4crq

Publication Abstract from PubMed

Laminarin is a beta-1,3-D-glucan displaying occasional beta-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 beta-1,3-glucanases [four belonging to glycosyl hydrolase family 16 (GH16) and one to GH64] with various modular architectures. Here, the characterization of the beta-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-beta-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.

Structural and biochemical characterization of the laminarinase ZgLamCGH16 from Zobellia galactanivorans suggests preferred recognition of branched laminarin.,Labourel A, Jam M, Legentil L, Sylla B, Hehemann JH, Ferrieres V, Czjzek M, Michel G Acta Crystallogr D Biol Crystallogr. 2015 Feb;71(Pt 2):173-84. doi:, 10.1107/S139900471402450X. Epub 2015 Jan 23. PMID:25664729^[1]

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