The dihydroxyacetonephosphate pathway for biosynthesis of ether lipids in Leishmania mexicana promastigotes.
Biosynthetic studies using both [14C]- and [32P]-labelled substrates and a cell-free system to synthesise 1-O-alkyl moieties in glycerolipids, have shown that the three initial steps in ether-lipid biosynthesis in Leishmania mexicana promastigotes resemble those described for mammals and are associated with glycosomes. Purified glycosomes were able to sequentially synthesise the first intermediates of the ether-lipid biosynthetic pathway [acyl-dihydroxyacetonephosphate (DHAP), alkyl-DHAP and acyl/alkyl-glycerol-3-phosphate (G3P)] when incubated in the presence of radiolabelled DHAP, palmitoyl-CoA, hexadecanol and NADPH. However, when glycosomes were incubated under the same conditions in the presence of radiolabelled G3P, a rapid synthesis of acyl-G3P and phosphatidic acid was observed without any formation of alkyl-G3P, suggesting that the enzyme alkyl-synthase recognises only acyl-DHAP as substrate. Both the DHAP acyltransferase (DHAP-AT) and alkyl-DHAP synthase activities were located inside glycosomes whereas the alkyl/acyl-DHAP oxidoreductase activity was associated with the cytoplasmic face of the glycosomal membrane. The G3P acyltransferase (G3P-AT) and lyso-phosphatidic acid acyltransferase activities were not found inside glycosomes. The results suggest that the DHAP-AT and G3P-AT activities are catalysed by two distinct enzymes associated with different sub-cellular compartments.
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Research Unit for Tropical Diseases, Catholic University of Louvain, Brussels, Belgium.
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D019883:Alkyl and Aryl Transferases; D000818:Animals; D003066:Coenzyme A Ligases / Q000378:metabolism; D004099:Dihydroxyacetone Phosphate / Q000096:biosynthesis* / Q000737:chemistry; D004789:Enzyme Activation; D005994:Glycerophosphates / Q000378:metabolism; D007894:Leishmania mexicana / Q000201:enzymology / Q000378:metabolism*; D015388:Organelles / Q000201:enzymology / Q000378:metabolism; D010171:Palmitoyl Coenzyme A / Q000378:metabolism; D010742:Phospholipid Ethers / Q000737:chemistry / Q000378:metabolism*; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D013347:Subcellular Fractions / Q000201:enzymology; D013401:Sugar Alcohol Dehydrogenases / Q000378:metabolism; D014166:Transferases / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000201:enzymology; D000098859:Long-Chain-Fatty-Acid-CoA Ligase
D005994:Glycerophosphates; D010742:Phospholipid Ethers; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D010171:Palmitoyl Coenzyme A; D004099:Dihydroxyacetone Phosphate; D013401:Sugar Alcohol Dehydrogenases; C022312:acylglycerone-phosphate reductase; D014166:Transferases; D019883:Alkyl and Aryl Transferases; C019654:alkylglycerone-phosphate synthase; D003066:Coenzyme A Ligases; C090799:FAA2 protein, S cerevisiae; D000098859:Long-Chain-Fatty-Acid-CoA Ligase