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Feng J, Jin R, Cheng S, Li H, Wang X, Chen K. Establishing an Artificial Pathway for the Biosynthesis of Octopamine and Synephrine. ACS Synth Biol 2024; 13:1762-1772. [PMID: 38815614 DOI: 10.1021/acssynbio.4c00082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
In this study, we designed an artificial pathway composed of tyramine β-hydroxylase (TBH) and phenylethanolamine N-methyltransferase (PNMT) for the biosynthesis of both octopamine and synephrine. As most TBH and PNMT originate from eukaryotic animals and plants, the heterologous expression and identification of functional TBH and PNMT are critical for establishing the pathway in mode microorganisms like Escherichia coli. Here, three TBHs were evaluated, and only TBH from Drosophila melanogaster was successfully expressed in the soluble form in E. coli. Its expression was promoted by evaluating the effects of different expression strategies. The specific enzyme activity of TBH was optimized up to 229.50 U·g-1, and the first step in the biosynthetic pathway was successfully established and converted tyramine to synthesize 0.10 g/L of octopamine. Furthermore, the second step to produce synephrine from octopamine was developed by screening PNMT, enhancing enzyme activity, and optimizing reaction conditions, with a maximum synephrine production of 2.02 g/L. Finally, based on the optimization of the reaction conditions for each individual reaction, the one-pot cascade reaction for synthesizing synephrine from tyramine was constructed by combining the TBH and PNMT. The synthetic synephrine reached 30.05 mg/L with tyramine as substrate in the two-step enzyme cascade system. With further optimization and amplification, the titers of octopamine and synephrine were increased to 0.45 and 0.20 g/L, respectively, with tyramine as substrate. This work was the first achievement of the biosynthesis of octopamine and synephrine to date.
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Affiliation(s)
- Jiao Feng
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Runyuan Jin
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Shasha Cheng
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Hui Li
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Xin Wang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Kequan Chen
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China
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Theoretical perspective on mononuclear copper-oxygen mediated C–H and O–H activations: A comparison between biological and synthetic systems. CHINESE JOURNAL OF CATALYSIS 2022. [DOI: 10.1016/s1872-2067(21)63974-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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3
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Quek SY, Debnath S, Laxmi S, van Gastel M, Krämer T, England J. Sterically Stabilized End-On Superoxocopper(II) Complexes and Mechanistic Insights into Their Reactivity with O-H, N-H, and C-H Substrates. J Am Chem Soc 2021; 143:19731-19747. [PMID: 34783549 DOI: 10.1021/jacs.1c07837] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Instability of end-on superoxocopper(II) complexes, with respect to conversion to peroxo-bridged dicopper(II) complexes, has largely constrained their study to very low temperatures. This limits their kinetic capacity to oxidize substrates. In response, we have developed a series of bulky ligands, Ar3-TMPA (Ar = tpb, dpb, dtbpb), and used them to support copper(I) complexes that react with O2 to yield [CuII(η1-O2•-)(Ar3-TMPA)]+ species, which are stable against dimerization at all temperatures. Binding of O2 saturates at subambient temperatures and can be reversed by warming. The onset of oxygenation for the Ar = tpb and dpb systems is observed at 25 °C, and all three [CuII(η1-O2•-)(Ar3-TMPA)]+ complexes are stable against self-decay at temperatures of ≤-20 °C. This provides a wide temperature window for study of these complexes, which was exploited by performing extensive reaction kinetics measurements for [CuII(η1-O2•-)(tpb3-TMPA)]+ using a broad range of O-H, N-H, and C-H bond substrates. This includes correlation of second order rate constants (k2) versus oxidation potentials (Eox) for a range of phenols, construction of Eyring plots, and temperature-dependent kinetic isotope effect (KIE) measurements. The data obtained indicate that reaction with all substrates proceeds via H atom transfer (HAT), reaction with the phenols proceeds with significant charge transfer, and full tunneling of both H and D atoms occurs in the case of 1,2-diphenylhydrazine and 4-methoxy-2,6-di-tert-butylphenol. Oxidation of C-H bonds proved to be kinetically challenging, and whereas [CuII(η1-O2•-)(tpb3-TMPA)]+ can oxidize moderately strong O-H and N-H bonds, it is only able to oxidize very weak C-H bonds.
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Affiliation(s)
- Sebastian Y Quek
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Suman Debnath
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Shoba Laxmi
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr D-45470, Germany
| | - Tobias Krämer
- Department of Chemistry, Maynooth University, Maynooth, Co. Kildare W23 F2H6, Ireland.,Hamilton Institute, Maynooth University, Maynooth, Co. Kildare W23 F2H6, Ireland
| | - Jason England
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.,Department of Chemistry, University of Lincoln, Lincoln LN6 7TW, U.K
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Rao VKS, Eipper BA, Mains RE. Multiple roles for peptidylglycine α-amidating monooxygenase in the response to hypoxia. J Cell Physiol 2021; 236:7745-7758. [PMID: 34061983 DOI: 10.1002/jcp.30457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/10/2021] [Accepted: 05/19/2021] [Indexed: 11/11/2022]
Abstract
The biosynthesis of many of the peptides involved in homeostatic control requires peptidylglycine α-amidating monooxygenase (PAM), an ancient, highly conserved copper- and ascorbate-dependent enzyme. Using the production of amidated chromogranin A to monitor PAM function in tumor cells, physiologically relevant levels of hypoxia were shown to inhibit this monooxygenase. The ability of primary pituitary cells exposed to hypoxic conditions for 4 h to produce amidated chromogranin A was similarly inhibited. The affinity of the purified monooxygenase for oxygen (Km = 99 ± 19 μM) was consistent with this result. The ability of PAM to alter secretory pathway behavior under normoxic conditions required its monooxygenase activity. Under normoxic conditions, hypoxia-inducible factor 1a levels in dense cultures of corticotrope tumor cells expressing high levels of PAM exceeded those in control cells; expression of inactive monooxygenase did not have this effect. The effects of hypoxia on levels of two PAM-regulated genes (activating transcription factor 3 [Atf3] and FK506 binding protein 2 [Fkbp2]) differed in cells expressing high versus low levels of PAM. Putative hypoxia response elements occur in both human and mouse PAM, and hPAM has consistently been identified as one of the genes upregulated in response to hypoxia. Expression of PAM is also known to alter gene expression. A quarter of the genes consistently upregulated in response to hypoxia were downregulated following increased expression of PAM. Taken together, our data suggest roles for PAM and amidated peptide secretion in the coordination of tissue-specific responses to hypoxia.
