Substitution of aspartate and glutamate for active center histidines in the Escherichia coli phosphoenolpyruvate : sugar phosphotransferase system maintain phosphotransfer potential

The active center histidines of the Escherichia coli phosphoenolpyruvate:su gar phosphotransferase system proteins; histidine-containing protein, enzym e I, and enzyme HAG(Glc) were substituted with a series of amino acids (ser ine, threonine, tyrosine, cysteine, aspartate, and glutamate) with the pote ntial to undergo phosphorylation. The mutants [H189E]enzyme I, [H15D]HPr, a nd [H90E]enzyme IIA(Glc) retained ability for phosphorylation as indicated by [P-32]phosphoenolpyruvate labeling. As the active center histidines of b oth enzyme I and enzyme IIA(Glc) undergo phosphorylation of the N-epsilon2 atom, while HPr is phosphorylated at the N-delta1 atom, a pattern of succes sful substitution of glutamates for N-epsilon2 phosphorylations and asparta tes for N-delta1 phosphorylations emerges. Furthermore, phosphotransfer bet ween acyl residues: P-aspartyl to glutamyl and P-glutaxnyl to aspartyl was demonstrated with these mutant proteins and enzymes.