# Cryptosporidium's polyketide secondary metabolite: exogenous production, compound characterization and function in intracellular development.

> **NIH NIH R21** · UNIVERSITY OF MINNESOTA · 2022 · $224,014

## Abstract

Cryptosporidium is a ubiquitous water-born protozoal pathogen that causes diarrheal disease world-wide. Since
there are neither vaccines nor effective therapeutics to treat this disease, and very few drugs in the pipeline,
identification of new druggable targets is imperative. Encoded within the Cryptosporidium genome is a single
polyketide synthase, CpPKS1. Polyketide synthases, found widely in bacteria, fungi, protozoa, and plants,
synthesize polyketide secondary metabolites that exhibit a remarkable diversity of chemical structures and
biologic functions, presumably providing the producing organism with some survival advantage. CpPKS1 is
upregulated during intracellular infection but the molecule it synthesizes, and the function of this molecule,
remain unknown. Our approach to investigating the role of the Cryptosporidium polyketide began with
heterologous expression of cpPKS1 in Aspergillus which produced two unique metabolites. In this R21
application we propose to optimize expression of CpPKS1 in this system, characterize the structure of this
molecule and explore its function in Cryptosporidium host-parasite interactions. Because of the many biological
activities possessed by polyketides, we broadly hypothesize that CpPK1 plays a critical role in either parasite
development and/or host parasite interactions. We will test this hypothesis through the completion of two specific
aims.
Aim 1: Isolate the Cryptosporidium metabolite produced in Aspergillus and elucidate the structure of
the metabolite. In our preliminary expression of cpPKS1 in A. nidulans the putative CpPK1 metabolites were
not in high enough concentration to purify. Here we will express cpPKS1 in SMs- strains of A. nidulans to reduce
interference from endogenous metabolites. Metabolites will be validated and purified using liquid
chromatography-mass spectrometry and NMR spectroscopy.
Aim 2: To ablate synthesis of the Cp polyketide metabolite and examine the effects of its absence on
parasite development and host and parasite transcriptomes. In these studies, we will inhibit the synthesis
of CpPK1 using a newly described conditional knockout system and explore the resulting changes to parasite
development in an organoid system that supports the complete parasite life cycle (2A). Changes in host and
parasite transcriptome due to the absence of CpPK1 will be evaluated by RNAseq (2B).
These studies employ highly innovative techniques from the fields of parasitology and natural product chemistry
to explore the function of a molecule unique to Cryptosporidium that could be fundamental to parasite biology.
Should CpPK1 prove essential for parasite development, future studies will examine the potential for therapeutic
inhibition of the synthase. If the molecule is involved in host and parasite interactions, the RNAseq studies will
provide preliminary data for targeted investigations.

## Key facts

- **NIH application ID:** 10354414
- **Project number:** 1R21AI166564-01
- **Recipient organization:** UNIVERSITY OF MINNESOTA
- **Principal Investigator:** NANCY P KELLER
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $224,014
- **Award type:** 1
- **Project period:** 2022-07-01 → 2024-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10354414

## Citation

> US National Institutes of Health, RePORTER application 10354414, Cryptosporidium's polyketide secondary metabolite: exogenous production, compound characterization and function in intracellular development. (1R21AI166564-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10354414. Licensed CC0.

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