Fig. 3.

Noncognate HSL AIs with chain lengths of C8 or longer, and the synthetic compound mBTL, inhibit LuxR_ARM81ld activity. (A) General structure of an HSL AI (R = O or H; n = 0, 2, 4, 6, or 8) and the structure of the synthetic compound mBTL. (B) PsmORF_ARM81ld-lux expression from E. coli carrying aTc-inducible xre_ARM81ld-luxR_ARM81ld grown in a medium containing aTc supplemented with DMSO or the indicated compounds or in a medium lacking aTc (No induction). HSL concentrations as in Fig. 2C. (C) PsmORF_ARM81ld-lux expression from E. coli carrying aTc-inducible xre_ARM81ld-luxR_ARM81ld grown in a medium containing aTc and the indicated concentrations of C4-HSL and C8-HSL. Data are shown as a heatmap. Normalized RLU refers to the RLU of each sample relative to the RLU of the sample administered DMSO only, which was set to 1.0. Data are represented as mean ± SD with n = 3 biological replicates (B) or as mean with n = 2 biological replicates (C). RLU as in Fig. 1B (B, C). aTc; 25 ng mL⁻¹ (B, C).