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Numoto N, Onoda S, Kawano Y, Okumura H, Baba S, Fukumori Y, Miki K, Ito N. Structures of oxygen dissociation intermediates of 400 kDa V2 hemoglobin provide coarse snapshots of the protein allostery. Biophys Physicobiol 2022; 19:1-10. [PMID: 35797404 PMCID: PMC9173864 DOI: 10.2142/biophysico.bppb-v19.0019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 05/09/2022] [Indexed: 12/01/2022] Open
Abstract
Ever since the historic discovery of the cooperative oxygenation of its multiple subunits, hemoglobin (Hb) has been among the most exhaustively studied allosteric proteins. However, the lack of structural information on the intermediates between oxygenated and deoxygenated forms prevents our detailed understanding of the molecular mechanism of its allostery. It has been difficult to prepare crystals of intact oxy-deoxy intermediates and to individually identify the oxygen saturation for each subunit. However, our recent crystallographic studies have demonstrated that giant Hbs from annelids are suitable for overcoming these problems and can provide abundant information on oxy-deoxy intermediate structures. Here, we report the crystal structures of oxy-deoxy intermediates of a 400 kDa Hb (V2Hb) from the annelid Lamellibrachia satsuma, following up on a series of previous studies of similar giant Hbs. Four intermediate structures had average oxygen saturations of 78%, 69%, 55%, and 26%, as determined by the occupancy refinement of the bound oxygen based on ambient temperature factors. The structures demonstrate that the cooperative oxygen dissociation is weaker, large ternary and quaternary changes are induced at a later stage of the oxygen dissociation process, and the ternary and quaternary changes are smaller with local perturbations. Nonetheless, the overall structural transition seemed to proceed in the manner of the MWC two-state model. Our crystallographic snapshots of the allosteric transition of V2Hb provide important experimental evidence for a more detailed understanding of the allostery of Hbs by extension of the Monod–Wyman–Changeux (MWC) model.
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Affiliation(s)
- Nobutaka Numoto
- Medical Research Institute, Tokyo Medical and Dental University (TMDU)
| | - Seiko Onoda
- Graduate School of Natural Science and Technology, Kanazawa University
| | | | - Hideo Okumura
- Structural Biology Division, Japan Synchrotron Radiation Research Institute
| | - Seiki Baba
- Structural Biology Division, Japan Synchrotron Radiation Research Institute
| | | | - Kunio Miki
- Graduate School of Science, Kyoto University
| | - Nobutoshi Ito
- Medical Research Institute, Tokyo Medical and Dental University (TMDU)
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Numoto N, Kawano Y, Okumura H, Baba S, Fukumori Y, Miki K, Ito N. Coarse snapshots of oxygen-dissociation intermediates of a giant hemoglobin elucidated by determining the oxygen saturation in individual subunits in the crystalline state. IUCRJ 2021; 8:954-962. [PMID: 34804547 PMCID: PMC8562662 DOI: 10.1107/s2052252521009386] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 09/08/2021] [Indexed: 06/13/2023]
Abstract
Cooperative oxygen binding of hemoglobin (Hb) has been studied for over half a century as a representative example of the allostericity of proteins. The most important problem remaining to be solved is the lack of structural information on the intermediates between the oxygenated and deoxygenated forms. In order to characterize the intermediate structures, it is necessary to obtain intermediate-state crystals, determine their oxygen saturations and then determine the oxygen saturations of each of their constituent subunits, all of which are challenging issues even now. Here, intermediate forms of the 400 kDa giant Hb from the tubeworm Oligobrachia mashikoi are reported. To overcome the above problems without any artificial modifications to the protein or prosthetic groups, intermediate crystals of the giant Hb were prepared from fully oxygenated crystals by a soaking method. The oxygen saturation of the crystals was measured by in situ observation with a microspectrophotometer using thin plate crystals processed by an ultraviolet laser to avoid saturation of absorption. The oxygen saturation of each subunit was determined by occupancy refinement of the bound oxygen based on ambient temperature factors. The obtained structures reveal the detailed relationship between the structural transition and oxygen dissociation. The dimer subassembly of the giant Hb shows strong correlation with the local structural changes at the heme pockets. Although some local ternary-structural changes occur in the early stages of the structural transition, the associated global ternary-structural and quaternary-structural changes might arise at about 50% oxygen saturation. The models based on coarse snapshots of the allosteric transition support the conventional two-state model of Hbs and provide the missing pieces of the intermediate structures that are required for full understanding of the allosteric nature of Hbs in detail.
