The bacterial chemotaxis adaptor protein CheW physically links the chemoreceptors (MCPs) and the histidine kinase CheA. Extensive investigations using bacterium Escherichia coli have established the central role of CheW in the MCP-modulated activation of CheA. Here we report the solution structure of CheW from E. coli determined by NMR spectroscopy. The results show that E. coli CheW shares an overall fold with previously reported structure of CheW from Thermotoga maritima, whereas local conformational deviations are observed. In particular, the C-terminal alpha-helix is considerably longer in E. coli CheW and appears to shrink the active binding pocket with CheA. Our study provides the structural basis for further investigations in E. coli chemotaxis. (c) 2007 Elsevier Inc. All rights reserved.