Fig. 5: Hypotonic release of the periplasm without lysing Synechococcus sp. WH8102 cells.

Western blotting of periplasmic and cell lysate proteins (a, b). Cells were subjected to 1 min hypotonic shock in deionized water (DW) and pelleted to separate treated cells from supernatant. Proteins present in the DW supernatant were compared with proteins in the lysate (L) of treated cells. a Western blot immunolabeling with antibodies against the periplasmic P_i-binding subunit PstS and the large Rubisco subunit RbcL (5, 10 or 20 μl per lane) reveals the presence of PstS but no signal for RbcL in the DW supernatant. b Coomassie-stained SDS-PAGE (10 μl per lane) with the size range of proteins in the L and DW samples is shown for reference. Mw, molecular-weight size marker (kDa). The experiment was repeated independently four times with similar results. Comparison of control (left column) and DW-treated cells (right column) using flow cytometric pseudo-colour plots (c) of cellular orange or green autofluorescence vs. red autofluorescence or side scatter. Visualized in BD CellQuest™ Pro, cellular light scatter and autofluorescence of photosynthetic pigments cluster cells in a single cytometric population separate from a dispersed cluster of other suspended particles and tight clusters of reference beads. Compared with the control cells incubated in ASW medium, the cells incubated in DW for 0.5 h have higher autofluorescence but still form a single population, which shows minor deterioration, i.e., cell lysis. Cells were analysed without fixation or staining. The yellow-green (505/515 nm) 0.5 μm beads (circled in dark blue) and multifluorescence 1.0 μm beads (circled in red) were used as an internal reference. Source data are provided as a Source Data file.