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Zhang S, Ma M, Zhao C, Li J, Xu L, Zhang Z, Diao Q, Ma P, Song D. A novel low-background nitroreductase fluorescent probe for real-time fluorescence imaging and surgical guidance of thyroid cancer resection. Biosens Bioelectron 2024; 261:116514. [PMID: 38908291 DOI: 10.1016/j.bios.2024.116514] [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] [Received: 05/15/2024] [Revised: 06/17/2024] [Accepted: 06/19/2024] [Indexed: 06/24/2024]
Abstract
Thyroid cancer always appears insidiously with few noticeable clinical symptoms. Due to its limitations, conventional ultrasound imaging can lead to missed or misdiagnosed cases. Surgery is still the primary treatment method of thyroid cancer, but removal of surrounding healthy tissues to minimize recurrence leads to overtreatment and added patient suffering. To address this challenge, herein, a nitroreductase (NTR) fluorescent probe, Ox-NTR, has been developed for detecting thyroid cancer and tracking the surgical removal of thyroid tumors by fluorescence imaging. The conjugated structure of oxazine 1 was disrupted, significantly reducing the issue of high background signals, thus effectively achieving low background fluorescence. Under hypoxic conditions, the nitro group of Ox-NTR can be reduced to an amine and subsequently decomposed into oxazine 1, emitting intense red fluorescence. Ox-NTR has a low detection limit of 0.09 μg/mL for NTR with excellent photostability and selectivity. Cellular studies show that Ox-NTR can effectively detect NTR levels in hypoxic thyroid cancer cells. Moreover, the ability of Ox-NTR of rapid response to thyroid cancer in vivo is confirmed by fluorescence imaging in mice, distinguishing tumors from normal tissues due to its superior low background fluorescence. Utilizing this fluorescence imaging method during surgical resection can guide the removal of tumors, preventing both missed tumor tissues and accidental removal of healthy tissue. In summary, the novel Ox-NTR offers precise detection capabilities that provide significant advantages over traditional imaging methods for thyroid cancer diagnosis and treatment, making it a valuable tool to guide tumor removal in surgical procedures.
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Affiliation(s)
- Siqi Zhang
- College of Chemistry, Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, Jilin University, Qianjin Street 2699, Changchun, 130012, China
| | - Mo Ma
- College of Chemistry, Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, Jilin University, Qianjin Street 2699, Changchun, 130012, China; School of Pharmacy, Jilin University, Qianjin Street 2699, Changchun, 130012, China
| | - Chen Zhao
- College of Chemistry, Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, Jilin University, Qianjin Street 2699, Changchun, 130012, China
| | - Jingkang Li
- College of Chemistry, Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, Jilin University, Qianjin Street 2699, Changchun, 130012, China
| | - Lanlan Xu
- College of Chemistry, Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, Jilin University, Qianjin Street 2699, Changchun, 130012, China
| | - Zihe Zhang
- The First Hospital of China Medical University, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, 110122, China
| | - Quanping Diao
- Liaoning Key Laboratory of Development and Utilization for Natural Products Active Molecules, School of Chemistry and Life Science, Anshan Normal University, Anshan, China
| | - Pinyi Ma
- College of Chemistry, Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, Jilin University, Qianjin Street 2699, Changchun, 130012, China.
| | - Daqian Song
- College of Chemistry, Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, Jilin University, Qianjin Street 2699, Changchun, 130012, China; Liaoning Key Laboratory of Development and Utilization for Natural Products Active Molecules, School of Chemistry and Life Science, Anshan Normal University, Anshan, China.
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Da Y, Sun Q, Zhang L, Tian Y. Light-activated g-C 3N 4 photoelectrodes with a selective molecular sieve for in vivo quantification of oxygen levels in the living mouse brain. Chem Commun (Camb) 2024. [PMID: 38465876 DOI: 10.1039/d4cc00246f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
A novel micro-photoelectrode with a selective molecular sieve was created for in vivo monitoring of O2 levels in the mouse brain. An ITO optical fiber modified by graphitized carbon nitride (g-C3N4) in situ was employed as the light activated substrate to provide rich photo-induced electrons for the catalytic reduction of O2. Meanwhile, the porous hybrid layer composed of zeolitic imidazolate framework-8 and polysulfone was constructed over the g-C3N4 surface as the molecular sieve to synergically enhance the selectivity of O2 detections. By advantage of this useful tool, the real time variation of the O2 level was successfully determined in the mouse brain upon ischemia.
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Affiliation(s)
- Yifan Da
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, School of Chemistry and Molecular Engineering, East China Normal University, Dongchuan Road 500, Shanghai 200241, China.
| | - Qi Sun
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, School of Chemistry and Molecular Engineering, East China Normal University, Dongchuan Road 500, Shanghai 200241, China.
| | - Limin Zhang
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, School of Chemistry and Molecular Engineering, East China Normal University, Dongchuan Road 500, Shanghai 200241, China.
| | - Yang Tian
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, School of Chemistry and Molecular Engineering, East China Normal University, Dongchuan Road 500, Shanghai 200241, China.
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3
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Park DY, Hwang J, Kim Y, Lee D, Kim YY, Kim HS, Hwang I. Antimicrobial activity of Limosilactobacillus fermentum strains isolated from the human oral cavity against Streptococcus mutans. Sci Rep 2023; 13:7969. [PMID: 37198248 DOI: 10.1038/s41598-023-35168-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Accepted: 05/13/2023] [Indexed: 05/19/2023] Open
Abstract
Oral probiotics have been recently gaining much attention owing to their potential to inhibit the progression of dental caries by controlling the cariogenic effects of Streptococcus mutans. We isolated and genotypically identified 77 lactic acid bacteria including 12 Limosilactobacillus fermentum probiotic candidates from the oral cavity of healthy volunteers. Among the 12 L. fermentum isolates, nine isolates effectively inhibited the growth of S. mutans via hydrogen peroxide (H2O2) production. The others neither suppressed the growth of S. mutans nor produced H2O2. Eight out of the nine H2O2-producing L. fermentum isolates exhibited strong adherence to oral epithelial KB cells while inhibiting the adherence of S. mutans to KB cells. The eight H2O2-producing isolates were neither haemolytic based on a blood-agar test, cytotoxic according to lactate dehydrogenase assay, nor resistant to eight antibiotics represented by the European Food Safety Authority guideline, indicating that the isolates have potential to suppress the cariogenesis driven by S. mutans while providing general probiotic benefits.
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Affiliation(s)
| | | | - Yunji Kim
- Apple Tree Institute of Biomedical Science, Apple Tree Medical Foundation, Goyang-Si, South Korea
| | - Dahye Lee
- Apple Tree Dental Hospital, Apple Tree Medical Foundation, Goyang-Si, South Korea
| | - Young-Youn Kim
- Apple Tree Institute of Biomedical Science, Apple Tree Medical Foundation, Goyang-Si, South Korea
- Apple Tree Dental Hospital, Apple Tree Medical Foundation, Goyang-Si, South Korea
| | - Hye-Sung Kim
- Apple Tree Institute of Biomedical Science, Apple Tree Medical Foundation, Goyang-Si, South Korea
- Apple Tree Dental Hospital, Apple Tree Medical Foundation, Goyang-Si, South Korea
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Pimviriyakul P, Kapaothong Y, Tangsupatawat T. Heterologous Expression and Characterization of a Full-length Protozoan Nitroreductase from Leishmania orientalis isolate PCM2. Mol Biotechnol 2023; 65:556-569. [PMID: 36042106 DOI: 10.1007/s12033-022-00556-3] [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] [Received: 06/29/2022] [Accepted: 08/22/2022] [Indexed: 11/25/2022]
Abstract
Leishmaniasis, a parasitic disease found in parts of the tropics and subtropics, is caused by Leishmania protozoa infection. Nitroreductases (NTRs), enzymes involved in nitroaromatic prodrug activation, are attractive targets for leishmaniasis treatment development. In this study, a full-length recombinant NTR from the Leishmania orientalis isolate PCM2 (LoNTR), which causes severe leishmaniasis in Thailand, was successfully expressed in soluble form using chaperone co-expression in Escherichia coli BL21(DE3). The purified histidine-tagged enzyme (His6-LoNTR) had a subunit molecular mass of 36 kDa with no cofactor bound; however, the addition of exogenous flavin (either FMN or FAD) readily increased its enzyme activity. Bioinformatics analysis found that the unique N-terminal sequences of LoNTR is only present in Leishmania where the addition of this region might result in the loss of flavin binding. Either NADH or NADPH can serve as an electron donor to transfer electrons to nitrofurazone; however, NADPH was preferred. Molecular oxygen was identified as an additional electron acceptor resulting in wasteful electrons from NADPH for the main catalysis. Steady-state kinetic experiments revealed a ping-pong mechanism for His6-LoNTR with Km,NADPH, Km,NFZ, and kcat of 28 µM, 68 µM, and 0.84 min-1, respectively. Besides nitroreductase activity, His6-LoNTR also has the ability to reduce quinone derivatives. The properties of full-length His6-LoNTR were different from previously reported protozoa and bacterial NTRs in many respects. This study provides information of NTR catalysis to be developed as a potential future therapeutic target to treat leishmaniasis.
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Affiliation(s)
- Panu Pimviriyakul
- Department of Biochemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand.
| | - Yuvarun Kapaothong
- Department of Biochemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand
| | - Theerapat Tangsupatawat
- Department of Biochemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand
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5
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Santiago-Arcos J, Velasco-Lozano S, López-Gallego F. Multienzyme Coimmobilization on Triheterofunctional Supports. Biomacromolecules 2023; 24:929-942. [PMID: 36649203 PMCID: PMC10018741 DOI: 10.1021/acs.biomac.2c01364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Immobilized multienzyme systems are gaining momentum in applied biocatalysis; however, the coimmobilization of several enzymes on one carrier is still challenging. In this work, we exploited a heterofunctional support activated with three different chemical functionalities to immobilize a wide variety of different enzymes. This support is based on agarose microbeads activated with aldehyde, amino, and cobalt chelate moieties that allow a fast and irreversible immobilization of enzymes, enhancing the thermostability of most of the heterogeneous biocatalysts (up to 21-fold higher than the soluble one). Furthermore, this trifunctional support serves to efficiently coimmobilize a multienzyme system composed of an alcohol dehydrogenase, a reduced nicotinamide adenine dinucleotide (NADH) oxidase, and a catalase. The confined multienzymatic system demonstrates higher performance than its free counterpart, achieving a total turnover number (TTN) of 1 × 105 during five batch consecutive cycles. We envision this solid material as a platform for coimmobilizing multienzyme systems with enhanced properties to catalyze stepwise biotransformations.
