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Enemark JH. Mechanistic complexities of sulfite oxidase: An enzyme with multiple domains, subunits, and cofactors. J Inorg Biochem 2023; 247:112312. [PMID: 37441922 DOI: 10.1016/j.jinorgbio.2023.112312] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 05/13/2023] [Accepted: 07/01/2023] [Indexed: 07/15/2023]
Abstract
Sulfite oxidase (SO) deficiency, an inherited disease that causes severe neonatal neurological problems and early death, arises from defects in the biosynthesis of the molybdenum cofactor (Moco) (general sulfite oxidase deficiency) or from inborn errors in the SUOX gene for SO (isolated sulfite oxidase deficiency, ISOD). The X-ray structure of the highly homologous homonuclear dimeric chicken sulfite oxidase (cSO) provides a template for locating ISOD mutation sites in human sulfite oxidase (hSO). Catalysis occurs within an individual subunit of hSO, but mutations that disrupt the hSO dimer are pathological. The catalytic cycle of SO involves five metal oxidation states (MoVI, MoV, MoIV, FeIII, FeII), two intramolecular electron transfer (IET) steps, and couples a two-electron oxygen atom transfer reaction at the Mo center with two one-electron transfers from the integral b-type heme to exogenous cytochrome c, the physiological oxidant. Several ISOD examples are analyzed using steady-state, stopped-flow, and laser flash photolysis kinetics and physical measurements of recombinant variants of hSO and native cSO. In the structure of cSO, Mo…Fe = 32 Å, much too long for efficient IET through the protein. Interdomain motion that brings the Mo and heme centers closer together to facilitate IET is supported indirectly by decreasing the length of the interdomain tether, by changes in the charges of surface residues of the Mo and heme domains, as well as by preliminary molecular dynamics calculations. However, direct dynamic measurements of interdomain motion are in their infancy.
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Affiliation(s)
- John H Enemark
- Department of Chemistry and Biochemistry, The University of Arizona, 1306 East University Blvd, Tucson, AZ 85721-0041, United States of America.
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Zhao J, An Y, Jiang H, Wu H, Che F, Yang Y. Novel Compound Heterozygous Pathogenic Variants in SUOX Cause Isolated Sulfite Oxidase Deficiency in a Chinese Han Family. Front Genet 2021; 12:607085. [PMID: 34025712 PMCID: PMC8139553 DOI: 10.3389/fgene.2021.607085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 04/13/2021] [Indexed: 11/13/2022] Open
Abstract
Aim To explore the clinical imaging, laboratory and genetic characteristics of a newborn boy with isolated sulfite oxidase deficiency (ISOD) in a Chinese mainland cohort. Methods Homocysteine and uric acid in plasma and cysteine and total homocysteine in the blood spot were assessed in a Chinese newborn patient with progressive encephalopathy, tonic seizures, abnormal muscle tone, and feeding difficulties. Whole exome sequencing and Sanger sequencing facilitated an accurate diagnosis. The pathogenicity predictions and conservation analysis of the identified mutations were conducted by bioinformatics tools. Results Low total homocysteine was detected in the blood spot, while homocysteine and uric acid levels were normal in the plasma. S-sulfocysteine was abnormally elevated in urine. A follow-up examination revealed several progressive neuropathological findings. Also, intermittent convulsions and axial dystonia were observed. However, the coordination of sucking and swallowing was slightly improved. A novel paternal nonsense variant c.475G > T (p.Glu159∗) and a novel maternal missense variant c.1201A > G (p.Lys401Glu) in SUOX were identified in this case by co-segregation verification. Conclusion This is the second report of early-onset ISOD case in a non-consanguineous Chinese mainland family. Combined with the clinical characteristics and biochemical indexes, we speculated that these two novel pathogenic variants of the SUOX gene underlie the cause of the disease in this patient. Next-generation sequencing (NGS) and Sanger sequencing provided reliable basis for clinical and prenatal diagnoses of this family, it also enriched the mutation spectrum of the SUOX gene.
