Dihydroxy-Acid Dehydratases From Pathogenic Bacteria: Emerging Drug Targets to Combat Antibiotic Resistance |
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Authors: | Tenuun Bayaraa Jose Gaete Dr Samuel Sutiono Julia Kurz Dr Thierry Lonhienne Prof Jeffrey R Harmer Prof Paul V Bernhardt Prof Volker Sieber Prof Luke Guddat Prof Gerhard Schenk |
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Institution: | 1. School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, 4072 Australia;2. Chair of Chemistry of Biogenic resources, Campus Straubing for Biotechnology and Sustainability, Technical University of Munich, Schulgasse 16, 94315 Straubing, Germany;3. Centre for Advanced Imaging, The University of Queensland, Brisbane, 4072 Australia;4. School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, 4072 Australia
Chair of Chemistry of Biogenic resources, Campus Straubing for Biotechnology and Sustainability, Technical University of Munich, Schulgasse 16, 94315 Straubing, Germany |
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Abstract: | There is an urgent global need for the development of novel therapeutics to combat the rise of various antibiotic-resistant superbugs. Enzymes of the branched-chain amino acid (BCAA) biosynthesis pathway are an attractive target for novel anti-microbial drug development. Dihydroxy-acid dehydratase (DHAD) is the third enzyme in the BCAA biosynthesis pathway. It relies on an Fe?S cluster for catalytic activity and has recently also gained attention as a catalyst in cell-free enzyme cascades. Two types of Fe?S clusters have been identified in DHADs, i.e. 2Fe?2S] and 4Fe?4S], with the latter being more prone to degradation in the presence of oxygen. Here, we characterise two DHADs from bacterial human pathogens, Staphylococcus aureus and Campylobacter jejuni (SaDHAD and CjDHAD). Purified SaDHAD and CjDHAD are virtually inactive, but activity could be reversibly reconstituted in vitro (up to ~19,000-fold increase with kcat as high as ~6.7 s?1). Inductively-coupled plasma-optical emission spectroscopy (ICP-OES) measurements are consistent with the presence of 4Fe?4S] clusters in both enzymes. N-isopropyloxalyl hydroxamate (IpOHA) and aspterric acid are both potent inhibitors for both SaDHAD (Ki=7.8 and 51.6 μM, respectively) and CjDHAD (Ki=32.9 and 35.1 μM, respectively). These compounds thus present suitable starting points for the development of novel anti-microbial chemotherapeutics. |
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Keywords: | antibiotics dihydroxy-acid dehydratase enzyme activation Fe?S cluster sustainable chemistry |
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