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Badr H, Nabil NM, Tawakol MM. Effects of the prebiotic lactoferrin on multidrug-resistant Escherichia coli infections in broiler chickens. Vet World 2021; 14:2197-2205. [PMID: 34566339 PMCID: PMC8448632 DOI: 10.14202/vetworld.2021.2197-2205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 07/07/2021] [Indexed: 01/05/2023] Open
Abstract
Background and Aim Increased multidrug resistance in Escherichia coli has created challenges for the poultry industry. Consequently, new antimicrobial agents should preferentially be utilized for the prevention and treatment of E. coli outbreaks. This study aimed to evaluate the effects of lactoferrin (LF) as a prebiotic on broiler chicks challenged with multidrug-resistant E. coli in comparison with antibiotics. Materials and Methods A total of 70 diseased flocks from Egypt were collected for E. coli isolation and identification, serotyping, and antimicrobial susceptibility pattern determination. E. coli was isolated and characterized phenotypically and one isolate that showed multidrug-resistance was selected. A challenge trial was performed to evaluate the effectiveness of LF as a prebiotic on the isolated multidrug-resistant E. coli. Liver samples were collected from the experimental chicks and subjected to E. coli enumeration to illustrate the effectiveness of LF on the liver cells and bacteria using an electron microscope. Serum samples were also collected to estimate lysozyme and nitric oxide (NO) concentrations. Results After isolation of E. coli with a percentage of 54.3% from the diseased broilers, the strain was serotyped (identified serotypes: O2, O18, O55, O78, O86a, O111, O125, O126, O127, O157, O159, and O166). Multi-antibiotic resistance was found to be harbored in a high percentage among 11 antibiotic discs. The LF in the prophylactic and treated groups was found to have a significant effect in comparison with the group treated with the drug of choice (ciprofloxacin). Furthermore, a significant difference in the NO (one of non-specific immune response) and a non-significant difference in lysozyme concentrations were reported in the group fed on rations with LF in comparison with the non-fed group. Conclusion LF was thus identified as an effective prebiotic that can improve chick performance, help them to overcome multidrug-resistant E. coli and stimulate immunity.
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Affiliation(s)
- Heba Badr
- Department of Bacteriology, Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agricultural Research Center, Nadi El-Seid Street, Dokki, Giza 12618, Egypt
| | - Nehal M Nabil
- Department of Bacteriology, Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agricultural Research Center, Nadi El-Seid Street, Dokki, Giza 12618, Egypt
| | - Maram M Tawakol
- Department of Bacteriology, Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agricultural Research Center, Nadi El-Seid Street, Dokki, Giza 12618, Egypt
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Crystal structure of tert-butyl-3-(4-oxo-2-thioxo-3,4-dihydropyrimidin- 1(2H)-yl)propanoate, C11H15N2O3S. Z KRIST-NEW CRYST ST 2012. [DOI: 10.1524/ncrs.2012.0245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Majumdar U, Biswas P, Subhra Sarkar T, Maiti D, Ghosh S. Regulation of cell cycle and stress responses under nitrosative stress in Schizosaccharomyces pombe. Free Radic Biol Med 2012; 52:2186-200. [PMID: 22561704 DOI: 10.1016/j.freeradbiomed.2012.03.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 03/13/2012] [Accepted: 03/30/2012] [Indexed: 02/07/2023]
Abstract
Nitric oxide (NO) acts as a signaling molecule in numerous physiological processes but excess production generates nitrosative stress in cells. The exact protective mechanism used by cells to combat nitrosative stress is unclear. In this study, the fission yeast Schizosaccharomyces pombe has been used as a model system to explore cell cycle regulation and stress responses under nitrosative stress. Exposure to an NO donor results in mitotic delay in cells through G2/M checkpoint activation and initiates rereplication. Western blot analysis of phosphorylated Cdc2 revealed that the G2/M block in the cell cycle was due to retention of its inactive phosphorylated form. Interestingly, nitrosative stress results in inactivation of Cdc25 through S-nitrosylation that actually leads to cell cycle delay. From differential display analysis, we identified plo1, spn4, and rga5, three cell cycle-related genes found to be differentially expressed under nitrosative stress. Exposure to nitrosative stress also results in abnormal septation and cytokinesis in S. pombe. In summary we propose a novel molecular mechanism of cell cycle control under nitrosative stress based on our experimental results and bioinformatics analysis.
