Bacterial Chemotaxis: Rising Complexity

Bacterial chemotaxis is a paradigm for biological sensing and information transmission. The chemotaxis signal-transduction pathway allows cells to sense chemicals in their surroundings in order to regulate flagellated rotary motors, thus allowing them to swim towards nutrients and away from toxins. Importantly, cells are able to sense with remarkably high sensitivity over a wide range of chemical background concentrations. To make this possible, chemoreceptors do not signal independently but form clusters for amplification and integration of signals, as well as for adaptation to persistent stimulation. While chemotaxis in Escherichia coli has been exceptionally well characterized, new experimental facts still require revisions of existing models and thus further increase our understanding of sensing and signalling in bacteria. Additionally, experiments on other bacterial species such as Bacillus subtilis and Rhodobacter sphaeroides indicate that bacteria other than E. coli can have substantially different and more complex chemotaxis pathways, which provides renewed challenges for experimentalists and modellers alike. Here we discuss our current understanding as well as the frontiers of bacterial chemotaxis research.