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Pedretti M, Fernández-Rodríguez C, Conter C, Oyenarte I, Favretto F, di Matteo A, Dominici P, Petrosino M, Martinez-Chantar ML, Majtan T, Astegno A, Martínez-Cruz LA. Catalytic specificity and crystal structure of cystathionine γ-lyase from Pseudomonas aeruginosa. Sci Rep 2024; 14:9364. [PMID: 38654065 PMCID: PMC11039470 DOI: 10.1038/s41598-024-57625-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 03/20/2024] [Indexed: 04/25/2024] Open
Abstract
The escalating drug resistance among microorganisms underscores the urgent need for innovative therapeutic strategies and a comprehensive understanding of bacteria's defense mechanisms against oxidative stress and antibiotics. Among the recently discovered barriers, the endogenous production of hydrogen sulfide (H2S) via the reverse transsulfuration pathway, emerges as a noteworthy factor. In this study, we have explored the catalytic capabilities and crystal structure of cystathionine γ-lyase from Pseudomonas aeruginosa (PaCGL), a multidrug-opportunistic pathogen chiefly responsible for nosocomial infections. In addition to a canonical L-cystathionine hydrolysis, PaCGL efficiently catalyzes the production of H2S using L-cysteine and/or L-homocysteine as alternative substrates. Comparative analysis with the human enzyme and counterparts from other pathogens revealed distinct structural features within the primary enzyme cavities. Specifically, a distinctly folded entrance loop could potentially modulate the access of substrates and/or inhibitors to the catalytic site. Our findings offer significant insights into the structural evolution of CGL enzymes across different pathogens and provide novel opportunities for developing specific inhibitors targeting PaCGL.
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Affiliation(s)
- Marco Pedretti
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy
| | - Carmen Fernández-Rodríguez
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160, Derio, Spain
| | - Carolina Conter
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160, Derio, Spain
| | - Iker Oyenarte
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160, Derio, Spain
| | - Filippo Favretto
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy
| | - Adele di Matteo
- CNR Institute of Molecular Biology and Pathology, P.le Aldo Moro 5, 00185, Rome, Italy
| | - Paola Dominici
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy
| | - Maria Petrosino
- Department of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Chemin du Musee 18, Bldg. PER17, 1700, Fribourg, FR, Switzerland
| | - Maria Luz Martinez-Chantar
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160, Derio, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Santander, Spain
| | - Tomas Majtan
- Department of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Chemin du Musee 18, Bldg. PER17, 1700, Fribourg, FR, Switzerland
| | - Alessandra Astegno
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy.
| | - Luis Alfonso Martínez-Cruz
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160, Derio, Spain.
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Collard R, Majtan T. Genetic and Pharmacological Modulation of Cellular Proteostasis Leads to Partial Functional Rescue of Homocystinuria-Causing Cystathionine-Beta Synthase Variants. Mol Cell Biol 2023; 43:664-674. [PMID: 38051092 PMCID: PMC10761163 DOI: 10.1080/10985549.2023.2284147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 11/09/2023] [Indexed: 12/07/2023] Open
Abstract
Homocystinuria (HCU), an inherited metabolic disorder caused by lack of cystathionine beta-synthase (CBS) activity, is chiefly caused by misfolding of single amino acid residue missense pathogenic variants. Previous studies showed that chemical, pharmacological chaperones or proteasome inhibitors could rescue function of multiple pathogenic CBS variants; however, the underlying mechanisms remain poorly understood. Using Chinese hamster DON fibroblasts devoid of CBS and stably overexpressing human WT or mutant CBS, we showed that expression of pathogenic CBS variant mostly dysregulates gene expression of small heat shock proteins HSPB3 and HSPB8 and members of HSP40 family. Endoplasmic reticulum stress sensor BiP was found upregulated with CBS I278T variant associated with proteasomes suggesting proteotoxic stress and degradation of misfolded CBS. Co-expression of the main effector HSP70 or master regulator HSF1 rescued steady-state levels of CBS I278T and R125Q variants with partial functional rescue of the latter. Pharmacological proteostasis modulators partially rescued expression and activity of CBS R125Q likely due to reduced proteotoxic stress as indicated by decreased BiP levels and promotion of refolding as indicated by induction of HSP70. In conclusion, targeted manipulation of cellular proteostasis may represent a viable therapeutic approach for the permissive pathogenic CBS variants causing HCU.
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Affiliation(s)
- Renata Collard
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Tomas Majtan
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Department of Pharmacology, University of Fribourg, Faculty of Science and Medicine, Fribourg, Switzerland
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Majtan T, Kožich V, Kruger WD. Recent therapeutic approaches to cystathionine beta-synthase-deficient homocystinuria. Br J Pharmacol 2023; 180:264-278. [PMID: 36417581 PMCID: PMC9822868 DOI: 10.1111/bph.15991] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 11/09/2022] [Accepted: 11/14/2022] [Indexed: 11/27/2022] Open
Abstract
Cystathionine beta-synthase (CBS)-deficient homocystinuria (HCU) is the most common inborn error of sulfur amino acid metabolism. The pyridoxine non-responsive form of the disease manifests itself by massively increasing plasma and tissue concentrations of homocysteine, a toxic intermediate of methionine metabolism that is thought to be the major cause of clinical complications including skeletal deformities, connective tissue defects, thromboembolism and cognitive impairment. The current standard of care involves significant dietary interventions that, despite being effective, often adversely affect quality of life of HCU patients, leading to poor adherence to therapy and inadequate biochemical control with clinical complications. In recent years, the unmet need for better therapeutic options has resulted in development of novel enzyme and gene therapies and exploration of pharmacological approaches to rescue CBS folding defects caused by missense pathogenic mutations. Here, we review scientific evidence and current state of affairs in development of recent approaches to treat HCU.
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Affiliation(s)
- Tomas Majtan
- Department of Pharmacology, University of Fribourg, Faculty of Science and Medicine, Fribourg, 1700, Switzerland
| | - Viktor Kožich
- Department of Pediatrics and Inherited Metabolic Disorders, Charles University-First Faculty of Medicine, Prague, 12808, Czech Republic
- Department of Pediatrics and Inherited Metabolic Disorders, General University Hospital in Prague, Prague, 12808, Czech Republic
| | - Warren D. Kruger
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
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Zuhra K, Petrosino M, Gupta B, Panagaki T, Cecconi M, Myrianthopoulos V, Schneiter R, Mikros E, Majtan T, Szabo C. Epigallocatechin gallate is a potent inhibitor of cystathionine beta-synthase: Structure-activity relationship and mechanism of action. Nitric Oxide 2022; 128:12-24. [PMID: 35973674 DOI: 10.1016/j.niox.2022.07.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 07/22/2022] [Accepted: 07/28/2022] [Indexed: 10/31/2022]
Abstract
Epigallocatechin gallate (EGCG) is the main bioactive component of green tea. Through screening of a small library of natural compounds, we discovered that EGCG inhibits cystathionine β-synthase (CBS), a major H2S-generating enzyme. Here we characterize EGCG's mechanism of action in the context of CBS-derived H2S production. In the current project, biochemical, pharmacological and cell biology approaches were used to characterize the effect of EGCG on CBS in cellular models of cancer and Down syndrome (DS). The results show that EGCG binds to CBS and inhibits H2S-producing CBS activity almost 30-times more efficiently than the canonical cystathionine formation (IC50 0.12 versus 3.3 μM). Through screening structural analogs and building blocks, we identified that gallate moiety of EGCG represents the pharmacophore responsible for CBS inhibition. EGCG is a mixed-mode, CBS-specific inhibitor with no effect on the other two major enzymatic sources of H2S, CSE and 3-MST. Unlike the prototypical CBS inhibitor aminooxyacetate, EGCG does not bind the catalytic cofactor of CBS pyridoxal-5'-phosphate. Molecular modeling suggests that EGCG blocks a substrate access channel to pyridoxal-5'-phosphate. EGCG inhibits cellular H2S production in HCT-116 colon cancer cells and in DS fibroblasts. It also exerts effects that are consistent with the functional role of CBS in these cells: in HCT-116 cells it decreases, while in DS cells it improves viability and proliferation. In conclusion, EGCG is a potent inhibitor of CBS-derived H2S production. This effect may contribute to its pharmacological effects in various pathophysiological conditions.
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Affiliation(s)
- Karim Zuhra
- Chair of Pharmacology, University of Fribourg, Faculty of Science and Medicine, Chemin du Musee 18, Fribourg, 1700, Switzerland
| | - Maria Petrosino
- Chair of Pharmacology, University of Fribourg, Faculty of Science and Medicine, Chemin du Musee 18, Fribourg, 1700, Switzerland
| | - Barkha Gupta
- Department of Biology, University of Fribourg, Faculty of Science and Medicine, Chemin du Musee 10, Fribourg, 1700, Switzerland
| | - Theodora Panagaki
- Chair of Pharmacology, University of Fribourg, Faculty of Science and Medicine, Chemin du Musee 18, Fribourg, 1700, Switzerland
| | - Marco Cecconi
- Chair of Pharmacology, University of Fribourg, Faculty of Science and Medicine, Chemin du Musee 18, Fribourg, 1700, Switzerland
| | - Vassilios Myrianthopoulos
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Athens, Athens, 15772, Greece
| | - Roger Schneiter
- Department of Biology, University of Fribourg, Faculty of Science and Medicine, Chemin du Musee 10, Fribourg, 1700, Switzerland
| | - Emmanuel Mikros
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Athens, Athens, 15772, Greece
| | - Tomas Majtan
- Chair of Pharmacology, University of Fribourg, Faculty of Science and Medicine, Chemin du Musee 18, Fribourg, 1700, Switzerland.
| | - Csaba Szabo
- Chair of Pharmacology, University of Fribourg, Faculty of Science and Medicine, Chemin du Musee 18, Fribourg, 1700, Switzerland.
