1
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Li Y, Han S, Gao H. Heme homeostasis and its regulation by hemoproteins in bacteria. MLIFE 2024; 3:327-342. [PMID: 39359680 PMCID: PMC11442138 DOI: 10.1002/mlf2.12120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 02/08/2024] [Accepted: 02/23/2024] [Indexed: 10/04/2024]
Abstract
Heme is an important cofactor and a regulatory molecule involved in various physiological processes in virtually all living cellular organisms, and it can also serve as the primary iron source for many bacteria, particularly pathogens. However, excess heme is cytotoxic to cells. In order to meet physiological needs while preventing deleterious effects, bacteria have evolved sophisticated cellular mechanisms to maintain heme homeostasis. Recent advances in technologies have shaped our understanding of the molecular mechanisms that govern the biological processes crucial to heme homeostasis, including synthesis, acquisition, utilization, degradation, trafficking, and efflux, as well as their regulation. Central to these mechanisms is the regulation of the heme, by the heme, and for the heme. In this review, we present state-of-the-art findings covering the biochemical, physiological, and structural characterization of important, newly identified hemoproteins/systems involved in heme homeostasis.
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Affiliation(s)
- Yingxi Li
- Institute of Microbiology and College of Life SciencesZhejiang UniversityHangzhouChina
| | - Sirui Han
- Institute of Microbiology and College of Life SciencesZhejiang UniversityHangzhouChina
| | - Haichun Gao
- Institute of Microbiology and College of Life SciencesZhejiang UniversityHangzhouChina
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2
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Reeder BJ, Svistunenko DA, Wilson MT. Hell's Gate Globin-I from Methylacidiphilum infernorum Displays a Unique Temperature-Independent pH Sensing Mechanism Utililized a Lipid-Induced Conformational Change. Int J Mol Sci 2024; 25:6794. [PMID: 38928500 PMCID: PMC11203436 DOI: 10.3390/ijms25126794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 06/05/2024] [Accepted: 06/14/2024] [Indexed: 06/28/2024] Open
Abstract
Hell's Gate globin-I (HGb-I) is a thermally stable globin from the aerobic methanotroph Methylacidiphilium infernorum. Here we report that HGb-I interacts with lipids stoichiometrically to induce structural changes in the heme pocket, changing the heme iron distal ligation coordination from hexacoordinate to pentacoordinate. Such changes in heme geometry have only been previously reported for cytochrome c and cytoglobin, linked to apoptosis regulation and enhanced lipid peroxidation activity, respectively. However, unlike cytoglobin and cytochrome c, the heme iron of HGb-I is altered by lipids in ferrous as well as ferric oxidation states. The apparent affinity for lipids in this thermally stable globin is highly pH-dependent but essentially temperature-independent within the range of 20-60 °C. We propose a mechanism to explain these observations, in which lipid binding and stability of the distal endogenous ligand are juxtaposed as a function of temperature. Additionally, we propose that these coupled equilibria may constitute a mechanism through which this acidophilic thermophile senses the pH of its environment.
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Affiliation(s)
- Brandon J. Reeder
- School of Biological Sciences, University of Essex, Wivenhoe Park Colchester, Essex CO4 3SQ, UK; (D.A.S.); (M.T.W.)
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3
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Lecomte JTJ, Johnson EA. The globins of cyanobacteria and green algae: An update. Adv Microb Physiol 2024; 85:97-144. [PMID: 39059824 DOI: 10.1016/bs.ampbs.2024.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2024]
Abstract
The globin superfamily of proteins is ancient and diverse. Regular assessments based on the increasing number of available genome sequences have elaborated on a complex evolutionary history. In this review, we present a summary of a decade of advances in characterising the globins of cyanobacteria and green algae. The focus is on haem-containing globins with an emphasis on recent experimental developments, which reinforce links to nitrogen metabolism and nitrosative stress response in addition to dioxygen management. Mention is made of globins that do not bind haem to provide an encompassing view of the superfamily and perspective on the field. It is reiterated that an effort toward phenotypical and in-vivo characterisation is needed to elucidate the many roles that these versatile proteins fulfil in oxygenic photosynthetic microbes. It is also proposed that globins from oxygenic organisms are promising proteins for applications in the biotechnology arena.
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Affiliation(s)
- Juliette T J Lecomte
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, United States.
| | - Eric A Johnson
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States
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4
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Freindorf M, Antonio JJ, Kraka E. Iron-histidine bonding in bishistidyl hemoproteins-A local vibrational mode study. J Comput Chem 2024; 45:574-588. [PMID: 38041830 DOI: 10.1002/jcc.27267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 11/09/2023] [Accepted: 11/11/2023] [Indexed: 12/04/2023]
Abstract
We investigated the intrinsic strength of distal and proximal FeN bonds for both ferric and ferrous oxidation states of bishistidyl hemoproteins from bacteria, animals, human, and plants, including two cytoglobins, ten hemoglobins, two myoglobins, six neuroglobins, and six phytoglobins. As a qualified measure of bond strength, we used local vibrational force constants ka (FeN) based on local mode theory developed in our group. All calculations were performed with a hybrid QM/MM ansatz. Starting geometries were taken from available x-ray structures. ka (FeN) values were correlated with FeN bond lengths and covalent bond character. We also investigated the stiffness of the axial NFeN bond angle. Our results highlight that protein effects are sensitively reflected in ka (FeN), allowing one to compare trends in diverse protein groups. Moreover, ka (NFeN) is a perfect tool to monitor changes in the axial heme framework caused by different protein environments as well as different Fe oxidation states.
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Affiliation(s)
- Marek Freindorf
- Chemistry Department, Southern Methodist University, Dallas, Texas, USA
| | - Juliana J Antonio
- Chemistry Department, Southern Methodist University, Dallas, Texas, USA
| | - Elfi Kraka
- Chemistry Department, Southern Methodist University, Dallas, Texas, USA
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5
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De Simone G, di Masi A, Tundo GR, Coletta M, Ascenzi P. Nitrite Reductase Activity of Ferrous Nitrobindins: A Comparative Study. Int J Mol Sci 2023; 24:ijms24076553. [PMID: 37047528 PMCID: PMC10094804 DOI: 10.3390/ijms24076553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/17/2023] [Accepted: 03/20/2023] [Indexed: 04/03/2023] Open
Abstract
Nitrobindins (Nbs) are all-β-barrel heme proteins spanning from bacteria to Homo sapiens. They inactivate reactive nitrogen species by sequestering NO, converting NO to HNO2, and promoting peroxynitrite isomerization to NO3−. Here, the nitrite reductase activity of Nb(II) from Mycobacterium tuberculosis (Mt-Nb(II)), Arabidopsis thaliana (At-Nb(II)), Danio rerio (Dr-Nb(II)), and Homo sapiens (Hs-Nb(II)) is reported. This activity is crucial for the in vivo production of NO, and thus for the regulation of blood pressure, being of the utmost importance for the blood supply to poorly oxygenated tissues, such as the eye retina. At pH 7.3 and 20.0 °C, the values of the second-order rate constants (i.e., kon) for the reduction of NO2− to NO and the concomitant formation of nitrosylated Mt-Nb(II), At-Nb(II), Dr-Nb(II), and Hs-Nb(II) (Nb(II)-NO) were 7.6 M−1 s−1, 9.3 M−1 s−1, 1.4 × 101 M−1 s−1, and 5.8 M−1 s−1, respectively. The values of kon increased linearly with decreasing pH, thus indicating that the NO2−-based conversion of Nb(II) to Nb(II)-NO requires the involvement of one proton. These results represent the first evidence for the NO2 reductase activity of Nbs(II), strongly supporting the view that Nbs are involved in NO metabolism. Interestingly, the nitrite reductase reactivity of all-β-barrel Nbs and of all-α-helical globins (e.g., myoglobin) was very similar despite the very different three-dimensional fold; however, differences between all-α-helical globins and all-β-barrel Nbs suggest that nitrite reductase activity appears to be controlled by distal steric barriers, even though a more complex regulatory mechanism can be also envisaged.
