The Gup1 homologue of Trypanosoma brucei is a GPI glycosylphosphatidylinositol remodelase.
Glycosylphosphatidylinositol (GPI) lipids of Trypanosoma brucei undergo lipid remodelling, whereby longer fatty acids on the glycerol are replaced by myristate (C14:0). A similar process occurs on GPI proteins of Saccharomyces cerevisiae where Per1p first deacylates, Gup1p subsequently reacylates the anchor lipid, thus replacing a shorter fatty acid by C26:0. Heterologous expression of the GUP1 homologue of T. brucei in gup1Delta yeast cells partially normalizes the gup1Delta phenotype and restores the transfer of labelled fatty acids from Coenzyme A to lyso-GPI proteins in a newly developed microsomal assay. In this assay, the Gup1p from T. brucei (tbGup1p) strongly prefers C14:0 and C12:0 over C16:0 and C18:0, whereas yeast Gup1p strongly prefers C16:0 and C18:0. This acyl specificity of tbGup1p closely matches the reported specificity of the reacylation of free lyso-GPI lipids in microsomes of T. brucei. Depletion of tbGup1p in trypanosomes by RNAi drastically reduces the rate of myristate incorporation into the sn-2 position of lyso-GPI lipids. Thus, tbGup1p is involved in the addition of myristate to sn-2 during GPI remodelling in T. brucei and can account for the fatty acid specificity of this process. tbGup1p can act on GPI proteins as well as on GPI lipids.
Department of Medicine/Biochemistry, University of Fribourg, Chemin du Musée 5, CH-1700, Switzerland.
Malika
M
Jaquenoud
Martin
M
Pagac
Aita
A
Signorell
Mohammed
M
Benghezal
Jennifer
J
Jelk
Peter
P
Bütikofer
Andreas
A
Conzelmann
D000217:Acyltransferases / Q000378:metabolism*; D000818:Animals; D005227:Fatty Acids / Q000378:metabolism; D017261:Glycosylphosphatidylinositols / Q000235:genetics / Q000378:metabolism*; D050356:Lipid Metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008861:Microsomes / Q000201:enzymology; D019814:Myristic Acid / Q000378:metabolism; D010641:Phenotype; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D014346:Trypanosoma brucei brucei / Q000201:enzymology* / Q000235:genetics; D015003:Yeasts / Q000201:enzymology / Q000235:genetics
D005227:Fatty Acids; D017261:Glycosylphosphatidylinositols; C414103:Gup1 protein, S cerevisiae; D026901:Membrane Transport Proteins; D015800:Protozoan Proteins; D029701:Saccharomyces cerevisiae Proteins; D019814:Myristic Acid; D000217:Acyltransferases