1
|
Schertenleib T, Karve VV, Stoian D, Asgari M, Trukhina O, Oveisi E, Mensi M, Queen WL. A post-synthetic modification strategy for enhancing Pt adsorption efficiency in MOF/polymer composites. Chem Sci 2024; 15:8323-8333. [PMID: 38846398 PMCID: PMC11151820 DOI: 10.1039/d4sc00174e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 04/26/2024] [Indexed: 06/09/2024] Open
Abstract
Growing polymers inside porous metal-organic frameworks (MOFs) can allow incoming guests to access the backbone of otherwise non-porous polymers, boosting the number and/or strength of available adsorption sites inside the porous support. In the present work, we have devised a novel post-synthetic modification (PSM) strategy that allows one to graft metal-chelating functionality onto a polymer backbone while inside MOF pores, enhancing the material's ability to recover Pt(iv) from complex liquids. For this, polydopamine (PDA) was first grown inside of a MOF, known as Fe-BTC (or MIL-100 Fe). Next, a small thiol-containing molecule, 2,3-dimercapto-1-propanol (DIP), was grafted to the PDA via a Michael addition. After the modification of the PDA, the Pt adsorption capacity and selectivity were greatly enhanced, particularly in the low concentration regime, due to the high affinity of the thiols towards Pt. Moreover, the modified composite was found to be highly selective for precious metals (Pt, Pd, and Au) over common base metals found in electronic waste (i.e., Pb, Cu, Ni, and Zn). X-ray photoelectron spectroscopy (XPS) and in situ X-ray absorption spectroscopy (XAS) provided insight into the Pt adsorption/reduction process. Last, the PSM was extended to various thiols to demonstrate the versatility of the chemistry. It is hoped that this work will open pathways for the future design of novel adsorbents that are fine-tuned for the rapid, selective retrieval of high-value and/or critical metals from complex liquids.
Collapse
Affiliation(s)
- Till Schertenleib
- Institute of Chemical Science and Engineering (ISIC), École Polytechnique Fédérale de Lausanne (EPFL) Rue de l'industrie 17 1951 Sion Switzerland
| | - Vikram V Karve
- Institute of Chemical Science and Engineering (ISIC), École Polytechnique Fédérale de Lausanne (EPFL) Rue de l'industrie 17 1951 Sion Switzerland
| | - Dragos Stoian
- Swiss-Norwegian Beamlines, European Synchrotron Research Facilities (ESRF) BP 220 Grenoble France
| | - Mehrdad Asgari
- Institute of Chemical Science and Engineering (ISIC), École Polytechnique Fédérale de Lausanne (EPFL) Rue de l'industrie 17 1951 Sion Switzerland
- Department of Chemical Engineering and Biotechnology, University of Cambridge CB3 0AS Cambridge UK
| | - Olga Trukhina
- Institute of Chemical Science and Engineering (ISIC), École Polytechnique Fédérale de Lausanne (EPFL) Rue de l'industrie 17 1951 Sion Switzerland
| | - Emad Oveisi
- Interdisciplinary Center for Electron Microscopy, École Polytechnique Fédérale de Lausanne (EPFL) CH-1015 Lausanne Switzerland
| | - Mounir Mensi
- Institute of Chemical Science and Engineering (ISIC), École Polytechnique Fédérale de Lausanne (EPFL) Rue de l'industrie 17 1951 Sion Switzerland
| | - Wendy L Queen
- Institute of Chemical Science and Engineering (ISIC), École Polytechnique Fédérale de Lausanne (EPFL) Rue de l'industrie 17 1951 Sion Switzerland
| |
Collapse
|
2
|
Bhatt A, Mukhopadhyaya A, Ali ME. α-Helix in Cystathionine β-Synthase Enzyme Acts as an Electron Reservoir. J Phys Chem B 2022; 126:4754-4760. [PMID: 35687358 DOI: 10.1021/acs.jpcb.2c01657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The modulation of electron density at the Pyridoxal 5'-phosphate (PLP) catalytic center, because of charge transfer across the α-helix/PLP interface, is the determining factor for the enzymatic activities in the human Cystathionine β-Synthase (hCBS) enzyme. Applying density functional theory calculations, in conjunction with the real space density analysis, we investigated the charge density delocalization across the entire heme-α-helix-PLP electron communication channels. The electron delocalization due to hydrogen bonds at the heme/α-helix and α-helix/PLP interfaces are found to be extended over a very long range, as a result of redistribution of electron densities of the cofactors. Moreover, the internal hydrogen bonds of α-helix that are crucial for its secondary structure also participate in the electron redistribution through the structured hydrogen-bond network. α-Helix is found to accumulate the electron density at the ground state from both of the cofactors and behaves as an electron reservoir for catalytic reaction at the electrophilic center of PLP.
Collapse
Affiliation(s)
- Aashish Bhatt
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab-140306, India
| | - Aritra Mukhopadhyaya
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab-140306, India
| | - Md Ehesan Ali
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab-140306, India
| |
Collapse
|
3
|
Structural perspectives on H 2S homeostasis. Curr Opin Struct Biol 2021; 71:27-35. [PMID: 34214926 DOI: 10.1016/j.sbi.2021.05.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 05/05/2021] [Accepted: 05/23/2021] [Indexed: 11/21/2022]
Abstract
The enzymes involved in H2S homeostasis regulate its production from sulfur-containing amino acids and its oxidation to thiosulfate and sulfate. Two gatekeepers in this homeostatic circuit are cystathionine beta-synthase, which commits homocysteine to cysteine, and sulfide quinone oxidoreductase, which commits H2S to oxidation via a mitochondrial pathway. Inborn errors at either locus affect sulfur metabolism, increasing homocysteine-derived H2S synthesis in the case of CBS deficiency and reducing complex IV activity in the case of SQOR deficiency. In this review, we focus on structural perspectives on the reaction mechanisms and regulation of these two enzymes, which are key to understanding H2S homeostasis in health and its dysregulation and potential targeting in disease.
Collapse
|
4
|
Zuccarello L, Berthomieu C, Boussac A, Brubach JB, Díaz-Moreno I, Díaz Quintana AJ, Hienerwadel R. Protonation of the Cysteine Axial Ligand Investigated in His/Cys c-Type Cytochrome by UV-Vis and Mid- and Far-IR Spectroscopy. J Phys Chem Lett 2020; 11:4198-4205. [PMID: 32364390 DOI: 10.1021/acs.jpclett.0c01016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
His/Cys coordination was recently found in several c-type cytochromes, which could act as sensors, in electron transport or in regulation. Toward a better understanding of Cys function and reactivity in these cytochromes, we compare cytochrome c6 (c6wt) from the cyanobacterium Nostoc PCC 7120 with its Met58Cys mutant. We probe the axial ligands and heme properties by combining visible and mid- to far-FTIR difference spectroscopies. Cys58 determines the strong negative redox potential and pH dependence of M58C (EmM58C = -375 mV, versus Emc6wt = +339 mV). Mid-IR (notably Cys ν(SH), His ν(C5N1), heme δ(CmH)) and far-IR (ν(Fe(II)-His), ν(His-Fe(III)-Cys)) markers of the heme and ligands show that Cys58 remains a strong thiolate ligand of reduced Met58Cys at alkaline pH, while it is protonated at pH 7.5, is stabilized by a strong hydrogen bonding interaction, and weakly interacts with Fe(II). These data provide a benchmark for further analysis of c-type cytochromes with natural His/Cys coordination.
