Jean-Maurice Mallet (DR CNRS), Laurent Cattiaux (AI CNRS)
Oligosaccharides are widely present at the cell membrane, bound to a protein core or a lipid. They are hydrophilic and point to the outside of the cell. This thick layer of carbohydrates is called glycocalix (sugar layer).
These glycoconjugates are synthesized in the Golgi and then transported to the surface. They are then modified in situ by glycosidases and their composition therefore has a rapid adaptive cellular response to the environment.
This glycocalyx has different known roles, it protects the cell first (against dehydration, nonspecific adhesions, proteases …) but is also involved in more specific interactions: it is in direct contact with the immune system and exposed to extracellular proteins (adhesins, growth factor, antibodies and more generally lectins) and plays a crucial role in triggering the immune response and in cellular communications.
A special feature of carbohydrate / protein interactions is multivalence and clustering: on the one hand, many copies of carbohydrate epitopes are present on the surface of cells and, on the other hand, carbohydrate binding proteins are multivalent ( oligomers), . This leads to a strong cooperative bond (« velcro principle ») even if the isolated interactions are rather weak (mM range)
The main limitation of biological studies is the absence of defined oligosaccharides or more generally of pure glycoconjugates, as well as the absence of models imitating the multivalent presentation of carbohydrates.
In this regard, we are developing synthetic tools to address the role of these sugars in various pathologies in which carbohydrate / antibody (or other protein) interactions are involved. The applications are in diagnosis in non-adhesive therapies or vaccines.
Glycosaminoglycanes and analogues (ANR Homeogag, A Di Nardo, A Prochiantz, K Bouchemal)
Glycosaminoglycans are heterogeneous oligosaccharides, ubiquitous in the surfaces of eukaryotic cells and in the extracellular matrix. They play very different roles depending on their location and structure. This may be involved in blood clotting, activation of growth factors (FGF) or cytokines. We are preparing defined molecules targeting homeoprotein (Otx2, engrailed 2 ..) and HSV2 herpes virus envelope proteins.
- Toward libraries of biotinylated chondroitin sulfate analogs: from synthesis to in vivo studies G Despras, C Bernard, A Perrot, L Cattiaux , A Prochiantz , H Lortat-Jacob, J-M Mallet; Chemistry Eur J 2013, DOI: 10.1002/chem.201202173
- Hexagonal-shaped chondroitin sulfate self-assemblies have exalted anti-HSV-2 activity; A Galus, J-M Mallet, D Lembo, V Cagno, M Djabourov, H Lortat-Jacob, K Bouchemal; Carbohydr Polym, 2016, 136, 113-20. 10.1016 /j.carbpol.2015.08.054
- Protecting group strategies towards sulfated glycosaminoglycans; H Ledru, P Matton, J-Maurice Mallet and Chrystel Lopin-Bon Chapter 10 in Protecting Groups in Carbohydrate Chemistry ed/ Sebastien Vidal Wiley, 2018 ISBN: 978-3-527-34010-1
Oligomannosides (ANR caBMT, Y Guerardel, B Sendid)
Candida albicans is a commensal yeast present on our skin and in our intestines. It is usually harmless, but it becomes a pathogen for vulnerable and immunocompromised patients. Systemic candidiasis is then one of the nosocomial infections and is characterized by a very high mortality (50%). Understanding the modes of communication between the host and the pathogen is essential and depends largely on surface oligomannosides. In collaboration with Daniel Poulain / Boualem Sendid group (CHU Lille), we have shown that cell wall mannans can act as adhesins and antigens. We have prepared beta-oligomannosides (1-> 2) and alpha (1-> 2) di and tetra-mannosides (Candida Albicans antigens) for the development of early diagnostic tools.
- Mantyl tagged oligo beta (1-> 2) mannosides as Candida Albicans beta-mannosyltransferases substrates: a comparison between synthetic strategies M Pourcelot, L Cattiaux, G Sfihi-Loualia, E Fabre, F Krzewinsky, C Fradin, B Coddeville, E Maes, D Poulain, F Delplace, Y Guérardel, J-M Mallet RSC Adv., 2013, 3 (44), 22560 – 22571, doi:10.1039/C3RA43340D
- Characterization of the recombinant Candida albicans ?-1,2 mannosyltransferase Bmt1 involved in the initiation of ?-mannosylation of the yeast cell-wall phosphopeptidomannan E Fabre, G Sfihi-Loualia, M Pourcelot, B Coddeville, F Krzewinski, J Bouckaert, E Maes, R Dubois, C Fradin, J.-M Mallet, D Poulain, F Delplace,Y Guérardel Biochem J. 2014, 347 360, doi:10.1042/BJ20131012
- Characterization of the recombinant Candida albicans beta-1,2 mannosyltransferase Bmt3p involved in the ?-mannosylation of cell-wall phosphopeptidomannan Ghenima Sfihi-Loualia, Thomas Hurtaux, Emeline Fabre, Anaïs Mée, Marilyne Pourcelot, Emmanuel Maes, Julie Bouckaert, Frédéric Krzewinski, Chantal Fradin, Jean-Maurice Mallet, Boualem Sendid, Daniel Poulain, Florence Delplace and Yann Guérardel. Glycobiology, 2015, doi 10.1093/glycob/cwv094
- Beta1,2 Mannosyltransferases 1 and 3 Participate in Yeast and Hyphae O-and N-Linked Mannosylation and Alter Candida albicans Fitness during Infection Flavie Courjol, Thierry Jouault, Céline Mille, Rebecca Hall, Emmanuel Maes, Boualem Sendid, Jean Maurice Mallet, Yann Guerardel, Neil A.R. Gow, Daniel Poulain, Chantal Fradin Open Forum Infect Dis. 2015 Sep 10;2 (3):ofv116. doi: 10.1093/ofid/ofv116.