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Affiliation(s)
- Uddalak Majumdar
- Department of Biochemistry, University College of Science, Calcutta University, Kolkata 700019, West Bengal, India
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Wang ZQ, Tejero J, Wei CC, Haque MM, Santolini J, Fadlalla M, Biswas A, Stuehr DJ. Arg375 tunes tetrahydrobiopterin functions and modulates catalysis by inducible nitric oxide synthase. J Inorg Biochem 2012; 108:203-15. [PMID: 22173094 PMCID: PMC3306459 DOI: 10.1016/j.jinorgbio.2011.11.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2011] [Revised: 11/12/2011] [Accepted: 11/14/2011] [Indexed: 10/15/2022]
Abstract
NO synthase enzymes (NOS) support unique single-electron transitions of a bound H(4)B cofactor during catalysis. Previous studies showed that both the pterin structure and surrounding protein residues impact H(4)B redox function during catalysis. A conserved Arg residue (Arg375 in iNOS) forms hydrogen bonds with the H(4)B ring. In order to understand the role of this residue in modulating the function of H(4)B and overall NO synthesis of the enzyme, we generated and characterized three mutants R375D, R375K and R375N of the oxygenase domain of inducible NOS (iNOSoxy). The mutations affected the dimer stability of iNOSoxy and its binding affinity toward substrates and H(4)B to varying degrees. Optical spectra of the ferric, ferrous, ferrous dioxy, ferrous-NO, ferric-NO, and ferrous-CO forms of each mutant were similar to the wild-type. However, mutants displayed somewhat lower heme midpoint potentials and faster ferrous heme-NO complex reactivity with O(2). Unlike the wild-type protein, mutants could not oxidize NOHA to nitrite in a H(2)O(2)-driven reaction. Mutation could potentially change the ferrous dioxy decay rate, H(4)B radical formation rate, and the amount of the Arg hydroxylation during single turnover Arg hydroxylation reaction. All mutants were able to form heterodimers with the iNOS G450A full-length protein and displayed lower NO synthesis activities and uncoupled NADPH consumption. We conclude that the conserved residue Arg375 (1) regulates the tempo and extent of the electron transfer between H(4)B and ferrous dioxy species and (2) controls the reactivity of the heme-based oxidant formed after electron transfer from H(4)B during steady state NO synthesis and H(2)O(2)-driven NOHA oxidation. Thus, Arg375 modulates the redox function of H(4)B and is important in controlling the catalytic function of NOS enzymes.
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Affiliation(s)
- Zhi-Qiang Wang
- Department of Chemistry and Biochemistry, Kent State University at Tuscarawas, New Philadelphia, Ohio, 44663
| | - Jesús Tejero
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio, 44195
| | - Chin-Chuan Wei
- Department of Chemistry, Southern Illinois University Edwardsville, Edwardsville, IL, 62026
| | - Mohammad Mahfuzul Haque
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio, 44195
| | - Jerome Santolini
- iBiTec-S; LSOD, C. E. A. Saclay; 91191 Gif-sur-Yvette Cedex, France
| | - Mohammed Fadlalla
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio, 44195
| | - Ashis Biswas
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio, 44195
| | - Dennis J. Stuehr
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio, 44195
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5
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Tejero J, Haque MM, Durra D, Stuehr DJ. A bridging interaction allows calmodulin to activate NO synthase through a bi-modal mechanism. J Biol Chem 2010; 285:25941-9. [PMID: 20529840 DOI: 10.1074/jbc.m110.126797] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calmodulin (CaM) activates the nitric-oxide synthases (NOS) by a mechanism that is not completely understood. A recent crystal structure showed that bound CaM engages in a bridging interaction with the NOS FMN subdomain. We investigated its importance in neuronal NOS (nNOS) by mutating the two residues that primarily create the bridging interaction (Arg(752) in the FMN subdomain and Glu(47) in CaM). Mutations designed to completely destroy the bridging interaction prevented bound CaM from increasing electron flux through the FMN subdomain and diminished the FMN-to-heme electron transfer by 90%, whereas mutations that partly preserve the interaction had intermediate effects. The bridging interaction appeared to control FMN subdomain interactions with both its electron donor (NADPH-FAD subdomain) and electron acceptor (heme domain) partner subdomains in nNOS. We conclude that the Arg(752)-Glu(47) bridging interaction is the main feature that enables CaM to activate nNOS. The mechanism is bi-modal and links a single structural aspect of CaM binding to specific changes in nNOS protein conformational and electron transfer properties that are essential for catalysis.
