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Detzel MS, Schmalohr BF, Steinbock F, Hopp MT, Ramoji A, Paul George AA, Neugebauer U, Imhof D. Revisiting the interaction of heme with hemopexin. Biol Chem 2021; 402:675-691. [PMID: 33581700 DOI: 10.1515/hsz-2020-0347] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 02/06/2021] [Indexed: 12/23/2022]
Abstract
In hemolytic disorders, erythrocyte lysis results in massive release of hemoglobin and, subsequently, toxic heme. Hemopexin is the major protective factor against heme toxicity in human blood and currently considered for therapeutic use. It has been widely accepted that hemopexin binds heme with extraordinarily high affinity of <1 pM in a 1:1 ratio. However, several lines of evidence point to a higher stoichiometry and lower affinity than determined 50 years ago. Here, we re-analyzed these data. SPR and UV/Vis spectroscopy were used to monitor the interaction of heme with the human protein. The heme-binding sites of hemopexin were characterized using hemopexin-derived peptide models and competitive displacement assays. We obtained a K D value of 0.32 ± 0.04 nM and the ratio for the interaction was determined to be 1:1 at low heme concentrations and at least 2:1 (heme:hemopexin) at high concentrations. We were able to identify two yet unknown potential heme-binding sites on hemopexin. Furthermore, molecular modelling with a newly created homology model of human hemopexin suggested a possible recruiting mechanism by which heme could consecutively bind several histidine residues on its way into the binding pocket. Our findings have direct implications for the potential administration of hemopexin in hemolytic disorders.
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Affiliation(s)
- Milena Sophie Detzel
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, D-53121Bonn, Germany
| | - Benjamin Franz Schmalohr
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, D-53121Bonn, Germany
| | - Francèl Steinbock
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, D-53121Bonn, Germany
| | - Marie-Thérèse Hopp
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, D-53121Bonn, Germany
| | - Anuradha Ramoji
- Center for Sepsis Control and Care (CSCC), Jena University Hospital, D-07747Jena, Germany.,Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, D-07745Jena, Germany
| | - Ajay Abisheck Paul George
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, D-53121Bonn, Germany
| | - Ute Neugebauer
- Center for Sepsis Control and Care (CSCC), Jena University Hospital, D-07747Jena, Germany.,Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, D-07745Jena, Germany
| | - Diana Imhof
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, D-53121Bonn, Germany
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Abstract
A large number of different enzyme immobilization techniques are used in the field of life sciences, clinical diagnostics, or biotechnology. Most of them are based on a chemically mediated formation of covalent bond between an enzyme and support material. The covalent bond formation is usually associated with changes of the enzymes’ three-dimensional structure that can lead to reduction of enzyme activity. The present work demonstrates a potential of an ambient ion-landing technique to effectively immobilize enzymes on conductive supports for direct matrix-assisted laser desorption/ionization (MALDI) mass spectrometry analyses of reaction products. Ambient ion landing is an electrospray-based technique allowing strong and stable noncovalent and nondestructive enzyme deposition onto conductive supports. Three serine proteolytic enzymes including trypsin, α-chymotrypsin, and subtilisin A were immobilized onto conductive indium tin oxide glass slides compatible with MALDI mass spectrometry. The functionalized MALDI chips were used for in situ time-limited proteolysis of proteins and protein–ligand complexes to monitor their structural changes under different conditions. The data from limited proteolysis using MALDI chips fits to known or predicted protein structures. The results show that functionalized MALDI chips are sensitive, robust, and fast and might be automated for general use in the field of structural biology.
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Samhan-Arias AK, Cordas CM, Carepo MS, Maia LB, Gutierrez-Merino C, Moura I, Moura JJG. Ligand accessibility to heme cytochrome b 5 coordinating sphere and enzymatic activity enhancement upon tyrosine ionization. J Biol Inorg Chem 2019; 24:317-330. [PMID: 30838452 DOI: 10.1007/s00775-019-01649-2] [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: 08/26/2018] [Accepted: 02/21/2019] [Indexed: 01/21/2023]
Abstract
Recently, we observed that at extreme alkaline pH, cytochrome b5 (Cb5) acquires a peroxidase-like activity upon formation of a low spin hemichrome associated with a non-native state. A functional characterization of Cb5, in a wide pH range, shows that oxygenase/peroxidase activities are stimulated in alkaline media, and a correlation between tyrosine ionization and the attained enzymatic activities was noticed, associated with an altered heme spin state, when compared to acidic pH values at which the heme group is released. In these conditions, a competitive assay between imidazole binding and Cb5 endogenous heme ligands revealed the appearance of a binding site for this exogenous ligand that promotes a heme group exposure to the solvent upon ligation. Our results shed light on the mechanism behind Cb5 oxygenase/peroxidase activity stimulation in alkaline media and reveal a role of tyrosinate anion enhancing Cb5 enzymatic activities on the distorted protein before maximum protein unfolding.
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Affiliation(s)
- Alejandro K Samhan-Arias
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Lisbon, Portugal.
| | - Cristina M Cordas
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Lisbon, Portugal
| | - Marta S Carepo
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Lisbon, Portugal
| | - Luisa B Maia
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Lisbon, Portugal
| | - Carlos Gutierrez-Merino
- Department of Biochemistry and Molecular Biology, Faculty of Sciences and Institute of Molecular Pathology Biomarkers, University of Extremadura, 06006, Badajoz, Spain
| | - Isabel Moura
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Lisbon, Portugal
| | - José J G Moura
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Lisbon, Portugal.
