Transport of lactate and acetate through the energized cytoplasmic membrane of Escherichia coli

Journal Article · Wed Jul 05 04:00:00 EDT 1995 · Biotechnology and Bioengineering

DOI:https://doi.org/10.1002/bit.260470103· OSTI ID:78134

Axe, D D; Bailey, J E ^[1]

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1. California Inst. of Technology, Pasadena, CA (United States). Div. of Chemistry and Chemical Engineering

Escherichia coli produces lactate and acetate in significant amounts during both aerobic and anaerobic glycolysis. A model describing the mechanism of protein-mediated lactate transport has previously been proposed. A simple theoretical analysis here indicates that the proposed model would drain cellular energy resources by catalytically dissipating the proton-motive force. An experimental analysis of lactate and acetate transport employs nuclear magnetic resonance (NMR) spectroscopy to measure the relative concentrations of these end products on the two sides of the cytoplasmic membrane of anaerobically glycolyzing cells. Comparison of measured concentration ratios of those expected at equilibrium for various transport modes indicates that acetate is a classical uncoupling agent, permeating the membrane at comparable rates in the dissociated and undissociated forms. The lactate concentration ratio changes markedly after an initial period of sustained glycolysis. This change is most readily explained as resulting from a lactate transport system that responds to an indicator of glycolytic activity. The data further indicate that lactate permeates the membrane in both dissociated and undissociated forms. Both acids, then, are capable of catalytically dissipating the proton-motive force.

• Sponsoring Organization: USDOE
• OSTI ID: 78134
• Journal Information: Biotechnology and Bioengineering, Journal Name: Biotechnology and Bioengineering Journal Issue: 1 Vol. 47; ISSN BIBIAU; ISSN 0006-3592
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
ACETATES
BIOTECHNOLOGY
CELL MEMBRANES
ESCHERICHIA COLI
GROWTH
LACTATES
MEMBRANE TRANSPORT
NMR SPECTRA
PERMEABILITY