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Petrosino M, Zuhra K, Kopec J, Hutchin A, Szabo C, Majtan T. H 2S biogenesis by cystathionine beta-synthase: mechanism of inhibition by aminooxyacetic acid and unexpected role of serine. Cell Mol Life Sci 2022; 79:438. [PMID: 35864237 PMCID: PMC9304066 DOI: 10.1007/s00018-022-04479-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 06/28/2022] [Accepted: 07/06/2022] [Indexed: 12/19/2022]
Abstract
Cystathionine beta-synthase (CBS) is a pivotal enzyme of the transsulfuration pathway responsible for diverting homocysteine to the biosynthesis of cysteine and production of hydrogen sulfide (H2S). Aberrant upregulation of CBS and overproduction of H2S contribute to pathophysiology of several diseases including cancer and Down syndrome. Therefore, pharmacological CBS inhibition has emerged as a prospective therapeutic approach. Here, we characterized binding and inhibitory mechanism of aminooxyacetic acid (AOAA), the most commonly used CBS inhibitor. We found that AOAA binds CBS tighter than its respective substrates and forms a dead-end PLP-bound intermediate featuring an oxime bond. Surprisingly, serine, but not cysteine, replaced AOAA from CBS and formed an aminoacrylate reaction intermediate, which allowed for the continuation of the catalytic cycle. Indeed, serine rescued and essentially normalized the enzymatic activity of AOAA-inhibited CBS. Cellular studies confirmed that AOAA decreased H2S production and bioenergetics, while additional serine rescued CBS activity, H2S production and mitochondrial function. The crystal structure of AOAA-bound human CBS showed a lack of hydrogen bonding with residues G305 and Y308, found in the serine-bound model. Thus, AOAA-inhibited CBS could be reactivated by serine. This difference may be important in a cellular environment in multiple pathophysiological conditions and may modulate the CBS-inhibitory activity of AOAA. In addition, our results demonstrate additional complexities of using AOAA as a CBS-specific inhibitor of H2S biogenesis and point to the urgent need to develop a potent, selective and specific pharmacological CBS inhibitor.
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Affiliation(s)
- Maria Petrosino
- Department of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Chemin du Musee 18, PER17, 1700, Fribourg, Switzerland
| | - Karim Zuhra
- Department of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Chemin du Musee 18, PER17, 1700, Fribourg, Switzerland
| | - Jola Kopec
- Structural Biology Unit, Evotec Ltd, 114 Innovation Drive, Abingdon, OX14 4RZ, UK
| | - Andrew Hutchin
- Structural Biology Unit, Evotec Ltd, 114 Innovation Drive, Abingdon, OX14 4RZ, UK
| | - Csaba Szabo
- Department of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Chemin du Musee 18, PER17, 1700, Fribourg, Switzerland
| | - Tomas Majtan
- Department of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Chemin du Musee 18, PER17, 1700, Fribourg, Switzerland.
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Panagaki T, Lozano-Montes L, Janickova L, Zuhra K, Szabo MP, Majtan T, Rainer G, Maréchal D, Herault Y, Szabo C. Overproduction of hydrogen sulfide, generated by cystathionine β-synthase, disrupts brain wave patterns and contributes to neurobehavioral dysfunction in a rat model of down syndrome. Redox Biol 2022; 51:102233. [PMID: 35042677 PMCID: PMC9039679 DOI: 10.1016/j.redox.2022.102233] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 12/26/2021] [Accepted: 01/10/2022] [Indexed: 12/23/2022] Open
Abstract
Using a novel rat model of Down syndrome (DS), the functional role of the cystathionine-β-synthase (CBS)/hydrogen sulfide (H2S) pathway was investigated on the pathogenesis of brain wave pattern alterations and neurobehavioral dysfunction. Increased expression of CBS and subsequent overproduction of H2S was observed in the brain of DS rats, with CBS primarily localizing to astrocytes and the vasculature. DS rats exhibited neurobehavioral defects, accompanied by a loss of gamma brain wave activity and a suppression of the expression of multiple pre- and postsynaptic proteins. Aminooxyacetate, a prototypical pharmacological inhibitor of CBS, increased the ability of the DS brain tissue to generate ATP in vitro and reversed the electrophysiological and neurobehavioral alterations in vivo. Thus, the CBS/H2S pathway contributes to the pathogenesis of neurological dysfunction in DS, most likely through dysregulation of cellular bioenergetics and gene expression.
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Affiliation(s)
- Theodora Panagaki
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Laura Lozano-Montes
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland; Visual Cognition Laboratory, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Lucia Janickova
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Karim Zuhra
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Marcell P Szabo
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Tomas Majtan
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Gregor Rainer
- Visual Cognition Laboratory, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Damien Maréchal
- Université de Strasbourg, CNRS, INSERM, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France
| | - Yann Herault
- Université de Strasbourg, CNRS, INSERM, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France
| | - Csaba Szabo
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland.
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Abstract
PURPOSE OF REVIEW Metabolism of sulfur amino acids (SAA) provides compounds important for many cellular functions. Inherited disorders of SAA metabolism are typically severe multisystemic diseases affecting brain, liver, connective tissue, or vasculature. The review summarizes the present therapeutic approaches and advances in identifying novel treatment targets, and provides an overview of new therapies. RECENT FINDINGS Current treatments of genetic disorders of SAA metabolism are primarily based on modulation of affected pathways by dietary measures and provision of lacking products or scavenging of toxic molecules. Recent studies identified additional therapeutic targets distant from the primary defects and explored ideas envisioning novel treatments, such as chaperone and gene therapy. Recombinant protein production and engineering resulted in development and clinical testing of enzyme therapies for cystathionine β-synthase deficiency, the most common inborn error of SAA metabolism. SUMMARY Complex regulation of pathways involved in SAA metabolism and cellular consequences of genetic defects in SAA metabolism are only partially understood. There is a pressing need to increase substantially our knowledge of the disease mechanisms to develop more effective therapies for patients suffering from these rare disorders.
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Affiliation(s)
- Viktor Kožich
- Department of Pediatrics and Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital, Czech Republic
| | - Tomas Majtan
- Section of Genetics and Metabolism, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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Park I, Johnson LK, Cox A, Branchford BR, Paola JD, Bublil EM, Majtan T. Hypermethioninemia Leads to Fatal Bleeding and Increased Mortality in a Transgenic I278T Mouse Model of Homocystinuria. Biomedicines 2020; 8:biomedicines8080244. [PMID: 32722248 PMCID: PMC7459533 DOI: 10.3390/biomedicines8080244] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/17/2020] [Accepted: 07/22/2020] [Indexed: 01/20/2023] Open
Abstract
Severely elevated plasma homocysteine and methionine lead to thromboembolic events and strokes in homocystinuric (HCU) patients. Mouse models of HCU failed to exhibit prothrombotic phenotype, presumably due to lack of hypermethioninemia. We evaluated the impact of hypermethioninemia together with hyperhomocysteinemia on murine HCU phenotype and compared the efficacy of the current and novel therapies for HCU. High methionine intake decreased survival of I278T mice, which died from intestinal bleeding with hepatic and pancreatic failure. I278T mice on normal or increased methionine intake developed endothelial dysfunction, but paradoxically demonstrated delayed occlusion in an induced arterial thrombosis model. RNA-seq analysis suggested that expression of coagulation factor XI (FXI) is downregulated in livers of I278T mice. Indeed, plasma concentrations of FXI were decreased in I278T mice on normal diet and further reduced by increased methionine intake. Dietary methionine restriction normalized the observed phenotype. Similarly, treatment with OT-58, a novel enzyme therapy for HCU, corrected the phenotype in I278T mice regardless of their dietary methionine intake. Hypermethioninemia does not contribute to prothrombotic phenotype in murine HCU. Downregulation of FXI may contribute to the lack of prothrombotic tendency in I278T mice. Methionine restriction or treatment with OT-58 corrects vascular disease in the I278T mouse model of HCU.
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Affiliation(s)
- Insun Park
- Section of Genetics & Metabolism, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA;
| | - Linda K. Johnson
- Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA;
| | - Allaura Cox
- Section of Hematology/Oncology, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA; (A.C.); (B.R.B.); (J.D.P.)
- University of Colorado Hemophilia and Thrombosis Center, Aurora, CO 80045, USA
| | - Brian R. Branchford
- Section of Hematology/Oncology, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA; (A.C.); (B.R.B.); (J.D.P.)
- University of Colorado Hemophilia and Thrombosis Center, Aurora, CO 80045, USA
| | - Jorge Di Paola
- Section of Hematology/Oncology, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA; (A.C.); (B.R.B.); (J.D.P.)
- University of Colorado Hemophilia and Thrombosis Center, Aurora, CO 80045, USA
| | | | - Tomas Majtan
- Section of Genetics & Metabolism, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA;
- Correspondence: ; Tel.: +1-303-724-3813
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Park I, Hůlková H, Krijt J, Kožich V, Bublil EM, Majtan T. Long-term uninterrupted enzyme replacement therapy prevents liver disease in murine model of severe homocystinuria. Hum Mutat 2020; 41:1662-1670. [PMID: 32623804 DOI: 10.1002/humu.24072] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/16/2020] [Accepted: 07/02/2020] [Indexed: 11/09/2022]
Abstract
Classical homocystinuria (HCU) is an inborn error of metabolism caused by loss of cystathionine β-synthase (CBS) activity with the concomitant buildup of homocysteine. In knockout (KO) mice, a mouse model of HCU, complete lack of CBS is neonatally lethal. Administration of OT-58, an enzyme therapy for HCU, during the first 5 weeks of life rescued KO mice survival by preventing liver disease. Here, we studied the impact of a long-term uninterrupted OT-58 treatment or its absence beyond the neonatal period on liver pathology and metabolism. Plasma and liver metabolites of KO mice on OT-58 treatment were substantially improved or normalized compared with those receiving vehicle. Increased plasma activities of alanine aminotransferase and aspartate aminotransferase of vehicle-injected KO mice suggested the progression of liver damage with age and lack of treatment. At 3 months of age, liver histology showed no signs of hepatopathy in both vehicle- and OT-58-treated KO mice. However, moderate to severe liver disease, characterized by steatosis, hepatocellular necroses, disorganized endoplasmic reticulum, and swollen mitochondria, developed in 6-month-old vehicle-injected KO mice. KO mice on OT-58 treatment remained asymptomatic and were indistinguishable from age-matched healthy controls. Long-term uninterrupted OT-58 treatment was essential to prevent severe liver disease in the KO mouse model of HCU.