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Affiliation(s)
- Jesús Tejero
- Department of Pathobiology, Lerner Research Institute, The Cleveland Clinic, Cleveland, Ohio 44195, USA
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6
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NO formation by a catalytically self-sufficient bacterial nitric oxide synthase from Sorangium cellulosum. Proc Natl Acad Sci U S A 2009; 106:16221-6. [PMID: 19805284 DOI: 10.1073/pnas.0908443106] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The role of nitric oxide (NO) in the host response to infection and in cellular signaling is well established. Enzymatic synthesis of NO is catalyzed by the nitric oxide synthases (NOSs), which convert Arg into NO and citrulline using co-substrates O2 and NADPH. Mammalian NOS contains a flavin reductase domain (FAD and FMN) and a catalytic heme oxygenase domain (P450-type heme and tetrahydrobiopterin). Bacterial NOSs, while much less studied, were previously identified as only containing the heme oxygenase domain of the more complex mammalian NOSs. We report here on the characterization of a NOS from Sorangium cellulosum (both full-length, scNOS, and oxygenase domain, scNOSox). scNOS contains a catalytic, oxygenase domain similar to those found in the mammalian NOS and in other bacteria. Unlike the other bacterial NOSs reported to date, however, this protein contains a fused reductase domain. The scNOS reductase domain is unique for the entire NOS family because it utilizes a 2Fe2S cluster for electron transfer. scNOS catalytically produces NO and citrulline in the presence of either tetrahydrobiopterin or tetrahydrofolate. These results establish a bacterial electron transfer pathway used for biological NO synthesis as well as a unique flexibility in using different tetrahydropterin cofactors for this reaction.
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7
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Likhtenshtein GI. Novel Fluorescent Methods for Biotechnological and Biomedical Sensoring: Assessing Antioxidants, Reactive Radicals, NO Dynamics, Immunoassay, and Biomembranes Fluidity. Appl Biochem Biotechnol 2008; 152:135-55. [DOI: 10.1007/s12010-008-8219-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2008] [Accepted: 03/10/2008] [Indexed: 10/21/2022]
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8
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Pukala TL, Doyle JR, Llewellyn LE, Kuhn-Nentwig L, Apponyi MA, Separovic F, Bowie JH. Cupiennin 1a, an antimicrobial peptide from the venom of the neotropical wandering spider Cupiennius salei, also inhibits the formation of nitric oxide by neuronal nitric oxide synthase. FEBS J 2007; 274:1778-84. [PMID: 17313650 DOI: 10.1111/j.1742-4658.2007.05726.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cupiennin 1a (GFGALFKFLAKKVAKTVAKQAAKQGAKYVVNKQME-NH2) is a potent venom component of the spider Cupiennius salei. Cupiennin 1a shows multifaceted activity. In addition to known antimicrobial and cytolytic properties, cupiennin 1a inhibits the formation of nitric oxide by neuronal nitric oxide synthase at an IC50 concentration of 1.3 +/- 0.3 microM. This is the first report of neuronal nitric oxide synthase inhibition by a component of a spider venom. The mechanism by which cupiennin 1a inhibits neuronal nitric oxide synthase involves complexation with the regulatory protein calcium calmodulin. This is demonstrated by chemical shift changes that occur in the heteronuclear single quantum coherence spectrum of 15N-labelled calcium calmodulin upon addition of cupiennin 1a. The NMR data indicate strong binding within a complex of 1 : 1 stoichiometry.
