1
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Nys K, Pfanzagl V, Roefs J, Obinger C, Van Doorslaer S. In Vitro Heme Coordination of a Dye-Decolorizing Peroxidase-The Interplay of Key Amino Acids, pH, Buffer and Glycerol. Int J Mol Sci 2021; 22:ijms22189849. [PMID: 34576013 PMCID: PMC8468270 DOI: 10.3390/ijms22189849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/31/2021] [Accepted: 09/03/2021] [Indexed: 11/17/2022] Open
Abstract
Dye-decolorizing peroxidases (DyPs) have gained interest for their ability to oxidize anthraquinone-derived dyes and lignin model compounds. Spectroscopic techniques, such as electron paramagnetic resonance and optical absorption spectroscopy, provide main tools to study how the enzymatic function is linked to the heme-pocket architecture, provided the experimental conditions are carefully chosen. Here, these techniques are used to investigate the effect of active site perturbations on the structure of ferric P-class DyP from Klebsiella pneumoniae (KpDyP) and three variants of the main distal residues (D143A, R232A and D143A/R232A). Arg-232 is found to be important for maintaining the heme distal architecture and essential to facilitate an alkaline transition. The latter is promoted in absence of Asp-143. Furthermore, the non-innocent effect of the buffer choice and addition of the cryoprotectant glycerol is shown. However, while unavoidable or indiscriminate experimental conditions are pitfalls, careful comparison of the effects of different exogenous molecules on the electronic structure and spin state of the heme iron contains information about the inherent flexibility of the heme pocket. The interplay between structural flexibility, key amino acids, pH, temperature, buffer and glycerol during in vitro spectroscopic studies is discussed with respect to the poor peroxidase activity of bacterial P-class DyPs.
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Affiliation(s)
- Kevin Nys
- BIMEF Laboratory, Department of Chemistry, University of Antwerp, 2610 Antwerp, Belgium; (K.N.); (J.R.)
| | - Vera Pfanzagl
- Division of Biochemistry, Department of Chemistry, BOKU—University of Natural Resources and Life Sciences, 1190 Vienna, Austria; (V.P.); (C.O.)
| | - Jeroen Roefs
- BIMEF Laboratory, Department of Chemistry, University of Antwerp, 2610 Antwerp, Belgium; (K.N.); (J.R.)
| | - Christian Obinger
- Division of Biochemistry, Department of Chemistry, BOKU—University of Natural Resources and Life Sciences, 1190 Vienna, Austria; (V.P.); (C.O.)
| | - Sabine Van Doorslaer
- BIMEF Laboratory, Department of Chemistry, University of Antwerp, 2610 Antwerp, Belgium; (K.N.); (J.R.)
- Correspondence: ; Tel.: +32-3-265-2461
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2
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Dybas J, Chiura T, Marzec KM, Mak PJ. Probing Heme Active Sites of Hemoglobin in Functional Red Blood Cells Using Resonance Raman Spectroscopy. J Phys Chem B 2021; 125:3556-3565. [PMID: 33787265 PMCID: PMC8154613 DOI: 10.1021/acs.jpcb.1c01199] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
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The UV–vis absorption, Raman
imaging, and resonance Raman
(rR) spectroscopy methods were employed to study cyanohemoglobin (HbCN)
adducts inside living functional red blood cells (RBCs). The cyanide
ligands are especially optically sensitive probes of the active site
environment of heme proteins. The rR studies of HbCN and its isotopic
analogues (13CN–, C15N–, and 13C15N–), as well as a careful deconvolution of spectral data, revealed
that the ν(Fe–CN) stretching, δ(Fe–CN) bending,
and ν(C≡N) stretching modes occur at 454, 382, and 2123
cm–1, respectively. Interestingly, while the ν(Fe–CN)
modes exhibit the same frequencies in both the isolated and RBC-enclosed
hemoglobin molecules, small frequency differences are observed in
the δ(Fe–CN) bending modes and the values of their isotopic
shifts. These studies show that even though the overall tilted conformation
of the Fe–C≡N fragment in the isolated HbCN is preserved
in the HbCN enclosed within living cells, there is a small difference
in the degree of distortion of the Fe–C≡N fragment.
The slight changes in the ligand geometry can be reasonably attributed
to the high ordering and tight packing of Hb molecules inside RBCs.
