The involvement of hexokinases in trehalose synthesis.
Yeast cells harboring a MAL2-8c gene accumulate trehalose during the transition phase of growth on glucose due to the presence of the ADPG-dependent trehalose 6-phosphate synthase. Under these conditions, glucokinase appeared not to provide G-6-P for trehalose synthesis and the two hexokinases seemed to act synergistically. After incubation in d-xylose, trehalose levels in these cells dropped almost in 90%, confirming the involvement of both hexokinases in the accumulation of this carbohydrate. Nevertheless, G-6-P levels appeared to be similar in all strains. Some explanations for this paradox are discussed. In stationary phase, neither of the three isoenzymes were involved in trehalose synthesis. Possibly, gluconeogenesis provides the substrate for trehalose synthesis at that stage.
Peixoto
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DN
Departamento de Bioquímica, Universidade Federal do Rio de Janeiro, Brasil.
Panek
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AD
D005838:Genotype; D019298:Glucose-6-Phosphate / Q000378:metabolism; D006593:Hexokinase / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D014199:Trehalose / Q000096:biosynthesis*
D019298:Glucose-6-Phosphate; D014199:Trehalose; D006593:Hexokinase