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Affiliation(s)
- Javier Santiago-Arcos
- Heterogeneous Biocatalysis Laboratory, CIC biomaGUNE, Edificio Empresarial "C", Paseo de Miramón 182, 20009 Donostia, Spain
| | - Susana Velasco-Lozano
- Heterogeneous Biocatalysis Laboratory, CIC biomaGUNE, Edificio Empresarial "C", Paseo de Miramón 182, 20009 Donostia, Spain.,Instituto de Síntesis Química y Catálisis Homogénea (ISQCH-CSIC), Universidad de Zaragoza, C/ Pedro Cerbuna, 12, 50009 Zaragoza, Spain.,Aragonese Foundation for Research and Development (ARAID), 50018 Zaragoza, Spain
| | - Fernando López-Gallego
- Heterogeneous Biocatalysis Laboratory, CIC biomaGUNE, Edificio Empresarial "C", Paseo de Miramón 182, 20009 Donostia, Spain.,IKERBASQUE, Basque Foundation for Science, 48009 Bilbao, Spain
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6
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Cirqueira ML, Bortot LO, Bolean M, Aleixo MAA, Luccas PH, Costa-Filho AJ, Ramos AP, Ciancaglini P, Nonato MC. Trypanosoma cruzi nitroreductase: Structural features and interaction with biological membranes. Int J Biol Macromol 2022; 221:891-899. [PMID: 36100001 DOI: 10.1016/j.ijbiomac.2022.09.073] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 08/28/2022] [Accepted: 09/08/2022] [Indexed: 11/05/2022]
Abstract
Due to its severe burden and geographic distribution, Chagas disease (CD) has a significant social and economic impact on low-income countries. Benznidazole and nifurtimox are currently the only drugs available for CD. These are prodrugs activated by reducing the nitro group, a reaction catalyzed by nitroreductase type I enzyme from Trypanosoma cruzi (TcNTR), with no homolog in the human host. The three-dimensional structure of TcNTR, and the molecular and chemical bases of the selective activation of nitro drugs, are still unknown. To understand the role of TcNTR in the basic parasite biology, investigate its potential as a drug target, and contribute to the fight against neglected tropical diseases, a combined approach using multiple biophysical and biochemical methods together with in silico studies was employed in the characterization of TcNTR. For the first time, the interaction of TcNTR with membranes was demonstrated, with a preference for those containing cardiolipin, a unique dimeric phospholipid that exists almost exclusively in the inner mitochondrial membrane in eukaryotic cells. Prediction of TcNTR's 3D structure suggests that a 23-residue long insertion (199 to 222), absent in the homologous bacterial protein and identified as conserved in protozoan sequences, mediates enzyme specificity, and is involved in protein-membrane interaction.
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Affiliation(s)
- Marília L Cirqueira
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo (FCFRP-USP), Ribeirão Preto, SP, Brazil
| | - Leandro O Bortot
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo (FCFRP-USP), Ribeirão Preto, SP, Brazil; Laboratory of Computational Biology (LBC), Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil
| | - Maytê Bolean
- Chemistry Dept., Faculty of Philosophy, Sciences and Letters at Ribeirão Preto, University of São Paulo (FFCLRP-USP), Ribeirão Preto, SP, Brazil
| | - Mariana A A Aleixo
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo (FCFRP-USP), Ribeirão Preto, SP, Brazil; Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil
| | - Pedro H Luccas
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo (FCFRP-USP), Ribeirão Preto, SP, Brazil
| | - Antonio J Costa-Filho
- Physics Dept., Faculty of Philosophy, Sciences and Letters at Ribeirão Preto, University of São Paulo (FFCLRP-USP), Ribeirão Preto, SP, Brazil
| | - Ana Paula Ramos
- Chemistry Dept., Faculty of Philosophy, Sciences and Letters at Ribeirão Preto, University of São Paulo (FFCLRP-USP), Ribeirão Preto, SP, Brazil
| | - Pietro Ciancaglini
- Chemistry Dept., Faculty of Philosophy, Sciences and Letters at Ribeirão Preto, University of São Paulo (FFCLRP-USP), Ribeirão Preto, SP, Brazil
| | - M Cristina Nonato
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo (FCFRP-USP), Ribeirão Preto, SP, Brazil.
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Zhou W, Li L, Qin R, Zhu J, Liu S, Mo S, Shi Z, Fang H, Ruan P, Cheng J, Fu G, Zheng N. Non-contact biomimetic mechanism for selective hydrogenation of nitroaromatics on heterogeneous metal nanocatalysts. Sci China Chem 2022. [DOI: 10.1007/s11426-021-1198-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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8
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Liu F, Zhang H, Li K, Xie Y, Li Z. A Novel NIR Fluorescent Probe for Highly Selective Detection of Nitroreductase and Hypoxic-Tumor-Cell Imaging. Molecules 2021; 26:molecules26154425. [PMID: 34361578 PMCID: PMC8347683 DOI: 10.3390/molecules26154425] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 07/18/2021] [Accepted: 07/19/2021] [Indexed: 02/05/2023] Open
Abstract
Nitroreductase as a potential biomarker for aggressive tumors has received extensive attention. In this work, a novel NIR fluorescent probe for nitroreductase detection was synthesized. The probe Py-SiRh-NTR displayed excellent sensitivity and selectivity. Most importantly, the confocal fluorescence imaging demonstrated that HepG-2 cells treated with Py-SiRh-NTR under hypoxic conditions showed obvious enhanced fluorescence, which means that the NTR was overexpressed under hypoxic conditions. Moreover, the probe showed great promise that could help us to study related anticancer mechanisms research.
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Affiliation(s)
- Feng Liu
- Department of Thyroid Surgery, West China Hospital of Sichuan University, Chengdu 610041, China; (F.L.); (Y.X.)
- Laboratory of Thyroid and Parathyroid Disease, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Hong Zhang
- College of Chemistry, Sichuan University, Chengdu 610041, China; (H.Z.); (K.L.)
| | - Kun Li
- College of Chemistry, Sichuan University, Chengdu 610041, China; (H.Z.); (K.L.)
| | - Yongmei Xie
- Department of Thyroid Surgery, West China Hospital of Sichuan University, Chengdu 610041, China; (F.L.); (Y.X.)
| | - Zhihui Li
- Department of Thyroid Surgery, West China Hospital of Sichuan University, Chengdu 610041, China; (F.L.); (Y.X.)
- Laboratory of Thyroid and Parathyroid Disease, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital of Sichuan University, Chengdu 610041, China
- Correspondence:
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Shabdar S, Anaclet B, Castineiras AG, Desir N, Choe N, Crane EJ, Sazinsky MH. Structural and Kinetic Characterization of Hyperthermophilic NADH-Dependent Persulfide Reductase from Archaeoglobus fulgidus. ARCHAEA (VANCOUVER, B.C.) 2021; 2021:8817136. [PMID: 33776585 PMCID: PMC7969121 DOI: 10.1155/2021/8817136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 02/04/2021] [Accepted: 02/24/2021] [Indexed: 11/18/2022]
Abstract
NADH-dependent persulfide reductase (Npsr) has been proposed to facilitate dissimilatory sulfur respiration by reducing persulfide or sulfane sulfur-containing substrates to H2S. The presence of this gene in the sulfate and thiosulfate-reducing Archaeoglobus fulgidus DSM 4304 and other hyperthermophilic Archaeoglobales appears anomalous, as A. fulgidus is unable to respire S0 and grow in the presence of elemental sulfur. To assess the role of Npsr in the sulfur metabolism of A. fulgidus DSM 4304, the Npsr from A. fulgidus was characterized. AfNpsr is specific for persulfide and polysulfide as substrates in the oxidative half-reaction, exhibiting k cat/K m on the order of 104 M-1 s-1, which is similar to the kinetic parameters observed for hyperthermophilic CoA persulfide reductases. In contrast to the bacterial Npsr, AfNpsr exhibits low disulfide reductase activity with DTNB; however, similar to the bacterial enzymes, it does not show detectable activity with CoA-disulfide, oxidized glutathione, or cystine. The 3.1 Å X-ray structure of AfNpsr reveals access to the tightly bound catalytic CoA, and the active site Cys 42 is restricted by a flexible loop (residues 60-66) that is not seen in the bacterial homologs from Shewanella loihica PV-4 and Bacillus anthracis. Unlike the bacterial enzymes, AfNpsr exhibits NADH oxidase activity and also shows no detectable activity with NADPH. Models suggest steric and electrostatic repulsions of the NADPH 2'-phosphate account for the strong preference for NADH. The presence of Npsr in the nonsulfur-reducing A. fulgidus suggests that the enzyme may offer some protection against S0 or serve in another metabolic role that has yet to be identified.
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Affiliation(s)
- Sherwin Shabdar
- Department of Biology, Pomona College, 175 West 6th Street, Claremont, CA 91711, USA
| | - Bukuru Anaclet
- Department of Chemistry, Pomona College, 645 N. College Ave., Claremont, CA, USA 91711
| | | | - Neyissa Desir
- Department of Chemistry, Pomona College, 645 N. College Ave., Claremont, CA, USA 91711
| | - Nicholas Choe
- Department of Biology, Pomona College, 175 West 6th Street, Claremont, CA 91711, USA
| | - Edward J. Crane
- Department of Biology, Pomona College, 175 West 6th Street, Claremont, CA 91711, USA
| | - Matthew H. Sazinsky
- Department of Chemistry, Pomona College, 645 N. College Ave., Claremont, CA, USA 91711
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Su H, Guan G, Ahmed RZ, Lyu L, Li Z, Jin X. TBBPA stimulated cell migration of endometrial cancer via the contribution of NOX-generated ROS in lieu of energy metabolism. JOURNAL OF HAZARDOUS MATERIALS 2020; 400:123204. [PMID: 32569978 DOI: 10.1016/j.jhazmat.2020.123204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 06/08/2020] [Accepted: 06/10/2020] [Indexed: 05/06/2023]
Abstract
Due to the extensive applications and deleterious effects of Tetrabromobisphenol A (TBBPA), the health risk and possible mechanisms have been a topic of concern. However, the knowledge on carcinogenic risk of TBBPA and corresponding mechanisms remains scarce. In this study, endometrial cancer cells were exposed to low doses of TBBPA and its main derivatives including TBBPA bis (2,3-dibromopropyl ether) (TBBPA-BDBPE) and TBBPA bis (2-hydroxyethyl ether) (TBBPA-BHEE). The data from wound healing and transwell assays demonstrated that TBBPA treatment exhibited the strongest enhanced effect on cell migration among other tested treatments. Of note, the process of invasion rather than epithelial-mesenchymal transition (EMT) was accompanied by the occurrence of migration elevated by TBBPA. Furthermore, the levels of several metabolite indicators were measured to assess the underlying mechanisms involved in TBBPA-induced cell migration. The findings suggested that NADPH oxidase (NOX)-driven ROS instead of energy metabolism was sensitive to TBBPA stimulation. In addition, molecular docking supported a link between TBBPA ligand and NOX receptor. Accordingly, this study has provided new insights for TBBPA-induced carcinogenic effects and may arise peoples' vigilance to environmental pollution of brominated flame retardant.
