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ABSTRACT: The writing's on the (cell) wall: A series of Lipid II analogues with modifications to the peptide moiety were evaluated as substrates of bacterial transglycosylase. The first two positions on the peptide, D-lactate and L-alanine, especially their methyl groups, were found to be essential for substrate-binding activity, an important discovery for the design of antibiotics to inhibit cell-wall biosynthesis.
Angewandte Chemie International Edition 09/2012; 51(40):10123-6. · 13.45 Impact Factor
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ABSTRACT: Bacterial transpeptidase and transglycosylase on the surface are essential for cell wall synthesis, and many antibiotics have been developed to target the transpeptidase; however, the problem of antibiotic resistance has arisen and caused a major threat in bacterial infection. The transglycosylase has been considered to be another excellent target, but no antibiotics have been developed to target this enzyme. Here, we determined the crystal structure of the Staphylococcus aureus membrane-bound transglycosylase, monofunctional glycosyltransferase, in complex with a lipid II analog to 2.3 Å resolution. Our results showed that the lipid II-contacting residues are not only conserved in WT and drug-resistant bacteria but also significant in enzymatic activity. Mechanistically, we proposed that K140 and R148 in the donor site, instead of the previously proposed E156, are used to stabilize the pyrophosphate-leaving group of lipid II, and E100 in the acceptor site acts as general base for the 4-OH of GlcNAc to facilitate the transglycosylation reaction. This mechanism, further supported by mutagenesis study and the structure of monofunctional glycosyltransferase in complex with moenomycin in the donor site, provides a direction for antibacterial drugs design.
Proceedings of the National Academy of Sciences 04/2012; 109(17):6496-501. · 9.68 Impact Factor
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ABSTRACT: A feasible synthetic approach toward the Mycobacterium tuberculosis (Mtb) N-glycolyl lipid II-like molecule 1 is described. Compound 1 bears pendant undecaprenol and l-lysin moieties instead of the naturally occurring decaprenol and meso-diaminopimelic acid, which are not readily available. Functionalization of 1 with a fluorophore on the peptide side chain gave 14, which was found to be recognized as an Mtb TGase substrate. This result suggests it has tremendous utility for mechanistic studies, the characterization of mycobacterial enzymes, and mycobacterial TGase inhibitor evaluation.
Organic Letters 09/2011; 13(19):5306-9. · 5.86 Impact Factor
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ABSTRACT: A new synthetic approach toward the bacterial transglycosylase substrates, Lipid II (1) and Lipid IV (2), is described. The key disaccharide was synthesized using the concept of relative reactivity value (RRV) and elaborated to Lipid II and Lipid IV by conjugation with the appropriate oligopeptides and pyrophosphate lipids. Interestingly, the results from our HPLC-based functional TGase assay suggested Lipid IV has a higher affinity for the enzyme than Lipid II.
Organic Letters 07/2011; 13(17):4600-3. · 5.86 Impact Factor
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Ting-Jen Rachel Cheng,
Ying-Ta Wu,
Shih-Ting Yang,
Kien-Hock Lo,
Shao-Kang Chen,
Yin-Hsuan Chen,
Wen-I Huang,
Chih-Hung Yuan,
Chih-Wei Guo,
Lin-Ya Huang,
Kuo-Ting Chen, Hao-Wei Shih,
Yih-Shyun E Cheng,
Wei-Chieh Cheng,
Chi-Huey Wong
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ABSTRACT: To identify new transglycosylase inhibitors with potent anti-methicillin-resistant Staphylococcus aureus (MRSA) activities, a high-throughput screening against Staphylococcus aureus was conducted to look for antibacterial cores in our 2M compound library that consists of natural products, proprietary collection, and synthetic molecules. About 3600 hits were identified from the primary screening and the subsequent confirmation resulted in a total of 252 compounds in 84 clusters which showed anti-MRSA activities with MIC values as low as 0.1 μg/ml. Subsequent screening targeting bacterial transglycosylase identified a salicylanilide-based core that inhibited the lipid II polymerization and the moenomycin-binding activities of transglycosylase. Among the collected analogues, potent inhibitors with the IC(50) values below 10 μM against transglycosylase were identified. The non-carbonhydrate scaffold reported in this study suggests a new direction for development of bacterial transglycosylase inhibitors.
Bioorganic & medicinal chemistry 10/2010; 18(24):8512-29. · 2.82 Impact Factor
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ABSTRACT: The development of iminocyclitol-based small molecule libraries against a bacterial TGase is described. An iminocyclitol was conjugated with a pyrophosphate mimic using either a 1,3-dipolar cycloaddition or reductive amination reaction, which was then condensed with a variety of lipophilic carboxylic acids in an amide bond coupling to generate a desired molecular library. With assistance of microtiter plate-based combinatorial chemistry and in situ screening, a potential inhibitor, the first potent iminocyclitol-based inhibitor against bacterial TGases was efficiently developed.
