Unique composition and hyperstability of the ventral disc, Giardias complex microtubule organelle

Giardia is a common protistan parasite that causes diarrheal disease worldwide. Motile trophozoites colonize the small intestine, attaching to the villi with the ventral disc, a unique and complex microtubule (MT) organelle. Attachment to the host epithelium allows Giardia to resist peristalsis duri...

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Bibliographic Details
Published inbioRxiv
Main Authors Nosala, Christopher, Hagen, Kari D, Jones, Kelci, Loudermilk, Rita, Nguyen, Kristofer, Dawson, Scott C
Format Paper
LanguageEnglish
Published Cold Spring Harbor Cold Spring Harbor Laboratory Press 09.10.2018
Subjects
Ankyrins
Basal bodies
Cytoplasm
Diarrhea
Epithelium
Flagella
Gastrointestinal tract
Genetic analysis
Homology
Peristalsis
Potassium chloride
Protein arrays
Proteins
Small intestine
Trophozoites
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Summary:Giardia is a common protistan parasite that causes diarrheal disease worldwide. Motile trophozoites colonize the small intestine, attaching to the villi with the ventral disc, a unique and complex microtubule (MT) organelle. Attachment to the host epithelium allows Giardia to resist peristalsis during infection of the host gastrointestinal tract. Despite our emerging view of the complexity of ventral disc architecture, we are still in the very preliminary stages of understanding how specific structural elements contribute to disc stability or generate forces for attachment. The ventral disc is a large, dome-shaped, spiral MT array decorated with microribbon-crossbridge protein complexes (MR-CB) that extend upward into the cytoplasm. Using a new high salt method for disc biochemical fractionation followed by shotgun proteomic analyses and validation by GFP-tagging, we identified 54 new disc-associated proteins (DAPs). Of 87 DAPs confirmed to date, 54 localize only to the disc, and the remainder localize to additional structures such as the flagella, basal bodies, or median body. Almost one third of DAPs lack any homology to proteins in other eukaryotes and another one third simply contain ankyrin repeat domains. Many DAPs localize to specific structural regions of the disc, including the ventral groove region and disc margin. We also demonstrate that the disc is a stable structure lacking canonical MT dynamic instability and show that the disc structure and composition remain intact after detergent extraction in up to 2M potassium chloride. Future genetic, biochemical, and functional analyses of DAPs will be central toward understanding disc architecture, assembly and dynamics. Footnotes * Revised text and all figures
DOI:10.1101/361105