A receptor scaffold mediates stimulus-response coupling in bacterial chemotaxis

The mechanism of stimulus-response coupling in bacterial chemotaxis has eme rged as a paradigm for understanding general features of intracellular sign al transduction both in bacterial and eukaryotic cells. Until recently it w as thought that the mechanism involved reversible stochastic interactions b etween dimeric receptors freely diffusing in the cytoplasmic membrane and s everal soluble signal transduction proteins within the cytoplasm. Recent re sults have shown that this view is an oversimplification. The receptors and most of the signal transduction proteins are organized together in a highe r ordered structure at one pole of the bacterial cell. The scaffolding netw ork within this structure appears to be composed of C-terminal alpha-helica l extensions of the membrane chemoreceptor proteins held together in a latt ice by tandem SH3-like domains. Results suggest that stimuli are detected t hrough the perturbations they induce in scaffolding architecture. (C) Harco urt Publishers Ltd.