Fig. 7.

Importance of the chaperones ProQ (A) and Hfq (B) in SraL–rho regulation. (A and B) Total cellular RNA was extracted from the S. Typhimurium strains, grown in LB at 37 °C until an OD₆₀₀ of 1. (Upper) The rho mRNA expression level was determined by Northern blot using 20 μg of total RNA separated in a 1.3% formaldehyde/agarose gel. The amount of RNA in wild type was set as one. The ratio between the RNA amount of each strain and wild type is represented below each strain (relative levels); 16S rRNA was used as loading control. (Lower) Thirty micrograms of total RNA were separated in a 6% PAA/8.3 M urea to determine the expression level of SraL sRNA; 5S rRNA was used as loading control. A representative membrane is shown, and values indicated correspond to the average of several Northern blot experiments with RNAs from at least two independent extractions. Dashed lines indicate noncontiguous lanes.