FIG 4.

AphA regulates Asp expression via LuxR. (A) Western blot assay of LuxR expression with various concentrations of AphA (induced with l-arabinose). Bacterial cells of the ΔaphA strain harboring plasmid pBAD33::aphA-flag-2 were cultured in LBS medium for 9 h, harvested, and blotted with specific anti-Flag and anti-LuxR antibodies. (B) qRT-PCR analysis of the transcriptional level of aphA and luxR in the ΔaphA strain harboring pBAD33::aphA-flag-2 with different concentrations of l-arabinose. The bacterium was cultured in LBS for 9 h, and mRNA transcripts of aphA and luxR were detected by qRT-PCR. The 16S rRNA gene was selected as a control. The results are shown as means ± SD (n = 3). *, P < 0.05; **, P < 0.01; ***, P < 0.001 (Student's t test) compared to the value without addition of l-arabinose.