Abstract
Antibiotics that use novel mechanisms are needed to combat antimicrobial resistance
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. Teixobactin
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represents a new class of antibiotics with a unique chemical scaffold and lack of ...detectable resistance. Teixobactin targets lipid II, a precursor of peptidoglycan
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. Here we unravel the mechanism of teixobactin at the atomic level using a combination of solid-state NMR, microscopy, in vivo assays and molecular dynamics simulations. The unique enduracididine C-terminal headgroup of teixobactin specifically binds to the pyrophosphate-sugar moiety of lipid II, whereas the N terminus coordinates the pyrophosphate of another lipid II molecule. This configuration favours the formation of a β-sheet of teixobactins bound to the target, creating a supramolecular fibrillar structure. Specific binding to the conserved pyrophosphate-sugar moiety accounts for the lack of resistance to teixobactin
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. The supramolecular structure compromises membrane integrity. Atomic force microscopy and molecular dynamics simulations show that the supramolecular structure displaces phospholipids, thinning the membrane. The long hydrophobic tails of lipid II concentrated within the supramolecular structure apparently contribute to membrane disruption. Teixobactin hijacks lipid II to help destroy the membrane. Known membrane-acting antibiotics also damage human cells, producing undesirable side effects. Teixobactin damages only membranes that contain lipid II, which is absent in eukaryotes, elegantly resolving the toxicity problem. The two-pronged action against cell wall synthesis and cytoplasmic membrane produces a highly effective compound targeting the bacterial cell envelope. Structural knowledge of the mechanism of teixobactin will enable the rational design of improved drug candidates.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Antimicrobial resistance is a leading mortality factor worldwide. Here, we report the discovery of clovibactin, an antibiotic isolated from uncultured soil bacteria. Clovibactin efficiently kills ...drug-resistant Gram-positive bacterial pathogens without detectable resistance. Using biochemical assays, solid-state nuclear magnetic resonance, and atomic force microscopy, we dissect its mode of action. Clovibactin blocks cell wall synthesis by targeting pyrophosphate of multiple essential peptidoglycan precursors (C55PP, lipid II, and lipid IIIWTA). Clovibactin uses an unusual hydrophobic interface to tightly wrap around pyrophosphate but bypasses the variable structural elements of precursors, accounting for the lack of resistance. Selective and efficient target binding is achieved by the sequestration of precursors into supramolecular fibrils that only form on bacterial membranes that contain lipid-anchored pyrophosphate groups. This potent antibiotic holds the promise of enabling the design of improved therapeutics that kill bacterial pathogens without resistance development.
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•Clovibactin was discovered in a previously uncultivated bacterium•Kills without resistance and is efficacious in a mouse model of S. aureus infection•It blocks the cell wall biosynthesis by targeting distinct, essential precursors•Clovibactin uses an unusual hydrophobic interface to target immutable pyrophosphate
Clovibactin, a new antibiotic isolated from soil bacteria, blocks bacterial cell wall synthesis by targeting essential peptidoglycan precursors, allowing it to kill drug-resistant bacterial pathogens without detectable resistance.
Specific interactions with phospholipids are often critical for the function of proteins or drugs, but studying these interactions at high resolution remains difficult, especially in complex ...membranes that mimic biological conditions. In principle, molecular interactions with phospholipids could be directly probed by solid‐state NMR (ssNMR). However, due to the challenge to detect specific lipids in mixed liposomes and limited spectral sensitivity, ssNMR studies of specific lipids in complex membranes are scarce. Here, by using purified biological 13C,15N‐labeled phospholipids, we show that we can selectively detect traces of specific lipids in complex membranes. In combination with 1H‐detected ssNMR, we show that our approach provides unprecedented high‐resolution insights into the mechanisms of drugs that target specific lipids. This broadly applicable approach opens new opportunities for the molecular characterization of specific lipid interactions with proteins or drugs in complex fluid membranes.
Specific lipid interaction in complex membranes: Specific interactions with lipids are critical for proteins and drugs, however, direct structural measurements of interactions with lipids remain difficult, especially in membranes that mimic biological conditions. Here, a broadly applicable solid‐state NMR approach is presented that enables to directly measure specific interactions with lipids such as cardiolipin in complex fluid membranes.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
This work investigates the addition of monosaccharides to marketed drugs to improve their pharmacokinetic properties for oral absorption. To this end, a set of chloromethyl glycoside synthons were ...developed to prepare a variety of glycosyloxymethyl‐prodrugs derived from 5‐fluorouracil, thioguanine, propofol and losartan. Drug release was studied in vitro using β‐glucosidase confirming rapid conversion of the monosaccharide prodrugs to release the parent drug, formaldehyde and the monosaccharide. To showcase this prodrug approach, a glucosyloxymethyl conjugate of the tetrazole‐containing drug losartan was used for in vivo experiments and showed complete release of the drug in a dog‐model.
Monosaccharides were introduced on drug molecules to improve their solubility, metabolic stability and oral bioavailability. A new chloromethyl glycoside synthon was developed to enable the synthesis of numerous monosaccharide prodrugs.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract The marine environment, contains plentiful renewable resources, e.g. macroalgae with unique polysaccharides, motivating search for enzymes from marine microorganisms to explore conversion ...possibilities of the polysaccharides. In this study, the first GH17 glucanosyltransglycosylase, MlGH17B, from a marine bacterium (Muricauda lutaonensis), was characterized. The enzyme was moderately thermostable with Tm at 64.4 °C and 73.2 °C, but an activity optimum at 20 °C, indicating temperature sensitive active site interactions. MlGH17B uses β-1,3 laminari-oligosaccharides with a degree of polymerization (DP) of 4 or higher as donors. Two glucose moieties (bound in the aglycone +1 and +2 subsites) are cleaved off from the reducing end of the donor while the remaining part (bound in the glycone subsites) is transferred to an incoming β-1,3 glucan acceptor, making a β-1,6-linkage, thereby synthesizing branched or kinked oligosaccharides. Synthesized oligosaccharides up to DP26 were detected by mass spectrometry analysis, showing that repeated transfer reactions occurred, resulting in several β-1,6-linked branches. The modeled structure revealed an active site comprising five subsites: three glycone (−3, −2 and −1) and two aglycone (+1 and +2) subsites, with significant conservation of substrate interactions compared to the only crystallized 1,3-β-glucanosyltransferase from GH17 (RmBgt17A from the compost thriving fungus Rhizomucor miehei), suggesting a common catalytic mechanism, despite different phylogenetic origin, growth environment, and natural substrate. Both enzymes lacked the subdomain extending the aglycone subsites, found in GH17 endo-β-glucanases from plants, but this extension was also missing in bacterial endoglucanases (modeled here), showing that this feature does not distinguish transglycosylation from hydrolysis, but may rather relate to phylogeny.
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