Fig 4. Effect of FA and pHBA on gene transcription within fusR-bucl8-fusCD-fusE operon.

(A) Growth curves of B. pseudomallei strain Bp82 and B. mallei strain CLH001. Cultures were grown in strain-specific broth and optical density (O.D.) and colony forming units (CFU) were recorded. Dotted line represents OD of 0.4. Error bars represent ±SEM. (B-D) RT-qPCR was performed on RNA samples isolated from cultures of the indicated strain, untreated and treated with substrate, at an OD₆₀₀ of ~0.4 for 1 hour. Graph shows fold change of relative gene expression compared to untreated cultures and normalized to transcription of 16S rRNA gene. Technical and experimental replicates were done in triplicate. One-way ANOVA with Tukey’s multiple comparison test of the log10 –transformed fold change. Significance shown is in comparison to tar; ***p < 0.001. Error bars represent ±SEM. (B) Transcription activation of fusR-bucl8-fusCD-fusE genes in Bp82 with 1000 μM FA. The downstream tar gene is assumed outside of the fusR-bucl8 operon. (C) Transcription activation of fusR and bucl8 in CLH001 with 60 μM FA. (D) Transcription activation of Bucl8 regulon in Bp82 with 6.25 mM pHBA.