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Affiliation(s)
- Huilan Su
- Institutes of Biomedical Sciences, Shanxi University, Taiyuan, China; School of Public Health, Qingdao University, Qingdao, China
| | - Ge Guan
- School of Public Health, Qingdao University, Qingdao, China
| | - Rifat Zubair Ahmed
- Dept. of Genetics, University of Karachi, Karachi, Pakistan; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China
| | - Liang Lyu
- Institutes of Biomedical Sciences, Shanxi University, Taiyuan, China
| | - Zhuoyu Li
- School of Life Sciences, Shanxi University, Taiyuan, China
| | - Xiaoting Jin
- School of Public Health, Qingdao University, Qingdao, China.
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11
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Yan VC, Butterfield HE, Poral AH, Yan MJ, Yang KL, Pham CD, Muller FL. Why Great Mitotic Inhibitors Make Poor Cancer Drugs. Trends Cancer 2020; 6:924-941. [PMID: 32536592 PMCID: PMC7606322 DOI: 10.1016/j.trecan.2020.05.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/12/2020] [Accepted: 05/19/2020] [Indexed: 12/13/2022]
Abstract
Chemotherapy is central to oncology, perceived to operate only on prolific cancerous tissue. Yet, many non-neoplastic tissues are more prolific compared with typical tumors. Chemotherapies achieve sufficient therapeutic windows to exert antineoplastic activity because they are prodrugs that are bioactivated in cancer-specific environments. The advent of precision medicine has obscured this concept, favoring the development of high-potency kinase inhibitors. Inhibitors of essential mitotic kinases exemplify this paradigm shift, but intolerable on-target toxicities in more prolific normal tissues have led to repeated failures in the clinic. Proliferation rates alone cannot be used to achieve cancer specificity. Here, we discuss integrating the cancer specificity of prodrugs from classical chemotherapeutics and the potency of mitotic kinase inhibitors to generate a class of high-precision cancer therapeutics.
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Affiliation(s)
- Victoria C Yan
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA.
| | | | - Anton H Poral
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Matthew J Yan
- Department of Chemistry, Boston College, Chestnut Hill, MA 02467, USA
| | - Kristine L Yang
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Cong-Dat Pham
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Florian L Muller
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA.
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Dabravolski SA. Evolutionary aspects of the Viridiplantae nitroreductases. J Genet Eng Biotechnol 2020; 18:60. [PMID: 33025290 PMCID: PMC7538488 DOI: 10.1186/s43141-020-00073-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 09/14/2020] [Indexed: 11/10/2022]
Abstract
Background Nitroreductases are a family of evolutionarily related proteins catalyzing the reduction of nitro-substituted compounds. Nitroreductases are widespread enzymes, but nearly all modern research and practical application have been concentrated on the bacterial proteins, mainly nitroreductases of Escherichia coli. The main aim of this study is to describe the phylogenic distribution of the nitroreductases in the photosynthetic eukaryotes (Viridiplantae) to highlight their structural similarity and areas for future research and application. Results This study suggests that homologs of nitroreductase proteins are widely presented also in Viridiplantae. Maximum likelihood phylogenetic tree reconstruction method and comparison of the structural models suggest close evolutional relation between cyanobacterial and Viridiplantae nitroreductases. Conclusions This study provides the first attempt to understand the evolution of nitroreductase protein family in Viridiplantae. Our phylogeny estimation and preservation of the chloroplasts/mitochondrial localization indicate the evolutional origin of the plant nitroreductases from the cyanobacterial endosymbiont. A defined high level of the similarity on the structural level suggests conservancy also for the functions. Directions for the future research and industrial application of the Viridiplantae nitroreductases are discussed.
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Affiliation(s)
- Siarhei A Dabravolski
- Department of Clinical Diagnostics, Vitebsk State Academy of Veterinary Medicine [UO VGAVM], 7/11 Dovatora St., 210026, Vitebsk, Belarus.
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Kamasaka K, Kawamoto J, Chen C, Yokoyama F, Imai T, Ogawa T, Kurihara T. Genetic characterization and functional implications of the gene cluster for selective protein transport to extracellular membrane vesicles of Shewanella vesiculosa HM13. Biochem Biophys Res Commun 2020; 526:525-531. [PMID: 32245618 DOI: 10.1016/j.bbrc.2020.03.125] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 03/21/2020] [Indexed: 10/24/2022]
Abstract
A hyper-vesiculating Gram-negative bacterium, Shewanella vesiculosa HM13, secretes a protein of unknown function (P49) as a major cargo of the extracellular membrane vesicles (EMVs). Here, we analyzed the transport mechanism of P49 to EMVs. The P49 gene is found in a gene cluster containing the genes encoding homologs of surface glycolipid biosynthesis proteins (Wza, WecA, LptA, and Wzx), components of type II secretion system (T2SS), glycerophosphodiester phosphodiesterase (GdpD), and nitroreductase (NfnB). We disrupted the genes in this cluster and analyzed the productivity and morphology of EMVs and the localization of P49. EMV production and morphology were only moderately affected by gene disruption, demonstrating that these gene products are not essential for EMV synthesis. In contrast, the localization of P49 was significantly affected by gene disruption. The lack of homologs of the T2SS components resulted in deficiency in secretion of P49. When gdpD, wzx, lptA, and nfnB were disrupted, P49 was released to the extracellular space without being loaded to the EMVs. These results suggest that P49 is translocated across the outer membrane through the T2SS-like machinery and subsequently loaded onto EMVs through interaction with surface glycolipids of EMVs.
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Affiliation(s)
- Kouhei Kamasaka
- Institute for Chemical Research, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan
| | - Jun Kawamoto
- Institute for Chemical Research, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan
| | - Chen Chen
- Institute for Chemical Research, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan
| | - Fumiaki Yokoyama
- Institute for Chemical Research, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan
| | - Tomoya Imai
- Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan
| | - Takuya Ogawa
- Institute for Chemical Research, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan
| | - Tatsuo Kurihara
- Institute for Chemical Research, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan.
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14
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Functional Characterization and Structural Analysis of NADH Oxidase Mutants from Thermus thermophilus HB27: Role of Residues 166, 174, and 194 in the Catalytic Properties and Thermostability. Microorganisms 2019; 7:microorganisms7110515. [PMID: 31683638 PMCID: PMC6921046 DOI: 10.3390/microorganisms7110515] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 10/25/2019] [Accepted: 10/28/2019] [Indexed: 11/16/2022] Open
Abstract
The Thermus thermophilus strain HB27 NADH-oxidase (Tt27-NOX) catalyzes the oxidation of nicotinamide adenine dinucleotide (NAD(P)H) by reducing molecular oxygen to hydrogen peroxide in a two-electron transfer mechanism. Surprisingly, Tt27-NOX showed significant differences in catalytic properties compared to its counterpart from the strain HB8 (Tt8-NOX), despite a high degree of sequence homology between both variants. The sequence comparison between both enzymes revealed only three divergent amino acid residues at positions 166, 174, and 194. Motivated with these findings, in this work we performed mutagenesis experiments in the former three positions to study the specific role of these residues in the catalytic properties and thermostability of Tt27-NOX. We subjected five mutants, along with the wild-type enzyme, to biochemical characterization and thermal stability studies. As a result, we identified two more active and more thermostable variants than any Tt8-NOX variant reported in the literature. The most active and thermostable variant K166/H174/Y194 retained 90% of its initial activity after 5 h at pH 7 and 80 °C and an increase in melting temperature of 48.3 °C compared with the least active variant K166/R174/Y194 (inactivated after 15 min of incubation). These results, supported by structural analysis and molecular dynamics simulation studies, suggest that Lys at position 166 may stabilize the loop in which His174 is located, increasing thermal stability.
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15
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Meng S, Guo J, Nie K, Tan T, Xu H, Liu L. Chemoenzymatic Synthesis of Fragrance Compounds from Stearic Acid. Chembiochem 2019; 20:2232-2235. [PMID: 30983113 DOI: 10.1002/cbic.201900210] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Indexed: 11/09/2022]
Abstract
Fatty acids are versatile precursors for fuels, fine chemicals, polymers, perfumes, etc. The properties and applications of fatty acid derivatives depend on chain length and on functional groups and their positions. To tailor fatty acids for desired properties, an engineered P450 monooxygenase has been employed here for enhanced selective hydroxylation of fatty acids. After oxidation of the hydroxy groups to the corresponding ketones, Baeyer-Villiger oxidation could be applied to introduce an oxygen atom into the hydrocarbon chains to form esters, which were finally hydrolyzed to afford either hydroxylated fatty acids or dicarboxylic fatty acids. Using this strategy, we have demonstrated that the high-value-added flavors exaltolide and silvanone supra can be synthesized from stearic acid through a hydroxylation/carbonylation/esterification/hydrolysis/lactonization reaction sequence with isolated yields of about 36 % (for ω-1 hydroxylated stearic acid; 100, 60, 80, 75 % yields for the individual reactions, respectively) or 24 % (for ω-2 hydroxylated stearic acid). Ultimately, we obtained 7.91 mg of exaltolide and 13.71 mg of silvanone supra from 284.48 mg stearic acid.
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Affiliation(s)
- Shuaiqi Meng
- Beijing Bioprocess Key Laboratory, Beijing University of Chemical Technology, Beisanhuan EastRoad 15, Beijing, 100029, China
| | - Jia Guo
- State Key Laboratory of Special Functional Waterproof Materials, Beijing Oriental Yuhong Waterproof Technology Co. Ltd, Shunping Road 2, Beijing, 1000123, China
| | - Kaili Nie
- Beijing Bioprocess Key Laboratory, Beijing University of Chemical Technology, Beisanhuan EastRoad 15, Beijing, 100029, China
| | - Tianwei Tan
- Beijing Bioprocess Key Laboratory, Beijing University of Chemical Technology, Beisanhuan EastRoad 15, Beijing, 100029, China
| | - Haijun Xu
- Beijing Bioprocess Key Laboratory, Beijing University of Chemical Technology, Beisanhuan EastRoad 15, Beijing, 100029, China
| | - Luo Liu
- Beijing Bioprocess Key Laboratory, Beijing University of Chemical Technology, Beisanhuan EastRoad 15, Beijing, 100029, China
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16
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Yang J, Bai J, Qu M, Xie B, Yang Q. Biochemical characteristics of a nitroreductase with diverse substrate specificity from Streptomyces mirabilis DUT001. Biotechnol Appl Biochem 2018; 66:33-42. [PMID: 30231196 DOI: 10.1002/bab.1692] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 09/11/2018] [Indexed: 11/09/2022]
Abstract
A nitroreductase-encoded gene from an efficient nitro-reducing bacterium Streptomyces mirabilis DUT001, named snr, was cloned and heterogeneously expressed in Escherichia coli. The purified Streptomyces nitroreductase SNR was a homodimer with an apparent subunit molecular weight of 24 kDa and preferred NADH to NADPH as a cofactor. By enzyme incubation and isothermal calorimetry experiments, flavin mononucleotide (FMN) was found to be the preferred flavin cofactor; the binding process was exothermic and primarily enthalpy driven. The enzyme can reduce multiple nitro compounds and flavins, including antibacterial drug nitrofurazone, priority pollutants 2,4-dinitrotoluene and 2,4,6-trinitrotoluene, as well as key chemical intermediates 3-nitrophthalimide, 4-nitrophthalimide, and 4-nitro-1,8-naphthalic anhydride. Among the substrates tested, the highest activity of kcat(app) /Km(app) (0.234 μM-1 Sec-1 ) was observed for the reduction of FMN. Multiple sequence alignment revealed that the high FMN reduction activity of SNR may be due to the absence of a helix, constituting the entrance to the substrate pocket in other nitroreductases.
