Signaling events that occur when cells of <i>Escherichia coli</i> encounter a glass surface
Alina M. Vrabioiu, Howard C. Berg
Abstract
that allowed us to visualize initial signaling events and assess the role played by the flagellar motor. The sensor was pH sensitive, and the events that appeared on a seconds' timescale were alkaline spikes in the intracellular pH. These spikes were not apparent when signals from different cells were averaged. Instead, a signal appeared on a minutes' timescale that proved to be due to an increase in intracellular c-di-GMP. This increase, but not the alkaline spikes, depended upon a functional flagellar motor. The kinetics and the amplitude of both the pH and c-di-GMP responses displayed cell-to-cell variability indicative of the distinct ways the cells approached and interacted with the surface. The energetic status of a cell can modulate these events. In particular, the alkaline spikes displayed an oscillatory behavior and the c-di-GMP increase was modest in the presence of glucose.