Fig. 1
From: Chemotaxis of Escherichia coli to major hormones and polyamines present in human gut
FRET-based analysis of the chemotaxis pathway response to catecholamines. a, c, e Examples of FRET measurements of responses to dopamine (a), norepinephrine (NE) (c), and 3,4-dihydroxymandelic acid (DHMA) (e). The ratio of YFP/CFP fluorescence reflects the efficiency of FRET and thus activity of the chemotaxis pathway. Buffer-adapted cells were stimulated with step-like addition and subsequent removal of compounds, indicated by downward and upward arrows, respectively. Saturating stimulation with 1 mM α-methyl-DL-aspartate (MeAsp) was used as a positive control. b, d, f Dose-response curves of wild-type cells (filled circles), Tar-only cells (open squares) or Tsr-only cells (open diamonds) to dopamine (b), NE (d), and DHMA (f). Each point represents the mean FRET-measured values of the kinase activity, normalized to the activity in buffer, from at least three independent experiments, with error bars indicating the standard error of the mean. Values above one correspond to a repellent response, while values below one correspond to an attractant response