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Affiliation(s)
- Jun Yang
- State Key Laboratory of Fine Chemical Engineering and School of Life Science and Biotechnology, Dalian University of Technology, Dalian, People's Republic of China
| | - Jing Bai
- College of Bioscience and Bioengineering, Hebei University of Science & Technology, Hebei, People's Republic of China
| | - Mingbo Qu
- State Key Laboratory of Fine Chemical Engineering and School of Life Science and Biotechnology, Dalian University of Technology, Dalian, People's Republic of China
| | - Bo Xie
- State Key Laboratory of Fine Chemical Engineering and School of Life Science and Biotechnology, Dalian University of Technology, Dalian, People's Republic of China
| | - Qing Yang
- State Key Laboratory of Fine Chemical Engineering and School of Life Science and Biotechnology, Dalian University of Technology, Dalian, People's Republic of China
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17
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Mariyappan P, Kalaiyarasu T, Manju V. Effect of eriodictyol on preneoplastic lesions, oxidative stress and bacterial enzymes in 1,2-dimethyl hydrazine-induced colon carcinogenesis. Toxicol Res (Camb) 2017; 6:678-692. [PMID: 30090535 PMCID: PMC6061826 DOI: 10.1039/c7tx00074j] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Accepted: 06/16/2017] [Indexed: 01/07/2023] Open
Abstract
Eriodictyol, one of the strong flavonoids extracted from Eriodictyon californicum, is known for its antioxidant and anticarcinogenic properties. We estimated the chemopreventive effect of eriodictyol on 1,2 dimethylhydrazine (DMH)-induced experimental colon carcinogenesis in male albino Wistar rats. The rats were randomized into six groups. Our results evaluated the effect of eriodictyol supplementation (200 μg per kg b.w.) on DMH (20 mg per kg b.w)-induced rats (Groups 4-6). The incidence of polyps, aberrant crypt foci (ACF) and the lipid peroxidation levels were significantly decreased as compared to those in the DMH-alone treated rats (Group 2). In eriodictyol-supplemented DMH-treated rats, we observed increased activity of enzymatic and non-enzymatic antioxidants in the circulatory system, liver, and colon. The bacterial enzymes activities of mucosa and faecal were significantly decreased in the group with treatment of eriodictyol on DMH-induced rats. Moreover, in the eriodictyol-supplemented DMH-exposed rats, we observed reduced malignant glands of a histopathological appearance in both liver and colon tissue. Furthermore, we also observed reduced AgNORs counts of eriodictyol supplemented to the DMH-exposed rats. Therefore, we can conclude that eriodictyol can be used as an effective chemopreventive agent against DMH-induced colon carcinogenesis in experimental animal models.
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Affiliation(s)
- P Mariyappan
- Department of Biochemistry , Periyar University , Salem , Tamil Nadu 636011 , India .
| | - T Kalaiyarasu
- Department of Biochemistry , Periyar University , Salem , Tamil Nadu 636011 , India .
| | - V Manju
- Department of Biochemistry , Periyar University , Salem , Tamil Nadu 636011 , India .
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18
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Hoben JP, Lubner CE, Ratzloff MW, Schut GJ, Nguyen DMN, Hempel KW, Adams MWW, King PW, Miller AF. Equilibrium and ultrafast kinetic studies manipulating electron transfer: A short-lived flavin semiquinone is not sufficient for electron bifurcation. J Biol Chem 2017; 292:14039-14049. [PMID: 28615449 DOI: 10.1074/jbc.m117.794214] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 06/11/2017] [Indexed: 11/06/2022] Open
Abstract
Flavin-based electron transfer bifurcation is emerging as a fundamental and powerful mechanism for conservation and deployment of electrochemical energy in enzymatic systems. In this process, a pair of electrons is acquired at intermediate reduction potential (i.e. intermediate reducing power), and each electron is passed to a different acceptor, one with lower and the other with higher reducing power, leading to "bifurcation." It is believed that a strongly reducing semiquinone species is essential for this process, and it is expected that this species should be kinetically short-lived. We now demonstrate that the presence of a short-lived anionic flavin semiquinone (ASQ) is not sufficient to infer the existence of bifurcating activity, although such a species may be necessary for the process. We have used transient absorption spectroscopy to compare the rates and mechanisms of decay of ASQ generated photochemically in bifurcating NADH-dependent ferredoxin-NADP+ oxidoreductase and the non-bifurcating flavoproteins nitroreductase, NADH oxidase, and flavodoxin. We found that different mechanisms dominate ASQ decay in the different protein environments, producing lifetimes ranging over 2 orders of magnitude. Capacity for electron transfer among redox cofactors versus charge recombination with nearby donors can explain the range of ASQ lifetimes that we observe. Our results support a model wherein efficient electron propagation can explain the short lifetime of the ASQ of bifurcating NADH-dependent ferredoxin-NADP+ oxidoreductase I and can be an indication of capacity for electron bifurcation.
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Affiliation(s)
- John P Hoben
- From the Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506
| | | | | | - Gerrit J Schut
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602
| | - Diep M N Nguyen
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602
| | - Karl W Hempel
- From the Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506
| | - Michael W W Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602
| | - Paul W King
- National Renewable Energy Laboratory, Golden, Colorado 80401
| | - Anne-Frances Miller
- From the Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506.
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19
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Pitsawong W, Haynes CA, Koder RL, Rodgers DW, Miller AF. Mechanism-Informed Refinement Reveals Altered Substrate-Binding Mode for Catalytically Competent Nitroreductase. Structure 2017; 25:978-987.e4. [PMID: 28578873 DOI: 10.1016/j.str.2017.05.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 04/02/2017] [Accepted: 05/05/2017] [Indexed: 01/25/2023]
Abstract
Nitroreductase (NR) from Enterobacter cloacae reduces diverse nitroaromatics including herbicides, explosives, and prodrugs, and holds promise for bioremediation, prodrug activation, and enzyme-assisted synthesis. We solved crystal structures of NR complexes with bound substrate or analog for each of its two half-reactions. We complemented these with kinetic isotope effect (KIE) measurements elucidating H-transfer steps essential to each half-reaction. KIEs indicate hydride transfer from NADH to the flavin consistent with our structure of NR with the NADH analog nicotinic acid adenine dinucleotide (NAAD). The KIE on reduction of p-nitrobenzoic acid (p-NBA) also indicates hydride transfer, and requires revision of prior computational mechanisms. Our mechanistic information provided a structural restraint for the orientation of bound substrate, placing the nitro group closer to the flavin N5 in the pocket that binds the amide of NADH. KIEs show that solvent provides a proton, enabling accommodation of different nitro group placements, consistent with the broad repertoire of NR.
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Affiliation(s)
- Warintra Pitsawong
- Department of Chemistry, University of Kentucky, 505 Rose Street, Lexington, KY 40506-0055, USA
| | - Chad A Haynes
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, 741 South Limestone Street, Lexington, KY 40536-0509, USA
| | - Ronald L Koder
- Department of Chemistry, University of Kentucky, 505 Rose Street, Lexington, KY 40506-0055, USA
| | - David W Rodgers
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, 741 South Limestone Street, Lexington, KY 40536-0509, USA.
| | - Anne-Frances Miller
- Department of Chemistry, University of Kentucky, 505 Rose Street, Lexington, KY 40506-0055, USA; Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, 741 South Limestone Street, Lexington, KY 40536-0509, USA.
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20
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Agarwal V, Miles ZD, Winter JM, Eustáquio AS, El Gamal AA, Moore BS. Enzymatic Halogenation and Dehalogenation Reactions: Pervasive and Mechanistically Diverse. Chem Rev 2017; 117:5619-5674. [PMID: 28106994 PMCID: PMC5575885 DOI: 10.1021/acs.chemrev.6b00571] [Citation(s) in RCA: 246] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Naturally produced halogenated compounds are ubiquitous across all domains of life where they perform a multitude of biological functions and adopt a diversity of chemical structures. Accordingly, a diverse collection of enzyme catalysts to install and remove halogens from organic scaffolds has evolved in nature. Accounting for the different chemical properties of the four halogen atoms (fluorine, chlorine, bromine, and iodine) and the diversity and chemical reactivity of their organic substrates, enzymes performing biosynthetic and degradative halogenation chemistry utilize numerous mechanistic strategies involving oxidation, reduction, and substitution. Biosynthetic halogenation reactions range from simple aromatic substitutions to stereoselective C-H functionalizations on remote carbon centers and can initiate the formation of simple to complex ring structures. Dehalogenating enzymes, on the other hand, are best known for removing halogen atoms from man-made organohalogens, yet also function naturally, albeit rarely, in metabolic pathways. This review details the scope and mechanism of nature's halogenation and dehalogenation enzymatic strategies, highlights gaps in our understanding, and posits where new advances in the field might arise in the near future.
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Affiliation(s)
- Vinayak Agarwal
- Center for Oceans and Human Health, Scripps Institution of Oceanography, University of California, San Diego
| | - Zachary D. Miles
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego
| | | | - Alessandra S. Eustáquio
- College of Pharmacy, Department of Medicinal Chemistry & Pharmacognosy and Center for Biomolecular Sciences, University of Illinois at Chicago
| | - Abrahim A. El Gamal
- Center for Oceans and Human Health, Scripps Institution of Oceanography, University of California, San Diego
| | - Bradley S. Moore
- Center for Oceans and Human Health, Scripps Institution of Oceanography, University of California, San Diego
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego
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21
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Huijbers MME, Martínez-Júlvez M, Westphal AH, Delgado-Arciniega E, Medina M, van Berkel WJH. Proline dehydrogenase from Thermus thermophilus does not discriminate between FAD and FMN as cofactor. Sci Rep 2017; 7:43880. [PMID: 28256579 PMCID: PMC5335563 DOI: 10.1038/srep43880] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 01/30/2017] [Indexed: 12/19/2022] Open
Abstract
Flavoenzymes are versatile biocatalysts containing either FAD or FMN as cofactor. FAD often binds to a Rossmann fold, while FMN prefers a TIM-barrel or flavodoxin-like fold. Proline dehydrogenase is denoted as an exception: it possesses a TIM barrel-like fold while binding FAD. Using a riboflavin auxotrophic Escherichia coli strain and maltose-binding protein as solubility tag, we produced the apoprotein of Thermus thermophilus ProDH (MBP-TtProDH). Remarkably, reconstitution with FAD or FMN revealed that MBP-TtProDH has no preference for either of the two prosthetic groups. Kinetic parameters of both holo forms are similar, as are the dissociation constants for FAD and FMN release. Furthermore, we show that the holo form of MBP-TtProDH, as produced in E. coli TOP10 cells, contains about three times more FMN than FAD. In line with this flavin content, the crystal structure of TtProDH variant ΔABC, which lacks helices αA, αB and αC, shows no electron density for an AMP moiety of the cofactor. To the best of our knowledge, this is the first example of a flavoenzyme that does not discriminate between FAD and FMN as cofactor. Therefore, classification of TtProDH as an FAD-binding enzyme should be reconsidered.
