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Al-Sadeq DW, Conter C, Thanassoulas A, Al-Dewik N, Safieh-Garabedian B, Martínez-Cruz LA, Nasrallah GK, Astegno A, Nomikos M. Biochemical and structural impact of two novel missense mutations in cystathionine β-synthase gene associated with homocystinuria. Biochem J 2024; 481:569-585. [PMID: 38563463 DOI: 10.1042/bcj20240012] [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: 01/16/2024] [Revised: 02/25/2024] [Accepted: 03/28/2024] [Indexed: 04/04/2024]
Abstract
Homocystinuria is a rare disease caused by mutations in the CBS gene that results in a deficiency of cystathionine β-synthase (CBS). CBS is an essential pyridoxal 5'-phosphate (PLP)-dependent enzyme in the transsulfuration pathway, responsible for combining serine with homocysteine to produce cystathionine, whose activity is enhanced by the allosteric regulator S-adenosylmethionine (SAM). CBS also plays a role in generating hydrogen sulfide (H2S), a gaseous signaling molecule with diverse regulatory functions within the vascular, nervous, and immune systems. In this study, we present the clinical and biochemical characterization of two novel CBS missense mutations that do not respond to pyridoxine treatment, namely c.689T > A (L230Q) and 215A > T (K72I), identified in a Chinese patient. We observed that the disease-associated K72I genetic variant had no apparent effects on the spectroscopic and catalytic properties of the full-length enzyme. In contrast, the L230Q variant expressed in Escherichia coli did not fully retain heme and when compared with the wild-type enzyme, it exhibited more significant impairments in both the canonical cystathionine-synthesis and the alternative H2S-producing reactions. This reduced activity is consistent with both in vitro and in silico evidence, which indicates that the L230Q mutation significantly decreases the overall protein's stability, which in turn, may represent the underlying cause of its pathogenicity.
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Affiliation(s)
- Duaa W Al-Sadeq
- College of Medicine, QU Health, Qatar University, Doha, Qatar
- Biomedical Research Center, Qatar University, Doha, Qatar
| | - Carolina Conter
- Department of Biotechnology, University of Verona, Verona, Italy
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Derio, Spain
| | | | - Nader Al-Dewik
- Department of Research and Translational and Precision Medicine Research Lab, Women's Wellness and Research Center, Hamad Medical Corporation, and Genomics and Precision Medicine (GPM), College of Health & Life Science (CHLS), Hamad Bin Khalifa University (HBKU), Doha, Qatar
| | | | - Luis Alfonso Martínez-Cruz
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Derio, Spain
| | - Gheyath K Nasrallah
- Biomedical Research Center, Qatar University, Doha, Qatar
- Department of Biomedical Sciences, College of Health Sciences, QU Health, Qatar University, Doha, Qatar
| | | | - Michail Nomikos
- College of Medicine, QU Health, Qatar University, Doha, Qatar
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2
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Al-Sadeq DW, Thanassoulas A, Theodoridou M, Nasrallah GK, Nomikos M. Pathogenic Homocystinuria-Associated T236N Mutation Dramatically Alters the Biochemical Properties of Cystathionine Beta-Synthase Protein. Biomedicines 2024; 12:929. [PMID: 38790892 PMCID: PMC11118236 DOI: 10.3390/biomedicines12050929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 04/03/2024] [Accepted: 04/09/2024] [Indexed: 05/26/2024] Open
Abstract
BACKGROUND Cystathione beta-synthase (CBS) T236N is a novel mutation associated with pyridoxine non-responsiveness, which presents a significant difficulty in the medical treatment of homocystinuria. Reported severe phenotypes in homocystinuria patients highlight the urgent requirement to comprehend the molecular mechanisms underlying mutation pathogenicity for the advancement of the disease. METHODOLOGY In this study, we used a multidisciplinary approach to investigate the molecular properties of bacterially expressed and purified recombinant CBST236N protein, which we directly compared to those of the wild-type (CBSWT) protein. RESULTS Our data revealed a profound impact of the p.T236N mutation on CBS enzymatic activity, with a dramatic reduction of ~96% compared to the CBSWT protein. Circular dichroism (CD) experiments indicated that the p.T236N mutation did not significantly alter the secondary structure of the protein. However, CD spectra unveiled distinct differences in the thermal stability of CBSWT and CBST236N mutant protein species. In addition, chemical denaturation experiments further highlighted that the CBSWT protein exhibited greater thermodynamic stability than the CBST236N mutant, suggesting a destabilizing effect of this mutation. CONCLUSIONS Our findings provide an explanation of the pathogenicity of the p.T236N mutation, shedding light on its role in severe homocystinuria phenotypes. This study contributes to a deeper understanding of CBS deficiency and may improve the development of targeted therapeutic strategies for affected individuals.
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Affiliation(s)
- Duaa W. Al-Sadeq
- Biomedical Research Center, Qatar University, Doha P.O. Box 2713, Qatar; (D.W.A.-S.); (G.K.N.)
- College of Medicine, QU Health, Qatar University, Doha P.O. Box 2713, Qatar;
| | | | - Maria Theodoridou
- Biomedical Research Center, Qatar University, Doha P.O. Box 2713, Qatar; (D.W.A.-S.); (G.K.N.)
| | - Gheyath K. Nasrallah
- Biomedical Research Center, Qatar University, Doha P.O. Box 2713, Qatar; (D.W.A.-S.); (G.K.N.)
