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Neira JL, Palomino-Schätzlein M. Folding of the nascent polypeptide chain of a histidine phosphocarrier protein in vitro. Arch Biochem Biophys 2023; 736:109538. [PMID: 36738980 DOI: 10.1016/j.abb.2023.109538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/28/2023] [Accepted: 02/01/2023] [Indexed: 02/05/2023]
Abstract
The phosphotransferase system (PTS), a metabolic pathway formed by five proteins, modulates the use of sugars in bacteria. The second protein in the chain is the histidine phosphocarrier, HPr, with the binding site at His15. The HPr kinase/phosphorylase (HPrK/P), involved in the bacterial use of carbon sources, phosphorylates HPr at Ser46, and it binds at its binding site. The regulator of sigma D protein (Rsd) also binds to HPr at His15. We have designed fragments of HPr, growing from its N-terminus and containing the His15. In this work, we obtained three fragments, HPr38, HPr58 and HPr70, comprising the first thirty-eight, fifty-eight and seventy residues of HPr, respectively. All fragments were mainly disordered, with evidence of a weak native-like, helical population around the binding site, as shown by fluorescence, far-ultraviolet circular dichroism, size exclusion chromatography and nuclear magnetic resonance. Although HPr38, HPr58 and HPr70 were disordered, they could bind to: (i) the N-terminal domain of first protein of the PTS, EIN; (ii) Rsd; and, (iii) HPrK/P, as shown by fluorescence and biolayer interferometry (BLI). The association constants for each protein to any of the fragments were in the low micromolar range, within the same range than those measured in the binding of HPr to each protein. Then, although acquisition of stable, native-like secondary and tertiary structures occurred at the last residues of the polypeptide, the ability to bind protein partners happened much earlier in the growing chain. Binding was related to the presence of the native-like structure around His15.
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Affiliation(s)
- José L Neira
- IDIBE, Universidad Miguel Hernández, 03202, Elche, Alicante, Spain; Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), Joint Units IQFR-CSIC-BIFI and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50018, Zaragoza, Spain.
| | - Martina Palomino-Schätzlein
- ProtoQSAR SL, CEEI-Valencia, Parque Tecnológico de Valencia, Av. Benjamin Franklin 12 (Dep. 8), 46980, Paterna, Valencia, Spain
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2
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Residual Helicity at the Active Site of the Histidine Phosphocarrier, HPr, Modulates Binding Affinity to Its Natural Partners. Int J Mol Sci 2021; 22:ijms221910805. [PMID: 34639146 PMCID: PMC8509676 DOI: 10.3390/ijms221910805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/01/2021] [Accepted: 10/02/2021] [Indexed: 11/16/2022] Open
Abstract
The phosphoenolpyruvate-dependent phosphotransferase system (PTS) modulates the preferential use of sugars in bacteria. The first proteins in the cascade are common to all organisms (EI and HPr). The active site of HPr involves a histidine (His15) located immediately before the beginning of the first α-helix. The regulator of sigma D (Rsd) protein also binds to HPr. The region of HPr comprising residues Gly9-Ala30 (HPr9–30), involving the first α-helix (Ala16-Thr27) and the preceding active site loop, binds to both the N-terminal region of EI and intact Rsd. HPr9–30 is mainly disordered. We attempted to improve the affinity of HPr9–30 to both proteins by mutating its sequence to increase its helicity. We designed peptides that led to a marginally larger population in solution of the helical structure of HPr9–30. Molecular simulations also suggested a modest increment in the helical population of mutants, when compared to the wild-type. The mutants, however, were bound with a less favorable affinity than the wild-type to both the N-terminal of EI (EIN) or Rsd, as tested by isothermal titration calorimetry and fluorescence. Furthermore, mutants showed lower antibacterial properties against Staphylococcus aureus than the wild-type peptide. Therefore, we concluded that in HPr, a compromise between binding to its partners and residual structure at the active site must exist to carry out its function.
