Characterization of oligosaccharides produced by a truncated dextransucrase from Weissella confusa Wcp3a isolated from pozol, a traditional fermented corn beverage

Glucansucrase Dsr_Wcp3a from a Weissella confusa strain discovered in fermented maize (pozol) was produced in E. coli BL21 resulting in three truncated forms of the native enzyme. An important modification of specificity is observed, as the truncated enzymes synthesize low molecular weight dextran from sucrose, probably due to the absence of domains IV and V, compared to the native enzyme which produces high molecular weight dextran. Low molecular weight dextran is obtained from the non-processive addition of glucose molecules to sucrose (FIMOS) and glucose (IMOS), resulting in two gluco-isomalto-oligosaccharide series. The exclusive synthesis of IMOS occurs in reactions where glucose is included as acceptor in reactions with sucrose as glucosyl donor substrate, due to a higher affinity for glucose as acceptor. The truncated forms also synthesize OS with maltose as acceptor.