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Affiliation(s)
- Jakub Dybas
- Chemistry Department, Saint Louis University, 3501 Laclede Avenue, Saint Louis 63103, Missouri, United States.,Jagiellonian Centre for Experimental Therapeutics (JCET), Jagiellonian University, 14 Bobrzyńskiego Str., Krakow 30-348, Poland
| | - Tapiwa Chiura
- Chemistry Department, Saint Louis University, 3501 Laclede Avenue, Saint Louis 63103, Missouri, United States
| | - Katarzyna M Marzec
- Jagiellonian Centre for Experimental Therapeutics (JCET), Jagiellonian University, 14 Bobrzyńskiego Str., Krakow 30-348, Poland
| | - Piotr J Mak
- Chemistry Department, Saint Louis University, 3501 Laclede Avenue, Saint Louis 63103, Missouri, United States
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3
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Control of distal lysine coordination in a monomeric hemoglobin: A role for heme peripheral interactions. J Inorg Biochem 2021; 219:111437. [PMID: 33892380 DOI: 10.1016/j.jinorgbio.2021.111437] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 03/20/2021] [Accepted: 03/20/2021] [Indexed: 12/25/2022]
Abstract
THB1 is a monomeric truncated hemoglobin (TrHb) found in the cytoplasm of the green alga Chlamydomonas reinhardtii. The canonical heme coordination scheme in hemoglobins is a proximal histidine ligand and an open distal site. In THB1, the latter site is occupied by Lys53, which is likely to facilitate Fe(II)/Fe(III) redox cycling but hinders dioxygen binding, two features inherent to the NO dioxygenase activity of the protein. TrHb surveys show that a lysine at a position aligning with Lys53 is an insufficient determinant of coordination, and in this study, we sought to identify factors controlling lysine affinity for the heme iron. We solved the "Lys-off" X-ray structure of THB1, represented by the cyanide adduct of the Fe(III) protein, and hypothesized that interactions that differ between the known "Lys-on" structure and the Lys-off structure participate in the control of Lys53 affinity for the heme iron. We applied an experimental approach (site-directed mutagenesis, heme modification, pH titrations in the Fe(III) and Fe(II) states) and a computational approach (MD simulations in the Fe(II) state) to assess the role of heme propionate-protein interactions, distal helix capping, and the composition of the distal pocket. All THB1 modifications resulted in a weakening of lysine affinity and affected the coupling between Lys53 proton binding and heme redox potential. The results supported the importance of specific heme peripheral interactions for the pH stability of iron coordination and the ability of the protein to undergo redox reactions.
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4
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Schmidt D, Serra I, Mlynek G, Pfanzagl V, Hofbauer S, Furtmüller PG, Djinović-Carugo K, Van Doorslaer S, Obinger C. Arresting the Catalytic Arginine in Chlorite Dismutases: Impact on Heme Coordination, Thermal Stability, and Catalysis. Biochemistry 2021; 60:621-634. [PMID: 33586945 PMCID: PMC7931450 DOI: 10.1021/acs.biochem.0c00910] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Chlorite dismutases
(Clds) are heme b-containing
oxidoreductases that can decompose chlorite to chloride and molecular
oxygen. They are divided in two clades that differ in oligomerization,
subunit architecture, and the hydrogen-bonding network of the distal
catalytic arginine, which is proposed to switch between two conformations
during turnover. To understand the impact of the conformational dynamics
of this basic amino acid on heme coordination, structure, and catalysis,
Cld from Cyanothece sp. PCC7425 was used as a model
enzyme. As typical for a clade 2 Cld, its distal arginine 127 is hydrogen-bonded
to glutamine 74. The latter has been exchanged with either glutamate
(Q74E) to arrest R127 in a salt bridge or valine (Q74V) that mirrors
the setting in clade 1 Clds. We present the X-ray crystal structures
of Q74V and Q74E and demonstrate the pH-induced changes in the environment
and coordination of the heme iron by ultraviolet–visible, circular
dichroism, and electron paramagnetic resonance spectroscopies as well
as differential scanning calorimetry. The conformational dynamics
of R127 is shown to have a significant role in heme coordination during
the alkaline transition and in the thermal stability of the heme cavity,
whereas its impact on the catalytic efficiency of chlorite degradation
is relatively small. The findings are discussed with respect to (i)
the flexible loop connecting the N-terminal and C-terminal ferredoxin-like
domains, which differs in clade 1 and clade 2 Clds and carries Q74
in clade 2 proteins, and (ii) the proposed role(s) of the arginine
in catalysis.
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Affiliation(s)
- Daniel Schmidt
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Ilenia Serra
- BIMEF Laboratory, Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium
| | - Georg Mlynek
- Department of Structural and Computational Biology, Max Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria
| | - Vera Pfanzagl
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Stefan Hofbauer
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Paul G Furtmüller
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Kristina Djinović-Carugo
- Department of Structural and Computational Biology, Max Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria.,Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 5, SI-1000 Ljubljana, Slovenia
| | - Sabine Van Doorslaer
- BIMEF Laboratory, Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium
| | - Christian Obinger
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
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5
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Foglia NO, Bari SE, Estrin DA. In Silico Insight into the Reductive Nitrosylation of Ferric Hemeproteins. Inorg Chem 2020; 59:3631-3641. [DOI: 10.1021/acs.inorgchem.9b03198] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Nicolás O. Foglia
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Quı́mica de los Materiales, Medio Ambiente y Energı́a, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Quı́mica Inorgánica, Analı́tica y Quı́mica Fı́sica, Buenos Aires, Argentina
| | - Sara E. Bari
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Quı́mica de los Materiales, Medio Ambiente y Energı́a, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina
| | - Darío A. Estrin
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Quı́mica de los Materiales, Medio Ambiente y Energı́a, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Quı́mica Inorgánica, Analı́tica y Quı́mica Fı́sica, Buenos Aires, Argentina
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6
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Giordano D, Boubeta FM, di Prisco G, Estrin DA, Smulevich G, Viappiani C, Verde C. Conformational Flexibility Drives Cold Adaptation in Pseudoalteromonas haloplanktis TAC125 Globins. Antioxid Redox Signal 2020; 32:396-411. [PMID: 31578873 DOI: 10.1089/ars.2019.7887] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Significance: Temperature is one of the most important drivers in shaping protein adaptations. Many biochemical and physiological processes are influenced by temperature. Proteins and enzymes from organisms living at low temperature are less stable in comparison to high-temperature adapted proteins. The lower stability is generally due to greater conformational flexibility. Recent Advances: Adaptive changes in the structure of cold-adapted proteins may occur at subunit interfaces, distant from the active site, thus producing energy changes associated with conformational transitions transmitted to the active site by allosteric modulation, valid also for monomeric proteins in which tertiary structural changes may play an essential role. Critical Issues: Despite efforts, the current experimental and computational methods still fail to produce general principles on protein evolution, since many changes are protein and species dependent. Environmental constraints or other biological cellular signals may override the ancestral information included in the structure of the protein, thus introducing inaccuracy in estimates and predictions on the evolutionary adaptations of proteins in response to cold adaptation. Future Directions: In this review, we describe the studies and approaches used to investigate stability and flexibility in the cold-adapted globins of the Antarctic marine bacterium Pseudoalteromonas haloplanktis TAC125. In fact, future research directions will be prescient on more detailed investigation of cold-adapted proteins and the role of fluctuations between different conformational states.
