Molecular composition of functional microdomains in bacterial membranes

Membranes of eukaryotic cells organize a number of proteins related to signal transduction and membrane trafficking into microdomains, which are enriched in particular lipids, like cholesterol and sphingolipids and are commonly referred as to lipid rafts or membrane rafts. The existence of this type of signaling platforms was traditionally associated with eukaryotic membranes because prokaryotic cells were considered too simple organisms to require a sophisticated organization of their signaling networks. However, the research that have been performed during last years have shown that bacteria organize many signaling transduction processes in Functional Membrane Microdomains (FMMs), which are similar to the lipid rafts that are found in eukaryotic cells. The current knowledge of the existence of FMMs in bacteria is described in this review and the specific structural and biological properties of these membrane microdomains are introduced. The organization of FMMs in bacterial membranes reveals an unexpected level of sophistication in signaling transduction and membrane organization that is unprecedented in bacteria, suggesting that bacteria as more complex organisms than previously considered.