Technische Universität München

Double strike against tuberculosis

TECHNICAL UNIVERSITY OF MUNICH

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NEWS RELEASE

Beta-lactone inhibits mycomenbrane biosynthesis and potentiates antibiotics

Double strike against tuberculosis

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 hypothesizes that similarly structured beta lactones could "mask" themselves as mycolic acid to enter the mycolic acid metabolic pathways and then block the decisive enzymes.

Helpful disrupter

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. Johannes Lehmann, a researcher at the Chair of Organic Chemistry II at TU Munich, demonstrated during his doctoral work that the new inhibitor blocks especially the enzymes Pks13 and Ag85, which play a key role in the development of mycomembranes.

EZ120 is effective even in low doses, easily passes the mycomembrane and exhibits only low toxicity to human cells. The combined application of this substance with known antibiotics showed a synergistic effect leading to significantly increased effectiveness. "Vancomycin, a common antibiotic, and EZ120 work together very well," says Prof. Sieber, who heads the Chair of Organic Chemistry II. "When used together, the dose can be reduced over 100-fold.

"The scientists suspect that disrupting the mycomembrane enables antibiotics to enter the bacteria more easily. This is a new mode of action and might be a starting point for novel tuberculosis therapies.

The research was funded by the German Research Foundation (SFB 749 and Cluster of Excellence "Center for Integrated Protein Science"), the National Institutes of Health (USA) and the German National Academic Foundation (Studienstiftung des Deutschen Volkes). Researchers from the Harvard T.H. Chan School of Public Health and Texas A & M University (College Station, USA) also participated in the research.

Publication:

Johannes Lehmann, Tan-Yun Cheng, Anup Aggarwal, Annie S. Park, Evelyn Zeiler, Ravikiran M. Raju, Tatos Akopian, Olga Kandror, James C. Sacchettini, D. Branch Moody, Eric J. Rubin und Stephan A. Sieber: An Antibacterial ß-Lactone Kills Mycobacterium tuberculosis by Disrupting Mycolic Acid Biosynthesis, Angew. Chem Int Ed Engl. 2017. DOI: 10.1002/anie.201709365

Contact:

Prof. Dr. Stephan A. Sieber

Technical University of Munich

Chair of Organic Chemistry II

Phone: +49 89 289 13302

Mail: stephan.sieber@tum.de

The Technical University of Munich (TUM) is one of Europe's leading research
universities, with more than 550 professors, 41,000 students, and 10,000
academic and non-academic staff. Its focus areas are the engineering sciences,
natural sciences, life sciences and medicine, combined with economic and social
sciences. TUM acts as an entrepreneurial university that promotes talents and
creates value for society. In that it profits from having strong partners in
science and industry. It is represented worldwide with the TUM Asia campus in
Singapore as well as offices in Beijing, Brussels, Cairo, Mumbai, San Francisco,
and São Paulo. Nobel Prize winners and inventors such as Rudolf Diesel, Carl von
Linde, and Rudolf Mößbauer have done research at TUM. In 2006 and 2012 it won
recognition as a German "Excellence University." In international 
rankings, TUM
regularly places among the best universities in Germany. 



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