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Jobson J, Tsegay PS, Beltran MT, Taher EA, Rein SR, Liu Y, Rein KS. Brevetoxin induces a shift in the redox state of the proteome and unfolded protein response in human lymphoblast cells that can be alleviated with the acrolein scavenger MESNA. Environ Toxicol Pharmacol 2023; 100:104137. [PMID: 37127110 DOI: 10.1016/j.etap.2023.104137] [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: 12/19/2022] [Revised: 04/24/2023] [Accepted: 04/29/2023] [Indexed: 05/03/2023]
Abstract
Human lymphoblast cells were treated with the marine algal toxin, brevetoxin-2 (PbTx-2), and its effects on the proteome were assessed by redox proteomics using cysteine reactive tandem mass tags (TMT). Additionally, cells were simultaneously treated with PbTx-2 and the antioxidant and acrolein scavenger sodium 2-mercaptoethylsulfonate (MESNA) to determine if MESNA could prevent the proteomic effects of brevetoxin-2. A massive shift in the redox state of the proteome of brevetoxin-2 treated cells was observed. The main pathway affected was genetic information processing. Significantly oxidized proteins included Trx-1, peroxyredoxins (Prxs), ribosomal proteins, and the eukaryotic initiation factor 2 β subunit (eIF2β). Proteins that were overexpressed in brevetoxin-treated cells included four folding chaperones. These effects were diminished in the presence of MESNA indicating that MESNA may act through its antioxidant properties or as a brevetoxin scavenger. These studies provide novel insights into new prophylactics for brevetoxicosis in humans and wildlife.
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Affiliation(s)
- Jordan Jobson
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Pawlos S Tsegay
- Biochemistry Ph.D. Program, Florida International University, Miami, FL 33199, USA
| | - Mayra Tabares Beltran
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Eman A Taher
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Samuel R Rein
- The School District of Philadelphia, Philadelphia, PA 19130, USA
| | - Yuan Liu
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; Biochemistry Ph.D. Program, Florida International University, Miami, FL 33199, USA; Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; Current address: The Water School, Department of Marine and Earth Science and Department of Chemistry and Physics, Florida Gulf Coast University, Fort Myers, FL 33965.
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Colon R, Wheater M, Joyce EJ, Ste Marie EJ, Hondal RJ, Rein KS. The Marine Neurotoxin Brevetoxin (PbTx-2) Inhibits Karenia brevis and Mammalian Thioredoxin Reductases by Targeting Different Residues. J Nat Prod 2021; 84:2961-2970. [PMID: 34752085 DOI: 10.1021/acs.jnatprod.1c00795] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The brevetoxins, neurotoxins produced by Karenia brevis, the Florida red tide dinoflagellate, effect fish and wildlife mortalities and adverse public health and economic impacts during recurrent blooms. Knowledge of the biochemical consequences of toxin production for K. brevis could provide insights into an endogenous role of the toxins, yet this aspect has not been thoroughly explored. In addition to neurotoxicity, the most abundant of the brevetoxins, PbTx-2, inhibits mammalian thioredoxin reductase (TrxR). The thioredoxin system, composed of the enzymes TrxR and thioredoxin (Trx), is present in all living organisms and is responsible in part for maintaining cellular redox homeostasis. Herein, we describe the cloning, expression, and semisynthesis of the selenoprotein TrxR from K. brevis (KbTrxR) and reductase activity toward a variety of substrates. Unlike mammalian TrxR, KbTrxR reduces oxidized glutathione (GSSG). We further demonstrate that PbTx-2 is an inhibitor of KbTrxR. Covalent adducts between KbTrxR and rat TrxR were detected by mass spectrometry. While both enzymes are adducted at or near the catalytic centers, the specific residues are distinct. Biochemical differences reported for high and low toxin producing strains of K. brevis are consistent with the inhibition of KbTrxR and suggest that PbTx-2 is an endogenous regulator of this critical enzyme.
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Affiliation(s)
- Ricardo Colon
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, Florida 33199, United States
| | - Michelle Wheater
- Department of Biochemistry, University of Vermont, 89 Beaumont Avenue, Given Building Room 413B, Burlington, Vermont 05405, United States
| | - Emily J Joyce
- Department of Biochemistry, University of Vermont, 89 Beaumont Avenue, Given Building Room 413B, Burlington, Vermont 05405, United States
| | - Emma J Ste Marie
- Department of Biochemistry, University of Vermont, 89 Beaumont Avenue, Given Building Room 413B, Burlington, Vermont 05405, United States
| | - Robert J Hondal
- Department of Biochemistry, University of Vermont, 89 Beaumont Avenue, Given Building Room 413B, Burlington, Vermont 05405, United States
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, Florida 33199, United States
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Colon R, Rein KS. Essential components of the xanthophyll cycle differ in high and low toxin Karenia brevis. Harmful Algae 2021; 103:102006. [PMID: 33980446 PMCID: PMC10246377 DOI: 10.1016/j.hal.2021.102006] [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] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 02/26/2021] [Accepted: 02/27/2021] [Indexed: 06/09/2023]
Abstract
The dinoflagellate Karenia brevis, blooms annually in the Gulf of Mexico, producing a suite of neurotoxins known as the brevetoxins. The cellular toxin content of K. brevis, however, is highly variable between or even within strains. Herein, we investigate physiological differences between high (KbHT) and low (KbLT) toxin producing cultures both derived from the Wilson strain, related to energy-dependent quenching (qE) by photosystem II, and reduced thiol content of the proteome. We demonstrate that gene and protein expression of the xanthophyll cycle enzyme diadinoxanthin de-epoxidase (Dde) and monogalactosyldiacylglycerol (MGDG) synthase are not significantly different in the two cultures. Using redox proteomics, we report a significantly higher reduced cysteine content in the low toxin proteome, including plastid localized thioredoxin reductase (Trx) which can result in inactivation of Dde and activation of MGDG synthase. We also report significant differences in the lipidomes of KbHT and KbLT with respect to MGDG, which facilitates the xanthophyll cycle.
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Affiliation(s)
- Ricardo Colon
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States.
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Abstract
Abstract
Antiserum against PbTx-2-type brevetoxins was produced by immunizing rabbits with a PbTx-2–bovine serum albumin (BSA) conjugate. This serum had a higher affinity, but lower titer, than our current goat serum. Using 4 natural brevetoxins and 6 synthetic derivatives as competitors in our brevetoxin radioimmunoassay, we determined the epitope specificity of both sera. Modification of the backbone structure at C-42 on the K-ring had little or no effect on the antigen-binding capability of either serum. Reduction of the double bond between C-2 and C-3 on the A-ring by reduction of the lactone decreased binding 500 to 750-fold. Epoxidation of the double bond between C-27 and C-28 on the H-ring did not affect binding, which suggested that the goat serum is specific for the A-ring region of the brevetoxin backbone. In contrast, modifying the A-ring had no effect on rabbit serum binding. However, epoxidation of the H-ring decreased binding 5 to 20-fold, which suggested that the rabbit antiserum is specific for the H-ring region of the molecule. These results suggest that assays utilizing only one antibody may not adequately detect toxin metabolites if molecules are altered in the critical region of antibody recognition.
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Affiliation(s)
- Mark A Poli
- U.S. Army Medical Research Institute of Infectious Diseases, Fort Derrick, Frederick, MD 21702-5011
| | - Kathleen S Rein
- National Institute of Environmental Health Sciences, Marine and Freshwater Biomedical Sciences Center, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, FL 33101
| | - Daniel G Baden
- National Institute of Environmental Health Sciences, Marine and Freshwater Biomedical Sciences Center, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, FL 33101
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Baden DG, Melinek R, Sechet V, Trainer VL, Schultz DR, Rein KS, Tomas CR, Delgado J, Hale L. Modified Immunoassays for Polyether Toxins: Implications of Biological Matrixes, Metabolic States, and Epitope Recognition. J AOAC Int 2020. [DOI: 10.1093/jaoac/78.2.499] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Polyether marine toxins are responsible for the seafood intoxication phenomena known as neurotoxic shellfish poisoning (due to brevetoxins), ciguatera (due to ciguatoxin), and diarrheic shellfish poisoning (due to okadaic acid). Using traditional techniques of hapten (pure toxin) conjugation to protein to create complete antigen, animal immunization and antibody isolation, and specific antibody subpopulation purification, discriminating antibodies have been isolated that detect brevetoxins and ciguatoxin, but not okadaic acid, in a dose-dependent fashion. Using microorganic chemistry and purified toxins, a unique set of tools has been created for the study of polyether ladder toxin accumulation; depuration; and specific site localization in tissues, food sources, and clinical samples. Developed test protocols can detect toxin in dinoflagellate cells, in extracts from food sources, in seawater and culture media, and in human serum samples. Enzyme-linked immunosorbent assay protocols developed for eventual collaborative testing have been successful in limited applications within the laboratory (correlation coefficient of 0.92 excluding 2 outliers), and alternative formats are being developed to optimize the basic test for use in research laboratories, regulatory laboratories, and field inspections.
