1fu0
From Proteopedia
CRYSTAL STRUCTURE ANALYSIS OF THE PHOSPHO-SERINE 46 HPR FROM ENTEROCOCCUS FAECALIS
Structural highlights
FunctionPTHP_ENTFA General (non sugar-specific) component of the phosphoenolpyruvate-dependent sugar phosphotransferase system (sugar PTS). This major carbohydrate active-transport system catalyzes the phosphorylation of incoming sugar substrates concomitantly with their translocation across the cell membrane. The phosphoryl group from phosphoenolpyruvate (PEP) is transferred to the phosphoryl carrier protein HPr by enzyme I. Phospho-HPr then transfers it to the permease (enzymes II/III). P-Ser-HPr interacts with the catabolite control protein A (CcpA), forming a complex that binds to DNA at the catabolite response elements cre, operator sites preceding a large number of catabolite-regulated genes. Thus, P-Ser-HPr is a corepressor in carbon catabolite repression (CCR), a mechanism that allows bacteria to coordinate and optimize the utilization of available carbon sources. P-Ser-HPr also plays a role in inducer exclusion, in which it probably interacts with several non-PTS permeases and inhibits their transport activity (By similarity). 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 phosphocarrier protein HPr is a central component of the phosphoenolpyruvate:sugar phosphotransferase system (PTS), which transfers metabolic carbohydrates across the cell membrane in many bacterial species. In Gram-positive bacteria, phosphorylation of HPr at conserved serine 46 (P-Ser-HPr) plays several regulatory roles within the cell; the major regulatory effect of P-Ser-HPr is its inability to act as a phosphocarrier substrate in the enzyme I reaction of the PTS. In order to investigate the structural nature of HPr regulation by phosphorylation at Ser46, the structure of the P-Ser-HPr from the Gram- positive bacterium Enterococcus faecalis has been determined. X-ray diffraction analysis of P-Ser-HPr crystals provided 10,043 unique reflections, with a 95.1 % completeness of data to 1.9 A resolution. The structure was solved using molecular replacement, with two P-Ser-HPr molecules present in the asymmetric unit. The final R-value and R(Free) are 0.178 and 0.239, respectively. The overall tertiary structure of P-Ser-HPr is that of other HPr structures. However the active site in both P-Ser-HPr molecules was found to be in the "open" conformation. Ala16 of both molecules were observed to be in a state of torsional strain, similar to that seen in the structure of the native HPr from E. faecalis. Regulatory phosphorylation at Ser46 does not induce large structural changes to the HPr molecule. The B-helix was observed to be slightly lengthened as a result of Ser46 phosphorylation. Also, the water mediated Met51-His15 interaction is maintained, again similar to that of the native E. faecalis HPr. The major structural, and thus regulatory, effect of phosphorylation at Ser46 is disruption of the hydrophobic interactions between EI and HPr, in particular the electrostatic repulsion between the phosphoryl group on Ser46 and Glu84 of EI and the prevention of a potential interaction of Met48 with a hydrophobic pocket of EI. The 1.9 A resolution structure of phospho-serine 46 HPr from Enterococcus faecalis.,Audette GF, Engelmann R, Hengstenberg W, Deutscher J, Hayakawa K, Quail JW, Delbaere LT J Mol Biol. 2000 Nov 3;303(4):545-53. PMID:11054290[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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