Fig. 1: Robust polarity basis for constructing intracellular gradient and asymmetric division in E. coli.

a Graphical illustration of the regulatory layers for asymmetric gene expression and differentiation in E. coli. Two orthogonal mechanisms (x axis: PopZ from C. crescentus; y axis: DivIVA from B. subtilis) were introduced in E. coli to probe the essential features. Split RNA polymerases (N and C halves, shown in light and dark orange) were recruited to PopZ (shown in red) via PopZ-interacting proteins that served as adaptors (shown in blue). The gene expression product, DivIVA-sfGFP or DivIVA-sfGFP-AmpC (shown in green), was restrained from diffusion toward the mid cell and asymmetrically segregated at the first cell division. When two daughter cells were challenged with ampicillin, one cell survived and the other died. b Quantification of polarity metric for Anderson promoter series (“Methods”); n = 64, 160, 164, 134, and 155 cells for J23113, J23117, J23116, J23106, and J23100, respectively. Center line, median; box limits, upper and lower quartiles; whiskers, 1.5× interquartile range. c Time-lapse imaging of cells expressing mRFP-PopZ (top) and mRFP-PopZΔC (bottom) from the Anderson promoter J23116. Scale bars: 1 μm. d Quantification of mRFP-PopZ stability. mRFP-PopZ expression was induced from P_BAD with 2% arabinose for 24 h at 37 °C before time-lapse imaging. Fluorescence intensity was normalized by the maximal intensity. Dots, mean; Error bars, s.d. (n = 60 cells). Source data are provided as a Source Data file.