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Affiliation(s)
- Daniel G Baden
- NIEHS Marine and Freshwater Biomedical Sciences Center, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149
| | - Rosemary Melinek
- NIEHS Marine and Freshwater Biomedical Sciences Center, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149
| | - Veronique Sechet
- NIEHS Marine and Freshwater Biomedical Sciences Center, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149
| | - Vera L Trainer
- NIEHS Marine and Freshwater Biomedical Sciences Center, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149
| | - Duane R Schultz
- NIEHS Marine and Freshwater Biomedical Sciences Center, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149
| | - Kathleen S Rein
- NIEHS Marine and Freshwater Biomedical Sciences Center, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149
| | - Carmelo R Tomas
- NIEHS Marine and Freshwater Biomedical Sciences Center, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149
| | - Jesus Delgado
- NIEHS Marine and Freshwater Biomedical Sciences Center, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149
| | - Lauren Hale
- NIEHS Marine and Freshwater Biomedical Sciences Center, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149
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Tuladhar A, Hondal RJ, Colon R, Hernandez EL, Rein KS. Effectors of thioredoxin reductase: Brevetoxins and manumycin-A. Comp Biochem Physiol C Toxicol Pharmacol 2019; 217:76-86. [PMID: 30476593 PMCID: PMC7485175 DOI: 10.1016/j.cbpc.2018.11.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 11/21/2018] [Indexed: 02/03/2023]
Abstract
The activities of two effectors, brevetoxin (PbTx) and manumycin-A (Man-A), of thioredoxin reductase (TrxR) have been evaluated against a series of fourteen TrxR orthologs originating from mammals, insects and protists and several mutants. Man-A, a molecule with numerous electrophilic sites, forms a covalent adduct with most selenocystine (Sec)-containing TrxR enzymes. The evidence also demonstrates that Man-A can form covalent adducts with some non-Sec-containing enzymes. The activities of TrxR enzymes towards various substrates are moderated by Man-A either positively or negatively depending on the enzyme. In general, the reduction of substrates by Sec-containing TrxR is inhibited and NADPH oxidase activity is activated. For non-Sec-containing TrxR the effect of Man-A on the reduction of substrates is variable, but NADPH oxidase activity can be activated even in the absence of covalent modification of TrxR. The effect of PbTx is less pronounced. A smaller subset of enzymes is affected by PbTx. With a single exception, the activities of most of this subset are activated. Although both PbTx variants can react with selenocysteine, a stable covalent adduct is not formed with any of the TrxR enzymes. The key findings from this work are (i) the identification of an alternate mechanism of toxicity for the algal toxin brevetoxin (ii) the demonstration that covalent modification of TrxR is not a prerequisite for the activation of NADPH oxidase activity of TrxR and (iii) the identification of an inhibitor which can discriminate between cytosolic and mitochondrial TrxR.
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Affiliation(s)
- Anupama Tuladhar
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Robert J Hondal
- Department of Biochemistry, 89 Beaumont Ave, Given Building Room 413B, Burlington, VT 05405, United States
| | - Ricardo Colon
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Elyssa L Hernandez
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States.
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Tuladhar A, Rein KS. Manumycin A Is a Potent Inhibitor of Mammalian Thioredoxin Reductase-1 (TrxR-1). ACS Med Chem Lett 2018; 9:318-322. [PMID: 29670693 DOI: 10.1021/acsmedchemlett.7b00489] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/05/2018] [Indexed: 12/15/2022] Open
Abstract
The anticancer effect of manumycin A (Man A) has been attributed to the inhibition of farnesyl transferase (FTase), an enzyme that is responsible for post-translational modification of Ras proteins. However, we have discovered that Man A inhibits mammalian cytosolic thioredoxin reductase 1 (TrxR-1) in a time-dependent manner, with an IC50 of 272 nM with preincubation and 1586 nM without preincubation. The inhibition of TrxR-1 by Man A is irreversible and is the result of a covalent interaction between Man A and TrxR-1. Evidence presented herein demonstrates that Man A forms a Michael adduct with the selenocysteine residue, which is located in the C-terminal redox center of TrxR-1. Inhibitors of TrxR-1, which act through this mechanism, convert TrxR-1 into a SecTRAP, which utilizes NADPH to reduce oxygen to superoxide radical anion (O2-•).
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Affiliation(s)
- Anupama Tuladhar
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW Eighth Street, Miami, Florida 33199, United States
| | - Kathleen S. Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW Eighth Street, Miami, Florida 33199, United States
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Chen W, Colon R, Louda JW, Del Rey FR, Durham M, Rein KS. Brevetoxin (PbTx-2) influences the redox status and NPQ of Karenia brevis by way of thioredoxin reductase. Harmful Algae 2018; 71:29-39. [PMID: 29306394 PMCID: PMC5994908 DOI: 10.1016/j.hal.2017.11.004] [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] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Revised: 11/18/2017] [Accepted: 11/18/2017] [Indexed: 06/07/2023]
Abstract
The Florida red tide dinoflagellate, Karenia brevis, is the major harmful algal bloom dinoflagellate of the Gulf of Mexico and plays a destructive role in the region. Blooms of K. brevis can produce brevetoxins: ladder-shaped polyether (LSP) compounds, which can lead to adverse human health effects, such as reduced respiratory function through inhalation exposure, or neurotoxic shellfish poisoning through consumption of contaminated shellfish. The endogenous role of the brevetoxins remains uncertain. Recent work has shown that some forms of NADPH dependent thioredoxin reductase (NTR) are inhibited by brevetoxin-2 (PbTx-2). The study presented herein reveals that high toxin and low toxin K. brevis, which have a ten-fold difference in toxin content, also show a significant difference in their ability, not only to produce brevetoxin, but also in their cellular redox status and distribution of xanthophyll cycle pigments. These differences are likely due to the inhibition of NTR by brevetoxin. The work could shed light on the physiological role that brevetoxin fills for K. brevis.
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Affiliation(s)
- Wei Chen
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8thStreet, Miami, FL 33199, United States.
| | - Ricardo Colon
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8thStreet, Miami, FL 33199, United States.
| | - J William Louda
- Department of Chemistry and Biochemistry, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431 United States.
| | - Freddy Rodriguez Del Rey
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8thStreet, Miami, FL 33199, United States.
| | - Michaella Durham
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8thStreet, Miami, FL 33199, United States.
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8thStreet, Miami, FL 33199, United States.
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Chen W, Tuladhar A, Rolle S, Lai Y, Rodriguez Del Rey F, Zavala CE, Liu Y, Rein KS. Brevetoxin-2, is a unique inhibitor of the C-terminal redox center of mammalian thioredoxin reductase-1. Toxicol Appl Pharmacol 2017; 329:58-66. [PMID: 28551108 DOI: 10.1016/j.taap.2017.05.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [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: 03/22/2017] [Revised: 05/15/2017] [Accepted: 05/22/2017] [Indexed: 11/15/2022]
Abstract
Karenia brevis, the Florida red tide dinoflagellate produces a suite of neurotoxins known as the brevetoxins. The most abundant of the brevetoxins PbTx-2, was found to inhibit the thioredoxin-thioredoxin reductase system, whereas the PbTx-3 has no effect on this system. On the other hand, PbTx-2 activates the reduction of small disulfides such as 5,5'-dithio-bis-(2-nitrobenzoic acid) by thioredoxin reductase. PbTx-2 has an α, β-unsaturated aldehyde moiety which functions as an efficient electrophile and selenocysteine conjugates are readily formed. PbTx-2 blocks the inhibition of TrxR by the inhibitor curcumin, whereas curcumin blocks PbTx-2 activation of TrxR. It is proposed that the mechanism of inhibition of thioredoxin reduction is via the formation of a Michael adduct between selenocysteine and the α, β-unsaturated aldehyde moiety of PbTx-2. PbTx-2 had no effect on the rates of reactions catalyzed by related enzymes such as glutathione reductase, glutathione peroxidase or glutaredoxin.
