ANALYSIS OF A PRIMER-INDEPENDENT GTF-I FROM STREPTOCOCCUS-SALIVARIUS

A glucosyltransferase (GTF) gene, designated gtfL, from Streptococcus salivarius was cloned and expressed in Escherichia coli and its nucleo tide sequence determined. The GTF-L enzyme catalysed the synthesis of water-insoluble glucan in a primer-independent manner. The nucleotide sequence and derived amino acid sequence of GTF-L were similar in size and domain structure to previously sequenced glucosyltransferases. Ho wever, a 464-bp region of high variability was identified which could be selectively amplified from strains of S. salivarius by the polymera se chain reaction and could therefore form the basis for species ident ification. No sequence-specific motifs related to the solubility and l inkage of the glucan product or its need for a dextran primer could be ascertained.