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Affiliation(s)
- Mieke M. E. Huijbers
- Laboratory of Biochemistry, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Marta Martínez-Júlvez
- Department of Biochemistry and Molecular Cell Biology and Institute for Biocomputation and Physics of Complex Systems, University of Zaragoza, Pedro Cerbuna 12, 50009, Zaragoza, Spain
| | - Adrie H. Westphal
- Laboratory of Biochemistry, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Estela Delgado-Arciniega
- Laboratory of Biochemistry, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Milagros Medina
- Department of Biochemistry and Molecular Cell Biology and Institute for Biocomputation and Physics of Complex Systems, University of Zaragoza, Pedro Cerbuna 12, 50009, Zaragoza, Spain
| | - Willem J. H. van Berkel
- Laboratory of Biochemistry, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
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22
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Valiauga B, Williams EM, Ackerley DF, Čėnas N. Reduction of quinones and nitroaromatic compounds by Escherichia coli nitroreductase A (NfsA): Characterization of kinetics and substrate specificity. Arch Biochem Biophys 2016; 614:14-22. [PMID: 27986535 DOI: 10.1016/j.abb.2016.12.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 12/09/2016] [Accepted: 12/12/2016] [Indexed: 11/16/2022]
Abstract
NfsA, a major FMN-associated nitroreductase of E. coli, reduces nitroaromatic compounds via consecutive two-electron transfers. NfsA has potential applications in the biodegradation of nitroaromatic environment pollutants, e.g. explosives, and is also of interest for the anticancer strategy gene-directed enzyme prodrug therapy. However, the catalytic mechanism of NfsA is poorly characterized. Here we examined the NADPH-dependent reduction of quinones (n = 16) and nitroaromatic compounds (n = 12) by NfsA. We confirmed a general "ping-pong" reaction scheme, and preliminary rapid reaction studies of the enzyme reduction by NADPH showed that this step is much faster than the steady-state turnover number, i.e., the enzyme turnover is limited by the oxidative half-reaction. The reactivity of nitroaromatic compounds (log kcat/Km) followed a linear dependence on their single-electron reduction potential (E17), indicating a limited role for compound structure or active site flexibility in their reactivity. The reactivity of quinones was lower than that of nitroaromatics having similar E17 values, except for the significantly enhanced reactivity of 2-OH-1,4-naphthoquinones, consistent with observations previously made for the group B nitroreductase of Enterobacter cloacae. We present evidence that the reduction of quinones by NfsA is most consistent with a single-step (H-) hydride transfer mechanism.
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Affiliation(s)
- Benjaminas Valiauga
- Institute of Biochemistry of Vilnius University, Mokslininkų 12, LT-08662 Vilnius, Lithuania
| | - Elsie M Williams
- Victoria University of Wellington, School of Biological Sciences, Kelburn Parade, New Zealand
| | - David F Ackerley
- Victoria University of Wellington, School of Biological Sciences, Kelburn Parade, New Zealand
| | - Narimantas Čėnas
- Institute of Biochemistry of Vilnius University, Mokslininkų 12, LT-08662 Vilnius, Lithuania.
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23
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You X, Li L, Li X, Ma H, Zhang G, Zhang D. A New Tetraphenylethylene-Derived Fluorescent Probe for Nitroreductase Detection and Hypoxic-Tumor-Cell Imaging. Chem Asian J 2016; 11:2918-2923. [PMID: 27534906 DOI: 10.1002/asia.201600945] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Indexed: 11/05/2022]
Abstract
The fluorescence detection of nitroreductase (NTR) and evaluation of the hypoxia status of tumor cells are vital, not only for clinical diagnoses and therapy, but also for biomedical research. Herein, we report the synthesis and application of a new fluorometric "turn-on" probe for the detection of NTR (TPE-NO2 ) that takes advantage of the aggregation-induced emission of tetraphenylethylene. TPE-NO2 can detect NTR at concentrations as low as 5 ng mL-1 in aqueous solution. The detection mechanism relied on the aggregation and deaggregation of tetraphenylethylene molecules. Moreover, this fluorescent probe can be used to monitor the hypoxia status of tumor cells through the detection of endogenous NTR.
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Affiliation(s)
- Xue You
- Beijing National Laboratory for Molecular Sciences, Laboratories of Organic Solids and Analytical Chemistry for Living, Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Lihong Li
- Beijing National Laboratory for Molecular Sciences, Laboratories of Organic Solids and Analytical Chemistry for Living, Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Xiaohua Li
- Beijing National Laboratory for Molecular Sciences, Laboratories of Organic Solids and Analytical Chemistry for Living, Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Huimin Ma
- Beijing National Laboratory for Molecular Sciences, Laboratories of Organic Solids and Analytical Chemistry for Living, Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Guanxin Zhang
- Beijing National Laboratory for Molecular Sciences, Laboratories of Organic Solids and Analytical Chemistry for Living, Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
| | - Deqing Zhang
- Beijing National Laboratory for Molecular Sciences, Laboratories of Organic Solids and Analytical Chemistry for Living, Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China. .,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
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24
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Collins J, Zhang T, Huston S, Sun F, Zhang YHP, Fu J. A Hidden Transhydrogen Activity of a FMN-Bound Diaphorase under Anaerobic Conditions. PLoS One 2016; 11:e0154865. [PMID: 27145082 PMCID: PMC4856307 DOI: 10.1371/journal.pone.0154865] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 04/20/2016] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Redox cofactors of NADH/NADPH participate in many cellular metabolic pathways for facilitating the electron transfer from one molecule to another in redox reactions. Transhydrogenase plays an important role in linking catabolism and anabolism, regulating the ratio of NADH/NADPH in cells. The cytoplasmic transhydrogenases could be useful to engineer synthetic biochemical pathways for the production of high-value chemicals and biofuels. METHODOLOGY/PRINCIPAL FINDINGS A transhydrogenase activity was discovered for a FMN-bound diaphorase (DI) from Geobacillus stearothermophilus under anaerobic conditions. The DI-catalyzed hydride exchange were monitored and characterized between a NAD(P)H and a thio-modified NAD+ analogue. This new function of DI was demonstrated to transfer a hydride from NADPH to NAD+ that was consumed by NAD-specific lactate dehydrogenase and malic dehydrogenase. CONCLUSIONS/SIGNIFICANCE We discover a novel transhydrogenase activity of a FMN-DI by stabilizing the reduced state of FMNH2 under anaerobic conditions. FMN-DI was demonstrated to catalyze the hydride transfer between NADPH and NAD+. In the future, it may be possible to incorporate this FMN-DI into synthetic enzymatic pathways for balancing NADH generation and NADPH consumption for anaerobic production of biofuels and biochemicals.
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Affiliation(s)
- John Collins
- Department of Chemistry, Rutgers University-Camden, Camden, New Jersey 08102, United States of America
| | - Ting Zhang
- Department of Chemistry, Rutgers University-Camden, Camden, New Jersey 08102, United States of America
| | - Scott Huston
- Department of Chemistry, Rutgers University-Camden, Camden, New Jersey 08102, United States of America
| | - Fangfang Sun
- Cell Free Bioinnovations Inc., Blacksburg, Virginia 24060, United States of America
| | - Y.-H. Percival Zhang
- Cell Free Bioinnovations Inc., Blacksburg, Virginia 24060, United States of America
- Department of Biological Systems Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States of America
| | - Jinglin Fu
- Department of Chemistry, Rutgers University-Camden, Camden, New Jersey 08102, United States of America
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, New Jersey 08102, United States of America
- * E-mail:
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Booupathy LK, Venkatachalam S, Natarajan N, Thamaraiselvan R, Arumugam M, Maruthaiveeran Periyasamy B. Chemopreventive effect of myrtenal on bacterial enzyme activity and the development of 1,2-dimethyl hydrazine-induced aberrant crypt foci in Wistar Rats. J Food Drug Anal 2016; 24:206-213. [PMID: 28911405 PMCID: PMC9345433 DOI: 10.1016/j.jfda.2015.07.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 07/05/2015] [Accepted: 07/16/2015] [Indexed: 01/04/2023] Open
Abstract
Colon cancer remains as a serious health problem around the world despite advances in diagnosis and treatment. Dietary fibers are considered to reduce the risk of colon cancer as they are converted to short chain fatty acids by the presence of anaerobic bacteria in the intestine, but imbalanced diet and high fat consumption may promote tumor formation at different sites, including the large bowel via increased bacterial enzymes activity. The present study was conducted to characterize the inhibitory action of myrtenal on bacterial enzymes and aberrant crypt foci (ACF). Experimental colon carcinogenesis induced by 1,2-dimethylhydrazine is histologically, morphologically, and anatomically similar to human colonic epithelial neoplasm. Discrete microscopic mucosal lesions such as ACF and malignant tumors function as important biomarkers in the diagnosis of colon cancer. Methylene blue staining was carried out to visualize the impact of 1,2-dimethylhydrazine and myrtenal. Myrtenal-treated animals showed decreased levels of bacterial enzymes such as β-glucuronidase, β-glucosidase, and mucinase. Characteristic changes in the colon were noticed by inhibiting ACF formation in the colon. In conclusion, treatment with myrtenal provided altered pathophysiological condition in colon cancer-bearing animals with evidence of decreased crypt multiplicity and tumor progression.
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Miletti T, Di Trani J, Jr Levros LC, Mittermaier A. Conformational plasticity surrounding the active site of NADH oxidase from Thermus thermophilus. Protein Sci 2015; 24:1114-28. [PMID: 25970557 PMCID: PMC4500311 DOI: 10.1002/pro.2693] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 04/26/2015] [Indexed: 11/08/2022]
Abstract
Biotechnological applications of enzymes can involve the use of these molecules under nonphysiological conditions. Thus, it is of interest to understand how environmental variables affect protein structure and dynamics and how this ultimately modulates enzyme function. NADH oxidase (NOX) from Thermus thermophilus exemplifies how enzyme activity can be tuned by reaction conditions, such as temperature, cofactor substitution, and the addition of cosolutes. This enzyme catalyzes the oxidation of reduced NAD(P)H to NAD(P)(+) with the concurrent reduction of O2 to H2O2, with relevance to biosensing applications. It is thermophilic, with an optimum temperature of approximately 65°C and sevenfold lower activity at 25°C. Moderate concentrations (≈1M) of urea and other chaotropes increase NOX activity by up to a factor of 2.5 at room temperature. Furthermore, it is a flavoprotein that accepts either FMN or the much larger FAD as cofactor. We have used nuclear magnetic resonance (NMR) titration and (15)N spin relaxation experiments together with isothermal titration calorimetry to study how NOX structure and dynamics are affected by changes in temperature, the addition of urea and the substitution of the FMN cofactor with FAD. The majority of signals from NOX are quite insensitive to changes in temperature, cosolute addition, and cofactor substitution. However, a small cluster of residues surrounding the active site shows significant changes. These residues are implicated in coupling changes in the solution conditions of the enzyme to changes in catalytic activity.
