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 sensitivity amplification can be reconciled with wide dynamic range of response. Here a general molecular mechanism is proposed, in which both high amplification 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 might function in the bacterial chemotaxis network, where it could explain several 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.