title: Uronic polysaccharide degrading enzymes.
abstract: In the past several years progress has been made in the field of structure and function of polysaccharide lyases (PLs). The number of classified polysaccharide lyase families has increased to 23 and more detailed analysis has allowed the identification of more closely related subfamilies, leading to stronger correlation between each subfamily and a unique substrate. The number of as yet unclassified polysaccharide lyases has also increased and we expect that sequencing projects will allow many of these unclassified sequences to emerge as new families. The progress in structural analysis of PLs has led to having at least one representative structure for each of the families and for two unclassified enzymes. The newly determined structures have folds observed previously in other PL families and their catalytic mechanisms follow either metal-assisted or Tyr/His mechanisms characteristic for other PL enzymes. Comparison of PLs with glycoside hydrolases (GHs) shows several folds common to both classes but only for the β-helix fold is there strong indication of divergent evolution from a common ancestor. Analysis of bacterial genomes identified gene clusters containing multiple polysaccharide cleaving enzymes, the Polysaccharides Utilization Loci (PULs), and their gene complement suggests that they are organized to process completely a specific polysaccharide.
authors.affiliation: Aix-Marseille University, AFMB UMR7257, 163 Avenue de Luminy, 13288 Marseille, France; CNRS, AFMB UMR7257, 163 Avenue de Luminy, 13288 Marseille, France.
authors.forename: Marie-Line
authors.initials: ML
authors.lastname: Garron
authors.affiliation: Department of Biochemistry, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada. Electronic address: miroslaw.cygler@usask.ca.
authors.forename: Miroslaw
authors.initials: M
authors.lastname: Cygler
mesh_terms: D050260:Carbohydrate Metabolism; D019143:Evolution, Molecular; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000378:metabolism; D006868:Hydrolysis; D008958:Models, Molecular; D008968:Molecular Conformation; D010802:Phylogeny; D011133:Polysaccharide-Lyases / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D013379:Substrate Specificity
chemical_list: D011134:Polysaccharides; D006026:Glycoside Hydrolases; D011133:Polysaccharide-Lyases