Howard C. Berg
Department of Molecular and Cellular Biology
Harvard University
Biological Laboratories 351
16 Divinity Avenue
Cambridge, MA 02138
tel: (617) 495-0924 fax: (617) 496-1114
email: hberg@biosun.harvard.edu
Bacterial Motility and Behavior
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 rotation of the motor depends, in part, on signals generated
by sensory systems, the best studied of which analyzes chemical stimuli.
Professor Berg's group is trying to learn how the motor works, what the
signal is that controls its direction of rotation, and how this signal
is processed by the chemical sensory system. These questions are being
approached by a variety of molecular-genetic and physical techniques. The
goal is an understanding of chemiosmotic coupling and sensory transduction
at the molecular level. Other works in progress includes studies of the
motility of a bacterium that swims without flagella, development of a holographic
interference microscope, and measurement of the progression of enzymes
that move along DNA.
Selected Publications:
Scharf, B.E., Fahrner, K.A., Turner, L. and Berg, H.C. Control
of direction of flagellar rotation in bacterial chemotaxis. Proc. Natl.
Acad. Sci. USA 95:201-206 (1998).
Scharf, B.E., Fahrner, K.A. and Berg, H.C. CheZ has no effect on flagellar
motors activated by CheY13DK106YW. J. Bacteriol. 180: 5123-5128 (1998).
Berry, R.M. and Berg, H.C. Torque generated by the flagellar motor
of Escherichia coli while driven backwards. Biophys. J. 76:580-587
(1999).