title: First-in-Class Inhibitors of Sulfur Metabolism with Bactericidal Activity against Non-Replicating M. tuberculosis.
abstract: Development of effective therapies to eradicate persistent, slowly replicating M. tuberculosis (Mtb) represents a significant challenge to controlling the global TB epidemic. To develop such therapies, it is imperative to translate information from metabolome and proteome adaptations of persistent Mtb into the drug discovery screening platforms. To this end, reductive sulfur metabolism is genetically and pharmacologically implicated in survival, pathogenesis, and redox homeostasis of persistent Mtb. Therefore, inhibitors of this pathway are expected to serve as powerful tools in its preclinical and clinical validation as a therapeutic target for eradicating persisters. Here, we establish a first functional HTS platform for identification of APS reductase (APSR) inhibitors, a critical enzyme in the assimilation of sulfate for the biosynthesis of cysteine and other essential sulfur-containing molecules. Our HTS campaign involving 38 350 compounds led to the discovery of three distinct structural classes of APSR inhibitors. A class of bioactive compounds with known pharmacology displayed potent bactericidal activity in wild-type Mtb as well as MDR and XDR clinical isolates. Top compounds showed markedly diminished potency in a conditional ΔAPSR mutant, which could be restored by complementation with Mtb APSR. Furthermore, ITC studies on representative compounds provided evidence for direct engagement of the APSR target. Finally, potent APSR inhibitors significantly decreased the cellular levels of key reduced sulfur-containing metabolites and also induced an oxidative shift in mycothiol redox potential of live Mtb, thus providing functional validation of our screening data. In summary, we have identified first-in-class inhibitors of APSR that can serve as molecular probes in unraveling the links between Mtb persistence, antibiotic tolerance, and sulfate assimilation, in addition to their potential therapeutic value.
authors.affiliation: Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States.
authors.forename: Prakash B
authors.initials: PB
authors.lastname: Palde
authors.affiliation: Department of Microbiology and Cell Biology (MCBL), Center for Infectious Disease Research (CIDR), Indian Institute of Science (IISc.) , Bangalore 560012, India.
authors.forename: Ashima
authors.initials: A
authors.lastname: Bhaskar
authors.affiliation: Lead Identification Division, The Scripps Research Institute , Jupiter, Florida 33458, United States.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Pedró Rosa
authors.affiliation: Lead Identification Division, The Scripps Research Institute , Jupiter, Florida 33458, United States.
authors.forename: Franck
authors.initials: F
authors.lastname: Madoux
authors.affiliation: Lead Identification Division, The Scripps Research Institute , Jupiter, Florida 33458, United States.
authors.forename: Peter
authors.initials: P
authors.lastname: Chase
authors.affiliation: Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States.
authors.forename: Vinayak
authors.initials: V
authors.lastname: Gupta
authors.affiliation: Lead Identification Division, The Scripps Research Institute , Jupiter, Florida 33458, United States.
authors.forename: Timothy
authors.initials: T
authors.lastname: Spicer
authors.affiliation: Lead Identification Division, The Scripps Research Institute , Jupiter, Florida 33458, United States.
authors.forename: Louis
authors.initials: L
authors.lastname: Scampavia
authors.affiliation: Department of Microbiology and Cell Biology (MCBL), Center for Infectious Disease Research (CIDR), Indian Institute of Science (IISc.) , Bangalore 560012, India.
authors.forename: Amit
authors.initials: A
authors.lastname: Singh
authors.affiliation: Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States.
authors.forename: Kate S
authors.initials: KS
authors.lastname: Carroll
mesh_terms: D000818:Animals; D000995:Antitubercular Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical; D057166:High-Throughput Screening Assays; D006801:Humans; D051379:Mice; D015394:Molecular Structure; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000037:antagonists & inhibitors* / Q000235:genetics; D015203:Reproducibility of Results; D013455:Sulfur / Q000737:chemistry / Q000378:metabolism*; D013457:Sulfur Compounds / Q000378:metabolism; D014376:Tuberculosis / Q000188:drug therapy
chemical_list: D000995:Antitubercular Agents; D013457:Sulfur Compounds; D013455:Sulfur; D050862:Oxidoreductases Acting on Sulfur Group Donors; C019618:adenylylsulfate reductase