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Affiliation(s)
- Vishwanatha K S Rao
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Betty A Eipper
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut, USA.,Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Richard E Mains
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut, USA
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Wu P, Fan F, Song J, Peng W, Liu J, Li C, Cao Z, Wang B. Theory Demonstrated a "Coupled" Mechanism for O 2 Activation and Substrate Hydroxylation by Binuclear Copper Monooxygenases. J Am Chem Soc 2019; 141:19776-19789. [PMID: 31746191 DOI: 10.1021/jacs.9b09172] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Multiscale simulations have been performed to address the longstanding issue of "dioxygen activation" by the binuclear copper monooxygenases (PHM and DβM), which have been traditionally classified as "noncoupled" binuclear copper enzymes. Our QM/MM calculations rule out that CuM(II)-O2• is an active species for H-abstraction from the substrate. In contrast, CuM(II)-O2• would abstract an H atom from the cosubstrate ascorbate to form a CuM(II)-OOH intermediate in PHM and DβM. Consistent with the recently reported structural features of DβM, the umbrella sampling shows that the "open" conformation of the CuM(II)-OOH intermediate could readily transform into the "closed" conformation in PHM, in which we located a mixed-valent μ-hydroperoxodicopper(I,II) intermediate, (μ-OOH)Cu(I)Cu(II). The subsequent O-O cleavage and OH moiety migration to CuH generate the unexpected species (μ-O•)(μ-OH)Cu(II)Cu(II), which is revealed to be the reactive intermediate responsible for substrate hydroxylation. We also demonstrate that the flexible Met ligand is favorable for O-O cleavage reactions, while the replacement of Met with the strongly bound His ligand would inhibit the O-O cleavage reactivity. As such, the study not only demonstrates a "coupled" mechanism for O2 activation by binuclear copper monooxygenases but also deciphers the full catalytic cycle of PHM and DβM in accord with the available experimental data. These findings of O2 activation and substrate hydroxylation by binuclear copper monooxygenases could expand our understanding of the reactivities of the synthetic monocopper complexes.
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Affiliation(s)
- Peng Wu
- State Key Laboratory of Structural Chemistry , Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences , Fuzhou , Fujian 350002 , People's Republic of China.,University of Chinese Academy of Sciences , Beijing 100049 , People's Republic of China
| | - Fangfang Fan
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 360015 , People's Republic of China
| | - Jinshuai Song
- College of Chemistry, and Institute of Green Catalysis , Zhengzhou University , Zhengzhou 450001 , People's Republic of China
| | - Wei Peng
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 360015 , People's Republic of China
| | - Jia Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 360015 , People's Republic of China
| | - Chunsen Li
- State Key Laboratory of Structural Chemistry , Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences , Fuzhou , Fujian 350002 , People's Republic of China.,Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry , Xiamen , Fujian 361005 , People's Republic of China
| | - Zexing Cao
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 360015 , People's Republic of China
| | - Binju Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 360015 , People's Republic of China
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Kurihara K, Homma T, Kobayashi S, Shichiri M, Fujiwara H, Fujii S, Yamada KI, Nakane M, Kawamae K, Fujii J. Ascorbic acid insufficiency impairs spatial memory formation in juvenile AKR1A-knockout mice. J Clin Biochem Nutr 2019; 65:209-216. [PMID: 31777422 PMCID: PMC6877411 DOI: 10.3164/jcbn.19-41] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 06/18/2019] [Indexed: 01/18/2023] Open
Abstract
AKR1A, an aldo-keto reductase, is involved in the synthesis of ascorbic acid as well as the reduction of a variety of aldehyde compounds. AKR1A−/− mice produce considerably less ascorbic acid (about 10%) compared to AKR1A+/+ mice and require ascorbic acid supplementation in order to breed. To elucidate the roles played by AKR1A in spatial memory, AKR1A−/− male mice were weaned at 4 weeks of age and groups that received ascorbic acid supplementation and no supplementation were subjected to a Morris water maze test. Juvenile AKR1A−/− mice that received no supplementation showed impaired spatial memory formation, even though about 70% of the ascorbic acid remained in the brains of the AKR1A−/− mice at day 7 after weaning. To the contrary, the young adult AKR1A−/− mice at 13–15 weeks of age maintained only 15% of ascorbic acid but showed no significant difference in the spatial memory compared with the AKR1A+/+ mice or ascorbic acid-supplemented AKR1A−/− mice. It is conceivable that juvenile mice require more ascorbic acid for the appropriate level of formation of spatial memory and that maturation of the neural system renders the memory forming process less sensitive to an ascorbic acid insufficiency.
