Bicyclic azetidines kill the diarrheal pathogen Cryptosporidium in mice by inhibiting parasite phenylalanyl-tRNA synthetase PMID: 32998973

RQC and Longevity Regulation

2026-09-03

Bicyclic azetidines kill the diarrheal pathogen Cryptosporidium in mice by inhibiting parasite phenylalanyl-tRNA synthetase

Sci Transl Med. 2020 Sep 30;12(563):eaba8412. doi: 10.1126/scitranslmed.aba8412.

Sumiti Vinayak ¹ , Rajiv S Jumani ² , Peter Miller ³ , Muhammad M Hasan ² , Briana I McLeod ⁴ , Jayesh Tandel ⁴ , Erin E Stebbins ³ , Jose E Teixeira ³ , Julien Borrel ⁵ , Arthur Gonse ⁵ , Mingliang Zhang ⁶ , Xianshui Yu ⁶ , Amy Wernimont ⁷ , Chris Walpole ⁷ , Sean Eckley ⁸ , Melissa S Love ⁹ , Case W McNamara ⁹ , Manmohan Sharma ¹⁰ , Amit Sharma ¹⁰ , Christina A Scherer ⁵ , Nobutaka Kato ⁵ , Stuart L Schreiber ⁵ ¹¹ , Bruno Melillo ⁵ ¹¹ ¹² , Boris Striepen ¹³ , Christopher D Huston ¹⁴ , Eamon Comer ¹⁵

Affiliations

1. Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA.
2. Cellular, Molecular and Biomedical Sciences Graduate Program, University of Vermont, Burlington, VT 05405, USA.
3. Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, VT 05405, USA.
4. Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
5. Chemical Biology and Therapeutics Science Program, Broad Institute, Cambridge, MA 02142, USA.
6. International Discovery Service Unit, WuXi AppTec (Tianjin) Co. Ltd., Tianjin 300457, P.R. China.
7. Structural Genomics Consortium, MaRS Building, South Tower, 101 College Street, Suite 700, Toronto, Ontario M5G 1L7, Canada.
8. Eisai Inc., Cambridge, MA 02140, USA.
9. Calibr, a division of The Scripps Research Institute, La Jolla, CA 92037, USA.
10. Structural Parasitology, Molecular Medicine Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Road, New Delhi 110070, India.
11. Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
12. Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, USA.
13. Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. [email protected] [email protected] [email protected].
14. Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, VT 05405, USA. [email protected] [email protected] [email protected].
15. Chemical Biology and Therapeutics Science Program, Broad Institute, Cambridge, MA 02142, USA. [email protected] [email protected] [email protected].

Abstract

Cryptosporidium is a protozoan Parasite and a leading cause of diarrheal disease and mortality in young children. Currently, there are no fully effective treatments available to cure Infection with this diarrheal pathogen. In this study, we report a broad drug repositioning effort that led to the identification of bicyclic azetidines as a new anticryptosporidial series. Members of this series blocked growth in in vitro culture of three Cryptosporidium parvum isolates with EC₅₀ ^'s in 1% serum of <0.4 to 96 nM, had comparable potencies against Cryptosporidium hominis and C. parvum, and was effective in three of four highly susceptible immunosuppressed mice with once-daily dosing administered for 4 days beginning 2 weeks after Infection. Comprehensive genetic, biochemical, and chemical studies demonstrated inhibition of C. parvum phenylalanyl-tRNA synthetase (CpPheRS) as the mode of action of this new lead series. Introduction of mutations directly into the C. parvum pheRS gene by CRISPR-Cas9 genome editing resulted in parasites showing high degrees of compound resistance. In vitro, bicyclic azetidines potently inhibited the aminoacylation activity of Recombinant ChPheRS. Medicinal chemistry optimization led to the identification of an optimal pharmacokinetic/pharmacodynamic profile for this series. Collectively, these data demonstrate that bicyclic azetidines are a promising series for anticryptosporidial drug development and establish a broad framework to enable target-based drug discovery for this infectious disease.