The chemotaxis pathway of the bacterium
Rhodobacter sphaeroides
shares many similarities with that of
Escherichia coli
. It exhibits robust adaptation and has several homologues of the latter's chemotaxis proteins. Recent theoretical results have correctly predicted that the
E. coli
output behaviour is unchanged under scaling of its ligand input signal; this property is known as fold-change detection (FCD). In the light of recent experimental results suggesting that
R. sphaeroides
may also show FCD, we present theoretical assumptions on the
R. sphaeroides
chemosensory dynamics that can be shown to yield FCD behaviour. Furthermore, it is shown that these assumptions make FCD a property of this system that is robust to structural and parametric variations in the chemotaxis pathway, in agreement with experimental results. We construct and examine models of the full chemotaxis pathway that satisfy these assumptions and reproduce experimental time-series data from earlier studies. We then propose experiments in which models satisfying our theoretical assumptions predict robust FCD behaviour where earlier models do not. In this way, we illustrate how
transient dynamic phenotypes
such as FCD can be used for the purposes of discriminating between models that reproduce the same experimental time-series data.
Automatic network reconstruction from experimental time-series data: A survey