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Affiliation(s)
- Kazuki Kurihara
- Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, 2-2-2 Iidanishi, Yamagata 990-9585, Japan.,Department of Anesthesiology, Faculty of Medicine, Yamagata University, 2-2-2 Iidanishi, Yamagata 990-9585, Japan
| | - Takujiro Homma
- Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, 2-2-2 Iidanishi, Yamagata 990-9585, Japan
| | - Sho Kobayashi
- Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, 2-2-2 Iidanishi, Yamagata 990-9585, Japan
| | - Mototada Shichiri
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
| | - Hiroki Fujiwara
- Department of Physiology, Faculty of Medicine, Yamagata University, 2-2-2 Iidanishi, Yamagata 990-9585, Japan
| | - Satoshi Fujii
- Department of Physiology, Faculty of Medicine, Yamagata University, 2-2-2 Iidanishi, Yamagata 990-9585, Japan
| | - Ken-Ichi Yamada
- Physical Chemistry for Life Science Laboratory, Faculty of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.,AMED-CREST, Japan Agency for Medical Research and Development, 1-7-1 Otemachi, Chiyoda-ku, Tokyo, Japan
| | - Masaki Nakane
- Department of Emergency and Critical Care Medicine, Faculty of Medicine, Yamagata University, 2-2-2 Iidanishi, Yamagata 990-9585, Japan
| | - Kaneyuki Kawamae
- Department of Anesthesiology, Faculty of Medicine, Yamagata University, 2-2-2 Iidanishi, Yamagata 990-9585, Japan
| | - Junichi Fujii
- Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, 2-2-2 Iidanishi, Yamagata 990-9585, Japan
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7
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Alwan KB, Welch EF, Arias RJ, Gambill BF, Blackburn NJ. Rational Design of a Histidine-Methionine Site Modeling the M-Center of Copper Monooxygenases in a Small Metallochaperone Scaffold. Biochemistry 2019; 58:3097-3108. [PMID: 31243953 DOI: 10.1021/acs.biochem.9b00312] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mononuclear copper monooxygenases peptidylglycine monooxygenase (PHM) and dopamine β-monooxygenase (DBM) catalyze the hydroxylation of high energy C-H bonds utilizing a pair of chemically distinct copper sites (CuH and CuM) separated by 11 Å. In earlier work, we constructed single-site PHM variants that were designed to allow the study of the M- and H-centers independently in order to place their reactivity sequentially along the catalytic pathway. More recent crystallographic studies suggest that these single-site variants may not be truly representative of the individual active sites. In this work, we describe an alternative approach that uses a rational design to construct an artificial PHM model in a small metallochaperone scaffold. Using site-directed mutagenesis, we constructed variants that provide a His2Met copper-binding ligand set that mimics the M-center of PHM. The results show that the model accurately reproduces the chemical and spectroscopic properties of the M-center, including details of the methionine coordination, and the properties of Cu(I) and Cu(II) states in the presence of endogenous ligands such as CO and azide. The rate of reduction of the Cu(II) form of the model by the chromophoric reductant N,N'-dimethyl phenylenediamine (DMPD) has been compared with that of the PHM M-center, and the reaction chemistry of the Cu(I) forms with molecular oxygen has also been explored, revealing an unusually low reactivity toward molecular oxygen. This latter finding emphasizes the importance of substrate triggering of oxygen reactivity and implies that the His2Met ligand set, while necessary, is insufficient on its own to activate oxygen in these enzyme systems.
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Affiliation(s)
- Katherine B Alwan
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Evan F Welch
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Renee J Arias
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Ben F Gambill
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Ninian J Blackburn
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
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9
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Knop M, Lemnaru R, Seebeck FP. Mutation of Conserved Residues Increases in Vitro Activity of the Formylglycine-Generating Enzyme. Chembiochem 2017; 18:1755-1761. [PMID: 28605111 DOI: 10.1002/cbic.201700174] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Indexed: 01/03/2023]
Abstract
The formylglycine-generating enzyme (FGE) recognizes proteins with a specific cysteine-containing six-amino-acid motif and converts this cysteine residue into formylglycine. The resulting aldehyde function provides a unique handle for selective protein labeling. We have identified two mutations in FGE from Thermomonospora curvata that increase this catalytic efficiency more than 40-fold. The resulting activity and stability, as well as its ease of recombinant production, make this FGE variant a practical reagent for in vitro protein engineering.
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Affiliation(s)
- Matthias Knop
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
| | - Roxana Lemnaru
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
| | - Florian P Seebeck
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
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10
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Chauhan S, Hosseinzadeh P, Lu Y, Blackburn NJ. Stopped-Flow Studies of the Reduction of the Copper Centers Suggest a Bifurcated Electron Transfer Pathway in Peptidylglycine Monooxygenase. Biochemistry 2016; 55:2008-21. [PMID: 26982589 DOI: 10.1021/acs.biochem.6b00061] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptidylglycine monooxygenase (PHM) is a dicopper enzyme that plays a vital role in the amidation of glycine-extended pro-peptides. One of the crucial aspects of its chemistry is the transfer of two electrons from an electron-storing and -transferring site (CuH) to the oxygen binding site and catalytic center (CuM) over a distance of 11 Å during one catalytic turnover event. Here we present our studies of the first electron transfer (ET) step (reductive phase) in wild-type (WT) PHM as well as its variants. Stopped flow was used to record the reduction kinetic traces using the chromophoric agent N,N-dimethyl-p-phenylenediamine dihydrochloride (DMPD) as the reductant. The reduction was found to be biphasic in the WT PHM with an initial fast phase (17.2 s(-1)) followed by a much slower phase (0.46 s(-1)). We were able to ascribe the fast and slow phase to the CuH and CuM sites, respectively, by making use of the H242A and H107AH108A mutants that contain only the CuH site and CuM site, respectively. In the absence of substrate, the redox potentials determined by cyclic voltammetry were 270 mV (CuH site) and -15 mV (CuM site), but binding of substrate (Ac-YVG) was found to alter both potentials so that they converged to a common value of 83 mV. Substrate binding also accelerated the slow reductive phase by ~10-fold, an effect that could be explained at least partially by the equalization of the reduction potential of the copper centers. Studies of H108A showed that the ET to the CuM site is blocked, highlighting the role of the H108 ligand as a component of the reductive ET pathway. Strikingly, the rate of reduction of the H172A variant was unaffected despite the rate of catalysis being 3 orders of magnitude slower than that of the WT PHM. These studies strongly indicate that the reductive phase and catalytic phase ET pathways are different and suggest a bifurcated ET pathway in PHM. We propose that H172 and Y79 form part of an alternate pathway for the catalytic phase ET while the H108 ligand along with the water molecules and substrate form the reductive phase ET pathway.