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Affiliation(s)
- Daniela Giordano
- Institute of Biosciences and BioResources (IBBR), CNR, Napoli, Italy.,Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Fernando Martín Boubeta
- Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Guido di Prisco
- Institute of Biosciences and BioResources (IBBR), CNR, Napoli, Italy
| | - Dario A Estrin
- Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | | | - Cristiano Viappiani
- Department of Mathematical, Physical and Computer Sciences, University of Parma, Parma, Italy
| | - Cinzia Verde
- Institute of Biosciences and BioResources (IBBR), CNR, Napoli, Italy.,Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
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7
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Boubeta FM, Bieza SA, Bringas M, Palermo JC, Boechi L, Estrin DA, Bari SE. Hemeproteins as Targets for Sulfide Species. Antioxid Redox Signal 2020; 32:247-257. [PMID: 31530164 DOI: 10.1089/ars.2019.7878] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Significance: Sulfides are endogenous and ubiquitous signaling species that share the hemeproteins as biochemical targets with O2, nitric oxide, and carbon monoxide. The description of the binding mechanisms is mandatory to anticipate the biochemical relevance of the interaction. Recent Advances: The binding of sulfide to ferric hemeproteins has been described in more than 40 systems, including native proteins, mutants, and model systems. Mechanisms of sulfide binding to ferric hemeproteins have been examined by a combination of kinetic and computational experiments. The distal control of the association process, dissected into the migration of the ligand to the active site and the binding event, reveals that neutral hydrogen sulfide (H2S) reaches the active site and is the predominant binding ligand, while the HS- is excluded by the protein matrix. Experiments with model compounds, devoid of a protein scaffold, reveal that both H2S and HS- can bind the ferric heme if accessing the site. A critical role of the proximal ligand in the prevention of the metal-centered reduction has been experimentally assessed. For metmyoglobin and methemoglobin, the coordination of sulfide leads to noncanonical functions: sulfide storage and its oxidative detoxification have been evidenced under physiological and excess sulfide concentrations, respectively. Critical Issues: The bound species is suggested to predominate in the monoprotonated form, although spectroscopic evidence is pending. Future Directions: A description of the role of hemeproteins as biochemical targets for inorganic sulfide requires understanding the reactivity of bound sulfide, for example: the metal-centered reduction, the reaction with excess sulfide, oxidants, or other gasotransmitters, among other biomolecules.
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Affiliation(s)
- Fernando Martín Boubeta
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía. (INQUIMAE) CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Silvina Andrea Bieza
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía. (INQUIMAE) CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Mauro Bringas
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía. (INQUIMAE) CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina.,Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Juan Cruz Palermo
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía. (INQUIMAE) CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Leonardo Boechi
- Facultad de Ciencias Exactas y Naturales, Instituto de Cálculo, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Darío Ariel Estrin
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía. (INQUIMAE) CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina.,Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Sara Elizabeth Bari
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía. (INQUIMAE) CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina
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8
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Feis A, Howes BD, Milazzo L, Coppola D, Smulevich G. Structural determinants of ligand binding in truncated hemoglobins: Resonance Raman spectroscopy of the native states and their carbon monoxide and hydroxide complexes. Biopolymers 2018; 109:e23114. [DOI: 10.1002/bip.23114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 02/20/2018] [Accepted: 02/21/2018] [Indexed: 02/06/2023]
Affiliation(s)
- Alessandro Feis
- Dipartimento di Chimica “Ugo Schiff,”; Università di Firenze, Via della Lastruccia 3-13; Sesto Fiorentino 50019 Italy
| | - Barry D. Howes
- Dipartimento di Chimica “Ugo Schiff,”; Università di Firenze, Via della Lastruccia 3-13; Sesto Fiorentino 50019 Italy
| | - Lisa Milazzo
- Dipartimento di Chimica “Ugo Schiff,”; Università di Firenze, Via della Lastruccia 3-13; Sesto Fiorentino 50019 Italy
| | - Daniela Coppola
- Dipartimento di Scienze bio-agroalimentari del CNR (DiSBA-CNR), CNR, Via Pietro Castellino 111; Naples I-80131 Italy
| | - Giulietta Smulevich
- Dipartimento di Chimica “Ugo Schiff,”; Università di Firenze, Via della Lastruccia 3-13; Sesto Fiorentino 50019 Italy
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9
