Phosphorylation-dependent binding of a signal molecule to the flagellar switch of bacteria.
Regulation of the direction of flagellar rotation is central to the mechanism of bacterial chemotaxis. The transitions between counterclockwise and clockwise rotation are controlled by a "switch complex" composed of three proteins (FliG, FliM, and FliN) and located at the base of the flagellar motor. The mechanism of function of the switch is unknown. Here we demonstrate that the diffusible clockwise-signal molecule, the CheY protein, binds to the switch, that the primary docking site is FliM, that the extent of CheY binding to FliM is dependent upon the phosphorylation level of CheY, and that it is unaffected by the other two switch proteins. This study provides a biochemical demonstration of binding of a signal molecule to the bacterial switch and demonstrates directly that phosphorylation regulates the activity of this molecule.
Welch
M
M
Department of Membrane Research and Biophysics, Weizmann Institute of Science, Rehovot, Israel.
Oosawa
K
K
Aizawa
S
S
Eisenbach
M
M
D000577:Amides / Q000494:pharmacology; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D002633:Chemotaxis / Q000502:physiology*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005407:Flagella / Q000378:metabolism / Q000502:physiology*; D007700:Kinetics; D007930:Leucine / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D000072236:Methyl-Accepting Chemotaxis Proteins; D010755:Organophosphates / Q000494:pharmacology; D010756:Phosphoric Acids / Q000494:pharmacology; D010766:Phosphorylation; D011485:Protein Binding
D000577:Amides; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C077389:FliN protein, Bacteria; C075660:Flig protein, Bacteria; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D010755:Organophosphates; D010756:Phosphoric Acids; C000607606:cheY protein, E coli; C066821:FliM protein, Bacteria; C011632:acetyl phosphate; C011067:phosphoramidic acid; D007930:Leucine