Kinetics of D-glucose and 2-deoxy-D-glucose transport by Rhodotorula glutinis.
The yeast Rhodotorula glutinis (Rhodosporidium toruloides) is capable of accumulative transport of a wide variety of monosaccharides. Initial velocity studies of the uptake of 2-deoxy-D-glucose were consistent with the presence of at least two carriers for this sugar in the Rhodotorula plasma membrane. Non-linear regression analysis of the data returned maximum velocities of 0.8 +/- 0.2 and 2.0 +/- 0.2 nmol/min per mg (wet weight) and Km values of 18 +/- 4 and 120 +/- 20 microM, respectively, for the two carriers. Kinetic studies of D-glucose transport also revealed two carriers with maximum velocities of 1.1 +/- 0.4 and 2.4 +/- 0.4 nmol/min per mg (wet weight) and Km values of 12 +/- 3 and 55 +/- 12 microM. As expected, 2-deoxy-D-glucose was a competitive inhibitor of D-glucose transport. Ki values for the inhibition were 16 +/- 8 and 110 +/- 40 microM. These Ki values were in good agreement with the Km values for 2-deoxy-D-glucose transport. D-Xylose, the 5-deoxymethyl analog of D-glucose, appears to utilize the D-glucose/2-deoxy-D-glucose carriers. This pentose was observed to be a competitive inhibitor of D-glucose (Ki values = 0.14 +/- 0.06 and 5.6 +/- 1.6 mM) and 2-deoxy-D-glucose (Ki values = 0.15 +/- 0.07 and 4.6 +/- 1.2 mM) transport.
D001667:Binding, Competitive; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003837:Deoxy Sugars / Q000378:metabolism*; D003847:Deoxyglucose / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D007700:Kinetics; D003904:Mitosporic Fungi / Q000378:metabolism*; D012248:Rhodotorula / Q000378:metabolism*; D014994:Xylose / Q000378:metabolism
D002352:Carrier Proteins; D003837:Deoxy Sugars; D003847:Deoxyglucose; D014994:Xylose; D005947:Glucose