- Department of Biomedical Science, College of Health Sciences, QU Health, Qatar University, Doha P.O. Box 2713, Qatar
| | - Michail Nomikos
- College of Medicine, QU Health, Qatar University, Doha P.O. Box 2713, Qatar;
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3
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Bhatt A, Ali ME. Understanding the role of R266K mutation in cystathionine β-synthase (CBS) enzyme: an in silico study. J Biomol Struct Dyn 2022; 40:12690-12698. [PMID: 34495791 DOI: 10.1080/07391102.2021.1975564] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Human cystathionine β-synthase (hCBS) is a Heme-containing, unique pyridoxal 5'-phosphate (PLP) dependent enzyme. CBS catalyzes the bio-chemical condensation reactions in the transsulfuration pathway. The role of Heme in the catalytic activities of the hCBS enzyme is still unknown, even though various experimental studies indicated its participation in the bi-directional electronic communication with the PLP center. The hypothesis is, Heme acts as an electron density reservoir for the catalytic reaction center rather than a redox electron source. In this work, we have investigated In Silico dynamical aspects of the bi-directional communications by performing classical molecular dynamics (MD) simulations upon developing the necessary force field parameters for the cysteine and histidine bound hexa-coordinated Heme. The comparative aspects, of electron density overlap across the communicating pathways, were investigated adopting the Density Functional Theory (DFT) in conjunction with the hybrid exchange-correlation functional for the CBSWT (wild-type) and CBSR266K (mutated) enzymes. The molecular dynamics simulations and subsequent explorations of the electronic structures confirm the reported observations. It also provides an in-depth mechanistic understanding of how the non-covalent hydrogen bonding interactions with Cys52 control such long-distance communication. Our study also provides a convincing answer to the reduced enzymatic activities in the R266K mutated hCBS compared to the wild-type enzymes. The difference in hydrogen-bonding patterns and salt-bridge interactions play the pivotal roles in such long distant bi-directional communications.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Aashish Bhatt
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, India
| | - Md Ehesan Ali
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, India
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4
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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.
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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
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5
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Khan FST, Samanta D, Chandel D, Shah SJ, Rath SP. Heme-Heme Interactions in Diheme Cytochromes: Effect of Mixed-Axial Ligation on the Electronic Structure and Electrochemical Properties. Inorg Chem 2021; 60:12870-12882. [PMID: 34370470 DOI: 10.1021/acs.inorgchem.1c01215] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Diheme cytochromes, the simplest members in the multiheme family, play substantial biochemical roles in enzymatic catalysis as well as in electron transfer. A series of diiron(III) porphyrin dimers have been synthesized as active site analogues of diheme cytochromes. The complexes contain six-coordinated iron(III) having thiophenol and imidazole at the fifth and sixth coordination sites, respectively. The iron centers in the complexes have been found to be in a low-spin state, as confirmed through solid-state Mössbauer and electron paramagnetic resonance (EPR) spectroscopic investigations. Mössbauer quadrupole splitting of complexes having mixed ligands is substantially larger than that observed when both axial ligands are the same. Rhombic types of EPR spectra with narrow separation between gx, gy, and gz clearly distinguish heme thiolate coordination compared to bis(imidazole)-ligated low-spin heme centers. The redox potential in diheme cytochromes has been found to be tuned by interheme interactions along with the nature of axial ligands. The effect of mixed-axial ligation within the diiron(III) porphyrin dimers is demonstrated by a positive shift in the Fe(III)/Fe(II) redox couple upon thiophenolate coordination compared to their bis(imidazole) analogues. The pKa of the imidazole also decides the extent of the shift for the Fe(III)/Fe(II) couple, while the potential of the mixed-ligated diiron(III) porphyrin dimer is more positive compared to their monomeric analogue. A variation of around 1.1 V for the Fe(III)/Fe(II) redox potential in the diiron(III) porphyrin dimer can be achieved with the combined effect of axial ligation and a metal spin state, while such a large variation in the redox potential, compared to their monomeric analogues, is attributed to the heme-heme interactions observed in dihemes. Moreover, theoretical calculations also support the experimental shifts in the redox potential values.
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Affiliation(s)
| | - Deepannita Samanta
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Dolly Chandel
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Syed Jehanger Shah
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Sankar Prasad Rath
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
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6
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Benchoam D, Cuevasanta E, Julió Plana L, Capece L, Banerjee R, Alvarez B. Heme-Thiolate Perturbation in Cystathionine β-Synthase by Mercury Compounds. ACS OMEGA 2021; 6:2192-2205. [PMID: 33521459 PMCID: PMC7841933 DOI: 10.1021/acsomega.0c05475] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 12/22/2020] [Indexed: 05/11/2023]
Abstract
Cystathionine β-synthase (CBS) is an enzyme involved in sulfur metabolism that catalyzes the pyridoxal phosphate-dependent condensation of homocysteine with serine or cysteine to form cystathionine and water or hydrogen sulfide (H2S), respectively. CBS possesses a b-type heme coordinated by histidine and cysteine. Fe(III)-CBS is inert toward exogenous ligands, while Fe(II)-CBS is reactive. Both Fe(III)- and Fe(II)-CBS are sensitive to mercury compounds. In this study, we describe the kinetics of the reactions with mercuric chloride (HgCl2) and p-chloromercuribenzoic acid. These reactions were multiphasic and resulted in five-coordinate CBS lacking thiolate ligation, with six-coordinate species as intermediates. Computational QM/MM studies supported the feasibility of formation of species in which the thiolate is proximal to both the iron ion and the mercury compound. The reactions of Fe(II)-CBS were faster than those of Fe(III)-CBS. The observed rate constants of the first phase increased hyperbolically with concentration of the mercury compounds, with limiting values of 0.3-0.4 s-1 for Fe(III)-CBS and 40 ± 4 s-1 for Fe(II)-CBS. The data were interpreted in terms of alternative models of conformational selection or induced fit. Exposure of Fe(III)-CBS to HgCl2 led to heme release and activity loss. Our study reveals the complexity of the interactions between mercury compounds and CBS.
