Professor Judith Armitage FRS, Department of Biochemistry, University of Oxford
Monday 24th February, 4.00 p.m., Marlowe Lecture Theatre 1
Most bacteria swim. Swimming motility is driven by a helical flagellum rotated at up to 1300rev/sec at its base by a transmembrane ion driven rotary motor. The motor can rotate clockwise or counter-clockwise and changes in switching frequency biases the overall swimming pattern of the bacterium towards an optimum environment for growth.
Structural and cryo electron microscopy studies suggested the motor resembles a tiny electric motor, but our in vivo studies have shown that the motor is a dynamic nanomachine, with protein subunits exchanging with pools of protein as the rotor spins. In the bacterium R. sphaeroides motor switching is controlled by two chemosensory pathways. The proteins of one pathway localise with transmembrane chemoreceptors into membrane patches, while the other pathway localises in the cytoplasm to midcell with soluble chemoreceptors. On division each daughter cell must inherit a membrane and a soluble complex to allow chemotaxis. Using a combination of molecular genetics, biochemistry and fluorescent imaging we have developed a spatio-temporal model for protein localisation and segregation through the cell cycle and enroute identified a novel mechanism for proteins to piggy-back on segregating chromosomes.