1769-06-8Relevant articles and documents
Binding of the Bacterial Adhesin FimH to Its Natural, Multivalent High-Mannose Type Glycan Targets
Sauer, Maximilian M.,Jakob, Roman P.,Luber, Thomas,Canonica, Fabia,Navarra, Giulio,Ernst, Beat,Unverzagt, Carlo,Maier, Timm,Glockshuber, Rudi
supporting information, p. 936 - 944 (2019/01/11)
Multivalent carbohydrate-lectin interactions at host-pathogen interfaces play a crucial role in the establishment of infections. Although competitive antagonists that prevent pathogen adhesion are promising antimicrobial drugs, the molecular mechanisms underlying these complex adhesion processes are still poorly understood. Here, we characterize the interactions between the fimbrial adhesin FimH from uropathogenic Escherichia coli strains and its natural high-mannose type N-glycan binding epitopes on uroepithelial glycoproteins. Crystal structures and a detailed kinetic characterization of ligand-binding and dissociation revealed that the binding pocket of FimH evolved such that it recognizes the terminal α(1-2)-, α(1-3)-, and α(1-6)-linked mannosides of natural high-mannose type N-glycans with similar affinity. We demonstrate that the 2000-fold higher affinity of the domain-separated state of FimH compared to its domain-associated state is ligand-independent and consistent with a thermodynamic cycle in which ligand-binding shifts the association equilibrium between the FimH lectin and the FimH pilin domain. Moreover, we show that a single N-glycan can bind up to three molecules of FimH, albeit with negative cooperativity, so that a molar excess of accessible N-glycans over FimH on the cell surface favors monovalent FimH binding. Our data provide pivotal insights into the adhesion properties of uropathogenic Escherichia coli strains to their target receptors and a solid basis for the development of effective FimH antagonists.
Simple one-pot regioselective 6-O-phosphorylation of carbohydrates and trehalose desymmetrization
Abragam Joseph,Chang, Chun-Wei,Wang, Cheng-Chung
supporting information, p. 11497 - 11499 (2013/12/04)
Biologically essential carbohydrate 6-phosphates, especially trehalose 6-phosphate, can be synthesized easily in excellent overall yields in 2 steps involving minimum protecting group manipulations. We can cleave the diphenylphosphate group for further synthetic objectives.
TMSOTf-catalyzed silylation: Streamlined regioselective one-pot protection and acetylation of carbohydrates
Joseph, A. Abragam,Verma, Ved Prakash,Liu, Xin-Yi,Wu, Chia-Hui,Dhurandhare, Vijay M.,Wang, Cheng-Chung
experimental part, p. 744 - 753 (2012/03/11)
A highly efficient TMSOTf-catalyzed HMDS silylation of sugars, which can easily be integrated with subsequent reactions in one-pot fashion, has been developed. Its usefulness was demonstrated by applications to streamlined regioselective one-pot protection and nonenzymatic acetylation of unprotected sugars. Monosaccharide and trehalose building blocks with orthogonally well-differentiated hydroxy groups were efficiently prepared starting with free sugars in one-pot fashion without the need for prior per-O-silylation. Regioselectively protected and acetylated building blocks were prepared directly from unprotected sugars in a one-pot manner involving up to five TMSOTf-catalyzed reactions, including a new TMSOTf-catalyzed silylation of carbohydrates. Copyright
