Metabolite-sensitive, ATP-dependent, protein kinase-catalyzed phosphorylation of HPr, a phosphocarrier protein of the phosphotransferase system in gram-positive bacteria.
In this review article we summarize the recent information available concerning important mechanistic and physiological aspects of the protein kinase-mediated phosphorylation of seryl residue-46 in HPr, a phosphocarrier protein of the phosphoenolpyruvate: sugar phosphotransferase system in Gram-positive bacteria. Emphasis is placed upon the information recently obtained in two laboratories through the use of site-specific mutants of the HPr protein. The results show that (i) in contrast to eukaryotic protein kinases, the HPr(ser) kinase recognizes the tertiary structure of HPr rather than a restricted part of the primary sequence of the protein; (ii) like seryl protein kinases of eukaryotes, the HPr(ser) kinase can phosphorylate a threonyl residue, but not a tyrosyl residue when such a residue replaces the regulatory seryl residue in position-46 of the protein; (iii) the regulatory consequences of seryl phosphorylation are due to the introduction of a negative charge at position-46 in the protein rather than the bulky phosphate group; and (iv) PTS protein-HPr interactions influence the conformation of HPr, thereby retarding or stimulating the rate of kinase-catalyzed seryl-46 phosphorylation. The physiological consequences of HPr(ser) phosphorylation in vivo are still a matter of debate.
Reizer
J
J
Department of Biology, University of California, San Diego, La Jolla 92093.
Deutscher
J
J
Saier
M H
MH
D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D006094:Gram-Positive Bacteria / Q000201:enzymology*; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000378:metabolism*; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism
D001426:Bacterial Proteins; D000255:Adenosine Triphosphate; D010770:Phosphotransferases; D011494:Protein Kinases; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr