Elimination of GPI2 suppresses glycosylphosphatidylinositol GlcNAc transferase activity and alters GPI glycan modification in Trypanosoma brucei.

Jenni, Aurelio; Knüsel, Sebastian; Nagar, Rupa; Benninger, Mattias; Häner, Robert; Ferguson, Michael A J; Roditi, Isabel; Menon, Anant K; Bütikofer, Peter (2021). Elimination of GPI2 suppresses glycosylphosphatidylinositol GlcNAc transferase activity and alters GPI glycan modification in Trypanosoma brucei. The journal of biological chemistry, 297(2), p. 100977. American Society for Biochemistry and Molecular Biology 10.1016/j.jbc.2021.100977

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Many eukaryotic cell-surface proteins are post-translationally modified by a glycosylphosphatidylinositol (GPI) moiety that anchors them to the cell membrane. The biosynthesis of GPI anchors is initiated in the endoplasmic reticulum by transfer of GlcNAc from UDP-GlcNAc to phosphatidylinositol. This reaction is catalyzed by GPI GlcNAc transferase, a multisubunit complex comprising the catalytic subunit Gpi3/PIG-A as well as at least five other subunits, including the hydrophobic protein Gpi2, which is essential for the activity of the complex in yeast and mammals, but the function of which is not known. To investigate the role of Gpi2, we exploited Trypanosoma brucei (Tb), an early diverging eukaryote and important model organism that initially provided the first insights into GPI structure and biosynthesis. We generated insect-stage (procyclic) trypanosomes that lack TbGPI2 and found that in TbGPI2-null parasites, (i) GPI GlcNAc transferase activity is reduced, but not lost, in contrast with yeast and human cells, (ii) the GPI GlcNAc transferase complex persists, but its architecture is affected, with loss of at least the TbGPI1 subunit, and (iii) the GPI anchors of procyclins, the major surface proteins, are underglycosylated when compared with their WT counterparts, indicating the importance of TbGPI2 for reactions that occur in the Golgi apparatus. Immunofluorescence microscopy localized TbGPI2 not only to the endoplasmic reticulum but also to the Golgi apparatus, suggesting that in addition to its expected function as a subunit of the GPI GlcNAc transferase complex, TbGPI2 may have an enigmatic noncanonical role in Golgi-localized GPI anchor modification in trypanosomes.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Biochemistry and Molecular Medicine
08 Faculty of Science > Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP)
08 Faculty of Science > Department of Biology > Institute of Cell Biology

Graduate School:

Graduate School for Cellular and Biomedical Sciences (GCB)

UniBE Contributor:

Jenni, Aurelio; Knüsel, Sebastian; Benninger, Mattias; Häner, Robert; Roditi, Isabel and Bütikofer, Peter

Subjects:

500 Science > 570 Life sciences; biology
600 Technology > 610 Medicine & health
500 Science > 540 Chemistry

ISSN:

1083-351X

Publisher:

American Society for Biochemistry and Molecular Biology

Language:

English

Submitter:

Barbara Järmann-Bangerter

Date Deposited:

09 Sep 2021 10:00

Last Modified:

09 Sep 2021 10:00

Publisher DOI:

10.1016/j.jbc.2021.100977

PubMed ID:

34284059

Uncontrolled Keywords:

Golgi Trypanosoma brucei endoplasmic reticulum (ER) glycosylphosphatidylinositol (GPI anchor) glycosyltransferase phosphatidylinositol procyclin social motility

BORIS DOI:

10.48350/158326

URI:

https://boris.unibe.ch/id/eprint/158326

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