Four glucosyltransferases, GtfJ, GtfK, GtfL and GtfM, from Streptococcus salivarius ATCC 25975

Abstract

The four recombinant glucosyltransferases (GTFs), GtfJ, GtfK, GtfL and GtfM, that had previously been cloned from Streptococcus salivarius ATCC 25975, were individually expressed in Escherichia coli and their glucan products and kinetic properties were analysed. GtfJ was a primer-dependent GTF which synthesized an insoluble glucan composed mainly of a-(1 + 3)-linked glucosyl residues in the presence of dextran 1-10. GtfK was primer-stimulated, and produced a linear soluble dextran without any detectable branch points both in the absence and in the presence of dextran 1-10. GtfL was primerindependent and produced a mixed-linkage insoluble glucan composed of approximately equal proportions of a-(l-+ 3)-and a-(1 + 6)-linked glucosyl residues. GtfL was inhibited by dextran T-10. G t f M was primer-independent and produced a soluble dextran with approximately 5% a-(1 + 3)-linked glucosyl residues. G t f M was essentially unaffected by the presence of dextran T-10. The results confirmed that each enzyme represented one of the four possible combinations of primer-dependency and product solubility and that each possessed unique biosynthetic properties. The soluble dextrans formed by GtfK and GtfM, as well as the mixed-linkage insoluble glucan formed by GtfL, were also capable of acting as primers for the primer-dependent GtfJ and the primer-stimulated GtfK. Unexpectedly, the linear dextran produced by GtfK was by far the least effective either at priming itself or at activating and priming the pr i mer-de pendent GtfJ .

Evolution of Cariogenic Character in Streptococcus mutans: Horizontal Transmission of Glycosyl Hydrolase Family 70 Genes

“…2) are considered to have replicated by tandem duplication, a phenomenon observed in Str. mutans 21 , Streptococcus salivarius 22, and Streptococcus criceti and in the lactic acid bacterium, Lcb. reuteri (Fig.…”

Phylogenetic Analysis of Glucosyltransferases and Implications for the Coevolution of Mutans Streptococci with Their Mammalian Hosts

“…Gtfs are prevalent among the homofermentative lactic acid bacteria, including the oral species of Streptococcus and Lactobacillus , as well as in species of Leuconostoc and Lactobacillus isolated from fermented foods or the environment [7]. The number of glucosyltransferase genes found in a given species may vary from one to four [8], with each enzyme synthesizing a different type of glucan depending on the nature of the glucosidic bond. Water-soluble glucans (WSG), also known as dextran, are rich in α-1,6 glucosidic linkages, while a higher content of α-1,3 glucosidic linkages is characteristic of water-insoluble glucans (WIG), also known as mutan [9].…”

Expression of a streptococcal glucosyltransferase as a fusion to a solute-binding protein in Lactobacillus fermentum BR11

“…Insoluble glucans with K(1^3) linkages are not oxidised by periodic acid and are therefore poorly stained with Schi¡ reagent. Since GtfJ forms a predominantly insoluble K(1^3) linked product [21], the very intense bands formed by the BspAĜ tfJ fusion expressing strains indicate a much higher level of glucan synthesis than the parent.…”