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Affiliation(s)
- Jiangang Zhao
- Department of Neonatology, Xi'an Children's Hospital, Xi'an, China
| | - Yao An
- Department of Neonatology, Xi'an Children's Hospital, Xi'an, China
| | - Haoxiang Jiang
- Department of Radiology, Xi'an Children's Hospital, Xi'an, China
| | - Haibin Wu
- Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Xi'an, China
| | - Fengyu Che
- Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Xi'an, China
| | - Ying Yang
- Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Xi'an, China
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Misko AL, Liang Y, Kohl JB, Eichler F. Delineating the phenotypic spectrum of sulfite oxidase and molybdenum cofactor deficiency. Neurol Genet 2020; 6:e486. [PMID: 32802950 PMCID: PMC7371372 DOI: 10.1212/nxg.0000000000000486] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 06/08/2020] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To define the phenotypic spectrum of isolated sulfite oxidase (ISOD) and molybdenum cofactor deficiency (MoCD), aiming to promote timely diagnosis and assist in future clinical trial design. METHODS We analyzed clinical, radiographic, biochemical, and genetic data from 146 patients reported in the literature. RESULTS We stratified patients into 2 phenotypic subgroups based on clinical and radiographic characteristics. In the first (Class I), patients presented early in life (age 1-50 days) with acute onset of neurologic symptoms and development of diffuse brain injury with cystic leukomalacia. Patients in the second subgroup (Class II) presented later in life (age 30 days-23 years) with prominent movement abnormalities and selective injury of the basal ganglia and cerebellum. A significant difference in survival estimates correlated with milder disease severity among Class II patients. Substantial overlap in sulfur-containing metabolite levels prevented discrimination of subgroups based on diagnostic biomarkers, but genotype-phenotype correlations suggested that residual SUOX activity may contribute to milder phenotypes. CONCLUSIONS Patients with SUOX and MoCD gravitate toward 1 of 2 distinct clinicoradiographic profiles. Patient stratification may help promote accurate diagnosis, prognostication, and aid in the design of future clinical trials.
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Affiliation(s)
- Albert L Misko
- Departments of Neurology (A.L.M., Y.L., F.E.), Massachusetts General Hospital and Harvard Medical School, Boston; and the Department of Chemistry (J.B.K.), Institute of Biochemistry, University of Cologne, Germany
| | - Ye Liang
- Departments of Neurology (A.L.M., Y.L., F.E.), Massachusetts General Hospital and Harvard Medical School, Boston; and the Department of Chemistry (J.B.K.), Institute of Biochemistry, University of Cologne, Germany
| | - Joshua B Kohl
- Departments of Neurology (A.L.M., Y.L., F.E.), Massachusetts General Hospital and Harvard Medical School, Boston; and the Department of Chemistry (J.B.K.), Institute of Biochemistry, University of Cologne, Germany
| | - Florian Eichler
- Departments of Neurology (A.L.M., Y.L., F.E.), Massachusetts General Hospital and Harvard Medical School, Boston; and the Department of Chemistry (J.B.K.), Institute of Biochemistry, University of Cologne, Germany
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Wang W, Wang B. SO 2 Donors and Prodrugs, and Their Possible Applications: A Review. Front Chem 2018; 6:559. [PMID: 30505833 PMCID: PMC6250732 DOI: 10.3389/fchem.2018.00559] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 10/29/2018] [Indexed: 12/16/2022] Open
Abstract
SO2 is widely recognized as an air pollutant and is a known cause of acid rain. At a sufficiently high level, it also causes respiratory diseases. A much lesser known side of SO2 is its endogenous nature and possible physiological roles. There is mounting evidence that SO2 is produced during normal cellular metabolism and may possibly function as a signaling molecule in normal physiology. The latter aspect is still at the stage of being carefully examined as to the validity of classifying SO2 as a gasotransmitter with endogenous signaling roles. One difficulty in studying the biological and pharmacological roles of SO2 is the lack of adequate tools for its controllable and precise delivery. Traditional methods of using SO2 gas or mixed sulfite salts do not meet research need for several reasons. Therefore, there has been increasing attention on the need of developing SO2 donors or prodrugs that can be used as tools for the elucidation of SO2's physiological roles, pharmacological effects, and possible mechanism(s) of action. In this review, we aim to review basic sulfur chemistry in the context of sulfur signaling and various chemical strategies used for designing SO2 donors. We will also discuss potential pharmacological applications of SO2 donors, lay out desirable features for such donors and possibly prodrugs, analyze existing problems, and give our thoughts on research needs.
