The behavior of bacteria: on the mechanism of sensory transduction in bacterial chemotaxis.

The mechanism of bacterial chemotaxis is beginning to be understood. At the receptor end, we have considerable knowledge about the molecular properies of chemoreceptors. At the effector end, we know that flagella rotate and that the direction of rotation is determined by attractants and repellents, although we do not yet know the molecular features of the motor and the gear shift. Between the receptors and the effectors is a system for integrating the sensory information and transmitting a message to the flagella. This system, sensory transduction, somehow involves methylation of membrane proteins and probably a change in membrane potential, but further details of how the mechanism works remain to be elucidated.