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Affiliation(s)
- Teresa Miletti
- Department of Chemistry, McGill UniversityMontreal, Quebec, H3A 0B8
| | - Justin Di Trani
- Department of Chemistry, McGill UniversityMontreal, Quebec, H3A 0B8
| | - Louis-Charles Jr Levros
- Laboratoire de biologie moléculaire, Département des Sciences Biologiques, Centre BioMed, Université du Québec à MontréalMontréal, Québec, H3C 3P8
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Rocha-Martin J, Acosta A, Guisan JM, López-Gallego F. Immobilizing Systems Biocatalysis for the Selective Oxidation of Glycerol Coupled to In Situ Cofactor Recycling and Hydrogen Peroxide Elimination. ChemCatChem 2015. [DOI: 10.1002/cctc.201500210] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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28
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Transformation pathway of 2,4,6-trinitrotoluene by Escherichia coli nitroreductases and improvement of activity using structure-based mutagenesis. Process Biochem 2015. [DOI: 10.1016/j.procbio.2015.01.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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29
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Park JT, Gómez Ramos LM, Bommarius AS. Engineering towards Nitroreductase Functionality in Ene-Reductase Scaffolds. Chembiochem 2015; 16:811-8. [DOI: 10.1002/cbic.201402667] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Indexed: 11/10/2022]
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Phatarphekar A, Buss JM, Rokita SE. Iodotyrosine deiodinase: a unique flavoprotein present in organisms of diverse phyla. MOLECULAR BIOSYSTEMS 2014; 10:86-92. [PMID: 24153409 DOI: 10.1039/c3mb70398c] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Iodide is required for thyroid hormone synthesis in mammals and other vertebrates. The role of both iodide and iodinated tyrosine derivatives is currently unknown in lower organisms, yet the presence of a key enzyme in iodide conservation, iodotyrosine deiodinase (IYD), is suggested by genomic data from a wide range of multicellular organisms as well as some bacteria. A representative set of these genes has now been expressed, and the resulting enzymes all catalyze reductive deiodination of diiodotyrosine with kcat/Km values within a single order of magnitude. This implies a physiological presence of iodotyrosines (or related halotyrosines) and a physiological role for their turnover. At least for Metazoa, IYD should provide a new marker for tracing the evolutionary development of iodinated amino acids as regulatory signals through the tree of life.
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Affiliation(s)
- Abhishek Phatarphekar
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA.
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31
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H(2)O(2) production in species of the Lactobacillus acidophilus group: a central role for a novel NADH-dependent flavin reductase. Appl Environ Microbiol 2014; 80:2229-39. [PMID: 24487531 DOI: 10.1128/aem.04272-13] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hydrogen peroxide production is a well-known trait of many bacterial species associated with the human body. In the presence of oxygen, the probiotic lactic acid bacterium Lactobacillus johnsonii NCC 533 excretes up to 1 mM H(2)O(2), inducing growth stagnation and cell death. Disruption of genes commonly assumed to be involved in H(2)O(2) production (e.g., pyruvate oxidase, NADH oxidase, and lactate oxidase) did not affect this. Here we describe the purification of a novel NADH-dependent flavin reductase encoded by two highly similar genes (LJ_0548 and LJ_0549) that are conserved in lactobacilli belonging to the Lactobacillus acidophilus group. The genes are predicted to encode two 20-kDa proteins containing flavin mononucleotide (FMN) reductase conserved domains. Reductase activity requires FMN, flavin adenine dinucleotide (FAD), or riboflavin and is specific for NADH and not NADPH. The Km for FMN is 30 ± 8 μM, in accordance with its proposed in vivo role in H(2)O(2) production. Deletion of the encoding genes in L. johnsonii led to a 40-fold reduction of hydrogen peroxide formation. H(2)O(2) production in this mutant could only be restored by in trans complementation of both genes. Our work identifies a novel, conserved NADH-dependent flavin reductase that is prominently involved in H(2)O(2) production in L. johnsonii.
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Yuan J, Xu YQ, Zhou NN, Wang R, Qian XH, Xu YF. A highly selective turn-on fluorescent probe based on semi-cyanine for the detection of nitroreductase and hypoxic tumor cell imaging. RSC Adv 2014. [DOI: 10.1039/c4ra10044a] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
A selective turn-on fluorescent probe based on semi-cyanine for the detection of nitroreductase (NTR) and hypoxia was designed and synthesized.
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Affiliation(s)
- Jun Yuan
- Shanghai Key Laboratory of Chemical Biology
- State Key Laboratory of Bioreactor Engineering
- School of Pharmacy
- East China University of Science and Technology
- Shanghai 200237, China
| | - Yu-Qiong Xu
- Shanghai Key Laboratory of Chemical Biology
- State Key Laboratory of Bioreactor Engineering
- School of Pharmacy
- East China University of Science and Technology
- Shanghai 200237, China
| | - Nan-Nan Zhou
- Shanghai Key Laboratory of New Drug Design
- School of Pharmacy
- East China University of Science and Technology
- Shanghai 200237, China
| | - Rui Wang
- Shanghai Key Laboratory of New Drug Design
- School of Pharmacy
- East China University of Science and Technology
- Shanghai 200237, China
| | - Xu-Hong Qian
- Shanghai Key Laboratory of Chemical Biology
- State Key Laboratory of Bioreactor Engineering
- School of Pharmacy
- East China University of Science and Technology
- Shanghai 200237, China
| | - Yu-Fang Xu
- Shanghai Key Laboratory of Chemical Biology
- State Key Laboratory of Bioreactor Engineering
- School of Pharmacy
- East China University of Science and Technology
- Shanghai 200237, China
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Anusevičius Ž, Misevičienė L, Šarlauskas J, Rouhier N, Jacquot JP, Čėnas N. Quinone- and nitroreductase reactions of Thermotoga maritima peroxiredoxin-nitroreductase hybrid enzyme. Arch Biochem Biophys 2012; 528:50-6. [PMID: 22982531 DOI: 10.1016/j.abb.2012.08.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 08/29/2012] [Accepted: 08/31/2012] [Indexed: 10/27/2022]
Abstract
Thermotoga maritima peroxiredoxin-nitroreductase hybrid enzyme (Prx-NR) consists of a FMN-containing nitroreductase (NR) domain fused to a peroxiredoxin (Prx) domain. These domains seem to function independently as no electron transfer occurs between them. The reduction of quinones and nitroaromatics by NR proceeded in a two-electron manner, and follows a 'ping-pong' scheme with sometimes pronounced inhibition by quinone substrate. The comparison of steady- and presteady-state kinetic data shows that in most cases, the oxidative half-reaction may be rate-limiting in the catalytic cycle of NR. The enzyme was inhibited by dicumarol, a classical inhibitor of oxygen-insensitive nitroreductases. The reduction of quinones and nitroaromatic compounds by Prx-NR was characterized by the linear dependence of their reactivity (logk(cat)/K(m)) on their single-electron reduction potentials E(7)(1), while the reactivity of quinones markedly exceeded the one with nitroaromatics. It shows that NR lacks the specificity for the particular structure of these oxidants, except their single-electron accepting potency and the rate of electron self-exchange. It points to the possibility of a single-electron transfer step in a net two-electron reduction of quinones and nitroaromatics by T. maritima Prx-NR, and to a significant diversity of the structures of flavoenzymes which may perform the two-electron reduction of quinones and nitroaromatics.
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Affiliation(s)
- Žilvinas Anusevičius
- Institute of Biochemistry of Vilnius University, Mokslininkų 12, LT-08662 Vilnius, Lithuania
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34
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Buss JM, McTamney PM, Rokita SE. Expression of a soluble form of iodotyrosine deiodinase for active site characterization by engineering the native membrane protein from Mus musculus. Protein Sci 2012; 21:351-61. [PMID: 22238141 DOI: 10.1002/pro.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Reductive deiodination is critical for thyroid function and represents an unusual exception to the more common oxidative and hydrolytic mechanisms of dehalogenation in mammals. Studies on the reductive processes have been limited by a lack of convenient methods for heterologous expression of the appropriate proteins in large scale. The enzyme responsible for iodide salvage in the thyroid, iodotyrosine deodinase, is now readily generated after engineering its gene from Mus musculus. High expression of a truncated derivative lacking the membrane domain at its N-terminal was observed in Sf9 cells, whereas expression in Pichia pastoris remained low despite codon optimization. Ultimately, the desired expression in Escherichia coli was achieved after replacing the two conserved Cys residues of the deiodinase with Ala and fusing the resulting protein to thioredoxin. This final construct provided abundant enzyme for crystallography and mutagenesis. Utility of the E. coli system was demonstrated by examining a set of active site residues critical for binding to the zwitterionic portion of substrate.
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Affiliation(s)
- Jennifer M Buss
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742-2021, USA
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35
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Yu TY, Mok KC, Kennedy KJ, Valton J, Anderson KS, Walker GC, Taga ME. Active site residues critical for flavin binding and 5,6-dimethylbenzimidazole biosynthesis in the flavin destructase enzyme BluB. Protein Sci 2012; 21:839-49. [PMID: 22528544 DOI: 10.1002/pro.2068] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 03/07/2012] [Accepted: 03/19/2012] [Indexed: 12/14/2022]
Abstract
The "flavin destructase" enzyme BluB catalyzes the unprecedented conversion of flavin mononucleotide (FMN) to 5,6-dimethylbenzimidazole (DMB), a component of vitamin B(12). Because of its unusual chemistry, the mechanism of this transformation has remained elusive. This study reports the identification of 12 mutant forms of BluB that have severely reduced catalytic function, though most retain the ability to bind flavin. The "flavin destructase" BluB is an unusual enzyme that fragments the flavin cofactor FMNH(2) in the presence of oxygen to produce 5,6-dimethylbenzimidazole (DMB), the lower axial ligand of vitamin B(12) (cobalamin). Despite the similarities in sequence and structure between BluB and the nitroreductase and flavin oxidoreductase enzyme families, BluB is the only enzyme known to fragment a flavin isoalloxazine ring. To explore the catalytic residues involved in this unusual reaction, mutants of BluB impaired in DMB biosynthesis were identified in a genetic screen in the bacterium Sinorhizobium meliloti. Of the 16 unique point mutations identified in the screen, the majority were located in conserved residues in the active site or in the unique "lid" domain proposed to shield the active site from solvent. Steady-state enzyme assays of 12 purified mutant proteins showed a significant reduction in DMB synthesis in all of the mutants, with eight completely defective in DMB production. Ten of these mutants have weaker binding affinities for both oxidized and reduced FMN, though only two have a significant effect on complex stability. These results implicate several conserved residues in BluB's unique ability to fragment FMNH(2) and demonstrate the sensitivity of BluB's active site to structural perturbations. This work lays the foundation for mechanistic studies of this enzyme and further advances our understanding of the structure-function relationship of BluB.
