Figure 4

Split eGFP foci dynamism after ligand exposure. (A) Foci fluorescence of surface-immobilized E. coli ∆cheY∆cheZ (pCRO9) cells in wells with motility buffer or exposed to 100 µM NiCl₂ after time 2 min. Note that the t = 0 time point could not be measured due to mounting the slides. Blue curves indicate foci with less fluorescence decay than expected from the mean slope of all decay curves. (B) Proportion of deviant foci response curves compared to the mean slope of all foci decay curves in motility buffer ± one SD (*p = 0.0072). (C) Foci intensity distributions among surface-spread E. coli 5430 cells expressing unstable split-eGFP at three distances on a solid source with either 100 µM NiCl₂, 100 µM serine (SER), or motility buffer (MB) alone, each in two replicates. Note that distances are not differentiated here. Note the shift to brighter foci in Ni²⁺-exposed cells with values of 11–17 AGV (arrow). (D) Average proportion of foci per cell for the experiments in (C) as a function of position. Decreasing foci numbers as a function of distance (pos3 to pos1) for serine-exposed cells is statistically significant (LINEST slope test, p = 0.0034), whereas those in cells exposed to Ni²⁺ or in MB do not differ significantly from the Null hypothesis (Slope = 0).