How does the polar flagellate Campylobacter jejuni swim?

Many bacteria need to swim to cause diseases ranging from food poisoning to cholera. Understanding how they swim is essential for the development of therapeutics to block these diseases. Most bacteria swim using helical propellers called flagella that are rotated by molecular motors embedded in the cell surface. Although understanding flagellar motility has focused on the flagella of Escherichia coil and Salmonella enterica, whose flagella are dotted over their cell surface, many bacteria polarly-localize their flagella. These polarly-localised flagella and their molecular motors are considerably more complex than those of E. coli and Salmonella. This proposal seeks to understand the functional implications of the differences between polar and non-polar flagella. Our core techniques are bacterial genetics (which we can use to alter various characteristics of flagella) and electron cryo-microscopy (which we can use to directly visualise molecular structures so we can understand the underlying mechanisms of swimming changes from our genetic changes), which we will augment with other techniques through a stable of long-term established collaborations. We will focus on our model for polar flagellation, Campylobacter jejuni, because we can easily make genetic alterations to change key flagellar characterstics, and it is well-suited for the techniques we will use.