Caractérisation structurale et fonctionnelle des endosulfatases humaines HSulfs, enzymes clés de l'édition de l'héparane sulfate ; Structural and functional characterization of the human endosulfatases HSulfs, key editing enzymes of heparan sulfate

Human endosulfatases HSulf-1 and HSulf-2 catalyze the 6-O-desulfation of the polysaccharide heparan sulfate (HS), a key cellular component used by cells as an external communication tool. By editing the sulfation patterns of HS, HSulfs regulate its biomolecular interaction properties. Despite their similar enzymatic activities in vitro, HSulfs often display form-dependent discrepancies in vivo, particularly in cancer, where HSulf-1 generally demonstrates anti-oncogenic properties while HSulf-2 shows pro-oncogenic effects. This work aims to characterize the structural and functional properties of HSulfs to understand the link between their unique structural characteristics and functional involvement. Using complementary analytical approaches, including chromatography, electrophoresis, mass spectrometry, and single molecule Imaging techniques, we investigated three main aspects: (1) the structural elements influencing HSulf-2 oligomerization, with particular emphasis on its CS/DS GAG chain and hydrophilic domain (HD), (2) the functional characteristics of HSulf endosulfatase activity, particularly substrate specificity, using a novel assay to assess HSulfs' reactivity towards specific oligosaccharide sequences and (3) the evaluation of sulfamate-modified oligosaccharides as potential specific inhibitors of HSulf activity. The results obtained provide new insights into our understanding of HSulf structure-function relationships and contribute to the growing knowledge base for potential therapeutic approaches targeting these enzymes. ; Les endosulfatases humaines HSulf-1 et HSulf-2 catalysent la 6-O-désulfatation de l'héparane sulfate (HS), un composant majeur de la matrice extracellulaire, essentiel à la communication cellulaire. La modification des motifs de sulfatation de l'HS par HSulfs module ses propriétés d'interaction. Bien qu'ayant des activités enzymatiques similaires in vitro, les HSulfs présentent in vivo une dualité fonctionnelle, notamment dans le cancer où HSulf-1 est généralement anti-oncogénique et ...