Characterization of a glucose transport system in Vibrio parahaemolyticus.
Cells of a glucose-PTS (phosphoenolpyruvate:carbohydrate phosphotransferase system)-negative mutant of Vibrio parahaemolyticus transport D-glucose in the presence of Na+. Maximum stimulation of D-glucose transport was observed at 40 mM NaCl, and Na+ could be replaced partially with Li+. Addition of D-glucose to the cell suspension under anaerobic conditions elicited Na+ uptake. Thus, we conclude that glucose is transported by a Na+/glucose symport mechanism. Calculated Vmax and Km values for the Na(+)-dependent D-glucose transport were 15 nmol/min/mg of protein and 0.57 mM, respectively, when NaCl was added at 40 mM. Na+ lowered the Km value without affecting the Vmax value. D-Glucose was the best substrate for this transport system, followed by galactose, alpha-D-fucose, and methyl-alpha-glucoside, judging from the inhibition pattern of the glucose transport. D-Glucose itself partly repressed the transport system when cells were grown in its presence.
Department of Microbiology, Faculty of Pharmaceutical Sciences, Okayama University, Japan.
R I
RI
Sarker
W
W
Ogawa
M
M
Tsuda
S
S
Tanaka
T
T
Tsuchiya
D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D005960:Glucosides / Q000378:metabolism; D008094:Lithium / Q000378:metabolism; D009005:Monosaccharides / Q000378:metabolism; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D014736:Vibrio parahaemolyticus / Q000378:metabolism*
D002352:Carrier Proteins; D005960:Glucosides; D009005:Monosaccharides; D008094:Lithium; D012964:Sodium; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D005947:Glucose; D011188:Potassium