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Affiliation(s)
- Tara L Pukala
- Department of Chemistry, The University of Adelaide, Australia
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9
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Sahoo R, Dutta T, Das A, Sinha Ray S, Sengupta R, Ghosh S. Effect of nitrosative stress on Schizosaccharomyces pombe: inactivation of glutathione reductase by peroxynitrite. Free Radic Biol Med 2006; 40:625-31. [PMID: 16458193 DOI: 10.1016/j.freeradbiomed.2005.09.029] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2005] [Revised: 08/23/2005] [Accepted: 09/12/2005] [Indexed: 11/26/2022]
Abstract
Oxidative stress has been shown to alter cellular redox status in various cell types. Changes in expressions of several antioxidative and antistress-responsive genes along with activation or inactivation of various proteins were also reported during oxidative insult as well as during nitrosative stress. In the present study, we show the effect of nitrosative stress on cellular redox status of fission yeast Schizosaccharomyces pombe. This is the first report of S-nitrosoglutathione (GSNO) reductase activity in S. pombe and its inactivation by GSNO. We also show the inactivation of glutathione reductase (GR) and glutathione peroxidase in the presence of various reactive nitrogen species in vivo. In addition, we first observe the inactivation of GR by peroxynitrite in vivo using S. pombe cells and also similar observations under in vitro conditions. An immunoreactive band against monoclonal anti-3-nitrotyrosine antibody confirms the modification of GR under in vitro conditions. We also show the effect of nitrosative stress on Deltapap1 cells of S. pombe, which are more sensitive to nitrosative stress, indicating the involvement of Pap1 in the protection against nitrosative stress. Finally, exposure of S. pombe cells to reactive nitrogen species reveals an important role of cellular thiol pool in protection against nitrosative stress.
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Affiliation(s)
- Rupam Sahoo
- Department of Biochemistry, Calcutta University, 35, Ballygunge Circular Road, Kolkata-700 019, India
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10
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Apponyi MA, Pukala TL, Brinkworth CS, Maselli VM, Bowie JH, Tyler MJ, Booker GW, Wallace JC, Carver JA, Separovic F, Doyle J, Llewellyn LE. Host-defence peptides of Australian anurans: structure, mechanism of action and evolutionary significance. Peptides 2004; 25:1035-54. [PMID: 15203252 DOI: 10.1016/j.peptides.2004.03.006] [Citation(s) in RCA: 172] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2003] [Revised: 03/10/2004] [Accepted: 03/11/2004] [Indexed: 11/26/2022]
Abstract
Host-defence peptides secreted from the skin glands of Australian frogs and toads, are, with a few notable exceptions, different from those produced by anurans elsewhere. This review summarizes the current knowledge of the following classes of peptide isolated and characterized from Australian anurans: neuropeptides (including smooth muscle active peptides, and peptides that inhibit the production of nitric oxide from neuronal nitric oxide synthase), antimicrobial and anticancer active peptides, antifungal peptides and antimalarial peptides. Other topics covered include sex pheromones of anurans, and the application of peptide profiling to (i). recognize particular populations of anurans of the same species and to differentiate between species, and (ii). investigate evolutionary aspects of peptide formation.
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Affiliation(s)
- Margit A Apponyi
- Department of Chemistry, The University of Adelaide, Adelaide, South Australia 5005, Australia
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11
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Wei CC, Wang ZQ, Hemann C, Hille R, Stuehr DJ. A tetrahydrobiopterin radical forms and then becomes reduced during Nomega-hydroxyarginine oxidation by nitric-oxide synthase. J Biol Chem 2003; 278:46668-73. [PMID: 14504282 DOI: 10.1074/jbc.m307682200] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nitric-oxide synthases are flavoheme enzymes that catalyze two sequential monooxygenase reactions to generate nitric oxide (NO) from l-arginine. We investigated a possible redox role for the enzyme-bound cofactor 6R-tetrahydrobiopterin (H4B) in the second reaction of NO synthesis, which is conversion of N-hydroxy-l-arginine (NOHA) to NO plus citrulline. We used stopped-flow spectroscopy and rapid-freeze EPR spectroscopy to follow heme and biopterin transformations during single-turnover NOHA oxidation reactions catalyzed by the oxygenase domain of inducible nitric-oxide synthase (iNOSoxy). Significant biopterin radical (>0.5 per heme) formed during reactions catalyzed by iNOSoxy that contained either H4B or 5-methyl-H4B. Biopterin radical formation was kinetically linked to conversion of a heme-dioxy intermediate to a heme-NO product complex. The biopterin radical then decayed within a 200-300-ms time period just prior to dissociation of NO from a ferric heme-NO product complex. Measures of final biopterin redox status showed that biopterin radical decay occurred via an enzymatic one-electron reduction process that regenerated H4B (or 5MeH4B). These results provide evidence of a dual redox function for biopterin during the NOHA oxidation reaction. The data suggest that H4B first provides an electron to a heme-dioxy intermediate, and then the H4B radical receives an electron from a downstream reaction intermediate to regenerate H4B. The first one-electron transition enables formation of the heme-based oxidant that reacts with NOHA, while the second one-electron transition is linked to formation of a ferric heme-NO product complex that can release NO from the enzyme. These redox roles are novel and expand our understanding of biopterin function in biology.
