Transporter Protein
PtsH


    Transport Function
Transporter Name: PtsH
Transporter Type: Phosphotransferase System (PTS)
Transporter Family: GPTS (TC#: 4.A)
General PTS
Transporter Subfamily: Hpr
Substrate/Function: ?
TC#: 
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    Genome Locus
PID:   16078454     Blast
Source:   Bacillus subtilis 168
Chromosome:   -
Location:   1458851..1459117
Gene:   Bsu1392
Length:  88
Strand:  +
Code:   G (Carbohydrate transport and metabolism)
COG:   COG1925
Product:  histidine-containing phosphocarrier protein of the phosphotransferase system (PTS) (HPr protein)
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    Transmembrane Segment
TMSs: 
TMHMM Server 
Total:     0
Topology:   >PtsH
MAQKTFKVTADSGIHARPATVLVQTASKYDADVNLEYNGKTVNLKSIMGVMSLGIAKGAEITISASGADE
NDALNALEETMKSEGLGE
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    Sequence
Protein Sequence: >PtsH 16078454 histidine-containing phosphocarrier protein of the phosphotransferase system (PTS) (HPr protein) [Bacillus subtilis 168]
MAQKTFKVTADSGIHARPATVLVQTASKYDADVNLEYNGKTVNLKSIMGVMSLGIAKGAEITISASGADE
NDALNALEETMKSEGLGE
DNA Sequence: >PtsH 16078454 histidine-containing phosphocarrier protein of the phosphotransferase system (PTS) (HPr protein) [Bacillus subtilis 168]
ATGGCACAAAAAACATTTAAAGTAACTGCAGATTCTGGAATCCATGCTCGTCCTGCGACAGTTCTTGTAC
AAACTGCTAGCAAATACGACGCTGACGTTAATTTAGAATATAACGGCAAAACAGTTAACCTTAAATCTAT
TATGGGTGTTATGTCTTTAGGTATCGCTAAAGGCGCTGAGATCACAATCTCTGCTTCCGGAGCTGACGAA
AACGATGCTCTTAACGCTTTAGAAGAAACAATGAAAAGCGAAGGACTCGGCGAGTAA
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    Publications
Publications on this gene:
1.  J Mol Microbiol Biotechnol 2007 ; 1-3(13):165-71.
Control of the phosphorylation state of the HPr protein of the phosphotransferase system in Bacillus subtilis: implication of the protein phosphatase PrpC.

Singh KD ,Halbedel S ,Görke B ,Stülke J ,

Abteilung für Allgemeine Mikrobiologie, Georg-August-Universität Göttingen, Göttingen, Germany.

In the Gram-positive bacterium Bacillus subtilis as well as in other firmicutes, the HPr protein of the phosphotransferase system (PTS) has two distinct phosphorylation sites, His-15 and Ser-46. These sites are phosphorylated by the Enzyme I of the PTS and by the ATP-dependent HPr kinase/phosphorylase, respectively. As a result, the phosphorylation state of HPr reflects the nutrient supply of the cell and is in turn involved in several responses at the levels of transport activity and expression of catabolic genes. Most important, HPr(Ser-P) serves as a cofactor for the pleiotropic transcription regulator CcpA. In addition to the proteins that phosphorylate HPr, those that are involved in the dephosphorylation are important in controlling the overall HPr phosphorylation state and the resulting regulatory and physiological outputs. In this study, we found that in addition to the phosphorylase activity of the HPr kinase/phosphorylase, the serine/threonine protein phosphatase PrpC uses HPr(Ser-P) as a target.

Publication Type: Research Support, Non-U.S. Gov't;

2.  Proc Natl Acad Sci U S A 2002 Oct 15; 21(99):13437-41.
X-ray structure of a bifunctional protein kinase in complex with its protein substrate HPr.

Fieulaine S ,Morera S ,Poncet S ,Mijakovic I ,Galinier A ,Janin J ,Deutscher J ,Nessler S ,

Laboratoire d'Enzymologie et Biochimie Structurales, Unité Propre de Recherche (UPR) 9063, Centre National de la Recherche Scientifique (CNRS), 91198 Gif-sur-Yvette, France.

