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The opportunistic pathogen Toxoplasma gondii deploys a diverse legion of invasion and survival proteins.

TitleThe opportunistic pathogen Toxoplasma gondii deploys a diverse legion of invasion and survival proteins.
Publication TypeJournal Article
Year of Publication2005
AuthorsZhou XW, Kafsack BFC, Cole RN, Beckett P, Shen RF, Carruthers VB
JournalJ Biol Chem
Volume280
Issue40
Pagination34233-44
Date Published2005 Oct 07
ISSN0021-9258
KeywordsAnimals, Electrophoresis, Gel, Two-Dimensional, Mass Spectrometry, Protozoan Proteins, Spectrometry, Mass, Electrospray Ionization, Survival, Toxoplasma, Toxoplasmosis
Abstract

Host cell invasion is an essential step during infection by Toxoplasma gondii, an intracellular protozoan that causes the severe opportunistic disease toxoplasmosis in humans. Recent evidence strongly suggests that proteins discharged from Toxoplasma apical secretory organelles (micronemes, dense granules, and rhoptries) play key roles in host cell invasion and survival during infection. However, to date, only a limited number of secretory proteins have been discovered, and the full spectrum of effector molecules involved in parasite invasion and survival remains unknown. To address these issues, we analyzed a large cohort of freely released Toxoplasma secretory proteins by using two complementary methodologies, two-dimensional electrophoresis/mass spectrometry and liquid chromatography/electrospray ionization-tandem mass spectrometry (MudPIT, shotgun proteomics). Visualization of Toxoplasma secretory products by two-dimensional electrophoresis revealed approximately 100 spots, most of which were successfully identified by protein microsequencing or matrix-assisted laser desorption ionization-mass spectrometry analysis. Many proteins were present in multiple species suggesting they are subjected to substantial post-translational modification. Shotgun proteomic analysis of the secretory fraction revealed several additional products, including novel putative adhesive proteins, proteases, and hypothetical secretory proteins similar to products expressed by other related parasites including Plasmodium, the etiologic agent of malaria. A subset of novel proteins were re-expressed as fusions to yellow fluorescent protein, and this initial screen revealed shared and distinct localizations within secretory compartments of T. gondii tachyzoites. These findings provided a uniquely broad view of Toxoplasma secretory proteins that participate in parasite survival and pathogenesis during infection.

DOI10.1074/jbc.M504160200
Alternate JournalJ Biol Chem
PubMed ID16002397
PubMed Central IDPMC1360232
Grant ListR01 AI046675 / AI / NIAID NIH HHS / United States
R21 AI053797 / AI / NIAID NIH HHS / United States
1S10-RR14702 / RR / NCRR NIH HHS / United States
R21AI053797 / AI / NIAID NIH HHS / United States

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