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Affiliation(s)
- Chin-Chuan Wei
- Department of Immunology, The Lerner Research Institute, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA
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12
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Sahoo R, Sengupta R, Ghosh S. Nitrosative stress on yeast: inhibition of glyoxalase-I and glyceraldehyde-3-phosphate dehydrogenase in the presence of GSNO. Biochem Biophys Res Commun 2003; 302:665-70. [PMID: 12646220 DOI: 10.1016/s0006-291x(03)00251-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Under nitrosative stressed condition intracellular GSNO accumulation is common to all cell types. Conserved NADH-dependent GSNO reductase was reported previously as an important cellular protective measure against this. In spite of the constitutive nature of the enzyme, we observed in vivo inactivation of two important enzymes-glyoxalase-I and glyceraldehyde-3-phosphate dehydrogenase under 5 mM GSNO stress in two budding yeasts, though with difference in their sensitivity. Former was more susceptible to inactivation in in vitro condition, too. In this study, we explored the competitive nature of yeast glyoxalase-I inhibition by GSNO. GSNO actually competes with GSH substrate-binding site of the enzyme.
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Affiliation(s)
- Rupam Sahoo
- Department of Biochemistry, University College of Science, Calcutta University, 35, Ballygunge Circular Road, Kolkata 700 019, India
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13
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Wei CC, Wang ZQ, Arvai AS, Hemann C, Hille R, Getzoff ED, Stuehr DJ. Structure of tetrahydrobiopterin tunes its electron transfer to the heme-dioxy intermediate in nitric oxide synthase. Biochemistry 2003; 42:1969-77. [PMID: 12590583 DOI: 10.1021/bi026898h] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
How 6R-tetrahydrobiopterin (H(4)B) participates in Arg hydroxylation as catalyzed by the nitric oxide synthases (NOSs) is a topic of current interest. Previous work with the oxygenase domain of inducible NOS (iNOSoxy) demonstrated that H(4)B radical formation is kinetically coupled to disappearance of an initial heme-dioxy intermediate and to Arg hydroxylation in a single turnover reaction run at 10 degrees C [Wei, C.-C., Wang, Z.-Q., Wang, Q., Meade, A. L., Hemann, C., Hille, R., and Stuehr, D. J. (2001) J. Biol. Chem. 276, 315-319]. Here we used 5-methyl-H(4)B to investigate how pterin structure influences radical formation and associated catalytic steps. In the presence of Arg, the heme-dioxy intermediate in 5-methyl-H(4)B-bound iNOSoxy reacted at a rate of 35 s(-)(1), which is 3-fold faster than with H(4)B. This was coupled to a faster rate of 5-methyl-H(4)B radical formation (40 vs 12.5 s(-)(1)) and to a faster and more productive Arg hydroxylation. The EPR spectrum of the enzyme-bound 5-methyl-H(4)B radical had different hyperfine structure than the bound H(4)B radical and exhibited a 3-fold longer half-life after its formation. A crystal structure of 5-methyl-H(4)B-bound iNOSoxy revealed that there are minimal changes in conformation of the bound pterin or in its interactions with the protein as compared to H(4)B. Together, we conclude the following: (1) The rate of heme-dioxy reduction is linked to pterin radical formation and is sensitive to pterin structure. (2) Faster heme-dioxy reduction increases the efficiency of Arg hydroxylation but still remains rate limiting for the reaction. (3) The 5-methyl group influences heme-dioxy reduction by altering the electronic properties of the pterin rather than changing protein structure or interactions. (4) Faster electron transfer from 5-methyl-H(4)B may be due to increased radical stability afforded by the N-5 methyl group.