HPr kinase/phosphorylase (HprK/P) controls the phosphorylation state of the phosphocarrier protein HPr and regulates the utilization of carbon sources by Gram-positive bacteria. It catalyzes both the ATP-dependent phosphorylation of Ser-46 of HPr and its dephosphorylation by phosphorolysis. The latter reaction uses inorganic phosphate as substrate and produces pyrophosphate. We present here two crystal structures of a complex of the catalytic domain of Lactobacillus casei HprK/P with Bacillus subtilis HPr, both at 2.8-A resolution. One of the structures was obtained in the presence of excess pyrophosphate, reversing the phosphorolysis reaction and contains serine-phosphorylated HPr. The complex has six HPr molecules bound to the hexameric kinase. Two adjacent enzyme subunits are in contact with each HPr molecule, one through its active site and the other through its C-terminal helix. In the complex with serine-phosphorylated HPr, a phosphate ion is in a position to perform a nucleophilic attack on the phosphoserine. Although the mechanism of the phosphorylation reaction resembles that of eukaryotic protein kinases, the dephosphorylation by inorganic phosphate is unique to the HprK/P family of kinases. This study provides the structure of a protein kinase in complex with its protein substrate, giving insights into the chemistry of the phospho-transfer reactions in both directions.

Publication Type: Comparative Study; Research Support, Non-U.S. Gov't;

4.  Protein Sci 1997 Oct ; 10(6):2107-19.
Phosphorylation on histidine is accompanied by localized structural changes in the phosphocarrier protein, HPr from Bacillus subtilis.

Jones BE ,Rajagopal P ,Klevit RE ,

University of Washington, Department of Biochemistry and Biomolecular Structure Center, Seattle 98195-7742, USA.

The histidine-containing protein (HPr) of bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) serves a central role in a series of phosphotransfer reactions used for the translocation of sugars across cell membranes. These studies report the high-definition solution structures of both the unphosphorylated and histidine phosphorylated (P-His) forms of HPr from Bacillus subtilis. Consistent with previous NMR studies, local conformational adjustments occur upon phosphorylation of His 15, which positions the phosphate group to serve as a hydrogen bond acceptor for the amide protons of Ala 16 and Arg 17 and to interact favorably with the alpha-helix macrodipole. However, the positively charged side chain of the highly conserved Arg 17 does not appear to interact directly with phospho-His 15, suggesting that Arg 17 plays a role in the recognition of other PTS enzymes or in phosphotransfer reactions directly. Unlike the results reported for Escherichia coli P-His HPr (Van Nuland NA, Boelens R, Scheek RM, Robillard GT, 1995, J Mol Biol 246:180-193), our data indicate that phosphorylation of His 15 is not accompanied by adoption of unfavorable backbone conformations for active site residues in B. subtilis P-Ser HPr.

Publication Type: Research Support, U.S. Gov't, P.H.S.;

5.  J Bacteriol 1996 Aug ; 15(178):4611-9.
Cold shock stress-induced proteins in Bacillus subtilis.

Graumann P ,Schröder K ,Schmid R ,Marahiel MA ,

Biochemie, Fachbereich Chemie, Philipps-Universität Marburg, Germany.

Bacteria respond to a decrease in temperature with the induction of proteins that are classified as cold-induced proteins (CIPs). Using two-dimensional gel electrophoresis, we analyzed the cold shock response in Bacillus subtilis. After a shift from 37 to 15 degrees C the synthesis of a majority of proteins was repressed; in contrast, 37 proteins were synthesized at rates higher than preshift rates. One hour after cold shock, the induction of CIPs decreased, and after 2 h, general protein synthesis resumed. The identified main CIPs were excised from two-dimensional gels and were subjected to microsequencing. Three small acidic proteins that showed the highest relative induction after cold shock were highly homologous and belonged to a protein family of which one member, the major cold shock protein, CspB, has previously been characterized. Two-dimensional gel analyses of a cspB null mutant revealed that CspB affects the level of induction of several CIPs. Other identified CIPs function at various levels of cellular physiology, such as chemotaxis (CheY), sugar uptake (Hpr), translation (ribosomal proteins S6 and L7/L12), protein folding (PPiB), and general metabolism (CysK, Ilvc, Gap, and triosephosphate isomerase).

Publication Type: Research Support, Non-U.S. Gov't;

6.  Mol Microbiol 1995 Sep ; 5(17):953-60.
Specific recognition of the Bacillus subtilis gnt cis-acting catabolite-responsive element by a protein complex formed between CcpA and seryl-phosphorylated HPr.

