Dr. Armitage is interested in bacterial swimming behaviour, in particular the chemosensory pathway of Rhodobacter sphaeroides and the mechanism of action of the rotary bacterial flagellar motor. She and her lab were the first to identify that some species have multiple chemosensory pathways regulating swimming behaviour, something now shown to be common to most species. Using fluorescent fusion and a combination of in vitro and in vivo biochemistry, she showed that two of the chemosensory pathways are targeted to different regions of the cell, one polar with transmembrane receptors and the other cytoplasmic clustered with soluble receptors, something essential for function. A complex chemosensory signalling pathway balances signals from metabolism and the environment to control the flagella motor. The localisation and partitioning of the soluble chemosensory cluster uses a system related to the plasmid partitioning Par system.
Using optical tweezers and microfluidics Dr. Armitage's lab showed that the R.sphaeroides motor stops, using a brake, in response to a chemosensory signal. Using TIRF microscopy on flagellar motors she showed unexpectedly that the stator and rotor proteins of the rotary motor are dynamic, exchanging with pools of protein while the motor rotates.