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Affiliation(s)
- Dayana Benchoam
- Laboratorio
de Enzimología, Instituto de Química Biológica,
Facultad de Ciencias, Universidad de la
República, Montevideo, 11400 Uruguay
- Centro
de Investigaciones Biomédicas (CEINBIO), Universidad de la República, Montevideo, 11800 Uruguay
| | - Ernesto Cuevasanta
- Laboratorio
de Enzimología, Instituto de Química Biológica,
Facultad de Ciencias, Universidad de la
República, Montevideo, 11400 Uruguay
- Centro
de Investigaciones Biomédicas (CEINBIO), Universidad de la República, Montevideo, 11800 Uruguay
- Unidad
de Bioquímica Analítica, Centro de Investigaciones Nucleares,
Facultad de Ciencias, Universidad de la
República, Montevideo, 11400 Uruguay
| | - Laia Julió Plana
- Departamento
de Química Inorgánica, Analítica y Química
Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires/Instituto de Química
Física de los Materiales, Medio Ambiente y Energía (INQUIMAE-CONICET), C1428EGA Buenos
Aires, Argentina
| | - Luciana Capece
- Departamento
de Química Inorgánica, Analítica y Química
Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires/Instituto de Química
Física de los Materiales, Medio Ambiente y Energía (INQUIMAE-CONICET), C1428EGA Buenos
Aires, Argentina
| | - Ruma Banerjee
- Department
of Biological Chemistry, University of Michigan
Medical School, Ann Arbor, Michigan 48109, United States
| | - Beatriz Alvarez
- Laboratorio
de Enzimología, Instituto de Química Biológica,
Facultad de Ciencias, Universidad de la
República, Montevideo, 11400 Uruguay
- Centro
de Investigaciones Biomédicas (CEINBIO), Universidad de la República, Montevideo, 11800 Uruguay
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7
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Dent MR, Milbauer MW, Hunt AP, Aristov MM, Guzei IA, Lehnert N, Burstyn JN. Electron Paramagnetic Resonance Spectroscopy as a Probe of Hydrogen Bonding in Heme-Thiolate Proteins. Inorg Chem 2019; 58:16011-16027. [DOI: 10.1021/acs.inorgchem.9b02506] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Matthew R. Dent
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Michael W. Milbauer
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Andrew P. Hunt
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Michael M. Aristov
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Ilia A. Guzei
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Nicolai Lehnert
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Judith N. Burstyn
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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8
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Tavares NK, Stracey N, Brunold TC, Escalante-Semerena JC. The l-Thr Kinase/l-Thr-Phosphate Decarboxylase (CobD) Enzyme from Methanosarcina mazei Gö1 Contains Metallocenters Needed for Optimal Activity. Biochemistry 2019; 58:3260-3279. [PMID: 31268299 PMCID: PMC6667302 DOI: 10.1021/acs.biochem.9b00268] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The MM2060 (cobD) gene from Methanosarcina mazei strain Gö1 encodes a protein (MmCobD) with l-threonine kinase (PduX) and l-threonine-O-3-phosphate decarboxylase (CobD) activities. In addition to the unexpected l-Thr kinase activity, MmCobD has an extended carboxy-terminal (C-terminal) region annotated as a putative metal-binding zinc finger-like domain. Here, we demonstrate that the C-terminus of MmCobD is a ferroprotein containing ∼25 non-heme iron atoms per monomer of protein. The absence of the C-terminus substantially reduces, but does not abolish, enzymatic activities in vitro and in vivo. Single-residue substitutions of C-terminal putative Fe-binding cysteinyl and histidinyl residues resulted in the loss of Fe and changes in enzyme activity levels. Salmonella enterica ΔpduX and ΔcobD strains were used as heterologous hosts to assess coenzyme B12 biosynthesis as a function of 17 MmCobD variants tested. Some of the latter displayed 5-fold higher enzymatic activity in vitro and enhanced the growth rate of the S. enterica strains that synthesized them. Most of the MmCobD variants tested were up to 6-fold less active in vitro and supported slow growth rates of the S. enterica strains that synthesized them; some substitutions abolished enzyme activity. MmCobD exhibited an ultraviolet-visible absorption spectrum consistent with [4Fe-4S] clusters that appeared to be susceptible to oxidation by H2O2 and reduction by sodium dithionite. The presence of FeS clusters in MmCobD was corroborated by electron paramagnetic resonance and magnetic circular dichroism studies. Collectively, our results suggest that MmCobD contains one or more diamagnetic [4Fe-4S]2+ center(s) that may play a structural or regulatory role.
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Affiliation(s)
- Norbert K. Tavares
- Department of Microbiology, University of Georgia, Athens, Georgia 30602, USA
| | - Nuru Stracey
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706 USA
| | - Thomas C Brunold
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706 USA
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9
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Hydrogen Sulfide Biochemistry and Interplay with Other Gaseous Mediators in Mammalian Physiology. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:6290931. [PMID: 30050658 PMCID: PMC6040266 DOI: 10.1155/2018/6290931] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 03/13/2018] [Indexed: 01/06/2023]
Abstract
Hydrogen sulfide (H2S) has emerged as a relevant signaling molecule in physiology, taking its seat as a bona fide gasotransmitter akin to nitric oxide (NO) and carbon monoxide (CO). After being merely regarded as a toxic poisonous molecule, it is now recognized that mammalian cells are equipped with sophisticated enzymatic systems for H2S production and breakdown. The signaling role of H2S is mainly related to its ability to modify different protein targets, particularly by promoting persulfidation of protein cysteine residues and by interacting with metal centers, mostly hemes. H2S has been shown to regulate a myriad of cellular processes with multiple physiological consequences. As such, dysfunctional H2S metabolism is increasingly implicated in different pathologies, from cardiovascular and neurodegenerative diseases to cancer. As a highly diffusible reactive species, the intra- and extracellular levels of H2S have to be kept under tight control and, accordingly, regulation of H2S metabolism occurs at different levels. Interestingly, even though H2S, NO, and CO have similar modes of action and parallel regulatory targets or precisely because of that, there is increasing evidence of a crosstalk between the three gasotransmitters. Herein are reviewed the biochemistry, metabolism, and signaling function of hydrogen sulfide, as well as its interplay with the other gasotransmitters, NO and CO.
