The σB alternative sigma factor circuit modulates noise to generate different types of pulsing dynamics
Fig 5
The properties of the noise in the upstream pathways may bias the system towards either response behaviour.
(A,B) The amplitude (ηamp) and frequency (ηfreq) of the upstream pathway’s noise is varied. Plots show, for each parameter combination, the distinctness of the single response pulse (A) and stochastic pulsing (B) behaviours. The distinctness (of either behaviour) designates the system’s ability to uniquely generate that behaviour (and not the other behaviour) as a parameter is varied (here pprod). This measure is described in detail in Section 4.5.3 (there designated Dsrp or Dsp). Light green dots mark parameter sets optimising either behaviour’s distinctness. (C,D) For the parameter sets that maximise the distinctness of the single response pulse (C) and stochastic pulsing (D) behaviours, the magnitudes of the two behaviours are shown as functions of pprod. For each parameter set, 7 selected values of pprod are marked with grey lines. (E,F) For the 7 parameter sets marked in C (E), and D (F), a single simulation is displayed (stress added at t = 0, red dashed line). As pprod is varied, the two behaviours are generated much more robustly than what they were for the parameter set in Fig 4. Parameter values and other details on simulation conditions for this figure are described in S6 and S7 Tables.