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Affiliation(s)
- Shefali Chauhan
- Institute of Environmental Health, Oregon Health and Science University , 3181 Southwest Sam Jackson Park Road, Portland, Oregon 97239, United States
| | - Parisa Hosseinzadeh
- Department of Chemistry and Biochemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Yi Lu
- Department of Chemistry and Biochemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Ninian J Blackburn
- Institute of Environmental Health, Oregon Health and Science University , 3181 Southwest Sam Jackson Park Road, Portland, Oregon 97239, United States
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Maji RC, Bhandari A, Singh R, Roy S, Chatterjee SK, Bowles FL, Ghiassi KB, Maji M, Olmstead MM, Patra AK. Copper coordinated ligand thioether-S and NO2(-) oxidation: relevance to the CuM site of hydroxylases. Dalton Trans 2015; 44:17587-99. [PMID: 26390838 DOI: 10.1039/c5dt02184g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In order to gain insight into the coordination site and oxidative activity of the CuM site of hydroxylases such as peptidylglycine α-hydroxylating monooxygenase (PHM), dopamine β-monooxygenase (DβM), and tyramine β-monooxygenase (TβM), we have synthesized, characterized and studied the oxidation chemistry of copper complexes chelated by tridentate N2Sthioether, N2Osulfoxide or N2Osulfone donor sets. The ligands are those of N-2-methylthiophenyl-2'-pyridinecarboxamide (HL1), and the oxidized variants, N-2-methylsulfenatophenyl-2'-pyridinecarboxamide (HL1(SO)), and N-2-methylsulfinatophenyl-2'-pyridinecarboxamide (HL1(SO2)). Our studies afforded the complexes [(L1)Cu(II)(H2O)](ClO4)·H2O (1·H2O), {[(L1(SO))Cu(II)(CH3CN)](ClO4)}n (2), [(L1)Cu(II)(ONO)] (3), [(L1(SO))Cu(II)(ONO)]n (4), [(L1)Cu(II)(NO3)]n (5), [(L1(SO))Cu(II)(NO3)]n (6) and [(L1(SO2))Cu(II)(NO3)] (7). Complexes 1 and 3 were described in a previous publication (Inorg. Chem., 2013, 52, 11084). The X-ray crystal structures revealed either distorted octahedral (in 2, 4-6) or square-pyramidal (in 1, 3) coordination geometry around Cu(II) ions of the complexes. In the presence of H2O2, conversion of 1→2, 3-5→6 and 6→7 occurs quantitatively via oxidation of thioether-S and/or Cu(ii) coordinated NO2(-) ions. Thioether-S oxidation of L1 also occurs when [L1](-) is reacted with [Cu(I)(CH3CN)4](ClO4) in DMF under O2, albeit low in yield (20%). Oxidations of thioether-S and NO2(-) were monitored by UV-Vis spectroscopy. Recovery of the sulfur oxidized ligands from their metal complexes allowed for their characterization by elemental analysis, (1)H NMR, FTIR and mass spectrometry.
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Affiliation(s)
- Ram Chandra Maji
- Department of Chemistry, National Institute of Technology Durgapur, Mahatma Gandhi Avenue, Durgapur 713209, West Bengal, India.
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12
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Knight D, Iliadi KG, Iliadi N, Wilk R, Hu J, Krause HM, Taylor P, Moran MF, Boulianne GL. Distinct Regulation of Transmitter Release at the Drosophila NMJ by Different Isoforms of nemy. PLoS One 2015; 10:e0132548. [PMID: 26237434 PMCID: PMC4523183 DOI: 10.1371/journal.pone.0132548] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 06/17/2015] [Indexed: 11/18/2022] Open
Abstract
Synaptic transmission is highly plastic and subject to regulation by a wide variety of neuromodulators and neuropeptides. In the present study, we have examined the role of isoforms of the cytochrome b561 homologue called no extended memory (nemy) in regulation of synaptic strength and plasticity at the neuromuscular junction (NMJ) of third instar larvae in Drosophila. Specifically, we generated two independent excisions of nemy that differentially affect the expression of nemy isoforms. We show that the nemy45 excision, which specifically reduces the expression of the longest splice form of nemy, leads to an increase in stimulus evoked transmitter release and altered synaptic plasticity at the NMJ. Conversely, the nemy26.2 excision, which appears to reduce the expression of all splice forms except the longest splice isoform, shows a reduction in stimulus evoked transmitter release, and enhanced synaptic plasticity. We further show that nemy45 mutants have reduced levels of amidated peptides similar to that observed in peptidyl-glycine hydryoxylating mono-oxygenase (PHM) mutants. In contrast, nemy26.2 mutants show no defects in peptide amidation but rather display a decrease in Tyramine β hydroxylase activity (TβH). Taken together, these results show non-redundant roles for the different nemy isoforms and shed light on the complex regulation of neuromodulators.
