FIG 9.

Septal accumulation of TolA is very sensitive to interference with PBP3 activity. Live cells were imaged with DIC, and GFP and RFP fluorescence optics as indicated. Cultures of strain CH244 (Δ[tolQ-cpoB) zipA-rfp^SW) carrying pCH633 (P_BAD::tolQ-gfp) (A, C, and E) or pCH634 (P_BAD::gfp-tolA) (B, D, and F) were grown in parallel for ∼3.5 mass doublings to OD₆₀₀ = 0.6 to 0.7 in M9-glucose medium with 0.005% (A, C, and E) or 0.03% (B, D, and F) arabinose. Aztreonam was omitted (A and B) or added to 20 ng/mL (C and D) or 50 ng/mL (E and F) ∼2 mass doublings before imaging. Bar equals 2.0 μm. Sites of cell constriction with strong accumulations of ZipA-RFP^SW are evident in panels E and F. While clear accumulations of TolQ-GFP at these sites can still be seen (E, stars), GFP-TolA appears to be partially excluded from such sites (F, arrowheads).