title: Structural and biochemical characterization of the laminarinase ZgLamCGH16 from Zobellia galactanivorans suggests preferred recognition of branched laminarin.
abstract: Laminarin is a β-1,3-D-glucan displaying occasional β-1,6 branches. This storage polysaccharide of brown algae constitutes an abundant source of carbon for marine bacteria such as Zobellia galactanivorans. This marine member of the Bacteroidetes possesses five putative β-1,3-glucanases [four belonging to glycosyl hydrolase family 16 (GH16) and one to GH64] with various modular architectures. Here, the characterization of the β-glucanase ZgLamC is reported. The catalytic GH16 module (ZgLamCGH16) was produced in Escherichia coli and purified. This recombinant enzyme has a preferential specificity for laminarin but also a significant activity on mixed-linked glucan (MLG). The structure of an inactive mutant of ZgLamCGH16 in complex with a thio-β-1,3-hexaglucan substrate unravelled a straight active-site cleft with three additional pockets flanking subsites -1, -2 and -3. These lateral pockets are occupied by a glycerol, an acetate ion and a chloride ion, respectively. The presence of these molecules in the vicinity of the O6 hydroxyl group of each glucose moiety suggests that ZgLamCGH16 accommodates branched laminarins as substrates. Altogether, ZgLamC is a secreted laminarinase that is likely to be involved in the initial step of degradation of branched laminarin, while the previously characterized ZgLamA efficiently degrades unbranched laminarin and oligo-laminarins.
authors: Sorbonne Universités, UPMC Université Paris 06, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, 29688 Roscoff CEDEX, France.
authors: Aurore
authors: A
authors: Labourel
authors: Sorbonne Universités, UPMC Université Paris 06, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, 29688 Roscoff CEDEX, France.
authors: Murielle
authors: M
authors: Jam
authors: Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 11 Allée de Beaulieu, CS 50837, 35708 Rennes CEDEX 7, France.
authors: Laurent
authors: L
authors: Legentil
authors: Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 11 Allée de Beaulieu, CS 50837, 35708 Rennes CEDEX 7, France.
authors: Balla
authors: B
authors: Sylla
authors: Sorbonne Universités, UPMC Université Paris 06, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, 29688 Roscoff CEDEX, France.
authors: Jan Hendrik
authors: JH
authors: Hehemann
authors: Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 11 Allée de Beaulieu, CS 50837, 35708 Rennes CEDEX 7, France.
authors: Vincent
authors: V
authors: Ferrières
authors: Sorbonne Universités, UPMC Université Paris 06, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, 29688 Roscoff CEDEX, France.
authors: Mirjam
authors: M
authors: Czjzek
authors: Sorbonne Universités, UPMC Université Paris 06, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, 29688 Roscoff CEDEX, France.
authors: Gurvan
authors: G
authors: Michel
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D044602:Cellulases / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D041965:Flavobacteriaceae / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D005936:Glucans / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011509:Proteoglycans; D016415:Sequence Alignment; D013379:Substrate Specificity; D047071:beta-Glucans / Q000737:chemistry / Q000378:metabolism
chemical_list: D005936:Glucans; D011509:Proteoglycans; D047071:beta-Glucans; C010770:polysaccharide-K; C008247:laminaran; D044602:Cellulases
keywords: GH16; algae; carbohydrate metabolism; glycoside hydrolase; laminarinase; marine bacteria; oligosaccharide; β-1,3-glucan