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Berry RE, Muthu D, Yang F, Walker FA. NMR studies of the dynamics of high-spin nitrophorins: comparative studies of NP4 and NP2 at close to physiological pH. Biochemistry 2015; 54:221-39. [PMID: 25486224 PMCID: PMC4303294 DOI: 10.1021/bi501305a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
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The
β-barrel nitrophorin (NP) heme proteins are found in
the saliva of the blood-sucking insect Rhodnius prolixus, which synthesizes and stores nitric oxide (NO) in the salivary
glands. NO is bound to iron of the NPs and is released by dilution
and an increase in pH when the insect spits its saliva into the tissues
of a victim, to aid in obtaining a blood meal. In the adult insect,
there are four nitrophorins, NP1–NP4, which have sequence similarities
in two pairs, NP1 and NP4 (90% identical) and NP2 and NP3 (80% identical).
The available crystal structures of NP4 have been used to propose
that pH-dependent changes in the conformation of two loops between
adjacent β-strands at the front opening of the protein, the
A–B and G–H loops, determine the rate of NO release.
At pH 7.3, NP4 releases NO 17 times faster than NP2 does. In this
work, the aqua complexes of NP4 and NP2 have been investigated by
nuclear magnetic resonance (NMR) relaxation measurements to probe
the pico- to nanosecond and micro- to millisecond time scale motions
at two pH values, 6.5 and 7.3. It is found that NP4-OH2 is fairly rigid and only residues in the loop regions show dynamics
at pH 6.5; at pH 7.3, much more dynamics of the loops and most of
the β-strands are observed while the α-helices remain
fairly rigid. In comparison, NP2-OH2 shows much less dynamics,
albeit somewhat more than that of the previously reported NP2-NO complex
[Muthu, D., Berry, R. E., Zhang, H., and Walker, F. A. (2013) Biochemistry 52, 7910–7925]. The reasons for this
major difference between NP4 and NP2 are discussed.
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Affiliation(s)
- Robert E Berry
- Department of Chemistry and Biochemistry, The University of Arizona , 1306 East University Boulevard, Tucson, Arizona 85721-0041, United States
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Pond MP, Majumdar A, Lecomte JTJ. Influence of heme post-translational modification and distal ligation on the backbone dynamics of a monomeric hemoglobin. Biochemistry 2012; 51:5733-47. [PMID: 22775272 DOI: 10.1021/bi300624a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The cyanobacterium Synechococcus sp. PCC 7002 uses a hemoglobin of the truncated lineage (GlbN) in the detoxification of reactive species generated in the assimilation of nitrate. In view of a sensing or enzymatic role, several states of GlbN are of interest with respect to its structure-activity relationship. Nuclear magnetic resonance spectroscopy was applied to compare the structure and backbone dynamics of six GlbN forms differing in their oxidation state [Fe(II) or Fe(III)], distal ligand to the iron (histidine, carbon monoxide, or cyanide), or heme post-translational modification (b heme or covalently attached heme). Structural properties were assessed with pseudocontact shift calculations. (15)N relaxation data were analyzed by reduced spectral density mapping (picosecond to nanosecond motions) and by inspection of elevated R(2) values (microsecond to millisecond motions). On the picosecond to nanosecond time scale, GlbN exhibited little flexibility and was unresponsive to the differences among the various forms. Regions of slightly higher mobility were the CE turn, the EF loop, and the H-H' kink. In contrast, fluctuations on the microsecond to millisecond time scale depended on the form. Cyanide binding to the ferric state did not enhance motions, whereas reduction to the ferrous bis-histidine state resulted in elevated R(2) values for several amides. This response was attributed, at least in part, to a weakening of the distal histidine coordination. Carbon monoxide binding quenched some of these fluctuations. The results emphasized the role of the distal ligand in dictating backbone flexibility and illustrated the multiple ways in which motions are controlled by the hemoglobin fold.
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Affiliation(s)
- Matthew P Pond
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
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Affiliation(s)
- LUCIA BANCI
- Dipartimento di Chimica and CERM, University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy
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Hass MAS, Keizers PHJ, Blok A, Hiruma Y, Ubbink M. Validation of a lanthanide tag for the analysis of protein dynamics by paramagnetic NMR spectroscopy. J Am Chem Soc 2010; 132:9952-3. [PMID: 20586489 DOI: 10.1021/ja909508r] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Paramagnetic lanthanide tags potentially can enhance the effects of microsecond to millisecond dynamics in proteins on NMR signals and provide structural information on lowly populated states encoded in the pseudocontact shifts. We have investigated the microsecond to millisecond mobility of a two-point attached lanthanide tag, CLaNP-5, using paramagnetic (1)H CPMG relaxation dispersion methods. CLaNP-5 loaded with Lu(3+), Yb(3+), or Tm(3+) was attached to three sites on the surface of two proteins, pseudoazurin and cytochrome c. The paramagnetic center causes large relaxation dispersion effects for two attachment sites, suggesting that local dynamics of the protein at the attachment site causes mobility of the paramagnetic center. At one site the relaxation dispersions are small and limited to the immediate environment of the tag. It is concluded that paramagnetic relaxation dispersion could represent a sensitive method to probe protein dynamics. However, the selection of a rigid attachment site is of critical importance.