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Affiliation(s)
- David Knight
- Program in Developmental and Stem Cell Biology, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, M5G 0A4, Canada
| | - Konstantin G. Iliadi
- Program in Developmental and Stem Cell Biology, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, M5G 0A4, Canada
| | - Natalia Iliadi
- Program in Developmental and Stem Cell Biology, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, M5G 0A4, Canada
| | - Ronit Wilk
- Department of Molecular Genetics, The Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada
| | - Jack Hu
- Department of Molecular Genetics, The Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada
| | - Henry M. Krause
- Department of Molecular Genetics, The Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada
| | - Paul Taylor
- Program in Molecular Structure and Function, The Hospital for Sick Children, Toronto, M5G 1L7, Canada
| | - Michael F. Moran
- Dept of Molecular Genetics, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
- Program in Molecular Structure and Function, The Hospital for Sick Children, Toronto, M5G 1L7, Canada
| | - Gabrielle L. Boulianne
- Program in Developmental and Stem Cell Biology, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, M5G 0A4, Canada
- Dept of Molecular Genetics, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
- * E-mail:
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13
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Zhu H, Sommerhalter M, Nguy AKL, Klinman JP. Solvent and Temperature Probes of the Long-Range Electron-Transfer Step in Tyramine β-Monooxygenase: Demonstration of a Long-Range Proton-Coupled Electron-Transfer Mechanism. J Am Chem Soc 2015; 137:5720-9. [PMID: 25919134 PMCID: PMC4970857 DOI: 10.1021/ja512388n] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
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Tyramine
β-monooxygenase (TβM) belongs to a family
of physiologically important dinuclear copper monooxygenases that
function with a solvent-exposed active site. To accomplish each enzymatic
turnover, an electron transfer (ET) must occur between two solvent-separated
copper centers. In wild-type TβM, this event is too fast to
be rate limiting. However, we have recently shown [Osborne, R. L.;
et al. Biochemistry2013, 52, 1179] that the Tyr216Ala variant of TβM leads to rate-limiting
ET. In this study, we present a pH–rate profile study of Tyr216Ala,
together with deuterium oxide solvent kinetic isotope effects (KIEs).
A solvent KIE of 2 on kcat is found in
a region where kcat is pH/pD independent.
As a control, the variant Tyr216Trp, for which ET is not rate determining,
displays a solvent KIE of unity. We conclude, therefore, that the
observed solvent KIE arises from the rate-limiting ET step in the
Tyr216Ala variant, and show
how small solvent KIEs (ca. 2) can be fully accommodated from equilibrium effects within the Marcus equation. To gain insight into the role of the enzyme in the long-range
ET step, a temperature dependence study was also pursued. The small
enthalpic barrier of ET (Ea = 3.6 kcal/mol)
implicates a significant entropic barrier, which is attributed to
the requirement for extensive rearrangement of the inter-copper environment
during PCET catalyzed by the Tyr216Ala variant. The data lead to the
proposal of a distinct inter-domain pathway for PCET in the dinuclear
copper monooxygenases.
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Affiliation(s)
| | - Monika Sommerhalter
- #Department of Chemistry and Biochemistry, California State University, East Bay, 25800 Carlos Bee Boulevard, Hayward, California 94542, United States
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14
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Kola VSR, Renuka P, Madhav MS, Mangrauthia SK. Key enzymes and proteins of crop insects as candidate for RNAi based gene silencing. Front Physiol 2015; 6:119. [PMID: 25954206 PMCID: PMC4406143 DOI: 10.3389/fphys.2015.00119] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 03/31/2015] [Indexed: 11/23/2022] Open
Abstract
RNA interference (RNAi) is a mechanism of homology dependent gene silencing present in plants and animals. It operates through 21-24 nucleotides small RNAs which are processed through a set of core enzymatic machinery that involves Dicer and Argonaute proteins. In recent past, the technology has been well appreciated toward the control of plant pathogens and insects through suppression of key genes/proteins of infecting organisms. The genes encoding key enzymes/proteins with the great potential for developing an effective insect control by RNAi approach are actylcholinesterase, cytochrome P450 enzymes, amino peptidase N, allatostatin, allatotropin, tryptophan oxygenase, arginine kinase, vacuolar ATPase, chitin synthase, glutathione-S-transferase, catalase, trehalose phosphate synthase, vitellogenin, hydroxy-3-methylglutaryl coenzyme A reductase, and hormone receptor genes. Through various studies, it is demonstrated that RNAi is a reliable molecular tool which offers great promises in meeting the challenges imposed by crop insects with careful selection of key enzymes/proteins. Utilization of RNAi tool to target some of these key proteins of crop insects through various approaches is described here. The major challenges of RNAi based insect control such as identifying potential targets, delivery methods of silencing trigger, off target effects, and complexity of insect biology are very well illustrated. Further, required efforts to address these challenges are also discussed.
