Transport ofd-Arabinose-5-Phosphate andd-Sedoheptulose-7-Phosphate by the Hexose Phosphate Transport System ofSalmonella typhimurium

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Abstract
D-Arabinose-5-phosphate andd-sedoheptulose-7-phosphate were found to be substrates, although not inducers, of the hexose phosphate transport system ofSalmonella typhimurium. Transport of these two sugar phosphates by wild-type strains required preinduction of the hexose phosphate transport system. A mutant ofS. typhimuriumconstitutive for this system also transportedd-arabinose-5-phosphate andd-sedoheptulose-7-phosphate in a constitutive fashion. Glucose-6-phosphate was a potent competitor of the transport of bothd-arabinose-5-phosphate andd-sedoheptulose-7-phosphate. TheKmvalues for transport ofd-glucose-6-phosphate,d-arabinose-5-phosphate, andd-sedoheptulose-7-phosphate were 0.13, 0.32 and 1.61 mM, respectively. The apparentVmaxvalues for transport ofd-glucose-6-phosphate,d-arabinose-5-phosphate, andd-sedoheptulose-7-phosphate were 6.3, 13.2 and 3.0 nmol per min per 5 × 108bacteria, respectively.d-Ribulose-5-phosphate andd-xylulose-5-phosphate did not inhibit transport of the above substrates, whereasd-ribose-5-phosphate was a weak inhibitor ofd-sedoheptulose-7-phosphate transport.