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10
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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: 562] [Impact Index Per Article: 93.7] [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.
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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
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11
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Gupta S, Wang L, Kruger WD. The c.797 G>A (p.R266K) cystathionine β-synthase mutation causes homocystinuria by affecting protein stability. Hum Mutat 2017; 38:863-869. [PMID: 28488385 DOI: 10.1002/humu.23240] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 04/27/2017] [Accepted: 04/28/2017] [Indexed: 11/10/2022]
Abstract
Mutations in the cystathionine beta-synthase (CBS) gene are the cause of classical homocystinuria, the most common inborn error in sulfur metabolism. The c.797 G>A (p.R266K) mutation in CBS was originally described in several Norwegian pyridoxine responsive CBS deficient patients, and heterologous gene expression studies have shown that the protein has near wild-type levels of enzyme activity. Here, we characterize a transgenic mouse lacking endogenous Cbs and expressing p.R266K human CBS protein from a zinc inducible metallothionein promoter (Tg-R266K Cbs-/- ). Unlike mice expressing other mutant CBS alleles, the Tg-R266K transgene is unable to efficiently rescue neonatal lethality of Cbs-/- on a C57BL/6J background. On a C3H/HeJ background, zinc-induced Tg-R266K Cbs-/- mice express CBS mRNA, but have very low levels of CBS protein and enzyme activity, resulting in extreme elevations in serum total homocysteine (tHcy). Treatment with pyridoxine did not have any appreciable effect on tHcy, indicating this allele is not pyridoxine responsive in mice. However, treatment with the proteasome inhibitor bortezomib resulted in an 97% reduction in tHcy and a 2381% increase in liver CBS activity. These studies show that the p.R266K mutation causes increased proteasomal degradation in vivo, and that treatments that stabilize the protein can be used to reverse its effect.
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Affiliation(s)
- Sapna Gupta
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Liqun Wang
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Warren D Kruger
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
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12
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A Clinically Relevant Variant of the Human Hydrogen Sulfide-Synthesizing Enzyme Cystathionine β-Synthase: Increased CO Reactivity as a Novel Molecular Mechanism of Pathogenicity? OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:8940321. [PMID: 28421128 PMCID: PMC5381205 DOI: 10.1155/2017/8940321] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 01/10/2017] [Accepted: 01/16/2017] [Indexed: 12/21/2022]
Abstract
The human disease classical homocystinuria results from mutations in the gene encoding the pyridoxal 5′-phosphate- (PLP-) dependent cystathionine β-synthase (CBS), a key enzyme in the transsulfuration pathway that controls homocysteine levels, and is a major source of the signaling molecule hydrogen sulfide (H2S). CBS activity, contributing to cellular redox homeostasis, is positively regulated by S-adenosyl-L-methionine (AdoMet) but fully inhibited upon CO or NO• binding to a noncatalytic heme moiety. Despite extensive studies, the molecular basis of several pathogenic CBS mutations is not yet fully understood. Here we found that the ferrous heme of the reportedly mild p.P49L CBS variant has altered spectral properties and markedly increased affinity for CO, making the protein much more prone than wild type (WT) CBS to inactivation at physiological CO levels. The higher CO affinity could result from the slightly higher flexibility in the heme surroundings revealed by solving at 2.80-Å resolution the crystallographic structure of a truncated p.P49L. Additionally, we report that p.P49L displays impaired H2S-generating activity, fully rescued by PLP supplementation along the purification, despite a minor responsiveness to AdoMet. Altogether, the results highlight how increased propensity to CO inactivation of an otherwise WT-like variant may represent a novel pathogenic mechanism in classical homocystinuria.
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13
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Vicente JB, Malagrinò F, Arese M, Forte E, Sarti P, Giuffrè A. Bioenergetic relevance of hydrogen sulfide and the interplay between gasotransmitters at human cystathionine β-synthase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1127-1138. [PMID: 27039165 DOI: 10.1016/j.bbabio.2016.03.030] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 03/07/2016] [Accepted: 03/28/2016] [Indexed: 12/27/2022]
Abstract
Merely considered as a toxic gas in the past, hydrogen sulfide (H2S) is currently viewed as the third 'gasotransmitter' in addition to nitric oxide (NO) and carbon monoxide (CO), playing a key signalling role in human (patho)physiology. H2S can either act as a substrate or, similarly to CO and NO, an inhibitor of mitochondrial respiration, in the latter case by targeting cytochrome c oxidase (CcOX). The impact of H(2)S on mitochondrial energy metabolism crucially depends on the bioavailability of this gaseous molecule and its interplay with the other two gasotransmitters. The H(2)S-producing human enzyme cystathionine β-synthase (CBS), sustaining cellular bioenergetics in colorectal cancer cells, plays a role in the interplay between gasotransmitters. The enzyme was indeed recently shown to be negatively modulated by physiological concentrations of CO and NO, particularly in the presence of its allosteric activator S-adenosyl-l-methionine (AdoMet). These newly discovered regulatory mechanisms are herein reviewed. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.
