Type II Fatty Acid Synthesis Is Essential for the Replication of Chlamydia trachomatis |
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Authors: | Jiangwei Yao Yasser M. Abdelrahman Rosanna M. Robertson John V. Cox Robert J. Belland Stephen W. White Charles O. Rock |
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Affiliation: | From the Departments of ‡Infectious Diseases and ;‖Structural Biology, St. Jude Children''s Research Hospital, Memphis, Tennessee 48105.;the §Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Science Center, Memphis, Tennessee 38163, and ;the ¶Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt |
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Abstract: | 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. |
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Keywords: | Bacterial Metabolism Chlamydia trachomatis Enzyme Inhibitor Fatty Acid Synthase (FAS) Glycerophospholipid Fatty Acid Synthesis |
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