Chemotactic-like response of Escherichia coli cells lacking the known chemotaxis machinery but containing overexpressed CheY.
We describe a chemotactic-like response of Escherichia coli strains lacking most of the known chemotaxis machinery but containing high levels of the response regulator CheY. The bacteria accumulated in aspartate-containing capillaries, they formed rings on tryptone-containing semisolid agar, and the probability of counterclockwise flagellar rotation transiently increased in response to stimulation with aspartate (10(-10)-10(-5) M; the response was inverted at > 10(-4) M). The temporal response was partial and delayed, as was the response of a control wild-type strain having a high CheY level. alpha-Methyl-DL-aspartate, a non-metabolizable analogue of aspartate as well as other known attractants of E. Coli, glucose and, to a lesser extent, galactose, maltose and serine caused a similar response. So did low concentrations of acetate and benzoate (which, at higher concentrations, act as repellents for wild-type E. coli). Other tested repellents such as indole, Ni2+ and CO2+ increased the clockwise bias. These observations raise the possibility that, at least when the conventional signal transduction components are missing, a non-conventional chemotactic signal transduction pathway might be functional in E. coli. Potential molecular mechanisms are discussed.
Barak
R
R
Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.
Eisenbach
M
M
D001089:Arabinose / Q000494:pharmacology; D001224:Aspartic Acid / Q000494:pharmacology; D001426:Bacterial Proteins; D002633:Chemotaxis / Q000502:physiology*; D003470:Culture Media; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D029968:Escherichia coli Proteins; D008565:Membrane Proteins / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D015398:Signal Transduction; D014364:Tryptophan / Q000494:pharmacology
D001426:Bacterial Proteins; D003470:Culture Media; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C000607606:cheY protein, E coli; D001224:Aspartic Acid; D014364:Tryptophan; D001089:Arabinose