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Affiliation(s)
- Wei Chen
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Anupama Tuladhar
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Shantelle Rolle
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Yanhao Lai
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Freddy Rodriguez Del Rey
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Cristian E Zavala
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Yuan Liu
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States; Biomolecular Sciences Institute, School of Integrated Sciences and Humanity, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States.
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Sun P, Leeson C, Zhi X, Leng F, Pierce RH, Henry MS, Rein KS. Characterization of an epoxide hydrolase from the Florida red tide dinoflagellate, Karenia brevis. Phytochemistry 2016; 122:11-21. [PMID: 26626160 PMCID: PMC4724521 DOI: 10.1016/j.phytochem.2015.11.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Revised: 10/19/2015] [Accepted: 11/05/2015] [Indexed: 05/11/2023]
Abstract
Epoxide hydrolases (EH, EC 3.3.2.3) have been proposed to be key enzymes in the biosynthesis of polyether (PE) ladder compounds such as the brevetoxins which are produced by the dinoflagellate Karenia brevis. These enzymes have the potential to catalyze kinetically disfavored endo-tet cyclization reactions. Data mining of K. brevis transcriptome libraries revealed two classes of epoxide hydrolases: microsomal and leukotriene A4 (LTA4) hydrolases. A microsomal EH was cloned and expressed for characterization. The enzyme is a monomeric protein with molecular weight 44kDa. Kinetic parameters were evaluated using a variety of epoxide substrates to assess substrate selectivity and enantioselectivity, as well as its potential to catalyze the critical endo-tet cyclization of epoxy alcohols. Monitoring of EH activity in high and low toxin producing cultures of K. brevis over a three week period showed consistently higher activity in the high toxin producing culture implicating the involvement of one or more EH in brevetoxin biosynthesis.
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Affiliation(s)
- Pengfei Sun
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
| | - Cristian Leeson
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Xiaoduo Zhi
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Fenfei Leng
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
| | - Richard H Pierce
- Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL 34236, USA.
| | - Michael S Henry
- Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL 34236, USA.
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
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Cassell RT, Chen W, Thomas S, Liu L, Rein KS. Brevetoxin, the Dinoflagellate Neurotoxin, Localizes to Thylakoid Membranes and Interacts with the Light-Harvesting Complex II (LHCII) of Photosystem II. Chembiochem 2015; 16:1060-7. [DOI: 10.1002/cbic.201402669] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Indexed: 11/11/2022]
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Van Dolah FM, Zippay ML, Pezzolesi L, Rein KS, Johnson JG, Morey JS, Wang Z, Pistocchi R. Subcellular localization of dinoflagellate polyketide synthases and fatty acid synthase activity. J Phycol 2013; 49:1118-1127. [PMID: 27007632 DOI: 10.1111/jpy.12120] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 08/25/2013] [Indexed: 06/05/2023]
Abstract
Dinoflagellates are prolific producers of polyketide secondary metabolites. Dinoflagellate polyketide synthases (PKSs) have sequence similarity to Type I PKSs, megasynthases that encode all catalytic domains on a single polypeptide. However, in dinoflagellate PKSs identified to date, each catalytic domain resides on a separate transcript, suggesting multiprotein complexes similar to Type II PKSs. Here, we provide evidence through coimmunoprecipitation that single-domain ketosynthase and ketoreductase proteins interact, suggesting a predicted multiprotein complex. In Karenia brevis (C.C. Davis) Gert Hansen & Ø. Moestrup, previously observed chloroplast localization of PKSs suggested that brevetoxin biosynthesis may take place in the chloroplast. Here, we report that PKSs are present in both cytosol and chloroplast. Furthermore, brevetoxin is not present in isolated chloroplasts, raising the question of what chloroplast-localized PKS enzymes might be doing. Antibodies to K. brevis PKSs recognize cytosolic and chloroplast proteins in Ostreopsis cf. ovata Fukuyo, and Coolia monotis Meunier, which produce different suites of polyketide toxins, suggesting that these PKSs may share common pathways. Since PKSs are closely related to fatty acid synthases (FAS), we sought to determine if fatty acid biosynthesis colocalizes with either chloroplast or cytosolic PKSs. [(3) H]acetate labeling showed fatty acids are synthesized in the cytosol, with little incorporation in chloroplasts, consistent with a Type I FAS system. However, although 29 sequences in a K. brevis expressed sequence tag database have similarity (BLASTx e-value <10(-10) ) to PKSs, no transcripts for either Type I (cytosolic) or Type II (chloroplast) FAS are present. Further characterization of the FAS complexes may help to elucidate the functions of the PKS enzymes identified in dinoflagellates.
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Affiliation(s)
- Frances M Van Dolah
- Marine Biotoxins Program, NOAA Center for Coastal Environmental Health and Biomolecular Research, Charleston, South Carolina, 29412, USA
- Marine Biomedical and Environmental Sciences, Medical University of South Carolina, Charleston, South Carolina, 29412, USA
| | - Mackenzie L Zippay
- Marine Biotoxins Program, NOAA Center for Coastal Environmental Health and Biomolecular Research, Charleston, South Carolina, 29412, USA
- Marine Biomedical and Environmental Sciences, Medical University of South Carolina, Charleston, South Carolina, 29412, USA
| | - Laura Pezzolesi
- Interdepartmental Research Centre for Environmental Science (CIRSA), University of Bologna, Ravenna, 48123, Italy
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, 33199, USA
| | - Jillian G Johnson
- Marine Biotoxins Program, NOAA Center for Coastal Environmental Health and Biomolecular Research, Charleston, South Carolina, 29412, USA
- Marine Biomedical and Environmental Sciences, Medical University of South Carolina, Charleston, South Carolina, 29412, USA
| | - Jeanine S Morey
- Marine Biotoxins Program, NOAA Center for Coastal Environmental Health and Biomolecular Research, Charleston, South Carolina, 29412, USA
| | - Zhihong Wang
- Marine Biotoxins Program, NOAA Center for Coastal Environmental Health and Biomolecular Research, Charleston, South Carolina, 29412, USA
| | - Rossella Pistocchi
- Interdepartmental Research Centre for Environmental Science (CIRSA), University of Bologna, Ravenna, 48123, Italy
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Wang W, Simovic DD, Di M, Fieber L, Rein KS. Synthesis, receptor binding and activity of iso and azakainoids. Bioorg Med Chem Lett 2013; 23:1949-52. [PMID: 23481645 DOI: 10.1016/j.bmcl.2013.02.046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 02/05/2013] [Accepted: 02/08/2013] [Indexed: 11/26/2022]
Abstract
Two syntheses for the production of an unsubstituted azakainoid are described. The 1,3-dipolar cycloaddition of diazomethane with trans-dibenzyl glutaconate yields a 1-pyrazoline, which may be reduced directly to the pyrazolidine. An unexpected trans-cis isomerization is observed during Hg/Al reduction of the 1-pyrazoline NN bond. Alternatively, when TMS diazomethane is used as the dipole, the resulting 2-pyrazoline obtained after desilylation may be reduced with NaCNBH3 to provide the trans azakainate analog exclusively. The synthesis of an unsubstituted isokainoid via Michael addition is also described. Glutamate receptor binding assays revealed that the azakaniod has a moderate affinity for unspecified glutamate receptors. Membrane depolarization of Aplysia neurons upon application of the azakainoid demonstrates that it is an ionotropic glutamate receptor agonist.
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Affiliation(s)
- Wentian Wang
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Str., Miami, FL 33199, USA
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15
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Wang W, Cassell RT, Rein KS. The use of Mosher derivatives for the determination of the absolute configuration of substituted isoxazolidines. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/j.tetasy.2013.01.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Abstract
Pahayokolides A-B are cyanobacteria derived non-ribosomal peptides which exhibit cytotoxicity against a number of cancer cell lines. The biosynthetic origin of the 3-amino-2,5,7,8-tetrahydroxy-10-methylundecanoic acid (Athmu) moiety has been investigated using stable isotope incorporation experiments. While α-ketoisocaproic acid (α-KIC), α-hydroxyisocaproic acid (α-HIC) and leucine all serve as precursors to Athmu, the feeding of [1-(13)C] α-KIC results in more than threefold greater (13)C enrichment than the other precursors. This result suggests that α-KIC is the immediate precursor which is selected and activated by the adenylation domain of the loading NRPS module and subsequently reduced in a fashion similar to that of the recently identified pathways for cryptophycins A-B, cereulide and valinomycin.