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Affiliation(s)
| | | | - Grazia R. Tundo
- Dipartimento di Scienze Cliniche e Medicina Traslazionale, Università di Roma Tor Vergata, 00133 Roma, Italy
| | | | - Paolo Ascenzi
- Laboratorio Interdipartimentale di Microscopia Elettronica, Università Roma Tre, 00146 Roma, Italy
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6
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Nardini M, Pesce A, Bolognesi M. Truncated (2/2) hemoglobin: Unconventional structures and functional roles in vivo and in human pathogenesis. Mol Aspects Med 2021; 84:101049. [PMID: 34776271 DOI: 10.1016/j.mam.2021.101049] [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: 10/22/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 12/12/2022]
Abstract
Truncated hemoglobins (trHbs) build a sub-class of the globin family, found in eubacteria, cyanobacteria, unicellular eukaryotes, and in higher plants; among these, selected human pathogens are found. The trHb fold is based on a 2/2 α-helical sandwich, consisting of a simplified and reduced-size version of the classical 3/3 α-helical sandwich of vertebrate and invertebrate globins. Phylogenetic analysis indicates that trHbs further branch into three groups: group I (or trHbN), group II (or trHbO), and group III (or trHbP), each group being characterized by specific structural features. Among these, a protein matrix tunnel, or a cavity system implicated in diatomic ligand diffusion through the protein matrix, is typical of group I and group II, respectively. In general, a highly intertwined network of hydrogen bonds stabilizes the heme bound ligand, despite variability of the heme distal residues in the different trHb groups. Notably, some organisms display genes from more than one trHb group, suggesting that trHbN, trHbO, and trHbP may support different functions in vivo, such as detoxification of reactive nitrogen and oxygen species, respiration, oxygen storage/sensoring, thus aiding survival of an invading microorganism. Here, structural features and proposed functions of trHbs from human pathogens are reviewed.
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Affiliation(s)
- Marco Nardini
- Department of Biosciences, University of Milano, Milano, Italy
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7
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Uppal S, Khan MA, Kundu S. Stability and Folding of the Unusually Stable Hemoglobin from Synechocystis is Subtly Optimized and Dependent on the Key Heme Pocket Residues. Protein Pept Lett 2021; 28:164-182. [PMID: 32533815 DOI: 10.2174/0929866527666200613220245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/20/2020] [Accepted: 04/24/2020] [Indexed: 11/22/2022]
Abstract
AIMS The aim of our study is to understand the biophysical traits that govern the stability and folding of Synechocystis hemoglobin, a unique cyanobacterial globin that displays unusual traits not observed in any of the other globins discovered so far. BACKGROUND For the past few decades, classical hemoglobins such as vertebrate hemoglobin and myoglobin have been extensively studied to unravel the stability and folding mechanisms of hemoglobins. However, the expanding wealth of hemoglobins identified in all life forms with novel properties, like heme coordination chemistry and globin fold, have added complexity and challenges to the understanding of hemoglobin stability, which has not been adequately addressed. Here, we explored the unique truncated and hexacoordinate hemoglobin from the freshwater cyanobacterium Synechocystis sp. PCC 6803 known as "Synechocystis hemoglobin (SynHb)". The "three histidines" linkages to heme are novel to this cyanobacterial hemoglobin. OBJECTIVE Mutational studies were employed to decipher the residues within the heme pocket that dictate the stability and folding of SynHb. METHODS Site-directed mutants of SynHb were generated and analyzed using a repertoire of spectroscopic and calorimetric tools. RESULTS The results revealed that the heme was stably associated to the protein under all denaturing conditions with His117 playing the anchoring role. The studies also highlighted the possibility of existence of a "molten globule" like intermediate at acidic pH in this exceptionally thermostable globin. His117 and other key residues in the heme pocket play an indispensable role in imparting significant polypeptide stability. CONCLUSION Synechocystis hemoglobin presents an important model system for investigations of protein folding and stability in general. The heme pocket residues influenced the folding and stability of SynHb in a very subtle and specific manner and may have been optimized to make this Hb the most stable known as of date. Other: The knowledge gained hereby about the influence of heme pocket amino acid side chains on stability and expression is currently being utilized to improve the stability of recombinant human Hbs for efficient use as oxygen delivery vehicles.
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Affiliation(s)
- Sheetal Uppal
- Department of Biochemistry, University of Delhi South Campus, New Delhi, 110021, India
| | - Mohd Asim Khan
- Department of Biochemistry, University of Delhi South Campus, New Delhi, 110021, India
| | - Suman Kundu
- Department of Biochemistry, University of Delhi South Campus, New Delhi, 110021, India
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8
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Nye DB, Johnson EA, Mai MH, Lecomte JTJ. Replacement of the heme axial lysine as a test of conformational adaptability in the truncated hemoglobin THB1. J Inorg Biochem 2019; 201:110824. [PMID: 31514090 DOI: 10.1016/j.jinorgbio.2019.110824] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/03/2019] [Accepted: 09/03/2019] [Indexed: 10/26/2022]
Abstract
Amino acid replacement is a useful strategy to assess the roles of axial heme ligands in the function of native heme proteins. THB1, the protein product of the Chlamydomonas reinhardtii THB1 gene, is a group 1 truncated hemoglobin that uses a lysine residue in the E helix (Lys53, at position E10 by reference to myoglobin) as an iron ligand at neutral pH. Phylogenetic evidence shows that many homologous proteins have a histidine, methionine or arginine at the same position. In THB1, these amino acids would each be expected to convey distinct reactive properties if replacing the native lysine as an axial ligand. To explore the ability of the group 1 truncated Hb fold to support alternative ligation schemes and distal pocket conformations, the properties of the THB1 variants K53A as a control, K53H, K53M, and K53R were investigated by electronic absorption, EPR, and NMR spectroscopies. We found that His53 is capable of heme ligation in both the Fe(III) and Fe(II) states, that Met53 can coordinate only in the Fe(II) state, and that Arg53 stabilizes a hydroxide ligand in the Fe(III) state. The data illustrate that the group 1 truncated Hb fold can tolerate diverse rearrangement of the heme environment and has a strong tendency to use two protein side chains as iron ligands despite accompanying structural perturbations. Access to various redox pairs and different responses to pH make this protein an excellent test case for energetic and dynamic studies of heme ligation.
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Affiliation(s)
- Dillon B Nye
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Eric A Johnson
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Melissa H Mai
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Juliette T J Lecomte
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
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9
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Ascenzi P, De Simone G, Ciaccio C, Santucci R, Coletta M. Hydroxylamine-induced oxidation of ferrous CO-bound carboxymethylated-cytochrome c. J PORPHYR PHTHALOCYA 2018. [DOI: 10.1142/s1088424618501055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The hexa-coordinated metal center of horse heart cyt[Formula: see text] (cyt[Formula: see text] is at the root of its low reactivity. In contrast, carboxymethylated cyt[Formula: see text] (CM-cyt[Formula: see text] displays myoglobin-like properties. Herein, kinetics of CO binding to ferrous CM-cyt[Formula: see text] (CM-cyt[Formula: see text](II)) and of the irreversible oxidation of ferrous carbonylated CM-cyt[Formula: see text] (CM-cyt[Formula: see text](II)-CO) by hydroxylamine (HA), at pH 5.8 and 20.0 [Formula: see text]C, are reported. HA irreversibly oxidizes CM-cyt[Formula: see text](II)-CO with the 1:2 stoichiometry leading to the formation of the ferric species (CM-cyt[Formula: see text](III)) without the observation of intermediates. Present data indicate that: (i) the rate of CO dissociation from CM-cyt[Formula: see text](II)-CO represents the rate-limiting step of HA-mediated oxidation of the carbonylated metal center, (ii) the fast oxidation of CM-cyt[Formula: see text](II)-CO from HA reflects the penta-coordination of the transient CM-cyt[Formula: see text](II) species, (iii) the HA-catalyzed conversion of CM-cyt[Formula: see text](II)-CO to CM-cyt[Formula: see text](III) could proceed via the geminate mechanism, (iv) values of the second-order rate constants for the carbonylation and the HA-mediated oxidation of ferrous heme-proteins are linearly correlated reflecting the penta- or hexa-coordination of the metal center, the free energy for the in-plane positioning of the heme-Fe atom in the unliganded species, and the arrangement of the distal portion of the heme pocket that affects ligand and/or electron transfer.
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Affiliation(s)
- Paolo Ascenzi
- Interdepartmental Laboratory for Electron Microscopy, Roma Tre University, I-00146 Roma, Italy
| | | | - Chiara Ciaccio
- Department of Clinical Sciences and Translational Medicine, University of Roma “Tor Vergata”, I-00133 Roma, Italy
- Interuniversity Consortium for the Research on Chemistry of Metals in Biological Systems, I-70126 Bari, Italy
| | - Roberto Santucci
- Department of Clinical Sciences and Translational Medicine, University of Roma “Tor Vergata”, I-00133 Roma, Italy
| | - Massimo Coletta
- Department of Clinical Sciences and Translational Medicine, University of Roma “Tor Vergata”, I-00133 Roma, Italy
- Interuniversity Consortium for the Research on Chemistry of Metals in Biological Systems, I-70126 Bari, Italy
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10
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Nye DB, Lecomte JTJ. Replacement of the Distal Histidine Reveals a Noncanonical Heme Binding Site in a 2-on-2 Hemoglobin. Biochemistry 2018; 57:5785-5796. [PMID: 30213188 PMCID: PMC6217817 DOI: 10.1021/acs.biochem.8b00752] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Heme ligation in hemoglobin is typically assumed by the "proximal" histidine. Hydrophobic contacts, ionic interactions, and the ligation bond secure the heme between two α-helices denoted E and F. Across the hemoglobin superfamily, several proteins also use a "distal" histidine, making the native state a bis-histidine complex. The group 1 truncated hemoglobin from Synechocystis sp. PCC 6803, GlbN, is one such bis-histidine protein. Ferric GlbN, in which the distal histidine (His46 or E10) has been replaced with a leucine, though expected to bind a water molecule and yield a high-spin iron complex at neutral pH, has low-spin spectral properties. Here, we applied nuclear magnetic resonance and electronic absorption spectroscopic methods to GlbN modified with heme and amino acid replacements to identify the distal ligand in H46L GlbN. We found that His117, a residue located in the C-terminal portion of the protein and on the proximal side of the heme, is responsible for the formation of an alternative bis-histidine complex. Simultaneous coordination by His70 and His117 situates the heme in a binding site different from the canonical site. This new holoprotein form is achieved with only local conformational changes. Heme affinity in the alternative site is weaker than in the normal site, likely because of strained coordination and a reduced number of specific heme-protein interactions. The observation of an unconventional heme binding site has important implications for the interpretation of mutagenesis results and globin homology modeling.
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Affiliation(s)
- Dillon B. Nye
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, United States
| | - Juliette T. J. Lecomte
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, United States
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11
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Gell DA. Structure and function of haemoglobins. Blood Cells Mol Dis 2017; 70:13-42. [PMID: 29126700 DOI: 10.1016/j.bcmd.2017.10.006] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Revised: 10/29/2017] [Accepted: 10/30/2017] [Indexed: 12/18/2022]
Abstract
Haemoglobin (Hb) is widely known as the iron-containing protein in blood that is essential for O2 transport in mammals. Less widely recognised is that erythrocyte Hb belongs to a large family of Hb proteins with members distributed across all three domains of life-bacteria, archaea and eukaryotes. This review, aimed chiefly at researchers new to the field, attempts a broad overview of the diversity, and common features, in Hb structure and function. Topics include structural and functional classification of Hbs; principles of O2 binding affinity and selectivity between O2/NO/CO and other small ligands; hexacoordinate (containing bis-imidazole coordinated haem) Hbs; bacterial truncated Hbs; flavohaemoglobins; enzymatic reactions of Hbs with bioactive gases, particularly NO, and protection from nitrosative stress; and, sensor Hbs. A final section sketches the evolution of work on the structural basis for allosteric O2 binding by mammalian RBC Hb, including the development of newer kinetic models. Where possible, reference to historical works is included, in order to provide context for current advances in Hb research.
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Affiliation(s)
- David A Gell
- School of Medicine, University of Tasmania, TAS 7000, Australia.
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12
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Uppal S, Singh AK, Arya R, Tewari D, Jaiswal N, Kapoor A, Bera AK, Nag A, Kundu S. Phe28 B10 Induces Channel-Forming Cytotoxic Amyloid Fibrillation in Human Neuroglobin, the Brain-Specific Hemoglobin. Biochemistry 2016; 55:6832-6847. [PMID: 27951646 DOI: 10.1021/acs.biochem.6b00617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Since its discovery, neuroglobin (Ngb), a neuron-specific oxygen binding hemoglobin, distinct from the classical myoglobin and blood hemoglobin, has attracted attention as an endogenous neuroprotectant. Recent reports suggest that Ngb protects neurons from brain stroke, ischemic stress-induced degeneration, and other brain disorders. Proteins with a specific role in neuroprotection are often associated with neurodegeneration, as well, depending on the cellular environment or specific cellular triggers that tilt the balance one way or the other. This investigation explored the potential role of Ngb in amyloid fibril-related neuronal disorder. Ngb was capable of amyloid formation in vitro at neutral pH and ambient temperature, in both apo and holo forms, albeit at a slower rate in the holo form, unlike other hemoglobins that exhibit such behavior exclusively in the apo states. Elevated temperature enhanced the rate of fibril formation significantly. The B-helix, which is known to play a major role in Ngb ligand binding kinetics, was found to be amyloidogenic with the Phe28B10 amino acid side chain as the key inducer of fibrillation. The Ngb amyloid fibril was also significantly cytotoxic to neuroblastoma cell lines, compared to those obtained from reference hemoglobins. The Ngb fibril probably promoted toxicity by inducing channel formation in the cell membrane, as investigated here using synthetic lipid bilayer membranes and the propidium iodide uptake assay. These findings imply that Ngb plays a role in neurodegenerative disorders in vivo, for which there seems to be indirect evidence by association. Ngb thus presents a novel prospect for understanding amyloid-related brain disorders beyond the limited set of proteins currently investigated for such diseases.
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Affiliation(s)
- Sheetal Uppal
- Department of Biochemistry, University of Delhi South Campus , New Delhi 110021, India
| | - Amit Kumar Singh
- Department of Biochemistry, University of Delhi South Campus , New Delhi 110021, India
| | - Richa Arya
- Department of Biochemistry, University of Delhi South Campus , New Delhi 110021, India
| | - Debanjan Tewari
- Department of Biotechnology, Indian Institute of Technology Madras , Chennai 600036, India
| | - Neha Jaiswal
- Department of Biochemistry, University of Delhi South Campus , New Delhi 110021, India
| | - Abhijeet Kapoor
- Department of Biochemistry, University of Delhi South Campus , New Delhi 110021, India
| | - Amal Kanti Bera
- Department of Biotechnology, Indian Institute of Technology Madras , Chennai 600036, India
| | - Alo Nag
- Department of Biochemistry, University of Delhi South Campus , New Delhi 110021, India
| | - Suman Kundu
- Department of Biochemistry, University of Delhi South Campus , New Delhi 110021, India
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13
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Bustamante JP, Szretter ME, Sued M, Martí MA, Estrin DA, Boechi L. A quantitative model for oxygen uptake and release in a family of hemeproteins. Bioinformatics 2016; 32:1805-13. [PMID: 27153569 DOI: 10.1093/bioinformatics/btw083] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 01/30/2016] [Indexed: 11/14/2022] Open
Abstract
MOTIVATION Hemeproteins have many diverse functions that largely depend on the rate at which they uptake or release small ligands, like oxygen. These proteins have been extensively studied using either simulations or experiments, albeit only qualitatively and one or two proteins at a time. RESULTS We present a physical-chemical model, which uses data obtained exclusively from computer simulations, to describe the uptake and release of oxygen in a family of hemeproteins, called truncated hemoglobins (trHbs). Through a rigorous statistical analysis we demonstrate that our model successfully recaptures all the reported experimental oxygen association and dissociation kinetic rate constants, thus allowing us to establish the key factors that determine the rates at which these hemeproteins uptake and release oxygen. We found that internal tunnels as well as the distal site water molecules control ligand uptake, whereas oxygen stabilization by distal site residues controls ligand release. Because these rates largely determine the functions of these hemeproteins, these approaches will also be important tools in characterizing the trHbs members with unknown functions. CONTACT lboechi@ic.fcen.uba.ar SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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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
| | - María E Szretter
- Instituto De Cálculo, Facultad De Ciencias Exactas Y Naturales, Universidad De Buenos Aires Departamento De Matemática, Facultad De Ciencias Exactas Y Naturales, Universidad De Buenos Aires
| | - Mariela Sued
- Instituto De Cálculo, Facultad De Ciencias Exactas Y Naturales, Universidad De Buenos Aires
| | - Marcelo A Martí
- 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
| | - Darío A Estrin
- Departamento de Química Inorgánica, Analítica Y Química Física, INQUIMAE-CONICET, Facultad De Ciencias Exactas Y Naturales, Universidad De Buenos Aires
| | - Leonardo Boechi
- Instituto De Cálculo, Facultad De Ciencias Exactas Y Naturales, Universidad De Buenos Aires
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14
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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: 34] [Impact Index Per Article: 4.3] [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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Ascenzi P, Sbardella D, Fiocchetti M, Santucci R, Coletta M. NO2−-mediated nitrosylation of ferrous microperoxidase-11. J Inorg Biochem 2015; 153:121-127. [DOI: 10.1016/j.jinorgbio.2015.06.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 06/03/2015] [Accepted: 06/30/2015] [Indexed: 11/29/2022]
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16
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Open and Lys-His Hexacoordinated Closed Structures of a Globin with Swapped Proximal and Distal Sites. Sci Rep 2015; 5:11407. [PMID: 26094577 PMCID: PMC4476040 DOI: 10.1038/srep11407] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 05/22/2015] [Indexed: 11/24/2022] Open
Abstract
Globins are haem-binding proteins with a conserved fold made up of α-helices and can possess diverse properties. A putative globin-coupled sensor from Methylacidiphilum infernorum, HGbRL, contains an N-terminal globin domain whose open and closed structures reveal an untypical dimeric architecture. Helices E and F fuse into an elongated helix, resulting in a novel site-swapped globin fold made up of helices A–E, hence the distal site, from one subunit and helices F–H, the proximal site, from another. The open structure possesses a large cavity binding an imidazole molecule, while the closed structure forms a unique Lys–His hexacoordinated species, with the first turn of helix E unravelling to allow Lys52(E10) to bind to the haem. Ligand binding induces reorganization of loop CE, which is stabilized in the closed form, and helix E, triggering a large conformational movement in the open form. These provide a mechanical insight into how a signal may be relayed between the globin domain and the C-terminal domain of HGbRL, a Roadblock/LC7 domain. Comparison with HGbI, a closely related globin, further underlines the high degree of structural versatility that the globin fold is capable of, enabling it to perform a diversity of functions.
