个人简介

Bristol, 1974, BSc Bristol (ML Sinnott), 1997, PhD Alberta (N.B. Madsen and B.D. Sykes), 1978, Postdoctoral

研究领域

Our interests focus primarily upon enzymes that catalyse glycoside formation and hydrolysis, since these play crucial roles in all areas of biology. Applications of our research (see below) range from the development of new catalysts for industrial processes to the design, synthesis and testing of new therapeutics. Understanding: Mechanistic studies are the foundation of our program and range from the discovery and analysis of “new” mechanisms by which enzymes catalyse these reactions through to development of a deeper understanding of how the enzymes for which we know the fundamental mechanisms achieve such enormous (107 fold) rate accelerations. The approaches adopted involve a combination of synthetic organic chemistry (synthesis of substrate analogues, inhibitors, etc.), molecular biology (cloning, mutagenesis, etc.,) and biochemistry (enzyme purification, kinetics, labeling, peptide mapping). These are often coupled with collaborative crystallographic and NMR studies of protein/ligand complexes to gain insights into structures, dynamics and electrostatics of the species along the enzyme’s reaction coordinates. We also utilise mass spectrometry for peptide mapping and gas phase studies. Central to our mechanistic studies are the databases CAZY and CAZYPEDIA. Inhibitors of glycosidases have value both as mechanistic probes and as potential diagnostics and therapeutics. Mechanism-based covalent inhibitors, often based upon fluorosugars, have been designed and used by our lab to prove covalent catalysis, to identify active site residues andto visualize structures of reaction intermediates. These, along with non-covalent inhibitors, are being developed as potential therapeutics in conjunction with B.C.’s Centre for Drug Research and Development (CDRD). Trials are currently underway for new treatments for influenza (neuraminidase inhibition), diabetes (α-amylase inhibition) and lysosomal storage diseases (pharmacological chaperones). These candidates were derived both by design / synthesis and by high-throughput screening of natural product extracts. Engineering: a particular challenge in glycoscience is the efficient assembly of oligosaccharides and glycoproteins – especially on the large scale. We have generated glycosynthases and glycoligases (engineered glycosidases) for the high-yielding assembly of glycosides. Through application of directed evolution approaches that mimic the process of natural selection, but in the laboratory, we are generating improved versions of these enzymes with activities up to 5000 times higher than their parents. Our involvement in the Centre for High-Throughput Biology (CHiBi) is central to such studies. Students interested in genome-wide and high-throughput chemical biology studies are also alerted to our new Genome Sciences and Technology (GSAT) graduate program.

Our interests focus primarily upon enzymes that catalyse glycoside formation and hydrolysis, since these play crucial roles in all areas of biology. Applications of our research (see below) range from the development of new catalysts for industrial processes to the design, synthesis and testing of new therapeutics. Understanding: Mechanistic studies are the foundation of our program and range from the discovery and analysis of "new" mechanisms by which enzymes catalyse these reactions through to development of a deeper understanding of how the enzymes for which we know the fundamental mechanisms achieve such enormous (107 fold) rate accelerations. The approaches adopted involve a combination of synthetic organic chemistry (synthesis of substrate analogues, inhibitors, etc.), molecular biology (cloning, mutagenesis, etc.,) and biochemistry (enzyme purification, kinetics, labeling, peptide mapping). These are often coupled with collaborative crystallographic and NMR studies of protein/ligand complexes to gain insights into structures, dynamics and electrostatics of the species along the enzyme’s reaction coordinates. We also utilise mass spectrometry for peptide mapping and gas phase studies. Central to our mechanistic studies are the databases CAZY and CAZYPEDIA. Inhibitors of glycosidases have value both as mechanistic probes and as potential diagnostics and therapeutics. Mechanism-based covalent inhibitors, often based upon fluorosugars, have been designed and used by our lab to prove covalent catalysis, to identify active site residues andto visualize structures of reaction intermediates. These, along with non-covalent inhibitors, are being developed as potential therapeutics in conjunction with B.C.’s Centre for Drug Research and Development (CDRD). Trials are currently underway for new treatments for influenza (neuraminidase inhibition), diabetes (α-amylase inhibition) and lysosomal storage diseases (pharmacological chaperones). These candidates were derived both by design / synthesis and by high-throughput screening of natural product extracts. Engineering: a particular challenge in glycoscience is the efficient assembly of oligosaccharides and glycoproteins – especially on the large scale. We have generated glycosynthases and glycoligases (engineered glycosidases) for the high-yielding assembly of glycosides. Through application of directed evolution approaches that mimic the process of natural selection, but in the laboratory, we are generating improved versions of these enzymes with activities up to 5000 times higher than their parents. Our involvement in the Centre for High-Throughput Biology (CHiBi) is central to such studies. Students interested in genome-wide and high-throughput chemical biology studies are also alerted to our new Genome Sciences and Technology (GSAT) graduate program.