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Affiliation(s)
- Nobutaka Numoto
- Medical Research Institute, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Yoshiaki Kawano
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Hideo Okumura
- Protein Crystal Analysis Division, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Seiki Baba
- Protein Crystal Analysis Division, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Yoshihiro Fukumori
- Nano Life Science Institute, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Kunio Miki
- Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Nobutoshi Ito
- Medical Research Institute, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
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Bellelli A, Tame JRH. Hemoglobin allostery and pharmacology. Mol Aspects Med 2021; 84:101037. [PMID: 34600771 DOI: 10.1016/j.mam.2021.101037] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 09/24/2021] [Accepted: 09/27/2021] [Indexed: 10/20/2022]
Abstract
The oxygen demands of the human body require the constant circulation of blood carrying an enormous concentration of hemoglobin (Hb). Oxygen transport depends not only on the amount of Hb, but also on the control over the affinity of the protein for the gas, which can be optimized for the environmental conditions by changes in the concentration of effectors (hydrogen ions, chloride, CO2, and DPG) inside the red cell. Some pathological conditions affecting Hb may benefit from pharmacological interventions to increase or decrease its affinity for oxygen, or otherwise modify its properties, or alter its biosynthesis. Examples of such conditions include sickle cell anemia, thalassemias and inherited hemoglobinopathies. Effective and safe drugs such as voxelotor, bezafibrate and efaproxiral are available that significantly increase or decrease Hb oxygen affinity. Some medical conditions not directly affecting the blood or its oxygen carrying capacity may also be relieved by the manipulation of Hb. For example, the standard treatment of acute cyanide poisoning requires the oxidation of a fraction of the Hb in the bloodstream so that it efficiently scavenges cyanide. Tumors are often extremely hypoxic and therefore strongly resistant to radiotherapy; the sensitivity of cancerous tissue to X-rays may be increased by improved oxygenation through drugs binding Hb. This review attempts to provide a systematic exploration of the pharmacology of Hb, its molecular basis, and its intended and possible uses.
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Affiliation(s)
- Andrea Bellelli
- Department of Biochemical Sciences "A. Rossi Fanelli", Sapienza University of Rome, Rome, Italy.
| | - Jeremy R H Tame
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Tsurumi, Yokohama, 230-0045, Japan
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Nagatomo S, Kitagawa T, Nagai M. Roles of Fe-Histidine bonds in stability of hemoglobin: Recognition of protein flexibility by Q Sepharose. Biophys J 2021; 120:2734-2745. [PMID: 34087219 DOI: 10.1016/j.bpj.2021.05.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 04/22/2021] [Accepted: 05/07/2021] [Indexed: 11/24/2022] Open
Abstract
Using various mutants, we investigated to date the roles of the Fe-histidine (F8) bonds in cooperative O2 binding of human hemoglobin (Hb) and differences in roles between α- and β-subunits in the α2β2 tetramer. An Hb variant with a mutation in the heme cavity exhibited an unexpected feature. When the β mutant rHb (βH92G), in which the proximal histidine (His F8) of the β-subunit is replaced by glycine (Gly), was subjected to ion-exchange chromatography (Q Sepharose column) and eluted with an NaCl concentration gradient in the presence of imidazole, yielded two large peaks, whereas the corresponding α-mutant, rHb (αH87G), gave a single peak similar to Hb A. The β-mutant rHb proteins under each peak had identical isoelectric points according to isoelectric focusing electrophoresis. Proteins under each peak were further characterized by Sephadex G-75 gel filtration, far-UV CD, 1H NMR, and resonance Raman spectroscopy. We found that rHb (βH92G) exists as a mixture of αβ-dimers and α2β2 tetramers, and that hemes are released from β-subunits in a fraction of the dimers. An approximate amount of released hemes were estimated to be as large as 30% with Raman relative intensities. It is stressed that Q Sepharose columns can distinguish differences in structural flexibility of proteins having identical isoelectric points by altering the exit rates from the porous beads. Thus, the role of Fe-His (F8) bonds in stabilizing the Hb tetramer first described by Barrick et al. was confirmed in this study. In addition, it was found in this study that a specific Fe-His bond in the β-subunit minimizes globin structural flexibility.
