Open AccessBicyclic azetidines kill the diarrheal pathogen Cryptosporidium in mice by inhibiting parasite phenylalanyl-tRNA synthetase
Author(s) -
Sumiti Vinayak,
Rajiv S. Jumani,
Peter J. Miller,
Muhammad Mahmudul Hasan,
Briana I. McLeod,
Jayesh Tandel,
Erin E. Stebbins,
José E. Teixeira,
Julien Borrel,
Arthur Gonse,
Mingliang Zhang,
Xianshui Yu,
A.K. Wernimont,
Chris Walpole,
Sean Eckley,
Melissa S. Love,
Case W. McNamara,
Manmohan Sharma,
Amit Sharma,
Christina Scherer,
Nobutaka Kato,
Stuart L. Schreiber,
Bruno Melillo,
Boris Striepen,
Christopher D. Huston,
Eamon Comer
Publication year - 2020
Publication title -
science translational medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.819
H-Index - 216
eISSN - 1946-6242
pISSN - 1946-6234
DOI - 10.1126/scitranslmed.aba8412
Subject(s) - cryptosporidium , parasite hosting , pathogen , biology , microbiology and biotechnology , virology , chemistry , feces , world wide web , computer science
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 EC 50 ' 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 ( Cp PheRS) 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 Ch PheRS. 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.