Characterisation of glucose transport in the hyperthermophilic Archaeon Sulfolobus solfataricus

Sulfolobus solfataricus is a hyperthermophilic Archaean growing at 80 degrees C, pH 3. The glucose transport system of this organism has been characterised kinetically at this temperature and pH using 2-deoxy-D-glucose: the sugar analogue is transported into the cells with a K-m = 1.8 +/- 0.3 mu M and a V-max = 3.6 +/- 0.1 mmol min(-1) (mg protein)(-1), with an intracellular accumulation of up to 200-fold over the extracellular concentration. Transport was significantly reduced at pH 5. Inhibition of 2-deoxy-D-glucose transport was investigated using a variety of sugars rind sugar analogues; D-glucose, D-galactose and D-mannose showed the highest affinity for the transporter, with D-glucose possessing a K-i = 120 +/- 20 nM.