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Affiliation(s)
- Insun Park
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Helena Hůlková
- Institute of Pathology, Charles University-First Faculty of Medicine and General University Hospital, Prague, Czech Republic.,Department of Pediatrics and Adolescent Medicine, Charles University-First Faculty of Medicine and General University Hospital, Prague, Czech Republic
| | - Jakub Krijt
- Department of Pediatrics and Adolescent Medicine, Charles University-First Faculty of Medicine and General University Hospital, Prague, Czech Republic
| | - Viktor Kožich
- Department of Pediatrics and Adolescent Medicine, Charles University-First Faculty of Medicine and General University Hospital, Prague, Czech Republic
| | | | - Tomas Majtan
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
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Bublil EM, Majtan T. Classical homocystinuria: From cystathionine beta-synthase deficiency to novel enzyme therapies. Biochimie 2020; 173:48-56. [DOI: 10.1016/j.biochi.2019.12.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 12/13/2019] [Indexed: 01/23/2023]
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Zuhra K, Augsburger F, Majtan T, Szabo C. Cystathionine-β-Synthase: Molecular Regulation and Pharmacological Inhibition. Biomolecules 2020; 10:E697. [PMID: 32365821 PMCID: PMC7277093 DOI: 10.3390/biom10050697] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 04/24/2020] [Accepted: 04/27/2020] [Indexed: 12/11/2022] Open
Abstract
Cystathionine-β-synthase (CBS), the first (and rate-limiting) enzyme in the transsulfuration pathway, is an important mammalian enzyme in health and disease. Its biochemical functions under physiological conditions include the metabolism of homocysteine (a cytotoxic molecule and cardiovascular risk factor) and the generation of hydrogen sulfide (H2S), a gaseous biological mediator with multiple regulatory roles in the vascular, nervous, and immune system. CBS is up-regulated in several diseases, including Down syndrome and many forms of cancer; in these conditions, the preclinical data indicate that inhibition or inactivation of CBS exerts beneficial effects. This article overviews the current information on the expression, tissue distribution, physiological roles, and biochemistry of CBS, followed by a comprehensive overview of direct and indirect approaches to inhibit the enzyme. Among the small-molecule CBS inhibitors, the review highlights the specificity and selectivity problems related to many of the commonly used "CBS inhibitors" (e.g., aminooxyacetic acid) and provides a comprehensive review of their pharmacological actions under physiological conditions and in various disease models.
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Affiliation(s)
- Karim Zuhra
- Chair of Pharmacology, Section of Medicine, University of Fribourg, 1702 Fribourg, Switzerland; (K.Z.); (F.A.)
| | - Fiona Augsburger
- Chair of Pharmacology, Section of Medicine, University of Fribourg, 1702 Fribourg, Switzerland; (K.Z.); (F.A.)
| | - Tomas Majtan
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA;
| | - Csaba Szabo
- Chair of Pharmacology, Section of Medicine, University of Fribourg, 1702 Fribourg, Switzerland; (K.Z.); (F.A.)
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Affiliation(s)
- Viktor Kožich
- Department of Pediatrics and Adolescent Medicine Charles University‐First Faculty of Medicine and General University Hospital Prague Czech Republic
| | - Tomas Majtan
- Department of Pediatrics, Section of Genetics and Metabolism University of Colorado Anschutz Medical Campus Aurora Colorado
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Majtan T, Park I, Cox A, Branchford BR, di Paola J, Bublil EM, Kraus JP. Behavior, body composition, and vascular phenotype of homocystinuric mice on methionine-restricted diet or enzyme replacement therapy. FASEB J 2019; 33:12477-12486. [PMID: 31450979 DOI: 10.1096/fj.201901203r] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Classic homocystinuria (HCU) is an inherited disorder characterized by elevated homocysteine (Hcy) in plasma and tissues resulting from cystathionine β-synthase (CBS) deficiency. There is no cure, and patients are predominantly managed by methionine-restricted diet (MRD) to limit the production of Hcy. In this study, we used the I278T mouse model of HCU to evaluate the long-term impact of a novel enzyme replacement therapy [truncated human CBS C15S mutant modified with linear 20-kDa N-hydroxysuccinimide ester polyethylene glycol (OT-58)] on clinical end points relevant to human patients with HCU. In addition, we compared its efficacy on a background of either MRD or normal methionine intake [regular diet (REG)] to that of MRD alone. We found that, compared with untreated I278T mice, OT-58 treatment of I278T mice fed with the REG diet resulted in a 90% decrease in plasma Hcy concentrations and correction of learning/cognition, endothelial dysfunction, hemostasis, bone mineralization, and body composition. On background of the MRD, OT-58 performed equally well with plasma Hcy entirely normalized. The MRD alone decreased plasma Hcy by 67% and corrected the HCU phenotype in I278T mice. However, the MRD increased anxiety and reduced bone mineral content in both I278T mice and wild-type controls. This study shows that OT-58 is a highly efficacious novel treatment for HCU on the background of either normal or restricted methionine intake.-Majtan, T., Park, I., Cox, A., Branchford, B. R., di Paola, J., Bublil, E. M., Kraus, J. P. Behavior, body composition, and vascular phenotype of homocystinuric mice on methionine-restricted diet or enzyme replacement therapy.
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Affiliation(s)
- Tomas Majtan
- Section of Genetics, Department of Pediatrics, School of Medicine, University of Colorado, Aurora, Colorado, USA
| | - Insun Park
- Section of Genetics, Department of Pediatrics, School of Medicine, University of Colorado, Aurora, Colorado, USA
| | - Allaura Cox
- Section of Hematology/Oncology, Department of Pediatrics, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado, USA.,Hemophilia and Thrombosis Center, University of Colorado, Aurora, Colorado, USA
| | - Brian R Branchford
- Section of Hematology/Oncology, Department of Pediatrics, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado, USA.,Hemophilia and Thrombosis Center, University of Colorado, Aurora, Colorado, USA
| | - Jorge di Paola
- Section of Hematology/Oncology, Department of Pediatrics, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado, USA.,Hemophilia and Thrombosis Center, University of Colorado, Aurora, Colorado, USA
| | - Erez M Bublil
- Orphan Technologies Limited, Rapperswil, Switzerland
| | - Jan P Kraus
- Section of Genetics, Department of Pediatrics, School of Medicine, University of Colorado, Aurora, Colorado, USA
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Majtan T, Bublil EM, Park I, Arning E, Bottiglieri T, Glavin F, Kraus JP. Pharmacokinetics and pharmacodynamics of PEGylated truncated human cystathionine beta-synthase for treatment of homocystinuria. Life Sci 2018. [PMID: 29526799 DOI: 10.1016/j.lfs.2018.03.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
AIMS PEGylated human truncated cystathionine beta-synthase, lacking the C-terminal regulatory domain (PEG-CBS), is a promising preclinical candidate for enzyme replacement therapy in homocystinuria (HCU). It was designed to function as a metabolic sink to decrease the severely elevated plasma and tissue homocysteine concentrations. In this communication, we evaluated pharmacokinetics (PK), pharmacodynamics (PD) and sub-chronic toxicity of PEG-CBS in homocystinuric mice, wild type rats and monkeys to estimate the minimum human efficacious dose for clinical trials. MAIN METHODS Animal models received single or multiple doses of PEG-CBS. Activity of PEG-CBS and sulfur amino acid metabolites were determined in plasma and used to determine PK and PD. KEY FINDINGS The plasma half-lives of PEG-CBS after a single subcutaneous (SC) injection were approximately 20, 44 and 73 h in mouse, rat and monkey, respectively. The SC administration of PEG-CBS resulted in a significant improvement or full correction of metabolic imbalance in both blood and tissues of homocystinuric mice. The PD of PEG-CBS in mouse was dose-dependent, but less than dose-proportional, with the maximal efficacy achieved at 8 mg/kg. PEG-CBS was well-tolerated in mice and monkeys, but resulted in dose-dependent minimal-to-moderate inflammation at the injection sites and vacuolated macrophages in rats. Allometric scaling of animal data was linear and the estimated human efficacious dose was determined as 0.66 mg/kg administered once a week. SIGNIFICANCE These results provide critical preclinical data for the design of first-in-human PEG-CBS clinical trial.
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Affiliation(s)
- Tomas Majtan
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA.
| | - Erez M Bublil
- Orphan Technologies Ltd., Rapperswill CH-8640, Switzerland
| | - Insun Park
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Erland Arning
- Institute of Metabolic Disease, Baylor Scott & White Research Institute, Dallas, TX 75226, USA
| | - Teodoro Bottiglieri
- Institute of Metabolic Disease, Baylor Scott & White Research Institute, Dallas, TX 75226, USA
| | - Frank Glavin
- Orphan Technologies Ltd., Rapperswill CH-8640, Switzerland
| | - Jan P Kraus
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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15
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Majtan T, Krijt J, Sokolová J, Křížková M, Ralat MA, Kent J, Gregory JF, Kožich V, Kraus JP. Biogenesis of Hydrogen Sulfide and Thioethers by Cystathionine Beta-Synthase. Antioxid Redox Signal 2018; 28:311-323. [PMID: 28874062 DOI: 10.1089/ars.2017.7009] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
AIMS The transsulfuration pathway enzymes cystathionine beta-synthase (CBS) and cystathionine gamma-lyase are thought to be the major source of hydrogen sulfide (H2S). In this study, we assessed the role of CBS in H2S biogenesis. RESULTS We show that despite discouraging enzyme kinetics of alternative H2S-producing reactions utilizing cysteine compared with the canonical condensation of serine and homocysteine, our simulations of substrate competitions at biologically relevant conditions suggest that cysteine is able to partially compete with serine on CBS, thus leading to generation of appreciable amounts of H2S. The leading H2S-producing reaction is condensation of cysteine with homocysteine, while cysteine desulfuration plays a dominant role when cysteine is more abundant than serine and homocysteine is limited. We found that the serine-to-cysteine ratio is the main determinant of CBS H2S productivity. Abundance of cysteine over serine, for example, in plasma, allowed for up to 43% of CBS activity being responsible for H2S production, while excess of serine typical for intracellular levels effectively limited such activity to less than 1.5%. CBS also produced lanthionine from serine and cysteine and a third of lanthionine coming from condensation of two cysteines contributed to the H2S pool. INNOVATION Our study characterizes the H2S-producing potential of CBS under biologically relevant conditions and highlights the serine-to-cysteine ratio as the main determinant of H2S production by CBS in vivo. CONCLUSION Our data clarify the function of CBS in H2S biogenesis and the role of thioethers as surrogate H2S markers. Antioxid. Redox Signal. 28, 311-323.
