Figure 8.

Competence regulation in B. subtilis Süel et al. (2006); Süel et al. (2007): (a) Gene circuit controlling competence master regulator protein ComK include a positive feedback loop of autocatalytic synthesis of ComK and negative feedback loop where ComK inhibits synthesis of ComS protein that in turn inhibits degradation of ComK by the ClpP-ClpC-MecA protease complex. (b) phase plane of the model (20) with nullclines (thick solid lines), the vector field (gray arrows) and the stochastic trajectory (thin solid line) showing bursts of competence; (c)the probability of competence initiation P_int grows with the basal expression rate of comK gene (α_k, red squares), but is only weakly dependent on the comS expression rate α_s (green triangles); (d) Conversely, the duration of the competent state increases with α_s but is weakly dependent on α_k; (e) Increasing cell size (that putatively reduces intrinsic noise) reduces P_int.