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Affiliation(s)
- Li Liu
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
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17
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Liu L, Guo F, Crain S, Quilliam MA, Wang X, Rein KS. The structures of three metabolites of the algal hepatotoxin okadaic acid produced by oxidation with human cytochrome P450. Bioorg Med Chem 2012; 20:3742-5. [PMID: 22608922 DOI: 10.1016/j.bmc.2012.04.046] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 04/16/2012] [Accepted: 04/24/2012] [Indexed: 11/25/2022]
Abstract
Four metabolites of okadaic acid were generated by incubation with human recombinant cytochrome P450 3A4. The structures of two of the four metabolites have been determined by MS/MS experiments and 1D and 2D NMR methods using 94 and 133 μg of each metabolite. The structure of a third metabolite was determined by oxidation to a metabolite of known structure. Like okadaic acid, the metabolites are inhibitors of protein phosphatase PP2A. Although one of the metabolites does have an α,β unsaturated carbonyl with the potential to form adducts with an active site cysteine, all of the metabolites are reversible inhibitors of PP2A.
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Affiliation(s)
- Li Liu
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, USA
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18
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Fieber LA, Greer JB, Guo F, Crawford DC, Rein KS. GENE EXPRESSION PROFILING OF HUMAN LIVER CARCINOMA (HepG2) CELLS EXPOSED TO THE MARINE TOXIN OKADAIC ACID. Toxicol Environ Chem 2012; 24:1805-1821. [PMID: 23172983 PMCID: PMC3500632 DOI: 10.1080/02772248.2012.730199] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The marine toxin, okadaic acid (OA) is produced by dinoflagellates of the genera Prorocentrum and Dinophysis and is the causative agent of the syndrome known as diarrheic shellfish poisoning (DSP). In addition, OA acts as both a tumor promoter, attributed to OA-induced inhibition of protein phosphatases as well as an inducer of apoptosis. To better understand the potentially divergent toxicological profile of OA, the concentration dependent cytotoxicity and alterations in gene expression on the human liver tumor cell line HepG2 upon OA exposure were determined using RNA microarrays, DNA fragmentation, and cell proliferation assays as well as determinations of cell detachment and cell death in different concentrations of OA. mRNA expression was quantified for approximately 15,000 genes. Cell attachment and proliferation were both negatively correlated with OA concentration. Detached cells displayed necrotic DNA signatures but apoptosis also was broadly observed. Data suggest that OA has a concentration dependent effect on cell cycle, which might explain the divergent effects that at low concentration OA stimulates genes involved in the cell cycle and at high concentrations it stimulates apoptosis.
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Affiliation(s)
- Lynne A. Fieber
- Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Cswy, Miami, FL, USA 33149
| | - Justin B. Greer
- Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Cswy, Miami, FL, USA 33149
| | - Fujiang Guo
- Department of Chemistry and Biochemistry, 11200 SW 8 St, Florida International University, Miami, FL, USA33199
| | - Douglas C. Crawford
- Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Cswy, Miami, FL, USA 33149
| | - Kathleen S. Rein
- Department of Chemistry and Biochemistry, 11200 SW 8 St, Florida International University, Miami, FL, USA33199
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19
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Liu L, Bearden DW, Rein KS. Biosynthetic origin of the 3-amino-2,5,7,8-tetrahydroxy-10-methylundecanoic acid moiety and absolute configuration of pahayokolides A and B. J Nat Prod 2011; 74:1535-8. [PMID: 21650153 PMCID: PMC3163906 DOI: 10.1021/np200362q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Pahayokolides A and B are cyclic undecapeptides that were isolated from the cyanobacterium Lyngbya sp. They contain the unusual α-hydroxy-β-amino acid 3-amino-2,5,7,8-tetrahydroxy-10-methylundecanoic acid (Athmu). The absolute configurations of the amino acids of the pahayokolides, except for the four oxygen-bearing stereocenters of Athmu, have been determined by Marphy's method. Incorporation of labeled leucine and acetate precursors into the pahayokolides has established that Athmu is derived from a leucine or α-keto isocaproic acid starter unit, which is further extended with three acetate units.
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Affiliation(s)
- Li Liu
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Daniel W. Bearden
- Analytical Chemistry Division, National Institute of Standards and Technology, Hollings Marine Laboratory, Charleston, South Carolina 29412
| | - Kathleen S. Rein
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
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Shetty KG, Huntzicker JV, Rein KS, Jayachandran K. Biodegradation of polyether algal toxins--isolation of potential marine bacteria. J Environ Sci Health A Tox Hazard Subst Environ Eng 2010; 45:1850-1857. [PMID: 20954040 PMCID: PMC3516395 DOI: 10.1080/10934529.2010.520510] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Marine algal toxins such as brevetoxins, okadaic acid, yessotoxin, and ciguatoxin are polyether compounds. The fate of polyether toxins in the aqueous phase, particularly bacterial biotransformation of the toxins, is poorly understood. An inexpensive and easily available polyether structural analog salinomycin was used for enrichment and isolation of potential polyether toxin degrading aquatic marine bacteria from Florida bay area, and from red tide endemic sites in the South Florida Gulf coast. Bacterial growth on salinomycin was observed in most of the enrichment cultures from both regions with colony forming units ranging from 0 to 6×10(7) per mL. The salinomycin biodegradation efficiency of bacterial isolates determined using LC-MS ranged from 22% to 94%. Selected bacterial isolates were grown in media with brevetoxin as the sole carbon source to screen for brevetoxin biodegradation capability using ELISA. Out of the two efficient salinomycin biodegrading isolates MB-2 and MB-4, maximum brevetoxin biodegradation efficiency of 45% was observed with MB-4, while MB-2 was unable to biodegrade brevetoxin. Based on 16S rRNA sequence similarity MB-4 was found have a match with Chromohalobacter sp.
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Affiliation(s)
- Kateel G Shetty
- Department of Earth and Environment, Florida International University, Miami, Florida 33199-0001, USA
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An T, Winshell J, Scorzetti G, Fell JW, Rein KS. Identification of okadaic acid production in the marine dinoflagellate Prorocentrum rhathymum from Florida Bay. Toxicon 2010; 55:653-7. [PMID: 19735671 PMCID: PMC2813983 DOI: 10.1016/j.toxicon.2009.08.018] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [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: 02/10/2009] [Revised: 08/20/2009] [Accepted: 08/20/2009] [Indexed: 11/17/2022]
Abstract
Extracts of fifty-seven newly isolated strains of dinoflagellates and raphidophytes were screened for protein phosphatase (PP2A) inhibition. Five strains, identified by rDNA sequence analysis as Prorocentrum rhathymum, tested positive and the presence of okadaic acid was confirmed in one strain by HPLC-MS/MS and by HPLC with fluorescence detection and HPLC-MS of the okadaic acid ADAM derivative. Quantitation of the ADAM derivative indicated that the concentration of okadaic acid in the culture medium is 0.153 microg/L.
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Affiliation(s)
- Tianying An
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8St., Miami, FL 33199, USA
- Center for Oceans and Human Health, University of Miami, 4600 Rickenbacker Cswy, Miami, FL 33149, USA
| | - Jamie Winshell
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8St., Miami, FL 33199, USA
- Center for Oceans and Human Health, University of Miami, 4600 Rickenbacker Cswy, Miami, FL 33149, USA
| | - Gloria Scorzetti
- Center for Oceans and Human Health, University of Miami, 4600 Rickenbacker Cswy, Miami, FL 33149, USA
- Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Cswy, Miami, FL 33149, USA
| | - Jack W. Fell
- Center for Oceans and Human Health, University of Miami, 4600 Rickenbacker Cswy, Miami, FL 33149, USA
- Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Cswy, Miami, FL 33149, USA
| | - Kathleen S. Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8St., Miami, FL 33199, USA
- Center for Oceans and Human Health, University of Miami, 4600 Rickenbacker Cswy, Miami, FL 33149, USA
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22
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Guo F, An T, Rein KS. The algal hepatoxoxin okadaic acid is a substrate for human cytochromes CYP3A4 and CYP3A5. Toxicon 2009; 55:325-32. [PMID: 19699225 DOI: 10.1016/j.toxicon.2009.08.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Revised: 08/11/2009] [Accepted: 08/14/2009] [Indexed: 11/28/2022]
Abstract
The hepatotoxin okadaic acid (OA) was incubated with nine human recombinant cytochrome P450s (1A1, 1A2, 2C8, 2C9, 2C19, 2D6, 2E1, 3A4 and 3A5). Both CYP3A4 and CYP3A5 converted OA to a mixture of the same four metabolites, but incubation with CYP3A4 resulted in higher levels of conversion. Michaelis-Menten parameters, K(m) (73.4 microM) and V(max) (7.23 nmol of metabolitesnmol(-1)min(-1)) for CYP3A4 were calculated by analyzing double-reciprocal plots. LC-MS(n) analysis and chemical interconversion indicate that metabolites 2 and 3 are the 11S-hydroxy and 11R-hydroxy okadaic acid respectively, while metabolite 4 is 11-oxo okadaic acid. LC-MS(n) analysis of metabolite 1 shows a molecular ion which corresponds to an addition of 16 amu to OA, also suggesting hydroxylation, but the specific site has not been identified. The same four metabolites were produced upon incubation of okadaic acid with pooled human liver microsomes. This transformation could be completely inhibited with ketokonazole, and inhibitor of the CYP3A family of enzymes. The metabolites were determined to be only slightly less potent inhibitors of serine threonine protein phosphatase 2A (PP2A) when compared to OA. As PP2A is the principle molecular target for OA, these oxidative transformations may not effectively detoxify OA.