近期论文

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Santana, A. G., Tysoe, C. R., Hu, G., Kronstad, J., Goddard-Borger, E., and Withers, S. G. “Fungal glycolipid hydrolase inhibitors and their effect on Cryptococcus neoformans” (2017) ChemBioChem 18, 284-290. Jongkees, S. A. K., Caner, S., Tysoe, C. R., Brayer, G. D., Withers, S. G. and Suga, H. “Rapid discovery of potent and selective glycosidase-inhibiting de novo peptides” (2017) Cell Chemical Biology. In Press. Gao, Z., Niikura, M, and Withers, S. G. “Ultrasensitive fluorogenic neuraminidase titration reagents” (2017) Angew. Chemie, In Press, accepted Jan 24 2017. Gao, Z., Niikura, M, and Withers, S. G. “Ultrasensitive fluorogenic neuraminidase titration reagents” (2017) Angew. Chemie, In Press, accepted Jan 24 2017. Schalli, M. Wolfsgruber, A., Santana, A. G., Tysoe, C. R., Fischer, R., Thonhofer, M., Withers, S. G. and Stuetz, A. “C-5a-Substituted Validamine Type Glycosidase Inhibitors” (2017) Carbohydr. Res. 440, 1-9. Strazzulli, A., Cobucci-Ponzano, B, Carillo, S., Bedini, E., Corsaro, M., M., Pocsfalvi, G., Withers, S. G., Rossi, M and Moracci, M. “Introducing transgalactosylation activity into a GH42 -galactosidase” (2017) Glycobiology In Press. Danby, P.M. and Withers, S.G. “Advances in Enzymatic Glycoside Synthesis” (2016) ACS Chemical Biology 11, 1784-1794. Morgan, J. L.; McNamara, J. T.; Fischer, M.; Rich, J.; Chen, H. M.; Withers, S. G.; Zimmer, J. Observing Cellulose Biosynthesis And Membrane Translocation In Crystallo. NATURE 2016, 531, 329–334. doi: 10.1038/nature16966 Thonhofer, M.; Santana, A. G.; Fischer, R.; Gomez, A. T.; Saf, R.; Schalli, M.; Stütz, A.E.; Withers, S. G. 5-Fluoro Derivatives Of 4-Epi-Isofagomine As D-Galactosidase Inhibitors And Potential Pharmacological Chaperones For GM1-Gangliosidosis As Well As Fabry’s Disease. CARBOHYDRATE RESEARCH 2016, 420, 6-12. doi:10.1016/j.carres.2015.10.009 Mehr, K.; Withers, S. G. Mechanisms Of The Sialidase And Trans-Sialidase Activities of Bacterial Sialyltransferases From Glycosyltransferase Family 80 (GT80). GLYCOBIOLOGY 2016, 26, 353-359. doi: 10.1093/glycob/cwv105 Kötzler, M. P.; Withers, S. G. Proteolytic Cleavage Driven By Glycosylation. JOURNAL OF BIOLOGICAL CHEMISTRY 2016, 291, 429-434. doi: 10.1074/jbc.C115.698696 Yuen, V. G.; Coleman, J.; Withers, S. G.; Andersen, R. J.; Brayer, G. D.; Mustafa, S.; McNeill, J. H. Glucose Lowering Effect Of Montbretin A In Zucker Diabetic Fatty Rats. MOLECULAR AND CELLULAR BIOCHEMISTRY 2016, 411, 473-381. doi: 10.1007/s11010-015-2599-4 McNamara, J. T.; Morgan, J. L.; W Fischer, M.; Rich, J.; Chen, H.; Withers, S. G.; Zimmer, J. Observing Cellulose Biosynthesis