The Fatty Acid Synthesis Protein Enoyl-ACP Reductase II (FabK) is a Target for Narrow-Spectrum Antibacterials for Clostridium difficile Infection

ACS Infect Dis. 2019 Feb 8;5(2):208-217. doi: 10.1021/acsinfecdis.8b00205. Epub 2018 Dec 13.

Abstract

Clostridium difficile infection (CDI) is an antibiotic-induced microbiota shift disease of the large bowel. While there is a need for narrow-spectrum CDI antibiotics, it is unclear which cellular proteins are appropriate drug targets to specifically inhibit C. difficile. We evaluated the enoyl-acyl carrier protein (ACP) reductase II (FabK), which catalyzes the final step of bacterial fatty acid biosynthesis. Bioinformatics showed that C. difficile uses FabK as its sole enoyl-ACP reductase, unlike several major microbiota species. The essentiality of fabK for C. difficile growth was confirmed by failure to delete this gene using ClosTron mutagenesis and by growth inhibition upon gene silencing with CRISPR interference antisense to fabK transcription or by blocking protein translation. Inhibition of C. difficile's FASII pathway could not be circumvented by supply of exogenous fatty acids, either during fabK's gene silencing or upon inhibition of the enzyme with a phenylimidazole-derived inhibitor (1). The inability of fatty acids to bypass FASII inhibition is likely due to the function of the transcriptional repressor FapR. Inhibition of FabK also inhibited spore formation, reflecting the enzyme's role in de novo fatty acid biosynthesis for the formation of spore membrane lipids. Compound 1 did not inhibit growth of key microbiota species. These findings suggest that C. difficile FabK is a druggable target for discovering narrow-spectrum anti- C. difficile drugs that treat CDI but avoid collateral damage to the gut microbiota.

Keywords: CRISPR interference antisense; Clostridium difficile; enoyl-ACP reductase; narrow-spectrum drug target; phenylimidazole-derived inhibitor.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Biosynthetic Pathways
  • CRISPR-Cas Systems
  • Clostridioides difficile / drug effects*
  • Clostridioides difficile / enzymology
  • Clostridioides difficile / genetics
  • Crystallography, X-Ray
  • DNA, Antisense
  • Enoyl-(Acyl-Carrier-Protein) Reductase (NADH) / antagonists & inhibitors*
  • Enoyl-(Acyl-Carrier-Protein) Reductase (NADH) / genetics
  • Fatty Acids / biosynthesis
  • Gene Silencing

Substances

  • Anti-Bacterial Agents
  • DNA, Antisense
  • Fatty Acids
  • Enoyl-(Acyl-Carrier-Protein) Reductase (NADH)