Type II fatty acid synthesis is essential for the replication of Chlamydia trachomatis

J Biol Chem. 2014 Aug 8;289(32):22365-76. doi: 10.1074/jbc.M114.584185. Epub 2014 Jun 23.


The major phospholipid classes of the obligate intracellular bacterial parasite Chlamydia trachomatis are the same as its eukaryotic host except that they also contain chlamydia-made branched-chain fatty acids in the 2-position. Genomic analysis predicts that C. trachomatis is capable of type II fatty acid synthesis (FASII). AFN-1252 was deployed as a chemical tool to specifically inhibit the enoyl-acyl carrier protein reductase (FabI) of C. trachomatis to determine whether chlamydial FASII is essential for replication within the host. The C. trachomatis FabI (CtFabI) is a homotetramer and exhibited typical FabI kinetics, and its expression complemented an Escherichia coli fabI(Ts) strain. AFN-1252 inhibited CtFabI by binding to the FabI·NADH complex with an IC50 of 0.9 μM at saturating substrate concentration. The x-ray crystal structure of the CtFabI·NADH·AFN-1252 ternary complex revealed the specific interactions between the drug, protein, and cofactor within the substrate binding site. AFN-1252 treatment of C. trachomatis-infected HeLa cells at any point in the infectious cycle caused a decrease in infectious titers that correlated with a decrease in branched-chain fatty acid biosynthesis. AFN-1252 treatment at the time of infection prevented the first cell division of C. trachomatis, although the cell morphology suggested differentiation into a metabolically active reticulate body. These results demonstrate that FASII activity is essential for C. trachomatis proliferation within its eukaryotic host and validate CtFabI as a therapeutic target against C. trachomatis.

Keywords: Bacterial Metabolism; Chlamydia trachomatis; Enzyme Inhibitor; Fatty Acid Synthase (FAS); Fatty Acid Synthesis; Glycerophospholipid.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / antagonists & inhibitors
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Benzofurans / pharmacology
  • Cell Proliferation / drug effects
  • Chlamydia trachomatis / genetics
  • Chlamydia trachomatis / metabolism*
  • Chlamydia trachomatis / pathogenicity
  • Crystallography, X-Ray
  • Enoyl-(Acyl-Carrier-Protein) Reductase (NADH) / antagonists & inhibitors
  • Enoyl-(Acyl-Carrier-Protein) Reductase (NADH) / genetics
  • Enoyl-(Acyl-Carrier-Protein) Reductase (NADH) / metabolism
  • Enzyme Inhibitors / pharmacology
  • Fatty Acid Synthase, Type II / antagonists & inhibitors
  • Fatty Acid Synthase, Type II / genetics
  • Fatty Acid Synthase, Type II / metabolism
  • Fatty Acids / biosynthesis*
  • Genes, Bacterial
  • HeLa Cells
  • Humans
  • Kinetics
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Structure, Quaternary
  • Pyrones / pharmacology
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism


  • API 1252
  • Bacterial Proteins
  • Benzofurans
  • Enzyme Inhibitors
  • Fatty Acids
  • Pyrones
  • Recombinant Proteins
  • Enoyl-(Acyl-Carrier-Protein) Reductase (NADH)
  • Fatty Acid Synthase, Type II

Associated data

  • PDB/4Q9N