TABLE 4.

Osmotic upshock responses of bacteria expressing AqpZ and its FlAsH-tagged variant

StrainAqpZ variantkw (s−1)a
Upshock imposed with NaCl on culture from:Upshock imposed with proline on culture from:
Exponential phaseStationary phaseExponential phaseStationary phase
MG1655AqpZ6.82 ± 0.0519.24 ± 0.375.56 ± 0.0427.38 ± 0.63
NCM3306None6.02 ± 0.040.480 ± 0.0045.19 ± 0.030.350 ± 0.007
NCM3306/pBAD24None6.00 ± 0.070.450 ± 0.0045.09 ± 0.070.304 ± 0.008
NCM3306/pTR14AqpZ7.31 ± 0.1027.64 ± 0.407.18 ± 0.0617.89 ± 0.17
NCM3306/pTR15MVCCPGCC-AqpZ6.94 ± 0.090.984 ± 0.0055.37 ± 0.060.704 ± 0.005
NCM3306/pTR14bAqpZ7.08 ± 0.0629.19 ± 0.367.76 ± 0.0435.08 ± 0.31
NCM3306/pTR15bMVCCPGCC-AqpZ7.07 ± 0.0629.38 ± 0.517.95 ± 0.0329.38 ± 0.51
  • a Rate constants (kw) for the optical density change following osmotic upshocks (0.5 mol/kg) imposed on bacteria at 5°C were determined by stopped-flow light-scattering spectroscopy as described in Materials and Methods.

  • b Expression of aqpZ was induced with 1 mM arabinose for the last 2 h of growth.