FIG 1.

A distinct pH threshold defines PsaE and PsaF levels and impacts PsaF stability. (A) The wild type (WT; YP6) was grown at 37°C in brain heart infusion (BHI) buffered to pH 6.3, 6.5, 6.7, 7.0, and 7.3, and PsaE and PsaF were analyzed via Western blot as described in Materials and Methods. As a control, whole-cell lysates of the ΔpsaEF mutant (YPA18) grown at 37°C in BHI pH 6.3 were also analyzed. (B) WT was grown in BHI pH 6.3 for 8 h, cells were pelleted, washed and suspended in phosphate-buffered saline (PBS) adjusted to pH 6.3 or pH 7.3 as indicated in Materials and Methods, and PsaE and PsaF were analyzed over time. LC, loading control from Ponceau S-stained membrane.