Organization of the receptor-kinase signaling array that regulates Escherichia coli chemotaxis.
Motor behavior in prokaryotes is regulated by a phosphorelay network involving a histidine protein kinase, CheA, whose activity is controlled by a family of Type I membrane receptors. In a typical Escherichia coli cell, several thousand receptors are organized together with CheA and an Src homology 3-like protein, CheW, into complexes that tend to be localized at the cell poles. We found that these complexes have at least 6 receptors per CheA. CheW is not required for CheA binding to receptors, but is essential for kinase activation. The kinase activity per mole of bound CheA is proportional to the total bound CheW. Similar results were obtained with the E. coli serine receptor, Tsr, and the Salmonella typhimurium aspartate receptor, Tar. In the case of Tsr, under conditions optimal for kinase activation, the ratio of subunits in complexes is approximately 6 Tsr:4 CheW:1 CheA. Our results indicate that information from numerous receptors is integrated to control the activity of a relatively small number of kinase molecules.
Levit
Mikhail N
MN
Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA.
Grebe
Thorsten W
TW
Stock
Jeffry B
JB
D001426:Bacterial Proteins / Q000378:metabolism*; D002628:Chemoreceptor Cells; D002633:Chemotaxis; D003593:Cytoplasm / Q000378:metabolism; D003720:Densitometry; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism / Q000648:ultrastructure*; D029968:Escherichia coli Proteins / Q000378:metabolism; D000071677:Histidine Kinase; D007700:Kinetics; D008024:Ligands; D008565:Membrane Proteins / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D008954:Models, Biological; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000378:metabolism; D012486:Salmonella typhimurium / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors
D001426:Bacterial Proteins; C489103:CheW protein, E coli; D029968:Escherichia coli Proteins; D008024:Ligands; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D011956:Receptors, Cell Surface; C057331:Tar protein, E coli; C057635:Tsr protein, Bacteria; C000607604:tsr protein, E coli; C051236:CheW protein, Bacteria; D000071677:Histidine Kinase; C000607608:cheA protein, E coli