Collapse
Affiliation(s)
- Lidia Zuccarello
- CEA, CNRS, Aix Marseille Univ., BIAM, Interactions Protéine Métal UMR 7265, 13108 Saint Paul-Lez-Durance, France
- Aix Marseille Univ., CEA, CNRS, BIAM, Luminy Genetics and Biophysic of Plants, UMR 7265, 13288 Marseille Cedex, France
| | - Catherine Berthomieu
- CEA, CNRS, Aix Marseille Univ., BIAM, Interactions Protéine Métal UMR 7265, 13108 Saint Paul-Lez-Durance, France
| | - Alain Boussac
- I2BC, UMR CNRS 9198, CEA Saclay, 91191 Gif-sur-Yvette, France
| | - Jean-Blaise Brubach
- Synchrotron SOLEIL, AILES Beamline, L'Orme des Merisier, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France
| | - Irene Díaz-Moreno
- Instituto de Investigaciones Químicas (IIQ), Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla - Consejo Superior de Investigaciones Científicas (CSIC), Avda. Américo Vespucio 49, Sevilla 41092, Spain
| | - Antonio J Díaz Quintana
- Instituto de Investigaciones Químicas (IIQ), Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla - Consejo Superior de Investigaciones Científicas (CSIC), Avda. Américo Vespucio 49, Sevilla 41092, Spain
| | - Rainer Hienerwadel
- Aix Marseille Univ., CEA, CNRS, BIAM, Luminy Genetics and Biophysic of Plants, UMR 7265, 13288 Marseille Cedex, France
| |
Collapse
|
5
|
A detailed analysis of the spin-crossover reaction of H 2S binding to heme and the six-coordinated FeP(Im)-HS - porphyrin complex. J Inorg Biochem 2020; 206:111049. [PMID: 32171934 DOI: 10.1016/j.jinorgbio.2020.111049] [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: 10/28/2019] [Revised: 02/21/2020] [Accepted: 02/22/2020] [Indexed: 11/23/2022]
Abstract
The potential energy surfaces of the H2S binding to iron-porphyrin (FeP) with the imidazole (Im) ligand via intersystem crossings are investigated by using density functional theory. The minimum energy intersystem crossing point (MEISCP) between the quintet and triplet states (MEISCPTQ) for the Fe(II)P(Im)-H2S complex is located at a Fe-S distance of 3.39 Å with only 1.1 kcal/mol above the quintet state minimum. The second spin-crossover point, where a change from the triplet to the singlet state occurs, comes at a much shorter Fe-S distance of 2.79 Å, and the MEISCPST is located at 3.7 kcal/mol above the triplet state minimum. The nature of the chemical bonding along the Fe-S reaction coordinate from the ground state singlet to the quintet state along the path to the separated species is analyzed. An inspection of the vibrational modes reveals that the largest contribution to the triplet-quintet transition around the quintet and triplet state minimum comes from the symmetric shrinking of the pyrrole units of the porphyrin ring, indicating that the related reaction coordinate plays a main role in the intersystem crossing. The fully optimized structures of the Fe(II)P(Im)-HS- complex corresponding to three different spin multiplicities (M = 1, 3, 5) are characterized by a bent Fe-H-S conformation. The binding of the hydrosulfide anion to Fe(II)P(Im) in the quintet state induces a 0.2 Å displacement of the Fe atom out of the nitrogen porphyrin (Npyr) plane. The fully optimized structure of the ground state of Fe(II)P(Im)-HS- agrees well with experimental data for the corresponding heme models.
Collapse
|
6
|
Filipovic MR, Zivanovic J, Alvarez B, Banerjee R. Chemical Biology of H 2S Signaling through Persulfidation. Chem Rev 2018; 118:1253-1337. [PMID: 29112440 PMCID: PMC6029264 DOI: 10.1021/acs.chemrev.7b00205] [Citation(s) in RCA: 592] [Impact Index Per Article: 98.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Signaling by H2S is proposed to occur via persulfidation, a posttranslational modification of cysteine residues (RSH) to persulfides (RSSH). Persulfidation provides a framework for understanding the physiological and pharmacological effects of H2S. Due to the inherent instability of persulfides, their chemistry is understudied. In this review, we discuss the biologically relevant chemistry of H2S and the enzymatic routes for its production and oxidation. We cover the chemical biology of persulfides and the chemical probes for detecting them. We conclude by discussing the roles ascribed to protein persulfidation in cell signaling pathways.
Collapse
Affiliation(s)
- Milos R. Filipovic
- Univeristy of Bordeaux, IBGC, UMR 5095, F-33077 Bordeaux, France
- CNRS, IBGC, UMR 5095, F-33077 Bordeaux, France
| | - Jasmina Zivanovic
- Univeristy of Bordeaux, IBGC, UMR 5095, F-33077 Bordeaux, France
- CNRS, IBGC, UMR 5095, F-33077 Bordeaux, France
| | - Beatriz Alvarez
- Laboratorio de Enzimología, Facultad de Ciencias and Center for Free Radical and Biomedical Research, Universidad de la Republica, 11400 Montevideo, Uruguay
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0600, United States
| |
Collapse
|
7
|
Majtan T, Pey AL, Gimenez-Mascarell P, Martínez-Cruz LA, Szabo C, Kožich V, Kraus JP. Potential Pharmacological Chaperones for Cystathionine Beta-Synthase-Deficient Homocystinuria. Handb Exp Pharmacol 2018; 245:345-383. [PMID: 29119254 DOI: 10.1007/164_2017_72] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Classical homocystinuria (HCU) is the most common loss-of-function inborn error of sulfur amino acid metabolism. HCU is caused by a deficiency in enzymatic degradation of homocysteine, a toxic intermediate of methionine transformation to cysteine, chiefly due to missense mutations in the cystathionine beta-synthase (CBS) gene. As with many other inherited disorders, the pathogenic mutations do not target key catalytic residues, but rather introduce structural perturbations leading to an enhanced tendency of the mutant CBS to misfold and either to form nonfunctional aggregates or to undergo proteasome-dependent degradation. Correction of CBS misfolding would represent an alternative therapeutic approach for HCU. In this review, we summarize the complex nature of CBS, its multi-domain architecture, the interplay between the three cofactors required for CBS function [heme, pyridoxal-5'-phosphate (PLP), and S-adenosylmethionine (SAM)], as well as the intricate allosteric regulatory mechanism only recently understood, thanks to advances in CBS crystallography. While roughly half of the patients respond to treatment with a PLP precursor pyridoxine, many studies suggested usefulness of small chemicals, such as chemical and pharmacological chaperones or proteasome inhibitors, rescuing mutant CBS activity in cellular and animal models of HCU. Non-specific chemical chaperones and proteasome inhibitors assist in mutant CBS folding process and/or prevent its rapid degradation, thus resulting in increased steady-state levels of the enzyme and CBS activity. Recent interest in the field and available structural information will hopefully yield CBS-specific compounds, by using high-throughput screening and computational modeling of novel ligands, improving folding, stability, and activity of CBS mutants.
