Streptococcus mutans phosphoenolpyruvate:fructose phosphotransferase sugar transport system (Fru-PTS)

The Streptococcus mutans phosphoenolpyruvate:fructose phosphotransferase sugar transport system (Fructose PTS) is a specialized bacterial complex responsible for the active transport and phosphorylation of fructose (Wen et al., 2001). As the primary pathogen in dental caries, S. mutans utilizes this system to internalize dietary sugars, which are subsequently fermented into organic acids that demineralize tooth enamel (Ajdic et al., 2002). The system comprises general cytoplasmic proteins, Enzyme I and HPr, alongside sugar-specific membrane-bound Enzyme II components such as the inducible FruI and the constitutive FruCD (Gauthier et al., 1984). In addition to its metabolic role, the Fructose PTS is a critical regulator of carbon catabolite repression, influencing the expression of genes related to biofilm formation and stress response (Zeng & Burne, 2016). This transport system is a significant target for preventive dental therapies, most notably through the use of the sugar substitute xylitol (Trahan, 1995). Xylitol is recognized by the FruI permease and phosphorylated to xylitol-5-phosphate, a toxic intermediate that cannot be further metabolized, leading to the inhibition of glycolysis and bacterial proliferation (Tanzer et al., 2006). Other agents, such as the antibiotic streptozotocin and certain polyphenols like epigallocatechin gallate (EGCG), also interact with or inhibit this system to exert antimicrobial effects (Sekiya et al., 2019).

Other names

Fructose-specific phosphotransferase systemFructose PTSPEP:fructose phosphotransferase systemEIIFrufruI/fruCD system

Xylitol acts as a competitive substrate that is internalized and phosphorylated to xylitol-5-phosphate, which inhibits glycolysis and bacterial growth. Streptozotocin is an antibiotic analog that is taken up by the system to exert bactericidal effects.