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3
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Neira JL, Palomino-Schätzlein M, Hurtado-Gómez E, Ortore MG, Falcó A. An N-terminal half fragment of the histidine phosphocarrier protein, HPr, is disordered but binds to HPr partners and shows antibacterial properties. Biochim Biophys Acta Gen Subj 2021; 1865:130015. [PMID: 34537288 DOI: 10.1016/j.bbagen.2021.130015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 08/26/2021] [Accepted: 09/15/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND The phosphotransferase system (PTS) modulates the preferential use of sugars in bacteria. It is formed by a protein cascade in which the first two proteins are general (namely enzyme I, EI, and the histidine phosphocarrier protein, HPr) and the others are sugar-specific permeases; the active site of HPr is His15. The HPr kinase/phosphorylase (HPrK/P), involved in the use of carbon sources in Gram-positive, phopshorylates HPr at a serine. The regulator of sigma D protein (Rsd) also binds to HPr. We are designing specific fragments of HPr, which can be used to interfere with those protein-protein interactions (PPIs), where the intact HPr intervenes. METHODS We obtained a fragment (HPr48) comprising the first forty-eight residues of HPr. HPr48 was disordered as shown by fluorescence, far-ultraviolet (UV) circular dichroism (CD), small angle X-ray scattering (SAXS) and nuclear magnetic resonance (NMR). RESULTS Secondary structure propensities, from the assigned backbone nuclei, further support the unfolded nature of the fragment. However, HPr48 was capable of binding to: (i) the N-terminal region of EI, EIN; (ii) the intact Rsd; and, (iii) HPrK/P, as shown by fluorescence, far-UV CD, NMR and biolayer interferometry (BLI). The association constants for each protein, as measured by fluorescence and BLI, were in the order of the low micromolar range, similar to those measured between the intact HPr and each of the other macromolecules. CONCLUSIONS Although HPr48 is forty-eight-residue long, it assisted antibiotics to exert antimicrobial activity. GENERAL SIGNIFICANCE HPr48 could be used as a lead compound in the development of new antibiotics, or, alternatively, to improve the efficiency of existing ones.
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Affiliation(s)
- José L Neira
- IDIBE, Universidad Miguel Hernández, 03202, Elche (Alicante), Spain; Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50018 Zaragoza, Spain.
| | | | | | - María G Ortore
- Dipartimento DiSVA, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy
| | - Alberto Falcó
- IDIBE, Universidad Miguel Hernández, 03202, Elche (Alicante), Spain.
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4
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Lindorff-Larsen K, Teilum K. Linking thermodynamics and measurements of protein stability. Protein Eng Des Sel 2021; 34:6173616. [PMID: 33724431 DOI: 10.1093/protein/gzab002] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/21/2020] [Accepted: 01/12/2021] [Indexed: 11/13/2022] Open
Abstract
We review the background, theory and general equations for the analysis of equilibrium protein unfolding experiments, focusing on denaturant and heat-induced unfolding. The primary focus is on the thermodynamics of reversible folding/unfolding transitions and the experimental methods that are available for extracting thermodynamic parameters. We highlight the importance of modelling both how the folding equilibrium depends on a perturbing variable such as temperature or denaturant concentration, and the importance of modelling the baselines in the experimental observables.
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Affiliation(s)
- Kresten Lindorff-Larsen
- Structural Biology and NMR Laboratory & Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Kaare Teilum
- Structural Biology and NMR Laboratory & Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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5
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Neira JL, Hornos F, Cozza C, Cámara-Artigas A, Abián O, Velázquez-Campoy A. The histidine phosphocarrier protein, HPr, binds to the highly thermostable regulator of sigma D protein, Rsd, and its isolated helical fragments. Arch Biochem Biophys 2017; 639:26-37. [PMID: 29288053 DOI: 10.1016/j.abb.2017.12.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 12/19/2017] [Accepted: 12/21/2017] [Indexed: 02/06/2023]
Abstract
The phosphotransferase system (PTS) controls the preferential use of sugars in bacteria and it is also involved in other processes, such as chemotaxis. It is formed by a protein cascade in which the first two proteins are general (namely, EI and HPr) and the others are sugar-specific permeases. The Rsd protein binds specifically to the RNA polymerase (RNAP) σ70 factor. We first characterized the conformational stability of Escherichia coli Rsd. And second, we delineated the binding regions of Streptomyces coelicolor, HPrsc, and E. coli Rsd, by using fragments derived from each protein. To that end, we used several biophysical probes, namely, fluorescence, CD, NMR, ITC and BLI. Rsd had a free energy of unfolding of 15 kcal mol-1 at 25 °C, and a thermal denaturation midpoint of 103 °C at pH 6.5. The affinity between Rsd and HPrsc was 2 μM. Interestingly enough, the isolated helical-peptides, comprising the third (RsdH3) and fourth (RsdH4) Rsd helices, also interacted with HPrsc in a specific manner, and with affinities similar to that of the whole Rsd. Moreover, the isolated peptide of HPrsc, HPr9-30, comprising the active site, His15, also was bound to intact Rsd with similar affinity. Therefore, binding between Rsd and HPrsc was modulated by the two helices H3 and H4 of Rsd, and the regions around the active site of HPrsc. This implies that specific fragments of Rsd and HPrsc can be used to interfere with other protein-protein interactions (PPIs) of each other protein.
