Howard Berg
The motile behavior of bacteria

Flagellated bacteria possess a remarkable motility system based on a reversible rotary motor linked by a flexible coupling (the proximal hook) to a thin helical propeller (the flagellar filament). The motor derives its energy from protons driven into the cell by chemical gradients or electrical fields. The direction of the motor rotation depends in part on signals generated by sensory systems, of which the best studied analyzes chemical stimuli. Our research group is trying to learn how the motor works, the nature of the signal that controls the motor's direction of rotation and how this signal is processed by the chemical sensory system. The ultimate goal is an understanding of chemiosmotic coupling and sensory transduction at the molecular level. Specific areas of current interest include: interactions between proteins in the chemotaxis signal-transduction pathway as studied by FRET; sensitivity amplification by receptor clusters; signaling between receptors and flagellar rotary motors; force-generating and switching by flagellar motors; behavior of flagellar filaments, including polymorphic transformations; bacterial swarming motility; and gliding of Mycoplasma mobile.

Publications:
Berg, H.C. E. coli in Motion. (Springer, N.Y., 2004)

Berg, H.C. Random Walks in Biology. (Princeton: Princeton,1993).

Sourjik, V. and Berg, H.C. 2004. Functional interactions between receptors in bacterial chemotaxis. Nature 428: 437-441.

Vaknin, A. and Berg, H.C. 2004. Single-cell FRET imaging of phosphatase activity in the Escherichia coli chemotaxis system. PNAS 101: 17072-17077.