Fujita Y ,Miwa Y ,Galinier A ,Deutscher J ,

Department of Biotechnology, Faculty of Engineering, Fukuyama University, Hiroshima, Japan.

Catabolite repression of various Bacillus subtilis catabolic operons which carry a cis-acting catabolite-responsive element (CRE), such as the gnt operon, is mediated by CcpA, a protein belonging to the GalR-Lacl family of bacterial transcriptional repressors/activators, and the seryl-phosphorylated form of HPr, a phosphocarrier protein of the phosphoenolpyruvate:sugar phosphotransferase system. Footprinting experiments revealed that the purified CcpA protein interacted with P-ser-HPr to cause specific protection of the gnt CRE against DNase I digestion. The specific recognition of the gnt CRE was confirmed by the results of footprinting experiments using mutant gnt CREs carrying one of the following base substitutions within the CRE consensus sequence: G to T at position +149 or C to T at position +154 (+1 is the gnt transcription initiation nucleotide). The two mutant CREs causing a partial relief from catabolite repression were not protected by the CcpA/P-ser-HPr complex in footprinting experiments. Based on these and previous findings, we propose a molecular mechanism underlying catabolite repression in B. subtilis mediated by CcpA and P-ser-HPr.

Publication Type: Research Support, Non-U.S. Gov't;

7.  J Bacteriol 1994 Jun ; 11(176):3336-44.
Loss of protein kinase-catalyzed phosphorylation of HPr, a phosphocarrier protein of the phosphotransferase system, by mutation of the ptsH gene confers catabolite repression resistance to several catabolic genes of Bacillus subtilis.

Deutscher J ,Reizer J ,Fischer C ,Galinier A ,Saier MH Jr,Steinmetz M ,

Max Planck Institute for Molecular Physiology, Dortmund, Germany.

In gram-positive bacteria, HPr, a phosphocarrier protein of the phosphoenolpyruvate:sugar phosphotransferase system (PTS), is phosphorylated by an ATP-dependent, metabolite-activated protein kinase on seryl residue 46. In a Bacillus subtilis mutant strain in which Ser-46 of HPr was replaced with a nonphosphorylatable alanyl residue (ptsH1 mutation), synthesis of gluconate kinase, glucitol dehydrogenase, mannitol-1-P dehydrogenase and the mannitol-specific PTS permease was completely relieved from repression by glucose, fructose, or mannitol, whereas synthesis of inositol dehydrogenase was partially relieved from catabolite repression and synthesis of alpha-glucosidase and glycerol kinase was still subject to catabolite repression. When the S46A mutation in HPr was reverted to give S46 wild-type HPr, expression of gluconate kinase and glucitol dehydrogenase regained full sensitivity to repression by PTS sugars. These results suggest that phosphorylation of HPr at Ser-46 is directly or indirectly involved in catabolite repression. A strain deleted for the ptsGHI genes was transformed with plasmids expressing either the wild-type ptsH gene or various S46 mutant ptsH genes (S46A or S46D). Expression of the gene encoding S46D HPr, having a structure similar to that of P-ser-HPr according to nuclear magnetic resonance data, caused significant reduction of gluconate kinase activity, whereas expression of the genes encoding wild-type or S46A HPr had no effect on this enzyme activity. When the promoterless lacZ gene was put under the control of the gnt promoter and was subsequently incorporated into the amyE gene on the B. subtilis chromosome, expression of beta-galactosidase was inducible by gluconate and repressed by glucose. However, we observed no repression of beta-galactosidase activity in a strain carrying the ptsH1 mutation. Additionally, we investigated a ccpA mutant strain and observed that all of the enzymes which we found to be relieved from carbon catabolite repression in the ptsH1 mutant strain were also insensitive to catabolite repression in the ccpA mutant. Enzymes that were repressed in the ptsH1 mutant were also repressed in the ccpA mutant.

Publication Type: Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.;

8.  Biochemistry 1994 Dec 27; 51(33):15271-82.
Structural consequences of histidine phosphorylation: NMR characterization of the phosphohistidine form of histidine-containing protein from Bacillus subtilis and Escherichia coli.

Rajagopal P ,Waygood EB ,Klevit RE ,

Department of Biochemistry, University of Washington, Seattle 98195.