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Affiliation(s)
- João B Vicente
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República (EAN), 2780-156 Oeiras, Portugal.
| | - Francesca Malagrinò
- Department of Biochemical Sciences and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Marzia Arese
- Department of Biochemical Sciences and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Elena Forte
- Department of Biochemical Sciences and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Paolo Sarti
- Department of Biochemical Sciences and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Alessandro Giuffrè
- CNR Institute of Molecular Biology and Pathology, Piazzale Aldo Moro 5, I-00185 Rome, Italy.
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14
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Carballal S, Cuevasanta E, Yadav PK, Gherasim C, Ballou DP, Alvarez B, Banerjee R. Kinetics of Nitrite Reduction and Peroxynitrite Formation by Ferrous Heme in Human Cystathionine β-Synthase. J Biol Chem 2016; 291:8004-13. [PMID: 26867575 DOI: 10.1074/jbc.m116.718734] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Indexed: 01/01/2023] Open
Abstract
Cystathionine β-synthase (CBS) is a pyridoxal phosphate-dependent enzyme that catalyzes the condensation of homocysteine with serine or with cysteine to form cystathionine and either water or hydrogen sulfide, respectively. Human CBS possesses a noncatalytic heme cofactor with cysteine and histidine as ligands, which in its oxidized state is relatively unreactive. Ferric CBS (Fe(III)-CBS) can be reduced by strong chemical and biochemical reductants to Fe(II)-CBS, which can bind carbon monoxide (CO) or nitric oxide (NO(•)), leading to inactive enzyme. Alternatively, Fe(II)-CBS can be reoxidized by O2to Fe(III)-CBS, forming superoxide radical anion (O2 (̇̄)). In this study, we describe the kinetics of nitrite (NO2 (-)) reduction by Fe(II)-CBS to form Fe(II)NO(•)-CBS. The second order rate constant for the reaction of Fe(II)-CBS with nitrite was obtained at low dithionite concentrations. Reoxidation of Fe(II)NO(•)-CBS by O2showed complex kinetic behavior and led to peroxynitrite (ONOO(-)) formation, which was detected using the fluorescent probe, coumarin boronic acid. Thus, in addition to being a potential source of superoxide radical, CBS constitutes a previously unrecognized source of NO(•)and peroxynitrite.
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Affiliation(s)
- Sebastián Carballal
- From the Departamento de Bioquímica, Facultad de Medicina, Center for Free Radical and Biomedical Research, and
| | - Ernesto Cuevasanta
- Center for Free Radical and Biomedical Research, and Laboratorio de Enzimología, Facultad de Ciencias, Universidad de la República, Montevideo 11800, Uruguay and
| | - Pramod K Yadav
- the Department of Biological Chemistry, Medical Center, University of Michigan, Ann Arbor, Michigan 48109-0600
| | - Carmen Gherasim
- the Department of Biological Chemistry, Medical Center, University of Michigan, Ann Arbor, Michigan 48109-0600
| | - David P Ballou
- the Department of Biological Chemistry, Medical Center, University of Michigan, Ann Arbor, Michigan 48109-0600
| | - Beatriz Alvarez
- Center for Free Radical and Biomedical Research, and Laboratorio de Enzimología, Facultad de Ciencias, Universidad de la República, Montevideo 11800, Uruguay and
| | - Ruma Banerjee
- the Department of Biological Chemistry, Medical Center, University of Michigan, Ann Arbor, Michigan 48109-0600
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15
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Vicente JB, Colaço HG, Sarti P, Leandro P, Giuffrè A. S-Adenosyl-l-methionine Modulates CO and NO• Binding to the Human H2S-generating Enzyme Cystathionine β-Synthase. J Biol Chem 2015; 291:572-81. [PMID: 26582199 DOI: 10.1074/jbc.m115.681221] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Indexed: 01/11/2023] Open
Abstract
Cystathionine β-synthase (CBS) is a key enzyme in human (patho)physiology with a central role in hydrogen sulfide metabolism. The enzyme is composed of a pyridoxal 5'-phosphate-binding catalytic domain, flanked by the following two domains: a heme-binding N-terminal domain and a regulatory C-terminal domain binding S-adenosyl-l-methionine (AdoMet). CO or NO(•) binding at the ferrous heme negatively modulates the enzyme activity. Conversely, AdoMet binding stimulates CBS activity. Here, we provide experimental evidence for a functional communication between the two domains. We report that AdoMet binding significantly enhances CBS inhibition by CO. Consistently, we observed increased affinity (∼5-fold) and faster association (∼10-fold) of CO to the ferrous heme at physiological AdoMet concentrations. NO(•) binding to reduced CBS was also enhanced by AdoMet, although to a lesser extent (∼2-fold higher affinity) as compared with CO. Importantly, CO and NO(•) binding was unchanged by AdoMet in a truncated form of CBS lacking the C-terminal regulatory domain. These unprecedented observations demonstrate that CBS activation by AdoMet puzzlingly sensitizes the enzyme toward inhibition by exogenous ligands, like CO and NO(•). This further supports the notion that CBS regulation is a complex process, involving the concerted action of multiple physiologically relevant effectors.
