Fig 2.

Measurements of light production of promoter-luciferase fusions in C. jejuni and E. coli. The racR and dnaJ transcriptional regulatory sequences were subcloned in front of the luxCDABE operon in pRY112, and the vector was transformed into wt C. jejuni and the ΔracR and ΔracS mutants. Measurements were made for the first 12 h of bacterial growth. Light counts per second (CPS) were normalized to the OD₆₀₀ at the time of measurement. (A and B) Data for P_racR-luxCDABE (A) and P_dnaJ-luxCDABE (B) in wt C. jejuni and the ΔracR and ΔracS mutants are shown. Data are averages of data from 4 independent cultures, and standard deviations are denoted by error bars. (C) Map of the pRY112-derived vector utilized to investigate RacR-dependent transcriptional regulation in E. coli. The luciferase operon was fused to P_dnaJ in a plasmid with racR under the transcriptional regulation of the arabinose-inducible P_BAD promoter. The transcriptional expression of araC was under regulation of the constitutive promoter (P_c). (D) Light produced by E. coli cultures carrying theP_dnaJ-luxCDABE/araC or P_dnaJ-luxCDABE/araC/P_BAD-racR vector in the presence (+) or absence (−) of arabinose. Error bars denote standard deviations. ns, not significant.