# Exploring the function of a novel tyrosine kinase like (TKL) protein in Toxoplasma endodyogeny

> **NIH NIH R21** · VIRGINIA POLYTECHNIC INST AND ST UNIV · 2022 · $200,000

## Abstract

PROJECT SUMMARY/ABSTRACT
Toxoplasma gondii is an important human pathogen that divides by a unique mode of cell division
called endodyogeny that is quite distinct from binary fission that occurs in mammalian cells. Since
Toxoplasma division is divergent from higher eukaryotes, a better understanding of this complex
process and identification of its key components and their mode of regulation would potentially
open doors for selective strategies to disrupt infection. TgTKL4 is a member of tyrosine kinase
like (TKL) family protein in Toxoplasma that localizes to parasite cytoplasm with its expression
mainly confined to synthesis (S), mitosis/cytokinesis (M/C) phases of the cell cycle. Interestingly,
loss of this kinase causes defects in cell division that results in misshapen parasites with
compromised fitness and attenuated virulence. Specifically, TgTKL4 null mutants with abnormal
morphology display significant defects in in vitro propagation suggesting loss of this kinase affects
one or more stages of Toxoplasma lytic cycle. Since TgTKL4 is a cell-cycle regulated kinase and
parasites deficient in this enzyme show abnormal shape, we hypothesize that this kinase is a part
of the signaling network that dictates parasite morphology during endodyogeny. To further
understand the role of this novel TKL kinase in parasite replication, we propose to: (1) Identify
substrates of TgTKL4; and (2) Determine the role of TgTKL4 in Toxoplasma endodyogeny. Thus,
our proposed work will help us understand the precise function of TgTKL4 and signaling network
associated with this kinase during cell division that determines parasite morphology.

## Key facts

- **NIH application ID:** 10451021
- **Project number:** 1R21AI162606-01A1
- **Recipient organization:** VIRGINIA POLYTECHNIC INST AND ST UNIV
- **Principal Investigator:** Rajshekhar Gaji
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $200,000
- **Award type:** 1
- **Project period:** 2022-05-03 → 2024-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10451021

## Citation

> US National Institutes of Health, RePORTER application 10451021, Exploring the function of a novel tyrosine kinase like (TKL) protein in Toxoplasma endodyogeny (1R21AI162606-01A1). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10451021. Licensed CC0.

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