Receptor-mediated protein kinase activation and the mechanism of transmembrane signaling in bacterial chemotaxis.
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.
Liu
Y
Y
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
Levit
M
M
Lurz
R
R
Surette
M G
MG
Stock
J B
JB
D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D002462:Cell Membrane / Q000502:physiology; D002633:Chemotaxis / Q000502:physiology*; D019281:Dimerization; D004789:Enzyme Activation; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins; D000071677:Histidine Kinase; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D000072236:Methyl-Accepting Chemotaxis Proteins; D008958:Models, Molecular; D011494:Protein Kinases / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000502:physiology*; D015398:Signal Transduction
D001426:Bacterial Proteins; C489103:CheW protein, E coli; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C051236:CheW protein, Bacteria; D011494:Protein Kinases; D000071677:Histidine Kinase; C000607608:cheA protein, E coli