A novel glucosyltransferase from Streptococus mutans produces oligo-isomaltosaccharides

Streptococcus mutans secretes a sucrose-independent branching enzyme that utilizes isomaltosaccharides as donors for branching formation on dextran. Although the branching enzyme is necessary for the formation of extracellular polysaccharide complexes, the source of the donor for the enzyme is unknown. In this study, we purified a novel glucosyltransferase from S. mutans and characterized its properties. The glucosyltransferase was primer independent 1,6-α-D-glucan synthase, which produced oligo-isomaltosaccharides. The enzyme was thought to be a source of donor for the branching enzyme in S. mutans.