The Importance of the Binding-Protein-Dependent Mgl System to the Transport of Glucose in Escherichia Coli Growing on Low Sugar Concentrations

Res Microbiol. 1993 Sep;144(7):529-37. doi: 10.1016/0923-2508(93)90002-j.

Abstract

Glucose limitation in chemostats derepressed the binding-protein-dependent Mgl transport system, which is strongly repressed during growth in batch culture with high glucose levels. The limitation-induced Mgl activity was higher than that of batch cultures "fully induced" for the Mgl system after growth on glycerol plus fucose. Mgl- strains were impaired compared to Mgl+ bacteria in removing glucose from sugar-limited chemostats and were outcompeted in mixed continuous culture on limiting glucose. The influence of Mgl was not observed on growth with limiting maltose or non-carbohydrates, and thus was specific for glucose, a known substrate of the Mgl system. In the absence of the two glucose-specific membrane components of the phosphoenolpyruvate:sugar phosphotransferase system, non-PTS-dependent growth on glucose was observed in continuous culture, but only under sugar-limited conditions derepressing the Mgl system and not in glucose-rich batches or continuous culture. Hence growth of Escherichia coli on glucose at micromolar concentrations involves a significant contribution of a binding-protein-dependent transport system. The participation of multiple transporters in glucose transport can account for the complex non-hyperbolic dependence of growth-rate on glucose concentration and for discrepancies in studies attempting to describe growth on glucose purely in terms of phosphotransferase kinetics.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport, Active / physiology
  • Culture Media
  • Escherichia coli / growth & development*
  • Escherichia coli / metabolism
  • Galactose / pharmacokinetics
  • Glucose / pharmacokinetics*
  • In Vitro Techniques
  • Maltose / pharmacokinetics
  • Methylgalactosides / pharmacokinetics*
  • Monosaccharide Transport Proteins / metabolism
  • Phosphoenolpyruvate Sugar Phosphotransferase System / metabolism

Substances

  • Culture Media
  • Methylgalactosides
  • Monosaccharide Transport Proteins
  • Maltose
  • Phosphoenolpyruvate Sugar Phosphotransferase System
  • Glucose
  • Galactose