Double Strike Against Tuberculosis: Beta-Lactone Inhibits Mycomembrane Biosynthesis & Enhances Effects of Antibiotics

In search of new strategies against life-threatening tuberculosis infections, a team from the Technical University of Munich (TUM), as well as Harvard University and Texas A&M University in the USA have found a new ally. They discovered a substance that interferes with the mycomembrane formation of the bacterium. It is effective even in low concentrations and when combined with known antibiotics their effectiveness is improved by up to 100-fold. Among the greatest challenges when treating life-threatening tuberculosis infections is the increasing resistance to antibiotics. But the pathogen itself also makes the life of doctors difficult: its dense mycomembrane hampers the effect of many medications. A team of scientists headed by Stephan A. Sieber, Professor of Organic Chemistry at TU Munich, has discovered a substance that perturbs the formation of this membrane significantly. The mycomembrane of the tuberculosis pathogen Mycobacterium tuberculosis consists of a lipid double layer that encapsulates the cell wall, forming an exterior barrier. Structural hallmarks are mycolic acids, branched beta-hydroxy fatty acids with two long hydrocarbon chains. The team hypothesized that similarly structured beta lactones could "mask" themselves as mycolic acid to enter the mycolic acid metabolic pathways and then block the decisive enzymes. In the context of an extensive search, the interdisciplinary team of scientists hit the bullseye with the beta lactone EZ120. It does indeed inhibit the biosynthesis of the mycomembrane and kills mycobacteria effectively. Using enzyme assays and mass spectroscopy investigations, Dr.
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