Diego Reyes-Weiss1, Bjørn Pedersen1, Nanna Rhein-Knudsen1, Bjørge Westereng1, Svein J. Horn1
1Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
Fucoidans are a heterogeneous group of sulfated polysaccharides found in the cell wall of brown seaweeds and occurring in a wide variety of arrangements. At the simplest, they are composed of α-L-fucose units arranged as an α-1,3-, or an alternated α-1,3;α-1,4-, linear backbone with varying degree of sulfation at carbon 2, 3, and 4. Additionally, fucoidans can be branched, acetylated, and contain galactose, xylose, mannose, rhamnose, glucose, and uronic acids units. Fucoidans have attractive valorization prospects due to several reported biological activities. However, the complex and largely undefined structure of fucoidans is a major challenge in the understanding and further study of their biologically active motifs. Fucoidan-active enzymes, found in many marine bacteria, are classified into different glycosyl hydrolase (GH) families within the carbohydrate-active enzyme database (CAZy). Different types of enzymatic activities have been described, including endo– and exo-fucoidanases, sulfatases, and carbohydrate esterases, all potential enzymatic tools for processing of fucoidans and for structural elucidation. Recently, the genome of Lentimonas sp. CC4, a marine bacterium highly specialized in fucoidan degradation, was sequenced revealing 284 putative fucoidan-active enzymes. In this study, we have carried out a bioinformatical mining of fucoidan-active enzymes from Lentimonas sp. CC4. Blasting the sequence of previously described fucoidanases and sulfatases led to the selection and cloning of 4 putative exo-fucoidanases, 6 putative endo-fucoidanases, and 4 putative sulfatases. All these enzymes have been successfully expressed in E. coli and tested on fucoidans from 9 different brown seaweeds using a range of analytical methods.