Receptor-mediated protein kinase activation and the mechanism of transmembrane signaling in bacterial chemotaxis. |
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| Authors: | Y Liu M Levit R Lurz M G Surette J B Stock |
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| Affiliation: | Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA. |
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| Abstract: | Chemotaxis responses of Escherichia coli and Salmonella are mediated by type I membrane receptors with N-terminal extracytoplasmic sensing domains connected by transmembrane helices to C-terminal signaling domains in the cytoplasm. Receptor signaling involves regulation of an associated protein kinase, CheA. Here we show that kinase activation by a soluble signaling domain construct involves the formation of a large complex, with approximately 14 receptor signaling domains per CheA dimer. Electron microscopic examination of these active complexes indicates a well defined bundle composed of numerous receptor filaments. Our findings suggest a mechanism for transmembrane signaling whereby stimulus-induced changes in lateral packing interactions within an array of receptor-sensing domains at the cell surface perturb an equilibrium between active and inactive receptor-kinase complexes within the cytoplasm. |
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