title: Mechanism of regulation of glucose transport in Rhizobium leguminosarum.
abstract: Multiple glucose transport systems were distinguished in Rhizobium leguminosarum. We found nonlinear Lineweaver-Burk plots for the uptake of glucose, 2-deoxy-D-glucose, and alpha-methyl-D-glucoside, and this implied the existence of at least two uptake mechanisms. Different patterns of inhibition of 2-deoxy-D-glucose uptake and alpha-methyl-D-glucoside uptake at 0.1 mM by various carbohydrates revealed differences in the stereospecificities of the transport systems. Osmotic shock treatment abolished transport activities, and two independent glucose-binding activities were detected in the supernatants. Induction of glucose transport was repressed strongly by L-malate, even in the presence of excess D-glucose. Rhizobium bacteroids showed no significant glucose uptake activity at different oxygen concentrations. These results suggested that glucose transport is repressed by dicarboxylic acids during R. leguminosarum symbiosis.
mesh_terms: D001693:Biological Transport, Active / Q000187:drug effects; D002241:Carbohydrates / Q000494:pharmacology; D003847:Deoxyglucose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D007700:Kinetics; D008293:Malates / Q000494:pharmacology; D008757:Methylglucosides / Q000378:metabolism; D009997:Osmotic Pressure; D010100:Oxygen / Q000494:pharmacology; D012231:Rhizobium / Q000378:metabolism*
chemical_list: D002241:Carbohydrates; D008293:Malates; D008757:Methylglucosides; C027020:methylglucoside; C030298:malic acid; D003847:Deoxyglucose; D005947:Glucose; D010100:Oxygen