# POLYAMINE AND TRYPANOTHIONE METABOLISM IN TRYPANOSOMA BRUCEI

> **NIH NIH R01** · UT SOUTHWESTERN MEDICAL CENTER · 2020 · $444,276

## Abstract

Project Summary
This proposal represents the continuation of our long-running program to understand the biology of polyamine
metabolism in the trypanosomatid parasites and to exploit the pathway for drug discovery. Trypanosomatids
are the causative agents of human African trypanosomiasis (HAT), Leishmaniasis and Chagas disease, all of
which are listed by the WHO as neglected tropical diseases (NTDs). Collectively 18-20 million people are
infected with one of these parasites, yet drug therapies remain inadequate for all three diseases. Polyamines
are small organic polycations that are synthesized from L-ornithine and S-adenosylmethionine. In eukaryotes,
the polyamine spermidine is absolutely essential for growth due to its role as a substrate for the hypusine
modification of the translation factor eIF5A. Eflornithine, which inhibits the polyamine biosynthetic enzyme
ornithine decarboxylase (ODC), is a frontline therapy for the treatment of HAT. Interest in understanding the
biology and regulatory mechanisms of this pathway led to the finding that, while the trypanosomatids share in
common the essential role for hypusination, they have evolved both unique polyamine-containing metabolites
and their own regulatory strategies in comparison to other eukaryotic cells. This includes our discovery that two
of the biosynthetic enzymes S-adenosylmethionine decarboxylase (AdoMetDC) and deoxyhypusine synthase
(DHS) each require oligomerization with inactive pseudoenzmes for activity. Despite significant understanding
of the metabolism and biological roles of polyamines in trypanosomatids, a number of key questions remain
unexplored and are the subject of this proposal. In Aim 1, we plan studies to build on our observation that the
AdoMetDC pseudoenzyme (termed prozyme) is translationally regulated in response to perturbations that
reduce levels of the product decarboxylated AdoMet, suggesting dcAdoMet functions as a novel metabolic
signal for regulation of the polyamine pathway. In Aim 2, we will focus on unexplored metabolic pathways and
functional roles of the upstream polyamine metabolites L-Orn and Put. Our questions are: does Put play
additional roles beyond its requirement as a precursor for Spd synthesis; and can T. brucei synthesize L-Orn
using an uncharacterized amidinotransferase. In Aim 3, we will study the function and composition of enzymes
(DHS and deoxyhypusine hydroxylase (DOHH)) required to modify eIF5A with the hypusine cofactor. Our
approaches will be a combination of genetic strategies and pharmacologic tools to perturb cell metabolism, state
of the art metabolomics, genomic strategies to identify candidate genes, and biochemistry (protein expression,
enzyme assay and crystallography). While our work will focus on T. brucei, the unusual metabolic features of
this pathway have been found in all three pathogenic trypanosomatids, so it is likely that the discoveries we
make in T. brucei will translate to T. cruzi and Leishmania. Finally, whil...

## Key facts

- **NIH application ID:** 10047757
- **Project number:** 2R01AI034432-25A1
- **Recipient organization:** UT SOUTHWESTERN MEDICAL CENTER
- **Principal Investigator:** Margaret A. Phillips
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $444,276
- **Award type:** 2
- **Project period:** 1994-12-01 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10047757

## Citation

> US National Institutes of Health, RePORTER application 10047757, POLYAMINE AND TRYPANOTHIONE METABOLISM IN TRYPANOSOMA BRUCEI (2R01AI034432-25A1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10047757. Licensed CC0.

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