Collapse
Affiliation(s)
- Tomas Majtan
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, CO, USA.
| | - Angel L Pey
- Department of Physical Chemistry, University of Granada, Granada, Spain
| | - Paula Gimenez-Mascarell
- Structural Biology Unit, Center for Cooperative Research in Biosciences (CIC bioGUNE), Technology Park of Bizkaia, Derio, Spain
| | - Luis Alfonso Martínez-Cruz
- Structural Biology Unit, Center for Cooperative Research in Biosciences (CIC bioGUNE), Technology Park of Bizkaia, Derio, Spain
| | - Csaba Szabo
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX, USA
| | - Viktor Kožich
- Department of Pediatrics and Adolescent Medicine, Charles University-First Faculty of Medicine and General University Hospital in Prague, Prague 2, Czech Republic
| | - Jan P Kraus
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, CO, USA
| |
Collapse
|
8
|
Watanabe Y, Ishimori K, Uchida T. Dual role of the active-center cysteine in human peroxiredoxin 1: Peroxidase activity and heme binding. Biochem Biophys Res Commun 2017; 483:930-935. [DOI: 10.1016/j.bbrc.2017.01.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 01/09/2017] [Indexed: 01/07/2023]
|
9
|
Bostelaar T, Vitvitsky V, Kumutima J, Lewis BE, Yadav PK, Brunold TC, Filipovic M, Lehnert N, Stemmler TL, Banerjee R. Hydrogen Sulfide Oxidation by Myoglobin. J Am Chem Soc 2016; 138:8476-88. [PMID: 27310035 PMCID: PMC5464954 DOI: 10.1021/jacs.6b03456] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Enzymes in the sulfur network generate the signaling molecule, hydrogen sulfide (H2S), from the amino acids cysteine and homocysteine. Since it is toxic at elevated concentrations, cells are equipped to clear H2S. A canonical sulfide oxidation pathway operates in mitochondria, converting H2S to thiosulfate and sulfate. We have recently discovered the ability of ferric hemoglobin to oxidize sulfide to thiosulfate and iron-bound hydropolysulfides. In this study, we report that myoglobin exhibits a similar capacity for sulfide oxidation. We have trapped and characterized iron-bound sulfur intermediates using cryo-mass spectrometry and X-ray absorption spectroscopy. Further support for the postulated intermediates in the chemically challenging conversion of H2S to thiosulfate and iron-bound catenated sulfur products is provided by EPR and resonance Raman spectroscopy in addition to density functional theory computational results. We speculate that the unusual sensitivity of skeletal muscle cytochrome c oxidase to sulfide poisoning in ethylmalonic encephalopathy, resulting from the deficiency in a mitochondrial sulfide oxidation enzyme, might be due to the concentration of H2S by myoglobin in this tissue.
Collapse
Affiliation(s)
- Trever Bostelaar
- Department of Biological Chemistry, University of Michigan,
Ann Arbor, Michigan 48109, United States
| | - Victor Vitvitsky
- Department of Biological Chemistry, University of Michigan,
Ann Arbor, Michigan 48109, United States
| | - Jacques Kumutima
- Department of Chemistry and Department of Biophysics,
University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Brianne E. Lewis
- Department of Pharmaceutical Science, Wayne State
University, Detroit, Michigan 48201-2417, United States
| | - Pramod K. Yadav
- Department of Biological Chemistry, University of Michigan,
Ann Arbor, Michigan 48109, United States
| | - Thomas C. Brunold
- Department of Chemistry, University of Wisconsin, Madison,
Wisconsin 53706, United States
| | - Milos Filipovic
- University of Bordeaux, IBGC, and CNRS, IBGC, UMR 5095,
F-33077 Bordeaux, France
| | - Nicolai Lehnert
- Department of Chemistry and Department of Biophysics,
University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Timothy L. Stemmler
- Department of Pharmaceutical Science, Wayne State
University, Detroit, Michigan 48201-2417, United States
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan,
Ann Arbor, Michigan 48109, United States
| |
Collapse
|
10
|
Bagai I, Sarangi R, Fleischhacker A, Sharma A, Hoffman BM, Zuiderweg ERP, Ragsdale SW. Spectroscopic studies reveal that the heme regulatory motifs of heme oxygenase-2 are dynamically disordered and exhibit redox-dependent interaction with heme. Biochemistry 2015; 54:2693-708. [PMID: 25849895 PMCID: PMC4423204 DOI: 10.1021/bi501489r] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 03/09/2015] [Indexed: 11/28/2022]
Abstract
Heme oxygenase (HO) catalyzes a key step in heme homeostasis: the O2- and NADPH-cytochrome P450 reductase-dependent conversion of heme to biliverdin, Fe, and CO through a process in which the heme participates both as a prosthetic group and as a substrate. Mammals contain two isoforms of this enzyme, HO2 and HO1, which share the same α-helical fold forming the catalytic core and heme binding site, as well as a membrane spanning helix at their C-termini. However, unlike HO1, HO2 has an additional 30-residue N-terminus as well as two cysteine-proline sequences near the C-terminus that reside in heme regulatory motifs (HRMs). While the role of the additional N-terminal residues of HO2 is not yet understood, the HRMs have been proposed to reversibly form a thiol/disulfide redox switch that modulates the affinity of HO2 for ferric heme as a function of cellular redox poise. To further define the roles of the N- and C-terminal regions unique to HO2, we used multiple spectroscopic techniques to characterize these regions of the human HO2. Nuclear magnetic resonance spectroscopic experiments with HO2 demonstrate that, when the HRMs are in the oxidized state (HO2(O)), both the extra N-terminal and the C-terminal HRM-containing regions are disordered. However, protein NMR experiments illustrate that, under reducing conditions, the C-terminal region gains some structure as the Cys residues in the HRMs undergo reduction (HO2(R)) and, in experiments employing a diamagnetic protoporphyrin, suggest a redox-dependent interaction between the core and the HRM domains. Further, electron nuclear double resonance and X-ray absorption spectroscopic studies demonstrate that, upon reduction of the HRMs to the sulfhydryl form, a cysteine residue from the HRM region ligates to a ferric heme. Taken together with EPR measurements, which show the appearance of a new low-spin heme signal in reduced HO2, it appears that a cysteine residue(s) in the HRMs directly interacts with a second bound heme.
Collapse
Affiliation(s)
- Ireena Bagai
- Department
of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48019, United States
| | - Ritimukta Sarangi
- Stanford
Synchrotron
Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Angela
S. Fleischhacker
- Department
of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48019, United States
| | - Ajay Sharma
- Department
of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Brian M. Hoffman
- Department
of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Erik R. P. Zuiderweg
- Department
of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48019, United States
| | - Stephen W. Ragsdale
- Department
of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48019, United States
| |
Collapse
|
11
|
Smith AT, Pazicni S, Marvin KA, Stevens DJ, Paulsen KM, Burstyn JN. Functional divergence of heme-thiolate proteins: a classification based on spectroscopic attributes. Chem Rev 2015; 115:2532-58. [PMID: 25763468 DOI: 10.1021/cr500056m] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Aaron T Smith
- †Department of Molecular Biosciences, Northwestern University, 2205 Tech Drive, Evanston, Illinois 60208, United States
| | - Samuel Pazicni
- ‡Department of Chemistry, University of New Hampshire, 23 Academic Way, Durham, New Hampshire 03824, United States
| | - Katherine A Marvin
- §Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
| | - Daniel J Stevens
- ∥Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Katherine M Paulsen
- ∥Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Judith N Burstyn
- ∥Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| |
Collapse
|
12
|
Saha R, Bose M, Sen Santara S, Roy J, Adak S. Identification of proximal and distal axial ligands in Leishmania major pseudoperoxidase. Biochemistry 2013; 52:8878-87. [PMID: 24261670 DOI: 10.1021/bi401343t] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Previous optical and electron paramagnetic resonance (EPR) spectroscopic studies of the newly discovered peroxynitrite scavenging pseudoperoxidase from Leishmania major (LmPP) suggested that ferric LmPP contained a six-coordinate low-spin (6cLS) heme with a thiolate ligand, presumably a cysteine, bound to its heme iron. To identify the axial ligands of LmPP, we exploit a systematic mutational analysis of potential heme ligands. On the basis of UV-visible and EPR spectroscopy, we report that the substitution of the proximal His206 with alanine in LmPP alters the 6cLS to a five-coordinate high spin (5cHS) form at pH 4.0 that has a spectrum characteristic of a Cys-ligated 5cHS derivative. The electronic absorption and EPR analysis of all alanine-substituted Cys and Met single mutants establish that when Cys107 is replaced with alanine, a new species appears that has a spectrum characteristic of a histidine-ligated 5cHS derivative at pH 4.0. Together, these results suggest that His206 and Cys107 act as the proximal and distal axial ligands in ferric LmPP, respectively. However, the electronic properties of reduced wild-type LmPP are similar to those of known 5cHS His-ligated heme proteins at pH 8.8, indicating that the thiolate bond was broken upon reduction. Furthermore, the wild-type protein was only partially reduced at pH 4.0, but the E105L mutant was completely reduced to form a 5cHS ferrous heme. These results imply that the presence of an acidic residue near the distal site may prevent reduction of the heme iron at acidic pH.