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Affiliation(s)
- Tomas Majtan
- 1 Department of Pediatrics, University of Colorado , School of Medicine, Aurora, Colorado
| | - Jakub Krijt
- 2 Department of Pediatrics and Adolescent Medicine, Charles University-First Faculty of Medicine and General University Hospital in Prague , Prague, Czech Republic
| | - Jitka Sokolová
- 2 Department of Pediatrics and Adolescent Medicine, Charles University-First Faculty of Medicine and General University Hospital in Prague , Prague, Czech Republic
| | - Michaela Křížková
- 2 Department of Pediatrics and Adolescent Medicine, Charles University-First Faculty of Medicine and General University Hospital in Prague , Prague, Czech Republic
| | - Maria A Ralat
- 3 Department of Food Science and Human Nutrition, Institute of Food and Agricultural Sciences, University of Florida , Gainesville, Florida
| | - Jana Kent
- 1 Department of Pediatrics, University of Colorado , School of Medicine, Aurora, Colorado
| | - Jesse F Gregory
- 3 Department of Food Science and Human Nutrition, Institute of Food and Agricultural Sciences, University of Florida , Gainesville, Florida
| | - Viktor Kožich
- 2 Department of Pediatrics and Adolescent Medicine, Charles University-First Faculty of Medicine and General University Hospital in Prague , Prague, Czech Republic
| | - Jan P Kraus
- 1 Department of Pediatrics, University of Colorado , School of Medicine, Aurora, Colorado
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16
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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
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Giménez-Mascarell P, Majtan T, Oyenarte I, Ereño-Orbea J, Majtan J, Klaudiny J, Kraus JP, Martínez-Cruz LA. Crystal structure of cystathionine β-synthase from honeybee Apis mellifera. J Struct Biol 2017; 202:82-93. [PMID: 29275181 DOI: 10.1016/j.jsb.2017.12.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/28/2017] [Accepted: 12/19/2017] [Indexed: 11/26/2022]
Abstract
Cystathionine β-synthase (CBS), the key enzyme in the transsulfuration pathway, links methionine metabolism to the biosynthesis of cellular redox controlling molecules. CBS catalyzes the pyridoxal-5'-phosphate-dependent condensation of serine and homocysteine to form cystathionine, which is subsequently converted into cysteine. Besides maintaining cellular sulfur amino acid homeostasis, CBS also catalyzes multiple hydrogen sulfide-generating reactions using cysteine and homocysteine as substrates. In mammals, CBS is activated by S-adenosylmethionine (AdoMet), where it can adopt two different conformations (basal and activated), but exists as a unique highly active species in fruit fly Drosophila melanogaster. Here we present the crystal structure of CBS from honeybey Apis mellifera, which shows a constitutively active dimeric species and let explain why the enzyme is not allosterically regulated by AdoMet. In addition, comparison of available CBS structures unveils a substrate-induced closure of the catalytic cavity, which in humans is affected by the AdoMet-dependent regulation and likely impaired by the homocystinuria causing mutation T191M.
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Affiliation(s)
- Paula Giménez-Mascarell
- Structural Biology Unit, Center for Cooperative Research in Biosciences (CIC Biogune), Technology Park of Bizkaia, 48160 Derio, Bizkaia, Spain
| | - Tomas Majtan
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, CO 80045, USA
| | - Iker Oyenarte
- Structural Biology Unit, Center for Cooperative Research in Biosciences (CIC Biogune), Technology Park of Bizkaia, 48160 Derio, Bizkaia, Spain
| | - June Ereño-Orbea
- Structural Biology Unit, Center for Cooperative Research in Biosciences (CIC Biogune), Technology Park of Bizkaia, 48160 Derio, Bizkaia, Spain
| | - Juraj Majtan
- Laboratory of Apidology and Apitherapy, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava 84551, Slovakia
| | - Jaroslav Klaudiny
- Department of Glycobiology, Institute of Chemistry, Slovak Academy of Sciences, Bratislava 84538, Slovakia
| | - Jan P Kraus
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, CO 80045, USA
| | - Luis Alfonso Martínez-Cruz
- Structural Biology Unit, Center for Cooperative Research in Biosciences (CIC Biogune), Technology Park of Bizkaia, 48160 Derio, Bizkaia, Spain.
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18
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Majtan T, Jones W, Krijt J, Park I, Kruger WD, Kožich V, Bassnett S, Bublil EM, Kraus JP. Enzyme Replacement Therapy Ameliorates Multiple Symptoms of Murine Homocystinuria. Mol Ther 2017; 26:834-844. [PMID: 29398487 DOI: 10.1016/j.ymthe.2017.12.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 12/12/2017] [Accepted: 12/14/2017] [Indexed: 01/21/2023] Open
Abstract
Classical homocystinuria (HCU) is the most common inherited disorder of sulfur amino acid metabolism caused by deficiency in cystathionine beta-synthase (CBS) activity and characterized by severe elevation of homocysteine in blood and tissues. Treatment with dietary methionine restriction is not optimal, and poor compliance leads to serious complications. We developed an enzyme replacement therapy (ERT) and studied its efficacy in a severe form of HCU in mouse (the I278T model). Treatment was initiated before or after the onset of clinical symptoms in an effort to prevent or reverse the phenotype. ERT substantially reduced and sustained plasma homocysteine concentration at around 100 μM and normalized plasma cysteine for up to 9 months of treatment. Biochemical balance was also restored in the liver, kidney, and brain. Furthermore, ERT corrected liver glucose and lipid metabolism. The treatment prevented or reversed facial alopecia, fragile and lean phenotype, and low bone mass. In addition, structurally defective ciliary zonules in the eyes of I278T mice contained low density and/or broken fibers, while administration of ERT from birth partially rescued the ocular phenotype. In conclusion, ERT maintained an improved metabolic pattern and ameliorated many of the clinical complications in the I278T mouse model of HCU.
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Affiliation(s)
- Tomas Majtan
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA.
| | - Wendell Jones
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jakub Krijt
- Department of Pediatrics and Adolescent Medicine, Charles University-First Faculty of Medicine and General University Hospital in Prague, Prague 12808, Czech Republic
| | - Insun Park
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Warren D Kruger
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Viktor Kožich
- Department of Pediatrics and Adolescent Medicine, Charles University-First Faculty of Medicine and General University Hospital in Prague, Prague 12808, Czech Republic
| | - Steven Bassnett
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Erez M Bublil
- Orphan Technologies, Ltd., Rapperswil 8640, Switzerland
| | - Jan P Kraus
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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19
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Majtan T, Park I, Bublil EM, Kraus JP. Enzyme replacement therapy prevents loss of bone and fat mass in murine homocystinuria. Hum Mutat 2017; 39:210-218. [PMID: 29044829 DOI: 10.1002/humu.23360] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 10/03/2017] [Accepted: 10/11/2017] [Indexed: 01/04/2023]
Abstract
Skeletal and connective tissue defects are the most striking symptoms in patients suffering from classical homocystinuria (HCU). Here, we determined body composition and bone mass in three mouse models of HCU and assessed whether a long-term administration of enzyme replacement therapy (ERT) corrected the phenotype. The mouse models of HCU were analyzed using dual-energy X-ray absorptiometry and the data were complemented by plasma biochemical profiles. Both the mouse model lacking CBS (KO) and the one expressing human CBS mutant transgene on a mouse CBS null background (I278T) showed marked bone loss and decreased weight mostly due to a lower fat content compared with negative controls. In contrast, the HO mouse expressing the human CBS WT transgene on a mouse CBS null background showed no such phenotype despite similar plasma biochemical profile to the KO and I278T mice. More importantly, administration of ERT rescued bone mass and changes in body composition in the KO mice treated since birth and reversed bone loss and improved fat content in the I278T mice injected after the development of clinical symptoms. Our study suggests that ERT for HCU may represent an effective way of preventing the skeletal problems in patients without a restricted dietary regime.
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Affiliation(s)
- Tomas Majtan
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado
| | - Insun Park
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado
| | | | - Jan P Kraus
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado
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20
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Majtan T, Hůlková H, Park I, Krijt J, Kožich V, Bublil EM, Kraus JP. Enzyme replacement prevents neonatal death, liver damage, and osteoporosis in murine homocystinuria. FASEB J 2017; 31:5495-5506. [PMID: 28821635 DOI: 10.1096/fj.201700565r] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 07/31/2017] [Indexed: 11/11/2022]
Abstract
Classical homocystinuria (HCU) is an inborn error of sulfur amino acid metabolism caused by deficient activity of cystathionine β-synthase (CBS), resulting in an accumulation of homocysteine and a concomitant decrease of cystathionine and cysteine in blood and tissues. In mice, the complete lack of CBS is neonatally lethal. In this study, newborn CBS-knockout (KO) mice were treated with recombinant polyethyleneglycolylated human truncated CBS (PEG-CBS). Full survival of the treated KO mice, along with a positive impact on metabolite levels in plasma, liver, brain, and kidneys, was observed. The PEG-CBS treatment prevented an otherwise fatal liver disease characterized by steatosis, death of hepatocytes, and ultrastructural abnormalities of endoplasmic reticulum and mitochondria. Furthermore, treatment of the KO mice for 5 mo maintained the plasma metabolite balance and completely prevented osteoporosis and changes in body composition that characterize both the KO model and human patients. These findings argue that early treatment of patients with HCU with PEG-CBS may prevent clinical symptoms of the disease possibly without the need of dietary protein restriction.-Majtan, T., Hůlková, H., Park, I., Krijt, J., Kožich, V., Bublil, E. M., Kraus, J. P. Enzyme replacement prevents neonatal death, liver damage, and osteoporosis in murine homocystinuria.
