Fig. 1: Effects of JT71 on MrkH-mediated transcription and bacterial growth.

a Chemical structure of JT71. b Luminescence-based β-galactosidase screen of E. coli MC4100 containing either pMUmrkA-lacZ and pACYC184-mrkH (test plate) or pMUaap-lacZ and pACYC184-aggR (control plate), following treatment with ChemBridge library compounds. The activity of the hit compound JT71 was assessed relative to G771, a representative non-inhibitory compound on the same plate, while B371 represents a false positive that inhibited both reporters. Data shown are single measurements from the primary screen. c β-galactosidase activity from the mrkA promoter reporter in K. pneumoniae ΔlacZ in the presence of 50 µM JT71 or 1% DMSO. Activity from the mtr-lacZ control promoter is shown in parallel. Symbols represent biological replicates pooled from three independent assays; horizontal lines indicate the mean. Statistical analysis was performed using an unpaired two-tailed t test. d qRT-PCR analysis of K. pneumoniae AJ218 grown in the presence of 50 µM JT71 or 1% DMSO. Transcript levels of mrkA and mrkH were quantified and normalised to rpoD. Expression values are presented as fold change relative to the DMSO control. Horizontal bars indicate the mean ± SD of three biological replicates. Statistical analysis was performed using an unpaired two-tailed t test. e Static growth of K. pneumoniae AJ218 (OD₆₀₀) over 6 hours in M63 media containing 50 µM JT71 or 1% DMSO. Data are shown as the mean ± SD from three independent assays.