Phosphorylation-independent bacterial chemoresponses correlate with changes in the cytoplasmic level of fumarate.
Bacterial chemotaxis is based on modulation of the probability to switch the direction of flagellar rotation. Responses to many stimuli are transduced by a two-component system via reversible phosphorylation of CheY, a small cytoplasmic protein that directly interacts with the switch complex at the flagellar motor. We found that the chemorepellents indole and benzoate induce motor switching in Escherichia coli cells with a disabled phosphorylation cascade. This phosphorylation-independent chemoresponse is explained by reversible inhibition of fumarase by indole or benzoate which leads to an increased level of cellular fumarate, a compound involved in motor switching for bacteria and archaea. Genetic deletion of fumarase increased the intracellular concentration of fumarate and enhanced the switching frequency of the flagellar motors irrespective of the presence or absence of the phosphorylation cascade. These correlations provide evidence for fumarate-dependent metabolic signal transduction in bacterial chemosensing.
Montrone
M
M
Max-Planck-Institut fur Biochemie, Martinsried, Germany.
Oesterhelt
D
D
Marwan
W
W
D001426:Bacterial Proteins; D001565:Benzoates / Q000494:pharmacology*; D019817:Benzoic Acid; D002633:Chemotaxis / Q000187:drug effects; D003593:Cytoplasm / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029968:Escherichia coli Proteins; D005649:Fumarate Hydratase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D005650:Fumarates / Q000378:metabolism*; D017353:Gene Deletion; D007211:Indoles / Q000494:pharmacology*; D008565:Membrane Proteins / Q000378:metabolism; D000072236:Methyl-Accepting Chemotaxis Proteins; D010084:Oxidation-Reduction; D010766:Phosphorylation; D015398:Signal Transduction
D001426:Bacterial Proteins; D001565:Benzoates; D004791:Enzyme Inhibitors; D029968:Escherichia coli Proteins; D005650:Fumarates; D007211:Indoles; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C000607606:cheY protein, E coli; C030374:indole; C032005:fumaric acid; D019817:Benzoic Acid; D005649:Fumarate Hydratase