8.B.18 The Glucose PTS Inhibitor Dysgalacticin (Dysgalacticin) Family
Dysgalacticin is a large (21.5 kDa), heat-labile bacteriocin that is active against the human pathogen Streptococcus pyogenes (Heng et al., 2006). It is bactericidal towards S. pyogenes and inhibits glucose fermentation by non-growing cell suspensions. Dysgalacticin blocked transport of both glucose and 2DG, indicating that dysgalacticin targets the phosphoenolpyruvate-dependent glucose- and mannose-phosphotransferase system (PTS) of S. pyogenes. This inhibitory activity was voltage-independent, and in addition to inhibiting glucose transport, dysgalacticin increased the permeability of the cytoplasmic membrane mediating leakage of intracellular potassium ions. Moreover, dysgalacticin dissipated the membrane potential and inhibited [14C]serine uptake, a membrane potential-dependent process in S. pyogenes (Swe et al., 2009). Swe et al. (2010) have identified a small (57aa) protein of 2 TMSs called DysI of S. dysgalactiae (ABY63615) that serves as a dysgalacticin immunity protein, protecting cells from the action of dysgalacticin.