# Characterizing the unique endocytic organelle of Trypanosoma cruzi

> **NIH NIH R21** · UNIVERSITY OF GEORGIA · 2020 · $226,500

## Abstract

PROJECT SUMMARY
The etiological agent of Chagas disease, Trypanosoma cruzi, is an obligate intracellular parasite that infects an
estimated 10 million people in the Americas, with an at-risk population of 70 million. While the acute infection
by the parasite is effectively controlled by the immune system, a chronic infection can persist for the lifetime of
the host. Despite its recognition as the highest impact parasitic infection of the Americas, Chagas disease
remains underreported, understudied and underfunded. Basic research into the biology of T. cruzi has been
previously hindered by a lack of efficient genetic tools, but the advent of CRISPR/Cas9 gene editing
technology has cleared the way for more in-depth molecular analyses. The primary interface between T. cruzi
and its mammalian hosts is at the level of the replicative intracellular amastigotes in the cytoplasm of infected
host cells. Trypanosoma cruzi is one of only a few protozoan pathogens that live and replicate directly in the
cytosol of nucleated cells. Of the (mostly bacterial) pathogens that can inhabit the host cytosol, many have
been shown to actively induce host cytosolic protein degradation in order to obtain energy and amino acids
which are normally limiting in the cytoplasm. A long-standing mystery is how T. cruzi is able to extract
necessary nutrients from this impoverished environment? Unlike other parasites, T. cruzi has the ability to
endocytose and digest host cytosolic material via a long tubular invagination (cytopharynx) starting at a surface
plasma membrane pore (cytostome). This structure, referred to here as the cytostome/cytopharynx or CSP
complex, is present only in replicating forms of the T. cruzi and disassembles during the transition to
trypomastigote stages. The CSP structure, which has been examined extensively using electron tomography
techniques, has resisted molecular analysis, as the protein components comprising it have remained elusive.
We have recently identified the first protein targeted solely to the CSP structure, CP1, and our preliminary work
has shown that this protein colocalizes with endocytosed cargo in the CSP. In this proposal, we will use CP1 to
carry out the first in-depth characterization of the T. cruzi CSP. We will fuse CP1 to the BioID biotin ligase and
perform proximity labeling of the CSP to identify its protein components. A selected subset of the identified
components will be validated by endogenous tagging and assessed for their role in parasite feeding, replication
and survival. Additionally, we will extend our analysis of the host cell components taken up in the CSP to
determine the selectively with respect to host proteins or organelles during intracellular amastigote replication.
Completion of this study will allow us to begin analyzing in detail a unique, but crucial, aspect of T. cruzi
parasitism which previously resisted in-depth investigation.

## Key facts

- **NIH application ID:** 9932346
- **Project number:** 5R21AI146447-02
- **Recipient organization:** UNIVERSITY OF GEORGIA
- **Principal Investigator:** RONALD DREW ETHERIDGE
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $226,500
- **Award type:** 5
- **Project period:** 2019-05-21 → 2022-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9932346

## Citation

> US National Institutes of Health, RePORTER application 9932346, Characterizing the unique endocytic organelle of Trypanosoma cruzi (5R21AI146447-02). Retrieved via AI Analytics 2026-06-11 from https://api.ai-analytics.org/grant/nih/9932346. Licensed CC0.

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