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Ikushiro H, Nagami A, Takai T, Sawai T, Shimeno Y, Hori H, Miyahara I, Kamiya N, Yano T. Heme-dependent Inactivation of 5-Aminolevulinate Synthase from Caulobacter crescentus. Sci Rep 2018; 8:14228. [PMID: 30242198 PMCID: PMC6154995 DOI: 10.1038/s41598-018-32591-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 09/11/2018] [Indexed: 11/09/2022] Open
Abstract
The biosynthesis of heme is strictly regulated, probably because of the toxic effects of excess heme and its biosynthetic precursors. In many organisms, heme biosynthesis starts with the production of 5-aminolevulinic acid (ALA) from glycine and succinyl-coenzyme A, a process catalyzed by a homodimeric enzyme, pyridoxal 5′-phosphate (PLP)-dependent 5-aminolevulinate synthase (ALAS). ALAS activity is negatively regulated by heme in various ways, such as the repression of ALAS gene expression, degradation of ALAS mRNA, and inhibition of mitochondrial translocation of the mammalian precursor protein. There has been no clear evidence, however, that heme directly binds to ALAS to negatively regulate its activity. We found that recombinant ALAS from Caulobacter crescentus was inactivated via a heme-mediated feedback manner, in which the essential coenzyme PLP was rel eased to form the inactive heme-bound enzyme. The spectroscopic properties of the heme-bound ALAS showed that a histidine-thiolate hexa-coordinated ferric heme bound to each subunit with a one-to-one stoichiometry. His340 and Cys398 were identified as the axial ligands of heme, and mutant ALASs lacking either of these ligands became resistant to heme-mediated inhibition. ALAS expressed in C. crescentus was also found to bind heme, suggesting that heme-mediated feedback inhibition of ALAS is physiologically relevant in C. crescentus.
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Affiliation(s)
- Hiroko Ikushiro
- Department of Biochemistry, Faculty of Medicine, Osaka Medical College, Osaka, 569-8686, Japan.
| | - Atsushi Nagami
- Department of Chemistry, Graduate School of Science, Osaka City University, Osaka, 558-8585, Japan
| | - Tomoko Takai
- Department of Biochemistry, Faculty of Medicine, Osaka Medical College, Osaka, 569-8686, Japan.,Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan
| | - Taiki Sawai
- Department of Biochemistry, Faculty of Medicine, Osaka Medical College, Osaka, 569-8686, Japan
| | - Yuki Shimeno
- Department of Chemistry, Graduate School of Science, Osaka City University, Osaka, 558-8585, Japan
| | - Hiroshi Hori
- Department of Chemistry, Graduate School of Science, Kobe University, Kobe, 657-8501, Japan
| | - Ikuko Miyahara
- Department of Chemistry, Graduate School of Science, Osaka City University, Osaka, 558-8585, Japan
| | - Nobuo Kamiya
- Department of Chemistry, Graduate School of Science, Osaka City University, Osaka, 558-8585, Japan.,The OCU Advanced Research Institute for Natural Science and Technology (OCARINA), Osaka City University, Osaka, 558-8585, Japan
| | - Takato Yano
- Department of Biochemistry, Faculty of Medicine, Osaka Medical College, Osaka, 569-8686, Japan.
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Preparation of a biologically active apo-cytochrome b5 via heterologous expression in Escherichia coli. Protein Expr Purif 2009; 66:203-9. [PMID: 19358889 DOI: 10.1016/j.pep.2009.03.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Revised: 03/30/2009] [Accepted: 03/30/2009] [Indexed: 11/23/2022]
Abstract
Cytochrome b(5) (b(5)) has been shown to modulate many cytochrome P450 (CYP)-dependent reactions. In order to elucidate the mechanism of such modulations, it is necessary to evaluate not only the effect of native b(5) on CYP-catalyzed reactions, but also that of the apo-cytochrome b(5) (apo-b(5)). Therefore, the apo-b(5) protein was prepared using a heterologous expression in Escherichia coli. The gene for rabbit b(5) was constructed from synthetic oligonucleotides using polymerase chain reaction (PCR), cloned into pUC19 plasmid and amplified in DH5 alpha cells. The gene sequence was verified by DNA sequencing. The sequence coding b(5) was cleaved from pUC19 by NdeI and XhoI restriction endonucleases and subcloned to the expression vector pET22b. This vector was used to transform E. coli BL-21 (DE3) Gold cells by heat shock. Expression of b(5) was induced with isopropyl beta-D-1-thiogalactopyranoside (IPTG). The b(5) protein, produced predominantly in its apo-form, was purified from isolated membranes of E. coli cells by chromatography on a column of DEAE-Sepharose. Using such procedures, the homogenous preparation of apo-b(5) protein was obtained. Oxidized and reduced forms of the apo-b(5) reconstituted with heme exhibit the same absorbance spectra as native b(5). The prepared recombinant apo-b(5) reconstituted with heme can be reduced by NADPH:CYP reductase. The reconstituted apo-b(5) is also fully biologically active, exhibiting the comparable stimulation effect on the CYP3A4 enzymatic activity towards oxidation of 1-phenylazo-2-hydroxynaphthalene (Sudan I) as native rabbit and human b(5).
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