Presence of an Invertase-Like Enzyme and a Sucrose Permeation System in Strains of Streptococcus mutans

Abstract

Enzyme preparations obtained from sonically-treated washed cells of Streptococcus mutans strain GS5 were found to contain ‘sucrase’ activity which was distinct from that of the glucosyl and fructosyl transferases known to be elaborated by this organism. This ‘sucrase’ activity was formed constitutively and could be separated from transferase activity by agarose chromatography. The enzyme appears similar, if not identical, to invertase on the basis of its catalytic action, its molecular size, and its heat sensitivity. Its presence in cells of Strep, mutans strain GS5 indicates that this organism is not solely dependent upon the glucosyl and fructosyl transferases for the utilization of sucrose for growth. The total observable ‘sucrase’ activity of glucose grown cells of Strep, mutans strains GS5 and 6715 was found to increase markedly when the organisms were treated with toluene, indicating they were relatively impermeable to sucrose. Untreated sucrose grown cells exhibited 10-fold higher total ‘sucrase’ activity than did untreated glucose grown cells, suggesting that growth in sucrose broth resulted in the induction of a sucrose transport system.

Sucrolytic enzymes from human dental plaque in saliva

“…The three sucrolytic enzymes are all shown to occur in cariogenic streptococci of dental plaque (CRITCHLEY, WOOD, SAXTON & LEACH 1967, GIBBONS 1972 and other sucrolytic enzymes are shown to occur in different oral streptococci (NEW- BRUN & BAKER 1968). The thick plaque, containing proteolytic bacteria below its surface, and the thin plaque, consisting of almost only streptococci, seem to give the same proportions of enzyme of this type, as ratio of glucose to total monohexose was ne,ar]y the same in high and low enzyme producers.…”

Streptococcus mutans Dextransucrase: Stimulation of Glucan Formation by Phosphoglycerides

“…4) may be important for future attempts to determine the functioning of this enzyme in promoting the cariogenicity of S. mutans. Because the polar hydrophilic head and nonpolar hydrophobic hydrocarbon tail of phosphoglycerides give these molecules unique physical properties, the association of dextransucrase with phospholipids during or after excretion from the S. mutans cell could partially explain the highly aggregated state of the enzyme in culture fluids (13,14,20,24,25,33), the multiple forms of the enzyme routinely found during purification (5,17), the variations in the forms of the enzyme produced under different growth conditions (22,39,42), and the ability of partially purified enzyme to attach specifically to the S. mutans cell surface (41). In addition, the stimulation of dextransucrase by serum and oral secretions (3,9,14,26,27,37) could involve interactions with the phospholipids known to occur in these fluids (21,30,34).…”

Four Types of Streptococcus mutans Based on Their Genetic, Antigenic and Biochemical Characteristics

“…It is known that sucrose is metabolized more rapidly if cells are grown in sucrose (Tanzer, Brown & Meyers, 1972). Thus the fate of sucrose is determined, at least in part, by an inducible system, probably invertase (Gibbons, 1972;Tanzer, Brown & --7 7 11 I c h j Mclnerney, 1973). The experiments u ith fructose reported here demonstrate that in genetic group I strains, rapid fructose metabolism is, like the metabolism of sucrose, not constitutive (as it is in other strains) but is induced by growth in sucrose.…”