Continuing studies with the amino acid stimulated sugar transport system of Fusobacterium nucleatum have included a determination of transport specificity, as well as new information about the mechanism of transport and patterns of use of the glucose storage product. Competition studies with a wide variety of sugars and sugar analogs demonstrated that glucose and galactose are mutual and exclusive competitors. The transport system requires the alpha-D-glucopyranose molecule but allows a single hydroxyl group at the number 4 position to be in either possible orientation (glucose or galactose). Results of competition studies using analogs of galactose where identical to the results obtained with glucose analogs: glucose being the exclusive competitor for galactose transport. The glutamate stimulated transport system proved highly sensitive to proton- conducting uncouplers suggesting proton motive force transport. Evidence was obtained for cell extracts independent glucose and galactose kinases which depend on ATP or acetyl phosphate. The use of the preformed sugar storage product of F. nucleatum is spared when energy is available from the fermentation of amino acids. Glutamate, lysine, and histidine blocked the loss of C-14 from a washed cell suspension which had performed glucose storage product. Aerobic conditions suppressed the use of amino acids in washed cells suspensions and resulted in a release of the glucose and galactose storage products in the presence of glutamate. Analysis of the fermentation product from the use of glucose storage product revealed major differences in the ratios of acetic and lactic acids formed depending on the presence of glutamate. Low molecular weight intermediates resulting from the use of the glucose storage product have been fractionated by gel filtration and are being characterized.
NIH ExPorter
NIH ExPorter