- Candida albicans ?-1,2 mannosyl transferase Bmt3: preparation and evaluation of a ?(1,2),?(1,2)- tetramannosyl fluorescent substrate Laurent Cattiaux, Anaïs Mée, Marilyne Pourcelot, Ghenima Sfihi-Loualia, Thomas Hurtaux, Emmanuel Maes, Chantal Fradin, Thierry Jouault, Emeline Fabre, Florence Delplace, Yann Guérardel, Jean-Maurice Mallet, Bioorg Med Chem, 2016, doi 10.1016/j.bmc.2016.02.008
- Evaluation of monovalent and multivalent iminosugars to modulate Candida albicans ?-1,2 mannosyltransferase CaBmt1 and CaBmt3 enzyme activities; Thomas Hurtaux, Ghenima Sfihi-Loualia, Yoan Brissonnet, Julie Bouckaert, Jean-Maurice Mallet, Boualem Sendid, Florence Delplace, Emeline Fabre, Sébastien Gouin, Yann Guérardel Carbohydrate Res, 2016, doi: 10.1016/j.carres.2016.01.004
L-fucose is a rare but important sugar present on the N-glucan chain (poly N-acetyl lactosamine). Synthetic oligosaccharides showed unprecedented specific 3D conformations.
- Dimerization of the fungal defense lectin CCL2 is essential for its toxicity against nematodes; S Bleuler-Martinez, K Stutz, R Sieber, M Collot, J-M Mallet, M Hengartner, M Schubert, A Varrot, M Künzler; Glycobiology, 2016, 27, 486-500
- A secondary structure element in a wide range of fucosylated glyco-epitopes T Aeschbacher, M Zierke, M Smieško, M Collot, J-M Mallet, B Ernst, F H.-T. Allain, M Schubert, Chemistry 2017, 11598–11610, 10.1002/chem.201701866
For high avidity, multivalent glycoconjugate models are needed.
in a first approach, we have prepared mannodendrimers containing up to 27 mannoses) showing a nice cooperative effect on the DC-sign lectin. (up to * 40) (Collab F Fieschi, IBS Grenoble)
in a second approach, we study micrometric droplets of soybean oil functionalized with a fluorescent mannolipid. We have shown that surface mannosides are recognized by model lectin (concanavalin A) and by macrophage lectins leading to their phagocytosis. Lateral mobility at the surface of the droplets indeed creates a powerful clustering effect.
- New branched amino acids for very high affinity dendrimeric DC-sign ligands L Cattiaux, V Porkolab; F Fieschi, J-M Mallet, Bioorg Med Chem. 2018, 26, 1006-1015
Glycopeptides / Peptides
Antibodies have been found in patients with autoimmune diseases (multiple sclerosis and Rett syndrome) against abnormal glucosylation of the protein (Glc Asn residue). We synthesized glucopeptides and evaluated with patient sera to define a structural consensus of antigens and a better characterization of antibodies. We are also interested in glycoreplicate, a peptide that cross-reacts with carbohydrate antigens.
- Glaser Oxidative Coupling on Peptides: Stabilization of β Turn Structure via a 1,3-Butadiyne Constrain; N Auberger, M Di Pisa, Maud Larregola, Gérard Chassaing, E Peroni, S Lavielle, A-M Papini, O Lequin, J- M Mallet; Bioorg Med Chem 22, 2014, 6924-6932, 10.1016/j.bmc.2014.10.026
- Antibody Recognition in Multiple Sclerosis and Rett Syndrome Using a Collection of Linear and Cyclic N-Glucosylated Antigenic Probes; F R Fernández, M Di Pisa, G Rossi, N Auberger, O Lequin, M Larregola, A Benhora, C Mansuy, G Chassaing, F Lolli, J Hayek, S Lavielle, P Rovero, J-M Mallet, A M Papini; Biopolymers, 2015, 104, 560-76 10.1002/bip.22677
- Multi-stage mass spectrometry analysis of sugar-conjugated beta-turn structures to be used as probes in autoimmune diseases; C Giangrande, N Auberger, J-M Mallet, S Lavielle, A M Papini, J Vinh; J Am Soc Mass Spectrom, 2016, 735-47 doi./10.1007/s13361-015-1321-9127.
- Glycoreplica peptides to investigate molecular mechanisms of immune-mediated physiological versus pathological conditions A Mazzoleni, P Rovero, J-M Mallet, A Ma Papini Arch Biochem Biophys, 2018; 663,44-53. doi: 10.1016/j.abb.2018.12.030.
Further reading (general public)