Bacterial motility

Swimming with fluorescent flagella

Swimming without flagella




Carpets and microchannels

The chemotaxis system

Fluorescent chemotaxis proteins

Signaling studied by FRET and BRET


Adaptation at the output

The flagellar motor

Motor force generation

Switching under load

Adaptation to changes in load

The flagellar filament

Visualization of the filament

Visualizing flagella of tracked bacteria

Rowland Institute         Harvard University

Projects in the Berg group

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. These questions are being approached by a variety of molecular-genetic and physical techniques. The goal is an understanding of flagellar motility and sensory transduction at the molecular level. Recent work has shown that bacterial gliding also is powered by rotary motors. We hope to learn how rotation is linked to translation. Could we be dealing with sprockets and chains or pinions and racks?!