The bacterial phosphoenolpyruvate:sugar phosphotransferase system involves a series of reactions in which phosphoprotein intermediates are formed. Histidine-containing protein (HPr) is phosphorylated on the N delta 1 position of the imidazole ring of His15 by enzyme I and acts as a phosphoryl donor to the sugar-specific enzymes IIA. The structure of phosphorylated HPr from Bacillus subtilis, primarily, and from Escherichia coli has been studied by nuclear magnetic resonance (NMR) spectroscopy. Phosphorylation of His15 results in large downfield shifts in amide proton and nitrogen resonances for residues 16 and 17 but results in only modest or no shifts in other backbone resonances. The exchange rates of these two amide groups are decreased more than 10-fold upon phosphorylation. Analysis of the coupling constants 3JNH alpha revealed no significant changes throughout the protein, indicating that backbone phi dihedral angles do not change detectably. 3J alpha beta and 3JN beta patterns determined from P.E.COSY and HNHB spectra, respectively, revealed a change in one side chain, that of conserved Arg17. Analysis of NOESY spectra revealed a limited number of changes in NOEs involving protons in Ser12, His15, Arg71, and Pro18 in B. subtilis HPr. The NMR results indicate that the Arg17 side chain becomes limited in its conformational range in the phosphorylated protein, taking on a conformation that points its guanidinium group toward the phosphoryl group on His15. In addition, the tautomeric and ionization states of His15 have been determined using 15N and 31P NMR. At neutral pH, the imidazole is predominantly in the protonated form and the phosphoryl group is in the dianionic form in P-His15. Altogether, the results indicate that phosphorylation of His15 yields only a local effect on the protein's structure. The data are consistent with a small change in the disposition of the histidine side chain, allowing phosphoryl group oxygens to serve as hydrogen bond acceptors for the amide protons of residues Ala16 and Arg17, which constitute the first two residues of an alpha-helix. Thus, similar to many proteins that bind phosphoryl moieties noncovalently, the phosphoryl group in P-His15-HPr is situated to allow for a favorable electrostatic interaction at the N-terminal end of an alpha-helix.

Publication Type: Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.;

9.  Structure 1994 Dec 15; 12(2):1203-16.
Refined structures of the active Ser83-->Cys and impaired Ser46-->Asp histidine-containing phosphocarrier proteins.

Liao DI ,Herzberg O ,

Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville 20850.

BACKGROUND: The histidine-containing phosphocarrier protein (HPr) functions in the bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS). His15 on HPr accepts a phosphoryl group from Enzyme I and transfers it to the Enzyme IIA domain of a sugar-specific PTS permease. In addition, HPrs from Gram-positive bacteria undergo phosphorylation on a serine residue, Ser46, which inhibits phosphorylation at His15 and sugar transport. The questions to be addressed at the molecular level are: what is the mechanism of each of the phosphoryl transfers and what conformational transitions are associated with each event? RESULTS: Thus, the crystal structures of the mutants Ser83-->Cys HPr (fully active protein) and Ser46-->Asp HPr (impaired protein which mimics Ser46 approximately P HPr) from Bacillus subtilis have been determined at 2 A resolution. They have been crystallized from high-salt and low-salt solutions respectively, and in two different space groups. Analysis of the two crystal forms reveals some significant differences but these do not alter the overall fold of the protein. In each structure, the side chain of His15 caps the following helix. Two alternative side-chain conformations of Arg17 are observed; it either forms an ion pair with a sulfate ion, presumably resembling the phosphorylated state of the protein (high-salt crystal) or with Glu84 (low-salt crystal). The main-chain conformation in the region of residue 46 is the same in the two crystal forms, with both Ser46 and Asp46 capping the following helix. CONCLUSIONS: The analysis suggests that phosphorylation of either His15 or Ser46 is not associated with main-chain conformational transitions. Rather, the protein is poised to accept the respective phosphoryl group with minor adjustments to side chains. The inhibitory effect of phosphorylation on Ser46 is attributed to the altered surface electrostatics, which impairs protein-protein interaction.

Publication Type: Research Support, U.S. Gov't, Non-P.H.S.;

10.  Biochemistry 1989 Dec 26; 26(28):9908-12.
Common structural changes accompany the functional inactivation of HPr by seryl phosphorylation or by serine to aspartate substitution.

Wittekind M ,Reizer J ,Deutscher J ,Saier MH ,Klevit RE ,

Department of Biochemistry, University of Washington, Seattle 98195.