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Affiliation(s)
- Tomas Majtan
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, USA;
| | - Helena Hůlková
- Institute of Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital, Prague, Czech Republic.,Institute of Pathology, Charles University-First Faculty of Medicine and General University Hospital, Prague, Czech Republic; and
| | - Insun Park
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Jakub Krijt
- Institute of Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital, Prague, Czech Republic
| | - Viktor Kožich
- Institute of Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital, Prague, Czech Republic
| | - Erez M Bublil
- Orphan Technologies Limited, Rapperswil, Switzerland
| | - Jan P Kraus
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, USA;
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21
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Majtan T, Park I, Carrillo RS, Bublil EM, Kraus JP. Engineering and Characterization of an Enzyme Replacement Therapy for Classical Homocystinuria. Biomacromolecules 2017; 18:1747-1761. [DOI: 10.1021/acs.biomac.7b00154] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Tomas Majtan
- Department
of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado 80045, United States
| | - Insun Park
- Department
of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado 80045, United States
| | - Richard S. Carrillo
- Department
of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado 80045, United States
| | - Erez M. Bublil
- Orphan
Technologies Ltd., Rapperswil, CH-8640, Switzerland
| | - Jan P. Kraus
- Department
of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado 80045, United States
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22
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Pey AL, Martínez-Cruz LA, Kraus JP, Majtan T. Oligomeric status of human cystathionine beta-synthase modulates AdoMet binding. FEBS Lett 2016; 590:4461-4471. [DOI: 10.1002/1873-3468.12488] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 10/26/2016] [Accepted: 11/06/2016] [Indexed: 01/26/2023]
Affiliation(s)
- Angel L. Pey
- Department of Physical Chemistry; Faculty of Sciences; University of Granada; Spain
| | | | - Jan P. Kraus
- Department of Pediatrics; University of Colorado Denver; Aurora CO USA
| | - Tomas Majtan
- Department of Pediatrics; University of Colorado Denver; Aurora CO USA
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23
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Majtan T, L. Pey A, Ereño-Orbea J, Alfonso Martínez-Cruz L, P. Kraus J. Targeting Cystathionine Beta-Synthase Misfolding in Homocystinuria by Small Ligands: State of the Art and Future Directions. Curr Drug Targets 2016; 17:1455-70. [DOI: 10.2174/1389450117666160302094910] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 09/10/2015] [Accepted: 02/29/2016] [Indexed: 11/22/2022]
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24
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Bublil EM, Majtan T, Park I, Carrillo RS, Hůlková H, Krijt J, Kožich V, Kraus JP. Enzyme replacement with PEGylated cystathionine β-synthase ameliorates homocystinuria in murine model. J Clin Invest 2016; 126:2372-84. [PMID: 27183385 DOI: 10.1172/jci85396] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 03/22/2016] [Indexed: 01/16/2023] Open
Abstract
Homocystinuria, which typically results from cystathionine β-synthase (CBS) deficiency, is the most common defect of sulfur amino acid metabolism. CBS condenses homocysteine and serine to cystathionine that is then converted to cysteine. Individuals with homocystinuria have markedly elevated plasma levels of homocysteine and methionine and reduced concentrations of cystathionine and cysteine. Clinical disease manifestations include thromboembolism and neuropsychiatric, ocular, and skeletal complications. Here, we have shown that administration of PEGylated CBS into the circulation of homocystinuria model mice alters the extra- and intracellular equilibrium of sulfur amino acids, resulting in a decrease of approximately 75% in plasma total homocysteine (tHcy) and normalization of cysteine concentrations. Moreover, the decrease in homocysteine and the normalization of cysteine in PEGylated CBS-treated model mice were accompanied by improvement of histopathological liver symptoms and increased survival. Together, these data suggest that CBS enzyme replacement therapy (ERT) is a promising approach for the treatment of homocystinuria and that ERT for metabolic diseases may not necessitate introduction of the deficient enzyme into its natural intracellular compartment.
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Majtan T, Bublil E, Park I, Carrillo R, Ereño-Orbea J, Martínez-Cruz LA, Hůlková H, Krijt J, Kožich V, Kruger W, Kraus JP. CBS update: Structure, CBS replacement therapy, and H2S production. Nitric Oxide 2015. [DOI: 10.1016/j.niox.2015.02.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Thorson MK, Van Wagoner RM, Harper MK, Ireland CM, Majtan T, Kraus JP, Barrios AM. Marine natural products as inhibitors of cystathionine beta-synthase activity. Bioorg Med Chem Lett 2015; 25:1064-6. [PMID: 25666819 DOI: 10.1016/j.bmcl.2015.01.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 01/05/2015] [Accepted: 01/07/2015] [Indexed: 10/24/2022]
Abstract
A library consisting of characterized marine natural products as well as synthetic derivatives was screened for compounds capable of inhibiting the production of hydrogen sulfide (H2S) by cystathionine beta-synthase (CBS). Eight hits were validated and shown to inhibit CBS activity with IC50 values ranging from 83 to 187μM. The majority of hits came from a series of synthetic polyandrocarpamine derivatives. In addition, a modified fluorogenic probe for H2S detection with improved solubility in aqueous solutions is reported.
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Affiliation(s)
- Megan K Thorson
- Department of Medicinal Chemistry, University of Utah, 30 South 2000 East, Salt Lake City, UT 84112, USA
| | - Ryan M Van Wagoner
- Department of Medicinal Chemistry, University of Utah, 30 South 2000 East, Salt Lake City, UT 84112, USA
| | - Mary Kay Harper
- Department of Medicinal Chemistry, University of Utah, 30 South 2000 East, Salt Lake City, UT 84112, USA
| | - Chris M Ireland
- Department of Medicinal Chemistry, University of Utah, 30 South 2000 East, Salt Lake City, UT 84112, USA
| | - Tomas Majtan
- Department of Pediatrics, University of Colorado, Aurora, CO 80045, USA
| | - Jan P Kraus
- Department of Pediatrics, University of Colorado, Aurora, CO 80045, USA
| | - Amy M Barrios
- Department of Medicinal Chemistry, University of Utah, 30 South 2000 East, Salt Lake City, UT 84112, USA.
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Majtan T, Pey AL, Fernández R, Fernández JA, Martínez-Cruz LA, Kraus JP. Domain organization, catalysis and regulation of eukaryotic cystathionine beta-synthases. PLoS One 2014; 9:e105290. [PMID: 25122507 PMCID: PMC4133348 DOI: 10.1371/journal.pone.0105290] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 07/23/2014] [Indexed: 01/01/2023] Open
Abstract
Cystathionine beta-synthase (CBS) is a key regulator of sulfur amino acid metabolism diverting homocysteine, a toxic intermediate of the methionine cycle, via the transsulfuration pathway to the biosynthesis of cysteine. Although the pathway itself is well conserved among eukaryotes, properties of eukaryotic CBS enzymes vary greatly. Here we present a side-by-side biochemical and biophysical comparison of human (hCBS), fruit fly (dCBS) and yeast (yCBS) enzymes. Preparation and characterization of the full-length and truncated enzymes, lacking the regulatory domains, suggested that eukaryotic CBS exists in one of at least two significantly different conformations impacting the enzyme’s catalytic activity, oligomeric status and regulation. Truncation of hCBS and yCBS, but not dCBS, resulted in enzyme activation and formation of dimers compared to native tetramers. The dCBS and yCBS are not regulated by the allosteric activator of hCBS, S-adenosylmethionine (AdoMet); however, they have significantly higher specific activities in the canonical as well as alternative reactions compared to hCBS. Unlike yCBS, the heme-containing dCBS and hCBS showed increased thermal stability and retention of the enzyme’s catalytic activity. The mass-spectrometry analysis and isothermal titration calorimetry showed clear presence and binding of AdoMet to yCBS and hCBS, but not dCBS. However, the role of AdoMet binding to yCBS remains unclear, unlike its role in hCBS. This study provides valuable information for understanding the complexity of the domain organization, catalytic specificity and regulation among eukaryotic CBS enzymes.
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Affiliation(s)
- Tomas Majtan
- Department of Pediatrics, University of Colorado, School of Medicine, Aurora, Colorado, United States of America
| | - Angel L. Pey
- Department of Physical Chemistry, Faculty of Sciences, University of Granada, Granada, Spain
| | - Roberto Fernández
- Department of Physical Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - José A. Fernández
- Department of Physical Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | | | - Jan P. Kraus
- Department of Pediatrics, University of Colorado, School of Medicine, Aurora, Colorado, United States of America
- * E-mail:
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Pey AL, Majtan T, Kraus JP. The role of surface electrostatics on the stability, function and regulation of human cystathionine β-synthase, a complex multidomain and oligomeric protein. Biochim Biophys Acta 2014; 1844:1453-62. [PMID: 24780582 DOI: 10.1016/j.bbapap.2014.04.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 04/06/2014] [Accepted: 04/21/2014] [Indexed: 11/25/2022]
Abstract
Human cystathionine β-synthase (hCBS) is a key enzyme of sulfur amino acid metabolism, controlling the commitment of homocysteine to the transsulfuration pathway and antioxidant defense. Mutations in hCBS cause inherited homocystinuria (HCU), a rare inborn error of metabolism characterized by accumulation of toxic homocysteine in blood and urine. hCBS is a complex multidomain and oligomeric protein whose activity and stability are independently regulated by the binding of S-adenosyl-methionine (SAM) to two different types of sites at its C-terminal regulatory domain. Here we study the role of surface electrostatics on the complex regulation and stability of hCBS using biophysical and biochemical procedures. We show that the kinetic stability of the catalytic and regulatory domains is significantly affected by the modulation of surface electrostatics through noticeable structural and energetic changes along their denaturation pathways. We also show that surface electrostatics strongly affect SAM binding properties to those sites responsible for either enzyme activation or kinetic stabilization. Our results provide new insight into the regulation of hCBS activity and stability in vivo with implications for understanding HCU as a conformational disease. We also lend experimental support to the role of electrostatic interactions in the recently proposed binding modes of SAM leading to hCBS activation and kinetic stabilization.
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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.
| | - Tomas Majtan
- Department of Pediatrics, University of Colorado, School of Medicine, Aurora, CO 80045, USA
| | - Jan P Kraus
- Department of Pediatrics, University of Colorado, School of Medicine, Aurora, CO 80045, USA
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29
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Ereño-Orbea J, Majtan T, Oyenarte I, Kraus JP, Martínez-Cruz LA. Purification, crystallization and preliminary crystallographic analysis of the catalytic core of cystathionine β-synthase from Saccharomyces cerevisiae. Acta Crystallogr F Struct Biol Commun 2014; 70:320-5. [PMID: 24598918 DOI: 10.1107/s2053230x14001502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Accepted: 01/21/2014] [Indexed: 11/10/2022]
Abstract
Cystathionine β-synthase (CBS; EC 4.2.1.22) catalyzes the condensation of homocysteine and serine to form cystathionine, with the release of water. In humans, deficiency in CBS activity is the most common cause of hyperhomocysteinaemia and homocystinuria. More than 160 pathogenic mutations in the human CBS gene have been described to date. Here, the purification and preliminary crystallographic analysis of the catalytic core of CBS from Saccharomyces cerevisiae (ScCBS) is described which, in contrast to other eukaryotic CBSs, lacks the N-terminal haem-binding domain and is considered to be a useful model for investigation of the pyridoxal-5'-phosphate-mediated reactions of human CBS (hCBS). The purified protein yielded two different crystal forms belonging to space groups P41212 and P212121, with unit-cell parameters a = b = 72.390, c = 386.794 Å and a = 58.156, b = 89.988, c = 121.687 Å, respectively. Diffraction data were collected to 2.7 and 3.1 Å resolution, respectively, using synchrotron radiation. Preliminary analysis of the X-ray data suggests the presence of ScCBS homodimers in both types of crystals.
