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The deficiency of sterol biosynthesis in Saccharomyces cerevisiae affects the synthesis of glycosyl derivatives of dolichyl phosphates
Authors:Anna Szkopi&#;ska  Joanna Rytka  Francis Karst  Gra&#;yna Palamarczyk
Institution:Institute of Biochemistry and Biophysics PAN, Warsaw, Poland; Institut de Biologie Moléculaire et d'Ingénierie Génétique, Poitiers, France
Abstract:Abstract Mutants deficient in sterol (thermosensitive ergosterol auxotrophs) erg 8, 9, 12 and heme synthesis hem 1, 12 were screened for the level of free dolichol and dolichyl phosphate synthesized in the mevalonate pathway as well as for the activity of dolichyl phosphate-dependent glycosyl transferases. The amount of DolP synthesized via CTP-dependent phosphorylation was the same in mutants and parental strains. However, mannosylation and glucosylation of endogenous dolichyl phosphates in ergosterol mutants was about four times lower compared to parental strains, while the same reactions carried out with exogenous Dol24P reached 80% of the level observed in parental strains indicating that activities of DolPMan and DolPGlc synthases are not the rate-limiting factors. It is postulated that the de novo synthesis of DolP is impaired in the ergosterol mutants. Moreover, a block in the ergosterol branch of the metabolic pathway ( erg 9 ) causes an increase in the de novo synthesis of dolichyl phosphate.
Keywords:Dolichyl phosphate  Ergosterol mutants              Saccharomyces cerevisiae
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