# The role of acetate fermentation in Entamoeba histolytica growth and infection

> **NIH NIH P20** · CLEMSON UNIVERSITY · 2020 · $220,919

## Abstract

PROJECT SUMMARY
The pathogenic protist Entamoeba histolytica is estimated to be responsible for 50,000 to 100,000 deaths each
year and is a significant source of morbidity and mortality due to parasitic disease in humans, particularly in
developing countries. This protist is also listed by NIAID as a category B priority pathogen with bioterrorism
potential due to its low infectious dose and potential for dissemination through compromised food and water
supplies. E. histolytica has a simple life cycle, existing in either an infectious cyst form or as motile trophozoites
which can reside in the anaerobic confines of the human colon. This microbe is a scavenger that lacks ATP-
producing mitochondria and relies on glycolysis as its primary pathway for generation of ATP. The PPi-
dependent glycolytic pathway of Entamoeba has an increased net generation of ATP, which would be
beneficial for organisms that lack a functional citric acid cycle and oxidative phosphorylation and must rely
solely on substrate level phosphorylation to generate ATP from glucose breakdown. The proposed research
examines the role of acetate fermentation in E. histolytica energy metabolism and physiology. Acetate is
produced during growth in axenic culture, and the two enzymes of interest, acetate kinase (Ack) and ADP-
forming acetyl-CoA synthetase (Acd), are both proposed to play a role in acetate production at the end of
glycolysis. Acd is proposed to provide for generation of an additional ATP at the end of glycolysis.
Recombinant E. histolytica Acd (EhAcd) has been shown to function well in both directions of the reaction,
suggesting that this enzyme can operate in either direction in vivo, depending on the cell's metabolic needs.
Recombinant E. histolytica Ack (EhAck) has been shown to have two unusual properties: production of PPi
rather than ATP, and a strong preference for the acetate-forming direction of the reaction. Ack may thus
provide a mechanism for supplying additional PPi for glycolysis under certain growth conditions that require a
higher flux through this pathway. The two specific aims of this proposal are (1) to investigate the enzymology of
EhAcd and EhAck using a structure-function approach; and (2) to determine the physiological roles of Acd and
Ack in E. histolytica through transcriptome profiling and metabolic analysis of ACK and ACD RNAi and
overexpression strains. The results from this research will provide a better understanding of a key metabolic
pathway for ATP generation in this important eukaryotic pathogen.

## Key facts

- **NIH application ID:** 9900819
- **Project number:** 5P20GM109094-05
- **Recipient organization:** CLEMSON UNIVERSITY
- **Principal Investigator:** CHERYL Jean INGRAM-SMITH
- **Activity code:** P20 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $220,919
- **Award type:** 5
- **Project period:** — → 2022-07-14

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9900819

## Citation

> US National Institutes of Health, RePORTER application 9900819, The role of acetate fermentation in Entamoeba histolytica growth and infection (5P20GM109094-05). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/9900819. Licensed CC0.

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