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Affiliation(s)
- Fujiang Guo
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th St., Miami, FL 33199, USA
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23
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Sinigalliano CD, Winshell J, Guerrero MA, Scorzetti G, Fell JW, Eaton RW, Brand L, Rein KS. Viable cell sorting of dinoflagellates by multiparametric flow cytometry. Phycologia 2009; 48:249-257. [PMID: 20305733 PMCID: PMC2841404 DOI: 10.2216/08-51.1] [Citation(s) in RCA: 19] [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] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Electronic cell sorting for isolation and culture of dinoflagellates and other marine eukaryotic phytoplankton was compared to the traditional method of manually picking cells using a micropipette. Trauma to electronically sorted cells was not a limiting factor, as fragile dinoflagellates, such as Karenia brevis (Dinophyceae), survived electronic cell sorting to yield viable cells. The rate of successful isolation of large-scale (> 4 litres) cultures was higher for manual picking than for electronic cell sorting (2% vs 0.5%, respectively). However, manual picking of cells is more labor intensive and time consuming. Most manually isolated cells required repicking, as the cultures were determined not to be unialgal after a single round of isolation; whereas, no cultures obtained in this study from electronic single-cell sorting required resorting. A broad flow cytometric gating logic was employed to enhance species diversity. The percentages of unique genotypes produced by manual picking or electronic cell sorting were similar (57% vs 54%, respectively), and each approach produced a variety of dinoflagellate or raphidophyte genera. Alternatively, a highly restrictive gating logic was successfully used to target K. brevis from a natural bloom sample. Direct electronic single-cell sorting was more successful than utilizing a pre-enrichment sort followed by electronic single-cell sorting. The appropriate recovery medium may enhance the rate of successful isolations. Seventy percent of isolated cells were recovered in a new medium (RE) reported here, which was optimized for axenic dinoflagellate cultures. The greatest limiting factor to the throughput of electronic cell sorting is the need for manual postsort culture maintenance and assessment of the large number of isolated cells. However, when combined with newly developed automated methods for growth screening, electronic single-cell sorting has the potential to accelerate the discovery of new algal strains.
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Affiliation(s)
- Christopher D. Sinigalliano
- Southeast Environmental Research Center, Florida International University, Miami, FL 33199, USA
- Cooperative Institute for Marine and Atmospheric Studies, RSMAS, University of Miami, Miami, FL 33149, USA
- NOAA Atlantic Oceanographic and Meteorological Laboratory, Miami, FL 33149, USA
| | - Jamie Winshell
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Maria A. Guerrero
- Southeast Environmental Research Center, Florida International University, Miami, FL 33199, USA
| | - Gloria Scorzetti
- Division of Marine Biology and Fisheries, RSMAS, University of Miami, Miami, FL 33149, USA
| | - Jack W. Fell
- Division of Marine Biology and Fisheries, RSMAS, University of Miami, Miami, FL 33149, USA
| | - Richard W. Eaton
- Southern Regional Research Center, ARS USDA, New Orleans, LA 70124, USA
| | - Larry Brand
- Division of Marine Biology and Fisheries, RSMAS, University of Miami, Miami, FL 33149, USA
| | - Kathleen S. Rein
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
- Corresponding author ()
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Perez R, Liu L, Lopez J, An T, Rein KS. Diverse bacterial PKS sequences derived from okadaic acid-producing dinoflagellates. Mar Drugs 2008; 6:164-79. [PMID: 18728765 PMCID: PMC2525486 DOI: 10.3390/md20080009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 05/09/2008] [Accepted: 05/13/2008] [Indexed: 11/16/2022] Open
Abstract
Okadaic acid (OA) and the related dinophysistoxins are isolated from dinoflagellates of the genus Prorocentrum and Dinophysis. Bacteria of the Roseobacter group have been associated with okadaic acid producing dinoflagellates and have been previously implicated in OA production. Analysis of 16S rRNA libraries reveals that Roseobacter are the most abundant bacteria associated with OA producing dinoflagellates of the genus Prorocentrum and are not found in association with non-toxic dinoflagellates. While some polyketide synthase (PKS) genes form a highly supported Prorocentrum clade, most appear to be bacterial, but unrelated to Roseobacter or Alpha-Proteobacterial PKSs or those derived from other Alveolates Karenia brevis or Crytosporidium parvum.
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Affiliation(s)
- Roberto Perez
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
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25
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Gantar M, Berry JP, Thomas S, Wang M, Perez R, Rein KS. Allelopathic activity among Cyanobacteria and microalgae isolated from Florida freshwater habitats. FEMS Microbiol Ecol 2008; 64:55-64. [PMID: 18266743 DOI: 10.1111/j.1574-6941.2008.00439.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [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] Open
Abstract
We evaluated allelopathic interactions between strains of Cyanobacteria and green algae isolated from south and central Florida. Allelopathy, including inhibition or stimulation of growth, was assessed by cocultivation of each of the isolated strains, as well as by evaluation of extracts prepared from the isolates. All of the strains of Cyanobacteria, and four of the six isolates of green algae, showed some allelopathic activity (i.e. inhibition or stimulation of the growth of other strains). Of these, the most pronounced activity was observed for the cyanobacterial isolate Fischerella sp. strain 52-1. In the cocultivation experiments this cyanobacterium inhibited the growth of all tested green algae and Cyanobacteria. The crude lipophilic extracts from Fischerella sp. strain 52-1 isolated from both the biomass and the culture liquid inhibited photosynthesis of the green alga Chlamydomonas sp. in a concentration- and time-dependent manner and caused extensive loss of ultrastructural cell organization. Preliminary chemical characterization of compounds extracted from Fischerella sp. strain 52-1 indicated the presence of indole alkaloids, and further characterization has confirmed that these compounds belong to the hapalindoles previously isolated from other species of Fischerella and related genera. Further chemical characterization of these compounds, and further investigation of their apparent role in allelopathy is ongoing.
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Affiliation(s)
- Miroslav Gantar
- Department of Biological Sciences, Florida International University, Miami, FL 33199, USA.
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An T, Kumar TKS, Wang M, Liu L, Lay JO, Liyanage R, Berry J, Gantar M, Marks V, Gawley RE, Rein KS. Structures of pahayokolides A and B, cyclic peptides from a Lyngbya sp. J Nat Prod 2007; 70:730-5. [PMID: 17432902 PMCID: PMC2573040 DOI: 10.1021/np060389p] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The isolation and structure elucidation of two cyclic peptides, pahayokolides A (1) and B (2), is described. Structural features determined for these compounds include a pendent N-acetyl-N-methyl leucine, both E- and Z-dehydrobutyrines, a homophenylalanine, and an unusual polyhydroxy amino acid that is most likely of mixed polyketide synthase/nonribosomal peptide synthase origin. These peptides were purified from a new species of cyanobacteria of the genus Lyngbya, which was isolated from a periphyton mat from the Florida Everglades.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Kathleen S. Rein
- Corresponding author. Tel: (305) 348−6682. Fax: (305) 348−3772. E-mail:
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Simovic D, Di M, Marks V, Chatfield DC, Rein KS. 1,3-dipolar cycloadditions of trimethylsilyldiazomethane revisited: steric demand of the dipolarophile and the influence on product distribution. J Org Chem 2007; 72:650-3. [PMID: 17221990 PMCID: PMC2631184 DOI: 10.1021/jo061838t] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [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: 11/28/2022]
Abstract
The 1,3-dipolar cycloaddition of trimethylsilyldiazomethane with alpha,beta-unsaturated esters was examined. The resulting 1-pyrazolines isomerize to regioisomeric 2-pyrazolines (a or b) or undergo desilylation (c). Acrylates yield only b or c. beta-Substituted dipolarophiles may yield all three types of products. This work demonstrates that the distribution of 2-pyrazoline products is highly dependent on the relative configuration of the substituents on the 1-pyrazoline intermediate.
