The <i>Gup1</i> homologue of <i>Trypanosoma brucei</i> is a GPI glycosylphosphatidylinositol remodelase

Jaquenoud, Malika; Pagac, Martin; Signorell, Aita; Benghezal, Mohammed; Jelk, Jennifer; Bütikofer, Peter; Conzelmann, Andreas

doi:10.1111/j.1365-2958.2007.06043.x

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The Gup1 homologue of Trypanosoma brucei is a GPI glycosylphosphatidylinositol remodelase

Jaquenoud, Malika Department of Medicine/Biochemistry, University of Fribourg, Switzerland
Pagac, Martin Department of Medicine/Biochemistry, University of Fribourg, Switzerland
Signorell, Aita Institute of Biochemistry and Molecular Medicine, University of Bern, Switzerland
Benghezal, Mohammed Department of Medicine/Biochemistry, University of Fribourg, Switzerland - Helicobacter Research Laboratory, University of Western Australia, Nedlands, Western Australia
Jelk, Jennifer Institute of Biochemistry and Molecular Medicine, University of Bern, Switzerland
Bütikofer, Peter Institute of Biochemistry and Molecular Medicine, University of Bern, Switzerland
Conzelmann, Andreas Department of Medicine/Biochemistry, University of Fribourg, Switzerland

07.12.2007

Published in:

Molecular Microbiology. - 2008, vol. 67, no. 1, p. 202-212

English 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 gup1Δ yeast cells partially normalizes the gup1Δ 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.

Faculty

Faculté des sciences et de médecine

Department

Département de Biologie

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