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Affiliation(s)
- José L Neira
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche, Alicante, Spain; Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, Spain.
| | - Felipe Hornos
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche, Alicante, Spain
| | - Concetta Cozza
- Molecular Biophysics Laboratory, Department of Physics, University of Calabria, Rende, Italy
| | - Ana Cámara-Artigas
- Department of Chemistry and Physics, Research Centre CIAIMBITAL, University of Almería- ceiA3, Almería, Spain
| | - Olga Abián
- Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, Spain; Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain; Aragon Institute for Health Research (IIS Aragon), Zaragoza, Spain; Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain; Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain
| | - Adrián Velázquez-Campoy
- Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, Spain; Aragon Institute for Health Research (IIS Aragon), Zaragoza, Spain; Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain; Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain; Fundación ARAID, Diputación General de Aragón, Zaragoza, Spain.
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6
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Doménech R, Hernández-Cifre JG, Bacarizo J, Díez-Peña AI, Martínez-Rodríguez S, Cavasotto CN, de la Torre JG, Cámara-Artigás A, Velázquez-Campoy A, Neira JL. The histidine-phosphocarrier protein of the phosphoenolpyruvate: sugar phosphotransferase system of Bacillus sphaericus self-associates. PLoS One 2013; 8:e69307. [PMID: 23922699 PMCID: PMC3724859 DOI: 10.1371/journal.pone.0069307] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 06/12/2013] [Indexed: 12/12/2022] Open
Abstract
The phosphotransferase system (PTS) is involved in the use of carbon sources in bacteria. Bacillus sphaericus, a bacterium with the ability to produce insecticidal proteins, is unable to use hexoses and pentoses as the sole carbon source, but it has ptsHI genes encoding the two general proteins of the PTS: enzyme I (EI) and the histidine phosphocarrier (HPr). In this work, we describe the biophysical and structural properties of HPr from B. sphaericus, HPrbs, and its affinity towards EI of other species to find out whether there is inter-species binding. Conversely to what happens to other members of the HPr family, HPrbs forms several self-associated species. The conformational stability of the protein is low, and it unfolds irreversibly during heating. The protein binds to the N-terminal domain of EI from Streptomyces coelicolor, EINsc, with a higher affinity than that of the natural partner of EINsc, HPrsc. Modelling of the complex between EINsc and HPrbs suggests that binding occurs similarly to that observed in other HPr species. We discuss the functional implications of the oligomeric states of HPrbs for the glycolytic activity of B. sphaericus, as well as a strategy to inhibit binding between HPrsc and EINsc.