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Geeraerts Z, Celis AI, Mayfield JA, Lorenz M, Rodgers KR, DuBois JL, Lukat-Rodgers GS. Distinguishing Active Site Characteristics of Chlorite Dismutases with Their Cyanide Complexes. Biochemistry 2018; 57:1501-1516. [PMID: 29406727 PMCID: PMC5849076 DOI: 10.1021/acs.biochem.7b01278] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
O2-evolving chlorite dismutases (Clds) efficiently convert chlorite (ClO2-) to O2 and Cl-. Dechloromonas aromatica Cld ( DaCld) is a highly active chlorite-decomposing homopentameric enzyme, typical of Clds found in perchlorate- and chlorate-respiring bacteria. The Gram-negative, human pathogen Klebsiella pneumoniae contains a homodimeric Cld ( KpCld) that also decomposes ClO2-, albeit with an activity 10-fold lower and a turnover number lower than those of DaCld. The interactions between the distal pocket and heme ligand of the DaCld and KpCld active sites have been probed via kinetic, thermodynamic, and spectroscopic behaviors of their cyanide complexes for insight into active site characteristics that are deterministic for chlorite decomposition. At 4.7 × 10-9 M, the KD for the KpCld-CN- complex is 2 orders of magnitude smaller than that of DaCld-CN- and indicates an affinity for CN- that is greater than that of most heme proteins. The difference in CN- affinity between Kp- and DaClds is predominantly due to differences in koff. The kinetics of binding of cyanide to DaCld, DaCld(R183Q), and KpCld between pH 4 and 8.5 corroborate the importance of distal Arg183 and a p Ka of ∼7 in stabilizing complexes of anionic ligands, including the substrate. The Fe-C stretching and FeCN bending modes of the DaCld-CN- (νFe-C, 441 cm-1; δFeCN, 396 cm-1) and KpCld-CN- (νFe-C, 441 cm-1; δFeCN, 356 cm-1) complexes reveal differences in their FeCN angle, which suggest different distal pocket interactions with their bound cyanide. Conformational differences in their catalytic sites are also reported by the single ferrous KpCld carbonyl complex, which is in contrast to the two conformers observed for DaCld-CO.
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Affiliation(s)
- Zachary Geeraerts
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58102, USA
| | - Arianna I. Celis
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Jeffery A. Mayfield
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Megan Lorenz
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58102, USA
| | - Kenton R. Rodgers
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58102, USA
| | - Jennifer L. DuBois
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Gudrun S. Lukat-Rodgers
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58102, USA
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10
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Van Doorslaer S, Cuypers B. Electron paramagnetic resonance of globin proteins – a successful match between spectroscopic development and protein research. Mol Phys 2017. [DOI: 10.1080/00268976.2017.1392629] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
| | - Bert Cuypers
- Department of Physics, University of Antwerp, Antwerp, Belgium
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11
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Geeraerts Z, Rodgers KR, DuBois JL, Lukat-Rodgers GS. Active Sites of O 2-Evolving Chlorite Dismutases Probed by Halides and Hydroxides and New Iron-Ligand Vibrational Correlations. Biochemistry 2017; 56:4509-4524. [PMID: 28758386 DOI: 10.1021/acs.biochem.7b00572] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
O2-evolving chlorite dismutases (Clds) fall into two subfamilies, which efficiently convert ClO2- to O2 and Cl-. The Cld from Dechloromonas aromatica (DaCld) represents the chlorite-decomposing homopentameric enzymes found in perchlorate- and chlorate-respiring bacteria. The Cld from the Gram-negative human pathogen Klebsiella pneumoniae (KpCld) is representative of the second subfamily, comprising homodimeric enzymes having truncated N-termini. Here steric and nonbonding properties of the DaCld and KpCld active sites have been probed via kinetic, thermodynamic, and spectroscopic behaviors of their fluorides, chlorides, and hydroxides. Cooperative binding of Cl- to KpCld drives formation of a hexacoordinate, high-spin aqua heme, whereas DaCld remains pentacoordinate and high-spin under analogous conditions. Fluoride coordinates to the heme iron in KpCld and DaCld, exhibiting ν(FeIII-F) bands at 385 and 390 cm-1, respectively. Correlation of these frequencies with their CT1 energies reveals strong H-bond donation to the F- ligand, indicating that atoms directly coordinated to heme iron are accessible to distal H-bond donation. New vibrational frequency correlations between either ν(FeIII-F) or ν(FeIII-OH) and ν(FeII-His) of Clds and other heme proteins are reported. These correlations orthogonalize proximal and distal effects on the bonding between iron and exogenous π-donor ligands. The axial Fe-X vibrations and the relationships between them illuminate both similarities and differences in the H-bonding and electrostatic properties of the distal and proximal heme environments in pentameric and dimeric Clds. Moreover, they provide general insight into the structural basis of reactivity toward substrates in heme-dependent enzymes and their mechanistic intermediates, especially those containing the ferryl moiety.
