Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
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Query: EC:2.7.1.1 (
hexokinase
)
5,274
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Yeast strains bearing a deficiency in trehalose-6-phosphate synthase activity are unable to accumulate trehalose on any carbon source unless they contain one of the MAL genes. If the gene is inducible then synthesis of trehalose occurs specifically during growth on maltose: when the MAL gene is constitutive then trehalose accumulation can also be seen when cells are grown on glucose. Different systems for trehalose synthesis were suggested: one of them would require the UDPG-linked
trehalose synthase
whereas the second would utilize an alternative pathway. We proposed a mechanism by which the gene-product of a MAL gene would serve as a common positive regulator for the expression of the genes coding for maltose permease, alpha-glucosidase and some component of the trehalose accumulation system. In order to elucidate this novel pathway a strain lacking UDPG-linked
trehalose synthase
activity and harboring a defect in maltose uptake was constructed. Excessive maltose uptake resulted in accumulation of intracellular maltose, and twice as much trehalose as in a control strain. Partial inhibition of
hexokinase
by xylose affected the ratio between internal maltose and trehalose and significantly reduced glycogen synthesis. Sodium fluoride also blocked glycogen synthesis but allowed for trehalose accumulation. Moreover, a mutant which lacks hexokinase I and II was unable to accumulate trehalose when grown on glucose in spite of the presence of a constitutive MAL2 gene. These results suggest that trehalose synthesis would require G-6-P formation derived from maltose. Such a deviation would allow for slowing down the glycolytic flux which, in turn, would favour efficient maltose utilization.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Further evidence for the alternative pathway of trehalose synthesis linked to maltose utilization in Saccharomyces. 344 33