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Affiliation(s)
- João B Vicente
- From the Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2781-156 Oeiras, Portugal,
| | - Henrique G Colaço
- the Metabolism and Genetics Group, Research Institute for Medicines, Faculty of Pharmacy, University of Lisbon, 1649-003 Lisbon, Portugal
| | - Paolo Sarti
- the Department of Biochemical Sciences and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, I-00185 Rome, Italy
| | - Paula Leandro
- the Metabolism and Genetics Group, Research Institute for Medicines, Faculty of Pharmacy, University of Lisbon, 1649-003 Lisbon, Portugal, the Department of Biochemistry and Human Biology, Faculty of Pharmacy, University of Lisbon, 1640-003 Lisbon, Portugal, and
| | - Alessandro Giuffrè
- the Institute of Molecular Biology and Pathology, National Research Council of Italy, I-00185 Rome, Italy
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16
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Shimizu T, Huang D, Yan F, Stranava M, Bartosova M, Fojtíková V, Martínková M. Gaseous O2, NO, and CO in signal transduction: structure and function relationships of heme-based gas sensors and heme-redox sensors. Chem Rev 2015; 115:6491-533. [PMID: 26021768 DOI: 10.1021/acs.chemrev.5b00018] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Toru Shimizu
- †Department of Cell Biology and Genetics and Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Chaoshan Area of Guangdong Higher Education Institutes, Shantou University Medical College, Shantou, Guangdong 515041, China
- ‡Department of Biochemistry, Faculty of Science, Charles University in Prague, Prague 2 128 43, Czech Republic
- §Research Center for Compact Chemical System, National Institute of Advanced Industrial Science and Technology (AIST), Sendai 983-8551, Japan
| | - Dongyang Huang
- †Department of Cell Biology and Genetics and Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Chaoshan Area of Guangdong Higher Education Institutes, Shantou University Medical College, Shantou, Guangdong 515041, China
| | - Fang Yan
- †Department of Cell Biology and Genetics and Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Chaoshan Area of Guangdong Higher Education Institutes, Shantou University Medical College, Shantou, Guangdong 515041, China
| | - Martin Stranava
- ‡Department of Biochemistry, Faculty of Science, Charles University in Prague, Prague 2 128 43, Czech Republic
| | - Martina Bartosova
- ‡Department of Biochemistry, Faculty of Science, Charles University in Prague, Prague 2 128 43, Czech Republic
| | - Veronika Fojtíková
- ‡Department of Biochemistry, Faculty of Science, Charles University in Prague, Prague 2 128 43, Czech Republic
| | - Markéta Martínková
- ‡Department of Biochemistry, Faculty of Science, Charles University in Prague, Prague 2 128 43, Czech Republic
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17
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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
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18
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Melenovská P, Kopecká J, Krijt J, Hnízda A, Raková K, Janošík M, Wilcken B, Kožich V. Chaperone therapy for homocystinuria: the rescue of CBS mutations by heme arginate. J Inherit Metab Dis 2015; 38:287-94. [PMID: 25331909 DOI: 10.1007/s10545-014-9781-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 10/02/2014] [Accepted: 10/06/2014] [Indexed: 02/01/2023]
Abstract
Classical homocystinuria is caused by mutations in the cystathionine β-synthase (CBS) gene. Previous experiments in bacterial and yeast cells showed that many mutant CBS enzymes misfold and that chemical chaperones enable proper folding of a number of mutations. In the present study, we tested the extent of misfolding of 27 CBS mutations previously tested in E. coli under the more folding-permissive conditions of mammalian CHO-K1 cells and the ability of chaperones to rescue the conformation of these mutations. Expression of mutations in mammalian cells increased the median activity 16-fold and the amount of tetramers 3.2-fold compared with expression in bacteria. Subsequently, we tested the responses of seven selected mutations to three compounds with chaperone-like activity. Aminooxyacetic acid and 4-phenylbutyric acid exhibited only a weak effect. In contrast, heme arginate substantially increased the formation of mutant CBS protein tetramers (up to sixfold) and rescued catalytic activity (up to ninefold) of five out of seven mutations (p.A114V, p.K102N, p.R125Q, p.R266K, and p.R369C). The greatest effect of heme arginate was observed for the mutation p.R125Q, which is non-responsive to in vivo treatment with vitamin B(6). Moreover, the heme responsiveness of the p.R125Q mutation was confirmed in fibroblasts derived from a patient homozygous for this genetic variant. Based on these data, we propose that a distinct group of heme-responsive CBS mutations may exist and that the heme pocket of CBS may become an important target for designing novel therapies for homocystinuria.
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Affiliation(s)
- Petra Melenovská
- Institute of Inherited Metabolic Disorders, Charles University in Prague-First Faculty of Medicine and General University Hospital in Prague, Ke Karlovu 2, 128 08, Praha 2, Czech Republic
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19
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Muntau AC, Leandro J, Staudigl M, Mayer F, Gersting SW. Innovative strategies to treat protein misfolding in inborn errors of metabolism: pharmacological chaperones and proteostasis regulators. J Inherit Metab Dis 2014; 37:505-23. [PMID: 24687294 DOI: 10.1007/s10545-014-9701-z] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 02/19/2014] [Accepted: 02/24/2014] [Indexed: 10/25/2022]
Abstract
To attain functionality, proteins must fold into their three-dimensional native state. The intracellular balance between protein synthesis, folding, and degradation is constantly challenged by genetic or environmental stress factors. In the last ten years, protein misfolding induced by missense mutations was demonstrated to be the seminal molecular mechanism in a constantly growing number of inborn errors of metabolism. In these cases, loss of protein function results from early degradation of missense-induced misfolded proteins. Increasing knowledge on the proteostasis network and the protein quality control system with distinct mechanisms in different compartments of the cell paved the way for the development of new treatment strategies for conformational diseases using small molecules. These comprise proteostasis regulators that enhance the capacity of the proteostasis network and pharmacological chaperones that specifically bind and rescue misfolded proteins by conformational stabilization. They can be used either alone or in combination, the latter to exploit synergistic effects. Many of these small molecule compounds currently undergo preclinical and clinical pharmaceutical development and two have been approved: saproterin dihydrochloride for the treatment of phenylketonuria and tafamidis for the treatment of transthyretin-related hereditary amyloidosis. Different technologies are exploited for the discovery of new small molecule compounds that belong to the still young class of pharmaceutical products discussed here. These compounds may in the near future improve existing treatment strategies or even offer a first-time treatment to patients suffering from nowadays-untreatable inborn errors of metabolism.