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Affiliation(s)
- Zachary Geeraerts
- Department of Chemistry and Biochemistry, North Dakota State University , Fargo, North Dakota 58102, United States
| | - Kenton R Rodgers
- Department of Chemistry and Biochemistry, North Dakota State University , Fargo, North Dakota 58102, United States
| | - Jennifer L DuBois
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59715, United States
| | - Gudrun S Lukat-Rodgers
- Department of Chemistry and Biochemistry, North Dakota State University , Fargo, North Dakota 58102, United States
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12
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Mittra K, Sengupta K, Singha A, Bandyopadhyay S, Chatterjee S, Rana A, Samanta S, Dey A. Second sphere control of spin state: Differential tuning of axial ligand bonds in ferric porphyrin complexes by hydrogen bonding. J Inorg Biochem 2016; 155:82-91. [DOI: 10.1016/j.jinorgbio.2015.11.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Revised: 10/02/2015] [Accepted: 11/10/2015] [Indexed: 11/16/2022]
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13
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Bustamante JP, Radusky L, Boechi L, Estrin DA, ten Have A, Martí MA. Evolutionary and Functional Relationships in the Truncated Hemoglobin Family. PLoS Comput Biol 2016; 12:e1004701. [PMID: 26788940 PMCID: PMC4720485 DOI: 10.1371/journal.pcbi.1004701] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 12/10/2015] [Indexed: 12/21/2022] Open
Abstract
Predicting function from sequence is an important goal in current biological research, and although, broad functional assignment is possible when a protein is assigned to a family, predicting functional specificity with accuracy is not straightforward. If function is provided by key structural properties and the relevant properties can be computed using the sequence as the starting point, it should in principle be possible to predict function in detail. The truncated hemoglobin family presents an interesting benchmark study due to their ubiquity, sequence diversity in the context of a conserved fold and the number of characterized members. Their functions are tightly related to O2 affinity and reactivity, as determined by the association and dissociation rate constants, both of which can be predicted and analyzed using in-silico based tools. In the present work we have applied a strategy, which combines homology modeling with molecular based energy calculations, to predict and analyze function of all known truncated hemoglobins in an evolutionary context. Our results show that truncated hemoglobins present conserved family features, but that its structure is flexible enough to allow the switch from high to low affinity in a few evolutionary steps. Most proteins display moderate to high oxygen affinities and multiple ligand migration paths, which, besides some minor trends, show heterogeneous distributions throughout the phylogenetic tree, again suggesting fast functional adaptation. Our data not only deepens our comprehension of the structural basis governing ligand affinity, but they also highlight some interesting functional evolutionary trends.
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Affiliation(s)
- Juan P. Bustamante
- Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Leandro Radusky
- Departamento de Química Biológica e Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Leonardo Boechi
- Instituto de Cálculo, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Darío A. Estrin
- Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Arjen ten Have
- Instituto de Investigación Biológica, CONICET, Universidad Nacional de Mar del Plata. Buenos Aires, Argentina
| | - Marcelo A. Martí
- Instituto de Cálculo, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
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14
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Tilleman L, Germani F, De Henau S, Helbo S, Desmet F, Berghmans H, Van Doorslaer S, Hoogewijs D, Schoofs L, Braeckman BP, Moens L, Fago A, Dewilde S. A globin domain in a neuronal transmembrane receptor of Caenorhabditis elegans and Ascaris suum: molecular modeling and functional properties. J Biol Chem 2015; 290:10336-52. [PMID: 25666609 DOI: 10.1074/jbc.m114.576520] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Indexed: 01/12/2023] Open
Abstract
We report the structural and biochemical characterization of GLB-33, a putative neuropeptide receptor that is exclusively expressed in the nervous system of the nematode Caenorhabditis elegans. This unique chimeric protein is composed of a 7-transmembrane domain (7TM), GLB-33 7TM, typical of a G-protein-coupled receptor, and of a globin domain (GD), GLB-33 GD. Comprehensive sequence similarity searches in the genome of the parasitic nematode, Ascaris suum, revealed a chimeric protein that is similar to a Phe-Met-Arg-Phe-amide neuropeptide receptor. The three-dimensional structures of the separate domains of both species and of the full-length proteins were modeled. The 7TM domains of both proteins appeared very similar, but the globin domain of the A. suum receptor surprisingly seemed to lack several helices, suggesting a novel truncated globin fold. The globin domain of C. elegans GLB-33, however, was very similar to a genuine myoglobin-type molecule. Spectroscopic analysis of the recombinant GLB-33 GD showed that the heme is pentacoordinate when ferrous and in the hydroxide-ligated form when ferric, even at neutral pH. Flash-photolysis experiments showed overall fast biphasic CO rebinding kinetics. In its ferrous deoxy form, GLB-33 GD is capable of reversibly binding O2 with a very high affinity and of reducing nitrite to nitric oxide faster than other globins. Collectively, these properties suggest that the globin domain of GLB-33 may serve as a highly sensitive oxygen sensor and/or as a nitrite reductase. Both properties are potentially able to modulate the neuropeptide sensitivity of the neuronal transmembrane receptor.
