# Discovery and optimization of antifungal acetyl CoA synthetase inhibitors

> **NIH NIH R01** · UNIVERSITY OF IOWA · 2021 · $599,458

## Abstract

PROJECT SUMMARY
Recently, we discovered that a small molecule inhibitor of acetyl CoA synthetase (ACS), AR-12, has broad
spectrum fungicidal activity in vitro and promising activity in vivo. Consistent with this broad spectrum of activity,
genetic studies indicate that ACS is essential for viability in multiple fungi (C. albicans, Fusarium, S. cerevisiae).
In contrast, ACS is not essential in mammals. This is likely because, in mammals and plants, the vast majority
of acetyl CoA is derived from ATP-citrate lyase (ACL) and not ACS. The most important exception to this rule is
the cancer cell where ACS is the predominant source of acetyl CoA. Consequently, ACS has emerged as an
anti-cancer target. Although the development of AR-12 stalled, we propose that its target, ACS, remains worthy
of further exploration as the basis for a new class of antifungal drugs.To identify novel inhibitors of fungal ACSs,
we have developed a multi-disciplinary approach based on: 1) two complementary small molecule screening
strategies; 2) the structural characterization ACS-inhibitor complexes from multiple pathogenic fungi: 3) whole
cell assays of ACS function and inhibition, and 4) medicinal chemistry strategies that have already yielded
micromolar inhibitors of ACS. An STD-NMR screen with C. neoformans Acs1 and identified 492 ACS interacting
molecular fragments, of which the vast majority also interacted with multiple fungal ACS enzymes. In Aim 1, we
will further characterize these hits. As a parallel strategy, we adapted our ACS activity assay for high throughput
screening (HTS) with the goal of directly identifying small molecule ACS inhibitors. Our chemistry plan (Aim 2)
is guided, in part, by the hypothesis that molecules mimicking the acetyl adenosine-monophosphate ester
(AcAMP) intermediate are likely to be effective inhibitors. In Aim 2A, we will characterize the acetyl-PO3 binding
pocket by a structure-activity study of AcAMP mimics derived from molecules already crystallized in the active
site of fungal ACSs. Biochemically stable, potent acetyl-PO3 isosteres emerging from this analysis will then be
linked with putative ATP/AMP-binding pocket-targeted fragments to assemble candidate non-nucleoside, bi-
substrate ACS inhibitors. To complement this hypothesis-based strategy, candidate inhibitors will also be
assembled from other strongly interacting fragments and we will optimize inhibitors directly identified in the ACS
activity-based HTS screen (Aims 2B&C). New molecules will be evaluated (Aim 3) with a testing funnel that
includes biochemical characterization of ACS inhibition, antifungal activity against a range of pathogenic fungi,
whole cell assays of on-target activity against ACS, and initial in vitro toxicity/ADME characterization. Our goal
is to identify a lead ACS inhibitor scaffold along with a back-up series for further pre-clinical development as
broad-spectrum antifungal drug candidates.

## Key facts

- **NIH application ID:** 10241688
- **Project number:** 1R01AI161973-01
- **Recipient organization:** UNIVERSITY OF IOWA
- **Principal Investigator:** Damian J Krysan
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $599,458
- **Award type:** 1
- **Project period:** 2021-07-09 → 2026-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10241688

## Citation

> US National Institutes of Health, RePORTER application 10241688, Discovery and optimization of antifungal acetyl CoA synthetase inhibitors (1R01AI161973-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10241688. Licensed CC0.

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