RL211 antitermination assay
E. coli RL211 harbors the cat gene preceded by a
Rho-independent trpL terminator and is sensitive to
chloramphenicol (Cm). To test antitermination activity as described in
Ammerman et al. (72), Bae et al. (73), and Landick et al. (74), the
genes encoding StpA in the pET7C-HIS plasmid and PlzA, PlzA R145K and
PlzA R145D in pET-45b(+) plasmid were electroporated into E. coliRL211 strain provided by Dr. Robert Landick (74). Transformed RL211
strains were grown in either with 100 µg/ml ampicillin or 50 µg/ml
kanamycin overnight (OD600 0.9-1.0). Cultures were
spotted (5 µl) on LB plates with and without 34 µg/ml Cm. Cells were
grown for 1-3 d at 37°C. Plates were imaged in an Azure Sapphire imager.