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Affiliation(s)
- June Ereño-Orbea
- Structural Biology Unit, CIC bioGUNE, Parque Tecnológico de Bizkaia, Edificio 800, 48160 Derio, Bizkaia , Spain
| | - Tomas Majtan
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Iker Oyenarte
- Structural Biology Unit, CIC bioGUNE, Parque Tecnológico de Bizkaia, Edificio 800, 48160 Derio, Bizkaia , Spain
| | - Jan P Kraus
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Luis Alfonso Martínez-Cruz
- Structural Biology Unit, CIC bioGUNE, Parque Tecnológico de Bizkaia, Edificio 800, 48160 Derio, Bizkaia , Spain
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Thorson MK, Majtan T, Kraus JP, Barrios AM. Identification of Cystathionine β-Synthase Inhibitors Using a Hydrogen Sulfide Selective Probe. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201300841] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Thorson MK, Majtan T, Kraus JP, Barrios AM. Identification of Cystathionine β-Synthase Inhibitors Using a Hydrogen Sulfide Selective Probe. Angew Chem Int Ed Engl 2013; 52:4641-4. [DOI: 10.1002/anie.201300841] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Indexed: 12/31/2022]
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Su Y, Majtan T, Freeman KM, Linck R, Ponter S, Kraus JP, Burstyn JN. Comparative study of enzyme activity and heme reactivity in Drosophila melanogaster and Homo sapiens cystathionine β-synthases. Biochemistry 2013; 52:741-51. [PMID: 23002992 PMCID: PMC3751582 DOI: 10.1021/bi300615c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cystathionine β-synthase (CBS) is the first and rate-limiting enzyme in the transsulfuration pathway, which is critical for the synthesis of cysteine from methionine in eukaryotes. CBS uses coenzyme pyridoxal 5'-phosphate (PLP) for catalysis, and S-adenosylmethionine regulates the activity of human CBS, but not yeast CBS. Human and fruit fly CBS contain heme; however, the role for heme is not clear. This paper reports biochemical and spectroscopic characterization of CBS from fruit fly Drosophila melanogaster (DmCBS) and the CO/NO gas binding reactions of DmCBS and human CBS. Like CBS enzymes from lower organisms (e.g., yeast), DmCBS is intrinsically highly active and is not regulated by AdoMet. The DmCBS heme coordination environment, the reactivity, and the accompanying effects on enzyme activity are similar to those of human CBS. The DmCBS heme bears histidine and cysteine axial ligands, and the enzyme becomes inactive when the cysteine ligand is replaced. The Fe(II) heme in DmCBS is less stable than that in human CBS, undergoing more facile reoxidation and ligand exchange. In both CBS proteins, the overall stability of the protein is correlated with the heme oxidation state. Human and DmCBS Fe(II) hemes react relatively slowly with CO and NO, and the rate of the CO binding reaction is faster at low pH than at high pH. Together, the results suggest that heme incorporation and AdoMet regulation in CBS are not correlated, possibly providing two independent means for regulating the enzyme.
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Affiliation(s)
- Yang Su
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin, 53706 USA
| | - Tomas Majtan
- Department of Pediatrics, University of Colorado, Denver, Aurora, Colorado 80045
- Department of Genomics & Biotechnology, Institute of Molecular Biology SAS, Dubravska cesta 21, Bratislava, 84551, Slovakia
| | - Katherine M. Freeman
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin, 53706 USA
| | - Rachel Linck
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin, 53706 USA
| | - Sarah Ponter
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin, 53706 USA
| | - Jan P. Kraus
- Department of Pediatrics, University of Colorado, Denver, Aurora, Colorado 80045
| | - Judith N. Burstyn
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin, 53706 USA
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Oyenarte I, Majtan T, Ereño J, Corral-Rodríguez MA, Kraus JP, Martínez-Cruz LA. Purification, crystallization and preliminary crystallographic analysis of human cystathionine β-synthase. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:1318-22. [PMID: 23143240 PMCID: PMC3515372 DOI: 10.1107/s1744309112037219] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 08/29/2012] [Indexed: 06/01/2023]
Abstract
Human cystathionine β-synthase (CBS) is a pyridoxal-5'-phosphate-dependent hemeprotein, whose catalytic activity is regulated by S-adenosylmethionine. CBS catalyzes the β-replacement reaction of homocysteine (Hcy) with serine to yield cystathionine. CBS is a key regulator of plasma levels of the thrombogenic Hcy and deficiency in CBS is the single most common cause of homocystinuria, an inherited metabolic disorder of sulfur amino acids. The properties of CBS enzymes, such as domain organization, oligomerization degree or regulatory mechanisms, are not conserved across the eukaryotes. The current body of knowledge is insufficient to understand these differences and their impact on CBS function and physiology. To overcome this deficiency, we have addressed the crystallization and preliminary crystallographic analysis of a protein construct (hCBS516-525) that contains the full-length CBS from Homo sapiens (hCBS) and just lacks amino-acid residues 516-525, which are located in a disordered loop. The human enzyme yielded crystals belonging to space group I222, with unit-cell parameters a=124.98, b=136.33, c=169.83 Å and diffracting X-rays to a resolution of 3.0 Å. The crystal structure appears to contain two molecules in the asymmetric unit which presumably correspond to a dimeric form of the enzyme.
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Affiliation(s)
- Iker Oyenarte
- Structural Biology Unit, CIC bioGUNE, Parque Tecnológico de Bizkaia, Edificio 800, Derio, Bizkaia 48160, Spain
| | - Tomas Majtan
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - June Ereño
- Structural Biology Unit, CIC bioGUNE, Parque Tecnológico de Bizkaia, Edificio 800, Derio, Bizkaia 48160, Spain
| | | | - Jan P. Kraus
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Luis Alfonso Martínez-Cruz
- Structural Biology Unit, CIC bioGUNE, Parque Tecnológico de Bizkaia, Edificio 800, Derio, Bizkaia 48160, Spain
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Oyenarte I, Majtan T, Ereño J, Corral-Rodríguez MA, Klaudiny J, Majtan J, Kraus JP, Martínez-Cruz LA. Purification, crystallization and preliminary crystallographic analysis of the full-length cystathionine β-synthase from Apis mellifera. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:1323-8. [PMID: 23143241 PMCID: PMC3515373 DOI: 10.1107/s1744309112038638] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 09/08/2012] [Indexed: 11/10/2022]
Abstract
Cystathionine β-synthase (CBS) is a pyridoxal-5'-phosphate-dependent enzyme that catalyzes the first step of the transsulfuration pathway, namely the condensation of serine with homocysteine to form cystathionine. Mutations in the CBS gene are the single most common cause of hereditary homocystinuria, a multisystemic disease affecting to various extents the vasculature, connective tissues and central nervous system. At present, the crystal structure of CBS from Drosophila melanogaster is the only available structure of the full-length enzyme. Here we describe a cloning, overexpression, purification and preliminary crystallographic analysis of a full-length CBS from Apis mellifera (AmCBS) which maintains 51 and 46% sequence identity with its Drosophila and human homologs, respectively. The AmCBS yielded crystals belonging to space group P2(1)2(1)2(1), with unit-cell parameters a=85.90, b=95.87, c=180.33 Å. Diffraction data were collected to a resolution of 3.0 Å. The crystal structure contained two molecules in the asymmetric unit which presumably correspond to the dimeric species observed in solution.
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Affiliation(s)
- Iker Oyenarte
- Structural Biology Unit, CIC bioGUNE, Parque Tecnológico de Bizkaia, Edificio 800, Derio, Bizkaia 48160, Spain
| | - Tomas Majtan
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - June Ereño
- Structural Biology Unit, CIC bioGUNE, Parque Tecnológico de Bizkaia, Edificio 800, Derio, Bizkaia 48160, Spain
| | | | - Jaroslav Klaudiny
- Institute of Zoology, Slovak Academy of Sciences, Dubravska cesta 9, Bratislava, 845 06, Slovakia
| | - Juraj Majtan
- Institute of Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, Bratislava, 845 38, Slovakia
| | - Jan P. Kraus
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Luis Alfonso Martínez-Cruz
- Structural Biology Unit, CIC bioGUNE, Parque Tecnológico de Bizkaia, Edificio 800, Derio, Bizkaia 48160, Spain
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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Affiliation(s)
- Aaron T Smith
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
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Hnı́zda A, Majtan T, Liu L, Pey AL, Carpenter JF, Kodı́ček M, Kožich V, Kraus JP. Correction to Conformational Properties of Nine Purified Cystathionine β-Synthase Mutants. Biochemistry 2012; 51:5540. [PMID: 22734603 DOI: 10.1021/bi300812f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hnízda A, Majtan T, Liu L, Pey AL, Carpenter JF, Kodíček M, Kožich V, Kraus JP. Conformational properties of nine purified cystathionine β-synthase mutants. Biochemistry 2012; 51:4755-63. [PMID: 22612060 PMCID: PMC3384745 DOI: 10.1021/bi300435e] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein misfolding due to missense mutations is a common pathogenic mechanism in cystathionine β-synthase (CBS) deficiency. In our previous studies, we successfully expressed, purified, and characterized nine CBS mutant enzymes containing the following patient mutations: P49L, P78R, A114V, R125Q, E176K, R266K, P422L, I435T, and S466L. These purified mutants exhibited full heme saturation, normal tetrameric assembly, and high catalytic activity. In this work, we used several spectroscopic and proteolytic techniques to provide a more thorough insight into the conformation of these mutant enzymes. Far-UV circular dichroism, fluorescence, and second-derivative UV spectroscopy revealed that the spatial arrangement of these CBS mutants is similar to that of the wild type, although the microenvironment of the chromophores may be slightly altered. Using proteolysis with thermolysin under native conditions, we found that the majority of the studied mutants is more susceptible to cleavage, suggesting their increased local flexibility or propensity for local unfolding. Interestingly, the presence of the CBS allosteric activator, S-adenosylmethionine (AdoMet), increased the rate of cleavage of the wild type and the AdoMet-responsive mutants, while the proteolytic rate of the AdoMet-unresponsive mutants was not significantly changed. Pulse proteolysis analysis suggested that the protein structure of the R125Q and E176K mutants is significantly less stable than that of the wild type and the other mutants. Taken together, the proteolytic data shows that the conformation of the pathogenic mutants is altered despite retained catalytic activity and normal tetrameric assembly. This study demonstrates that the proteolytic techniques are useful tools for the assessment of the biochemical penalty of missense mutations in CBS.