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17
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Rice SL, Boucher LE, Schlessman JL, Preimesberger MR, Bosch J, Lecomte JTJ. Structure of Chlamydomonas reinhardtii THB1, a group 1 truncated hemoglobin with a rare histidine-lysine heme ligation. Acta Crystallogr F Struct Biol Commun 2015; 71:718-25. [PMID: 26057801 PMCID: PMC4461336 DOI: 10.1107/s2053230x15006949] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 04/07/2015] [Indexed: 04/05/2023] Open
Abstract
THB1 is one of several group 1 truncated hemoglobins (TrHb1s) encoded in the genome of the unicellular green alga Chlamydomonas reinhardtii. THB1 expression is under the control of NIT2, the master regulator of nitrate assimilation, which also controls the expression of the only nitrate reductase in the cell, NIT1. In vitro and physiological evidence suggests that THB1 converts the nitric oxide generated by NIT1 into nitrate. To aid in the elucidation of the function and mechanism of THB1, the structure of the protein was solved in the ferric state. THB1 resembles other TrHb1s, but also exhibits distinct features associated with the coordination of the heme iron by a histidine (proximal) and a lysine (distal). The new structure illustrates the versatility of the TrHb1 fold, suggests factors that stabilize the axial ligation of a lysine, and highlights the difficulty of predicting the identity of the distal ligand, if any, in this group of proteins.
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Affiliation(s)
- Selena L. Rice
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Lauren E. Boucher
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA
- Johns Hopkins Malaria Research Institute, Johns Hopkins University, Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA
| | - Jamie L. Schlessman
- Chemistry Department, US Naval Academy, 572 Holloway Road, Annapolis, MD 21402, USA
| | - Matthew R. Preimesberger
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Jürgen Bosch
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA
- Johns Hopkins Malaria Research Institute, Johns Hopkins University, Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA
| | - Juliette T. J. Lecomte
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
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18
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Nitrite reduction by molybdoenzymes: a new class of nitric oxide-forming nitrite reductases. J Biol Inorg Chem 2015; 20:403-33. [DOI: 10.1007/s00775-014-1234-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 12/14/2014] [Indexed: 02/07/2023]
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19
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Abstract
In the last few years, advances in algal research have identified the participation of haemoglobins in nitrogen metabolism and the management of reactive nitrogen and oxygen species. This chapter summarises the state of knowledge concerning algal haemoglobins with a focus on the most widely used model system, namely, Chlamydomonas reinhardtii. Genetic, physiologic, structural, and chemical information is compiled to provide a framework for further studies.
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Affiliation(s)
- Eric A Johnson
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
| | - Juliette T J Lecomte
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, USA.
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20
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Uppal S, Salhotra S, Mukhi N, Zaidi FK, Seal M, Dey SG, Bhat R, Kundu S. Significantly enhanced heme retention ability of myoglobin engineered to mimic the third covalent linkage by nonaxial histidine to heme (vinyl) in synechocystis hemoglobin. J Biol Chem 2014; 290:1979-93. [PMID: 25451928 DOI: 10.1074/jbc.m114.603225] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heme proteins, which reversibly bind oxygen and display a particular fold originally identified in myoglobin (Mb), characterize the "hemoglobin (Hb) superfamily." The long known and widely investigated Hb superfamily, however, has been enriched by the discovery and investigation of new classes and members. Truncated Hbs typify such novel classes and exhibit a distinct two-on-two α-helical fold. The truncated Hb from the freshwater cyanobacterium Synechocystis exhibits hexacoordinate heme chemistry and bears an unusual covalent bond between the nonaxial His(117) and a heme porphyrin 2-vinyl atom, which remains tightly associated with the globin unlike any other. It seems to be the most stable Hb known to date, and His(117) is the dominant force holding the heme. Mutations of amino acid residues in the vicinity did not influence this covalent linkage. Introduction of a nonaxial His into sperm whale Mb at the topologically equivalent position and in close proximity to vinyl group significantly increased the heme stability of this prototype globin. Reversed phase chromatography, electrospray ionization-MS, and MALDI-TOF analyses confirmed the presence of covalent linkage in Mb I107H. The Mb mutant with the engineered covalent linkage was stable to denaturants and exhibited ligand binding and auto-oxidation rates similar to the wild type protein. This indeed is a novel finding and provides a new perspective to the evolution of Hbs. The successful attempt at engineering heme stability holds promise for the production of stable Hb-based blood substitute.
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Affiliation(s)
- Sheetal Uppal
- From the Department of Biochemistry, University of Delhi South Campus, New Delhi 110021, India
| | - Shikha Salhotra
- From the Department of Biochemistry, University of Delhi South Campus, New Delhi 110021, India
| | - Nitika Mukhi
- From the Department of Biochemistry, University of Delhi South Campus, New Delhi 110021, India
| | - Fatima Kamal Zaidi
- the School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India, and
| | - Manas Seal
- the Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Somdatta Ghosh Dey
- the Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Rajiv Bhat
- the School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India, and
| | - Suman Kundu
- From the Department of Biochemistry, University of Delhi South Campus, New Delhi 110021, India,
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21
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Abstract
Small size globins that have been defined as 'truncated haemoglobins' or as '2/2 haemoglobins' have increasingly been discovered in microorganisms since the early 1990s. Analysis of amino acid sequences allowed to distinguish three groups that collect proteins with specific and common structural properties. All three groups display 3D structures that are based on four main α-helices, which are a subset of the conventional eight-helices globin fold. Specific features, such as the presence of protein matrix tunnels that are held to promote diffusion of functional ligands to/from the haem, distinguish members of the three groups. Haem distal sites vary for their accessibility, local structures, polarity, and ligand stabilization mechanisms, suggesting functional roles that are related to O2/NO chemistry. In a few cases, such activities have been proven in vitro and in vivo through deletion mutants. The issue of 2/2 haemoglobin varied biological functions throughout the three groups remains however fully open.
