Browsing by Author "Prins, Ricardo"
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- ItemThe two oceans project : searching for novel carbohydrate sulfoconjugation enzymes(Stellenbosch : Stellenbosch University, 2017-03) Prins, Ricardo; Kossmann, Jens; Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics. Institute of Plant Biotechnology.ENGLISH ABSTRACT: Marine algae contain a wide range of carbohydrate-based bioactive compounds, which promote extra-nutritional health benefits. In marine algae, the most sought after bioactive compounds are sulfoconjugated polysaccharides (SPs) which have the potential to be used as functional ingredients in the nutraceuticals industry. SPs are of particular biological interest to human health and have been shown to exert anti-inflammatory, anti-tumorigenic, immunostimulatory, and more recently anti-viral activities. The specific biological properties of SPs are attributed to their monomer composition, sulfate content, and sulfoconjugation pattern present on the sugar backbone. The biochemical mechanisms through which these polysaccharides are sulfoconjugated are well characterised in animals and are catalysed by a superfamily of enzymes termed sulfotransferases (SULTs, EC 2.8.2). In vivo, SULTs are responsible for the enzymatic process termed sulfoconjugation. This entails the transfer of a sulfuryl group (SO3) from a donor molecule, classically 3’-phosphoadenosine 5’-phosphosulfate (PAPS), to an acceptor molecule e.g. alcohol, amine, sugar or phenolic compound. The current state-of-the-art involves the isolation and purification of sulfoconjugated compounds from marine organisms. These compounds are then tested for various bioactivities (Hamed et al., 2015; Wijesekara et al., 2011). In contrast, here we used a high-throughput RNA-seq approach to identify 18 putative SULT transcripts and subsequently isolated one carbohydrate SULT. Eight of the SULTs identified from the P. corallorhiza transcriptome had a Sulfotransfer_1 domain. However, four of the eight Sulfotransfer_1 SULTs also had a Sulfotransfer_3 domain. Additionally, seven SULTs had a Sulfotransfer_2 domain, with one also possessing a Gal-3-O_sulfotr domain. The SULTs identified with overlapping domains were not exclusively assigned to any one SULT family, as they had statistically significant homology (<0.05) to either the Sulfotransfer_1 and Sulfotransfer_3 or the Sulfotransfer_2 and the Gal-3-O_sulfotr domain containing SULT entries, respectively. Additionally, this approach included the diurnal sampling of a ubiquitously distributed red algal species, Plocamium corallorhiza, as a generic representative of the Rhodophyta phylum. A diurnal differential gene expression analysis was used to assess potential differences in gene expression, specifically with regard to galactan biosynthesis. Ultimately, 639 nocturnally differentially expressed genes (DEGs) were identified. However, no DEGs relating to galactan biosynthesis as it relates to starch and sucrose, galactose or sulfur metabolism pathways, were present within the 639 DEGs.