Les organismes eucaryotes sont les principaux producteurs de glycanes acides, qui sont impliqués dans de nombreux processus biologiques. Les bactéries ont développé des enzymes capables de dégrader ces sucres complexes, les polysaccharide lyases. Ce travail a porté sur la caractérisation biochimique et structurale d’une famille de ces enzymes, PL33, et a notamment révélé la proximité entre les PL33 et des épimérases eucaryotes impliquées dans la modification des glycanes acides.
Nos partenaires :
Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Univ, CNRS, INRAE,
Biotechnologie et Biodiversité Fongiques INRAE,
Department of Biology, University of York,
Department of Biochemistry, Cell and Systems Biology, University of Liverpool,
Newcastle University Biosciences Institute, Newcastle University,
School of Life Sciences, Keele University,
Department of Biology, Technology Facility, University of York,
Computational Biology Facility, MerseyBio, University of Liverpool,
Department of Biological Sciences, King Abdulaziz University,
Department of Biotechnology and Biomedicine (DTU Bioengineering), Technical University of Denmark,
School of Life Sciences, University of Essex,
York Structural Biology Laboratory, University of York,
York Biomedical Research Institute, University of York,
Résumé :
« Acidic glycans are essential for the biology of multicellular eukaryotes. To utilize them, microbial life including symbionts and pathogens has evolved polysaccharide lyases (PL) that cleave their 1,4 glycosidic linkages via a β-elimination mechanism. PL family 33 (PL33) enzymes have the unusual ability to target a diverse range of glycosaminoglycans (GAGs), as well as the bacterial polymer, gellan gum. In order to gain more detailed insight into PL33 activities we recombinantly expressed 10 PL33 members derived from all major environments and further elucidated the detailed biochemical and biophysical properties of five, showing that their substrate specificity is conferred by variations in tunnel length and topography. The key amino acids involved in catalysis and substrate interactions were identified, and employing a combination of complementary biochemical, structural, and modeling approaches, we show that the tunnel topography is induced by substrate binding to the glycan. Structural and bioinformatic analyses revealed that these features are conserved across several lyase families as well as in mammalian GAG epimerases »
L’article est disponible en libre accès sur le site de l’Editeur : https://www.pnas.org/doi/10.1073/pnas.2421623122
