Specific binding between bacterial enterotoxins and oligosaccharides on the host cell membrane is a paradigm for protein-sugar interaction. One of the best characterized recognition pairs is formed by ganglioside GM1 and the cholera toxin (CT). Recently, Krengel's group has identified a second binding site, which appears to be present in the close CT congener LT and in CT from the El Tor strain, responsible for the current cholera pandemic. This binding site, which is clearly distinct from the primary GM1 binding site, recognizes blood group ABO antigens, fucosylated carbohydrate structures carried on both glycolipids and glycoproteins. The main objective of our project is to develop new dual-site ligands for cholera toxin inhibition featuring 2 pharmacophoric fragments, a GM1 mimic and a blood group mimic, connected across a linker able to span the two binding sites of enterotoxins. The GM1 binding site will be targeted using a functionalized GM1 mimic recently developed in the host laboratory which binds to CT and allows conjugation to aglycons. The blood group binding site will be targeted by selecting the mimimal blood group epitope using STD NMR experiments. Linkers of different lengths will be built in modular fashion by connecting PEG monoamine fragments using squaric acid connectors. Optimal linker length will be selected by combinatorial target-guided dynamic synthesis of a disulfide library in the presence of hLTB or CTB/hLTB toxin hybrids as templates. The required proteins will be obtained through a collaboration with the Krengel group. This project is connected to the activities of the COST D34/001/05 WG, working on cholera toxin inhibition and sensing. This fellowship and the framework provided by the COST group will ensure the opportunity for the proposer to be exposed to an interdisciplinary context while working on a timely scientific project resulting from the coordinated efforts of internationally recognized research leaders in glycoscience.
Specific binding between bacterial enterotoxins and oligosaccharides on the host cell membrane is a paradigm for protein-sugar interaction. One of the best characterized recognition pairs is formed by ganglioside GM1 and the cholera toxin (CT). Recently, Krengel's group has identified a second binding site, which appears to be present in the close CT congener LT and in CT from the El Tor strain, responsible for the current cholera pandemic. This binding site, which is clearly distinct from the primary GM1 binding site, recognizes blood group ABO antigens, fucosylated carbohydrate structures carried on both glycolipids and glycoproteins. The main objective of our project is to develop new dual-site ligands for cholera toxin inhibition featuring 2 pharmacophoric fragments, a GM1 mimic and a blood group mimic, connected across a linker able to span the two binding sites of enterotoxins. The GM1 binding site will be targeted using a functionalized GM1 mimic recently developed in the host laboratory which binds to CT and allows conjugation to aglycons. The blood group binding site will be targeted by selecting the mimimal blood group epitope using STD NMR experiments. Linkers of different lengths will be built in modular fashion by connecting PEG monoamine fragments using squaric acid connectors. Optimal linker length will be selected by combinatorial target-guided dynamic synthesis of a disulfide library in the presence of hLTB or CTB/hLTB toxin hybrids as templates. The required proteins will be obtained through a collaboration with the Krengel group. This project is connected to the activities of the COST D34/001/05 WG, working on cholera toxin inhibition and sensing. This fellowship and the framework provided by the COST group will ensure the opportunity for the proposer to be exposed to an interdisciplinary context while working on a timely scientific project resulting from the coordinated efforts of internationally recognized research leaders in glycoscience.