Abstract
Many algae are rich sources of sulfated polysaccharides with biological activities. The physicochemical/rheological properties and biological activities of sulfated polysaccharides are affected by the pattern and number of sulfate moieties. Sulfation of carbohydrates is catalyzed by carbohydrate sulfotransferases (CHSTs) while modification of sulfate moieties on sulfated polysaccharides was presumably catalyzed by sulfatases including formylglycine-dependent sulfatases (FGly-SULFs). Post-translationally modification of Cys to FGly in FGly-SULFs by sulfatase modifiying factors (SUMFs) is necessary for the activity of this enzyme. The aims of this study are to mine for sequences encoding algal CHSTs, FGly-SULFs and putative SUMFs from the fully sequenced algal genomes and to infer their phylogenetic relationships to their well characterized counterparts from other organisms. Algal sequences encoding CHSTs, FGly-SULFs, SUMFs, and SUMF-like proteins were successfully identified from green and brown algae. However, red algal FGly-SULFs and SUMFs were not identified. In addition, a group of SUMF-like sequences with different gene structure and possibly different functions were identified for green, brown and red algae. The phylogeny of these putative genes contributes to the corpus of knowledge of an unexplored area. The analyses of these putative genes contribute toward future production of existing and new sulfated carbohydrate polymers through enzymatic synthesis and metabolic engineering.
Highlights
Sulfates are found in algal proteins, carbohydrate, sulfolipids, and low molecular weight sulfated compounds (DeBoer, 1981)
Sequences that do not match with any sequences encoding carbohydrate sulfotransferases (CHSTs), FGly-SULFs, and sulfatase modifiying factors (SUMFs) were removed upon the reciprocal search
Human CHSTs, FGly-SULFs, and SUMFs were used for the mining and phylogenetic analyses in this study mainly because sequences from human were the best characterized in terms of sequence and functions compared to those from other organisms
Summary
Sulfates are found in algal proteins, carbohydrate, sulfolipids, and low molecular weight sulfated compounds (DeBoer, 1981). Many algae were reported to be rich sources of sulfated polysaccharides with biological activities (Hernandez-Sebastia et al, 2008). Sulfated fucans from brown algae and sulfated galactans from green and red algae have been reported to be potent anticoagulant agents (Pomin and Mourão, 2008). Some of these algal sulfated polysaccharides such as agar, agarose, and carrageenan, constitute the major component of algal extracellular matrix or. APS can either be phosphorylated by APS kinase or reduced by glutathione-dependent APS reductase Both enzymes and pathways are important for cellular synthesis of sulfated and reduced sulfur compounds in algae, respectively (Gao et al, 2000). The pattern and number of these substitutions affect the physicochemical/rheological properties of sulfated polysaccharides and their biological activities (Opoku et al, 2006; Tuvikene et al, 2008)
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