Discovery of inhibitors of 4'-phosphopantetheine adenylyltransferase (PPAT) to validate PPAT as a target for antibacterial therapy

Antimicrob Agents Chemother. 2013 Dec;57(12):6005-15. doi: 10.1128/AAC.01661-13. Epub 2013 Sep 16.

Abstract

Inhibitors of 4'-phosphopantetheine adenylyltransferase (PPAT) were identified through high-throughput screening of the AstraZeneca compound library. One series, cycloalkyl pyrimidines, showed inhibition of PPAT isozymes from several species, with the most potent inhibition of enzymes from Gram-positive species. Mode-of-inhibition studies with Streptococcus pneumoniae and Staphylococcus aureus PPAT demonstrated representatives of this series to be reversible inhibitors competitive with phosphopantetheine and uncompetitive with ATP, binding to the enzyme-ATP complex. The potency of this series was optimized using structure-based design, and inhibition of cell growth of Gram-positive species was achieved. Mode-of-action studies, using generation of resistant mutants with targeted sequencing as well as constructs that overexpress PPAT, demonstrated that growth suppression was due to inhibition of PPAT. An effect on bacterial burden was demonstrated in mouse lung and thigh infection models, but further optimization of dosing requirements and compound properties is needed before these compounds can be considered for progress into clinical development. These studies validated PPAT as a novel target for antibacterial therapy.

MeSH terms

  • Animals
  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Proteins / antagonists & inhibitors*
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism
  • Binding, Competitive
  • Crystallography, X-Ray
  • Drug Discovery
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacology*
  • Female
  • Lung / drug effects
  • Lung / microbiology
  • Mice
  • Models, Molecular
  • Nucleotidyltransferases / antagonists & inhibitors*
  • Nucleotidyltransferases / chemistry
  • Nucleotidyltransferases / metabolism
  • Pantetheine / analogs & derivatives
  • Pantetheine / chemistry
  • Pneumococcal Infections / drug therapy
  • Pneumococcal Infections / microbiology
  • Pneumonia, Bacterial / drug therapy
  • Pneumonia, Bacterial / microbiology
  • Small Molecule Libraries / chemistry
  • Small Molecule Libraries / pharmacology*
  • Staphylococcus aureus / drug effects*
  • Staphylococcus aureus / enzymology
  • Staphylococcus aureus / growth & development
  • Streptococcus pneumoniae / drug effects*
  • Streptococcus pneumoniae / enzymology
  • Streptococcus pneumoniae / growth & development
  • Thigh / microbiology

Substances

  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Enzyme Inhibitors
  • Small Molecule Libraries
  • Pantetheine
  • Nucleotidyltransferases
  • pantetheine-phosphate adenylyltransferase
  • 4'-phosphopantetheine