Elucidation and chemical modulation of sulfolipid-1 biosynthesis in Mycobacterium tuberculosis
| Autor: | Julie A. Leary, Cynthia M. Holsclaw, Sarah A. Gilmore, Zsofia Botyanszki, Jessica C. Seeliger, Michael W. Schelle, Benjamin F. Cravatt, Michael Niederweis, Carolyn R. Bertozzi, Sarah E. Tully |
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| Rok vydání: | 2011 |
| Předmět: |
Sulfolipid
Virulence Factors Acylation Biological Transport Active Biology Biosynthesis Biochemistry Microbiology Mycobacterium tuberculosis 03 medical and health sciences chemistry.chemical_compound Lactones Glycolipid Bacterial Proteins Lipid biosynthesis Enzyme Inhibitors Molecular Biology Integral membrane protein 030304 developmental biology Orlistat 0303 health sciences 030306 microbiology Cell Biology Membrane transport biology.organism_classification 3. Good health Enzymes Metabolism chemistry Acyltransferase Enzymology Glycolipids Acyltransferases |
| Zdroj: | The Journal of Biological Chemistry |
| ISSN: | 1083-351X |
| Popis: | Background: Sulfolipid-1 (SL-1) is a Mycobacterium tuberculosis outer membrane lipid whose biosynthesis is not fully understood. Results: Chp1 catalyzes two acyl transfer reactions to form SL-1. Sap modulates SL-1 levels and transmembrane transport. Conclusion: The activities of Chp1 and Sap complete the SL-1 pathway. Significance: Lipid biosynthesis and transport are coupled at the membrane interface by multiple proteins that may regulate substrate specificity and flux. Mycobacterium tuberculosis possesses unique cell-surface lipids that have been implicated in virulence. One of the most abundant is sulfolipid-1 (SL-1), a tetraacyl-sulfotrehalose glycolipid. Although the early steps in SL-1 biosynthesis are known, the machinery underlying the final acylation reactions is not understood. We provide genetic and biochemical evidence for the activities of two proteins, Chp1 and Sap (corresponding to gene loci rv3822 and rv3821), that complete this pathway. The membrane-associated acyltransferase Chp1 accepts a synthetic diacyl sulfolipid and transfers an acyl group regioselectively from one donor substrate molecule to a second acceptor molecule in two successive reactions to yield a tetraacylated product. Chp1 is fully active in vitro, but in M. tuberculosis, its function is potentiated by the previously identified sulfolipid transporter MmpL8. We also show that the integral membrane protein Sap and MmpL8 are both essential for sulfolipid transport. Finally, the lipase inhibitor tetrahydrolipstatin disrupts Chp1 activity in M. tuberculosis, suggesting an avenue for perturbing SL-1 biosynthesis in vivo. These data complete the SL-1 biosynthetic pathway and corroborate a model in which lipid biosynthesis and transmembrane transport are coupled at the membrane-cytosol interface through the activity of multiple proteins, possibly as a macromolecular complex. |
| Databáze: | OpenAIRE |
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