Collapse
Affiliation(s)
- Rina Saha
- Division of Structural Biology and Bio-informatics, CSIR-Indian Institute of Chemical Biology , 4, Raja S. C. Mullick Road, Kolkata 700 032, India
| | | | | | | | | |
Collapse
|
13
|
Smith AT, Marvin KA, Freeman KM, Kerby RL, Roberts GP, Burstyn JN. Identification of Cys94 as the distal ligand to the Fe(III) heme in the transcriptional regulator RcoM-2 from Burkholderia xenovorans. J Biol Inorg Chem 2012; 17:1071-82. [PMID: 22855237 PMCID: PMC3484680 DOI: 10.1007/s00775-012-0920-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 07/03/2012] [Indexed: 10/28/2022]
Abstract
The CO-responsive transcriptional regulator RcoM from Burkholderia xenovorans (BxRcoM) was recently identified as a Cys(thiolate)-ligated heme protein that undergoes a redox-mediated ligand switch; however, the Cys bound to the Fe(III) heme was not identified. To that end, we generated and purified three Cys-to-Ser variants of BxRcoM-2--C94S, C127S, and C130S--and examined their spectroscopic properties in order to identify the native Cys(thiolate) ligand. Electronic absorption, resonance Raman, and electron paramagnetic resonance (EPR) spectroscopies demonstrate that the C127S and C130S variants, like wild-type BxRcoM-2, bind a six-coordinate low-spin Fe(III) heme using a Cys/His ligation motif. In contrast, electronic absorption and resonance Raman spectra of the C94S variant are most consistent with a mixture of five-coordinate high-spin and six-coordinate low-spin Fe(III) heme, neither of which are ligated by a Cys(thiolate) ligand. The EPR spectrum of C94S is dominated by a large, axial high-spin Fe(III) signal, confirming that the native ligation motif is not maintained in this variant. Together, these data reveal that Cys(94) is the distal Fe(III) heme ligand in BxRcoM-2; by sequence alignment, Cys(94) is also implicated as the distal Fe(III) heme ligand in BxRcoM-1, another homologue found in the same organism.
Collapse
Affiliation(s)
- Aaron T. Smith
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706, USA
| | - Katherine A. Marvin
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706, USA
| | - Katherine M. Freeman
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706, USA
| | - Robert L. Kerby
- Department of Bacteriology, University of Wisconsin–Madison, 1550 Linden Drive, Madison, WI 53706, USA
| | - Gary P. Roberts
- Department of Bacteriology, University of Wisconsin–Madison, 1550 Linden Drive, Madison, WI 53706, USA
| | - Judith N. Burstyn
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706, USA
| |
Collapse
|
14
|
Yadav PK, Xie P, Banerjee R. Allosteric communication between the pyridoxal 5'-phosphate (PLP) and heme sites in the H2S generator human cystathionine β-synthase. J Biol Chem 2012; 287:37611-20. [PMID: 22977242 DOI: 10.1074/jbc.m112.414706] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human cystathionine β-synthase (CBS) is a unique pyridoxal 5'-phosphate (PLP)-dependent enzyme that has a regulatory heme cofactor. Previous studies have demonstrated the importance of Arg-266, a residue at the heme pocket end of α-helix 8, for communication between the heme and PLP sites. In this study, we have examined the role of the conserved Thr-257 and Thr-260 residues, located at the other end of α-helix 8 on the heme electronic environment and on activity. The mutations at the two positions destabilize PLP binding, leading to lower PLP content and ~2- to ~500-fold lower activity compared with the wild-type enzyme. Activity is unresponsive to PLP supplementation, consistent with the pyridoxine-nonresponsive phenotype of the T257M mutation in a homocystinuric patient. The H(2)S-producing activities, also impacted by the mutations, show a different pattern of inhibition compared with the canonical transsulfuration reaction. Interestingly, the mutants exhibit contrasting sensitivities to the allosteric effector, S-adenosylmethionine (AdoMet); whereas T257M and T257I are inhibited, the other mutants are hyperactivated by AdoMet. All mutants showed an increased propensity of the ferrous heme to form an inactive species with a 424 nm Soret peak and exhibited significantly reduced enzyme activity in the ferrous and ferrous-CO states. Our results provide the first evidence for bidirectional transmission of information between the cofactor binding sites, suggest the additional involvement of this region in allosteric communication with the regulatory AdoMet-binding domain, and reveal the potential for independent modulation of the canonical transsulfuration versus H(2)S-generating reactions catalyzed by CBS.
Collapse
Affiliation(s)
- Pramod Kumar Yadav
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, USA
| | | | | |
Collapse
|
15
|
Smith AT, Su Y, Stevens DJ, Majtan T, Kraus JP, Burstyn JN. Effect of the disease-causing R266K mutation on the heme and PLP environments of human cystathionine β-synthase. Biochemistry 2012; 51:6360-70. [PMID: 22738154 DOI: 10.1021/bi300421z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cystathionine β-synthase (CBS) is an essential pyridoxal 5'-phosphate (PLP)-dependent enzyme of the transsulfuration pathway that condenses serine with homocysteine to form cystathionine; intriguingly, human CBS also contains a heme b cofactor of unknown function. Herein we describe the enzymatic and spectroscopic properties of a disease-associated R266K hCBS variant, which has an altered hydrogen-bonding environment. The R266K hCBS contains a low-spin, six-coordinate Fe(III) heme bearing a His/Cys ligation motif, like that of WT hCBS; however, there is a geometric distortion that exists at the R266K heme. Using rR spectroscopy, we show that the Fe(III)-Cys(thiolate) bond is longer and weaker in R266K, as evidenced by an 8 cm(-1) downshift in the ν(Fe-S) resonance. Presence of this longer and weaker Fe(III)-Cys(thiolate) bond is correlated with alteration of the fluorescence spectrum of the active PLP ketoenamine tautomer. Activity data demonstrate that, relative to WT, the R266K variant is more impaired in the alternative cysteine-synthesis reaction than in the canonical cystathionine-synthesis reaction. This diminished cysteine synthesis activity and a greater sensitivity to exogenous PLP correlate with the change in PLP environment. Fe-S(Cys) bond weakening causes a nearly 300-fold increase in the rate of ligand switching upon reduction of the R266K heme. Combined, these data demonstrate cross talk between the heme and PLP active sites, consistent with previous proposals, revealing that alteration of the Arg(266)-Cys(52) interaction affects PLP-dependent activity and dramatically destabilizes the ferrous thiolate-ligated heme complex, underscoring the importance of this hydrogen-bonding residue pair.
Collapse
Affiliation(s)
- Aaron T Smith
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
| | | | | | | | | | | |
Collapse
|
16
|
Perera R, Dawson JH. Modeling heme protein active sites with the his93gly cavity mutant of sperm whale myoglobin: complexes with nitrogen-, oxygen- and sulfur-donor proximal ligands. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424604000234] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Recent investigations of the His93Gly (H93G) "cavity" mutant of myoglobin as a versatile scaffold for modeling heme states are described. The difference in accessibility of the two sides of the heme in H93G myoglobin makes it possible to generate mixed ligand adducts in the ferric state that are difficult to prepare with heme models in organic solvents. In addition, the protection provided to the heme by the protein environment allows for the preparation of stable oxyferrous and oxo-iron(IV) complexes at near-ambient temperatures with variable ligands trans to the normally reactive dioxygen and oxo substituents. The extensive range of possible complexes that can be generated using the H93G system is illustrated with examples involving imidazole, phenolate, benzoate, thiolate and thiol ligands bound to the proximal side of the heme iron.
