Fig. S1.

Northern blotting of RNA prepared from induced KD263 (Left) and KD546 (Right) cells. Total RNA was isolated from 5 mL of indicated E. coli cell cultures grown for 4 h after induction with 1 mM arabinose and 1 mM IPTG or in the absence of inducers. We separated 10 μg of total RNAs on a denaturing 8 M urea/15% (wt/vol) polyacrylamide gel and electrophoretically transferred it to the Hybond-XL membrane (GE Healthcare). ExpHyb hybridization solution (Clontech) was used for hybridization according to the manufacturer’s instructions for 1 h at 37 °C with ³²P-end–labeled, g8 spacer-specific probe (5′-GCGGGATCGTCACCCTCAGCAGCGAAAGACAG-3′, indicated as a blue leftward arrow) as described previously (27).