title: Discovery and characterization of a novel class of pyrazolopyrimidinedione tRNA synthesis inhibitors.
abstract: A high-throughput phenotypic screen for novel antibacterial agents led to the discovery of a novel pyrazolopyrimidinedione, PPD-1, with preferential activity against methicillin-resistant Staphylococcus aureus (MRSA). Resistance mapping revealed the likely target of inhibition to be lysyl tRNA synthetase (LysRS). Preliminary structure-activity relationship (SAR) studies led to an analog, PPD-2, which gained Gram-negative antibacterial activity at the expense of MRSA activity and resistance to this compound mapped to prolyl tRNA synthetase (ProRS). These targets of inhibition were confirmed in vitro, with PPD-1 showing IC₅₀s of 21.7 and 35 μM in purified LysRS and ProRS enzyme assays, and PPD-2, 151 and 0.04 μM, respectively. The highly attractive chemical properties of these compounds combined with intriguing preliminary SAR suggest that further exploration of this compelling novel series is warranted.
authors.affiliation: Department of Medicinal Chemistry, Antibacterials Research Unit, Pfizer Worldwide Research and Development, Groton, CT, USA.
authors.forename: Justin I
authors.initials: JI
authors.lastname: Montgomery
authors.affiliation: Department of Discovery Biology, Antibacterials Research Unit, Pfizer Worldwide Research and Development, Groton, CT, USA.
authors.forename: James F
authors.initials: JF
authors.lastname: Smith
authors.affiliation: Department of Discovery Biology, Antibacterials Research Unit, Pfizer Worldwide Research and Development, Groton, CT, USA.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Tomaras
authors.affiliation: Department of Discovery Biology, Antibacterials Research Unit, Pfizer Worldwide Research and Development, Groton, CT, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Zaniewski
authors.affiliation: Department of Discovery Biology, Antibacterials Research Unit, Pfizer Worldwide Research and Development, Groton, CT, USA.
authors.forename: Craig J
authors.initials: CJ
authors.lastname: McPherson
authors.affiliation: Department of Medicinal Chemistry, Antibacterials Research Unit, Pfizer Worldwide Research and Development, Groton, CT, USA.
authors.forename: Laura A
authors.initials: LA
authors.lastname: McAllister
authors.affiliation: Department of Discovery Biology, Antibacterials Research Unit, Pfizer Worldwide Research and Development, Groton, CT, USA.
authors.forename: Sandra
authors.initials: S
authors.lastname: Hartman-Neumann
authors.affiliation: Department of Medicinal Chemistry, Antibacterials Research Unit, Pfizer Worldwide Research and Development, Groton, CT, USA.
authors.forename: Joel T
authors.initials: JT
authors.lastname: Arcari
authors.affiliation: Department of Discovery Biology, Antibacterials Research Unit, Pfizer Worldwide Research and Development, Groton, CT, USA.
authors.forename: Marykay
authors.initials: M
authors.lastname: Lescoe
authors.affiliation: Department of Discovery Biology, Antibacterials Research Unit, Pfizer Worldwide Research and Development, Groton, CT, USA.
authors.forename: Jemy
authors.initials: J
authors.lastname: Gutierrez
authors.affiliation: Department of Discovery Biology, Antibacterials Research Unit, Pfizer Worldwide Research and Development, Groton, CT, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Department of Medicinal Chemistry, Antibacterials Research Unit, Pfizer Worldwide Research and Development, Groton, CT, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Limberakis
authors.affiliation: Department of Discovery Biology, Antibacterials Research Unit, Pfizer Worldwide Research and Development, Groton, CT, USA.
authors.forename: Alita A
authors.initials: AA
authors.lastname: Miller
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015195:Drug Design; D055808:Drug Discovery; D024881:Drug Resistance, Bacterial; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D029968:Escherichia coli Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D057166:High-Throughput Screening Assays; D008250:Lysine-tRNA Ligase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D016106:Methicillin Resistance; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D008826:Microbial Sensitivity Tests; D009344:Neisseria gonorrhoeae / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D011720:Pyrazoles / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D011744:Pyrimidinones / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D046249:Transfer RNA Aminoacylation / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D029968:Escherichia coli Proteins; D011720:Pyrazoles; D011744:Pyrimidinones; D011994:Recombinant Proteins; D000604:Amino Acyl-tRNA Synthetases; C100134:prolyl T RNA synthetase; D008250:Lysine-tRNA Ligase