Dual Acylation Accounts for the Localization of alpha 19-Giardin in the Ventral Flagellum Pair of Giardia lamblia

Autor(en): Saric, Mirela
Vahrmann, Anke
Niebur, Daniela
Kluempers, Verena
Hehl, Adrian B.
Scholze, Henning
Stichwörter: ANNEXIN; BOUND CRYSTAL-STRUCTURES; HOMOLOG; IDENTIFICATION; INTESTINALIS; Microbiology; Mycology; N-MYRISTOYLATION; PROTEIN PALMITOYLATION; SEQUENCE; SURFACE PROTEIN; VACUOLE
Erscheinungsdatum: 2009
Herausgeber: AMER SOC MICROBIOLOGY
Journal: EUKARYOTIC CELL
Volumen: 8
Ausgabe: 10
Startseite: 1567
Seitenende: 1574
Zusammenfassung: 
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, alpha 19-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 alpha 19-giardin to be associated with the membrane fraction of disrupted trophozoites. After heterologous coexpression of alpha 19-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, alpha 19-giardin associates with the membrane of the main vacuole. Immunocytochemical colocalization studies on wild-type Giardia trophozoites with tubulin provide evidence that alpha 19-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 alpha 19-giardin is responsible for its specific flagellar localization.
ISSN: 15359778
DOI: 10.1128/EC.00136-09

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