Collapse
Affiliation(s)
- Roshan Perera
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA
| | - John H. Dawson
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA
- School of Medicine, University of South Carolina, Columbia, SC 29208, USA
| |
Collapse
|
17
|
Kabil O, Weeks CL, Carballal S, Gherasim C, Alvarez B, Spiro TG, Banerjee R. Reversible heme-dependent regulation of human cystathionine β-synthase by a flavoprotein oxidoreductase. Biochemistry 2011; 50:8261-3. [PMID: 21875066 DOI: 10.1021/bi201270q] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human CBS is a PLP-dependent enzyme that clears homocysteine, gates the flow of sulfur into glutathione, and contributes to the biogenesis of H(2)S. The presence of a heme cofactor in CBS is enigmatic, and its conversion from the ferric- to ferrous-CO state inhibits enzyme activity. The low heme redox potential (-350 mV) has raised questions about the feasibility of the ferrous-CO state forming under physiological conditions. Herein, we provide the first evidence of reversible inhibition of CBS by CO in the presence of a human flavoprotein and NADPH. These data provide a mechanism for cross talk between two gas-signaling systems, CO and H(2)S, via heme-mediated allosteric regulation of CBS.
Collapse
Affiliation(s)
- Omer Kabil
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
| | | | | | | | | | | | | |
Collapse
|
18
|
Gardner JD, Pierce BS, Fox BG, Brunold TC. Spectroscopic and computational characterization of substrate-bound mouse cysteine dioxygenase: nature of the ferrous and ferric cysteine adducts and mechanistic implications. Biochemistry 2010; 49:6033-41. [PMID: 20397631 DOI: 10.1021/bi100189h] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cysteine dioxygenase (CDO) is a mononuclear non-heme Fe-dependent dioxygenase that catalyzes the initial step of oxidative cysteine catabolism. Its active site consists of an Fe(II) ion ligated by three histidine residues from the protein, an interesting variation on the more common 2-His-1-carboxylate motif found in many other non-heme Fe(II)-dependent enzymes. Multiple structural and kinetic studies of CDO have been carried out recently, resulting in a variety of proposed catalytic mechanisms; however, many open questions remain regarding the structure/function relationships of this vital enzyme. In this study, resting and substrate-bound forms of CDO in the Fe(II) and Fe(III) states, both of which are proposed to have important roles in this enzyme's catalytic mechanism, were characterized by utilizing various spectroscopic methods. The nature of the substrate/active site interactions was also explored using the cysteine analogue selenocysteine (Sec). Our electronic absorption, magnetic circular dichroism, and resonance Raman data exhibit features characteristic of direct S (or Se) ligation to both the high-spin Fe(II) and Fe(III) active site ions. The resulting Cys- (or Sec-) bound species were modeled and further characterized using density functional theory computations to generate experimentally validated geometric and electronic structure descriptions. Collectively, our results yield a more complete description of several catalytically relevant species and provide support for a reaction mechanism similar to that established for many structurally related 2-His-1-carboxylate Fe(II)-dependent dioxygenases.
Collapse
Affiliation(s)
- Jessica D Gardner
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | | | | | | |
Collapse
|
19
|
Karunakaran V, Benabbas A, Sun Y, Zhang Z, Singh S, Banerjee R, Champion PM. Investigations of low-frequency vibrational dynamics and ligand binding kinetics of cystathionine beta-synthase. J Phys Chem B 2010; 114:3294-306. [PMID: 20155941 DOI: 10.1021/jp909700r] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Vibrational coherence spectroscopy is used to study the low frequency dynamics of the truncated dimer of human cystathionine beta-synthase (CBS). CBS is a pyridoxal-5'-phosphate-dependent heme enzyme with cysteine and histidine axial ligands that catalyzes the condensation of serine and homocysteine to form cystathionine. A strong correlation between the "detuned" coherence spectrum (which probes higher frequencies) and the Raman spectrum is demonstrated, and a rich pattern of modes below 200 cm(-1) is revealed. Normal coordinate structural decomposition (NSD) of the ferric CBS crystal structure predicts the enhancement of normal modes with significant heme "doming", "ruffling", and "saddling" content, and they are observed in the coherence spectra near approximately 40, approximately 60, and approximately 90 cm(-1). When pH is varied, the relative intensities and frequencies of the low frequency heme modes indicate the presence of a unique protein-induced heme structural perturbation near pH 7 that differs from what is observed at higher or lower pH. For ferric CBS, we observe a new mode near approximately 25 cm(-1), possibly involving the response of the protein, which exhibits a phase jump of approximately pi for excitation on the blue and red side of the Soret band maximum. The low frequency vibrational coherence spectrum of ferrous CBS is also presented, along with our efforts to probe its NO-bound complex. The CO geminate rebinding kinetics of CBS are similar to the CO-bound form of the gene activator protein CooA, but with the appearance of a significant additional kinetic inhomogeneity. Analysis of this inhomogeneity suggests that it arises from the two subunits of CBS and leads to a factor of approximately 20 for the ratio of the average CO geminate rebinding rates of the two subunits.
Collapse
Affiliation(s)
- Venugopal Karunakaran
- Department of Physics and Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, Massachusetts 02115, USA
| | | | | | | | | | | | | |
Collapse
|
20
|
Weeks CL, Singh S, Madzelan P, Banerjee R, Spiro TG. Heme regulation of human cystathionine beta-synthase activity: insights from fluorescence and Raman spectroscopy. J Am Chem Soc 2009; 131:12809-16. [PMID: 19722721 DOI: 10.1021/ja904468w] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cystathionine beta-synthase (CBS) plays a central role in homocysteine metabolism, and malfunction of the enzyme leads to homocystinuria, a devastating metabolic disease. CBS contains a pyridoxal 5'-phosphate (PLP) cofactor which catalyzes the synthesis of cystathionine from homocysteine and serine. Mammalian forms of the enzyme also contain a heme group, which is not involved in catalysis. It may, however, play a regulatory role, since the enzyme is inhibited when CO or NO are bound to the heme. We have investigated the mechanism of this inhibition using fluorescence and resonance Raman spectroscopies. CO binding is found to induce a tautomeric shift of the PLP from the ketoenamine to the enolimine form. The ketoenamine is key to PLP reactivity because its imine C horizontal lineN bond is protonated, facilitating attack by the nucleophilic substrate, serine. The same tautomer shift is also induced by heat inactivation of Fe(II)CBS, or by an Arg266Met replacement in Fe(II)CBS, which likewise inactivates the enzyme; in both cases the endogenous Cys52 ligand to the heme is replaced by another, unidentified ligand. CO binding also displaces Cys52 from the heme. We propose that the tautomer shift results from loss of a stabilizing H-bond from Asn149 to the PLP ring O3' atom, which is negatively charged in the ketoenamine tautomer. This loss would be induced by displacement of the PLP as a result of breaking the salt bridge between Cys52 and Arg266, which resides on a short helix that is also anchored to the PLP via H-bonds to its phosphate group. The salt bridge would be broken when Cys52 is displaced from the heme. Cys52 protonation is inferred to be the rate-limiting step in breaking the salt bridge, since the rate of the tautomer shift, following CO binding, increases with decreasing pH. In addition, elevation of the concentration of phosphate buffer was found to diminish the rate and extent of the tautomer shift, suggesting a ketoenamine-stabilizing phosphate binding site, possibly at the protonated imine bond of the PLP. Implications of these findings for CBS regulation are discussed.
