Figure 3.

Increased levels of the RNA CrcZ result in upregulation of phzM translation. (A) Strain PAO1 (pME10011) was grown in BSM supplemented with 5 mM succinate and 40 mM mannitol. The β-galactosidase activity conferred by the translational phzM::lacZ reporter gene was determined at T1 and T3 (see Figure 1A), respectively. The corresponding steady state levels of the CrcZ RNA are shown in Figure 1B. (B) Increased phzM::lacZ translation during growth in BSM supplemented with mannitol. The synthesis of the PhzM-LacZ protein was assessed in strain PAO1 (pME10011) by monitoring the β-galactosidase activity after growth to an OD₆₀₀ of 2.0 in BSM medium supplemented with succinate (Suc) and mannitol (Man), respectively. (C) Increased phzM::lacZ translation upon ectopic expression of the crcZ gene from plasmid pMMBcrcZ. The synthesis of the PhzM-LacZ protein was assessed in strains PAO1 (pME10011; pMMB67HE) and PAO1 (pME10011; pMMBcrcZ) by monitoring the β-galactosidase activity after growth to an OD₆₀₀ of 2.0 in BSM medium supplemented with succinate. The error bars represent SDs. Top panels (B,C). The steady state levels of the CrcZ RNA were determined by Northern-blot analysis when the cultures reached an OD₆₀₀ of 2.0. 5S rRNA served as a loading control.