Induction and catabolite repression in Staphylococcus aureus phosphoenolpyruvate : lactose phosphotransferase system

Abstract

Synthesis of sugar-specific components of phosphosphoenolpyruvate : lactose phosphofransferase system (lac-PTS) in Staphylococcus aureus AF 121 was induced by galactose and lactose. No induction was obesrved with IPTG ; instead, it repressed strongly the uninduced synthesis of the enzymes. Glucose and other metabolizable sugars mannose, fructose, and mannitol-repressed the enzyme synthesis both in the presence and absence of the inducer, galactose. Unexpectedly, the repression appeared to be much stronger on uninduced than induced synthesis of the enzymes, suggesting that the induction and the repression might compete at some step(s) in the enzyme synthesis. An extremely strong repression comparable to that by glucose was observed with 2-deoxy-D-glucose(2DG), inducating that metabolism beyond 6-phosphorylation was not required for 2 DG and glucose to exert their repressing actions.