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Affiliation(s)
- Chin-Chuan Wei
- Department of Immunology, The Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
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14
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Wang ZQ, Wei CC, Stuehr DJ. A conserved tryptophan 457 modulates the kinetics and extent of N-hydroxy-L-arginine oxidation by inducible nitric-oxide synthase. J Biol Chem 2002; 277:12830-7. [PMID: 11823464 DOI: 10.1074/jbc.m111967200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the oxygenase domain of mouse inducible nitric-oxide synthase (iNOSoxy), a conserved tryptophan residue, Trp-457, regulates the kinetics and extent of l-Arg oxidation to N(omega)-hydroxy-l-arginine (NOHA) by controlling electron transfer between bound (6R)-tetrahydrobiopterin (H(4)B) cofactor and the enzyme heme Fe(II)O(2) intermediate (Wang, Z. Q., Wei, C. C., Ghosh, S., Meade, A. L., Hemann, C., Hille, R., and Stuehr, D. J. (2001) Biochemistry 40, 12819-12825). To investigate whether NOHA oxidation to citrulline and nitric oxide (NO) is regulated by a similar mechanism, we performed single turnover reactions with wild type iNOSoxy and mutants W457F and W457A. Ferrous proteins containing NOHA plus H(4)B or NOHA plus 7,8-dihydrobiopterin (H(2)B), were mixed with O(2)-containing buffer, and then heme spectral transitions and product formation were followed versus time. All three proteins formed a Fe(II)O(2) intermediate with identical spectral characteristics. In wild type, H(4)B increased the disappearance rate of the Fe(II)O(2) intermediate relative to H(2)B, and its disappearance was coupled to the formation of a Fe(III)NO immediate product prior to formation of ferric enzyme. In W457F and W457A, the disappearance rate of the Fe(II)O(2) intermediate was slower than in wild type and took place without detectable build-up of the heme Fe(III)NO immediate product. Rates of Fe(II)O(2) disappearance correlated with rates of citrulline formation in all three proteins, and reactions containing H(4)B formed 1.0, 0.54, and 0.38 citrulline/heme in wild type, W457F, and W457A iNOSoxy, respectively. Thus, Trp-457 modulates the kinetics of NOHA oxidation by iNOSoxy, and this is important for determining the extent of citrulline and NO formation. Our findings support a redox role for H(4)B during NOHA oxidation to NO by iNOSoxy.
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Affiliation(s)
- Zhi-Qiang Wang
- Department of Immunology, Lerner Research Institute, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, Ohio 44195, USA
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Palumbo A, Astarita G, Picardo M, d'Ischia M. Ni(2+), a double-acting inhibitor of neuronal nitric oxide synthase interfering with L-arginine binding and Ca(2+)/calmodulin-dependent enzyme activation. Biochem Biophys Res Commun 2001; 285:142-6. [PMID: 11437384 DOI: 10.1006/bbrc.2001.5129] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ni(2+), a toxic and carcinogenic pollutant and one of the leading causes of contact dermatitis, is shown to inhibit neuronal nitric oxide synthase (nNOS) in a competitive, reversible manner with respect to the substrate l-arginine (K(i) = 30 +/- 4 microM). The IC(50) values were dependent on calmodulin (CaM) concentration, but proved independent of Ca(2+), tetrahydrobiopterin (BH(4)) and other essential cofactors. Ni(2+) also inhibited CaM-dependent cytochrome c reduction, NADPH oxidation, and H(2)O(2) production by nNOS. Overall, the action profile of Ni(2+) was suggestive of an unusual, double-acting inhibitor of nNOS affecting l-arginine-binding and Ca(2+)/CaM-dependent enzyme activation.
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Affiliation(s)
- A Palumbo
- Zoological Station "Anton Dohrn", Villa Comunale, Naples, I-80121, Italy.
