# Proline homeostasis: a novel mediator of drug tolerance in Plasmodium falciparum

> **NIH NIH R01** · HARVARD UNIVERSITY D/B/A HARVARD SCHOOL OF PUBLIC HEALTH · 2024 · $699,605

## Abstract

PROJECT SUMMARY
Sustained availability of efficacious drugs is essential for worldwide efforts to eradicate malaria. The emergence
and spread of drug resistance to current antimalarial therapies remains a pressing concern with reports of
artemisinin-based treatment failures escalating the need for novel antimalarial chemotherapies. Thus the
discovery of new druggable targets and pathways, including those that are critical for multiple life stages, is a
major challenge for the development of next-generation therapeutics.
Using an integrated chemogenomic approach, we have identified the cytoplasmic prolyl tRNA synthetase in
Plasmodium falciparum (PfcPRS) as the long-sought biochemical target of halofuginone. Furthermore, we
uncovered an unprecedented mechanism of drug-tolerance in the parasite by modulation of proline homeostasis.
In this proposal, we seek to understand the molecular basis of the parasite’s ability to sense and evolve
resistance to halofuginone via the Adaptive Proline Response (APR). We bring an integrated approach
combining our expertise in molecular parasitology, metabolomics, genetics, and synthetic chemistry to probe
these aspects of aminoacyl tRNA synthetase biology and inhibition in the parasite.
We will investigate a non-genetic mechanism of resistance to the PfcPRS inhibitor, halofuginone. We identify
the primary source of increased intracellular proline in response to halofuginone treatment and strategies
to circumvent this process.
We will determine if increased proline levels in parasites exhibiting the APR are mediated by changes in
key metabolic pathways at the genomic or proteomic level, using high-coverage DNA sequencing and
quantitative mass spectrometry-based proteomic technologies.
We will explore APR-independent mechanisms of aaRS inhibition in the parasite, evaluating PRS inhibitors
with differing binding modes.

## Key facts

- **NIH application ID:** 10795877
- **Project number:** 5R01AI143723-05
- **Recipient organization:** HARVARD UNIVERSITY D/B/A HARVARD SCHOOL OF PUBLIC HEALTH
- **Principal Investigator:** Ralph Mazitschek
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $699,605
- **Award type:** 5
- **Project period:** 2020-04-01 → 2025-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10795877

## Citation

> US National Institutes of Health, RePORTER application 10795877, Proline homeostasis: a novel mediator of drug tolerance in Plasmodium falciparum (5R01AI143723-05). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10795877. Licensed CC0.

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