Regulation of glycerol and maltose uptake by the IIAGlc-like domain of IINag of the phosphotransferase system in Salmonella typhimurium LT2

Abstract

In Enterobacteriaceae the nonphosphorylated form of IIAGlc of the phosphoenolpyruvate-dependent phosphotransferase system (PTS) can inhibit the uptake and subsequent metabolism of glycerol and maltose by binding to, and inhibiting, glycerol kinase and the MalK protein of the maltose transport system, respectively. In this report we show that the IIAGlc-like domain of the membrane-bound IIN-acetylglucosamine (IINag) of the PTS can replace IIAGlc in a Salmonella typhimurium crr mutant strain that lacks all soluble IIAGlc. The inhibition was most severe in cells which were partially induced for the glycerol or maltose uptake systems. The Streptococcus thermophilus lactose transporter LacS, which also contains a IIAGlc-like domain, could not replace IIAGlc. Neither IINag nor LacS could replace IIAGlc in activation of adenylate cyclase.