PROPERTIES OF THE GLUCOSE PHOSPHOTRANSFERASE SYSTEM OF CLOSTRIDIUM-ACETOBUTYLICUM NCIB 8052

The glucose phosphotransferase system (PTS) of Clostridium acetobutylicum was studied by using cell extracts. The system exhibited a K(m) for glucose of 34-mu-M, and glucose phosphorylation was inhibited competitively by mannose and 2-deoxyglucose. The analogs 3-O-methylglucoside and methyl alpha-glucoside did not inhibit glucose phosphorylation significantly. Activity showed no dependence on Mg2+ ions or on pH in the range 6.0 to 8.0. The PTS comprised both soluble and membrane-bound proteins, which interacted functionally with the PTSs of Clostridium pasteurianum, Bacillus subtilis, and Escherchia coli. In addition to a membrane-bound enzyme II(Glc), sugar phosphorylation assays in heterologous systems incorporating extracts of pts mutants of other organisms provided evidence for enzyme I, HPr, and III(Glc) components. The HPr was found in the soluble fraction of C. acetobutylicum extracts, whereas enzyme I, and probably also III(Glc), was present in both the soluble and membrane fractions, suggesting a membrane location in the intact cell.