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Affiliation(s)
| | | | - Sasha De Henau
- the Department of Biology, Ghent University, 9000 Ghent, Belgium
| | - Signe Helbo
- the Department of Bioscience, Aarhus University, 8000 Aarhus, Denmark
| | - Filip Desmet
- Physics, University of Antwerp, 2610 Antwerp, Belgium
| | | | | | - David Hoogewijs
- the Institute of Physiology and Zürich Center for Integrative Human Physiology, University of Zürich, 8006 Zürich, Switzerland, Institute of Physiology, University of Duisburg-Essen, D-45147 Essen, Germany, and
| | - Liliane Schoofs
- the Functional Genomics and Proteomics Group, KU Leuven, 3000 Leuven, Belgium
| | - Bart P Braeckman
- the Department of Biology, Ghent University, 9000 Ghent, Belgium
| | - Luc Moens
- From the Departments of Biomedical Sciences and
| | - Angela Fago
- the Department of Bioscience, Aarhus University, 8000 Aarhus, Denmark
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15
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Boron I, Bustamante JP, Davidge KS, Singh S, Bowman LAH, Tinajero-Trejo M, Carballal S, Radi R, Poole RK, Dikshit K, Estrin DA, Marti MA, Boechi L. Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules. F1000Res 2015; 4:22. [PMID: 26478812 PMCID: PMC4591903 DOI: 10.12688/f1000research.5921.2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/20/2015] [Indexed: 11/23/2022] Open
Abstract
Mycobacterium tuberculosis, the causative agent of human tuberculosis, has two proteins belonging to the truncated hemoglobin (trHb) family. Mt-trHbN presents well-defined internal hydrophobic tunnels that allow O 2 and •NO to migrate easily from the solvent to the active site, whereas Mt-trHbO possesses tunnels interrupted by a few bulky residues, particularly a tryptophan at position G8. Differential ligand migration rates allow Mt-trHbN to detoxify •NO, a crucial step for pathogen survival once under attack by the immune system, much more efficiently than Mt-trHbO. In order to investigate the differences between these proteins, we performed experimental kinetic measurements, •NO decomposition, as well as molecular dynamics simulations of the wild type Mt-trHbN and two mutants, VG8F and VG8W. These mutations affect both the tunnels accessibility as well as the affinity of distal site water molecules, thus modifying the ligand access to the iron. We found that a single mutation allows Mt-trHbN to acquire ligand migration rates comparable to those observed for Mt-trHbO, confirming that ligand migration is regulated by the internal tunnel architecture as well as by water molecules stabilized in the active site.
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Affiliation(s)
- Ignacio Boron
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina
| | - Juan Pablo Bustamante
- Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina
| | - Kelly S Davidge
- Centre for Biomolecular Sciences, The University of Nottingham, Nottingham, NG7 2RD, UK
| | - Sandip Singh
- Institute of Microbial Technology, CSIR, Chandigarh, 160036, India
| | - Lesley AH Bowman
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Mariana Tinajero-Trejo
- Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, S10 2TN, UK
| | - Sebastián Carballal
- Departamento de Bioquímica and Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Montevideo, 11100, Uruguay
| | - Rafael Radi
- Departamento de Bioquímica and Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Montevideo, 11100, Uruguay
| | - Robert K Poole
- Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, S10 2TN, UK
| | - Kanak Dikshit
- Institute of Microbial Technology, CSIR, Chandigarh, 160036, India
| | - Dario A Estrin
- Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina
| | - Marcelo A Marti
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina
| | - Leonardo Boechi
- Instituto de Cálculo, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina
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16
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Boron I, Bustamante JP, Davidge KS, Singh S, Bowman LAH, Tinajero-Trejo M, Carballal S, Radi R, Poole RK, Dikshit K, Estrin DA, Marti MA, Boechi L. Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules. F1000Res 2015; 4:22. [PMID: 26478812 PMCID: PMC4591903 DOI: 10.12688/f1000research.5921.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/19/2015] [Indexed: 06/04/2024] Open
Abstract
Mycobacterium tuberculosis, the causative agent of human tuberculosis, has two proteins belonging to the truncated hemoglobin (trHb) family. Mt-trHbN presents well-defined internal hydrophobic tunnels that allow O 2 and (•)NO to migrate easily from the solvent to the active site, whereas Mt-trHbO possesses tunnels that are partially blocked by a few bulky residues, particularly a tryptophan at position G8. Differential ligand migration rates allow Mt-trHbN to detoxify (•)NO, a crucial step for pathogen survival once under attack by the immune system, much more efficiently than Mt-trHbO. In order to investigate the differences between these proteins, we performed experimental kinetic measurements, (•)NO decomposition, as well as molecular dynamics simulations of the wild type Mt-trHbN and two mutants, VG8F and VG8W. These mutations introduce modifications in both tunnel topologies and affect the incoming ligand capacity to displace retained water molecules at the active site. We found that a single mutation allows Mt-trHbN to acquire ligand migration rates comparable to those observed for Mt-trHbO, confirming that ligand migration is regulated by the internal tunnel architecture as well as by water molecules stabilized in the active site.
