Armitage Group University of Oxford

Professor Judy Armitage Dr. George Wadhams  University of Oxford
Localisation of chemotaxis proteins in the bacterium Rhodobacter sphaeroides

Chemotaxis is the process by which bacteria move towards or away from chemical stimuli in their environments and has been implicated in bacterial pathogenesis,
symbiosis and biofilm formation. The signalling pathway for chemotaxis has been studied extensively in Escherichia coli, however many other bacterial species have
been shown to contain multiple homologous signalling pathways. The chemotaxis proteins in E. coli are assembled into a large multi-protein complex at the pole of the cell.
This clustering of the proteins has been implicated in the dramatic signal amplification and gain seen in the chemotaxis signalling pathway.

Rhodobacter sphaeroides is a prime example of a bacterium with more complex chemotaxis signalling systems.
We have utilised genomic replacements of chemotaxis genes with their corresponding GFP-fusions to show that
R. sphaeroides contains at least two functional complexes of chemotaxis signalling proteins which are spatially
separated within the bacterial cell. Interestingly, the proteins required for the correct assembly of these two
complexes differ.

We have also found a novel protein encoded within one of the chemotaxis operons which appears to be involved
in the correct positioning and segregation of these protein complexes on cell division. These data have profound
implications not only for our understanding of the process of bacterial chemotaxis, but also contradicts the
traditional view of the bacterial cytoplasm as being a homogeneous “soup” of protein and DNA constituents.










System Configuration
SPCI Core and Capture Software
Dynamic Intensity Analysis Software
Hamamatsu ORCA-ER Camera
P.I. Piezo Z Scanner
Nikon TE200 Inverted Microscope