Skip to main content
. 2010 Mar 29;78(6):2571–2583. doi: 10.1128/IAI.01107-09

FIG. 2.

FIG. 2.

Histidine 307 of LetS is required for the expression of PE-phase phenotypes. (A) The percentage of PE-phase bacteria that were viable and associated with macrophages after a 2-h incubation at an MOI of 1 is shown. (B) The fraction of viable macrophages was assessed by the reduction of the colorimetric dye alamarBlue after coculture for 1 h with PE-phase WT (circles), letS (squares), or letS(H307Q) (triangles) bacteria over a range of MOIs. Shown is a representative graph from three independent experiments preformed in triplicate. (C) The percentage of PE-phase bacteria that remained intact following a 2-h incubation with macrophages at an MOI of 1 was determined by fluorescence microscopy. (D) The percentage of sodium-resistant bacteria was determined after PE-phase cultures were plated on medium with or without 100 mM NaCl. (E) Soluble pigment in culture supernatants of WT, letS, and letS(H307Q) bacteria was quantified after a 5-day incubation period. For bar graphs in panels A, C, D, and E, the means ± standard deviations from duplicate samples in three independent experiments are displayed. Asterisks indicate statistically significant differences (P < 0.01) compared to WT PE-phase bacteria.