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Affiliation(s)
- Dragan Simovic
- Department of Chemistry, Florida International University, Miami, Florida 33199, USA
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28
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Affiliation(s)
- Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, USA
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Snyder RV, Guerrero MA, Sinigalliano CD, Winshell J, Perez R, Lopez JV, Rein KS. Localization of polyketide synthase encoding genes to the toxic dinoflagellate Karenia brevis. Phytochemistry 2005; 66:1767-80. [PMID: 16051286 PMCID: PMC2573037 DOI: 10.1016/j.phytochem.2005.06.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Revised: 04/25/2005] [Indexed: 05/03/2023]
Abstract
Karenia brevis is a toxic marine dinoflagellate endemic to the Gulf of Mexico. Blooms of this harmful alga cause fish kills, marine mammal mortalities and neurotoxic shellfish poisonings. These harmful effects are attributed to a suite of polyketide secondary metabolites known as the brevetoxins. The carbon framework of all polyketides is assembled by a polyketide synthase (PKS). Previously, PKS encoding genes were amplified from K. brevis culture and their similarity to a PKS gene from the closely related protist, Cryptosporidium parvum, suggested that these genes originate from the dinoflagellate. However, K. brevis has not been grown axenically. The associated bacteria might be the source of the toxins or the PKS genes. Herein we report the localization of PKS encoding genes by a combination of flow cytometry/PCR and fluorescence in situ hybridization (FISH). Two genes localized exclusively to K. brevis cells while a third localized to both K. brevis and associated bacteria. While these genes have not yet been linked to toxin production, the work describes the first definitive evidence of resident PKS genes in any dinoflagellate.
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Affiliation(s)
- Richard V. Snyder
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th St., University Park, Miami, FL 33199, United States
| | - Maria A. Guerrero
- The Southeast Environmental Research Center, Florida International University, 11200 SW 8th St., Miami, FL 33199, United States
| | - Christopher D. Sinigalliano
- The Southeast Environmental Research Center, Florida International University, 11200 SW 8th St., Miami, FL 33199, United States
| | - Jamie Winshell
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th St., University Park, Miami, FL 33199, United States
| | - Roberto Perez
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th St., University Park, Miami, FL 33199, United States
| | - Jose V. Lopez
- Division of Biomedical Marine Research, Harbor Branch Oceanographic Institution, 5600 US 1 North, Ft. Pierce, FL 34946, United States
| | - Kathleen S. Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th St., University Park, Miami, FL 33199, United States
- Corresponding author. Tel.: +1 305 348 6682; fax: +1 305 348 3772. E-mail address: (K.S. Rein)
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Rodriguez J, Carcache L, Rein KS. Low-mode docking search in iGluR homology models implicates three residues in the control of ligand selectivity. J Mol Recognit 2005; 18:183-9. [PMID: 15476293 DOI: 10.1002/jmr.713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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: 11/05/2022]
Abstract
Homology models of the ionotropic rat kainate receptor iGluR6, based on the ligand binding domains of iGluR2, were constructed. A systematic analysis by low-mode docking searches of kainic acid in homology models of the native iGluR6 receptor, chimeric (iGluR2 and iGluR6) receptors and mutant receptors have identified three residues which influence the conformation of kainic acid in the binding core and hence the affinity for kainic acid. These residues are Leu650, Thr649 and Leu704, all located in domain 2. Leu650 has previously been implicated in the control of selectivity of iGluR2. However, this is the first report that suggests that Thr649 and Leu704 play a role in receptor selectivity.
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Affiliation(s)
- Jonierr Rodriguez
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th St., Miami, FL 33199, USA
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Berry JP, Gantar M, Gawley RE, Wang M, Rein KS. Pharmacology and toxicology of pahayokolide A, a bioactive metabolite from a freshwater species of Lyngbya isolated from the Florida Everglades. Comp Biochem Physiol C Toxicol Pharmacol 2004; 139:231-8. [PMID: 15683832 PMCID: PMC2573041 DOI: 10.1016/j.cca.2004.11.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Revised: 11/17/2004] [Accepted: 11/17/2004] [Indexed: 11/29/2022]
Abstract
The genus of filamentous cyanobacteria, Lyngbya, has been found to be a rich source of bioactive metabolites. However, identification of such compounds from Lyngbya has largely focused on a few marine representatives. Here, we report on the pharmacology and toxicology of pahayokolide A from a freshwater isolate, Lyngbya sp. strain 15-2, from the Florida Everglades. Specifically, we investigated inhibition of microbial representatives and mammalian cell lines, as well as toxicity of the compound to both invertebrate and vertebrate models. Pahayokolide A inhibited representatives of Bacillus, as well as the yeast, Saccharomyces cerevisiae. Interestingly, the compound also inhibited several representatives of green algae that were also isolated from the Everglades. Pahayokolide A was shown to inhibit a number of cancer cell lines over a range of concentrations (IC50 varied from 2.13 to 44.57 microM) depending on the cell-type. When tested against brine shrimp, pahayokolide was only marginally toxic at the highest concentrations tested (1 mg/mL). The compound was, however, acutely toxic to zebrafish embryos (LC50=2.15 microM). Possible biomedical and environmental health aspects of the pahayokolides remain to be investigated; however, the identification of bioactive metabolites such as these demonstrates the potential of the Florida Everglades as source of new toxins and drugs.
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Affiliation(s)
- John P Berry
- Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA.
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Abstract
The kainoids are a class of excitatory and excitotoxic pyrrolidine dicarboxylates that act at ionotropic glutamate receptors. The kainoids bind kainate receptors with high affinity and, while binding affinity is lower at AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptors, they are active in functional assays at this receptor subtype as well. However, kainoids are only partial agonists at AMPA receptors. Currents evoked by kainoids have been described as either slowly desensitizing, partially desensitizing, or non-desensitizing. Recently acquired X-ray crystal structures of the ligand binding domain of the iGluR2, AMPA sensitive receptor suggest that differences in ligand-receptor interactions may influence functional properties of an agonist. In an effort to identify important ligand-receptor interactions of various kainoids, we have conducted a series of low-mode docking searches of AMPA agonists in the iGluR2 binding domain. Kainic acid exhibited alternate low-lying geometries, with loss of hydrogen bonds to domain 2, which may represent a dissociation route not available to other kainoids. The most potent of the kainoids are capable of forming hydrogen bonding interactions that span the two domains of the receptor. In particular, a hydrogen bond between the domoic acid C6' carboxylic acid and Ser652 may prevent a peptide bond rotation that is associated with the desensitized state of the receptor.
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Affiliation(s)
- Luis M Carcache
- Department of Chemistry, Florida International University, 11200 SW 8th St., FL 33199, Miami, USA
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Snyder RV, Gibbs PDL, Palacios A, Abiy L, Dickey R, Lopez JV, Rein KS. Polyketide synthase genes from marine dinoflagellates. Mar Biotechnol (NY) 2003; 5:1-12. [PMID: 12925913 DOI: 10.1007/s10126-002-0077-y] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2002] [Accepted: 09/05/2002] [Indexed: 05/24/2023]
Abstract
Rapidly developing techniques for manipulating the pathways of polyketide biosynthesis at the genomic level have created the demand for new pathways with novel biosynthetic capability. Polyketides derived from dinoflagellates are among the most complex and unique structures identified thus far, yet no studies of the biosynthesis of dinoflagellate-derived polyketides at the genomic level have been reported. Nine strains representing 7 different species of dinoflagellates were screened for the presence of type I and type II polyketide synthases (PKSs) by polymerase chain reaction (PCR) and reverse transcriptase PCR. Seven of the 9 strains yielded products that were homologous with known and putative type I PKSs. Unexpectedly, a PKS gene was amplified from cultures of the dinoflagellate Gymnodinium catenatum, a saxitoxin producer, which is not known to produce a polyketide. In each case the presence of a PKS gene was correlated with the presence of bacteria in the cultures as identified by amplification of the bacterial 16S ribosomal RNA gene. However, amplification from polyadenylated RNA, the lack of PKS expression in light-deprived cultures, residual phylogenetic signals, resistance to methylation-sensitive restriction enzymes, and the lack of hybridization to bacterial isolates support a dinoflagellate origin for most of these genes.
