Robust amplification in adaptive signal transduction networks

Amplification of small changes in input signals is an essential feature of many biological signal transduction systems. An important problem is haw se nsitivity amplification can be reconciled with wide dynamic range of respon se. Here a general molecular mechanism is proposed, in which both high ampl ification and wide dynamic range of a sensory system is obtained, and this without fine-tuning of biochemical parameters. The amplification mechanism is based on inhibition of the enzymatic activity of the sensory complex. As an example, we show how this 'inhibition-driven amplification' mechanism m ight function in the bacterial chemotaxis network, where it could explain s everal intriguing experimental observations connected with the existence of high gain, wide dynamic range and robust adaptation. (C) 2001 Academie des sciences/Editions scientifiques et medicales Elsevier SAS.