No abstract

The g t f S gene, coding for a glucosyltransferase which synthesizes water-soluble glucan and previously cloned from Streptococcus downei strain MFe28 (mutans serotype A) into a bacteriophage vector, was subcloned into a plasmid vector. The g t f S gene products expressed in Escherichia coli were compared to the primer-independent, oligoisomaltosaccharide synthase in Sfreptococcus sobrinus strain AHT (mutans serotype g) and shown to resemble it closely in molecular mass, isoelectric point, immunological properties, optimum pH and K , values. The glucans produced from sucrose by the g t f S gene products are a-1,6-linked linear oligo-isomaltosaccharides without any branching sites. A similar g t f S gene was also detected on chromosomal DNA from S. sobrinus strain AHT.