Transmembrane signaling in bacterial chemoreceptors

Bacterial chemoreceptors mediate chemotaxis by recognizing specific chemicals and regulating a noncovalently associated histidine kinase, Ligand binding to the external domain of the membrane-spanning receptor generates a transmembrane signal that modulates kinase activity inside the cell. This transmembrane signaling is being investigated by novel strategies,which have revealed a remarkably subtle conformational signal carried by a signaling helix that spans the entire length of the > 350-Angstrom -long receptor. Multiple, independent lines of evidence indicate that, in the periplasmic a nd transmembrane domains, conformational signaling is a piston-type sliding of the signaling helix towards the cytoplasm.