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Candida albicans phosphatidylinositol synthase has common features with both Saccharomyces cerevisiae and mammalian phosphatidylinositol synthases
Author(s) -
Antonsson Bruno E.,
Klig Lisa S.
Publication year - 1996
Publication title -
yeast
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.923
H-Index - 102
eISSN - 1097-0061
pISSN - 0749-503X
DOI - 10.1002/(sici)1097-0061(199604)12:5<449::aid-yea927>3.0.co;2-p
Subject(s) - biochemistry , phosphatidylinositol , biology , enzyme , atp synthase , diacylglycerol kinase , inositol , saccharomyces cerevisiae , candida albicans , microsome , pi , yeast , kinase , protein kinase c , genetics , receptor
Phosphatidylinositol (PI) synthase (cytidine 5′‐diphospho (CDP)‐1,2‐diacyl‐ sn ‐glycerol: myo ‐inositol 3phosphatidyltransferase, EC 2.7.8.11) was isolated from the microsomal cell fraction of Candida albicans . The Triton X‐100 extracted enzyme was enriched 140‐fold by affinity chromatography on CDP‐diacylglycerol–Sepharose. The enzyme had a pH optimum at 9·5 in glycine/NaOH buffer. It had an absolute requirement for Mg 2+ or Mn 2+ and was inhibited by Ca 2+ and Zn 2+ . Maximal activity was at 0·2–0·6 mm‐CDP‐diacylglycerol, higher concentrations inhibited the enzyme. With 2′‐deoxy‐CDP‐diacylglycerol as the lipid substrate, optimal activity was at 0·7 mm. The K m for myo‐inositol was determined to be 0·55 mm. The optimal temperature for the PI synthase reaction was 55°C. The C. albicans PI synthase shows differences to the Saccharomyces cerevisiae enzyme, such as activation by bivalent cations, inhibition by nucleotides, temperature optimum and activation energy, but also to the human PI synthase in preference for the lipid substrates, inhibition by nucleoside monophosphates and stabilization by Mn 2+ and phospholipids.