Protein-carbohydrate interactions play a key role in the first step of numerous biological processes, e.g. fertilization and tissue homing of immune cells, but also in infection, inflammation, migration of tumor cells and other pathologies. Pathogenic microorganisms (viruses, bacteria, fungi and parasites) have developed strategies for utilizing glycan epitopes on human tissues for specific recognition, for adhesion and sometimes for cellular internalization. The proteins involved can be viral capsid domains, adhesins on top of pili, soluble lectins or carbohydrate binding domains of enzymes or toxins. Their carbohydrate-binding sites are specific for glycans located on human epithelia such as the histo/blood group oligosaccharides of ABO and Lewis systems. Molecules that could interfere with such lectin/glycan interaction are therefore of high interest as anti-infectious agents. Similarly, human lectins are involved in chronic diseases related to inflammation and cancer, and consequently the search for lectin inhibitors to interfere with these pathological conditions is of outstanding interest. The project described here aims at the development of the underexplored area of non-carbohydrate drug-like lectin inhibitors. Such glycomimetics could overcome current limitations of carbohydrate-based therapeutics such as poor pharmacokinetic and pharmacodynamic parameters as well as provide solution for synthetic tractability The consortium of two French and two German laboratories proposes to combine a multidisciplinary approach combining virtual and in vitro screening of chemical libraries, using functional assays and NMR approaches, followed by structure (X-ray, NMR), thermodynamics (ITC) and kinetics (SPR, MD) guided lead optimization.In order to explore the neglected area of chemical space for the development of lectin inhibitors, we plan a highly diverse three-pillar screening strategy, using virtual and experimental screening on three representative examples of bacterial lectins. Selected screening hits from these complementary screening campaigns will be analyzed in silico and validated in biochemical secondary assays. Commercial analogs of these hits will then establish a stringent structure-activity relationship supported by chemo-informatics analysis. Next, kinetic and thermo-dynamic characterization and subsequent structure elucidation using highly complementary biophysical techniques will provide monovalent lead struc-tures. This cyclic iterative process then yields monovalent inhibitors that are assembled onto multivalent scaffolds to pave the way for highly potent non-carbohydrate glycomimetics for bacterial lectins All optimized compounds will be assessed for their efficacy in lectin-dependent bacterial adhesion assays. This proposal aims at the establishment of a broadly applicable methodology for the development of non-carbohydrate lectin inhibitors. A set of three diverse and representative bacterial lectins was chosen to explore the potential of the discovery pipeline. While pipeline development is our major concern, generating novel anti-infectives is foreseen (i.e. a problem-solving endeavor). However, this approach will not be limited to bacterial targets and other viral, fungal, or human lectins of high therapeutic significance can be targeted as well. Using our technology, the scientific community and also companies will be able to develop potential drugs for lectin-mediated diseases, e.g. metastasizing cancers, autoimmune disorders or other infectious diseases. This is certainly a significant improvement to currently pharmaceutically neglected lectins and paves the ground for targeting lectins with drugs. Finally, this endeavor will contribute to our fundamental understanding of biological processes involving multivalent receptors such as membrane dynamics and lipid raft-mediated internalization (i.e. a curiosity driven research).