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Affiliation(s)
- Aleš Hnízda
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Ke Karlovu 2, 128 08 Prague 2, Czech Republic
| | - Tomas Majtan
- Department of Pediatrics and the Colorado Intellectual and Developmental Disabilities Research Center (IDDRC), University of Colorado at Denver, 12800 E 19th Ave, Aurora, Colorado 80045, USA
- Department of Genomics & Biotechnology, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, 84551, Slovakia
| | - Lu Liu
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado at Denver, Aurora, Colorado 80045, USA
| | - Angel L. Pey
- Department of Physical Chemistry, Faculty of Sciences, University of Granada, Granada 18071, Spain
| | - John F. Carpenter
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado at Denver, Aurora, Colorado 80045, USA
| | - Milan Kodíček
- Department of Biochemistry and Microbiology, Institute of Chemical Technology in Prague, Technická 5, 166 28, Prague 6, Czech Republic
| | - Viktor Kožich
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Ke Karlovu 2, 128 08 Prague 2, Czech Republic
| | - Jan P. Kraus
- Department of Pediatrics and the Colorado Intellectual and Developmental Disabilities Research Center (IDDRC), University of Colorado at Denver, 12800 E 19th Ave, Aurora, Colorado 80045, USA
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Majtan T, Kraus JP. Folding and activity of mutant cystathionine β-synthase depends on the position and nature of the purification tag: characterization of the R266K CBS mutant. Protein Expr Purif 2012; 82:317-24. [PMID: 22333527 DOI: 10.1016/j.pep.2012.01.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 01/25/2012] [Accepted: 01/29/2012] [Indexed: 10/14/2022]
Abstract
Cystathionine β-synthase (CBS), a heme-containing pyridoxal-5-phosphate (PLP)-dependent enzyme, catalyzes the condensation of serine and homocysteine to yield cystathionine. Missense mutations in CBS, the most common cause of homocystinuria, often result in misfolded proteins. Arginine 266, where the pathogenic missense mutation R266K was identified, appears to be involved in the communication between heme and the PLP-containing catalytic center. Here, we assessed the effect of a short affinity tag (6xHis) compared to a bulky fusion partner (glutathione S-transferase - GST) on CBS wild type (WT) and R266K mutant enzyme properties. While WT CBS was successfully expressed either in conjunction with a GST or with a 6xHis tag, the mutant R266K CBS had no activity, did not form native tetramers and did not respond to chemical chaperone treatment when expressed with a GST fusion partner. Interestingly, expression of R266K CBS constructs with a 6xHis tag at either end yielded active enzymes. The purified, predominantly tetrameric, R266K CBS with a C-terminal 6xHis tag had ∼82% of the activity of a corresponding WT CBS construct. Results from thermal pre-treatment of the enzyme and the denaturation profile of R266K suggests a lower thermal stability of the mutant enzyme compared to WT, presumably due to a disturbed heme environment.
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Affiliation(s)
- Tomas Majtan
- Department of Pediatrics and the Colorado Intellectual and Developmental Disabilities Research Center (IDDRC), University of Colorado, School of Medicine, 12800 E 19th Ave., Aurora, CO 80045, USA
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Swanson MA, Kathirvelu V, Majtan T, Frerman FE, Eaton GR, Eaton SS. Electron transfer flavoprotein domain II orientation monitored using double electron-electron resonance between an enzymatically reduced, native FAD cofactor, and spin labels. Protein Sci 2011; 20:610-20. [PMID: 21308847 DOI: 10.1002/pro.595] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Human electron transfer flavoprotein (ETF) is a soluble mitochondrial heterodimeric flavoprotein that links fatty acid β-oxidation to the main respiratory chain. The crystal structure of human ETF bound to medium chain acyl-CoA dehydrogenase indicates that the flavin adenine dinucleotide (FAD) domain (αII) is mobile, which permits more rapid electron transfer with donors and acceptors by providing closer access to the flavin and allows ETF to accept electrons from at least 10 different flavoprotein dehydrogenases. Sequence homology is high and low-angle X-ray scattering is identical for Paracoccus denitrificans (P. denitrificans) and human ETF. To characterize the orientations of the αII domain of P. denitrificans ETF, distances between enzymatically reduced FAD and spin labels in the three structural domains were measured by double electron-electron resonance (DEER) at X- and Q-bands. An FAD to spin label distance of 2.8 ± 0.15 nm for the label in the FAD-containing αII domain (A210C) agreed with estimates from the crystal structure (3.0 nm), molecular dynamics simulations (2.7 nm), and rotamer library analysis (2.8 nm). Distances between the reduced FAD and labels in αI (A43C) were between 4.0 and 4.5 ± 0.35 nm and for βIII (A111C) the distance was 4.3 ± 0.15 nm. These values were intermediate between estimates from the crystal structure of P. denitrificans ETF and a homology model based on substrate-bound human ETF. These distances suggest that the αII domain adopts orientations in solution that are intermediate between those which are observed in the crystal structures of free ETF (closed) and ETF bound to a dehydrogenase (open).
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Affiliation(s)
- Michael A Swanson
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, USA
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Smith AT, Majtan T, Freeman KM, Su Y, Kraus JP, Burstyn JN. Cobalt cystathionine β-synthase: a cobalt-substituted heme protein with a unique thiolate ligation motif. Inorg Chem 2011; 50:4417-27. [PMID: 21480614 PMCID: PMC3350334 DOI: 10.1021/ic102586b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Human cystathionine β-synthase (hCBS), a key enzyme in the trans-sulfuration pathway, catalyzes the condensation of serine with homocysteine to produce cystathionine. CBS from higher organisms is the only known protein that binds pyridoxal-5'-phosphate (PLP) and heme. Intriguingly, the function of the heme in hCBS has yet to be elucidated. Herein, we describe the characterization of a cobalt-substituted variant of hCBS (Co hCBS) in which CoPPIX replaces FePPIX (heme). Co(III) hCBS is a unique Co-substituted heme protein: the Co(III) ion is 6-coordinate, low-spin, diamagnetic, and bears a cysteine(thiolate) as one of its axial ligands. The peak positions and intensities of the electronic absorption and MCD spectra of Co(III) hCBS are distinct from those of previously Co-substituted heme proteins; TD-DFT calculations reveal that the unique features arise from the 6-coordinate Co bound axially by cysteine(thiolate) and a neutral donor, presumably histidine. Reactivity of Co(III) hCBS with HgCl(2) is consistent with a loss of the cysteine(thiolate) ligand. Co(III) hCBS is slowly reduced to Co(II) hCBS, which contains a 5-coordinate, low-spin, S = 1/2 Co-porphyrin that does not retain the cysteine(thiolate) ligand; this form of Co(II) hCBS binds NO((g)) but not CO((g)). Co(II) hCBS is reoxidized in the air to form a new Co(III) form, which does not contain a cysteine(thiolate) ligand. Canonical and alternative CBS assays suggest that maintaining the native heme ligation motif of wild-type Fe hCBS (Cys/His) is essential in maintaining maximal activity in Co hCBS. Correlation between the coordination structures and enzyme activity in both native Fe and Co-substituted proteins implicates a structural role for the heme in CBS.
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Affiliation(s)
- Aaron T. Smith
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin, 53706 USA
| | - Tomas Majtan
- Department of Pediatrics, University of Colorado Denver, Aurora, Colorado 80045
- Department of Genomics & Biotechnology, Institute of Molecular Biology SAS, Dubravska cesta 21, Bratislava, 84551, Slovakia
| | - Katherine M. Freeman
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin, 53706 USA
| | - Yang Su
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin, 53706 USA
| | - Jan P. Kraus
- Department of Pediatrics, University of Colorado Denver, Aurora, Colorado 80045
| | - Judith N. Burstyn
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin, 53706 USA
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Majtan T, Freeman KM, Smith AT, Burstyn JN, Kraus JP. Purification and characterization of cystathionine β-synthase bearing a cobalt protoporphyrin. Arch Biochem Biophys 2011; 508:25-30. [PMID: 21262193 PMCID: PMC3063419 DOI: 10.1016/j.abb.2011.01.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 01/14/2011] [Accepted: 01/15/2011] [Indexed: 11/24/2022]
Abstract
Human cystathionine β-synthase (CBS), a pivotal enzyme in the metabolism of homocysteine, is a pyridoxal-5'-phosphate-dependent enzyme that also contains heme, a second cofactor whose function is still unclear. One strategy for elucidation of heme function is its replacement with different metalloporphyrins or with porphyrins containing different substituent groups. This paper describes a novel expression approach and purification of cobalt CBS (CoCBS), which results in a high yield of fully active, high purity enzyme, in which heme is substituted by Co-protoporphyrin IX (CoPPIX). Metal content analysis showed that the enzyme contained 92% cobalt and 8% iron. CoCBS was indistinguishable from wild-type FeCBS in its activity, tetrameric oligomerization, PLP saturation and responsiveness to the allosteric activator, S-adenosyl-l-methionine. The observed biochemical and spectral characteristics of CoCBS provide further support for the suggestion that heme is involved in structural integrity and folding of this unusual enzyme.
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Affiliation(s)
- Tomas Majtan
- Department of Pediatrics and the Colorado Intellectual and Developmental Disabilities Research Center (IDDRC), University of Colorado at Denver, 12800 E 19th Ave, Aurora, CO 80045, USA
- Department of Genomics & Biotechnology, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, 84551, Slovakia
| | | | - Aaron T. Smith
- Department of Chemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Judith N. Burstyn
- Department of Chemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Jan P. Kraus
- Department of Pediatrics and the Colorado Intellectual and Developmental Disabilities Research Center (IDDRC), University of Colorado at Denver, 12800 E 19th Ave, Aurora, CO 80045, USA
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Majtan J, Kumar P, Majtan T, Walls AF, Klaudiny J. Effect of honey and its major royal jelly protein 1 on cytokine and MMP-9 mRNA transcripts in human keratinocytes. Exp Dermatol 2011; 19:e73-9. [PMID: 19845754 DOI: 10.1111/j.1600-0625.2009.00994.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Honey has been used since ancient times as a remedy in wound healing. However, even though the results from randomized clinical trials document that honey accelerates wound healing, no study dealing with its influence on human skin cells (epidermal keratinocytes and dermal fibroblast) has been performed. We demonstrate that keratinocytes, which are known to be involved in wound healing, are responsible for elevated production of mediators including cytokines (TNF-alpha, IL-1beta and TGF-beta) and matrix metalloproteinase-9 (MMP-9) after incubation with honey. Real-time PCR was performed for the quantification of mRNA level of selected cytokines and MMP-9. Furthermore, we show that the increased level of MMP-9 in the epidermis following incubation with honey leads to degradation of type IV collagen in the basement membrane. These data indisputably demonstrate that honey activates keratinocytes and support the findings that honey may accelerate wound healing process.