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Affiliation(s)
- Mathias A S Hass
- Leiden University, Institute of Chemistry, Gorlaeus Laboratories, P.O. Box 9502, 2300 RA Leiden, The Netherlands
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Kamerzell TJ, Russell Middaugh C. The Complex Inter-Relationships Between Protein Flexibility and Stability. J Pharm Sci 2008; 97:3494-517. [DOI: 10.1002/jps.21269] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Wang L, Cowley AB, Benson DR. Enhancing the thermal stability of mitochondrial cytochrome b5 by introducing a structural motif characteristic of the less stable microsomal isoform. Protein Eng Des Sel 2007; 20:511-20. [PMID: 17962223 DOI: 10.1093/protein/gzm053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Outer mitochondrial membrane cytochrome b5 (OM b5) is the most thermostable cytochrome b5 isoform presently known. Herein, we show that OM b5 thermal stability is substantially enhanced by swapping an apparently invariant motif in its heme-independent folding core with the corresponding motif characteristic of its less stable evolutionary relative, microsomal cytochrome b5 (Mc b5). The motif swap involved replacing two residues, Arg15 with His and Glu20 with Ser, thereby introducing a Glu11-His15-Ser20 H-bonding triad on the protein surface along with a His15/Trp22 pi-stacking interaction. The ferric and ferrous forms of the OM b5 R15H/E20S double mutant have thermal denaturation midpoints (Tm values) of approximately 93 degrees C and approximately 104 degrees C, respectively. A 15 degrees C increase in apoprotein Tm plays a key role in the holoprotein thermal stability enhancement, and is achieved by one of the most common natural mechanisms for stabilization of thermophilic versus mesophilic proteins: raising the unfolding free energy along the entire stability curve.
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Affiliation(s)
- Lijun Wang
- Department of Chemistry, University of Kansas, Lawrence, KS 66045, USA
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Arnesano F, Banci L, Bertini I, Capozzi F, Ciofi-Baffoni S, Ciurli S, Luchinat C, Mangani S, Rosato A, Turano P, Viezzoli MS. An Italian contribution to structural genomics: Understanding metalloproteins. Coord Chem Rev 2006. [DOI: 10.1016/j.ccr.2006.01.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Giachetti A, La Penna GL, Perico A, Banci L. Modeling the backbone dynamics of reduced and oxidized solvated rat microsomal cytochrome b5. Biophys J 2005; 87:498-512. [PMID: 15240483 PMCID: PMC1304371 DOI: 10.1529/biophysj.103.036657] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In this article, a description of the statistics and dynamics of cytochrome b(5) in both reduced and oxidized forms is given. Results of molecular dynamics computer simulations in the explicit solvent have been combined with mode-coupling diffusion models including and neglecting the molecule-solvent correlations. R(1) and R(1 rho) nuclear magnetic relaxation parameters of (15)N in the protein backbone have been calculated and compared with experiments. Slight changes in charge density in the heme upon oxidation produces a cascade of changes in charge distributions from heme propionates up to charged residues approximately 1.5 nm from Fe. These changes in charge distributions modify the molecular surface and the water shell surrounding the protein. The statistical changes upon oxidation can be included in diffusive models that physically explain the upper and lower limits of R(1 rho) relaxation parameters at high off-resonance fields.