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Affiliation(s)
| | - Binghe Wang
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, United States
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Kenneth CN, Samuel OA, Chibueze N, Michael PO. Radiation protection and anti-oxidative effects of garlic, onion and ginger extracts, x-ray exposed albino rats as model for biochemical studies. ACTA ACUST UNITED AC 2014. [DOI: 10.5897/ajbr2014.0794] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Ensafi AA, Heydari-Bafrooei E, Rezaei B. DNA-Based Biosensor for Comparative Study of Catalytic Effect of Transition Metals on Autoxidation of Sulfite. Anal Chem 2012; 85:991-7. [DOI: 10.1021/ac302693j] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Ali A. Ensafi
- Department of Chemistry, Isfahan University of Technology, Isfahan 84156−83111, Iran
| | | | - Behzad Rezaei
- Department of Chemistry, Isfahan University of Technology, Isfahan 84156−83111, Iran
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Affiliation(s)
- Carola Schulzke
- School of Chemistry, Trinity College Dublin, Dublin 2, Ireland
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Kappler U. Bacterial sulfite-oxidizing enzymes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:1-10. [DOI: 10.1016/j.bbabio.2010.09.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2010] [Revised: 09/05/2010] [Accepted: 09/14/2010] [Indexed: 11/25/2022]
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Bailey S, Rapson T, Johnson-Winters K, Astashkin AV, Enemark JH, Kappler U. Molecular basis for enzymatic sulfite oxidation: how three conserved active site residues shape enzyme activity. J Biol Chem 2009; 284:2053-63. [PMID: 19004819 PMCID: PMC2629113 DOI: 10.1074/jbc.m807718200] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Revised: 11/12/2008] [Indexed: 11/06/2022] Open
Abstract
Sulfite dehydrogenases (SDHs) catalyze the oxidation and detoxification of sulfite to sulfate, a reaction critical to all forms of life. Sulfite-oxidizing enzymes contain three conserved active site amino acids (Arg-55, His-57, and Tyr-236) that are crucial for catalytic competency. Here we have studied the kinetic and structural effects of two novel and one previously reported substitution (R55M, H57A, Y236F) in these residues on SDH catalysis. Both Arg-55 and His-57 were found to have key roles in substrate binding. An R55M substitution increased Km(sulfite)(app) by 2-3 orders of magnitude, whereas His-57 was required for maintaining a high substrate affinity at low pH when the imidazole ring is fully protonated. This effect may be mediated by interactions of His-57 with Arg-55 that stabilize the position of the Arg-55 side chain or, alternatively, may reflect changes in the protonation state of sulfite. Unlike what is seen for SDHWT and SDHY236F, the catalytic turnover rates of SDH R55M and SDHH57A are relatively insensitive to pH (approximately 60 and 200 s(-1), respectively). On the structural level, striking kinetic effects appeared to correlate with disorder (in SDHH57A and SDHY236F) or absence of Arg-55 (SDHR55M), suggesting that Arg-55 and the hydrogen bonding interactions it engages in are crucial for substrate binding and catalysis. The structure of SDHR55M has sulfate bound at the active site, a fact that coincides with a significant increase in the inhibitory effect of sulfate in SDHR55M. Thus, Arg-55 also appears to be involved in enabling discrimination between the substrate and product in SDH.
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Affiliation(s)
- Susan Bailey
- Molecular Biophysics Group, Science and Technology Facilities Council Daresbury Laboratory, Warrington WA4 4AD, United Kingdom
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Feng C, Tollin G, Enemark JH. Sulfite oxidizing enzymes. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2007; 1774:527-39. [PMID: 17459792 PMCID: PMC1993547 DOI: 10.1016/j.bbapap.2007.03.006] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2007] [Revised: 03/02/2007] [Indexed: 11/19/2022]
Abstract
Sulfite oxidizing enzymes are essential mononuclear molybdenum (Mo) proteins involved in sulfur metabolism of animals, plants and bacteria. There are three such enzymes presently known: (1) sulfite oxidase (SO) in animals, (2) SO in plants, and (3) sulfite dehydrogenase (SDH) in bacteria. X-ray crystal structures of enzymes from all three sources (chicken SO, Arabidopsis thaliana SO, and Starkeya novella SDH) show nearly identical square pyramidal coordination around the Mo atom, even though the overall structures of the proteins and the presence of additional cofactors vary. This structural information provides a molecular basis for studying the role of specific amino acids in catalysis. Animal SO catalyzes the final step in the degradation of sulfur-containing amino acids and is critical in detoxifying excess sulfite. Human SO deficiency is a fatal genetic disorder that leads to early death, and impaired SO activity is implicated in sulfite neurotoxicity. Animal SO and bacterial SDH contain both Mo and heme domains, whereas plant SO only has the Mo domain. Intraprotein electron transfer (IET) between the Mo and Fe centers in animal SO and bacterial SDH is a key step in the catalysis, which can be studied by laser flash photolysis in the presence of deazariboflavin. IET studies on animal SO and bacterial SDH clearly demonstrate the similarities and differences between these two types of sulfite oxidizing enzymes. Conformational change is involved in the IET of animal SO, in which electrostatic interactions may play a major role in guiding the docking of the heme domain to the Mo domain prior to electron transfer. In contrast, IET measurements for SDH demonstrate that IET occurs directly through the protein medium, which is distinctly different from that in animal SO. Point mutations in human SO can result in significantly impaired IET or no IET, thus rationalizing their fatal effects. The recent developments in our understanding of sulfite oxidizing enzyme mechanisms that are driven by a combination of molecular biology, rapid kinetics, pulsed electron paramagnetic resonance (EPR), and computational techniques are the subject of this review.
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Affiliation(s)
- Changjian Feng
- College of Pharmacy, University of New Mexico, Albuquerque, NM 87131
| | - Gordon Tollin
- Department of Biochemistry and Molecular Biophysics, University of Arizona, Tucson, Arizona 85721, USA
| | - John H. Enemark
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA
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Garner D, McMaster J, Raven E, Walton P. Dalton Discussion No. 8. Metals: centres of biological activity. Dalton Trans 2005:3372-4. [PMID: 16234913 DOI: 10.1039/b513314a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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