A bacterial cell has many different two component systems(TCSs)that allow it to sense and adapt to various environmental stimulations,such as temperature,oxygen concentration,degree of acidity and alkalinity[1].Each TCS is composed of a sensor histidine kinase(HK)and a response regulator(RR)[2,3].To investigate TCSs in a systematical way,we built light-sensing TCSs in E.coli by reengineering wild-type HKs.A modified HK