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22
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Affiliation(s)
- Luisa B. Maia
- REQUIMTE/CQFB, Departamento
de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - José J. G. Moura
- REQUIMTE/CQFB, Departamento
de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
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23
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Wenke BB, Lecomte JTJ, Héroux A, Schlessman JL. The 2/2 hemoglobin from the cyanobacterium Synechococcus
sp. PCC 7002 with covalently attached heme: Comparison of X-ray and NMR structures. Proteins 2013; 82:528-34. [DOI: 10.1002/prot.24409] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 08/22/2013] [Accepted: 08/26/2013] [Indexed: 12/17/2022]
Affiliation(s)
- Belinda B. Wenke
- T.C. Jenkins Department of Biophysics; Johns Hopkins University; Baltimore Maryland 21218
| | - Juliette T. J. Lecomte
- T.C. Jenkins Department of Biophysics; Johns Hopkins University; Baltimore Maryland 21218
| | - Annie Héroux
- Photon Sciences Directorate; Brookhaven National Laboratory; Upton New York 11973
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24
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Vinogradov SN, Tinajero-Trejo M, Poole RK, Hoogewijs D. Bacterial and archaeal globins — A revised perspective. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:1789-800. [DOI: 10.1016/j.bbapap.2013.03.021] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 02/12/2013] [Accepted: 03/16/2013] [Indexed: 12/17/2022]
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25
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Preimesberger MR, Wenke BB, Gilevicius L, Pond MP, Lecomte JTJ. Facile heme vinyl posttranslational modification in a hemoglobin. Biochemistry 2013; 52:3478-88. [PMID: 23607716 DOI: 10.1021/bi400289e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Iron-protoporphyrin IX, or b heme, is utilized as such by a large number of proteins and enzymes. In some cases, notably the c-type cytochromes, this group undergoes a posttranslational covalent attachment to the polypeptide chain, which adjusts the physicochemical properties of the holoprotein. The hemoglobin from the cyanobacterium Synechocystis sp. PCC 6803 (GlbN), contrary to the archetypical hemoglobin, modifies its b heme covalently. The posttranslational modification links His117, a residue that does not coordinate the iron, to the porphyrin 2-vinyl substituent and forms a hybrid b/c heme. The reaction is an electrophilic addition that occurs spontaneously in the ferrous state of the protein. This apparently facile type of heme modification has been observed in only two cyanobacterial GlbNs. To explore the determinants of the reaction, we examined the behavior of Synechocystis GlbN variants containing a histidine at position 79, which is buried against the porphyrin 4-vinyl substituent. We found that L79H/H117A GlbN bound the heme weakly but nevertheless formed a cross-link between His79 Nε2 and the heme 4-Cα. In addition to this linkage, the single variant L79H GlbN also formed the native His117-2-Cα bond yielding an unprecedented bis-alkylated protein adduct. The ability to engineer the doubly modified protein indicates that the histidine-heme modification in GlbN is robust and could be engineered in different local environments. The rarity of the histidine linkage in natural proteins, despite the ease of reaction, is proposed to stem from multiple sources of negative selection.
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Affiliation(s)
- Matthew R Preimesberger
- T. C. Jenkins Department of Biophysics, Johns Hopkins University , Baltimore, Maryland 21218, United States
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26
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Pond MP, Wenke BB, Preimesberger MR, Rice SL, Lecomte JTJ. 3-Fluorotyrosine as a complementary probe of hemoglobin structure and dynamics: a (19)F-NMR study of Synechococcus sp. PCC 7002 GlbN. Chem Biodivers 2013; 9:1703-17. [PMID: 22976963 DOI: 10.1002/cbdv.201100448] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The hemoglobin from the cyanobacterium Synechococcus sp. PCC 7002 (GlbN) contains three tyrosines (Tyr5, Tyr22, and Tyr53), each of which undergoes a structural rearrangement when the protein binds an exogenous ligand such as cyanide. We explored the use of 3-fluorotyrosine and (19)F-NMR spectroscopy for the characterization of GlbN. Assignment of (19)F resonances in fluorinated GlbN (GlbN*) was achieved with individual Tyr5Phe and Tyr53Phe replacements. We observed marked variations in chemical shift and linewidth reflecting the dependence of structural and dynamic properties on oxidation state, ligation state, and covalent attachment of the heme group. The isoelectronic complexes of ferric GlbN* with cyanide and ferrous GlbN* with carbon monoxide gave contrasting spectra, the latter exhibiting heterogeneity and enhanced internal motions on a microsecond-to-millisecond time scale. The strength of the H-bond network involving Tyr22 (B10) and bound cyanide was tested at high pH. 3-Fluorotyrosine at position 22 had a pK(a) value at least 3 units higher than its intrinsic value, 8.5. In addition, evidence was found for long-range communication among the tyrosine sites. These observations demonstrated the utility of the 3-fluorotyrosine approach to gain insight in hemoglobin properties.
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Affiliation(s)
- Matthew P Pond
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
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27
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Abstract
Approximately, 20 years ago, a haemoglobin gene was identified within the genome of the cyanobacterium Nostoc commune. Haemoglobins have now been confirmed in multiple species of photosynthetic microbes beyond N. commune, and the diversity of these proteins has recently come under increased scrutiny. This chapter summarizes the state of knowledge concerning the phylogeny, physiology and chemistry of globins in cyanobacteria and green algae. Sequence information is by far the best developed and the most rapidly expanding aspect of the field. Structural and ligand-binding properties have been described for just a few proteins. Physiological data are available for even fewer. Although activities such as nitric oxide dioxygenation and oxygen scavenging are strong candidates for cellular function, dedicated studies will be required to complete the story on this intriguing and ancient group of proteins.
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28
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Abstract
Lactic acid bacteria (LAB) are of profound importance in food production and infection medicine. LAB do not rely on heme (protoheme IX) for growth and are unable to synthesize this cofactor but are generally able to assemble a small repertoire of heme-containing proteins if heme is provided from an exogenous source. These features are in contrast to other bacteria, which synthesize their heme or depend on heme for growth. We here present the cellular function of heme proteins so far identified in LAB and discuss their biogenesis as well as applications of the extraordinary heme physiology of LAB.
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29
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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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30
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Balsamo A, Sannino F, Merlino A, Parrilli E, Tutino ML, Mazzarella L, Vergara A. Role of the tertiary and quaternary structure in the formation of bis-histidyl adducts in cold-adapted hemoglobins. Biochimie 2012; 94:953-60. [DOI: 10.1016/j.biochi.2011.12.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 12/14/2011] [Indexed: 10/14/2022]
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31
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Kühl T, Sahoo N, Nikolajski M, Schlott B, Heinemann SH, Imhof D. Determination of hemin-binding characteristics of proteins by a combinatorial peptide library approach. Chembiochem 2011; 12:2846-55. [PMID: 22045633 DOI: 10.1002/cbic.201100556] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Indexed: 12/28/2022]
Abstract
Studies of the binding of heme/hemin to proteins or peptides have recently intensified as it became evident that heme serves not only as a prosthetic group, but also as a regulator and effector molecule interacting with transmembrane and cytoplasmic proteins. The iron-ion-containing heme group can associate with these proteins in different ways, with the amino acids Cys, His, and Tyr allowing individual modes of binding. Strong coordinate-covalent binding, such as in cytochrome c, is known, and reversible attachment is also discussed. Ligands for both types of binding have been reported independently, though sometimes with different affinities for similar sequences. We applied a combinatorial approach using the library (X)(4) (C/H/Y)(X)(4) to characterize peptide ligands with considerable hemin binding capacities. Some of the library-selected peptides were comparable in terms of hemin association independently of whether or not a cysteine residue was present in the sequence. Indeed, a preference for His-based (≈39 %) and Tyr-based (≈40 %) sequences over Cys-based ones (≈21 %) was detected. The binding affinities for the library-selected peptides, as determined by UV/Vis spectroscopy, were in the nanomolar range. Moreover, selected representatives efficiently competed for hemin binding with the human BK channel hSlo1, which is known to be regulated by heme through binding to its heme-binding domain.
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Affiliation(s)
- Toni Kühl
- Department of Biochemistry and Biophysics, Friedrich Schiller University of Jena, Hans-Knöll-Strasse 2, 07745 Jena, Germany
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32
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Merlino A, Howes BD, Prisco GD, Verde C, Smulevich G, Mazzarella L, Vergara A. Occurrence and formation of endogenous histidine hexa-coordination in cold-adapted hemoglobins. IUBMB Life 2011; 63:295-303. [PMID: 21491555 DOI: 10.1002/iub.446] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Accepted: 02/11/2011] [Indexed: 11/06/2022]
Abstract
Spectroscopic and crystallographic evidence of endogenous (His) ligation at the sixth coordination site of the heme iron has been reported for monomeric, dimeric, and tetrameric hemoglobins (Hbs) in both ferrous (hemochrome) and ferric (hemichrome) oxidation states. In particular, the ferric bis- histidyl adduct represents a common accessible ordered state for the β chains of all tetrameric Hbs isolated from Antarctic and sub-Antarctic fish. Indeed, the crystal structures of known tetrameric Hbs in the bis-His state are characterized by a different binding state of the α and β chains. An overall analysis of the bis-histidyl adduct of globin structures deposited in the Protein Data Bank reveals a marked difference between hemichromes in tetrameric Hbs compared to monomeric/dimeric Hbs. Herein, we review the structural, spectroscopic and stability features of hemichromes in tetrameric Antarctic fish Hbs. The role of bis-histidyl adducts is also addressed in a more evolutionary context alongside the concept of its potential physiological role.
