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. Author manuscript; available in PMC: 2019 Feb 1.
Published in final edited form as: Mol Microbiol. 2017 Dec 11;107(3):330–343. doi: 10.1111/mmi.13884

Fig. 1. LeuO represses vieSAB transcription.

Fig. 1

A. Strains O395ΔlacZ (classical biotype, Cl) and C7258ΔlacZ (EL Tor biotype, ET) (□, open bars) and their isogenic ΔleuO mutants (■, filled bars) containing a vieSAB-lacZ promoter fusion were grown to stationary phase in LB medium B. Strain O395ΔlacZ (Wt) and its Δhns mutant containing a vieSAB-lacZ promoter fusion were transformed with pBAD33 (□, open bar) or pBAD-LeuO (■, filled bar) and grown to stationary phase in the presence of L-arabinose (0.2 %). Panels C and D. Strain O395ΔlacZ containing a vieSAB-lacZ promoter fusion was transformed with plasmid pBAD-LeuO (C) or pBAD33 (D). Strains were grown to mid-exponential phase and the cultures divided in halves. In one half, LeuO expression was induced by addition of L-arabinose (0.2 %) (■, filled bars) and the remaining half was used as a control (□, open bars). E. El Tor biotype strains AJB80 (Δhns) and AJB51ΔlacZ (ΔhapR) containing a vieSAB-lacZ promoter fusion were transformed with pBAD33 (□, open bar) or pBAD-LeuO (■, filled bar) and grown to stationary phase in the presence of L-arabinose (0.02 %). β-galactosidase activity (Miller units) was measured as an indicator of promoter activity. The error bars denote the standard deviation of at least three independent transformants. Symbols: * p < 0.05; ** p < 0.01 (unpaired T test).