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Affiliation(s)
- Ania C Muntau
- Department of Molecular Pediatrics, Dr von Hauner Children's Hospital, Ludwig Maximilians University, Lindwurmstrasse 4, 80337, Munich, Germany,
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20
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Mendes MIS, Colaço HG, Smith DEC, Ramos RJJF, Pop A, van Dooren SJM, Tavares de Almeida I, Kluijtmans LAJ, Janssen MCH, Rivera I, Salomons GS, Leandro P, Blom HJ. Reduced response of Cystathionine Beta-Synthase (CBS) to S-Adenosylmethionine (SAM): Identification and functional analysis of CBS gene mutations in Homocystinuria patients. J Inherit Metab Dis 2014; 37:245-54. [PMID: 23974653 DOI: 10.1007/s10545-013-9647-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 07/29/2013] [Accepted: 07/30/2013] [Indexed: 11/29/2022]
Abstract
A reduced response of cystathionine beta-synthase (CBS) to its allosteric activator S-adenosylmethionine (SAM) has been reported to be a cause of CBS dysfunction in homocystinuria patients. In this work we performed a retrospective analysis of fibroblast data from 62 homocystinuria patients and found that 13 of them presented a disturbed SAM activation. Their genotypic background was identified and the corresponding CBS mutant proteins were produced in E. coli. Nine distinct mutations were detected in 22 independent alleles: the novel mutations p.K269del, p.P427L, p.S500L and p.L540Q; and the previously described mutations p.P49L, p.C165Rfs*2, p.I278T, p.R336H and p.D444N. Expression levels and residual enzyme activities, determined in the soluble fraction of E. coli lysates, strongly correlated with the localization of the affected amino acid residue. C-terminal mutations lead to activities in the range of the wild-type CBS and to oligomeric forms migrating faster than tetramers, suggesting an abnormal conformation that might be responsible for the lack of SAM activation. Mutations in the catalytic core were associated with low protein expression levels, decreased enzyme activities and a higher content of high molecular mass forms. Furthermore, the absence of SAM activation found in the patients' fibroblasts was confirmed for all but one of the characterized recombinant proteins (p.P49L). Our study experimentally supports a deficient regulation of CBS by SAM as a frequently found mechanism in CBS deficiency, which should be considered not only as a valuable diagnostic tool but also as a potential target for the development of new therapeutic approaches in classical homocystinuria.
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Affiliation(s)
- Marisa I S Mendes
- Metabolism and Genetics Group, Research Institute for Medicines and Pharmaceutical Sciences, Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
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21
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Vicente JB, Colaço HG, Mendes MIS, Sarti P, Leandro P, Giuffrè A. NO* binds human cystathionine β-synthase quickly and tightly. J Biol Chem 2014; 289:8579-87. [PMID: 24515102 DOI: 10.1074/jbc.m113.507533] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The hexa-coordinate heme in the H2S-generating human enzyme cystathionine β-synthase (CBS) acts as a redox-sensitive regulator that impairs CBS activity upon binding of NO(•) or CO at the reduced iron. Despite the proposed physiological relevance of this inhibitory mechanism, unlike CO, NO(•) was reported to bind at the CBS heme with very low affinity (Kd = 30-281 μm). This discrepancy was herein reconciled by investigating the NO(•) reactivity of recombinant human CBS by static and stopped-flow UV-visible absorption spectroscopy. We found that NO(•) binds tightly to the ferrous CBS heme, with an apparent Kd ≤ 0.23 μm. In line with this result, at 25 °C, NO(•) binds quickly to CBS (k on ∼ 8 × 10(3) m(-1) s(-1)) and dissociates slowly from the enzyme (k off ∼ 0.003 s(-1)). The observed rate constants for NO(•) binding were found to be linearly dependent on [NO(•)] up to ∼ 800 μm NO(•), and >100-fold higher than those measured for CO, indicating that the reaction is not limited by the slow dissociation of Cys-52 from the heme iron, as reported for CO. For the first time the heme of human CBS is reported to bind NO(•) quickly and tightly, providing a mechanistic basis for the in vivo regulation of the enzyme by NO(•). The novel findings reported here shed new light on CBS regulation by NO(•) and its possible (patho)physiological relevance, enforcing the growing evidence for an interplay among the gasotransmitters NO(•), CO, and H2S in cell signaling.
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Affiliation(s)
- João B Vicente
- From the Metabolism and Genetics Group, Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculty of Pharmacy, University of Lisbon, 1649-003 Lisbon, Portugal
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22
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Pey AL. Protein homeostasis disorders of key enzymes of amino acids metabolism: mutation-induced protein kinetic destabilization and new therapeutic strategies. Amino Acids 2013; 45:1331-41. [PMID: 24178766 DOI: 10.1007/s00726-013-1609-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 10/19/2013] [Indexed: 12/31/2022]
Abstract
Many inborn errors of amino acids metabolism are caused by single point mutations affecting the ability of proteins to fold properly (i.e., protein homeostasis), thus leading to enzyme loss-of-function. Mutations may affect protein homeostasis by altering intrinsic physical properties of the polypeptide (folding thermodynamics, and rates of folding/unfolding/misfolding) as well as the interaction of partially folded states with elements of the protein homeostasis network (such as molecular chaperones and proteolytic machineries). Understanding these mutational effects on protein homeostasis is required to develop new therapeutic strategies aimed to target specific features of the mutant polypeptide. Here, I review recent work in three different diseases of protein homeostasis associated to inborn errors of amino acids metabolism: phenylketonuria, inherited homocystinuria and primary hyperoxaluria type I. These three different genetic disorders involve proteins operating in different cell organelles and displaying different structural complexities. Mutations often decrease protein kinetic stability of the native state (i.e., its half-life for irreversible denaturation), which can be studied using simple kinetic models amenable to biophysical and biochemical characterization. Natural ligands and pharmacological chaperones are shown to stabilize mutant enzymes, thus supporting their therapeutic application to overcome protein kinetic destabilization. The role of molecular chaperones in protein folding and misfolding is also discussed as well as their potential pharmacological modulation as promising new therapeutic approaches. Since current available treatments for these diseases are either burdening or only successful in a fraction of patients, alternative treatments must be considered covering studies from protein structure and biophysics to studies in animal models and patients.
