Uncoupler-resistant glucose uptake by the thermophilic glycolytic anaerobe Thermoanaerobacter thermosulfuricus (Clostridium thermohydrosulfuricum)

• Published in: Applied and Environmental Microbiology Vol. 59; no. 9; pp. 2984 - 2990
• Main Authors: Cook, G.M, Janssen, P.H, Morgan, H.W
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.09.1993
• Subjects: active transport; anaerobes; Bacteria; bacterial proteins; Biochemistry; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; cell membranes; diffusion; enzyme activity; facilitated diffusion; Fundamental and applied biological sciences. Psychology; glucokinase; glucose; Mission oriented research; phosphorylation; Physiology and Biotechnology; Physiology and metabolism; premeases; thermophilic bacteria; uptake; Enzyme; Transferases; Thermophily; Glucose; Metabolism; Uptake; Mechanism; Enzymatic activity; Anaerobe; Membrane transport; Glucokinase; Bacteria; Kinetics
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.59.9.2984-2990.1993

The transport of glucose across the bacterial cell membrane of Thermoanaerobacter thermosulfuricus Clostridium thermohydrosulfuricum) Rt8.B1 was governed by a permease which did not catalyze concomitant substrate transport and phosphorylation and thus was not a phosphoenolpyruvate-dependent phosphotransferase. Glucose uptake was carrier mediated, could not be driven by an artificial membrane potential (delta psi) in the presence or absence of sodium, and was not sensitive to inhibitors which dissipate the proton motive force (delta p; tetrachlorosalicylanilide, N,N-dicyclohexylcarbodiimide, and 2,4-dinitrophenol), and no uptake of the nonmetabolizable analog 2-deoxyglucose could be demonstrated. The glucokinase apparent Km for glucose (0.21 mM) was similar to the Kt (affinity constant) for glucose uptake (0.15 mM), suggesting that glucokinase controls the rate of glucose uptake. Inhibitors of ATP synthesis (iodoacetate and sodium fluoride) also inhibited glucose uptake, and this effect was due to a reduction in the level of ATP available to glucokinase for glucose phosphorylation. These results indicated that T. thermosulfuricus Rt8.B1 lacks a concentrative uptake system for glucose and that uptake is via facilitated diffusion, followed by ATP-dependent phosphorylation by glucokinase. In T. thermosulfuricus Rt8.B1, glucose is metabolized by the Embden-Meyerhof-Parnas pathway, which yields 2 mol of ATP (G. M. Cook, unpublished data). Since only 1 mol of ATP is used to transport 1 mol of glucose, the energetics of this system are therefore similar to those found in bacteria which possess a phosphotransferase.