Figure 2. Construction of LLPS-based compartment in E.
coli.
A. Illustration of PhASE#1 phase module design.FUSLCD can phase separate in vivo , while GCN4 can further
facilitate it. CIB1 is one of the two members in the light-responsive
protein pair. See Figure 3A for further explanation.B. Illustration of the mechanism behind compartment
construction. As its concentration rises beyond a threshold, the phase
module will self-aggregate into membraneless compartments with a unique
chemical environment. C, D. The process of compartment
formation in E. coli. Most compartments nucleated around cell
poles and could move around (C). Some aggregates emerged elsewhere,
moved towards an end of the bacteria cell, and finally fused with other
condensates (D). Scale bar, 1 μm. E. Homogeneous compartment
formation in E. coli. Almost every bacterium contains
compartments localized at their poles, when expressing PhASE#1 phase
module. Phase module was under T7 promoter controlled by lacO .
Either 0.25 mM or 1 mM IPTG was added to induce its expression. For more
IPTG concentration gradients, please refer to Supplementary Figure 1.
Scale bar, 2.5 μm. F. Fluidity of PhASE#1 phase modulein vivo. Fluorescence Recovery After Photo-bleaching (FRAP) was
used to characterize the fluidity of the fusion protein. The recovery of
fluorescence could be due to rapid protein exchange with the surrounding
cytoplasm. The fluorescence signal of the highlighted condensate was
normalized to that on the other side of the bacterium. Scale bar, 1 μm.