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Affiliation(s)
- R V Snyder
- Department of Chemistry, Florida International University, 11200 SW 8th St., Miami, FL 33199, USA
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Berry JP, Reece KS, Rein KS, Baden DG, Haas LW, Ribeiro WL, Shields JD, Snyder RV, Vogelbein WK, Gawley RE. Are Pfiesteria species toxicogenic? Evidence against production of ichthyotoxins by Pfiesteria shumwayae. Proc Natl Acad Sci U S A 2002; 99:10970-5. [PMID: 12163648 PMCID: PMC123194 DOI: 10.1073/pnas.172221699] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [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: 04/12/2002] [Indexed: 11/18/2022] Open
Abstract
The estuarine genus Pfiesteria has received considerable attention since it was first identified and proposed to be the causative agent of fish kills along the mid-Atlantic coast in 1992. The presumption has been that the mechanism of fish death is by release of one or more toxins by the dinoflagellate. In this report, we challenge the notion that Pfiesteria species produce ichthyotoxins. Specifically, we show that (i) simple centrifugation, with and without ultrasonication, is sufficient to "detoxify" water of actively fish-killing cultures of Pfiesteria shumwayae, (ii) organic extracts of lyophilized cultures are not toxic to fish, (iii) degenerate primers that amplify PKS genes from several polyketide-producing dinoflagellates failed to yield a product with P. shumwayae DNA or cDNA, and (iv) degenerate primers for NRPS genes failed to amplify any NRPS genes but (unexpectedly) yielded a band (among several) that corresponded to known or putative PKSs and fatty acid synthases. We conclude that P. shumwayae is able to kill fish by means other than releasing a toxin into bulk water. Alternative explanations of the effects attributed to Pfiesteria are suggested.
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Affiliation(s)
- J P Berry
- Department of Chemistry/National Institute of Environmental Health Sciences, Marine and Freshwater Biomedical Science Center, University of Miami, P.O. Box 249118, Coral Gables, FL 33124, USA
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Rein KS, Gawley RE. Synthesis of the phthalide isoquinoline alkaloids (-)-egenine, (-)-corytensine, and (-)-bicuculline by asymmetric carbonyl addition of chiral dipole-stabilized organometallics. J Org Chem 2002. [DOI: 10.1021/jo00004a041] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Rein KS, Lynn B, Gawley RE, Baden DG. Brevetoxin B: Chemical Modifications, Synaptosome Binding, Toxicity, and an Unexpected Conformational Effect. J Org Chem 2002. [DOI: 10.1021/jo00087a028] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Rein KS, Baden DG, Gawley RE. Conformational Analysis of the Sodium Channel Modulator, Brevetoxin A, Comparison with Brevetoxin B Conformations, and a Hypothesis about the Common Pharmacophore of the "Site 5" Toxins. J Org Chem 2002. [DOI: 10.1021/jo00087a027] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Rein KS, Gawley RE. Analysis of (.alpha.-hydroxybenzyl)tetrahydroisoquinoline stereoisomers by Pirkle column HPLC: correlation of absolute configuration with order of elution. J Org Chem 2002. [DOI: 10.1021/jo00002a062] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
BACKGROUND The brevetoxins are marine neurotoxins that interfere with the normal functions of the voltage-gated Na(+) channel. We have identified two brevetoxin derivatives that do not exhibit pharmacological properties typical of the brevetoxins and that function as brevetoxin antagonists. RESULTS PbTx-3 and benzoyl-PbTx-3 elicited Na(+) channel openings during steady-state depolarizations; however, two PbTx-3 derivatives retained their ability to bind to the receptor, but did not elicit Na(+) channel openings. alpha-Naphthoyl-PbTx-3 acted as a PbTx-3 antagonist but did not affect Na(+) channels that were not exposed to PbTx-3. beta-Naphthoyl-PbTx-3 reduced openings of Na(+) channels that were not exposed to PbTx-3. CONCLUSIONS Some modifications to the brevetoxin molecule do not alter either the binding properties or the activity of these toxins. Larger modifications to the K-ring sidechain do not interfere with binding but have profound effects on their pharmacological properties. This implies a critical function for the K-ring sidechain of the native toxin.
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Affiliation(s)
- S L Purkerson-Parker
- Neurotoxicology Division MD-74B, University of North Carolina Curriculum in Toxicology, United States Environmental Protection Agency, NC 27711, USA
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Abstract
Dinoflagellates, unicellular marine protists, produce some of the largest and most complex polyketides identified to date. The biological activities of these compounds are quite diverse. Compounds having potential therapeutic value as anti-cancer agents as well as deadly neurotoxins, whose production has resulted in severe public health hazards and economic hardships, are represented in this group of secondary metabolites. Stable isotope feeding experiments have firmly established the polyketide origins of representative compounds from each of the three structural classes, the polyether ladders, the macrocycles and the linear polyethers. Yet some unusual labeling patterns have been observed in each class. Pendant methyl groups are most often derived from C-2 of acetate and deletions of C-1 of acetate are common. Studies on the biosynthesis of dinoflagellate derived polyketides at the genomic level have not been reported, in part due to the peculiarities of the dinoflagellate nucleus and the lack of a dinoflagellate transformation system. Nevertheless, a fundamental understanding of the genetics of polyketide biosynthesis by dinoflagellates could be the catalyst for developing several fruitful avenues of research. Dinoflagellate derived polyketides are reviewed with special emphasis on pharmacology and biosynthesis.
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Affiliation(s)
- K S Rein
- Department of Chemistry, Florida International University, Miami 33199, USA.
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Washburn BS, Rein KS, Baden DG, Walsh PJ, Hinton DE, Tullis K, Denison MS. Brevetoxin-6 (PbTx-6), a nonaromatic marine neurotoxin, is a ligand of the aryl hydrocarbon receptor. Arch Biochem Biophys 1997; 343:149-56. [PMID: 9224724 DOI: 10.1006/abbi.1997.0149] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [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: 02/04/2023]
Abstract
Brevetoxins (PbTx) are a family of marine polyether toxins that exert their toxic action by activating voltage-sensitive sodium channels. Two forms of brevetoxin, PbTx-2 and -3, induce hepatic cytochrome P4501A1, measured as ethoxyresorufin O-deethylase (EROD) activity, in redfish and striped bass. P4501A1 induction is transcriptionally regulated through the binding of a ligand, typically a planar aromatic compound, to the aryl hydrocarbon receptor (AhR) and subsequent complex formation with the dioxin response element (DRE), an upstream regulatory region of the CYP1A1 gene. To determine if PbTx, a nonaromatic compound, induced EROD by this mechanism, two sets of experiments were performed. Initially, saturation binding assays with PbTx-2, -3, and -6 were carried out to determine if PbTx-2, -3, or -6 was an AhR ligand. Results showed that PbTx-6 inhibited specific binding of dioxin to the AhR, whereas PbTx-2 and -3 had no effect. Subsequently, gel retardation assays showed that PbTx-6 caused a concentration-dependent increase in AhR-DRE complex formation. The most abundant and neurotoxic forms of brevetoxin, PbTx-2 and -3, did not appear to be involved in this process. However, PbTx-6, the epoxide which is a likely biotransformation product, is at least one of the forms of PbTx involved in EROD induction.
