Dominant ptsH mutations of the gene coding for synthesis of the HPr protein of the phosphoenolpyruvate-dependent phosphotransferase system in Escherichia coli K-12 merodiploids

Abstract The Escherichia coli ptsI and ptsH genes code for the synthesis of two proteins of the phosphoenolpyruvate-dependent phosphotransferase system (PTS), namely enzyme I and protein HPr. A number of ptsI + ptsH + /F′ ptsI + ptsH merodiploids was obtained. It was shown in experiments in vivo that ptsH mutations in the transposition are dominant. Bacterial extracts from these merodiploids supported [ 14 C] methyl glucoside (MG) phosphorylation at the expense of phosphoenolpyruvate only half as much as extracts from the pts + cells. ptsI + ptsH /F′ ptsI + ptsH + merodiploids appeared to be non-viable; the reason for this lack of viability is discussed.