Abstract:
Bioactive sulfated fucoidans have high fucose content and are derived from brown seaweeds. Here we report the
discovery of the first cold-adapted endo-α(1 → 3)-fucoidanase (EC 3.2.1.211), Psf1. The psf1 gene was found in
the genome of Pseudoalteromonas sp. S3178, a bacterium isolated from a shrimp near Antarctica. Phylogenetic
analyses designated Psf1 as a putative member of glycoside hydrolase family 107 (GH107). Substrate selectivity
analysis confirmed Psf1 as being endo-acting and indicated that the enzyme catalyzes hydrolysis of α(1 → 3)-
glycosidic fucoidan linkages. Psf1 had temperature optimum of 10–30 ◦C but retained activity at 1 ◦C. Structural
modeling indicated similarity to the crystal structure of P5A_FcnA (Psychromonas sp. SW5A), yet distinct high
variability regions were identified by RMSF. Psf1 released low molecular weight fucoidan oligosaccharides from
Saccharina latissima fucoidan that dose-dependently reduced IL-12p40 secretion in dendritic cells, and lowered
IFN-γ and IL-10 levels in dendritic cells co-cultured with allogeneic CD4+ T-cells, without affecting IL-17
secretion, indicating a suppression of Th1-mediated immune response. Treatment of dendritic cells with
native fucoidan from S. latissima did not affect cell viability or cytokine secretion. These findings have potential
to enable new enzyme-assisted production, at low temperatures, of bioactive fucoidan oligosaccharides from
S. latissima grown in the Northern Hemisphere