A linkage between variability in EI localization and phenotypic heterogeneity in sugar utilization as well as antibiotic persistence

Although the list of proteins that localize to the bacterial cell poles is constantly growing, little is known about their temporal behavior. EI, a major protein of the phosphotransferase system (PTS) that regulates sugar uptake and metabolism in bacteria, was shown to form clusters at the Escherichia coli cell poles. By monitoring EI distribution between clusters and diffuse molecules during the lifetime of E. coli cells, we found that EI spatiotemporal localization differs among cells in a population. In growing cells, EI is not assembled into clusters in almost 40% of the cells. In non-growing cells, the fraction of cells that contain EI clusters is significantly higher, and dispersal of these clusters is often observed shortly after exiting quiescence. Using a fluorescent glucose analog, we found that EI function inversely correlates with clustering and with cluster size. Thus, activity is exerted by dispersed EI molecules, whereas the polar clusters serve as a reservoir of molecules ready to act when needed. Preliminary results show that cells deleted for EI-localizing factor, TmaR, in which EI is completely diffused, exhibit a significantly lower rate of spontaneous persistence to antibiotics compared to wild type cells. These results suggest a mechanism for the generation of spontaneous persisters. Taken together our findings highlight the spatiotemporal distribution of EI as a novel layer of regulation that contributes to the population phenotypic heterogeneity with regard to sugar metabolism and antibiotic persistence, seemingly conferring a survival benefit.