Adaptive circuits in synthetic biology

One of the most remarkable features of biological systems is their ability to adapt to the constantly changing environment. By harnessing principles of control theory, synthetic biologists are starting to mimic this adaptation in regulatory gene circuits. Doing so allows for the construction of systems that perform reliably under non-optimal conditions. Furthermore, making a system adaptive can make up for imperfect knowledge of the underlying biology and, hence, avoid unforeseen complications in the implementation. Here, we review recent developments in the analysis and implementation of adaptive regulatory networks in synthetic biology with a particular focus on genetic circuits that can realize perfect adaptation.