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Affiliation(s)
- Rosa Doménech
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche (Alicante), Spain
| | | | - Julio Bacarizo
- Departamento de Química y Física, Campus de Excelencia Internacional Agroalimentario, Universidad de Almería, Almería, Spain
| | - Ana I. Díez-Peña
- Departamento de Química Física, Universidad de Murcia, Murcia, Spain
| | - Sergio Martínez-Rodríguez
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche (Alicante), Spain
- Departamento de Química y Física, Campus de Excelencia Internacional Agroalimentario, Universidad de Almería, Almería, Spain
| | - Claudio N. Cavasotto
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET- Partner Institute of the Max Planck Society, Buenos Aires, Argentina
| | | | - Ana Cámara-Artigás
- Departamento de Química y Física, Campus de Excelencia Internacional Agroalimentario, Universidad de Almería, Almería, Spain
| | - Adrián Velázquez-Campoy
- Instituto de Biocomputación y Física de Sistemas Complejos, Unidad Asociada IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
- Fundación ARAID, Diputación General de Aragón, Zaragoza, Spain
- Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain
| | - José L. Neira
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche (Alicante), Spain
- Instituto de Biocomputación y Física de Sistemas Complejos, Unidad Asociada IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
- * E-mail:
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7
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Doménech R, Martínez-Gómez AI, Aguado-Llera D, Martínez-Rodríguez S, Clemente-Jiménez JM, Velázquez-Campoy A, Neira JL. Stability and binding of the phosphorylated species of the N-terminal domain of enzyme I and the histidine phosphocarrier protein from the Streptomyces coelicolor phosphoenolpyruvate:sugar phosphotransferase system. Arch Biochem Biophys 2012; 526:44-53. [PMID: 22809892 DOI: 10.1016/j.abb.2012.07.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 07/06/2012] [Accepted: 07/08/2012] [Indexed: 11/26/2022]
Abstract
The phosphotransferase system (PTS) is involved in the use of carbon sources in bacteria. It is formed by two general proteins: enzyme I (EI) and the histidine phosphocarrier (HPr), and various sugar-specific permeases. EI is formed by two domains, with the N-terminal domain (EIN) being responsible for the binding to HPr. In low-G+C Gram-positive bacteria, HPr becomes phosphorylated not only by phosphoenolpyruvate (PEP) at the active-site histidine, but also by ATP at a serine. In this work, we have characterized: (i) the stability and binding affinities between the active-site-histidine phosphorylated species of HPr and the EIN from Streptomyces coelicolor; and (ii) the stability and binding affinities of the species involving the phosphorylation at the regulatory serine of HPr(sc). Our results show that the phosphorylated active-site species of both proteins are less stable than the unphosphorylated counterparts. Conversely, the Hpr-S47D, which mimics phosphorylation at the regulatory serine, is more stable than wild-type HPr(sc) due to helical N-capping effects, as suggested by the modeled structure of the protein. Binding among the phosphorylated and unphosphorylated species is always entropically driven, but the affinity and the enthalpy vary widely.
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Affiliation(s)
- Rosa Doménech
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche (Alicante), Spain
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8
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Doménech R, Martínez-Rodríguez S, Velázquez-Campoy A, Neira JL. Peptides as Inhibitors of the First Phosphorylation Step of the Streptomyces coelicolor Phosphoenolpyruvate: Sugar Phosphotransferase System. Biochemistry 2012; 51:7393-402. [DOI: 10.1021/bi3010494] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Rosa Doménech
- Instituto de Biología
Molecular y Celular, Universidad Miguel Hernández, Elche (Alicante), Spain
| | - Sergio Martínez-Rodríguez
- Departamento de Química-Física,
Bioquímica y Química Inorgánica, Universidad de Almería, Almería, Spain
| | - Adrián Velázquez-Campoy
- Instituto de Biocomputación
y Física de Sistemas Complejos (BIFI), Unidad Asociada IQFR-BIFI, Universidad de Zaragoza, Zaragoza, Spain
- Fundación ARAID, Diputación General de Aragón, Zaragoza,
Spain
- Departamento de Bioquímica
y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain
| | - José L. Neira
- Instituto de Biología
Molecular y Celular, Universidad Miguel Hernández, Elche (Alicante), Spain
- Instituto de Biocomputación
y Física de Sistemas Complejos (BIFI), Unidad Asociada IQFR-BIFI, Universidad de Zaragoza, Zaragoza, Spain
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9
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Remmele RL, Zhang-van Enk J, Phan D, Yu L. Stabilization by Urea during Thermal Unfolding-Mediated Aggregation of Recombinant Human Interleukin-1 Receptor (Type II): Does Solvation Entropy Play a Role? J Phys Chem B 2012; 116:7240-51. [DOI: 10.1021/jp300398b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Richard L. Remmele
- MedImmune, 319 North Bernardo Avenue,
Mountain View, California 94043, United
