Dual phosphorylation of Mycoplasma pneumoniae HPr by Enzyme I and HPr kinase suggests an extended phosphoryl group susceptibility of HPr.
In Gram-positive bacteria, the HPr protein of the phosphoenolpyruvate:sugar phosphotransferase system can be phosphorylated at two distinct sites, His-15 and Ser-46. While the former phosphorylation is implicated in phosphoryl transfer to the incoming sugars, the latter serves regulatory purposes. In Bacillus subtilis, the two phosphorylation events are mutually exclusive. In contrast, doubly phosphorylated HPr is present in cell extracts of Mycoplasma pneumoniae. In this work, we studied the ability of the two single phosphorylated HPr species to accept a second phosphoryl group. Indeed, both Enzyme I and the HPr kinase/phosphorylase from M. pneumoniae are able to use phosphorylated HPr as a substrate. The formation of doubly phosphorylated HPr is substantially slower as compared to the phosphorylation of free HPr. However, the rate of formation of doubly phosphorylated HPr is sufficient to account for the amount of HPr(His approximately P)(Ser-P) detected in M. pneumoniae cells.
Halbedel
Sven
S
Abteilung für Allgemeine Mikrobiologie, Institut für Mikrobiologie und Genetik der Georg-August-Universität Göttingen, Grisebachstrasse 8, D-37077 Göttingen, Germany.
Stülke
Jörg
J
D001426:Bacterial Proteins / Q000378:metabolism*; D004926:Escherichia coli; D007700:Kinetics; D009177:Mycoplasma pneumoniae / Q000378:metabolism*; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000378:metabolism*; D010766:Phosphorylation; D017852:Phosphotransferases (Nitrogenous Group Acceptor) / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*
D001426:Bacterial Proteins; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr; C110847:HPr kinase; D017346:Protein Serine-Threonine Kinases; D017852:Phosphotransferases (Nitrogenous Group Acceptor); C022360:phosphoenolpyruvate-protein phosphotransferase