Role of CheW protein in coupling membrane receptors to the intracellular signaling system of bacterial chemotaxis.
Chemotactic behavior in Escherichia coli is mediated by membrane-associated chemoreceptors that transmit sensory signals to the flagellar motors through an intracellular signaling system, which appears to involve a protein phosphorylation cascade. This study concerns the role of CheW, a cytoplasmic protein, in coupling methyl-accepting chemotaxis proteins (MCPs), the major class of membrane receptors, to the intracellular signaling system. Steady-state flagellar rotation behavior was examined in a series of strains with different combinations and relative amounts of CheW, MCPs, and other signaling components. At normal expression levels, CheW stimulated clockwise rotation, and receptors appeared to enhance this stimulatory effect. At high expression levels, MCPs inhibited clockwise rotation, and CheW appeared to augment this inhibitory effect. Since overexpression of CheW or MCP molecules had the same behavioral effect as their absence, chemoreceptors probably use CheW to modulate two distinct signals, one that stimulates and one that inhibits the intracellular phosphorylation cascade.
Liu
J D
JD
Biology Department, University of Utah, Salt Lake City 84112.
Parkinson
J S
JS
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002630:Chemotactic Factors / Q000378:metabolism*; D002633:Chemotaxis; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D008565:Membrane Proteins / Q000378:metabolism; D000072236:Methyl-Accepting Chemotaxis Proteins; D008962:Models, Theoretical; D015183:Restriction Mapping; D015398:Signal Transduction
D001426:Bacterial Proteins; C489103:CheW protein, E coli; D002630:Chemotactic Factors; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C051236:CheW protein, Bacteria