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Affiliation(s)
| | | | - Maganti Sheshu Madhav
- Department of Biotechnology, Directorate of Rice Research, ICAR-Indian Institute of Rice ResearchHyderabad, India
| | - Satendra K. Mangrauthia
- Department of Biotechnology, Directorate of Rice Research, ICAR-Indian Institute of Rice ResearchHyderabad, India
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15
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Dempsey DR, Jeffries KA, Bond JD, Carpenter AM, Rodriguez-Ospina S, Breydo L, Caswell KK, Merkler DJ. Mechanistic and structural analysis of Drosophila melanogaster arylalkylamine N-acetyltransferases. Biochemistry 2014; 53:7777-93. [PMID: 25406072 PMCID: PMC4270386 DOI: 10.1021/bi5006078] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
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Arylalkylamine N-acetyltransferase (AANAT) catalyzes the penultimate step in the
biosynthesis of melatonin and other N-acetylarylalkylamides
from the corresponding arylalkylamine and acetyl-CoA. The N-acetylation
of arylalkylamines is a critical step in Drosophila melanogaster for the inactivation of the bioactive amines and the sclerotization
of the cuticle. Two AANAT variants (AANATA and AANATB) have been identified
in D. melanogaster, in which AANATA differs from
AANATB by the truncation of 35 amino acids from the N-terminus. We
have expressed and purified both D. melanogaster AANAT
variants (AANATA and AANATB) in Escherichia coli and
used the purified enzymes to demonstrate that this N-terminal truncation
does not affect the activity of the enzyme. Subsequent characterization
of the kinetic and chemical mechanism of AANATA identified an ordered
sequential mechanism, with acetyl-CoA binding first, followed by tyramine.
We used a combination of pH–activity profiling and site-directed
mutagenesis to study prospective residues believed to function in
AANATA catalysis. These data led to an assignment of Glu-47 as the
general base in catalysis with an apparent pKa of 7.0. Using the data generated for the kinetic mechanism,
structure–function relationships, pH–rate profiles,
and site-directed mutagenesis, we propose a chemical mechanism for
AANATA.
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Affiliation(s)
- Daniel R Dempsey
- Department of Chemistry, University of South Florida , Tampa, Florida 33620, United States
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16
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Solomon EI, Heppner DE, Johnston EM, Ginsbach JW, Cirera J, Qayyum M, Kieber-Emmons MT, Kjaergaard CH, Hadt RG, Tian L. Copper active sites in biology. Chem Rev 2014; 114:3659-853. [PMID: 24588098 PMCID: PMC4040215 DOI: 10.1021/cr400327t] [Citation(s) in RCA: 1138] [Impact Index Per Article: 113.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
| | - David E. Heppner
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | | | - Jake W. Ginsbach
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Jordi Cirera
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Munzarin Qayyum
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | | | | | - Ryan G. Hadt
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Li Tian
- Department of Chemistry, Stanford University, Stanford, CA, 94305
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17
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Influence of resuscitation fluids, fresh frozen plasma and antifibrinolytics on fibrinolysis in a thrombelastography-based, in-vitro, whole-blood model. Blood Coagul Fibrinolysis 2013; 24:489-97. [PMID: 23406662 DOI: 10.1097/mbc.0b013e32835e4246] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Hyperfibrinolysis has been identified as a mechanism of trauma coagulopathy associated with poor outcome. The aim of the study was to create a trauma coagulopathy model (TCM) with a hyperfibrinolysis thrombelastography (TEG) pattern similar to injured patients and test the effects of different resuscitation fluids and antifibrinolytics on fibrinolysis. TCM was established from whole blood by either 15% dilution with isotonic saline, lactated Ringer's, Plasma-Lyte, 5% albumin, Voluven, Hextend, 6% dextran in isotonic saline or 30% dilution with lactated Ringer's plus Voluven and supplementation with tissue factor and tissue plasminogen activator (tPA). These combinations resulted in a TCM that could then be 'treated' with tranexamic acid (TXA) or 6-aminocaproic acid (ACA). Clot formation was evaluated by TEG. Whole-blood dilution by 15% with crystalloids and albumin in the presence of tissue factor plus tPA resulted in an abnormal TEG pattern and increased fibrinolysis, as did dilution with synthetic colloids. TXA 1 μg/ml or ACA 10 μg/ml were sufficient to suppress fibrinolysis when TCM was diluted 15% with lactated Ringer's, but 3 μg/ml of TXA or 30 μg/ml of ACA were needed for fibrinolysis inhibition induced by simultaneous euvolemic dilution with lactated Ringer's plus Voluven by 30%. A total of 15% dilution of whole blood in the presence of tissue factor plus tPA results in a hyperfibrinolysis TEG pattern similar to that observed in severely injured patients. Synthetic colloids worsen TEG variables with a further increase of fibrinolysis. Low concentrations of TXA or ACA reversed hyperfibrinolysis, but the efficient concentrations were dependent on the degree of fibrinolysis and whole-blood dilution.
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18
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Klinman JP. The power of integrating kinetic isotope effects into the formalism of the Michaelis-Menten equation. FEBS J 2013; 281:489-97. [PMID: 23937475 DOI: 10.1111/febs.12477] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 07/25/2013] [Accepted: 07/29/2013] [Indexed: 11/29/2022]
Abstract
The final arbiter of enzyme mechanism is the ability to establish and test a kinetic mechanism. Isotope effects play a major role in expanding the scope and insight derived from the Michaelis-Menten equation. The integration of isotope effects into the formalism of the Michaelis-Menten equation began in the 1970s and has continued until the present. This review discusses a family of eukaryotic copper proteins, including dopamine β-monooxygenase, tyramine β-monooxygenase and peptidylglycine α-amidating enzyme, which are responsible for the synthesis of neuroactive compounds, norepinephrine, octopamine and C-terminally carboxamidated peptides, respectively. The review highlights the results of studies showing how combining kinetic isotope effects with initial rate parameters permits the evaluation of: (a) the order of substrate binding to multisubstrate enzymes; (b) the magnitude of individual rate constants in complex, multistep reactions; (c) the identification of chemical intermediates; and (d) the role of nonclassical (tunnelling) behaviour in C-H activation.