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Affiliation(s)
- Ta-Yi Yu
- Department of Plant & Microbial Biology, University of California, Berkeley, California 94720-3102, USA
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36
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Merkley ED, Daggett V, Parson WW. A temperature-dependent conformational change of NADH oxidase from Thermus thermophilus HB8. Proteins 2011; 80:546-55. [PMID: 22081476 DOI: 10.1002/prot.23219] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 10/04/2011] [Accepted: 10/07/2011] [Indexed: 11/10/2022]
Abstract
Using molecular dynamics simulations and steady-state fluorescence spectroscopy, we have identified a conformational change in the active site of a thermophilic flavoenzyme, NADH oxidase from Thermus thermophilus HB8 (NOX). The enzyme's far-UV circular dichroism spectrum, intrinsic tryptophan fluorescence, and apparent molecular weight measured by dynamic light scattering varied little between 25 and 75°C. However, the fluorescence of the tightly bound FAD cofactor increased approximately fourfold over this temperature range. This effect appears not to be due to aggregation, unfolding, cofactor dissociation, or changes in quaternary structure. We therefore attribute the change in flavin fluorescence to a temperature-dependent conformational change involving the NOX active site. Molecular dynamics simulations and the effects of mutating aromatic residues near the flavin suggest that the change in fluorescence results from a decrease in quenching by electron transfer from tyrosine 137 to the flavin.
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Affiliation(s)
- Eric D Merkley
- Department of Biochemistry, University of Washington, Seattle, Washington
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37
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Rocha-Martín J, Vega D, Bolivar JM, Godoy CA, Hidalgo A, Berenguer J, Guisán JM, López-Gallego F. New biotechnological perspectives of a NADH oxidase variant from Thermus thermophilus HB27 as NAD+-recycling enzyme. BMC Biotechnol 2011; 11:101. [PMID: 22053761 PMCID: PMC3238333 DOI: 10.1186/1472-6750-11-101] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Accepted: 11/03/2011] [Indexed: 11/10/2022] Open
Abstract
Background The number of biotransformations that use nicotinamide recycling systems is exponentially growing. For this reason one of the current challenges in biocatalysis is to develop and optimize more simple and efficient cofactor recycling systems. One promising approach to regenerate NAD+ pools is the use of NADH-oxidases that reduce oxygen to hydrogen peroxide while oxidizing NADH to NAD+. This class of enzymes may be applied to asymmetric reduction of prochiral substrates in order to obtain enantiopure compounds. Results The NADH-oxidase (NOX) presented here is a flavoenzyme which needs exogenous FAD or FMN to reach its maximum velocity. Interestingly, this enzyme is 6-fold hyperactivated by incubation at high temperatures (80°C) under limiting concentrations of flavin cofactor, a change that remains stable even at low temperatures (37°C). The hyperactivated form presented a high specific activity (37.5 U/mg) at low temperatures despite isolation from a thermophile source. Immobilization of NOX onto agarose activated with glyoxyl groups yielded the most stable enzyme preparation (6-fold more stable than the hyperactivated soluble enzyme). The immobilized derivative was able to be reactivated under physiological conditions after inactivation by high solvent concentrations. The inactivation/reactivation cycle could be repeated at least three times, recovering full NOX activity in all cases after the reactivation step. This immobilized catalyst is presented as a recycling partner for a thermophile alcohol dehydrogenase in order to perform the kinetic resolution secondary alcohols. Conclusion We have designed, developed and characterized a heterogeneous and robust biocatalyst which has been used as recycling partner in the kinetic resolution of rac-1-phenylethanol. The high stability along with its capability to be reactivated makes this biocatalyst highly re-useable for cofactor recycling in redox biotransformations.
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Affiliation(s)
- Javier Rocha-Martín
- Departamento de Biocatálisis, Instituto de Catálisis y Petroleoquímica, Cantoblanco, Madrid, Spain.
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38
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Rehan AM, Bashiri G, Paterson NG, Baker EN, Squire CJ. Cloning, expression, purification, crystallization and preliminary X-ray studies of the C-terminal domain of Rv3262 (FbiB) from Mycobacterium tuberculosis. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:1274-7. [PMID: 22102046 PMCID: PMC3212381 DOI: 10.1107/s1744309111028958] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Accepted: 07/18/2011] [Indexed: 11/11/2022]
Abstract
During cofactor F(420) biosynthesis, the enzyme F(420)-γ-glutamyl ligase (FbiB) catalyzes the addition of γ-linked L-glutamate residues to form polyglutamylated F(420) derivatives. In Mycobacterium tuberculosis, Rv3262 (FbiB) consists of two domains: an N-terminal domain from the F(420) ligase superfamily and a C-terminal domain with sequence similarity to nitro-FMN reductase superfamily proteins. To characterize the role of the C-terminal domain of FbiB in polyglutamyl ligation, it has been purified and crystallized in an apo form. The crystals diffracted to 2.0 Å resolution using a synchrotron source and belonged to the tetragonal space group P4(1)2(1)2 (or P4(3)2(1)2), with unit-cell parameters a = b = 136.6, c = 101.7 Å, α = β = γ = 90°.
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Affiliation(s)
- Aisyah M Rehan
- Structural Biology Laboratory, School of Biological Sciences, The University of Auckland, Auckland, New Zealand.
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39
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Miletti T, Farber PJ, Mittermaier A. Active site dynamics in NADH oxidase from Thermus thermophilus studied by NMR spin relaxation. JOURNAL OF BIOMOLECULAR NMR 2011; 51:71-82. [PMID: 21947916 DOI: 10.1007/s10858-011-9542-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Accepted: 06/28/2011] [Indexed: 05/31/2023]
Abstract
We have characterized the backbone dynamics of NADH oxidase from Thermus thermophilus (NOX) using a recently-developed suite of NMR experiments designed to isolate exchange broadening, together with (15)N R (1), R (1ρ ), and {(1)H}-(15)N steady-state NOE relaxation measurements performed at 11.7 and 18.8 T. NOX is a 54 kDa homodimeric enzyme that belongs to a family of structurally homologous flavin reductases and nitroreductases with many potential biotechnology applications. Prior studies have suggested that flexibility is involved in the catalytic mechanism of the enzyme. The active site residue W47 was previously identified as being particularly important, as its level of solvent exposure correlates with enzyme activity, and it was observed to undergo "gating" motions in computer simulations. The NMR data are consistent with these findings. Signals from W47 are dynamically broadened beyond detection and several other residues in the active site have significant R ( ex ) contributions to transverse relaxation rates. In addition, the backbone of S193, whose side chain hydroxyl proton hydrogen bonds directly with the FMN cofactor, exhibits extensive mobility on the ns-ps timescale. We hypothesize that these motions may facilitate structural rearrangements of the active site that allow NOX to accept both FMN and FAD as cofactors.
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Affiliation(s)
- Teresa Miletti
- Department of Chemistry, McGill University, Montreal, QC H3A 2K6, Canada
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40
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41
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Cortial S, Chaignon P, Iorga BI, Aymerich S, Truan G, Gueguen-Chaignon V, Meyer P, Moréra S, Ouazzani J. NADH oxidase activity of Bacillus subtilis nitroreductase NfrA1: insight into its biological role. FEBS Lett 2010; 584:3916-22. [PMID: 20727352 DOI: 10.1016/j.febslet.2010.08.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 08/06/2010] [Accepted: 08/12/2010] [Indexed: 10/19/2022]
Abstract
NfrA1 nitroreductase from the Gram-positive bacterium Bacillus subtilis is a member of the NAD(P)H/FMN oxidoreductase family. Here, we investigated the reactivity, the structure and kinetics of NfrA1, which could provide insight into the unclear biological role of this enzyme. We could show that NfrA1 possesses an NADH oxidase activity that leads to high concentrations of oxygen peroxide and an NAD(+) degrading activity leading to free nicotinamide. Finally, we showed that NfrA1 is able to rapidly scavenge H(2)O(2) produced during the oxidative process or added exogenously.
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Affiliation(s)
- Sylvie Cortial
- Institut de Chimie des Substances Naturelles (ICSN), CNRS UPR 2301, Gif-sur-Yvette, France
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42
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Tóth K, Sedlák E, Musatov A, Žoldák G. Activity of NADH oxidase from Thermus thermophilus in water/alcohol binary mixtures is limited by the stability of quaternary structure. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/j.molcatb.2010.02.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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43
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Merkley ED, Parson WW, Daggett V. Temperature dependence of the flexibility of thermophilic and mesophilic flavoenzymes of the nitroreductase fold. Protein Eng Des Sel 2010; 23:327-36. [PMID: 20083491 PMCID: PMC2851445 DOI: 10.1093/protein/gzp090] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 12/17/2009] [Accepted: 12/18/2009] [Indexed: 11/13/2022] Open
Abstract
A widely held hypothesis regarding the thermostability of thermophilic proteins states asserts that, at any given temperature, thermophilic proteins are more rigid than their mesophilic counterparts. Many experimental and computational studies have addressed this question with conflicting results. Here, we compare two homologous enzymes, one mesophilic (Escherichia coli FMN-dependent nitroreductase; NTR) and one thermophilic (Thermus thermophilus NADH oxidase; NOX), by multiple molecular dynamics simulations at temperatures from 5 to 100 degrees C. We find that the global rigidity/flexibility of the two proteins, assessed by a variety of metrics, is similar on the time scale of our simulations. However, the thermophilic enzyme retains its native conformation to a much greater degree at high temperature than does the mesophilic enzyme, both globally and within the active site. The simulations identify the helix F-helix G 'arm' as the region with the greatest difference in loss of native contacts between the two proteins with increasing temperature. In particular, a network of electrostatic interactions holds helix F to the body of the protein in the thermophilic protein, and this network is absent in the mesophilic counterpart.
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Affiliation(s)
- Eric D. Merkley
- Department of Biochemistry, University of Washington, Box 357350, Seattle, Washington 98195-7350, USA
| | - William W. Parson
- Department of Biochemistry, University of Washington, Box 357350, Seattle, Washington 98195-7350, USA
| | - Valerie Daggett
- Department of Biochemistry, University of Washington, Box 357350, Seattle, Washington 98195-7350, USA
- Department of Bioengineering, University of Washington, Box 355061, Seattle, WA 98195-5061, USA
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Jia B, Lee S, Pham BP, Cho YS, Yang JK, Byeon HS, Kim JC, Cheong GW. An archaeal NADH oxidase causes damage to both proteins and nucleic acids under oxidative stress. Mol Cells 2010; 29:363-71. [PMID: 20213313 DOI: 10.1007/s10059-010-0045-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Revised: 12/18/2009] [Accepted: 12/23/2009] [Indexed: 10/19/2022] Open
Abstract
NADH oxidases (NOXs) catalyze the two-electron reduction of oxygen to H2O2 or four-electron reduction of oxygen to H2O. In this report, we show that an NADH oxidase from Thermococcus profundus (NOXtp) displays two forms: a native dimeric protein under physiological conditions and an oxidized hexameric form under oxidative stress. Native NOXtp displays high NADH oxidase activity, and oxidized NOXtp can accelerate the aggregation of partially unfolded proteins. The aggregates formed by NOXtp have characteristics similar to beta-amyloid and Lewy bodies in neurodegenerative diseases, including an increase of beta-sheet content. Oxidized NOXtp can also bind nucleic acids and cause their degradation by oxidizing NADH to produce H2O2. Furthermore, Escherichia coli cells expressing NOXtp are less viable than cells not expressing NOXtp after treatment with H2O2. As NOXtp shares similar features with eukaryotic cell death isozymes and life may have originated from hyperthermophiles, we suggest that NOXtp may be an ancestor of cell death proteins.
