Type II Fatty Acid Synthesis Is Essential for the Replication of Chlamydia trachomatis

• Published in: The Journal of biological chemistry 2014-08, Vol.289 (32), p.22365-22376
• Main Authors: Yao, Jiangwei, Abdelrahman, Yasser M., Robertson, Rosanna M., Cox, John V., Belland, Robert J., White, Stephen W., Rock, Charles O.
• Format: Article
• Language: English
• Subjects: 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; Lipids; Models, Molecular; Molecular Sequence Data; Protein Structure, Quaternary; Pyrones - pharmacology; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M114.584185

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.