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Affiliation(s)
- Andrea Giachetti
- Magnetic Resonance Center, University of Florence, Florence, Italy
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Bertini I, Bryant DA, Ciurli S, Dikiy A, Fernández CO, Luchinat C, Safarov N, Vila AJ, Zhao J. Backbone dynamics of plastocyanin in both oxidation states. Solution structure of the reduced form and comparison with the oxidized state. J Biol Chem 2001; 276:47217-26. [PMID: 11509552 DOI: 10.1074/jbc.m100304200] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A model-free analysis based on (15)N R(1), (15)N R(2), and (15)N-(1)H nuclear Overhauser effects was performed on reduced (diamagnetic) and oxidized (paramagnetic) forms of plastocyanin from Synechocystis sp. PCC6803. The protein backbone is rigid, displaying a small degree of mobility in the sub-nanosecond time scale. The loops surrounding the copper ion, involved in physiological electron transfer, feature a higher extent of flexibility in the longer time scale in both redox states, as measured from D(2)O exchange of amide protons and from NH-H(2)O saturation transfer experiments. In contrast to the situation for other electron transfer proteins, no significant difference in the dynamic properties is found between the two redox forms. A solution structure was also determined for the reduced plastocyanin and compared with the solution structure of the oxidized form in order to assess possible structural changes related to the copper ion redox state. Within the attained resolution, the structure of the reduced plastocyanin is indistinguishable from that of the oxidized form, even though small chemical shift differences are observed. The present characterization provides information on both the structural and dynamic behavior of blue copper proteins in solution that is useful to understand further the role(s) of protein dynamics in electron transfer processes.
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Affiliation(s)
- I Bertini
- Magnetic Resonance Center and Department of Chemistry, University of Florence, Via L. Sacconi, 6-50019 Sesto Fiorentino, Italy
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Affiliation(s)
- I Bertini
- Magnetic Resonance Center (CERM), University of Florence, Florence 50019, Italy
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Barker PD, Bertini I, Del Conte R, Ferguson SJ, Hajieva P, Tomlinson E, Turano P, Viezzoli MS. A further clue to understanding the mobility of mitochondrial yeast cytochrome c: a (15)N T1rho investigation of the oxidized and reduced species. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:4468-76. [PMID: 11502207 DOI: 10.1046/j.1432-1327.2001.02369.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A new approach was developed to overproduce 15N-enriched yeast iso-1-cytochrome c in the periplasm of Escherichia coli in order to perform a study of the motions in the ms-micros time scale on the oxidized and reduced forms through rotating frame 15N relaxation rates and proton/deuterium exchange studies. It is confirmed that the reduced protein is rather rigid whereas the oxidized species is more flexible. The regions of the protein that display increased internal mobility upon oxidation are easily identified by the number of residues experiencing conformational equilibria and by their exchange rates. These data complement the information already available in the literature and provide a comprehensive picture of the mobility in the protein. In particular, oxidation mobilizes the loop containing Met80 and, through specific contacts, affects the mobility of helix 3 and possibly of helix 5, and of a section of protein connecting the heme propionates to helix 2. The relevance of internal motions to molecular recognition and to the early steps of the unfolding process of the oxidized species is also discussed. In agreement with the reported data, subnanosecond mobility is found to be less informative than the ms-micros with respect to redox dependent properties.
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Affiliation(s)
- P D Barker
- University Chemical Laboratory and Centre for Protein Engineering, University of Cambridge, UK
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Abstract
The methodological accessibility to solution structure and dynamic investigation of paramagnetic metallobiomolecules has afforded the ability to tackle the redox pairs of electron transfer proteins of which at least one is paramagnetic, to study the orientation effects of high magnetic fields on paramagnetic biomolecules, and finally to study the role of metal-based cofactors in protein folding and stability.
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Affiliation(s)
- I Bertini
- Department of Chemistry, University of Florence, Via Gino Capponi 7, 50121 Florence, Italy.
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Arnesano F, Banci L, Bertini I, Felli IC, Koulougliotis D. Solution structure of the B form of oxidized rat microsomal cytochrome b5 and backbone dynamics via 15N rotating-frame NMR-relaxation measurements. Biological implications. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 260:347-54. [PMID: 10095768 DOI: 10.1046/j.1432-1327.1999.00167.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cytochrome b5 in solution has two isomers (A and B) differing by a 180 degrees rotation of the protoporphyrin IX plane around the axis defined by the alpha and gamma meso protons. Homonuclear and heteronuclear NMR spectroscopy has been employed in order to solve the solution structure of the minor (B) form of the oxidized state of the protein and to probe its backbone dynamics in the microsecond--ms timescale in both oxidation states. A family of 40 conformers has been obtained using 1302 meaningful NOEs and 220 pseudocontact shifts and is characterized by high quality and good resolution (rmsd to the mean structure of 0.055 +/- 0.009 nm and 0.103 +/- 0.011 nm for backbone and heavy atoms, respectively). Extensive comparisons of the structural and dynamics changes associated with the A-to-B form interconversion for both oxidation states were subsequently performed. Propionate 6 experiences a redox-state-dependent reorientation as does propionate 7 in the A form. Significant insights are obtained into the role of the protein frame for efficient biological function and backbone mobility is proposed to be one of the factors that could control the reduction potential of the heme.
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Affiliation(s)
- F Arnesano
- Department of Chemistry, University of Florence, Italy
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