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Affiliation(s)
- Ignacio Boron
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina
| | - Juan Pablo Bustamante
- Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina
| | - Kelly S Davidge
- Centre for Biomolecular Sciences, The University of Nottingham, Nottingham, NG7 2RD, UK
| | - Sandip Singh
- Institute of Microbial Technology, CSIR, Chandigarh, 160036, India
| | - Lesley AH Bowman
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Mariana Tinajero-Trejo
- Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, S10 2TN, UK
| | - Sebastián Carballal
- Departamento de Bioquímica and Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Montevideo, 11100, Uruguay
| | - Rafael Radi
- Departamento de Bioquímica and Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Montevideo, 11100, Uruguay
| | - Robert K Poole
- Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, S10 2TN, UK
| | - Kanak Dikshit
- Institute of Microbial Technology, CSIR, Chandigarh, 160036, India
| | - Dario A Estrin
- Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina
| | - Marcelo A Marti
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina
| | - Leonardo Boechi
- Instituto de Cálculo, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina
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17
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Howes BD, Boechi L, Boffi A, Estrin DE, Smulevich G. Bridging Theory and Experiment to Address Structural Properties of Truncated Haemoglobins: Insights from Thermobifida fusca HbO. Adv Microb Physiol 2015; 67:85-126. [PMID: 26616516 DOI: 10.1016/bs.ampbs.2015.08.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In this chapter, we will discuss the paradigmatic case of Thermobifida fusca (Tf-trHb) HbO in its ferrous and ferric states and its behaviour towards a battery of possible ligands. This choice was dictated by the fact that it has been one of the most extensively studied truncated haemoglobins, both in terms of spectroscopic and molecular dynamics studies. Tf-trHb typifies the structural properties of group II trHbs, as the active site is characterized by a highly polar distal environment in which TrpG8, TyrCD1, and TyrB10 provide three potential H-bond donors in the distal cavity capable of stabilizing the incoming ligands. The role of these residues in key topological positions, and their interplay with the iron-bound ligands, has been addressed in studies carried out on the CO, F(-), OH(-), CN(-), and HS(-) adducts formed with the wild-type protein and a combinatorial set of mutants, in which the distal polar residues, TrpG8, TyrCD1, and TyrB10, have been singly, doubly, or triply replaced by a Phe residue. In this context, such a complete analysis provides an excellent benchmark for the investigation of the relationship between protein structure and function, allowing one to translate physicochemical properties of the active site into the observed functional behaviour. Tf-trHb will be compared with other members of the group II trHbs and, more generally, with members of the other trHb subgroups.
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Affiliation(s)
- Barry D Howes
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze, Sesto Fiorentino, Italy
| | - Leonardo Boechi
- Instituto de Cálculo, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
| | - Alberto Boffi
- Dipartimento di Scienze Biochimiche, Università "Sapienza", Rome, Italy
| | - Dario E Estrin
- Departamento de Química Inorgánica, Analítica y Química Física and Inquimae-Conicet, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Giulietta Smulevich
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze, Sesto Fiorentino, Italy.
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18
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Nicoletti FP, Bustamante JP, Droghetti E, Howes BD, Fittipaldi M, Bonamore A, Baiocco P, Feis A, Boffi A, Estrin DA, Smulevich G. Interplay of the H-Bond Donor–Acceptor Role of the Distal Residues in Hydroxyl Ligand Stabilization of Thermobifida fusca Truncated Hemoglobin. Biochemistry 2014; 53:8021-30. [DOI: 10.1021/bi501132a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Francesco P. Nicoletti
- Dipartimento
di Chimica “Ugo Schiff”, Università di Firenze, Via della
Lastruccia 3-13, I-50019 Sesto Fiorentino (FI), Italy
| | | | - Enrica Droghetti
- Dipartimento
di Chimica “Ugo Schiff”, Università di Firenze, Via della
Lastruccia 3-13, I-50019 Sesto Fiorentino (FI), Italy
| | - Barry D. Howes
- Dipartimento
di Chimica “Ugo Schiff”, Università di Firenze, Via della
Lastruccia 3-13, I-50019 Sesto Fiorentino (FI), Italy
| | - Maria Fittipaldi
- INSTM
and Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, via Sansone 1, I-50019 Sesto Fiorentino, Italy
| | - Alessandra Bonamore
- Institute
Pasteur, Fondazione Cenci Bolognetti, Department of Biochemical Sciences
and CNR, Institute of Molecular Biology and Pathology, University of Rome “La Sapienza”, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Paola Baiocco
- Center of
Life Nano Sciences, Italian Institute of Technology, Viale Regina
Elena 291, I-00161 Rome, Italy
| | - Alessandro Feis
- Dipartimento
di Chimica “Ugo Schiff”, Università di Firenze, Via della
Lastruccia 3-13, I-50019 Sesto Fiorentino (FI), Italy
| | - Alberto Boffi
- Institute
Pasteur, Fondazione Cenci Bolognetti, Department of Biochemical Sciences
and CNR, Institute of Molecular Biology and Pathology, University of Rome “La Sapienza”, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | | | - Giulietta Smulevich
- Dipartimento
di Chimica “Ugo Schiff”, Università di Firenze, Via della
Lastruccia 3-13, I-50019 Sesto Fiorentino (FI), Italy
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19