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Affiliation(s)
- Shigenori Nagatomo
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
| | - Teizo Kitagawa
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, Ako-gun, Hyogo, Japan.
| | - Masako Nagai
- Research Center for Micro-Nano Technology, Hosei University, Koganei, Tokyo, Japan; School of Health Sciences, College of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Ishikawa, Japan
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Ascenzi P, De Simone G, Pasquadibisceglie A, Gioia M, Coletta M. Kinetic inequivalence between α and β subunits of ligand dissociation from ferrous nitrosylated human haptoglobin:hemoglobin complexes. A comparison with O 2 and CO dissociation. J Inorg Biochem 2020; 214:111272. [PMID: 33129126 DOI: 10.1016/j.jinorgbio.2020.111272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 10/04/2020] [Accepted: 10/04/2020] [Indexed: 10/23/2022]
Abstract
Haptoglobin (Hp) counterbalances the adverse effects of extra-erythrocytic hemoglobin (Hb) by trapping the αβ dimers of Hb in the bloodstream. In turn, the Hp:Hb complexes display Hb-like reactivity. Here, the kinetics of NO dissociation from ferrous nitrosylated Hp:Hb complexes (i.e., Hp1-1:Hb(II)-NO and Hp2-2:Hb(II)-NO, respectively) are reported at pH 7.0 and 20.0 °C. NO dissociation from Hp:Hb(II)-NO complexes has been followed by replacing NO with CO. Denitrosylation kinetics of Hp1-1:Hb(II)-NO and Hp2-2:Hb(II)-NO are biphasic, the relative amplitude of the fast and slow phase being 0.495 ± 0.015 and 0.485 ± 0.025, respectively. Values of koff(NO)1 and koff(NO)2 (i.e., (6.4 ± 0.8) × 10-5 s-1 and (3.6 ± 0.6) × 10-5 s-1 for Hp1-1:Hb(II)-NO and (5.8 ± 0.8) × 10-5 s-1 and (3.1 ± 0.6) × 10-5 s-1 for Hp2-2:Hb(II)-NO) are unaffected by allosteric effectors and correspond to those reported for the α and β subunits of tetrameric Hb(II)-NO and isolated α(II)-NO and β(II)-NO chains, respectively. This highlights the view that the conformation of the Hb α1β1 and α2β2 dimers matches that of the Hb high affinity conformation. Moreover, the observed functional heterogeneity reflects the variation of energy barriers for the ligand detachment and exit pathway(s) associated to the different structural arrangement of the two subunits in the nitrosylated R-state. Noteworthy, the extent of the inequivalence of α and β chains is closely similar for the O2, NO and CO dissociation in the R-state, suggesting that it is solely determined by the structural difference between the two subunits.
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Affiliation(s)
- Paolo Ascenzi
- Interdepartmental Laboratory for Electron Microscopy, Roma Tre University, Via della Vasca Navale 79, I-00146 Roma, Italy.
| | - Giovanna De Simone
- Department of Sciences, Roma Tre University, Viale Guglielmo Marconi 79, I-00146 Roma, Italy
| | | | - Magda Gioia
- Department of Clinical Sciences and Translational Medicine, University of Roma "Tor Vergata", Via Montpellier 1, I-00133 Roma, Italy; Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems, Via Celso Ulpiani 27, I-70126, Bari, Italy
| | - Massimo Coletta
- Department of Clinical Sciences and Translational Medicine, University of Roma "Tor Vergata", Via Montpellier 1, I-00133 Roma, Italy; Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems, Via Celso Ulpiani 27, I-70126, Bari, Italy
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Shibayama N. Allosteric transitions in hemoglobin revisited. Biochim Biophys Acta Gen Subj 2020; 1864:129335. [DOI: 10.1016/j.bbagen.2019.03.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 03/27/2019] [Accepted: 03/30/2019] [Indexed: 12/19/2022]
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On the perturbation nature of allostery: sites, mutations, and signal modulation. Curr Opin Struct Biol 2019; 56:18-27. [DOI: 10.1016/j.sbi.2018.10.008] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 10/27/2018] [Accepted: 10/30/2018] [Indexed: 10/27/2022]
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