Incorporation of label from acetate and laurate into the mannan of Leishmania donovani via the glyoxylate cycle.
Leishmania donovani promastigotes in late-stationary phase incorporated label from [2-14C]acetate and [1-14C]laurate into the mannose residues of mannan, thus confirming the presence of a functional glyoxylate bypass in these parasitic protozoa. Isolated, washed calls also incorporated label from [2-14C]acetate and [1-14C]laurate into mannan during a 1-hr incubation in buffer. Glucose had no effect on label incorporation into mannan, but glutamate caused over a four-fold increase in incorporation from [2-14C]acetate and a 2.4-fold increase from [1-14C]laurate. Staurosporine, a protein kinase inhibitor that inhibits glutamate and alanine oxidation, did not inhibit label incorporation from [2-14C]acetate into mannan. Hyperosmolality caused about a 33% inhibition of label incorporation into mannan. These results show the glyoxylate cycle and/or the subsequent biosynthetic pathway from fructose-6-phosphate to mannan are subject to regulation.
Keegan
F P
FP
Department of Biology, Guilford College, Greensboro, North Carolina 27410.
Blum
J J
JJ
D000085:Acetates / Q000378:metabolism*; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D002250:Carbon Radioisotopes; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D006038:Glyoxylates / Q000378:metabolism*; D007850:Lauric Acids / Q000378:metabolism*; D007893:Leishmania donovani / Q000254:growth & development / Q000378:metabolism*; D008351:Mannans / Q000096:biosynthesis*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011865:Radioisotope Dilution Technique; D019311:Staurosporine
D000085:Acetates; D000470:Alkaloids; D002250:Carbon Radioisotopes; D005971:Glutamates; D006038:Glyoxylates; D007850:Lauric Acids; D008351:Mannans; C030358:lauric acid; D018698:Glutamic Acid; D011493:Protein Kinase C; D019311:Staurosporine