Characterization of the 1-phosphohistidinyl residue in the phosphocarrier protein HPr of the phosphoenolpyruvate: sugar phosphotransferase system of Streptococcus faecalis

The phosphocarrier protein HPr of the bacterial phosphoenolpyruvate:sugar phosphotransferase system contains 1-phosphohistidine at residue 15. This residue and the active site residue Arg-17 are conserved in HPrs isolated from both Gram-positive and -negative bacteria. The pH- and temperature-dependent hydrolysis of the 1-phosphohistidinyl residue in P-HPr from Streptococcus faecalis has been investigated. The results show that the hydrolysis properties are very similar to those previously reported for P-HPr from Escherichia coli. It was postulated that the unusual hydrolysis properties were due to the presence of a carboxyl group at the active site, and it is now known that in HPr from Escherichia coli the C-terminal residue Glu-85 is present. The results in this paper suggest that a similar carboxyl group is present at the active site in HPr from Streptococcus faecalis.