Developmental regulation of nuclear glycosyl transfer in Cictyostelium discoideum

A differentiation-dependent polyisoprenol kinase in Dictyostelium discoideum

Crude membrane fractions of Dictyostelium discoideum show the capacity to synthesize (1--3H)dolicholphosphate from (1--3H)dolichol. Formation of dolicholphosphate increased continuously over the first 15 min. The reaction rate was nearly linear with respect to the dolichol content up to 150 microM. The phosphate donor for the reaction is CTP. The optimum concentration of CTP is about 0,75 mM. The reaction is dependent on divalent metal ions, magnesium being more effective than calcium or manganese. The activity of the polyisoprenol kinase depends on the course of the early development. Maximum enzyme activities are present 4--6 h after the induction of the differentiation.

Products of endogenous N-acetylglucosaminyltransferase activity of Dictyostelium discoideum during growth and early development

In the presence of Mn2+ and uridine diphosphate-N-acetyl-D-[14C]glucosamine, a total particulate fraction prepared from Dictyostelium discoideum amoebae catalyzed the transfer of N-acetyl[14C]glucosamine to endogenous membrane protein acceptors. No transfer to lipid acceptors was evident. The 14C products obtained from growth-phase and aggregation-competent amoebae were converted to glycopeptides by pronase digestion. The respective glycopeptides appeared identical in their chemical and chromatographic properties, suggesting that the same activity was functioning in both growing and differentiating cells. The results provided no evidence for developmental regulation of this activity in D. discoideum.

The biosynthesis of glycolipids during the differentiation of the slime mold Dictyostelium discoideum

In the slime mold Dictyostelium discoideum polysioprenylphosphomannosides are substrates for membrane bound mannosyltransferases; the isolated and purified isoprenyl derivatives transfer mannose to protein in vitro in presence of membrane fractions. The biosynthesis of the mannolipids as well as the biosynthesis of a glucose containing cerebroside, which becomes synthesized in an early stage of the cell development proceeds under control of the cell differentiation. The isolation procedure and the properties of the glycolipids are described, and their functions for the cellular development are discussed.