Pyrophosphate-Producing Protein Dephosphorylation by HPr Kinase/Phosphorylase: A Relic of Early Life?

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 99; no. 21; pp. 13442 - 13447
• Main Authors: Mijakovic, Ivan, Poncet, Sandrine, Galinier, Anne, Monedero, Vicente, Fieulaine, Sonia, Janin, Joël, Nessler, Sylvie, Marquez, José Antonio, Scheffzek, Klaus, Hasenbein, Sonja, Hengstenberg, Wolfgang, Deutscher, Josef
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 15-10-2002; National Acad Sciences; The National Academy of Sciences
• Subjects: Bacillus subtilis - genetics; Bacillus subtilis - metabolism; Bacteria; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Binding Sites; Biochemistry; Biochemistry, Molecular Biology; Biological Evolution; Biological Sciences; Cell growth; Chromatography; Diphosphates; Diphosphates - metabolism; Enzymes; Genes; Lactobacillus casei - enzymology; Lactobacillus casei - genetics; Lead; Life Sciences; Phosphates; Phosphoenolpyruvate Sugar Phosphotransferase System - chemistry; Phosphoenolpyruvate Sugar Phosphotransferase System - genetics; Phosphoenolpyruvate Sugar Phosphotransferase System - metabolism; Phosphoprotein Phosphatases - chemistry; Phosphoprotein Phosphatases - genetics; Phosphoprotein Phosphatases - metabolism; Phosphorylation; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Proteins; Radioactive decay; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.212410399

In most Gram-positive bacteria, serine-46-phosphorylated HPr (P-Ser-HPr) controls the expression of numerous catabolic genes (≈10% of their genome) by acting as catabolite corepressor. HPr kinase/phosphorylase (HprK/P), the bifunctional sensor enzyme for catabolite repression, phosphorylates HPr, a phosphocarrier protein of the sugar-transporting phosphoenolpyruvate/glycose phosphotransferase system, in the presence of ATP and fructose-1,6-bisphosphate but dephosphorylates P-Ser-HPr when phosphate prevails over ATP and fructose-1,6-bisphosphate. We demonstrate here that P-Ser-HPr dephosphorylation leads to the formation of HPr and pyrophosphate. HprK/P, which binds phosphate at the same site as the β phosphate of ATP, probably uses the inorganic phosphate to carry out a nucleophilic attack on the phosphoryl bond in P-Ser-HPr. HprK/P is the first enzyme known to catalyze P-protein dephosphorylation via this phosphophosphorolysis mechanism. This reaction is reversible, and at elevated pyrophosphate concentrations, HprK/P can use pyrophosphate to phosphorylate HPr. Growth of Bacillus subtilis on glucose increased intracellular pyrophosphate to concentrations (≈6 mM), which in in vitro tests allowed efficient pyrophosphate-dependent HPr phosphorylation. To effectively dephosphorylate P-Ser-HPr when glucose is exhausted, the pyrophosphate concentration in the cells is lowered to 1 mM. In B. subtilis, this might be achieved by YvoE. This protein exhibits pyrophosphatase activity, and its gene is organized in an operon with hprK.