected with the indicated strains with or without centrifugation. Shown are the mean ± SD fold increases in internalization with centrifugation at 1.5 h pi from n = 3 independent experiments. Significance was determined by two-way Anova of log-transformed values followed by Tukey’s multiple comparisons (WT vs. ΔmcpC; p = 0.002, WT vs. ΔfliC; p = 0.03, WT vs. ΔSPI1: p = 0.7). d HeLa cells were infected with ΔinvA or ΔinvA/ΔmcpC, with or without expression of invasin (as indicated) for 6 min. Shown are the mean ± SD percentage of cells with associated bacteria (ΔinvA; n = 1212 cells examined over three independent experiments, ΔinvA + Invasin; n = 1518 cells examined over three independent experiments, ΔinvA/ΔmcpC; n = 1173 cells examined over three independent experiments, ΔinvA/ΔmcpC + Invasin; n = 1489 cells examined over three independent experiments). Significance was determined by one-way Anova followed by Tukey’s multiple comparisons (ΔinvA + Invasin vs. ΔinvA/ΔmcpC + Invasin; p = 0.0001. Green bars indicate that GFP-positive bacteria were analyzed in the assay. ns not significant, *p < 0.05. Source data are provided as a Source Data file.

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