Hexose phosphorylation by the ruminal bacterium Selenomonas ruminantium.
Three strains of Selenomonas ruminantium (D, GA192, and H18) were surveyed for phosphorylation of D-glucose and 2-deoxyglucose by phosphoenolpyruvate and ATP. Cells of all three strains that had been treated with toluene had high rates of hexose phosphorylation with either phosphoryl donor; this activity was constitutive in strain D. Glucose phosphorylation that was dependent on phosphoenolpyruvate was maximal at pH 7.2, remained fairly high at pH 6.5, but decreased (> or = 65%) at pH 5.0 for all strains. Cell extracts were used to evaluate the involvement of soluble kinases in 2-deoxyglucose phosphorylation. Both glucose and 2-deoxyglucose were phosphorylated by ATP, but phosphorylation of either hexose was negligible with phosphoenolpyruvate in each bacterium. Because phosphoenolpyruvate could not serve as a phosphoryl donor, the activity dependent on phosphoenolpyruvate in cells treated with toluene might have been due to a phosphotransferase system associated with the membrane. Unlabeled 2-deoxyglucose was a strong inhibitor (> or = 59%) of [14C]glucose phosphorylation with ATP by cell extracts of all S. ruminantium strains, and unlabeled glucose was a strong inhibitor (> or = 78%) of [14C]2-deoxyglucose phosphorylation with ATP. Based on Lineweaver-Burk kinetics, 2-deoxyglucose was a competitive inhibitor of initial rates of kinase activity in strains D, GA192, and H18. These results collectively suggest that glucose phosphorylation with phosphoenolpyruvate and 2-deoxyglucose phosphorylation with ATP are common traits in these strains of S. ruminantium.
Martin
S A
SA
Department of Animal and Dairy Science, University of Georgia, Athens 30602-2771, USA.
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D003847:Deoxyglucose / Q000378:metabolism*; D005941:Glucokinase / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D006089:Gram-Negative Anaerobic Bacteria / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D010728:Phosphoenolpyruvate / Q000378:metabolism; D010766:Phosphorylation; D012417:Rumen / Q000382:microbiology*
D010728:Phosphoenolpyruvate; D000255:Adenosine Triphosphate; D003847:Deoxyglucose; D005941:Glucokinase; D005947:Glucose