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Affiliation(s)
- B S Washburn
- Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, University of California, Davis 95616, USA
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Gawley RE, Rein KS, Jeglitsch G, Adams DJ, Theodorakis EA, Tiebes J, Nicolaou KC, Baden DG. The relationship of brevetoxin 'length' and A-ring functionality to binding and activity in neuronal sodium channels. Chem Biol 1995; 2:533-41. [PMID: 9383457 DOI: 10.1016/1074-5521(95)90187-6] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Brevetoxins are polyether ladder toxins that are ichthyotoxic at nanomolar concentrations. They bind to voltage-gated sodium channels, causing four distinct electrophysiological effects: (i) a shift of activation potential; (ii) occurrence of subconductance states; (iii) induction of longer mean open times of the channel; and (iv) inhibition of channel inactivation. We set out to determine whether these functions all require the same structural elements within the brevetoxin molecules. RESULTS Several synthetically prepared structural analogs of brevetoxin B were examined in synaptosome receptor binding assays and by functional electrophysiological measurements. A truncated analog is not ichthyotoxic at micromolar concentrations, shows decreased receptor-binding affinity, and causes only a shift of activation potential without affecting mean open times or channel inactivation. An analog with the A-ring carbonyl removed binds to the receptor with nanomolar affinity, produces a shift of activation potential and inhibits inactivation, but does not induce longer mean open times. An analog in which the A-ring diol is reduced shows low binding affinity, yet populates five subconductance states. CONCLUSIONS Our data are consistent with the hypothesis that binding to sodium channels requires an elongated cigar-shaped molecule, approximately 30 A long. The four electrophysiological effects of the brevetoxins are not produced by a single structural feature, however, since they can be decoupled by using modified ligands, which are shown here to be partial sodium channel agonists. We propose a detailed model for the binding of brevetoxins to the channel which explains the differences in the effects of the brevetoxin analogs. These studies also offer the potential for developing brevetoxin antagonists.
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Affiliation(s)
- R E Gawley
- Department of Chemistry, University of Miami, Coral Gables, FL 33124, USA
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Crouch RC, Martin GE, Dickey RW, Baden DG, Gawley RE, Rein KS, Mazzola EP. Brevetoxin-3: Total assignment of the 1H and 13C NMR spectra at the submicromole level. Tetrahedron 1995. [DOI: 10.1016/0040-4020(95)00360-k] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Baden DG, Melinek R, Sechet V, Trainer VL, Schultz DR, Rein KS, Tomas CR, Delgado J, Hale L. Modified immunoassays for polyether toxins: implications of biological matrixes, metabolic states, and epitope recognition. J AOAC Int 1995; 78:499-508. [PMID: 7538840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Polyether marine toxins are responsible for the seafood intoxication phenomena known as neurotoxic shellfish poisoning (due to brevetoxins), ciguatera (due to ciguatoxin), and diarrheic shellfish poisoning (due to okadaic acid). Using traditional techniques of hapten (pure toxin) conjugation to protein to create complete antigen, animal immunization and antibody isolation, and specific antibody subpopulation purification, discriminating antibodies have been isolated that detect brevetoxins and ciguatoxin, but not okadaic acid, in a dose-dependent fashion. Using microorganic chemistry and purified toxins, a unique set of tools has been created for the study of polyether ladder toxin accumulation; depuration; and specific site localization in tissues, food sources, and clinical samples. Developed test protocols can detect toxin in dinoflagellate cells, in extracts from food sources, in seawater and culture media, and in human serum samples. Enzyme-linked immunosorbent assay protocols developed for eventual collaborative testing have been successful in limited applications within the laboratory (correlation coefficient of 0.92 excluding 2 outliers), and alternative formats are being developed to optimize the basic test for use in research laboratories, regulatory laboratories, and field inspections.
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Affiliation(s)
- D G Baden
- NIEHS Marine and Freshwater Biomedical Sciences Center, University of Miami, FL 33149, USA
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Poli MA, Rein KS, Baden DG. Radioimmunoassay for PbTx-2-type brevetoxins: epitope specificity of two anti-PbTx sera. J AOAC Int 1995; 78:538-42. [PMID: 7538841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Antiserum against PbTx-2-type brevetoxins was produced by immunizing rabbits with a PbTx-2-bovine serum albumin (BSA) conjugate. This serum had a higher affinity, but lower titer, than our current goat serum. Using 4 natural brevetoxins and 6 synthetic derivatives as competitors in our brevetoxin radioimmunoassay, we determined the epitope specificity of both sera. Modification of the backbone structure at C-42 on the K-ring had little or no effect on the antigen-binding capability of either serum. Reduction of the double bond between C-2 and C-3 on the A-ring by reduction of the lactone decreased binding 500 to 750-fold. Epoxidation of the double bond between C-27 and C-28 on the H-ring did not affect binding, which suggested that the goat serum is specific for the A-ring region of the brevetoxin backbone. In contrast, modifying the A-ring had no effect on rabbit serum binding. However, epoxidation of the H-ring decreased binding 5 to 20-fold, which suggested that the rabbit antiserum is specific for the H-ring region of the molecule. These results suggest that assays utilizing only one antibody may not adequately detect toxin metabolites if molecules are altered in the critical region of antibody recognition.
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Affiliation(s)
- M A Poli
- U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21702-5011, USA
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Abstract
The epitopic regions of the brevetoxin PbTx-3 molecule, produced by the marine dinoflagellate Ptychodiscus brevis, have been identified by structural modification at three distinct regions of the toxin. These are: the A-ring lactone region of the molecule, the K-ring side-chain and the H-ring. The modified PbTx-3 derivatives were tested for their ability to bind brevetoxin goat antisera directed against the PbTx-3 molecule, by radioimmunoassay. The results showed that at least two major epitopes and one minor epitope are recognized: the A-ring lactone region of the molecule and the K-ring side-chain, and the H-ring. The results illustrate the variety of antibodies which may be produced, even within a species, and suggests that epitope characterization is important in the development of assays which are to be employed in seafood safety issues.
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Affiliation(s)
- R Melinek
- Marine and Freshwater Biomedical Sciences Center, University of Miami, FL 33149
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Baden DG, Rein KS, Gawley RE, Jeglitsch G, Adams DJ. Is the A-ring lactone of brevetoxin PbTx-3 required for sodium channel orphan receptor binding and activity? Nat Toxins 1994; 2:212-21. [PMID: 7952946 DOI: 10.1002/nt.2620020410] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Brevetoxin PbTx-3 and non-toxic derivative 4 were investigated for their abilities to bind to the specific brevetoxin receptor site on rat brain synaptosomes and to modulate the normal function of voltage-gated sodium channels as determined by patch clamping of cultured neurons. Compounds 4 and 5 are produced from PbTx-3 by opening of the A-ring lactone to the saturated and unsaturated diols using sodium borohydride in ethanol. Natural PbTx-3 exhibited tighter binding to rat brain synaptosomes by at least 3 orders of magnitude as determined by competitive radioligand binding experiments, and was also more effective at activating voltage-gated channels. Patch clamping revealed the 3 orders of magnitude greater potency of PbTx-3 toxin over 5, although each produced delayed sodium channel opening and a pronounced delay in inactivation. Conformational modeling of the Brevetoxin B backbone indicates that the two molecules are identical except for the region of the A-Ring lactone. Thus, we conclude that the brevetoxin PbTx-3 backbone requires electrophilic functionality in the region of the lactone in PbTx-3, and that opening of the ring in 5 is sufficient to substantially reduce both binding and activity.
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Affiliation(s)
- D G Baden
- Marine and Freshwater Biomedical Sciences Center, RSMAS University of Miami, Florida
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Gawley RE, Rein KS, Kinoshita M, Baden DG. Binding of brevetoxins and ciguatoxin to the voltage-sensitive sodium channel and conformational analysis of brevetoxin B. Toxicon 1992; 30:780-5. [PMID: 1324537 DOI: 10.1016/0041-0101(92)90014-v] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.6] [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: 12/26/2022]
Abstract
The marine toxins known generically as brevetoxins, as well as their structural relative ciguatoxin, are known as polyether ladder toxins, and bind uniquely to site 5 of the voltage-sensitive sodium channel. Rat brain synaptosome binding data show similarities in binding affinity for brevetoxins having the same structural (ladder) backbone, but different affinities between brevetoxins having different backbones. Ciguatoxin has a different backbone from the brevetoxins, but binds even more strongly to the same site. Could the flexibility of the backbone be related to their relative toxicities? As part of an effort to identify the common pharmacophore for the toxins, Monte Carlo methods were used to generate conformational models of the polyether ladder toxin brevetoxin B (PbTx-2) which shows significant flexibility at the juncture of the two 7-membered rings.
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Affiliation(s)
- R E Gawley
- Department of Chemistry, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Coral Gables, FL 33124-0431
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Rein KS, Chen ZH, Perumal P, Echegoyen L, Gawley RE. Single electron transfer in the addition of chiral dipole-stabilized organolithiums to carbonyls. Stereochemistry of a chiral nucleophile as a mechanistic probe. Tetrahedron Lett 1991. [DOI: 10.1016/0040-4039(91)85007-r] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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