Effects of Signalling on the Evolution of Gene Regulatory Networks

We investigate whether observed transcription network structures and network motifs are a byproduct of the mechanisms by which DNA strands evolve, or if they are fundamental to the function of the network. We explore this with an evolutionary model with stochastic Boolean network simulation. Structurally distinct regulation strategies are observed in populations evolved with and without internal energy signalling. However, food signalling is not used in either population in the case when the food supply itself is constant. Parallels between the evolved networks and CRP-cAMP regulation inEscherichia coli and the endosymbiont Buchnera aphidcola are presented and discussed. Comparing the evolved networks with neutrally evolved populations indicates that networks evolve to lose most regulatory activity, due to loss of binding sites and transcription factor activity, including losing global regulation mechanisms.