Although many proteins are known to be regulated via reversible phosphorylation, little is known about the mechanism by which the covalent modification of seryl, threonyl, or tyrosyl residues alters the activities of the target systems. To address this question, modified versions of Bacillus subtilus HPr, a protein component of the bacterial phosphotransferase system, have been studied by 1H NMR spectroscopy. Phosphorylation at Ser46 or a Ser to Asp substitution at this position inactivates HPr [Reizer, J., Sutrina, S. L., Saier, M. H., Stewart, G. C., Peterkofsky, A., & Reddy, P. (1989) EMBO J. 8, 2111-2120]. Two-dimensional spectra of these two modified proteins display nearly identical proton chemical shifts that differ significantly from those observed in the spectra of the unphosphorylated, wild-type protein and of functionally active HPr mutants. The results demonstrate that the functional inactivation of HPr brought about by the serine to aspartate mutation is accompanied by the same structural changes that occur when HPr is phosphorylated at Ser46.

Publication Type: Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.;

11.  Mol Microbiol 1989 Jan ; 1(3):103-12.
Phosphoenolpyruvate:sugar phosphotransferase system of Bacillus subtilis: nucleotide sequence of ptsX, ptsH and the 5'-end of ptsI and evidence for a ptsHI operon.

Gonzy-Tréboul G ,Zagorec M ,Rain-Guion MC ,Steinmetz M ,

Institut Jacques Monod, Université Paris VII, France.

The nucleotide sequence of a 1689bp fragment of the Bacillus subtilis locus containing ptsX (a crr-like gene), ptsH (coding for HPr), and the 5'-end of ptsI (coding for Enzyme I) was determined. The deduced amino acid sequences of ptsH and the N-terminal part of ptsI were compared to those of Streptococcus faecalis and Escherichia coli. Transcription fusion demonstrated that ptsHI constitutes an operon. An open reading frame overlapping the main part of ptsH in the opposite sense was shown to be expressed in vivo, using protein fusions with beta-galactosidase. The deduced amino acid sequence of ptsX showed significant homology with that of Salmonella typhimurium glucose-specific Enzyme III. ptsX was preceded by an open reading frame whose amino acid sequence showed strong homology with the C-terminal part of E. coli Enzyme IIGlc.

Publication Type: Comparative Study; Research Support, Non-U.S. Gov't;

12.  Biochemistry 1990 Aug 7; 31(29):7191-200.
Sequence-specific 1H NMR resonance assignments of Bacillus subtilis HPr: use of spectra obtained from mutants to resolve spectral overlap.

Wittekind M ,Reizer J ,Klevit RE ,

Department of Biochemistry, University of Washington, Seattle 98195.

On the basis of an analysis of two-dimensional 1H NMR spectra, the complete sequence-specific 1H NMR assignments are presented for the phosphocarrier protein HPr from the Gram-positive bacterium Bacillus subtilis. During the assignment procedure, extensive use was made of spectra obtained from point mutants of HPr in order to resolve spectral overlap and to provide verification of assignments. Regions of regular secondary structure were identified by characteristic patterns of sequential backbone proton NOEs and slowly exchanging amide protons. B. subtilis HPr contains four beta-strands that form a single antiparallel beta-sheet and two well-defined alpha-helices. There are two stretches of extended backbone structure, one of which contains the active site His15. The overall fold of the protein is very similar to that of Escherichia coli HPr determined by NMR studies [Klevit, R. E., & Waygood, E. B. (1986) Biochemistry 25, 7774-7781].

Publication Type: Comparative Study; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.;

13.  J Mol Biol 1990 Jan 5; 1(211):1-4.
Transcription from the rha operon psr promoter.

Tobin JF ,Schleif RF ,

Department of Biochemistry, Brandeis University, Waltham, MA 02254.

S1 nuclease mapping experiments performed with RNA extracted from cell lines that were unable to metabolize L-rhamnose demonstrated that L-rhamnose and not a metabolite was the inducer of the L-rhamnose operons of Escherichia coli. In vitro transcription studies showed that purified RhaR activates transcription from the psr promoter in the presence of L-rhamnose. In the absence of L-rhamnose, RhaR binds to the psr promoter but does not activate transcription until L-rhamnose is added.


14.  Proc Natl Acad Sci U S A 1992 Mar 15; 6(89):2499-503.
Structure of the histidine-containing phosphocarrier protein HPr from Bacillus subtilis at 2.0-A resolution.

Herzberg O ,Reddy P ,Sutrina S ,Saier MH Jr,Reizer J ,Kapadia G ,

Maryland Biotechnology Institute, University of Maryland, Rockville.