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Patrizi B, Lapini A, Di Donato M, Marcelli A, Lima M, Righini R, Foggi P, Baiocco P, Bonamore A, Boffi A. Role of local structure and dynamics of small ligand migration in proteins: a study of a mutated truncated hemoprotein from Thermobifida fusca by time resolved MIR spectroscopy. J Phys Chem B 2014; 118:9209-17. [PMID: 25019316 DOI: 10.1021/jp504499b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Carbon monoxide recombination dynamics in a mutant of the truncated hemoglobin from Thermobida fusca (3F-Tf-trHb) has been analyzed by means of ultrafast Visible-pump/MidIR-probe spectroscopy and compared with that of the wild-type protein. In 3F-Tf-trHb, three topologically relevant amino acids, responsible for the ligand stabilization through the formation of a H-bond network (TyrB10 TyrCD1 and TrpG8), have been replaced by Phe residues. X-ray diffraction data show that Phe residues in positions B10 and G8 maintain the same rotameric arrangements as Tyr and Trp in the wild-type protein, while Phe in position CD1 displays significant rotameric heterogeneity. Photodissociation of the ligand has been induced by exciting the sample with 550 nm pump pulses and the CO rebinding has been monitored in two mid-IR regions respectively corresponding to the ν(CO) stretching vibration of the iron-bound CO (1880-1980 cm(-1)) and of the dissociated free CO (2050-2200 cm(-1)). In both the mutant and wild-type protein, a significant amount of geminate CO rebinding is observed on a subnanosecond time scale. Despite the absence of the distal pocket hydrogen-bonding network, the kinetics of geminate rebinding in 3F-Tf-trHb is very similar to the wild-type, showing how the reactivity of dissociated CO toward the heme is primarily regulated by the effective volume and flexibility of the distal pocket and by caging effects exerted on the free CO on the analyzed time scale.
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Affiliation(s)
- Barbara Patrizi
- LENS (European Laboratory for Nonlinear Spectroscopy) Via N. Carrara 1, Sesto Fiorentino, Florence 50019, Italy
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20
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Molecular basis of thermal stability in truncated (2/2) hemoglobins. Biochim Biophys Acta Gen Subj 2014; 1840:2281-8. [PMID: 24704259 DOI: 10.1016/j.bbagen.2014.03.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 03/14/2014] [Accepted: 03/25/2014] [Indexed: 11/23/2022]
Abstract
BACKGROUND Understanding the molecular mechanism through which proteins are functional at extreme high and low temperatures is one of the key issues in structural biology. To investigate this phenomenon, we have focused on two instructive truncated hemoglobins from Thermobifida fusca (Tf-trHbO) and Mycobacterium tuberculosis (Mt-trHbO); although the two proteins are structurally nearly identical, only the former is stable at high temperatures. METHODS We used molecular dynamics simulations at different temperatures as well as thermal melting profile measurements of both wild type proteins and two mutants designed to interchange the amino acid residue, either Pro or Gly, at E3 position. RESULTS The results show that the presence of a Pro at the E3 position is able to increase (by 8°) or decrease (by 4°) the melting temperature of Mt-trHbO and Tf-trHbO, respectively. We observed that the ProE3 alters the structure of the CD loop, making it more flexible. CONCLUSIONS This gain in flexibility allows the protein to concentrate its fluctuations in this single loop and avoid unfolding. The alternate conformations of the CD loop also favor the formation of more salt-bridge interactions, together augmenting the protein's thermostability. GENERAL SIGNIFICANCE These results indicate a clear structural and dynamical role of a key residue for thermal stability in truncated hemoglobins.
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21
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Bustamante JP, Abbruzzetti S, Marcelli A, Gauto D, Boechi L, Bonamore A, Boffi A, Bruno S, Feis A, Foggi P, Estrin DA, Viappiani C. Ligand uptake modulation by internal water molecules and hydrophobic cavities in hemoglobins. J Phys Chem B 2014; 118:1234-45. [PMID: 24410478 DOI: 10.1021/jp410724z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Internal water molecules play an active role in ligand uptake regulation, since displacement of retained water molecules from protein surfaces or cavities by incoming ligands can promote favorable or disfavorable effects over the global binding process. Detection of these water molecules by X-ray crystallography is difficult given their positional disorder and low occupancy. In this work, we employ a combination of molecular dynamics simulations and ligand rebinding over a broad time range to shed light into the role of water molecules in ligand migration and binding. Computational studies on the unliganded structure of the thermostable truncated hemoglobin from Thermobifida fusca (Tf-trHbO) show that a water molecule is in the vicinity of the iron heme, stabilized by WG8 with the assistance of YCD1, exerting a steric hindrance for binding of an exogenous ligand. Mutation of WG8 to F results in a significantly lower stabilization of this water molecule and in subtle dynamical structural changes that favor ligand binding, as observed experimentally. Water is absent from the fully hydrophobic distal cavity of the triple mutant YB10F-YCD1F-WG8F (3F), due to the lack of residues capable of stabilizing it nearby the heme. In agreement with these effects on the barriers for ligand rebinding, over 97% of the photodissociated ligands are rebound within a few nanoseconds in the 3F mutant case. Our results demonstrate the specific involvement of water molecules in shaping the energetic barriers for ligand migration and binding.
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Affiliation(s)
- Juan P Bustamante
- Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires , Buenos Aires, Argentina
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