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Affiliation(s)
- Antonello Merlino
- Department of Chemistry "Paolo Corradini," University of Naples "Federico II," Complesso Universitario Monte S. Angelo, Italy
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Chemical reactivity of Synechococcus sp. PCC 7002 and Synechocystis sp. PCC 6803 hemoglobins: covalent heme attachment and bishistidine coordination. J Biol Inorg Chem 2011; 16:539-52. [PMID: 21240532 DOI: 10.1007/s00775-011-0754-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 01/03/2011] [Indexed: 12/16/2022]
Abstract
In the absence of an exogenous ligand, the hemoglobins from the cyanobacteria Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7002 coordinate the heme group with two axial histidines (His46 and His70). These globins also form a covalent linkage between the heme 2-vinyl substituent and His117. The in vitro mechanism of heme attachment to His117 was examined with a combination of site-directed mutagenesis, NMR spectroscopy, and optical spectroscopy. The results supported an electrophilic addition with vinyl protonation being the rate-determining step. Replacement of His117 with a cysteine demonstrated that the reaction could occur with an alternative nucleophile. His46 (distal histidine) was implicated in the specificity of the reaction for the 2-vinyl group as well as protection of the protein from oxidative damage caused by exposure to exogenous H(2)O(2).
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34
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Pesce A, Nardini M, Labarre M, Richard C, Wittenberg JB, Wittenberg BA, Guertin M, Bolognesi M. Structural characterization of a group II 2/2 hemoglobin from the plant pathogen Agrobacterium tumefaciens. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1814:810-6. [PMID: 21070893 DOI: 10.1016/j.bbapap.2010.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 10/27/2010] [Accepted: 11/02/2010] [Indexed: 11/18/2022]
Abstract
Within the 2/2 hemoglobin sub-family, no group II 2/2Hbs from proteobacteria have been so far studied. Here we present the first structural characterization of a group II 2/2Hb from the soil and phytopathogenic bacterium Agrobacterium tumefaciens (At-2/2HbO). The crystal structure of ferric At-2/2HbO (reported at 2.1Å resolution) shows the location of specific/unique heme distal site residues (e.g., His(42)CD1, a residue distinctive of proteobacteria group II 2/2Hbs) that surround a heme-liganded water molecule. A highly intertwined hydrogen-bonded network, involving residues Tyr(26)B10, His(42)CD1, Ser(49)E7, Trp(93)G8, and three distal site water molecules, stabilizes the heme-bound ligand. Such a structural organization suggests a path for diatomic ligand diffusion to/from the heme. Neither a similar distal site structuring effect nor the presence of distal site water molecules has been so far observed in group I and group III 2/2Hbs, thus adding new distinctive information to the complex picture of currently available 2/2Hb structural and functional data. This article is part of a Special Issue entitled: Protein Structure and Function in the Crystalline State.
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Affiliation(s)
- Alessandra Pesce
- Department of Physics, University of Genova, I-16146 Genova, Italy
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35
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Structure and reactivity of hexacoordinate hemoglobins. Biophys Chem 2010; 152:1-14. [PMID: 20933319 DOI: 10.1016/j.bpc.2010.08.008] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 08/20/2010] [Accepted: 08/21/2010] [Indexed: 01/07/2023]
Abstract
The heme prosthetic group in hemoglobins is most often attached to the globin through coordination of either one or two histidine side chains. Those proteins with one histidine coordinating the heme iron are called "pentacoordinate" hemoglobins, a group represented by red blood cell hemoglobin and most other oxygen transporters. Those with two histidines are called "hexacoordinate hemoglobins", which have broad representation among eukaryotes. Coordination of the second histidine in hexacoordinate Hbs is reversible, allowing for binding of exogenous ligands like oxygen, carbon monoxide, and nitric oxide. Research over the past several years has produced a fairly detailed picture of the structure and biochemistry of hexacoordinate hemoglobins from several species including neuroglobin and cytoglobin in animals, and the nonsymbiotic hemoglobins in plants. However, a clear understanding of the physiological functions of these proteins remains an elusive goal.
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36
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Scott NL, Xu Y, Shen G, Vuletich DA, Falzone CJ, Li Z, Ludwig M, Pond MP, Preimesberger MR, Bryant DA, Lecomte JTJ. Functional and Structural Characterization of the 2/2 Hemoglobin from Synechococcus sp. PCC 7002,. Biochemistry 2010; 49:7000-11. [DOI: 10.1021/bi100463d] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Yu Xu
- Department of Biochemistry and Molecular Biology
| | | | | | | | - Zhongkui Li
- Department of Biochemistry and Molecular Biology
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37
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Pond MP, Vuletich DA, Falzone CJ, Majumdar A, Lecomte JTJ. (1)H, (15)N, and (13)C resonance assignments of the 2/2 hemoglobin from the cyanobacterium Synechococcus sp. PCC 7002 in the ferric bis-histidine state. BIOMOLECULAR NMR ASSIGNMENTS 2009; 3:211-214. [PMID: 19888693 DOI: 10.1007/s12104-009-9177-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Accepted: 06/11/2009] [Indexed: 05/28/2023]
Abstract
The hemoglobin from the cyanobacterium Synechococcus sp. PCC 7002 is a monomeric 123-residue Group I 2/2 hemoglobin. Here, we report (1)H, (15)N, and (13)C assignments for the ferric (low-spin, S = (1/2)) protein with a b heme cofactor and after post-translational modification leading to a c-like heme.
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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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38
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Verde C, Giordano D, Russo R, Riccio A, Vergara A, Mazzarella L, di Prisco G. Hemoproteins in the cold. Mar Genomics 2009; 2:67-73. [DOI: 10.1016/j.margen.2009.03.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Revised: 01/16/2009] [Accepted: 03/02/2009] [Indexed: 11/25/2022]
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39
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Pesce A, Thijs L, Nardini M, Desmet F, Sisinni L, Gourlay L, Bolli A, Coletta M, Van Doorslaer S, Wan X, Alam M, Ascenzi P, Moens L, Bolognesi M, Dewilde S. HisE11 and HisF8 provide bis-histidyl heme hexa-coordination in the globin domain of Geobacter sulfurreducens globin-coupled sensor. J Mol Biol 2008; 386:246-60. [PMID: 19109973 DOI: 10.1016/j.jmb.2008.12.023] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Revised: 12/05/2008] [Accepted: 12/09/2008] [Indexed: 02/08/2023]
Abstract
Among heme-based sensors, recent phylogenomic and sequence analyses have identified 34 globin coupled sensors (GCS), to which an aerotactic or gene-regulating function has been tentatively ascribed. Here, the structural and biochemical characterization of the globin domain of the GCS from Geobacter sulfurreducens (GsGCS(162)) is reported. A combination of X-ray crystallography (crystal structure at 1.5 A resolution), UV-vis and resonance Raman spectroscopy reveals the ferric GsGCS(162) as an example of bis-histidyl hexa-coordinated GCS. In contrast to the known hexa-coordinated globins, the distal heme-coordination in ferric GsGCS(162) is provided by a His residue unexpectedly located at the E11 topological site. Furthermore, UV-vis and resonance Raman spectroscopy indicated that ferrous deoxygenated GsGCS(162) is a penta-/hexa-coordinated mixture, and the heme hexa-to-penta-coordination transition does not represent a rate-limiting step for carbonylation kinetics. Lastly, electron paramagnetic resonance indicates that ferrous nitrosylated GsGCS(162) is a penta-coordinated species, where the proximal HisF8-Fe bond is severed.
