Ultrasensitive of the Bacillus subtilis sporulation decision

摘要

Sporulation of the bacterium Bacillus subtilis serves as a relatively simple model with which to study the differentiation of single cells; that is, how molecular networks monitor a range of internal and external signals and process them to make decisions affecting cell fate. Here, we have used a combination of synthetic biology, single-cell microscopy, and mathematical modeling to identify the cell fate decision point and the mechanism of decision making in the network that controls sporulation. Our results indicate a temporal separation between sporulation initiation and the final decision to sporulate. We also show that this decision is determined by the output of a cascade of feed-forward loops, which allow ultrasensitive (switch-like) signal processing without significant delays.