UCL Division of Biosciences



"Multiple input pathways mitigate speed-accuracy trade-offs in a MAP kinase signalling network "

Trade-offs limit an organism's capacity to respond to stress. Faster responses are, for example, typically less accurate. The signalling network in budding yeast that responds to hyperosmotic stress is Y-shaped with two pathways activating Hog1, a p38 MAP kinase. We determined that each pathway specializes to sensing stress with different dynamics: the Sln1 pathway increases fitness in sudden shocks whereas the other, Sho1, pathway increases fitness in ramping stress.  We argue that the two inputs mitigate a trade-off - speed is provided by the Sln1 branch and accuracy by the Slo1 branch - and, by converging on Hog1, the branches activate sequentially with the initial response dominated by the reflex-like Sln1 pathway.