Strain O395VieAΔHTH-FLAG expressing a chromosomally-integrated allele encoding VieAΔHTH-FLAG was transformed with plasmid pBAD33 or pBADLeuO-6xHis. Triplicate cultures of each transformants were grown in LB medium to stationary phase and the expression of VieAΔHTH-FLAG, LeuO-6xHis and TcpA was determined by western blot as described in materials and methods. Lane a, O395VieAΔHTH-FLAG containing pBAD33; lane b, O395VieAΔHTH-FLAG containing pBADLeuO-6xHis grown in LB medium; lane c, O395VieAΔHTH-FLAG containing pBADLeuO-6xHis grown in LB supplemented with L-arabinose (0.02 %). Quantitation of VieAΔHTH-FLAG expression by densitometry is shown at the bottom of the figure (mean band volume ± STDEV, n = 3).