PubMed · 5237347
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J M Wood. 1967. A dextransucrase activity from Streptococcus FA-1.. https://doi.org/10.1016/0003-9969(67)90202-6
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The addition of glucose to cells of the yeast Saccharomyces cerevisiae triggers a variety of regulatory phenomena. Initial glucose metabolism is required for the induction of most of them. Mutants deficient in both glucose-induced signalling and the control of initial glucose metabolism have a defect in the trehalose-6-phosphate synthase catalytic subunit of the trehalose synthase complex. This finding has raised novel questions about the control of glucose influx into glycolysis in yeast and its connection to the glucose-sensing mechanism. This dual function of the trehalose-6-phosphate synthase subunit has been found in several yeast species, suggesting that this control system might be widespread in fungi and possibly also in other organisms.
When different strains of Saccharomyces cerevisiae grown at 23 degrees C were transferred to 36 degrees C, trehalose and glycogen were accumulated. Glycogen accumulation was less extensive and its synthesis started at least 15 min after initiation of trehalose synthesis. The steady-state intracellular concentration of trehalose increased simultaneously with the activities of the enzymes trehalose-6P synthase, UDPG-pyrophosphorylase, phosphoglucomutase and trehalase. A small but significant change was observed in hexokinase activity. Our results directly implicate isoform PII of hexokinase and the minor isoform of phosphoglucomutase in the pathway of trehalose formation during heat-shock. We also showed that the major isoform of phosphoglucomutase increased in activity but was not essential for trehalose accumulation. Studies with the glucose uptake system indicated that trehalose accumulation could be primarily determined by intracellular availability of substrates due to the increase in the rate of glucose uptake. The increased uptake appears to have two components: a kinetic effect of temperature upon glucose transporters and an increase in the numbers of molecules of the transporters, probably mediated by synthesis de novo.
This review covers some of the more recent developments in the understanding of the different glucosyltransferases (GTFs) secreted by oral streptococci, particularly those produced by Streptococcus salivarius--a species that has been intensively studied at the Institute of Dental Research in Sydney.