Regulation of phosphatidylcholine biosynthesis in Plasmodium-infected erythrocytes.

摘要: Abstract Plasmodium knowlesi-infected erythrocytes efficiently incorporated choline and metabolize it into phosphatidylcholine via the de novo Kennedy pathway. Nor formation of either betaine or acetylcholine was detected. At physiological concentrations external choline, isotopic equilibrium between intracellular phosphocholine reached in less than 1 h, whereas labeled accumulated constantly, until at least 210 min. During this time, CDP-choline remained quite low compared to phosphocholine, which suggests that choline-phosphate cytidylyltransferase (EC 2.7.7.15) is rate-limiting step However, activity probably not saturated situ by since concentration, up 100 μM, can regulate biosynthesis level phosphocholine. This corroborated respective velocities affinity characteristics three enzymatic steps involved These results, together with localization both metabolites enzyme activities, provide a precise scheme dynamics biosynthesis. Concerning alternative pathway for methylation phosphatidylehanolamine, we show an increase could instigate concomitant decrease phosphatidylethanolamine methylation, indicating parasite able modulate its phosphatodylcholine biosyntheses.