Collapse
Affiliation(s)
- Colin L Weeks
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | | | | | | | | |
Collapse
|
21
|
Marvin KA, Reinking JL, Lee AJ, Pardee K, Krause HM, Burstyn JN. Nuclear receptors homo sapiens Rev-erbbeta and Drosophila melanogaster E75 are thiolate-ligated heme proteins which undergo redox-mediated ligand switching and bind CO and NO. Biochemistry 2009; 48:7056-71. [PMID: 19405475 DOI: 10.1021/bi900697c] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Nuclear receptors E75, which regulates development in Drosophila melanogaster, and Rev-erbbeta, which regulates circadian rhythm in humans, bind heme within their ligand binding domains (LBD). The heme-bound ligand binding domains of E75 and Rev-erbbeta were studied using electronic absorption, MCD, resonance Raman, and EPR spectroscopies. Both proteins undergo redox-dependent ligand switching and CO- and NO-induced ligand displacement. In the Fe(III) oxidation state, the nuclear receptor hemes are low spin and 6-coordinate with cysteine(thiolate) as one of the two axial heme ligands. The sixth ligand is a neutral donor, presumably histidine. When the heme is reduced to the Fe(II) oxidation state, the cysteine(thiolate) is replaced by a different neutral donor ligand, whose identity is not known. CO binds to the Fe(II) heme in both E75(LBD) and Rev-erbbeta(LBD) opposite a sixth neutral ligand, plausibly the same histidine that served as the sixth ligand in the Fe(III) state. NO binds to the heme of both proteins; however, the NO-heme is 5-coordinate in E75 and 6-coordinate in Rev-erbbeta. These nuclear receptors exhibit coordination characteristics that are similar to other known redox and gas sensors, suggesting that E75 and Rev-erbbeta may function in heme-, redox-, or gas-regulated control of cellular function.
Collapse
Affiliation(s)
- Katherine A Marvin
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA
| | | | | | | | | | | |
Collapse
|
22
|
Singh S, Madzelan P, Stasser J, Weeks CL, Becker D, Spiro TG, Penner-Hahn J, Banerjee R. Modulation of the heme electronic structure and cystathionine beta-synthase activity by second coordination sphere ligands: The role of heme ligand switching in redox regulation. J Inorg Biochem 2009; 103:689-97. [PMID: 19232736 DOI: 10.1016/j.jinorgbio.2009.01.009] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 01/05/2009] [Accepted: 01/07/2009] [Indexed: 11/30/2022]
Abstract
In humans, cystathionine beta-synthase (CBS) is a hemeprotein, which catalyzes a pyridoxal phosphate (PLP)-dependent condensation reaction. Changes in the heme environment are communicated to the active site, which is approximately 20A away. In this study, we have examined the role of H67 and R266, which are in the second coordination sphere of the heme ligands, H65 and C52, respectively, in modulating the heme's electronic properties and in transmitting information between the heme and active sites. While the H67A mutation is comparable to wild-type CBS, interesting differences are revealed by mutations at the R266 site. The pathogenic mutant, R266K, is moderately PLP-responsive while the R266M mutation shows dramatic differences in the ferrous state. The electrostatic interaction between C52 and R266 is critical for stabilizing the ferrous heme and its disruption leads to the facile formation of a 424nm (C-424) absorbing ferrous species, which is inactive, compared to the active 449nm ferrous species for wild-type CBS. Resonance Raman studies on the R266M mutant reveal that the kinetics of C52 rebinding after Fe-CO photolysis are comparable to that of wild-type CBS. EXAFS studies on C-424 CBS are consistent with the presence of two axial N/O low Z scatters with only one being a rigid unit of a histidine residue while the other could be a solvent molecule, an oxygen atom from the peptide backbone or a side chain nitrogen. The redox potential for the heme in full-length CBS is -350+/-4mV and is substantially lower than the value of -287+/-2mV determined for truncated CBS. A redox-regulated ligand change has the potential to serve as an allosteric on/off switch in human CBS and the second sphere ligand, R266, plays an important role in this transition.
Collapse
Affiliation(s)
- Sangita Singh
- Department of Biological Chemistry, University of Michigan, Ann Arbor, 48109-0606, United States
| | | | | | | | | | | | | | | |
Collapse
|
23
|
Modulation of Cystathionine β-Synthase Activity by the Arg-51 and Arg-224 Mutations. Biosci Biotechnol Biochem 2008; 72:2318-23. [DOI: 10.1271/bbb.80231] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
24
|
Marvin KA, Kerby RL, Youn H, Roberts GP, Burstyn JN. The transcription regulator RcoM-2 from Burkholderia xenovorans is a cysteine-ligated hemoprotein that undergoes a redox-mediated ligand switch. Biochemistry 2008; 47:9016-28. [PMID: 18672900 DOI: 10.1021/bi800486x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Spectroscopic characterization of the newly discovered heme-PAS domain sensor protein BxRcoM-2 reveals that this protein undergoes redox-dependent ligand switching and CO- and NO-induced ligand displacement. The aerobic bacterium Burkholderia xenovorans expresses two homologous heme-containing proteins that promote CO-dependent transcription in vivo. These regulators of CO metabolism, BxRcoM-1 and BxRcoM-2, are gas-responsive heme-PAS domain proteins like mammalian neuronal PAS domain protein 2 (NPAS2) and the direct oxygen sensor from Escherichia coli ( EcDos). BxRcoM-2 was studied using electronic absorption, MCD, resonance Raman, and EPR spectroscopies. In the Fe(III) oxidation state, the heme is low-spin and six-coordinate with a cysteine(thiolate) as one of the two ligands. The sixth ligand is a histidine (His (74)), which is present in all states of the protein that were studied. Reduction to the Fe(II) oxidation state results in replacement of the cysteine(thiolate) with a neutral thioether ligand, Met (104). CO and NO bind to the Fe(II) BxRcoM-2 heme opposite the histidine ligand. Thus, BxRcoM-2 employs coordination state changes similar to those known for CO-sensing CooA, with redox-dependent loss of a cysteine(thiolate) ligand and displacement of a relatively weakly bound axial ligand by the effector gas molecule. Like EcDos, the weakly bound axial ligand that is displaced is methionine.
Collapse
Affiliation(s)
- Katherine A Marvin
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | | | | | | | | |
Collapse
|
25
|
Singh S, Madzelan P, Banerjee R. Properties of an unusual heme cofactor in PLP-dependent cystathionine beta-synthase. Nat Prod Rep 2007; 24:631-9. [PMID: 17534535 DOI: 10.1039/b604182p] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Sangita Singh
- Redox Biology Center and Department of Biochemistry, University of Nebraska, Lincoln, NE 68588-0664, USA
| | | | | |
Collapse
|
26
|
Rong C, Lian S, Yin D, Zhong A, Zhang R, Liu S. Effective simulation of biological systems: Choice of density functional and basis set for heme-containing complexes. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2006.11.092] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
27
|
Banerjee R, Zou CG. Redox regulation and reaction mechanism of human cystathionine-beta-synthase: a PLP-dependent hemesensor protein. Arch Biochem Biophys 2005; 433:144-56. [PMID: 15581573 DOI: 10.1016/j.abb.2004.08.037] [Citation(s) in RCA: 167] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Revised: 08/16/2004] [Indexed: 10/26/2022]
Abstract
Cystathionine beta-synthase in mammals lies at a pivotal crossroad in methionine metabolism directing flux toward cysteine synthesis and catabolism. The enzyme exhibits a modular organization and complex regulation. It catalyzes the beta-replacement of the hydroxyl group of serine with the thiolate of homocysteine and is unique in being the only known pyridoxal phosphate-dependent enzyme that also contains heme b as a cofactor. The heme functions as a sensor and modulates enzyme activity in response to redox change and to CO binding. Mutations in this enzyme are the single most common cause of hereditary hyperhomocysteinemia. Elucidation of the crystal structure of a truncated and highly active form of the human enzyme containing the heme- and pyridoxal phosphate binding domains has afforded a structural perspective on mechanistic and mutation analysis studies. The C-terminal regulatory domain containing two CBS motifs exerts intrasteric regulation and binds the allosteric activator, S-adenosylmethionine. Studies with mammalian cells in culture as well as with animal models have unraveled multiple layers of regulation of cystathionine beta-synthase in response to redox perturbations and reveal the important role of this enzyme in glutathione-dependent redox homestasis. This review discusses the recent advances in our understanding of the structure, mechanism, and regulation of cystathionine beta-synthase from the perspective of its physiological function, focusing on the clinically relevant human enzyme.
