FATTY-ACID UPTAKE IN ESCHERICHIA-COLI - REGULATION BY RECRUITMENT OF FATTY ACYL-COA SYNTHETASE TO THE PLASMA-MEMBRANE

Fatty acid uptake in Escherichia coli has been shown to be inhibited by starvation and to be reversed by a short preincubation of the starved cells with D- or L-lactate, succinate, and acetate; these effects on oleate uptake were due to regulation of the rate-limiting step which involves fatty acyl-CoA synthetase. Investigation into the mechanism of regulation of fatty acyl-CoA synthetase showed that D-lactate did not affect the activity of the enzyme directly. Fatty acyl-CoA synthetase was found to be activated by about 20-fold by Triton X-100 and by another 4-fold by the addition of bacterial membranes. D-Lactate treatment was shown to result in coisolation of fatty acyl-CoA synthetase with the plasma membrane; these results are consistent with the interpretation that recruitment of the enzyme to the plasma membrane by D-lactate results in its activation and consequently in the increased level of fatty acid uptake.