AFN-1252 is a potent inhibitor of enoyl-ACP reductase from Burkholderia pseudomallei--Crystal structure, mode of action, and biological activity

Protein Sci. 2015 May;24(5):832-40. doi: 10.1002/pro.2655. Epub 2015 Apr 2.

Abstract

Melioidosis is a tropical bacterial infection caused by Burkholderia pseudomallei (B. pseudomallei; Bpm), a Gram-negative bacterium. Current therapeutic options are largely limited to trimethoprim-sulfamethoxazole and β-lactam drugs, and the treatment duration is about 4 months. Moreover, resistance has been reported to these drugs. Hence, there is a pressing need to develop new antibiotics for Melioidosis. Inhibition of enoyl-ACP reducatase (FabI), a key enzyme in the fatty acid biosynthesis pathway has shown significant promise for antibacterial drug development. FabI has been identified as the major enoyl-ACP reductase present in B. pseudomallei. In this study, we evaluated AFN-1252, a Staphylococcus aureus FabI inhibitor currently in clinical development, for its potential to bind to BpmFabI enzyme and inhibit B. pseudomallei bacterial growth. AFN-1252 stabilized BpmFabI and inhibited the enzyme activity with an IC50 of 9.6 nM. It showed good antibacterial activity against B. pseudomallei R15 strain, isolated from a melioidosis patient (MIC of 2.35 mg/L). X-ray structure of BpmFabI with AFN-1252 was determined at a resolution of 2.3 Å. Complex of BpmFabI with AFN-1252 formed a symmetrical tetrameric structure with one molecule of AFN-1252 bound to each monomeric subunit. The kinetic and thermal melting studies supported the finding that AFN-1252 can bind to BpmFabI independent of cofactor. The structural and mechanistic insights from these studies might help the rational design and development of new FabI inhibitors.

Keywords: AFN-1252; Burkholderia pseudomallei; FabI; Melioidosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / therapeutic use
  • Benzofurans / chemistry*
  • Benzofurans / therapeutic use
  • Burkholderia pseudomallei / drug effects
  • Burkholderia pseudomallei / enzymology*
  • Crystallography, X-Ray
  • Enoyl-(Acyl-Carrier-Protein) Reductase (NADH) / antagonists & inhibitors
  • Enoyl-(Acyl-Carrier-Protein) Reductase (NADH) / chemistry*
  • Enoyl-(Acyl-Carrier-Protein) Reductase (NADH) / metabolism
  • Humans
  • Kinetics
  • Melioidosis / drug therapy
  • Melioidosis / enzymology*
  • Melioidosis / microbiology
  • Pyrones / chemistry*
  • Pyrones / therapeutic use
  • Staphylococcal Infections / drug therapy
  • Staphylococcal Infections / microbiology

Substances

  • API 1252
  • Anti-Bacterial Agents
  • Benzofurans
  • Pyrones
  • Enoyl-(Acyl-Carrier-Protein) Reductase (NADH)