Fatty acid remodeling: a novel reaction sequence in the biosynthesis of trypanosome glycosyl phosphatidylinositol membrane anchors.
The trypanosome variant surface glycoprotein (VSG) is anchored to the plasma membrane via a glycosyl phosphatidylinositol (GPI). The GPI is synthesized as a precursor, glycolipid A, that is subsequently linked to the VSG polypeptide. The VSG anchor is unusual, compared with anchors in other cell types, in that its fatty acid moieties are exclusively myristic acid. To investigate the mechanism for myristate specificity we used a cell-free system for GPI biosynthesis. One product of this system, glycolipid A', is indistinguishable from glycolipid A except that its fatty acids are more hydrophobic than myristate. Glycolipid A' is converted to glycolipid A through highly specific fatty acid remodeling reactions involving deacylation and subsequent reacylation with myristate. Therefore, myristoylation occurs in the final phase of trypanosome GPI biosynthesis.
Department of Biological Chemistry, Johns Hopkins School of Medicine, Baltimore, Maryland 21205.
W J
WJ
Masterson
J
J
Raper
T L
TL
Doering
G W
GW
Hart
P T
PT
Englund
D000818:Animals; D002474:Cell-Free System; D002855:Chromatography, Thin Layer; D006017:Glycolipids / Q000096:biosynthesis* / Q000302:isolation & purification; D017261:Glycosylphosphatidylinositols; D006155:Guanosine Diphosphate Mannose / Q000378:metabolism; D008358:Mannose / Q000378:metabolism; D019814:Myristic Acid; D009227:Myristic Acids / Q000378:metabolism; D010716:Phosphatidylinositols / Q000096:biosynthesis*; D014346:Trypanosoma brucei brucei / Q000378:metabolism*; D014643:Variant Surface Glycoproteins, Trypanosoma / Q000096:biosynthesis*
D006017:Glycolipids; D017261:Glycosylphosphatidylinositols; D009227:Myristic Acids; D010716:Phosphatidylinositols; D014643:Variant Surface Glycoproteins, Trypanosoma; D019814:Myristic Acid; D006155:Guanosine Diphosphate Mannose; D008358:Mannose