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X-ray structure of the HPr kinase/phosphatase from Staphylococcus xylosus at 1.95 A resolution
Structural highlights
FunctionHPRK_STAXY Catalyzes the ATP- as well as the pyrophosphate-dependent phosphorylation of 'Ser-46' in HPr, a phosphocarrier protein of the phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS). HprK/P also catalyzes the pyrophosphate-producing, inorganic phosphate-dependent dephosphorylation (phosphorolysis) of seryl-phosphorylated HPr (P-Ser-HPr). The two antagonistic activities of HprK/P are regulated by several intracellular metabolites, which change their concentration in response to the absence or presence of rapidly metabolisable carbon sources (glucose, fructose, etc.) in the growth medium. Therefore, by controlling the phosphorylation state of HPr, the HprK/P is a sensor enzyme that plays a major role in the regulation of carbon metabolism and sugar transport: it mediates carbon catabolite repression (CCR), and regulates PTS-catalyzed carbohydrate uptake and inducer exclusion. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe histidine containing phospho carrier protein (HPr) kinase/phosphatase is involved in carbon catabolite repression, mainly in Gram-positive bacteria. It is a bifunctional enzyme that phosphorylates Ser-46-HPr in an ATP-dependent reaction and dephosphorylates P-Ser-46-HPr. X-ray analysis of the full-length crystalline enzyme from Staphylococcus xylosus at a resolution of 1.95 A shows the enzyme to consist of two clearly separated domains that are assembled in a hexameric structure resembling a three-bladed propeller. The N-terminal domain has a betaalphabeta fold similar to a segment from enzyme I of the sugar phosphotransferase system and to the uridyl-binding portion of MurF; it is structurally organized in three dimeric modules exposed to form the propeller blades. Two unexpected phosphate ions associated with highly conserved residues were found in the N-terminal dimeric interface. The C-terminal kinase domain is similar to that of the Lactobacillus casei enzyme and is assembled in six copies to form the compact central hub of the propeller. Beyond previously reported similarity with adenylate kinase, we suggest evolutionary relationship with phosphoenolpyruvate carboxykinase. In addition to a phosphate ion in the phosphate-binding loop of the kinase domain, we have identified a second phosphate-binding site that, by comparison with adenylate kinases, we believe accommodates a product/substrate phosphate, normally covalently linked to Ser-46 of HPr. Thus, we propose that our structure represents a product/substrate mimic of the kinase/phosphatase reaction. Structure of the full-length HPr kinase/phosphatase from Staphylococcus xylosus at 1.95 A resolution: Mimicking the product/substrate of the phospho transfer reactions.,Marquez JA, Hasenbein S, Koch B, Fieulaine S, Nessler S, Russell RB, Hengstenberg W, Scheffzek K Proc Natl Acad Sci U S A. 2002 Mar 19;99(6):3458-63. PMID:11904409[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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