States
| | - Jian Zhang-van Enk
- Amgen Inc., One Amgen Center Drive, Thousand Oaks, California
91320-1799, United
States
| | - Duke Phan
- Amgen Inc., 1201 Amgen Court West, Seattle, Washington 98119-3105,
United States
| | - Lei Yu
- Amgen Inc., One Amgen Center Drive, Thousand Oaks, California
91320-1799, United
States
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10
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Romero-Beviar M, Martínez-Rodríguez S, Prieto J, Goormaghtigh E, Ariz U, Martínez-Chantar MDLL, Gómez J, Neira JL. The N-terminal domain of the enzyme I is a monomeric well-folded protein with a low conformational stability and residual structure in the unfolded state. Protein Eng Des Sel 2010; 23:729-42. [PMID: 20630900 DOI: 10.1093/protein/gzq045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The bacterial phosphoenolpyruvate-dependent sugar phosphotransferase system is a multiprotein complex that phosphorylates and, concomitantly, transports carbohydrates across the membrane into the cell. The first protein of the cascade is a multidomain protein so-called enzyme I (EI). The N-terminal domain of EI from Streptomyces coelicolor, EIN(sc), responsible for the binding to the second protein in the cascade (the histidine phosphocarrier, HPr), was cloned and successfully expressed and purified. We have previously shown that EI(sc) binds to HPr(sc) with smaller affinity than other members of the EI and HPr families [Hurtado-Gómez et al. (2008) Biophys. J., 95, 1336-1348]. We think that the study of the isolated binding HPr(sc) domain, that is EIN(sc), could shed light on the small affinity value measured. Therefore, in this work we present a detailed description of the structural features of the EIN domain, as a first step towards a complete characterization of the molecular recognition process between the two proteins. We show that EIN(sc) is a folded protein, with alpha-helix and beta-sheet structures and also random-coil conformations, as shown by circular dichroism (CD), FTIR and NMR spectroscopies. The acquisition of secondary and tertiary structures, and the burial of hydrophobic regions, occurred concomitantly at acidic pHs, but at very low pH, the domain acquired a molten-globule conformation. The EIN(sc) protein was not very stable, with an apparent conformational free energy change upon unfolding, DeltaG, of 4.1 +/- 0.4 kcal mol(-1), which was pH independent in the range explored (from pH 6.0 to 8.5). The thermal denaturation midpoint, which was also pH invariant, was similar to that measured in the isolated intact EI(sc). Although EIN(sc) shows thermal- and chemical denaturations that seems to follow a two-state mechanism, there is evidence of residual structure in the chemical and thermally unfolded states, as indicated by differential scanning calorimetry and CD measurements.
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Affiliation(s)
- Manuel Romero-Beviar
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Avda. del Ferrocarril s/n, 03202 Alicante, Elche, Spain
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11
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Pethica BA. The thermodynamics of protein folding: a critique of widely used quasi-thermodynamic interpretations and a restatement based on the Gibbs–Duhem relation and consistent with the Phase Rule. Phys Chem Chem Phys 2010; 12:7445-56. [DOI: 10.1039/b920960c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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Defining the epitope region of a peptide from the Streptomyces coelicolor phosphoenolpyruvate:sugar phosphotransferase system able to bind to the enzyme I. Biophys J 2008; 95:1336-48. [PMID: 18456829 DOI: 10.1529/biophysj.107.126664] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The bacterial PEP:sugar PTS consists of a cascade of several proteins involved in the uptake and phosphorylation of carbohydrates, and in signal transduction pathways. Its uniqueness in bacteria makes the PTS a target for new antibacterial drugs. These drugs can be obtained from peptides or protein fragments able to interfere with the first reaction of the protein cascade: the phosphorylation of the HPr by the first enzyme, the so-called enzyme EI. To that end, we designed a peptide, HPr(9-30), spanning residues 9 to 30 of the intact HPr protein, containing the active site histidine (His-15) and the first alpha-helix of HPr of Streptomyces coelicolor, HPr(sc). By using fluorescence and circular dichroism, we first determined qualitatively that HPr(sc) and HPr(9-30) did bind to EI(sc), the enzyme EI from S. coelicolor. Then, we determined quantitatively the binding affinities of HPr(9-30) and HPr(sc) for EI(sc) by using ITC and STD-NMR. The STD-NMR experiments indicate that the epitope region of HPr(9-30) was formed by residues Leu-14, His-15, Ile-21, and Val-23. The binding reaction between EI(sc) and HPr(sc) is enthalpy driven and in other species is entropy driven; further, the affinity of HPr(sc) for EI(sc) was smaller than in other species. However, the affinity of HPr(9-30) for EI(sc) was only moderately lower than that of EI(sc) for HPr(sc), suggesting that this peptide could be considered a promising hit compound for designing new inhibitors against the PTS.