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Affiliation(s)
- Judith P Klinman
- Departments of Chemistry and Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA
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19
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Fuenzalida-Uribe N, Meza RC, Hoffmann HA, Varas R, Campusano JM. nAChR-induced octopamine release mediates the effect of nicotine on a startle response in Drosophila melanogaster. J Neurochem 2013; 125:281-90. [DOI: 10.1111/jnc.12161] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 11/29/2012] [Accepted: 12/20/2012] [Indexed: 11/29/2022]
Affiliation(s)
- Nicolás Fuenzalida-Uribe
- Departamento de Biología Celular y Molecular; Pontificia Universidad Católica de Chile; Millennium Nucleus Stress and Addiction (NEDA); Santiago CHILE
| | - Rodrigo C. Meza
- Departamento de Fisiología; Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Millennium Nucleus Stress and Addiction (NEDA); Santiago CHILE
| | - Hernán A. Hoffmann
- Facultad de Medicina; Pontificia Universidad Católica de Chile; Millennium Nucleus Stress and Addiction (NEDA); Santiago CHILE
| | - Rodrigo Varas
- Departamento de Fisiología; Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Millennium Nucleus Stress and Addiction (NEDA); Santiago CHILE
| | - Jorge M. Campusano
- Departamento de Biología Celular y Molecular; Pontificia Universidad Católica de Chile; Millennium Nucleus Stress and Addiction (NEDA); Santiago CHILE
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20
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Osborne RL, Zhu H, Iavarone AT, Blackburn NJ, Klinman JP. Interdomain long-range electron transfer becomes rate-limiting in the Y216A variant of tyramine β-monooxygenase. Biochemistry 2013; 52:1179-91. [PMID: 23320946 DOI: 10.1021/bi3013609] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The enzyme tyramine β-monooxygenase (TβM) belongs to a small eukaryotic family of physiologically important mononuclear dicopper monooxygenases. The properties of this family include noncoupled mononuclear copper centers ~11 Å apart, with Cu(M) performing C-H and O(2) activation and Cu(H) functioning as an electron storage site [Klinman, J. P. (2006) J. Biol. Chem. 281, 3013-3016]. A conserved tyrosine (Y216 in TβM) is positioned between the copper domains and is associated with Cu(H) (through an interaction with a Cu(H)-coordinating histidine). Mutations at Y216 (to W, I, and A) indicate little or no difference in electron paramagnetic resonance spectra, while X-ray absorption spectroscopy studies show only a very small decrease in distance between Cu(M) and its Met471 ligand in reduced enzyme. High-performance liquid chromatography assays demonstrate that turnover of substrate is complete with Y216W and Y216I, whereas Y216A undergoes a secondary inactivation that is linked to oxidation of ligands at Cu(M). Steady-state kinetic and isotope effect measurements were investigated. The significantly elevated K(m,Tyr) for Y216A, together with a very large (D)(k(cat)/K(m,Tyr)) of ~12, indicates a major impact on the binding of substrate at the Cu(M) site. The kinetic and isotopic parameters lead to estimated rate constants for C-H bond cleavage, dissociation of substrate from the Cu(M) site, and, in the case of Y216A, the rate of electron transfer (ET) from Cu(H) to Cu(M). These studies uncover a rate-limiting ET within the solvent-filled interface and lead to a paradigm shift in our understanding of the mononuclear dicopper monooxygenases.
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Affiliation(s)
- Robert L Osborne
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
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21
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Osborne RL, Zhu H, Iavarone AT, Hess CR, Klinman JP. Inactivation of Met471Cys tyramine β-monooxygenase results from site-specific cysteic acid formation. Biochemistry 2012; 51:7488-95. [PMID: 22891760 PMCID: PMC3567250 DOI: 10.1021/bi300456f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Tyramine β-monooxygenase (TβM), the insect homologue of dopamine β-monooxygenase, is a neuroregulatory enzyme that catalyzes the β-hydroxylation of tyramine to yield octopamine. Mutation of the methionine (Met) ligand to Cu(M) of TβM, Met471Cys, yielded a form of TβM that is catalytically active but susceptible to inactivation during turnover [Hess, C. R., Wu, Z., Ng, A., Gray, E. E., McGuirl, M. M., and Klinman, J. P. (2008) J. Am. Chem. Soc. 130, 11939-11944]. Further, although the wild-type (WT) enzyme undergoes coordination of Met471 to Cu(M) in its reduced form, the generation of Met471Cys almost completely eliminates this interaction [Hess, C. R., Klinman, J. P., and Blackburn, N. J. (2010) J. Biol. Inorg. Chem. 15, 1195-1207]. The aim of this study is to identify the chemical consequence of the poor ability of Cys to coordinate Cu(M). We show that Met471Cys TβM is ~5-fold more susceptible to inactivation than the WT enzyme in the presence of the cosubstrate/reductant ascorbate and that this process is not facilitated by the substrate tyramine. The resulting 50-fold smaller ratio for turnover to inactivation in the case of Met471Cys prevents full turnover of the substrate under all conditions examined. Liquid chromatography-tandem mass spectrometry analysis of proteolytic digests of inactivated Met471Cys TβM leads to the identification of cysteic acid at position 471. While both Met and Cys side chains are expected to be similarly subject to oxidative damage in proteins, the enhanced reactivity of Met471Cys toward solution oxidants in TβM is attributed to its weaker interaction with Cu(I)(M).
