Fucoidan-active α-L-fucosidases of the GH29 and GH95 families from a fucoidan degrading cluster of the marine bacterium Wenyingzhuangia fucanilytica.

In present work we provide the bioinformatic and biochemical characterization of six α-L-fucosidases that belong to the 29 and 95 families of glycoside hydrolases (GH) from the fucoidan-degrading locus of the marine bacterium Wenyingzhuangia fucanilytica CZ1127. The fucosidases FucWf1, FucWf2, FucWf3 and FucWf6 are relegated to the subfamily A of the GH29 family. The fucosidase FucWf4 bears a distant resemblance to the GH29 and does not belong to either the GH29A or the GH29B subfamilies. Apparently, FucWf4 is the first representative of a new subfamily within the GH29 family of α-L-fucosidases. For the first time the specificity of fucosidases has been studied using a series of fucoidan-related sulfated oligosaccharides. Studied α-L-fucosidases are able to cleave l-fucose from sulfated fucooligosacchrides after their treatment with exo-sulfatases. All studied α-L-fucosidases are cleaving the α-1→3- and α-1→4-linked terminal l-fucose in sulfated fucooligosaccharides. However, only FucWf3 is able to cleave off an α-1→2-linked l-fucose. The fucosidase FucWf5 of the GH95 family is shown to have higher activity on fucoidans than fucosidases of the GH29 family. Supposedly, the α-l-fucosidase FucWf5 participates in fucoidan debranching. The obtained data indicate different roles of fucosidases of the GH29 and GH95 families in the process of fucoidan degradation by the marine bacteria W. fucanilytica CZ1127.