Collapse
Affiliation(s)
- Ruma Banerjee
- Department of Biochemistry, University of Nebraska, Lincoln, NE 68588-0664, USA.
| | | |
Collapse
|
28
|
Igarashi J, Sato A, Kitagawa T, Yoshimura T, Yamauchi S, Sagami I, Shimizu T. Activation of heme-regulated eukaryotic initiation factor 2alpha kinase by nitric oxide is induced by the formation of a five-coordinate NO-heme complex: optical absorption, electron spin resonance, and resonance raman spectral studies. J Biol Chem 2004; 279:15752-62. [PMID: 14752110 DOI: 10.1074/jbc.m310273200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Heme-regulated eukaryotic initiation factor 2alpha kinase (HRI) regulates the synthesis of hemoglobin in reticulocytes in response to heme availability. HRI contains a tightly bound heme at the N-terminal domain. Earlier reports show that nitric oxide (NO) regulates HRI catalysis. However, the mechanism of this process remains unclear. In the present study, we utilize in vitro kinase assays, optical absorption, electron spin resonance (ESR), and resonance Raman spectra of purified full-length HRI for the first time to elucidate the regulation mechanism of NO. HRI was activated via heme upon NO binding, and the Fe(II)-HRI(NO) complex displayed 5-fold greater eukaryotic initiation factor 2alpha kinase activity than the Fe(III)-HRI complex. The Fe(III)-HRI complex exhibited a Soret peak at 418 nm and a rhombic ESR signal with g values of 2.49, 2.28, and 1.87, suggesting coordination with Cys as an axial ligand. Interestingly, optical absorption, ESR, and resonance Raman spectra of the Fe(II)-NO complex were characteristic of five-coordinate NO-heme. Spectral findings on the coordination structure of full-length HRI were distinct from those obtained for the isolated N-terminal heme-binding domain. Specifically, six-coordinate NO-Fe(II)-His was observed but not Cys-Fe(III) coordination. It is suggested that significant conformational change(s) in the protein induced by NO binding to the heme lead to HRI activation. We discuss the role of NO and heme in catalysis by HRI, focusing on heme-based sensor proteins.
Collapse
Affiliation(s)
- Jotaro Igarashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | | | | | | | | | | | | |
Collapse
|
29
|
Banerjee R, Evande R, Kabil O, Ojha S, Taoka S. Reaction mechanism and regulation of cystathionine beta-synthase. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1647:30-5. [PMID: 12686104 DOI: 10.1016/s1570-9639(03)00044-x] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In mammals, cystathionine beta-synthase catalyzes the first step in the transsulfuration pathway which provides an avenue for the conversion of the essential amino acid, methionine, to cysteine. Cystathionine beta-synthase catalyzes a PLP-dependent condensation of serine and homocysteine to cystathionine and is unique in also having a heme cofactor. In this review, recent advances in our understanding of the kinetic mechanism of the yeast and human enzymes as well as pathogenic mutants of the human enzyme and insights into the role of heme in redox sensing are discussed from the perspective of the crystal structure of the catalytic core of the human enzyme.
Collapse
Affiliation(s)
- Ruma Banerjee
- Biochemistry Department, University of Nebraska, Lincoln, NE 68588-0664, USA.
| | | | | | | | | |
Collapse
|
30
|
Perera R, Sono M, Sigman JA, Pfister TD, Lu Y, Dawson JH. Neutral thiol as a proximal ligand to ferrous heme iron: implications for heme proteins that lose cysteine thiolate ligation on reduction. Proc Natl Acad Sci U S A 2003; 100:3641-6. [PMID: 12655049 PMCID: PMC152975 DOI: 10.1073/pnas.0737142100] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cysteine plays a key role as a metal ligand in metalloproteins. In all well-recognized cases, however, it is the anionic cysteinate that coordinates. Several cysteinate-ligated heme proteins are known, but some fail to retain thiolate ligation in the ferrous state, possibly following protonation to form neutral cysteine. Ligation by cysteine thiol in ferrous heme proteins has not been documented. To establish spectroscopic signatures for such systems, we have prepared five-coordinate adducts of the ferrous myoglobin H94G cavity mutant with neutral thiol and thioether sulfur donors as well as six-coordinate derivatives such as with CO and, when possible, with NO and O(2). A thiol-ligated oxyferrous complex is reported, to our knowledge for the first time. Further, a bis-thioether ferrous H93G model for bis-methionine ligation, as found in Pseudomonas aeruginosa bacterioferritin heme protein, is described. Magnetic CD spectroscopy has been used due to its established ability in axial ligand identification. The magnetic CD spectra of the H93G complexes have been compared with those of ferrous H175CD235L cytochrome c peroxidase to show that its proximal ligand is neutral cysteine. We had previously reported this cytochrome c peroxidase mutant to be cysteinate-ligated in the ferric state, but the ferrous ligand was undetermined. The spectral properties of ferrous liver microsomal cytochrome P420 (inactive P450) are also consistent with thiol ligation. This study establishes that neutral cysteine can serve as a ligand in ferrous heme iron proteins, and that ferric cysteinate-ligated heme proteins that fail to retain such ligation on reduction may simply be ligated by neutral cysteine.
Collapse
Affiliation(s)
- Roshan Perera
- Department of Chemistry and Biochemistry and School of Medicine, University of South Carolina, Columbia, SC 29208, USA
| | | | | | | | | | | |
Collapse
|
31
|
Clay MD, Jenney FE, Noh HJ, Hagedoorn PL, Adams MWW, Johnson MK. Resonance Raman characterization of the mononuclear iron active-site vibrations and putative electron transport pathways in Pyrococcus furiosus superoxide reductase. Biochemistry 2002; 41:9833-41. [PMID: 12146949 DOI: 10.1021/bi025833b] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The resonance Raman spectrum of oxidized wild-type P. furiosus SOR at pH 7.5 and 10.5 has been investigated using excitation wavelengths between 406 and 676 nm, and vibrational modes have been assigned on the basis of isotope shifts resulting from global replacements of (32)S with (34)S, (14)N with (15)N, (56)Fe with (54)Fe, and exchange into a H(2)(18)O buffer. The results are interpreted in terms of the crystallographically defined active-site structure involving a six-coordinate mononuclear Fe center with four equatorial histidine ligands and axial cysteine and monodentate glutamate ligands (Yeh, A. P., Hu, Y., Jenney, F. E., Adams, M. W. W., and Rees, D. C. (2000) Biochemistry 39, 2499-2508). Excitation into the intense (Cys)S(p(pi))-to-Fe(d(pi)) CT transition centered at 660 nm results in strong enhancement of modes at 298 cm(-1) and 323 cm(-1) that are assigned to extensively mixed cysteine S-C(beta)-C(alpha) bending and Fe-S(Cys) stretching modes, respectively. All other higher-energy vibrational modes are readily assigned to overtone or combination bands or to fundamentals corresponding to internal modes of the ligated cysteine. Weak enhancement of Fe-N(His) stretching modes is observed in the 200-250 cm(-1) region. The enhancement of internal cysteine modes and Fe-N(His) stretching modes are a consequence of a near-planar Fe-S-C(beta)-C(alpha)-N unit for the coordinated cysteine and significant (His)N(p(pi))-Fe(d(xy))-(Cys)S(p(pi)) orbital overlap, respectively, and have close parallels to type 1 copper proteins. By analogy with type 1 copper proteins, putative superexchange electron-transfer pathways to the mononuclear Fe active site are identified involving either the tyrosine and cysteine residues or the solvent-exposed deltaN histidine residue in a Y-C-X-X-H arrangement. Studies of wild-type at pH 10.5 and the E14A variant indicate that the resonance Raman spectrum is remarkably insensitive to changes in the ligand trans to cysteine and hence are inconclusive concerning the origin of the alkaline transition and the nature of sixth Fe ligand in the E14A variant.
