Indiana University-Purdue University Indianapolis (IUPUI) / The pathogenesis associated with toxoplasmosis is attributed to repeated rounds
of the parasite lytic cycle, which has been shown to be regulated by calcium fluxes.
However, little is known about the calcium homeostatic mechanisms utilized by T.
gondii. Recently, our lab has identified a novel protein-TgEFP1 (TGGT1_255660),
which is predicted to bind Ca2+ through its two EF-hand domains. Interestingly, TgEFP1
showed a unique dual localization at the PLV/ELC and the PV of the parasite. Previous
work showed that the PLV/ELC harbors other ion binding and conducting proteins that
are important for parasite survival and propagation. However, the function of this
compartment in the parasite is unknown. Therefore, I hypothesize that the PLV/ELC,
through the function of TgEFP1, plays a key role in calcium homeostasis of T. gondii.
To test this hypothesis, we sought to characterize the function of TgEFP1 during
the parasite lytic cycle and determine TgEFP1 interacting proteins that also localize to the
PLV/ELC. Partial permeabilization and ultrastructure expansion microscopy techniques
confirmed the dual localization of TgEFP1 at the PLV/ELC and the PV. TgEFP1
knockout parasites exhibited several phenotypic defects including a faster lytic rate,
shorter intracellular cycle, and were more sensitive to calcium ionophore treatment.
Signal peptide deletion led to a mislocalization of TgEFP1 as cytosolic puncta, while
mutations at key calcium coordinating residues lead to exclusive localization of TgEFP1
at the PV. Lastly, immunoprecipitation assays followed by LC-MS/MS identified a novel lectin-like protein- TgLectin (TGGT1_258950) as a direct interactor of TgEFP1-HA.
Collectively, these findings support that through the function of TgEFP1, the PLV/ELC,
plays a key role in calcium-dependent processes during the lytic cycle of the parasite.
| Identifer | oai:union.ndltd.org:IUPUI/oai:scholarworks.iupui.edu:1805/29837 |
| Date | 08 1900 |
| Creators | Dave, Noopur Kirti |
| Contributors | Arrizabalaga, Gustavo, Absalon, Sabrina, Fehrenbacher, Jill, Gilk, Stacey, Jerde, Travis, Mastracci, Teresa |
| Source Sets | Indiana University-Purdue University Indianapolis |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
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