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Affiliation(s)
- Alessandra Pesce
- Department of Physics, CNISM and Center for Excellence in Biomedical Research, University of Genova, Via Dodecaneso, 33, I-16146 Genova, Italy
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40
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Smagghe BJ, Trent JT, Hargrove MS. NO dioxygenase activity in hemoglobins is ubiquitous in vitro, but limited by reduction in vivo. PLoS One 2008; 3:e2039. [PMID: 18446211 PMCID: PMC2323109 DOI: 10.1371/journal.pone.0002039] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2008] [Accepted: 02/03/2008] [Indexed: 12/02/2022] Open
Abstract
Genomics has produced hundreds of new hemoglobin sequences with examples in nearly every living organism. Structural and biochemical characterizations of many recombinant proteins reveal reactions, like oxygen binding and NO dioxygenation, that appear general to the hemoglobin superfamily regardless of whether they are related to physiological function. Despite considerable attention to “hexacoordinate” hemoglobins, which are found in nearly every plant and animal, no clear physiological role(s) has been assigned to them in any species. One popular and relevant hypothesis for their function is protection against NO. Here we have tested a comprehensive representation of hexacoordinate hemoglobins from plants (rice hemoglobin), animals (neuroglobin and cytoglobin), and bacteria (Synechocystis hemoglobin) for their abilities to scavenge NO compared to myoglobin. Our experiments include in vitro comparisons of NO dioxygenation, ferric NO binding, NO-induced reduction, NO scavenging with an artificial reduction system, and the ability to substitute for a known NO scavenger (flavohemoglobin) in E. coli. We conclude that none of these tests reveal any distinguishing predisposition toward a role in NO scavenging for the hxHbs, but that any hemoglobin could likely serve this role in the presence of a mechanism for heme iron re-reduction. Hence, future research to test the role of Hbs in NO scavenging would benefit more from the identification of cognate reductases than from in vitro analysis of NO and O2 binding.
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Affiliation(s)
- Benoit J. Smagghe
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
| | - James T. Trent
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
| | - Mark S. Hargrove
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
- * E-mail:
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41
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Metcalfe C, Daltrop O, Ferguson S, Raven E. Tuning the formation of a covalent haem-protein link by selection of reductive or oxidative conditions as exemplified by ascorbate peroxidase. Biochem J 2008; 408:355-61. [PMID: 17714075 PMCID: PMC2267360 DOI: 10.1042/bj20071041] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Previous work [Metcalfe, Ott, Patel, Singh, Mistry, Goff and Raven (2004) J. Am. Chem. Soc. 126, 16242-16248] has shown that the introduction of a methionine residue (S160M variant) close to the 2-vinyl group of the haem in ascorbate peroxidase leads to the formation of a covalent haem-methionine linkage under oxidative conditions (i.e. on reaction with H2O2). In the present study, spectroscopic, HPLC and mass spectrometric evidence is presented to show that covalent attachment of the haem to an engineered cysteine residue can also occur in the S160C variant, but, in this case, under reducing conditions analogous to those used in the formation of covalent links in cytochrome c. The data add an extra dimension to our understanding of haem to protein covalent bond formation because they show that different types of covalent attachment (one requiring an oxidative mechanism, the other a reductive pathway) are both accessible within same protein architecture.
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Affiliation(s)
- Clive L. Metcalfe
- *Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, U.K
| | - Oliver Daltrop
- †Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K
| | - Stuart J. Ferguson
- †Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K
- Correspondence may be addressed to either of these authors (email or )
| | - Emma Lloyd Raven
- *Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, U.K
- Correspondence may be addressed to either of these authors (email or )
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42
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Pesce A, Milani M, Nardini M, Bolognesi M. Mapping Heme‐Ligand Tunnels in Group I Truncated(2/2) Hemoglobins. Methods Enzymol 2008; 436:303-15. [DOI: 10.1016/s0076-6879(08)36017-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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43
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Vergara A, Vitagliano L, Verde C, di Prisco G, Mazzarella L. Spectroscopic and crystallographic characterization of bis-histidyl adducts in tetrameric hemoglobins. Methods Enzymol 2008; 436:425-44. [PMID: 18237647 DOI: 10.1016/s0076-6879(08)36024-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Hemoglobins (Hbs) are important proteins devoted to oxygen transport. Hbs carry out their function by keeping the iron atom, which binds the oxygen molecule, in its reduced Fe(II) state. Nonetheless, it is well known that Hbs frequently undergo, even under physiological conditions, spontaneous oxidation. Although these processes have been widely investigated, their role and impact in different biological contexts are still highly debated. In vertebrate Hbs, assembled in alpha2beta2 tetramers, it has traditionally been assumed that oxidized forms endowed with nativelike structures are either aquo-met or hydroxy-met states, depending on the pH of the medium. This view has been questioned by several independent investigations. In the past, indirect evidence of the existence of alternative nativelike oxidized forms was obtained from spectroscopic analyses. Indeed, it was suggested that, in tetrameric Hbs, bis-histidyl hemichrome states could be compatible with folded structures. Recent studies performed by complementing spectroscopic and crystallographic methodologies have provided a detailed picture of hemichrome structure and formation in these proteins. Here we review the methodological approaches adopted to achieve these results, the main structural features of these states, and the current hypotheses on their possible functional implications.
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Affiliation(s)
- Alessandro Vergara
- Department of Chemistry and Consorzio Bioteknet, University of Naples Federico II, Naples, Italy
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44
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Hoy JA, Robinson H, Trent JT, Kakar S, Smagghe BJ, Hargrove MS. Plant hemoglobins: a molecular fossil record for the evolution of oxygen transport. J Mol Biol 2007; 371:168-79. [PMID: 17560601 DOI: 10.1016/j.jmb.2007.05.029] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Revised: 05/07/2007] [Accepted: 05/09/2007] [Indexed: 10/23/2022]
Abstract
The evolution of oxygen transport hemoglobins occurred on at least two independent occasions. The earliest event led to myoglobin and red blood cell hemoglobin in animals. In plants, oxygen transport "leghemoglobins" evolved much more recently. In both events, pentacoordinate heme sites capable of inert oxygen transfer evolved from hexacoordinate hemoglobins that have unrelated functions. High sequence homology between hexacoordinate and pentacoordinate hemoglobins in plants has poised them for potential structural analysis leading to a molecular understanding of this important evolutionary event. However, the lack of a plant hexacoordinate hemoglobin structure in the exogenously ligand-bound form has prevented such comparison. Here we report the crystal structure of the cyanide-bound hexacoordinate hemoglobin from barley. This presents the first opportunity to examine conformational changes in plant hexacoordinate hemoglobins upon exogenous ligand binding, and reveals structural mechanisms for stabilizing the high-energy pentacoordinate heme conformation critical to the evolution of reversible oxygen binding hemoglobins.
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Affiliation(s)
- Julie A Hoy
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA
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45
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Hoy JA, Smagghe BJ, Halder P, Hargrove MS. Covalent heme attachment in Synechocystis hemoglobin is required to prevent ferrous heme dissociation. Protein Sci 2007; 16:250-60. [PMID: 17242429 PMCID: PMC2203299 DOI: 10.1110/ps.062572607] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Synechocystis hemoglobin contains an unprecedented covalent bond between a nonaxial histidine side chain (H117) and the heme 2-vinyl. This bond has been previously shown to stabilize the ferric protein against denaturation, and also to affect the kinetics of cyanide association. However, it is unclear why Synechocystis hemoglobin would require the additional degree of stabilization accompanying the His117-heme 2-vinyl bond because it also displays endogenous bis-histidyl axial heme coordination, which should greatly assist heme retention. Furthermore, the mechanism by which the His117-heme 2-vinyl bond affects ligand binding has not been reported, nor has any investigation of the role of this bond on the structure and function of the protein in the ferrous oxidation state. Here we report an investigation of the role of the Synechocystis hemoglobin His117-heme 2-vinyl bond on structure, heme coordination, exogenous ligand binding, and stability in both the ferrous and ferric oxidation states. Our results reveal that hexacoordinate Synechocystis hemoglobin lacking this bond is less stable in the ferrous oxidation state than the ferric, which is surprising in light of our understanding of pentacoordinate Hb stability, in which the ferric protein is always less stable. It is also demonstrated that removal of the His117-heme 2-vinyl bond increases the affinity constant for intramolecular histidine coordination in the ferric oxidation state, thus presenting greater competition for the ligand binding site and lowering the observed rate and affinity constants for exogenous ligands.