The crystal structure of the histidine-containing phosphocarrier protein (HPr) of the phosphoenolpyruvate:sugar phosphotransferase system (PTS) from Bacillus subtilis has been determined at 2.0-A resolution and refined to a crystallographic residual error R-factor of 0.150. The secondary-structure folding topology of the molecule is that of an open-face beta-sandwich formed by four antiparallel beta-strands packed against three alpha-helices. The active-site histidine, His-15, caps the N terminus of the first helix, suggesting that the helix dipole plays a role in stabilizing the phosphorylated state of the histidine. A sulfate anion located between His-15 and the neighboring Arg-17 has been identified in the electron-density map. Association of this negatively charged species with the two key catalytic residues implies that the crystal structure resembles the phosphorylated state of the protein. A model of the phosphorylated form of the molecule is proposed, in which the negatively charged phosphoryl group interacts with two main-chain nitrogen atoms of the following helix and with the guanidinium group of Arg-17. It is also proposed that the phosphoryl transfer from HPr to the IIA domain of the glucose permease involves Arg-17 switching between two salt bridges: one with the phosphorylated histidyl of HPr and the other with two aspartyl residues associated with the active site of the IIA domain of glucose permease, which are accessible upon complex formation.

Publication Type: Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.;

15.  Mol Microbiol 1992 Jun ; 12(6):1579-81.
Amino acid sequences of several Bacillus subtilis proteins modified by apparent guanylylation.

Mitchell C ,Morris PW ,Vary JC ,

Department of Biochemistry, University of Illinois, Chicago 60612.

Bacillus subtilis cell extracts, prepared at different times during growth, contained several proteins that were apparently guanylylated in vitro with [alpha-32P]-GTP. Four of the proteins were partially purified and the N-terminal amino acid sequences (13 to 20 residues) were determined. One sequence had 84% identity to Bacillus stearothermophilus triosephosphate isomerase, two were 100% identical to the predicted sequences of the B. subtilis ptsI and ptsH genes while no identity was found for the fourth sequence. This apparent guanylylation occurred with proteins involved in glucose metabolism, although the significance is unknown.


16.  Protein Sci 1992 Oct ; 10(1):1363-76.
Solution structure of the phosphocarrier protein HPr from Bacillus subtilis by two-dimensional NMR spectroscopy.

Wittekind M ,Rajagopal P ,Branchini BR ,Reizer J ,Saier MH Jr,Klevit RE ,

Department of Biochemistry, University of Washington, Seattle 98195.

The solution structure of the phosphocarrier protein, HPr, from Bacillus subtilis has been determined by analysis of two-dimensional (2D) NMR spectra acquired for the unphosphorylated form of the protein. Inverse-detected 2D (1H-15N) heteronuclear multiple quantum correlation nuclear Overhauser effect (HMQC NOESY) and homonuclear Hartmann-Hahn (HOHAHA) spectra utilizing 15N assignments (reported here) as well as previously published 1H assignments were used to identify cross-peaks that are not resolved in 2D homonuclear 1H spectra. Distance constraints derived from NOESY cross-peaks, hydrogen-bonding patterns derived from 1H-2H exchange experiments, and dihedral angle constraints derived from analysis of coupling constants were used for structure calculations using the variable target function algorithm, DIANA. The calculated models were refined by dynamical simulated annealing using the program X-PLOR. The resulting family of structures has a mean backbone rmsd of 0.63 A (N, C alpha, C', O atoms), excluding the segments containing residues 45-59 and 84-88. The structure is comprised of a four-stranded antiparallel beta-sheet with two antiparallel alpha-helices on one side of the sheet. The active-site His 15 residue serves as the N-cap of alpha-helix A, with its N delta 1 atom pointed toward the solvent to accept the phosphoryl group during the phosphotransfer reaction with enzyme I. The existence of a hydrogen bond between the side-chain oxygen atom of Tyr 37 and the amide proton of Ala 56 is suggested, which may account for the observed stabilization of the region that includes the beta-turn comprised of residues 37-40. If the beta alpha beta beta alpha beta (alpha) folding topology of HPr is considered with the peptide chain polarity reversed, the protein fold is identical to that described for another group of beta alpha beta beta alpha beta proteins that include acylphosphatase and the RNA-binding domains of the U1 snRNP A and hnRNP C proteins.

Publication Type: Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.;

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