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13
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Thirumangalathu R, Krishnan S, Bondarenko P, Speed-Ricci M, Randolph TW, Carpenter JF, Brems DN. Oxidation of Methionine Residues in Recombinant Human Interleukin-1 Receptor Antagonist: Implications of Conformational Stability on Protein Oxidation Kinetics. Biochemistry 2007; 46:6213-24. [PMID: 17480058 DOI: 10.1021/bi700321g] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Oxidation of methionine residues is involved in several biochemical processes and in degradation of therapeutic proteins. The relationship between conformational stability and methionine oxidation in recombinant human interleukin-1 receptor antagonist (rhIL-1ra) was investigated to document how thermodynamics of unfolding affect methionine oxidation in proteins. Conformational stability of rhIL-1ra was monitored by equilibrium urea denaturation, and thermodynamic parameters of unfolding (DeltaGH2O, m, and Cm) were estimated at different temperatures. Methionine oxidation induced by hydrogen peroxide at varying temperatures was monitored during "coincubation" of rhIL-1ra with peptides mimicking specific regions of the reactive methionine residues in the protein. The coincubation study allowed estimation of oxidation rates in protein and peptide at each temperature from which normalized oxidation rate constants and activation energies were calculated. The rate constants for buried Met-11 in the protein were lower than for methionine in the peptide with an associated increase in activation energy. The rate constants and activation energy of solvent exposed methionines in protein and peptide were similar. The results showed that conformational stability, monitored using the Cm value, has an effect on oxidation rates of buried methionines. The rate constant of buried Met-11 correlated well with the Cm value but not DeltaGH2O. No correlation was observed for the oxidation rates of solvent-exposed methionines with any thermodynamic parameters of unfolding. The findings presented have implications in protein engineering, in design of accelerated stability studies for protein formulation development, and in understanding disease conditions involving protein oxidation.
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Affiliation(s)
- Renuka Thirumangalathu
- Center for Pharmaceutical Biotechnology, Department of Pharmaceutical Sciences, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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Hurtado-Gómez E, Fernández-Ballester G, Nothaft H, Gómez J, Titgemeyer F, Neira JL. Biophysical characterization of the enzyme I of the Streptomyces coelicolor phosphoenolpyruvate:sugar phosphotransferase system. Biophys J 2006; 90:4592-604. [PMID: 16581832 PMCID: PMC1471863 DOI: 10.1529/biophysj.105.076935] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The first protein in the bacterial phosphoenolpyruvate (PEP):sugar phosphotransferase system is the homodimeric 60-kDa enzyme I (EI), which autophosphorylates in the presence of PEP and Mg2+. The conformational stability and structure of the EI from Streptomyces coelicolor, EI(sc), were explored in the absence and in the presence of its effectors by using several biophysical probes (namely, fluorescence, far-ultraviolet circular dichroism, Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry) and computational approaches. The structure of EI(sc) was obtained by homology modeling of the isolated N- and C-terminal domains of other EI proteins. The experimental results indicate that at physiological pH, the dimeric EI(sc) had a well-folded structure; however, at low pH, EI(sc) showed a partially unfolded state with the features of a molten globule, as suggested by fluorescence, far-ultraviolet circular dichroism, FTIR, and 8-anilino-1-naphthalene-sulfonic acid binding. The thermal stability of EI(sc), in the absence of PEP and Mg2+, was maximal at pH 7. The presence of PEP and Mg2+ did not change substantially the secondary structure of the protein, as indicated by FTIR measurements. However, quenching experiments and proteolysis patterns suggest conformational changes in the presence of PEP; furthermore, the thermal stability of EI(sc) was modified depending on the effector added. Our approach suggests that thermodynamical analysis might reveal subtle conformational changes.