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Affiliation(s)
- Robert L. Osborne
- Department of Chemistry, and the California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, USA
| | - Hui Zhu
- Department of Chemistry, and the California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, USA
| | - Anthony T. Iavarone
- Department of Chemistry, and the California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, USA
| | - Corinna R. Hess
- Department of Chemistry, and the California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, USA
| | - Judith P. Klinman
- Department of Chemistry, and the California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, USA
- Department of Molecular and Cell Biology, and the California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, USA
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22
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The copper centers of tyramine β-monooxygenase and its catalytic-site methionine variants: an X-ray absorption study. J Biol Inorg Chem 2010; 15:1195-207. [PMID: 20544364 PMCID: PMC2988203 DOI: 10.1007/s00775-010-0677-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Accepted: 05/12/2010] [Indexed: 10/31/2022]
Abstract
Tyramine β-monooxygenase (TBM) is a member of a family of copper monooxygenases containing two noncoupled copper centers, and includes peptidylglycine monooxygenase and dopamine β-monooxygenase. In its Cu(II) form, TBM is coordinated by two to three His residues and one to two non-His O/N ligands consistent with a [Cu(M)(His)(2)(OH(2))(2)-Cu(H)(His)(3)(OH(2))] formulation. Reduction to the Cu(I) state causes a change in the X-ray absorption spectroscopy (XAS) spectrum, consistent with a change to a [Cu(M)(His)(2)S(Met)-Cu(H)(His)(3)] environment. Lowering the pH to 4.0 results in a large increase in the intensity of the Cu(I)-S extended X-ray absorption fine structure (EXAFS) component, suggesting a tighter Cu-S bond or the coordination of an additional sulfur donor. The XAS spectra of three variants, where the Cu(M) Met471 residue had been mutated to His, Cys, and Asp, were examined. Significant differences from the wild-type enzyme are evident in the spectra of the reduced mutants. Although the side chains of His, Cys, and Asp are expected to substitute for Met at the Cu(M) site, the data showed identical spectra for all three reduced variants, with no evidence for coordination of residue 471. Rather, the K-edge data suggested a modest decrease in coordination number, whereas the EXAFS indicated an average of two His residues at each Cu(I) center. These data highlight the unique role of the Met residue at the Cu(M) center, and pose interesting questions as to why replacement by the cuprophilic thiolate ligand leads to detectable activity whereas replacement by imidazole generates inactive TBM.
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23
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Miyakawa H, Imai M, Sugimoto N, Ishikawa Y, Ishikawa A, Ishigaki H, Okada Y, Miyazaki S, Koshikawa S, Cornette R, Miura T. Gene up-regulation in response to predator kairomones in the water flea, Daphnia pulex. BMC DEVELOPMENTAL BIOLOGY 2010; 10:45. [PMID: 20433737 PMCID: PMC2888767 DOI: 10.1186/1471-213x-10-45] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Accepted: 04/30/2010] [Indexed: 11/10/2022]
Abstract
BACKGROUND Numerous cases of predator-induced polyphenisms, in which alternate phenotypes are produced in response to extrinsic stimuli, have been reported in aquatic taxa to date. The genus Daphnia (Branchiopoda, Cladocera) provides a model experimental system for the study of the developmental mechanisms and evolutionary processes associated with predator-induced polyphenisms. In D. pulex, juveniles form neckteeth in response to predatory kairomones released by Chaoborus larvae (Insecta, Diptera). RESULTS Previous studies suggest that the timing of the sensitivity to kairomones in D. pulex can generally be divided into the embryonic and postembryonic developmental periods. We therefore examined which of the genes in the embryonic and first-instar juvenile stages exhibit different expression levels in the presence or absence of predator kairomones. Employing a candidate gene approach and identifying differentially-expressed genes revealed that the morphogenetic factors, Hox3, extradenticle and escargot, were up-regulated by kairomones in the postembryonic stage and may potentially be responsible for defense morph formation. In addition, the juvenile hormone pathway genes, JHAMT and Met, and the insulin signaling pathway genes, InR and IRS-1, were up-regulated in the first-instar stage. It is well known that these hormonal pathways are involved in physiological regulation following morphogenesis in many insect species. During the embryonic stage when morphotypes were determined, one of the novel genes identified by differential display was up-regulated, suggesting that this gene may be related to morphotype determination. Biological functions of the up-regulated genes are discussed in the context of defense morph formation. CONCLUSIONS It is suggested that, following the reception of kairomone signals, the identified genes are involved in a series of defensive phenotypic alterations and the production of a defensive phenotype.
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Affiliation(s)
- Hitoshi Miyakawa
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
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24
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Hess CR, Wu Z, Ng A, Gray EE, McGuirl MA, Klinman JP. Hydroxylase activity of Met471Cys tyramine beta-monooxygenase. J Am Chem Soc 2008; 130:11939-44. [PMID: 18710228 DOI: 10.1021/ja800408h] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A series of mutations was targeted at the methionine residue, Met471, coordinating the Cu(M) site of tyramine beta-monooxygenase (TbetaM). The methionine ligand at Cu(M) is believed to be key to dioxygen activation and the hydroxylation chemistry of the copper monooxygenases. The reactivity and copper binding properties of three TbetaM mutants, Met471Asp, Met471Cys, and Met471His, were examined. All three mutants show similar metal binding affinities to wild type TbetaM in the oxidized enzyme forms. EPR spectroscopy suggests that the Cu(II) coordination geometry is identical to that of the WT enzyme. However, substrate hydroxylation was observed for the reaction of tyramine solely with Met471Cys TbetaM. Met471Cys TbetaM provides the first example of an active mutant directed at the Cu(M) site of this class of hydroxylases. The reactivity and altered kinetics of the Met471Cys mutant further highlight the central role of the methionine residue in the enzyme mechanism. The sole ability of the cysteine residue to support activity among the series of alternate amino acids investigated is relevant to theoretical and biomimetic investigations of dioxygen activation at mononuclear copper centers.
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Affiliation(s)
- Corinna R Hess
- Department of Chemistry, University of California, Berkeley, California 94720-3220, USA
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