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Publication Abstract from PubMed

The Polysaccharide Lyase Family 6 (PL6) represents one of the 41 polysaccharide lyase families classified in the CAZy database with the vast majority of its members being alginate lyases grouped into three subfamilies, PL6_1-3. To decipher the mode of recognition and action of the enzymes belonging to subfamily PL6_1, we solved the crystal structures of Pedsa0632, Patl3640, Pedsa3628 and Pedsa3807, which all show different substrate specificities and mode of action (endo-/exo-lyase). Thorough exploration of the structures of Pedsa0632 and Patl3640 in complex with their substrates as well as docking experiments confirm that the conserved residues in subsites -1 to +3 of the catalytic site form a common platform which can accommodate various types of alginate in a very similar manner but with a series of original adaptations bringing them their specificities of action. From comparative studies with existing structures of PL6_1 alginate lyases, we observe that in the right-handed parallel beta-helix fold shared by all these enzymes, the substrate binding site harbors the same overall conserved structures and organization. Despite this apparent similarity, it appears that members of the PL6_1 subfamily specifically accommodate and catalyze the degradation of different alginates suggesting that this common platform is actually a highly adaptable and specific tool.

Exploring molecular determinants of polysaccharide Lyase family 6-1 enzyme activity.,Violot S, Galisson F, Carrique L, Jugnarain V, Conchou L, Robert X, Thureau A, Helbert W, Aghajari N, Ballut L Glycobiology. 2021 Jul 10. pii: 6318796. doi: 10.1093/glycob/cwab073. PMID:34245266^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.