Utilization of natural fucosylated oligosaccharides by three novel alpha-L-fucosidases from a probiotic Lactobacillus casei strain
2011
Rodríguez-Díaz, Jesús | Monedero García, Vicente | Yebra Yebra, María Jesús
Three putative α-l-fucosidases encoded in the Lactobacillus casei BL23 genome were cloned and purified. The proteins displayed different abilities to hydrolyze natural fucosyloligosaccharides like 2′-fucosyllactose, H antigen disaccharide, H antigen type II trisaccharide, and 3′-, 4′-, and 6′-fucosyl-GlcNAc. This indicated a possible role in the utilization of oligosaccharides present in human milk and intestinal mucosa. l-Fucose is one of the most common monosaccharides occurring at the nonreducing end of many glycans on mammalian cell surfaces, intestinal mucin, blood group antigens, and human milk oligosaccharides (HMO) (2). α-l-Fucosidases (EC 3.2.1.51), which are exoglycosidases capable of cleaving α-linked l-fucose residues from fucosyloligosaccharides, play important roles in the adaptation of bacteria to particular niches. Therefore, infant intestinal bacteria such as bifidobacteria are able to use HMO (4, 9). The genome of Bifidobacterium longum strains carries gene clusters related to the utilization of these substrates (8), which contain the necessary activities to degrade all of their glycosidic linkages, including α-l-fucosidases. In Bifidobacterium bifidum, two α-l-fucosidases, AfcA and AfcB, have been characterized as belonging to glycoside hydrolase (GH) families 95 and 29, respectively, and degrade α-(1,2)- and α-(1,3/4)-fucosylated HMO, respectively (1, 3). However, there are no reports of α-l-fucosidases in lactobacilli, another important group of probiotic bacteria which are common inhabitants of the human intestine. Genome analysis of 25 Lactobacillus species reveals that only the Lactobacillus casei-Lactobacillus rhamnosus group encodes putative α-l-fucosidases (6).
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