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Affiliation(s)
- Juraj Majtan
- Institute of Zoology, Slovak Academy of Sciences, Bratislava, Slovakia.
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Majtan T, Frerman FE, Kraus JP. Effect of cobalt on Escherichia coli metabolism and metalloporphyrin formation. Biometals 2010; 24:335-47. [PMID: 21184140 DOI: 10.1007/s10534-010-9400-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 12/14/2010] [Indexed: 02/01/2023]
Abstract
Toxicity in Escherichia coli resulting from high concentrations of cobalt has been explained by competition of cobalt with iron in various metabolic processes including Fe-S cluster assembly, sulfur assimilation, production of free radicals and reduction of free thiol pool. Here we present another aspect of increased cobalt concentrations in the culture medium resulting in the production of cobalt protoporphyrin IX (CoPPIX), which was incorporated into heme proteins including membrane-bound cytochromes and an expressed human cystathionine beta-synthase (CBS). The presence of CoPPIX in cytochromes inhibited their electron transport capacity and resulted in a substantially decreased respiration. Bacterial cells adapted to the increased cobalt concentration by inducing a modified mixed acid fermentative pathway under aerobiosis. We capitalized on the ability of E. coli to insert cobalt into PPIX to carry out an expression of CoPPIX-substituted heme proteins. The level of CoPPIX-substitution increased with the number of passages of cells in a cobalt-containing medium. This approach is an inexpensive method to prepare cobalt-substituted heme proteins compared to in vitro enzyme reconstitution or in vivo replacement using metalloporphyrin heme analogs and seems to be especially suitable for complex heme proteins with an additional coenzyme, such as human CBS.
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Affiliation(s)
- Tomas Majtan
- Department of Pediatrics and the Colorado Intellectual and Developmental Disabilities Research Center (IDDRC), University of Colorado at Denver, 12800 E 19th Ave, Aurora, CO 80045, USA
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Majtan T, Liu L, Carpenter JF, Kraus JP. Rescue of cystathionine beta-synthase (CBS) mutants with chemical chaperones: purification and characterization of eight CBS mutant enzymes. J Biol Chem 2010; 285:15866-73. [PMID: 20308073 DOI: 10.1074/jbc.m110.107722] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Missense mutations represent the most common cause of many genetic diseases including cystathionine beta-synthase (CBS) deficiency. Many of these mutations result in misfolded proteins, which lack biological function. The presence of chemical chaperones can sometimes alleviate or even restore protein folding and activity of mutant proteins. We present the purification and characterization of eight CBS mutants expressed in the presence of chemical chaperones such as ethanol, dimethyl sulfoxide, or trimethylamine-N-oxide. Preliminary screening in Escherichia coli crude extracts showed that their presence during protein expression had a significant impact on the amount of recovered CBS protein, formation of tetramers, and catalytic activity. Subsequently, we purified eight CBS mutants to homogeneity (P49L, P78R, A114V, R125Q, E176K, P422L, I435T, and S466L). The tetrameric mutant enzymes fully saturated with heme had the same or higher specific activities than wild type CBS. Thermal stability measurements demonstrated that the purified mutants are equally or more thermostable than wild type CBS. The response to S-adenosyl-L-methionine stimulation or thermal activation varied. The lack of response of R125Q and E176K to both stimuli indicated that their specific conformations were unable to reach the activated state. Increased levels of molecular chaperones in crude extracts, particularly DnaJ, indicated a rather indirect effect of the chemical chaperones on folding of CBS mutants. In conclusion, the chemical chaperones present in the expression medium were able to fully restore the activity of eight CBS mutants by improving their protein folding. This finding could have direct implications for the development of a therapeutical approach to pyridoxine unresponsive homocystinuria.
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Affiliation(s)
- Tomas Majtan
- Department of Pediatrics and the Colorado Intellectual and Developmental Disabilities Research Center, School of Medicine, University of Colorado at Denver, Aurora, Colorado 80045, USA
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Swanson MA, Kathirvelu V, Majtan T, Frerman FE, Eaton GR, Eaton SS. DEER distance measurement between a spin label and a native FAD semiquinone in electron transfer flavoprotein. J Am Chem Soc 2010; 131:15978-9. [PMID: 19886689 DOI: 10.1021/ja9059816] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The human mitochondrial electron transfer flavoprotein (ETF) accepts electrons from at least 10 different flavoprotein dehydrogenases and transfers electrons to a single electron acceptor in the inner membrane. Paracoccus denitrificans ETF has the identical function, shares the same three-dimensional structure and functional domains, and exhibits the same conformational mobility. It has been proposed that the mobility of the alphaII domain permits the promiscuous behavior of ETF with respect to a variety of redox partners. Double electron-electron resonance (DEER) measurements between a spin label and an enzymatically reduced flavin adenine dinucleotide (FAD) cofactor in P. denitrificans ETF gave two distributions of distances: a major component centered at 4.2 +/- 0.1 nm and a minor component centered at 5.1 +/- 0.2 nm. Both components had widths of approximately 0.3 nm. A distance of 4.1 nm was calculated using the crystal structure of P. denitrificans ETF, which agrees with the major component obtained from the DEER measurement. The observation of a second distribution suggests that ETF, in the absence of substrate, adopts some conformations that are intermediate between the predominant free and substrate-bound states.
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Affiliation(s)
- Michael A Swanson
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, USA
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Majtan T, Singh LR, Wang L, Kruger WD, Kraus JP. Active cystathionine beta-synthase can be expressed in heme-free systems in the presence of metal-substituted porphyrins or a chemical chaperone. J Biol Chem 2008; 283:34588-95. [PMID: 18849566 PMCID: PMC2596375 DOI: 10.1074/jbc.m805928200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 10/06/2008] [Indexed: 11/06/2022] Open
Abstract
Cystathionine beta-synthase (CBS), a key enzyme in the metabolism of homocysteine, has previously been shown to require a heme co-factor for maximal activity. However, the biochemical function of the CBS heme is not well defined. Here, we show that expression of human CBS in heme-deficient strains of Saccharomyces cerevisiae and Escherichia coli results in production of an enzyme that is misfolded and degraded. Addition of exogenous heme, porphyrins with non-iron metal, or porphyrin lacking metal entirely produced stable and active CBS enzyme. Purification of recombinant CBS enzyme expressed in the presence of various metalloporphyrins confirmed that Mn(III) and Co(III) had 30-60% of the specific activity of Fe(III)-CBS, and still responded to allosteric activation by S-adenosyl-L-methionine. Treatment of S. cerevisiae with the chemical chaperone trimethylamine-N-oxide resulted in near complete restoration of function to human CBS produced in a heme-deficient strain. Taken together, these results suggest that porphyrin moiety of the heme plays a critical role in proper CBS folding and assembly, but that the metal ion is not essential for this function or for allosteric regulation by S-adenosyl-L-methionine.
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Affiliation(s)
- Tomas Majtan
- Department of Pediatrics, University of Colorado, Denver, Aurora, Colorado 80045, USA
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Majtan T, Majtanova L, Timko J, Majtan V. Oligonucleotide microarray for molecular characterization and genotyping of Salmonella spp. strains. J Antimicrob Chemother 2007; 60:937-46. [PMID: 17897936 DOI: 10.1093/jac/dkm326] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
OBJECTIVES To characterize and subtype multidrug-resistant Salmonella isolates by determining the virulence factors, prophage sequences and antimicrobial resistance genes using a novel Salmonella-specific oligonucleotide microarray. METHODS Preliminary screening of 24 Salmonella clinical isolates was carried out by using susceptibility testing, plasmid profiling and class 1 integron PCR. Subsequently, oligonucleotide microarray was involved in genotypic characterization and localization of monitored genetic markers. The presence of antimicrobial resistance genes was also detected and confirmed by PCR and subsequent sequencing. The potential spread of emerging bla(SHV-2) was investigated by bacterial conjugation. RESULTS All Salmonella strains revealed resistance to two or more (up to nine) antibiotics. Nineteen of them carried class 1 integrons including dfrA1, dfrA12, aadA1, aadA2, bla(PSE-1) and bla(TEM-1) gene cassettes, respectively. Twenty-three out of 24 Salmonella isolates possessed one or more plasmids. Oligonucleotide microarray characterization and typing revealed the conserved character of Salmonella pathogenicity island virulence factors among three Salmonella enterica serovars, significant variability in prophage sequences and many different antimicrobial resistance gene patterns. Differential labelling of genomic and plasmid DNA, respectively, and hybridization to the microarray made it possible to localize important resistance determinants. Microarray results were successfully confirmed and verified by using PCR. The emerging bla(SHV-2) gene from Salmonella Kentucky SK10944 conferring resistance to ceftriaxone and cefotaxime was transferred via bacterial conjugation to Escherichia coli K-12 3110. CONCLUSIONS Salmonella isolates were quickly and thoroughly characterized by a novel oligonucleotide microarray, which could become a useful tool for detection of virulence and resistance genes and monitoring of their dissemination among salmonellae and closely related bacteria.
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Affiliation(s)
- T Majtan
- Department of Genomics and Biotechnology, Institute of Molecular Biology SAS, Dubravska cesta 21, 84551 Bratislava 45, Slovakia.
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Majtan T, Halgasova N, Bukovska G, Timko J. Transcriptional profiling of bacteriophage BFK20: Coexpression interrogated by “guilt-by-association” algorithm. Virology 2007; 359:55-65. [PMID: 17052739 DOI: 10.1016/j.virol.2006.09.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Revised: 09/04/2006] [Accepted: 09/19/2006] [Indexed: 10/24/2022]
Abstract
Global gene expression profiling of bacteriophage BFK20 infecting the industrial L-lysine producer Brevibacterium flavum CCM 251 was performed using DNA microarray. The relative gene expressions were measured in fourteen time samples collected during phage development. Phage genes were classified as early, middle, late or unassigned based on complex expression patterns during infection. Temporal classification of BFK20 genes was in concordance with previous predictions. However, proposed late regulatory genes were reclassified and new functional assignments for ORF55 were strongly suggested. Furthermore, we consider possible functions of other genes and their products regarding coexpression pattern by using "guilt-by-association" algorithm. Microarray results were validated using real-time RT-PCR. The detailed description of phage BFK20 transcriptional profile can answer the basic questions of its life cycle and it also can help to prevent phage contamination during industrial fermentation. In addition, this work presents the first complete microarray time course study of gene expression utilizing loop design.
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Affiliation(s)
- Tomas Majtan
- Institute of Molecular Biology, Slovak Academy of Sciences, Dubravska cesta 21, 845 51 Bratislava 45, Slovakia.
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