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Tang XC, Pikal MJ. The Effect of Stabilizers and Denaturants on the Cold Denaturation Temperatures of Proteins and Implications for Freeze-Drying. Pharm Res 2005; 22:1167-75. [PMID: 16028018 DOI: 10.1007/s11095-005-6035-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2004] [Accepted: 04/12/2005] [Indexed: 10/25/2022]
Abstract
PURPOSE The aim of the study is to investigate the effects of stabilizers and denaturants on the thermal and cold denaturation temperatures of selected proteins in systems of interest to freeze-drying. METHODS Beta-lactoglobulin and phosphoglycerate kinase (PGK) were chosen as model proteins. Protein thermal and cold denaturation temperatures were determined by both conventional and modulated differential scanning calorimetry and verified by tryptophan emission spectroscopy in selected systems. RESULTS The cold denaturation of beta-lactoglobulin was reversible, whereas the thermal denaturation was only reversible at high scanning rate (10 degrees C/min). The cold denaturation temperatures of beta-lactoglobulin decreased with an increase in protein concentration (self-stabilization). The cold denaturation temperature increased with increases in pH (from pH 2 to 7) with about 4.6 degrees C increase per unit pH change. All stabilizers studied (i.e., sucrose, trehalose and glycerol) increased the thermal denaturation temperature of the proteins studied and decreased the cold denaturation temperature. The effect of sucrose in decreasing the PGK cold denaturation temperature [40 degrees C per molar concentration increase (40 degrees C/M)] was of the same magnitude as for beta-lactoglobulin (36 degrees C/M). The effect of stabilizers on cold denaturation temperatures is much greater than the effect on thermal denaturation temperatures. With sucrose, the beta-lactoglobulin thermal denaturation temperature increases only about 5 degrees C from 0 to 2.7 M, whereas the decrease in cold denaturation temperature was more than 35 degrees C even at sucrose concentrations as low as 0.9 M. Denaturants (urea and guanidine hydrochloride) increased the cold denaturation temperatures of proteins and thereby destabilized protein; the magnitudes were 9 degrees C/M (urea on Tcd of beta-lactoglobulin) and 65 degrees C/M (guanidine hydrochloride on PGK) compared with literature data of 16 degrees C/M (guanidine hydrochloride on beta-lactoglobulin). The cold denaturation temperatures of beta-lactoglobulin and PGK extrapolated to zero concentration of denaturants were -14 and -26 degrees C, respectively. CONCLUSIONS The protein cold denaturation temperature was pH-, protein concentration-, and additive-dependent. Stabilizers, such as sugars and/or polyols, can stabilize both protein thermal and cold denaturation, whereas the denaturants destabilize protein cold denaturation. The stabilization effect on protein cold denaturation is much larger than on thermal denaturation, a result of great importance in protein freeze-drying.
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Affiliation(s)
- Xiaolin Charlie Tang
- School of Pharmacy, U-2092, University of Connecticut, 372 Fairfield Road, Storrs, Connecticut 06269-2092, USA
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Hurtado-Gómez E, Barrera FN, Neira JL. Structure and conformational stability of the enzyme I of Streptomyces coelicolor explored by FTIR and circular dichroism. Biophys Chem 2004; 115:229-33. [PMID: 15752610 DOI: 10.1016/j.bpc.2004.12.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2004] [Revised: 11/05/2004] [Accepted: 12/10/2004] [Indexed: 10/26/2022]
Abstract
The bacterial phosphoenolpyruvate (PEP): sugar phosphotransferase system (PTS), formed by a cascade of several proteins, couples the translocation and phosphorylation of specific sugars across cell membranes. The structure and thermal stability of the first protein (enzyme I, EI) of the PTS in Streptomyces coelicolor is studied by using far-UV circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR) at pH 7.0. The deconvolution of FTIR spectra indicates that the protein is mainly composed by a 35% of alpha-helical structure and 30% of beta-sheet. The thermal denaturation curves, as followed by both techniques, show only a midpoint at 330 K. This thermal denaturation behaviour is different to that observed in other members of the EI family.
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Affiliation(s)
- Estefanía Hurtado-Gómez
- Instituto de Biología Molecular y Celular, Edificio Torregaitán, Universidad Miguel Hernández, Avda. del Ferrocarril s/n, 03202, Elche, Alicante, Spain
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