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MESH Headings
- Archaeal Proteins/chemistry
- Archaeal Proteins/metabolism
- Archaeal Proteins/ultrastructure
- Blotting, Western
- DNA Damage
- DNA, Archaeal/genetics
- DNA, Archaeal/metabolism
- Electrophoresis, Polyacrylamide Gel
- Escherichia coli/genetics
- Escherichia coli/growth & development
- Hydrogen Peroxide/metabolism
- Hydrogen Peroxide/pharmacology
- Microbial Viability/genetics
- Microscopy, Electron
- Multienzyme Complexes/chemistry
- Multienzyme Complexes/metabolism
- Multienzyme Complexes/ultrastructure
- NADH, NADPH Oxidoreductases/chemistry
- NADH, NADPH Oxidoreductases/metabolism
- NADH, NADPH Oxidoreductases/ultrastructure
- Oxidation-Reduction
- Oxidative Stress
- Protein Conformation/drug effects
- Protein Multimerization
- RNA, Archaeal/genetics
- RNA, Archaeal/metabolism
- Temperature
- Thermococcus/enzymology
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Affiliation(s)
- Baolei Jia
- Division of Applied Life Sciences (Brain Korea 21 Program), Gyeongsang National University, Jinju, 660-701, Korea
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45
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Koh JU, Chung HJ, Chang WY, Tanokura M, Kong KH. Discovery and Characterization of a Thermostable NADH Oxidase from Pyrococcus horikoshii OT3. B KOREAN CHEM SOC 2009. [DOI: 10.5012/bkcs.2009.30.12.2984] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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46
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Thomas SR, McTamney PM, Adler JM, Laronde-Leblanc N, Rokita SE. Crystal structure of iodotyrosine deiodinase, a novel flavoprotein responsible for iodide salvage in thyroid glands. J Biol Chem 2009; 284:19659-67. [PMID: 19436071 DOI: 10.1074/jbc.m109.013458] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The flavoprotein iodotyrosine deiodinase (IYD) salvages iodide from mono- and diiodotyrosine formed during the biosynthesis of the thyroid hormone thyroxine. Expression of a soluble domain of this membrane-bound enzyme provided sufficient material for crystallization and characterization by x-ray diffraction. The structures of IYD and two co-crystals containing substrates, mono- and diiodotyrosine, alternatively, were solved at resolutions of 2.0, 2.45, and 2.6 A, respectively. The structure of IYD is homologous to others in the NADH oxidase/flavin reductase superfamily, but the position of the active site lid in IYD defines a new subfamily within this group that includes BluB, an enzyme associated with vitamin B(12) biosynthesis. IYD and BluB also share key interactions involving their bound flavin mononucleotide that suggest a unique catalytic behavior within the superfamily. Substrate coordination to IYD induces formation of an additional helix and coil that act as an active site lid to shield the resulting substrate.flavin complex from solvent. This complex is stabilized by aromatic stacking and extensive hydrogen bonding between the substrate and flavin. The carbon-iodine bond of the substrate is positioned directly over the C-4a/N-5 region of the flavin to promote electron transfer. These structures now also provide a molecular basis for understanding thyroid disease based on mutations of IYD.
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Affiliation(s)
- Seth R Thomas
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, Maryland 20742, USA
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47
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Jia B, Park SC, Lee S, Pham BP, Yu R, Le TL, Han SW, Yang JK, Choi MS, Baumeister W, Cheong GW. Hexameric ring structure of a thermophilic archaeon NADH oxidase that produces predominantly H2O. FEBS J 2008; 275:5355-66. [PMID: 18959761 DOI: 10.1111/j.1742-4658.2008.06665.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
An NADH oxidase (NOX) was cloned from the genome of Thermococcus profundus (NOXtp) by genome walking, and the encoded protein was purified to homogeneity after expression in Escherichia coli. Subsequent analyses showed that it is an FAD-containing protein with a subunit molecular mass of 49 kDa that exists as a hexamer with a native molecular mass of 300 kDa. A ring-shaped hexameric form was revealed by electron microscopic and image processing analyses. NOXtp catalyzed the oxidization of NADH and NADPH and predominantly converted O(2) to H(2)O, but not to H(2)O(2), as in the case of most other NOX enzymes. To our knowledge, this is the first example of a NOX that can produce H(2)O predominantly in a thermophilic organism. As an enzyme with two cysteine residues, NOXtp contains a cysteinyl redox center at Cys45 in addition to FAD. Mutant analysis suggests that Cys45 in NOXtp plays a key role in the four-electron reduction of O(2) to H(2)O, but not in the two-electron reduction of O(2) to H(2)O(2).
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Affiliation(s)
- Baolei Jia
- Division of Applied Life Sciences (BK21 Program), Gyeongsang National University, Jinju, Korea
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48
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Thiele B, Rieder O, Jehmlich N, von Bergen M, Müller M, Boll M. Aromatizing cyclohexa-1,5-diene-1-carbonyl-coenzyme A oxidase. Characterization and its role in anaerobic aromatic metabolism. J Biol Chem 2008; 283:20713-21. [PMID: 18505724 DOI: 10.1074/jbc.m802841200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Benzoyl-CoA reductases (BCRs) are key enzymes of anaerobic aromatic metabolism in facultatively anaerobic bacteria. The highly oxygen-sensitive enzymes catalyze the ATP-dependent reductive de-aromatization of the substrate, yielding cyclohexa-1,5-diene-1-carbonyl-CoA (1,5-dienoyl-CoA). In extracts from anaerobically grown denitrifying Thauera aromatica, we detected a benzoate-induced, benzoyl-CoA-forming, 1,5-dienoyl-CoA:acceptor oxidoreductase activity. This activity co-purified with BCR but could be partially separated from it by hydroxyapatite chromatography. After activity staining on native gels, a monomeric protein with a subunit molecular weight of M(r) 76,000 was identified. Mass spectrometric analysis of tryptic digests identified peptides from NADH oxidases/2,4-dienoyl-CoA reductases/"old yellow" enzymes. The UV-visible spectrum of the enriched enzyme suggested the presence of flavin and Fe/S-cofactors, and it was bleached upon the addition of 1,5-dienoyl-CoA. The enzyme had a high affinity for dioxygen as electron acceptor (K(m) = 10 microm) and therefore is referred to as 1,5-dienoyl-CoA oxidase (DCO). The likely product formed from dioxygen reduction was H(2)O. DCO was highly specific for 1,5-dienoyl-CoA (K(m) = 27 microm). The initial rate of DCO followed a Nernst curve with half-maximal activity at +10 mV. We propose that DCO provides protection for the extremely oxygen-sensitive BCR enzyme when the bacterium degrades aromatic compounds at the edge of steep oxygen gradients. The redox-dependent switch in DCO guarantees that DCO is only active during oxidative stress and circumvents futile de-aromatization/re-aromatization reactions catalyzed by BCR and DCO.
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Affiliation(s)
- Bärbel Thiele
- Institute of Biochemistry, University of Leipzig, Brüderstrasse 34, Leipzig, Germany
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49
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Moreno JC, Klootwijk W, van Toor H, Pinto G, D'Alessandro M, Lèger A, Goudie D, Polak M, Grüters A, Visser TJ. Mutations in the iodotyrosine deiodinase gene and hypothyroidism. N Engl J Med 2008; 358:1811-8. [PMID: 18434651 DOI: 10.1056/nejmoa0706819] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
DEHAL1 has been identified as the gene encoding iodotyrosine deiodinase in the thyroid, where it controls the reuse of iodide for thyroid hormone synthesis. We screened patients with hypothyroidism who had features suggestive of an iodotyrosine deiodinase defect for mutations in DEHAL1. Two missense mutations and a deletion of three base pairs were identified in four patients from three unrelated families; all the patients had a dramatic reduction of in vitro activity of iodotyrosine deiodinase. Patients had severe goitrous hypothyroidism, which was evident in infancy and childhood. Two patients had cognitive deficits due to late diagnosis and treatment. Thus, mutations in DEHAL1 led to a deficiency in iodotyrosine deiodinase in these patients. Because infants with DEHAL1 defects may have normal thyroid function at birth, they may be missed by neonatal screening programs for congenital hypothyroidism.
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Affiliation(s)
- José C Moreno
- Department of Internal Medicine, Erasmus Medical Center, Erasmus University, Rotterdam, The Netherlands.
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50
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Tóth K, Sedlák E, Sprinzl M, Zoldák G. Flexibility and enzyme activity of NADH oxidase from Thermus thermophilus in the presence of monovalent cations of Hofmeister series. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:789-95. [PMID: 18339331 DOI: 10.1016/j.bbapap.2008.01.022] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2007] [Revised: 01/26/2008] [Accepted: 01/29/2008] [Indexed: 11/25/2022]
Abstract
Recently, we have shown that anions of Hofmeister series affect the enzyme activity through modulation of flexibility of its active site. The enzyme activity vs. anion position in Hofmeister series showed an unusual bell-shaped dependence. In the present work, six monovalent cations (Na(+), Gdm(+), NH(4)(+), Li(+), K(+) and Cs(+)) of Hofmeister series with chloride as a counterion have been studied in relation to activity and stability of flavoprotein NADH oxidase from Thermus thermophilus (NOX). With the exception of strongly chaotropic guanidinium cation, cations are significantly less effective in promoting the Hofmeister effect than anions mainly due to repulsive interactions of positive charges around the active site. Thermal denaturations of NOX reveal unfavorable electrostatic interaction at the protein surface that may be shielded to different extent by salts. Michaelis-Menten constants for NADH, accessibility of the active site as reflected by Stern-Volmer constants and activity of NOX at high cation concentrations (1-2 M) show bell-shaped dependences on cation position in Hofmeister series. Our analysis indicates that in the presence of kosmotropic cations the enzyme is more stable and possibly more rigid than in the presence of chaotropic cations. Molecular dynamic (MD) simulations of NOX showed that active site switches between open and closed conformations [J. Hritz, G. Zoldak, E. Sedlak, Cofactor assisted gating mechanism in the active site of NADH oxidase from Thermus thermophilus, Proteins 64 (2006) 465-476]. Enzyme activity, as well as substrate binding, can be regulated by the salt mediated perturbation of the balance between open and closed forms. We propose that compensating effect of accessibility and flexibility of the enzyme active site leads to bell-shaped dependence of the investigated parameters.
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Affiliation(s)
- Kamil Tóth
- Department of Biochemistry, Faculty of Sciences P. J. Safárik University, Kosice, Slovakia
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