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Publication Abstract from PubMed

Laminarinase is commonly used to describe [beta]-1,3-glucanases widespread throughout Archaea, bacteria and several eukaryotic lineages. Some [beta]-1,3-glucanases have already been structurally and biochemically characterized, but very few from organisms that are in contact with genuine laminarin, the storage polysaccharide of brown algae. Here we report the heterologous expression and subsequent biochemical and structural characterization of ZgLamAGH16 from Zobellia galactanivorans, the first GH16 laminarinase from a marine bacterium associated with seaweeds. ZgLamAGH16 contains a unique additional loop, compared to other GH16 laminarinases, which is composed of 17 amino-acids and gives a bent shape to the active cleft of the enzyme. This particular topology is perfectly adapted to the U-shape conformation of laminarin chains in solution, and thus explains the predominant specificity of ZgLamAGH16 for this substrate. The 3D structure of the enzyme and two enzyme-substrate complexes, one with laminaritetraose, the other with a trisaccharide of 1,3-1,4-[beta]-D-glucan, have been determined at 1.5 A, 1.35 A and 1.13 A resolution, respectively. The structural comparison of substrate recognition pattern between these complexes allow the proposition that ZgLamAGH16 likely diverged from an ancestral broad specificity GH16 beta-glucanase and evolved toward a bent active site topology adapted to efficient degradation of algal laminarin.

The beta-Glucanase ZgLamA from Zobellia galactanivorans evolved a bent active site adapted for efficient degradation of algal laminarin.,Labourel A, Jam M, Jeudy A, Hehemann JH, Czjzek M, Michel G J Biol Chem. 2013 Dec 11. PMID:24337571^[1]

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