Fig. 2.
Effect of BumR receiver domain mutations on butyrate-modulated transcription. (A) Production of BumR in WT C. jejuni and bumR mutants. Immunoblot analysis of the level of BumR in whole-cell lysates of WT and mutant strains after growth in Mueller–Hinton media. RpoA served as a control for protein loading. (B) qRT-PCR analysis of peb3 transcription in WT C. jejuni and bumR mutants grown in CDM alone or CDM supplemented with 12.5 mM butyrate. The expression of peb3 in CDM alone (solid blue bars) and CDM with butyrate (hatched blue bars) in WT C. jejuni and mutant strains are shown. The level of peb3 transcription in WT grown in CDM alone as measured by qRT-PCR was set to 1. Expression of peb3 in WT grown in CDM with butyrate or mutants grown with or without butyrate is shown relative to the WT strain grown in CDM alone. Results from a representative assay with each sample analyzed in triplicate are shown. Error bars indicate SDs of the average level of expression from three samples. Statistical significance of ΔCT values relative to secD reference gene was calculated in GraphPad Prism by ANOVA with Tukey’s test: * indicates the mutant grown in CDM alone had significantly increased or decreased expression relative to the WT strain grown in CDM alone; ** indicates the mutant grown with butyrate had a significantly increased or decreased expression relative to the WT strain grown with butyrate; *** indicates a strain showed a significantly different level of expression when grown in the presence of butyrate compared to growth in CDM alone (P < 0.05).