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Palumbo A, d'Ischia M. Thiouracil antithyroid drugs as a new class of neuronal nitric oxide synthase inhibitors. Biochem Biophys Res Commun 2001; 282:793-7. [PMID: 11401533 DOI: 10.1006/bbrc.2001.4640] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Two established antithyroid drugs, 6-propyl-2-thiouracil and 6-methyl-2-thiouracil, as well as S-methylthiouracil, are shown to be competitive inhibitors of nitric oxide synthase (NOS) (K(I) values ranging from 14 to 60 microM), with moderate selectivity for the neuronal isoform. Other thioureylene and thioamide-containing heterocyclic systems proved virtually ineffective as NOS inhibitors. Besides offering novel useful leads for inhibitor design as well as to probe the active site of neuronal NOS, the results of this study may have interesting implications in relation to the antithyroid activity of thiouracils and their possible neurological effects.
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Affiliation(s)
- A Palumbo
- Zoological Station "Anton Dohrn,", Naples, Villa Comunale, I-80121, Italy.
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Wei CC, Wang ZQ, Wang Q, Meade AL, Hemann C, Hille R, Stuehr DJ. Rapid kinetic studies link tetrahydrobiopterin radical formation to heme-dioxy reduction and arginine hydroxylation in inducible nitric-oxide synthase. J Biol Chem 2001; 276:315-9. [PMID: 11020389 DOI: 10.1074/jbc.m008441200] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To understand how heme and (6R)-5,6,7,8-tetrahydro-l-biopterin (H(4)B) participate in nitric-oxide synthesis, we followed ferrous-dioxy heme (Fe(II)O(2)) formation and disappearance, H(4)B radical formation, and Arg hydroxylation during a single catalytic turnover by the inducible nitric-oxide synthase oxygenase domain (iNOSoxy). In all cases, prereduced (ferrous) enzyme was rapidly mixed with an O(2)-containing buffer to start the reaction. A ferrous-dioxy intermediate formed quickly (53 s(-1)) and then decayed with concurrent buildup of ferric iNOSoxy. The buildup of the ferrous-dioxy intermediate preceded both H(4)B radical formation and Arg hydroxylation. However, the rate of ferrous-dioxy decay (12 s(-1)) was equivalent to the rate of H(4)B radical formation (11 s(-1)) and the rate of Arg hydroxylation (9 s(-1)). Practically all bound H(4)B was oxidized to a radical during the reaction and was associated with hydroxylation of 0.6 mol of Arg/mol of heme. In dihydrobiopterin-containing iNOSoxy, ferrous-dioxy decay was much slower and was not associated with Arg hydroxylation. These results establish kinetic and quantitative links among ferrous-dioxy disappearance, H(4)B oxidation, and Arg hydroxylation and suggest a mechanism whereby H(4)B transfers an electron to the ferrous-dioxy intermediate to enable the formation of a heme-based oxidant that rapidly hydroxylates Arg.
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Affiliation(s)
- C C Wei
- Department of Immunology, The Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
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Palumbo A, d'Ischia M, Cioffi FA. 2-thiouracil is a selective inhibitor of neuronal nitric oxide synthase antagonising tetrahydrobiopterin-dependent enzyme activation and dimerisation. FEBS Lett 2000; 485:109-12. [PMID: 11094150 DOI: 10.1016/s0014-5793(00)02194-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
2-thiouracil (TU), an established antithyroid drug and melanoma-seeker, was found to selectively inhibit neuronal nitric oxide synthase (nNOS) in a competitive manner (K(i)=20 microM), being inactive on the other NOS isoforms. The drug apparently interfered with the substrate- and tetrahydrobiopterin (BH(4))-binding to the enzyme. It caused a 60% inhibition of H(2)O(2) production in the absence of L-arginine and BH(4), and antagonised BH(4)-induced dimerisation of nNOS, but did not affect cytochrome c reduction. These results open new perspectives in the understanding of the antithyroid action of TU and provide a new lead structure for the development of selective nNOS inhibitors to elucidate the interdependence of the substrate and pteridine sites and to modulate pathologically aberrant NO formation.
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Affiliation(s)
- A Palumbo
- Zoological Station Anton Dohrn, Naples, Italy.
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