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Affiliation(s)
- Angel L Pey
- Department of Physical Chemistry, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, 18071, Granada, Spain,
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23
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Stefl S, Nishi H, Petukh M, Panchenko AR, Alexov E. Molecular mechanisms of disease-causing missense mutations. J Mol Biol 2013; 425:3919-36. [PMID: 23871686 DOI: 10.1016/j.jmb.2013.07.014] [Citation(s) in RCA: 187] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 07/04/2013] [Accepted: 07/10/2013] [Indexed: 12/23/2022]
Abstract
Genetic variations resulting in a change of amino acid sequence can have a dramatic effect on stability, hydrogen bond network, conformational dynamics, activity and many other physiologically important properties of proteins. The substitutions of only one residue in a protein sequence, so-called missense mutations, can be related to many pathological conditions and may influence susceptibility to disease and drug treatment. The plausible effects of missense mutations range from affecting the macromolecular stability to perturbing macromolecular interactions and cellular localization. Here we review the individual cases and genome-wide studies that illustrate the association between missense mutations and diseases. In addition, we emphasize that the molecular mechanisms of effects of mutations should be revealed in order to understand the disease origin. Finally, we report the current state-of-the-art methodologies that predict the effects of mutations on protein stability, the hydrogen bond network, pH dependence, conformational dynamics and protein function.
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Affiliation(s)
- Shannon Stefl
- Computational Biophysics and Bioinformatics, Department of Physics, Clemson University, Clemson, SC 29634, USA
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24
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Carballal S, Cuevasanta E, Marmisolle I, Kabil O, Gherasim C, Ballou DP, Banerjee R, Alvarez B. Kinetics of reversible reductive carbonylation of heme in human cystathionine β-synthase. Biochemistry 2013; 52:4553-62. [PMID: 23790103 DOI: 10.1021/bi4004556] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Cystathionine β-synthase (CBS) catalyzes the condensation of homocysteine with serine or cysteine to form cystathionine and water or hydrogen sulfide (H2S), respectively. In addition to pyridoxal phosphate, human CBS has a heme cofactor with cysteine and histidine as ligands. While Fe(III)-CBS is inert to exogenous ligands, Fe(II)-CBS can be reversibly inhibited by carbon monoxide (CO) and reoxidized by O2 to yield superoxide radical. In this study, we have examined the kinetics of Fe(II)CO-CBS formation and reoxidation. Reduction of Fe(III)-CBS by dithionite showed a square root dependence on concentration, indicating that the reductant species was the sulfur dioxide radical anion (SO2(•-)) that exists in rapid equilibrium with S2O4(2-). Formation of Fe(II)CO-CBS from Fe(II)-CBS and 1 mM CO occurred with a rate constant of (3.1 ± 0.4) × 10(-3) s(-1) (pH 7.4, 25 °C). The reaction of Fe(III)-CBS with the reduced form of the flavoprotein methionine synthase reductase in the presence of CO and NADPH resulted in its reduction and carbonylation to form Fe(II)CO-CBS. Fe(II)-CBS was formed as an intermediate with a rate constant of (9.3 ± 2.5) × 10(2) M(-1) s(-1). Reoxidation of Fe(II)CO-CBS by O2 was multiphasic. The major phase showed a hyperbolic dependence on O2 concentration. Although H2S is a product of the CBS reaction and a potential heme ligand, we did not find evidence of an effect of exogenous H2S on activity or heme binding. Reversible reduction of CBS by a physiologically relevant oxidoreductase is consistent with a regulatory role for the heme and could constitute a mechanism for cross talk among the CO, H2S, and superoxide signaling pathways.
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Affiliation(s)
- Sebastián Carballal
- Laboratorio de Enzimología, Facultad de Ciencias, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
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25
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Sengupta K, Chatterjee S, Samanta S, Bandyopadhyay S, Dey A. Resonance Raman and Electrocatalytic Behavior of Thiolate and Imidazole Bound Iron Porphyrin Complexes on Self Assembled Monolayers: Functional Modeling of Cytochrome P450. Inorg Chem 2013; 52:2000-14. [DOI: 10.1021/ic302369v] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Kushal Sengupta
- Department of Inorganic Chemistry, Indian Association for the Cultivation of Science,
Kolkata, India 700032
| | - Sudipta Chatterjee
- Department of Inorganic Chemistry, Indian Association for the Cultivation of Science,
Kolkata, India 700032
| | - Subhra Samanta
- Department of Inorganic Chemistry, Indian Association for the Cultivation of Science,
Kolkata, India 700032
| | - Sabyasachi Bandyopadhyay
- Department of Inorganic Chemistry, Indian Association for the Cultivation of Science,
Kolkata, India 700032
| | - Abhishek Dey
- Department of Inorganic Chemistry, Indian Association for the Cultivation of Science,
Kolkata, India 700032
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