And Membrane Translocation In Crystallo. NATURE 2016, 529, 329-334. doi: 10.1038/nature16966 Chen, H.; Armstrong, Z.; Hallam, S.J.; Withers, S. G. Synthesis And Evaluation Of A Series Of 6-Chloro-4-Methylumbelliferyl Glycosides As Fluorogenic Reagents For Screening Metagenomic Libraries For Glycosidase Activity. CARBOHYDRATE RESEARCH 2016, 421, 33-39. doi: 10.1016/j.carres.2015.12.010 Kwan, D. H.; Jin, Y.; Jiang, J.; Chen, H.; Kötzler, M. P.; Overkleeft, H.S.; Davies, G. J.; Withers, S. G. Chemoenzymatic Synthesis Of 6-Phosphocyclophellitol As A Novel Probe Of 6-Phospho Beta-Glucosidases. FEBS LETTERS 2016, 590, 461-468. doi: 10.1002/1873-3468.12059 Thonhofer, M.; Weber, P.; Gonzalez Santana, A.; Fischer, R.; Pabst, B. M.; Paschke, E.; Schalli, M.; Stütz, A. E.; Tschernutter, M.; Windischhofer, W.; Withers, S. G. Synthesis Of C-5a-Chain Extended Derivatives Of 4-Epi-Isofagomine: Notable Beta-Galactosidase Inhibitors And Activity Promotors Of GM1-Gangliosidosis-Related Human Lysosomal Beta-Galactosidase Mutant R201C. CARBOHYDRATE RESEARCH 2016, 429, 71-80. doi 10.1016/j.carres.2016.03.020 Tysoe, C.T.; Williams, L.K.; Keyzers, R.; Nguyen, N.; Tarling, C.; Wicki, J.; Goddard-Borger, E.D.; Aguda, A.; Perry, S.; Foster, L.J.; Andersen, R.J.; Brayer, G.D.; Withers, S. G. Potent Human Alpha-Amylase Inhibition By The Beta-Defensin-Like Protein Helianthamide. ACS CENTRAL SCIENCE 2016, 2, 154-161. doi: 10.1021/acscentsci.5b00399 Caner, S.; Zhang, X.; Jiang, J.; Chen, H.; Nguyen, N. T.; Overkleeft, O.; Brayer, G.D.; Withers, S. G. Glucosyl Epi-cyclophellitol Allows Mechanism-Based Inactivation And Structural Analysis of Human Pancreatic Alpha-Amylase. FEBS LETTERS 2016, 590, 1143-1151. doi: 10.1002/1873-3468.12143 Santana, A.G.; Vadlamani, G.; Mark, B. L.; Withers, S. G. N-Acetyl Glycals Are Tight-Binding And Environmentally Insensitive Inhibitors Of Hexosaminidases. CHEMICAL COMMUNICATIONS 2016, 52, 7943-7946. doi: 10.1039/C6CC02520J Zoidl, M.; Gonzalez Santana, A.; Torvisco, A.; Tysoe, C.T.; Siriwardena, A.; Withers, S. G.; Wrodnigg, T. M . The Staudinger/aza-Wittig Reaction As Key Step For The Concise Synthesis of 1-C-Alkyl-Iminoalditol Glycomimetics. CARBOHYDRATE RESEARCH 2016, 429, 62-70. doi: 10.1016/j.carres.2016.04.006 Danby, P.M.; Withers, S.G. Advances in Enzymatic Glycoside Synthesis. ACS CHEMICAL BIOLOGY 2016, 11, 1784-1794. doi: 10.1021/acschembio.6b00340 Ma, F.; Fischer, M.; Han, Y.; Withers, S.G.; Feng, Y.; Yang, G. Substrate Engineering Enabling Fluorescence Droplet Entrapment For IVC-FACS Based Ultrahigh-Throughput Screening. ANALYTICAL CHEMISTRY 2016. In Press. Accepted August 2016. doi: 10.1021/acs.analchem.6b01712