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Dual acylation accounts for the localization of {alpha}19-giardin in the ventral flagellum pair of Giardia lamblia


Saric, M; Vahrmann, A; Niebur, D; Kluempers, V; Hehl, A B; Scholze, H (2009). Dual acylation accounts for the localization of {alpha}19-giardin in the ventral flagellum pair of Giardia lamblia. Eukaryotic Cell, 8(10):1567-1574.

Abstract

A Giardia-specific protein family denominated as alpha-giardins, represents the major protein component, besides tubulin, of the cytoskeleton of the human pathogenic parasite Giardia lamblia. One of its members, alpha19-giardin, carries an N-terminal sequence extension of MGCXXS, which in many proteins serves as a target for dual lipid conjugation: myristoylation at the glycine residue after removal of the methionine and palmitoylation at the cysteine residue. As the first experimental evidence of a lipid modification, we found alpha19-giardin to be associated with the membrane fraction of disrupted trophozoites. After heterologous coexpression of alpha19-giardin with giardial N-myristoyltransferase (NMT) in Escherichia coli, we found the protein in a myristoylated form. Additionally, after heterologous expression together with the palmitoyl transferase Pfa3 in Saccharomyces cerevisiae, alpha19-giardin associates with the membrane of the main vacuole. Immunocytochemical colocalization studies on wild-type Giardia trophozoites with tubulin provide evidence that alpha19-giardin exclusively localizes to the ventral pair of the giardial flagella. A mutant in which the putatively myristoylated N-terminal glycine residue was replaced by alanine lost this specific localization. Our findings suggest that the dual lipidation of alpha19-giardin is responsible for its specific flagellar localization.

A Giardia-specific protein family denominated as alpha-giardins, represents the major protein component, besides tubulin, of the cytoskeleton of the human pathogenic parasite Giardia lamblia. One of its members, alpha19-giardin, carries an N-terminal sequence extension of MGCXXS, which in many proteins serves as a target for dual lipid conjugation: myristoylation at the glycine residue after removal of the methionine and palmitoylation at the cysteine residue. As the first experimental evidence of a lipid modification, we found alpha19-giardin to be associated with the membrane fraction of disrupted trophozoites. After heterologous coexpression of alpha19-giardin with giardial N-myristoyltransferase (NMT) in Escherichia coli, we found the protein in a myristoylated form. Additionally, after heterologous expression together with the palmitoyl transferase Pfa3 in Saccharomyces cerevisiae, alpha19-giardin associates with the membrane of the main vacuole. Immunocytochemical colocalization studies on wild-type Giardia trophozoites with tubulin provide evidence that alpha19-giardin exclusively localizes to the ventral pair of the giardial flagella. A mutant in which the putatively myristoylated N-terminal glycine residue was replaced by alanine lost this specific localization. Our findings suggest that the dual lipidation of alpha19-giardin is responsible for its specific flagellar localization.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:05 Vetsuisse Faculty > Institute of Parasitology
04 Faculty of Medicine > Institute of Parasitology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
600 Technology
Language:English
Date:2009
Deposited On:04 Nov 2009 16:04
Last Modified:05 Apr 2016 13:31
Publisher:American Society for Microbiology
ISSN:1535-9786
Additional Information:Copyright: American Society for Microbiology
Publisher DOI:10.1128/EC.00136-09
PubMed ID:19684283
Permanent URL: http://doi.org/10.5167/uzh-23668

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