Characterization of novel Ostreococcus tauri starch binding domains

NICOLAS HEDIN; JULIETA BARCHIESI; DIEGO GOMEZ-CASATI; MA. VICTORIA BUSI

Congreso; IV Latinamerican Congress on Environmental and Algae Biotechnology (SOLABIAA); 2015

Starch Binding Domains (SBDs) are one type of carbohydrate binding domains (CBMs) that have acquired the evolutionary advantage of being able to interact and disrupt the substrate surface on a particular way. This can be accomplished because this kind of CBM presents two polysaccharide binding sites. The proteins containing these CBMs show a strong physical association with the different substrates, increasing the rate of enzymatic reactions. These modules occur also in proteins with no hydrolytic activity, constituting a core from which the catalytic proteins are organized. These properties make SBDs a very powerful molecular tool, allowing to us the possibility to engineering hydrolytic enzymes to increase its catalytic efficiencies when added in trans, and a powerful means of polysaccharide destructuration. In this work, we analyze the SBDs present in two degradative enzymes involved in starch catabolism in Ostreococcus tauri. One of these SBD belongs to the family CBM20 according to the CAZY classification. This SBD is part of the glucan 1,4-alpha-glucosidase (EC 3.2.1.3, Ot06g02060) that catalyze the hydrolysis of terminal 1,4-alpha-D-glucose residues from non-reducing ends. The second SBD belongs to the CBM48 family of the CAZY database and is present in the glycogen 6-alpha-D-glucanohydrolase (EC 3.2.1.68, Ot14g02550) that catalyze the hydrolysis of 1,6-alpha-D-glucosidic bonds in branched polysaccharides.