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Affiliation(s)
- Julie A Hoy
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA
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46
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Vergara A, Franzese M, Merlino A, Vitagliano L, Verde C, di Prisco G, Lee HC, Peisach J, Mazzarella L. Structural characterization of ferric hemoglobins from three antarctic fish species of the suborder notothenioidei. Biophys J 2007; 93:2822-9. [PMID: 17545238 PMCID: PMC1989692 DOI: 10.1529/biophysj.107.105700] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Spontaneous autoxidation of tetrameric Hbs leads to the formation of Fe (III) forms, whose physiological role is not fully understood. Here we report structural characterization by EPR of the oxidized states of tetrameric Hbs isolated from the Antarctic fish species Trematomus bernacchii, Trematomus newnesi, and Gymnodraco acuticeps, as well as the x-ray crystal structure of oxidized Trematomus bernacchii Hb, redetermined at high resolution. The oxidation of these Hbs leads to formation of states that were not usually detected in previous analyses of tetrameric Hbs. In addition to the commonly found aquo-met and hydroxy-met species, EPR analyses show that two distinct hemichromes coexist at physiological pH, referred to as hemichromes I and II, respectively. Together with the high-resolution crystal structure (1.5 A) of T. bernacchii and a survey of data available for other heme proteins, hemichrome I was assigned by x-ray crystallography and by EPR as a bis-His complex with a distorted geometry, whereas hemichrome II is a less constrained (cytochrome b5-like) bis-His complex. In four of the five Antartic fish Hbs examined, hemichrome I is the major form. EPR shows that for HbCTn, the amount of hemichrome I is substantially reduced. In addition, the concomitant presence of a penta-coordinated high-spin Fe (III) species, to our knowledge never reported before for a wild-type tetrameric Hb, was detected. A molecular modeling investigation demonstrates that the presence of the bulkier Ile in position 67beta in HbCTn in place of Val as in the other four Hbs impairs the formation of hemichrome I, thus favoring the formation of the ferric penta-coordinated species. Altogether the data show that ferric states commonly associated with monomeric and dimeric Hbs are also found in tetrameric Hbs.
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Affiliation(s)
- Alessandro Vergara
- Department of Chemistry, University of Naples Federico II, Complesso Universitario Monte S. Angelo, I-80126 Naples, Italy
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47
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Nardini M, Pesce A, Milani M, Bolognesi M. Protein fold and structure in the truncated (2/2) globin family. Gene 2007; 398:2-11. [PMID: 17532150 DOI: 10.1016/j.gene.2007.02.045] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Revised: 02/02/2007] [Accepted: 02/13/2007] [Indexed: 10/23/2022]
Abstract
Analysis of amino acids sequences and protein folds has recently unraveled the structural bases and details of several proteins from the recently discovered "truncated hemoglobin" family. The analysis here presented, in agreement with previous surveys, shows that truncated hemoglobins can be classified in three main groups, based on their structural properties. Crystallographic analyses have shown that all three groups adopt a 2-on-2 alpha-helical sandwich fold, resulting from apparent editing of the classical 3-on-3 alpha-helical sandwich of vertebrate and invertebrate conventional globins. Specific structural features distinguish each of the three groups. Among these, a protein matrix tunnel system is typical of group I, a Trp residue at the G8 topological site is conserved in groups II and III, and TyrB10 is almost invariant through the three groups. A strongly intertwined network of hydrogen bonds stabilizes the heme bound ligand, despite variability of the heme distal residues observed in the different proteins considered. Details of ligand recognition in the three groups are discussed at the light of residue conservation and of differing ligand diffusion pathways to the heme. Based on structural analyses of the family-specific fold, we endorse a recent proposal of leaving the "truncated hemoglobins" term, that does not represent properly the observed 2-on-2 alpha-helical sandwich fold, and adopting the simple "2/2Hb" term to concisely address this protein family.
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Affiliation(s)
- Marco Nardini
- Department of Biomolecular Sciences and Biotechnology, CNR-INFM, University of Milano, Via Celoria 26, I-20131 Milano, Italy
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48
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Ascenzi P, Bolognesi M, Milani M, Guertin M, Visca P. Mycobacterial truncated hemoglobins: from genes to functions. Gene 2007; 398:42-51. [PMID: 17532149 DOI: 10.1016/j.gene.2007.02.043] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2006] [Revised: 01/29/2007] [Accepted: 02/13/2007] [Indexed: 10/23/2022]
Abstract
Infections caused by bacteria belonging to genus Mycobacterium are among the most challenging threats for human health. The ability of mycobacteria to persist in vivo in the presence of reactive nitrogen and oxygen species implies the presence in these bacteria of effective detoxification mechanisms. Mycobacterial truncated hemoglobins (trHbs) have recently been implicated in scavenging of reactive nitrogen species. Individual members from each trHb family (N, O, and P) can be present in the same mycobacterial species. The distinct features of the heme active site structure combined with different ligand binding properties and in vivo expression patterns of mycobacterial trHbs suggest that these globins may accomplish diverse functions. Here, recent genomic, structural and biochemical information on mycobacterial trHbs is reviewed, with the aim of providing further insights into the role of these globins in mycobacterial physiology.
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Affiliation(s)
- Paolo Ascenzi
- National Institute for Infectious Diseases I.R.C.C.S. Lazzaro Spallanzani, Via Portuense 292, I-00149 Roma, Italy.
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49
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Knappenberger JA, Kuriakose SA, Vu BC, Nothnagel HJ, Vuletich DA, Lecomte JT. Proximal influences in two-on-two globins: effect of the Ala69Ser replacement on Synechocystis sp. PCC 6803 hemoglobin. Biochemistry 2006; 45:11401-13. [PMID: 16981700 PMCID: PMC2533430 DOI: 10.1021/bi060691x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The cyanobacterium Synechocystis sp. PCC 6803 (S6803) expresses a two-on-two globin in which His46 (distal side) and His70 (proximal) function as heme iron axial ligands. His46 can be displaced by O2, CO, and CN-, among others, whereas His70 is not labile under native conditions. The residue preceding the proximal histidine has been implicated in controlling globin axial ligand reactivity; the details of the mechanism, however, are not well understood, and little information exists for bis-histidyl hexacoordinate proteins. In many vertebrate hemoglobins and in the Synechocystis protein, the position is occupied by an alanine, whereas, in myoglobins, it is a serine involved in an intricate hydrogen-bond network. We examined the role of Ala69 in S6803 hemoglobin through the effects of an Ala --> Ser replacement. The substitution resulted in minor structural perturbations, but the response of the holoprotein to temperature-, urea-, and acid-induced denaturation was measurably affected. Enhanced three-state behavior was manifested in the decoupling of heme binding and secondary-structure formation. Urea-gradient gel experiments revealed that the stability of the apoprotein was unchanged by the replacement and that a slight alteration of the folding kinetics occurred in the holoproteins. Cyanide-binding experiments were performed to assess trans effects. The apparent rate constant for association decreased 2-fold upon Ala69Ser replacement. This deceleration was attributed to a change in the lifetime of a state containing a decoordinated His46. The results demonstrated that, as in vertebrate globins and leghemoglobin, proximal influences operate to determine fundamental dynamic and thermodynamic properties of the protein.
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50
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Bondarenko V, Dewilde S, Moens L, La Mar GN. Solution 1H NMR characterization of the axial bonding of the two His in oxidized human cytoglobin. J Am Chem Soc 2006; 128:12988-99. [PMID: 17002396 PMCID: PMC2566969 DOI: 10.1021/ja063330d] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Solution 1H NMR spectroscopy has been used to determine the relative strengths (covalency) of the two axial His-Fe bonds in paramagnetic, S = 1/2, human met-cytoglobin. The sequence specific assignments of crucial portions of the proximal and distal helices, together with the magnitude of hyperfine shifts and paramagnetic relaxation, establish that His81 and His113, at the canonical positions E7 and F8 in the myoglobin fold, respectively, are ligated to the iron. The characterized complex (approximately 90%) in solution has protohemin oriented as in crystals, with the remaining approximately 10% exhibiting the hemin orientation rotated 180 degrees about the alpha-, gamma-meso axis. No evidence could be obtained for any five-coordinate complex (<1%) in equilibrium with the six-coordinate complexes. Extensive sequence-specific assignments on other dipolar shifted helical fragments and loops, together with available alternate crystal coordinates for the complex, allowed the robust determination of the orientation and anisotropies of the paramagnetic susceptibility tensor. The tilt of the major axis is controlled by the His-Fe-His vector, and the rhombic axes are controlled by the mean of the imidazole orientations for the two His. The anisotropy of the paramagnetic susceptibility tensor allowed the quantitative factoring of the hyperfine shifts for the two axial His to reveal an indistinguishable pattern and magnitudes of the contact shifts or pi spin densities, and hence, indistinguishable Fe-imidazole covalency for both Fe-His bonds.
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Affiliation(s)
- Vasyl Bondarenko
- Department of Chemistry, University of California, Davis, CA 95616
| | - Sylvia Dewilde
- Department of Biomedical Sciences, University of Belgium, Universiteitsplein 1, B-2610 Wilrijk (Anterwerpen) Belgium
| | - Luc Moens
- Department of Biomedical Sciences, University of Belgium, Universiteitsplein 1, B-2610 Wilrijk (Anterwerpen) Belgium
| | - Gerd N. La Mar
- Department of Chemistry, University of California, Davis, CA 95616
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