Collapse
Affiliation(s)
- Michael D Clay
- Department of Chemistry, Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30602, USA
| | | | | | | | | | | |
Collapse
|
32
|
Taoka S, Green EL, Loehr TM, Banerjee R. Mercuric chloride-induced spin or ligation state changes in ferric or ferrous human cystathionine beta-synthase inhibit enzyme activity. J Inorg Biochem 2001; 87:253-9. [PMID: 11744063 DOI: 10.1016/s0162-0134(01)00336-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cystathionine beta-synthase is a key heme and pyridoxal phosphate-dependent enzyme involved in homocysteine metabolism in humans. The role of the recently discovered heme in this protein remains an important open question. The axial ligands to the heme in both the ferrous and ferric states have been assigned as cysteine and histidine residues, respectively. In this study, we have examined the effect of ligation and spin state changes in the heme on the activity of the enzyme. Treatment of the ferric enzyme with HgCl2 results in the conversion of six-coordinate low-spin heme to five-coordinate high-spin heme and is paralleled by a loss of activity. In contrast, treatment of the ferrous enzyme with HgCl2 results in replacement of the cysteine ligand by an unidentified sixth ligand and retention of the six-coordinate state, and is also accompanied by loss of enzyme activity. Treatment of the five-coordinate HgCl2-treated enzyme with thiols, such as homocysteine, results in reversion to a six-coordinate state. Resonance Raman spectroscopy with 34S-labeled enzyme reveals the return of the endogenous thiol ligand under these conditions and rules out direct coordination by the thiolate of homocysteine to the heme.
Collapse
Affiliation(s)
- S Taoka
- Department of Biochemistry, University of Nebraska, Lincoln, NE 68588-0664, USA
| | | | | | | |
Collapse
|
33
|
Taoka S, Banerjee R. Characterization of NO binding to human cystathionine beta-synthase: possible implications of the effects of CO and NO binding to the human enzyme. J Inorg Biochem 2001; 87:245-51. [PMID: 11744062 DOI: 10.1016/s0162-0134(01)00335-x] [Citation(s) in RCA: 155] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Homocysteine is a key junction metabolite that can be converted to cystathionine in a reaction catalyzed by the heme and pyridoxal phosphate-dependent cystathionine beta-synthase. The heme has unusual spectroscopic properties and the axial ligands have been assigned as histidine and cysteine, respectively. Its role in the protein is not obvious from the chemistry of the beta-replacement reaction that is catalyzed. We have characterized the binding of the gaseous signaling molecule, NO, to cystathionine beta-synthase and examined its effect on the reactions catalyzed by the truncated dimeric form of the enzyme, W409X, which is a natural variant. Binding of NO appears to result in the formation of a five-coordinate ferrous nitrosyl species in which both endogenous ligands have been lost. This is in contrast to CO binding which is reported to displace the thiolate ligand and form a six-coordinate species. NO binds to the full-length enzyme with a K(d) of 281+/-50 microM and to the truncated enzyme with a K(d) of 350+/-44 microM. Binding of NO to the full-length enzyme inhibits activity with a K(i) of 320+/-60 microM. These studies demonstrate that as with CO, perturbation of the heme environment by NO is communicated to the active site with concomitant inhibition of enzyme activity, and suggests a regulatory role for heme in cystathionine beta-synthase.
Collapse
Affiliation(s)
- S Taoka
- Department of Biochemistry, University of Nebraska, Lincoln, NE 68588-0664, USA
| | | |
Collapse
|
34
|
Kabil O, Toaka S, LoBrutto R, Shoemaker R, Banerjee R. Pyridoxal phosphate binding sites are similar in human heme-dependent and yeast heme-independent cystathionine beta-synthases. Evidence from 31P NMR and pulsed EPR spectroscopy that heme and PLP cofactors are not proximal in the human enzyme. J Biol Chem 2001; 276:19350-5. [PMID: 11278994 DOI: 10.1074/jbc.m100029200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two classes of cystathionine beta-synthases have been identified in eukaryotes, the heme-independent enzyme found in yeast and the heme-dependent form found in mammals. Both classes of enzymes catalyze a pyridoxal phosphate (PLP)-dependent condensation of serine and homocysteine to produce cystathionine. The role of the heme in the human enzyme and its location relative to the PLP in the active site are unknown. (31)P NMR spectroscopy revealed that spin-lattice relaxation rates of the phosphorus nucleus in PLP are similar in both the paramagnetic ferric (T(1) = 6.34 +/- 0.01 s) and the diamagnetic ferrous (T(1) = 5.04 +/- 0.06 s) enzyme, suggesting that the two cofactors are not proximal to each other. This is also supported by pulsed EPR studies that do not provide any evidence for strong or weak coupling between the phosphorus nucleus and the ferric iron. However, the (31)P signal in the reduced enzyme moved from 5.4 to 2.2 ppm, and the line width decreased from 73 to 16 Hz, providing the first structural evidence for transmission to the active site of an oxidation state change in the heme pocket. These results are consistent with a regulatory role for the heme as suggested by previous biochemical studies from our laboratory. The (31)P chemical shifts of the resting forms of the yeast and human enzymes are similar, suggesting that despite the difference in their heme content, the microenvironment of the PLP is similar in the two enzymes. The addition of the substrate, serine, resulted in an upfield shift of the phosphorus resonance in both enzymes, signaling formation of reaction intermediates. The resting enzyme spectra were recovered following addition of excess homocysteine, indicating that both enzymes retained catalytic activity during the course of the NMR experiment.
Collapse
Affiliation(s)
- O Kabil
- Department of Biochemistry, University of Nebraska, Lincoln, Nebraska 68588-0664, USA
| | | | | | | | | |
Collapse
|
35
|
Vadon-Le Goff S, Delaforge M, Boucher JL, Janosik M, Kraus JP, Mansuy D. Coordination chemistry of the heme in cystathionine beta-synthase: formation of iron(II)-isonitrile complexes. Biochem Biophys Res Commun 2001; 283:487-92. [PMID: 11327727 DOI: 10.1006/bbrc.2001.4807] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Interaction of rat and human cystathionine-beta-synthase (CBS) with various potential ligands has been studied by visible and EPR spectroscopy in order to explore the coordination chemistry of this atypical hemeprotein. Ferric CBS did not react with any classical hemeprotein ligands, such as various imidazole and pyridine derivatives, N(-)(3) and isonitriles RNC. Ferrous CBS also failed to bind these nitrogenous ligands or nitrosoalkanes. However, it reacts with various isonitriles RNC, leading to complexes characterized by a Soret peak at 433 +/- 2 nm. Binding of isonitriles to ferrous CBS is a relatively slow process; its rate markedly depends on the nature of R. It thus seems that the only exogenous ligands able to bind CBS iron are carbon-centered, very strong heme-Fe(II) ligands such as CNR, CO, and CN(-), presumably after dissociation of the CBS-iron(II)-cysteinate bond. Isonitriles appear as interesting tools for further studies on the topology of CBS active site.
Collapse
Affiliation(s)
- S Vadon-Le Goff
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR 8601 CNRS, Université Paris V, 45 Rue des Saints-Pères, Paris Cedex 06, 75270, France
| | | | | | | | | | | |
Collapse
|