Organic & Biomolecular Chemistry 06/2010; 8(11):2586-93. · 3.70 Impact Factor
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Chen-Yu Liu,
Chih-Wei Guo,
Yi-Fan Chang,
Jen-Tsung Wang, Hao-Wei Shih,
Yu-Fang Hsu,
Chia-Wei Chen,
Shao-Kang Chen,
Yen-Chih Wang,
Ting-Jen R Cheng,
Che Ma,
Chi-Huey Wong,
Jim-Min Fang,
Wei-Chieh Cheng
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ABSTRACT: The preparation of a novel fluorescent lipid II-based substrate for transglycosylases (TGases) is described. This substrate has characteristic structural features including a shorter lipid chain, a fluorophore tag at the end of the lipid chain rather than on the peptide chain, and no labeling with a radioactive atom. This fluorescent substrate is readily utilized in TGase activity assays to characterize TGases and also to evaluate the activities of TGase inhibitors.
Organic Letters 02/2010; 12(7):1608-11. · 5.86 Impact Factor
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ABSTRACT: Drug-resistant bacteria have caused serious medical problems in recent years, and the need for new antibacterial agents is undisputed. Transglycosylase, a multidomain membrane protein essential for cell wall synthesis, is an excellent target for the development of new antibiotics. Here, we determined the X-ray crystal structure of the bifunctional transglycosylase penicillin-binding protein 1b (PBP1b) from Escherichia coli in complex with its inhibitor moenomycin to 2.16-A resolution. In addition to the transglycosylase and transpeptidase domains, our structure provides a complete visualization of this important antibacterial target, and reveals a domain for protein-protein interaction and a transmembrane helix domain essential for substrate binding, enzymatic activity, and membrane orientation.
Proceedings of the National Academy of Sciences 06/2009; 106(22):8824-9. · 9.68 Impact Factor
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ABSTRACT: A practical and efficient solution-phase parallel synthesis of spirooxazolinoisoxazolines has been developed. Starting from methyl serine ester, the key steps are (1) acylation with concomitant beta-elimination to form an alpha,beta-unsaturated ester, (2) 1,3-dipolar cycloaddition with an oxime to form an isoxazoline ring, (3) reduction with NaBH(4), and (4) mesylation and in situ cyclization to form an oxazoline ring. All reaction steps and workup procedures were modified to allow the use of automated equipment including a synthesizer, a multifunctional liquid handler, and a vacuum centrifuge. Using this equipment, we synthesized a 100-membered library of spirooxazolinoisoxazoline in high yield, high purity, and excellent regioselectivity.
Journal of Combinatorial Chemistry 02/2009; 11(2):281-7. · 3.41 Impact Factor
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ABSTRACT: Spectroscopic and electrochemical characterizations of ferrocene- and biferrocene-functionalized terpyridine octanethiolate monolayer-protected clusters were investigated and reported. The electrochemical measurements of Ru2+ coordinated with 4'-ferrocenyl-2,2':6',2' '-terpyridine and 4'-biferrocenyl-2,2':6',2' '-terpyridine complexes were dominated by the Ru2+/Ru3+ redox couple (E(1/2) at approximately 1.3 V), Fe(2+)/Fe(3+) redox couples (E(1/2) from approximately 0.6 to approximately 0.9 V), and terpy/terpy-/terpy2- redox couples (E(1/)(2) at ca. -1.2 and ca. -1.4 V). The substantial appreciable variations detected in the Ru2+/Ru3+ and Fe2+/Fe3+ oxidation potentials indicate that there is an interaction between the Ru2+ and Fe2+ metal centers. The coordination of the Ru2+ metal center with 4'-ferrocenyl-2,2':6',2' '-terpyridine and 4'-biferrocenyl-2,2':6',2' '-terpyridine leads to an intense 1[(d(pi)Fe)6] --> 1[d(pi)Fe)5(pi*terpyRu)1] transition in the visible region. The 1[(d(pi)Fe)6] -->1[d(pi)Fe)5(pi*terpyRu)1] transition observed at approximately 510 nm revealed that there was a qualitative electronic coupling between metal centers. The coordination of the Ru2+ transition metal center lowers the energy of the pi*terpy orbitals, causing this transition.
Langmuir 11/2004; 20(21):9340-7. · 4.19 Impact Factor
