title: Mutations in genes for the F420 biosynthetic pathway and a nitroreductase enzyme are the primary resistance determinants in spontaneous in vitro-selected PA-824-resistant mutants of Mycobacterium tuberculosis.
abstract: Alleviating the burden of tuberculosis (TB) requires an understanding of the genetic basis that determines the emergence of drug-resistant mutants. PA-824 (pretomanid) is a bicyclic nitroimidazole class compound presently undergoing the phase III STAND clinical trial, despite lacking identifiable genetic markers for drug-specific resistant Mycobacterium tuberculosis. In the present study, we aimed to characterize the genetic polymorphisms of spontaneously generated PA-824-resistant mutant strains by surveying drug metabolism genes for potential mutations. Of the 183 independently selected PA-824-resistant M. tuberculosis mutants, 83% harbored a single mutation in one of five nonessential genes associated with either PA-824 prodrug activation (ddn, 29%; fgd1, 7%) or the tangential F420 biosynthetic pathway (fbiA, 19%; fbiB, 2%; fbiC, 26%). Crystal structure analysis indicated that identified mutations were specifically located within the protein catalytic domain that would hinder the activity of the enzymes required for prodrug activation. This systematic analysis conducted of genotypes resistant to PA-824 may contribute to future efforts in monitoring clinical strain susceptibility with this new drug therapy.
authors.affiliation: Novartis Institute for Tropical Diseases, Singapore Department of Microbiology and Immunology Program, Yong Loo Lin School of Medicine, Life Sciences Institute, National University of Singapore, Singapore.
authors.forename: Hana L
authors.initials: HL
authors.lastname: Haver
authors.affiliation: Novartis Institute for Tropical Diseases, Singapore.
authors.forename: Adeline
authors.initials: A
authors.lastname: Chua
authors.affiliation: Novartis Institute for Tropical Diseases, Singapore Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore.
authors.forename: Pramila
authors.initials: P
authors.lastname: Ghode
authors.affiliation: Novartis Institute for Tropical Diseases, Singapore.
authors.forename: Suresh B
authors.initials: SB
authors.lastname: Lakshminarayana
authors.affiliation: Singapore Immunology Network (SIgN), A*STAR, Singapore.
authors.forename: Amit
authors.initials: A
authors.lastname: Singhal
authors.affiliation: Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, USA.
authors.forename: Barun
authors.initials: B
authors.lastname: Mathema
authors.affiliation: Laboratory of Biopolymers and Supramolecular Nanomaterials (CP206/04), Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: René
authors.initials: R
authors.lastname: Wintjens
authors.affiliation: Novartis Institute for Tropical Diseases, Singapore pablo.bifani@novartis.com.
authors.forename: Pablo
authors.initials: P
authors.lastname: Bifani
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000235:genetics; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics; D009593:Nitroimidazoles / Q000494:pharmacology*; D009601:Nitroreductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D011110:Polymorphism, Genetic / Q000235:genetics; D017433:Protein Structure, Secondary
chemical_list: D000995:Antitubercular Agents; D001426:Bacterial Proteins; D009593:Nitroimidazoles; C410767:pretomanid; D009601:Nitroreductases