High-Throughput Discovery of Synthetic Siderophores for Trojan Horse Antibiotics

authored by

Brent S. Weber, Nikki E. Ritchie, Simon Hilker, Derek C.K. Chan, Carsten Peukert, Julia P. Deisinger, Rowan Ives, Christine Årdal, Lori L. Burrows, Mark Brönstrup, Jakob Magolan, Tracy L. Raivio, Eric D. Brown

Abstract

To cause infection, bacterial pathogens must overcome host immune factors and barriers to nutrient acquisition. Reproducing these aspects of host physiology in vitro has shown great promise for antibacterial drug discovery. When used as a bacterial growth medium, human serum replicates several aspects of the host environment, including innate immunity and iron limitation. We previously reported that a high-throughput chemical screen using serum as the growth medium enabled the discovery of novel growth inhibitors overlooked by conventional screens. Here, we report that a subset of compounds from this high-throughput serum screen display an unexpected growth enhancing phenotype and are enriched for synthetic siderophores. We selected 35 compounds of diverse chemical structure and quantified their ability to enhance bacterial growth in human serum. We show that many of these compounds chelate iron, suggesting they were acting as siderophores and providing iron to the bacteria. For two different pharmacophores represented among these synthetic siderophores, conjugation to the β-lactam antibiotic ampicillin imparted iron-dependent enhancement in antibacterial activity. Conjugation of the most potent growth-enhancing synthetic siderophore with the monobactam aztreonam produced MLEB-22043, a broad-spectrum antibiotic with significantly improved activity against Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii, and Pseudomonas aeruginosa. This synthetic siderophore-monobactam conjugate uses multiple TonB-dependent transporters for uptake into P. aeruginosa. Like aztreonam, MLEB-22043 demonstrated activity against metallo-β-lactamase expressing bacteria, and, when combined with the β-lactamase inhibitor avibactam, was active against clinical strains coexpressing the NDM-1 metallo-β-lactamase and serine β-lactamases. Our work shows that human serum is an effective bacterial growth medium for the high-throughput discovery of synthetic siderophores, enabling the development of novel Trojan Horse antibiotics.

Organisation(s)

Institute of Organic Chemistry

External Organisation(s)

McMaster University
Michael G. DeGroote Institute for Infectious Disease Research (IDR)
University of Alberta
Helmholtz Centre for Infection Research (HZI)
Norwegian Institute of Public Health
German Center for Infection Research (DZIF)

Type

Article

Journal

ACS infectious diseases

Volume

10

Pages

3821-3841

No. of pages

21

ISSN

2373-8227

Publication date

08.11.2024

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Infectious Diseases

Sustainable Development Goals

SDG 3 - Good Health and Well-being

Electronic version(s)

https://doi.org/10.1021/acsinfecdis.4c00359 (Access: Closed)