Generation of cell polarity is an intriguing event and one of the least understood processes in biology. Although the poles of rod-shaped bacterial cells emerge as hubs for important activities1, the cues and mechanisms that underlie polar localization of proteins are largely unknown.
The "control center" of the PTS - the central bacterial system that controls hierarchal sugar consumption - which consists of EI and HPr, has been shown by us to cluster at the cell poles2. We then asked: how are these proteins targeted specifically to the cell poles? Using a series of mutants defective in cytoskeletal, cell wall and cell division genes, we demonstrated that the PTS proteins localize to negatively curved membrane regions at the poles in a way that maintains their activity3. Localization of EI to negative curved membrane domains was found to be conserved across bacterial species. Our data excluded the possibility that the soluble PTS proteins recognize the membrane, suggesting that other factors target and anchor them to the pole.
Using a genetic screen, we identified several proteins, previously not known to be involved in polar localization of proteins, which target and/or anchor EI to the poles. Several of the newly identified proteins localize to the poles and recognize negatively curved membrane regions. We are currently investigating whether these factors are involved in polarity-establishment. Our findings highlight membrane geometry as an ancient cell-organizing mechanism.
1 Amster-Choder O. (2011). Cell Logist
2 Lopian et al. (2010) EMBO J.
3 Govindarajan, Elisha et al. (2013) MBio
