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Wang B, Wang Y, Zhang Z, Wen X, Xi Z. Insight into the Role of an α-Helix Cluster in Protoporphyrinogen IX Oxidase. Biochemistry 2024. [PMID: 38285491 DOI: 10.1021/acs.biochem.3c00508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2024]
Abstract
Protoporphyrinogen IX oxidase (PPO) is the last common enzyme in chlorophyll and heme biosynthesis pathways. In humans, point mutations on PPO are responsible for the dominantly inherited disorder disease variegate porphyria (VP). It is found that several VP-causing mutation sites are located on an α-helix cluster (consisting of α-5, α-6, and α-7 helix, named the G169 helix cluster) of human PPO, although these mutation sites are outside the active site of the human PPO. In this work, we investigated the role of the G169 helix cluster via site-directed mutagenesis, enzymatic kinetics, and computational studies. Kinetic studies showed that mutations on the G169 helix cluster affect the activity of PPO. The MD simulation showed that mutations on the G169 helix cluster reduced the activity of PPO by affecting the proper orientation of substrate protoporphyrinogen within the active site of PPO and possibly the dipole moment of the G169 helix cluster. Moreover, the mutation abolished the interaction between the mutated site and other residues, thus affecting the secondary structure and hydrogen bond interactions within the G169 helix cluster. These results indicated that the integrity of the G169 helix cluster is important for the stabilization of protoporphyrinogen within the active site of PPO to facilitate the interaction between protoporphyrinogen and cofactor FAD and provide a proper electrostatic environment for the activity of PPO. Our result provides new insight into understanding the relationship between the structure and function of PPO.
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Affiliation(s)
- Baifan Wang
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Yiban Wang
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Zijuan Zhang
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Xin Wen
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Zhen Xi
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin 300071, China
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To-Figueras J. [Biosynthesis of heme and the porphyrias]. Med Clin (Barc) 2023; 159 Suppl 1:S1-S7. [PMID: 37827890 DOI: 10.1016/j.medcli.2023.04.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 03/29/2023] [Accepted: 04/18/2023] [Indexed: 10/14/2023]
Affiliation(s)
- Jordi To-Figueras
- Servicio de Bioquímica y Genética Molecular, Hospital Clínic, Universitat de Barcelona, Barcelona, España.
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The Interaction of Hemin, a Porphyrin Derivative, with the Purified Rat Brain 2-Oxoglutarate Carrier. Biomolecules 2021; 11:biom11081175. [PMID: 34439841 PMCID: PMC8393474 DOI: 10.3390/biom11081175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 08/02/2021] [Accepted: 08/03/2021] [Indexed: 12/26/2022] Open
Abstract
The mitochondrial 2-oxoglutarate carrier (OGC), isolated and purified from rat brain mitochondria, was reconstituted into proteoliposomes to study the interaction with hemin, a porphyrin derivative, which may result from the breakdown of heme-containing proteins and plays a key role in several metabolic pathways. By kinetic approaches, on the basis of the single binding centre gated pore mechanism, we analyzed the effect of hemin on the transport rate of OGC in uptake and efflux experiments in proteoliposomes reconstituted in the presence of the substrate 2-oxoglutarate. Overall, our experimental data fit the hypothesis that hemin operates a competitive inhibition in the 0.5-10 µM concentration range. As a consequence of the OGC inhibition, the malate/aspartate shuttle might be impaired, causing an alteration of mitochondrial function. Hence, considering that the metabolism of porphyrins implies both cytoplasmic and mitochondrial processes, OGC may participate in the regulation of porphyrin derivatives availability and the related metabolic pathways that depend on them (such as oxidative phosphorylation and apoptosis). For the sake of clarity, a simplified model based on induced-fit molecular docking supported the in vitro transport assays findings that hemin was as good as 2-oxoglutarate to bind the carrier by engaging specific ionic hydrogen bond interactions with a number of key residues known for participating in the similarly located mitochondrial carrier substrate binding site.
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Wang B, Zhang Z, Zhu H, Niu C, Wen X, Xi Z. The hydrogen bonding network involved Arg59 in human protoporphyrinogen IX oxidase is essential for enzyme activity. Biochem Biophys Res Commun 2021; 557:20-25. [PMID: 33857841 DOI: 10.1016/j.bbrc.2021.03.124] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 03/22/2021] [Indexed: 11/18/2022]
Abstract
Protoporphyrinogen IX oxidase (PPO) is the last common enzyme in chlorophyll and heme biosynthesis pathways. In human, point mutations on PPO are responsible for the dominantly inherited disorder disease, Variegate Porphyria (VP). Of the VP-causing mutation site, the Arg59 is by far the most prevalent VP mutation residue identified. Multiple sequences alignment of PPOs shows that the Arg59 of human PPO (hPPO) is not conserved, and experiments have shown that the equivalent residues in PPO from various species are essential for enzymatic activity. In this work, it was proposed that the Arg59 performs its function by forming a hydrogen-bonding (HB) network around it in hPPO, and we investigated the role of the HB network via site-directed mutagenesis, enzymatic kinetics and computational studies. We found the integrity of the HB network around Arg59 is important for enzyme activity. The HB network maintains the substrate binding chamber by holding the side chain of Arg59, while it stabilizes the micro-environment of the isoalloxazine ring of FAD, which is favorable for the substrate-FAD interaction. Our result provides a new insight to understanding the relationship between the structure and function for hPPO that non-conserved residues can form a conserved element to maintain the function of protein.
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Affiliation(s)
- Baifan Wang
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin, 300071, China
| | - Zijuan Zhang
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin, 300071, China
| | - Hao Zhu
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin, 300071, China
| | - Congwei Niu
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin, 300071, China
| | - Xin Wen
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin, 300071, China.
| | - Zhen Xi
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin, 300071, China.
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Lee WH, Kwon YB, Lee KH, Choi J, Seu Y. Synthesis of Cyclopropyl Ester and Amide Substituted Pyrimidinediones as Protoporphyrinogen Oxidase‐Inhibiting Herbicides. B KOREAN CHEM SOC 2021. [DOI: 10.1002/bkcs.12205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Won Hyung Lee
- Central Research Institute, Kyung Nong Co. Ltd. Gyeongju 38175 Gyeongsangbuk‐do Republic of Korea
- School of Life Sciences and Biotechnology Kyungpook National University Daegu 41566 Republic of Korea
| | - Young Bin Kwon
- Central Research Institute, Kyung Nong Co. Ltd. Gyeongju 38175 Gyeongsangbuk‐do Republic of Korea
| | - Kye Hwan Lee
- Central Research Institute, Kyung Nong Co. Ltd. Gyeongju 38175 Gyeongsangbuk‐do Republic of Korea
| | - Jong‐Soo Choi
- School of Life Sciences and Biotechnology Kyungpook National University Daegu 41566 Republic of Korea
| | - Young‐Bae Seu
- School of Life Sciences and Biotechnology Kyungpook National University Daegu 41566 Republic of Korea
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Baumbach P, Schmidt-Winter C, Hoefer J, Derlien S, Best N, Herbsleb M, Coldewey SM. A Pilot Study on the Association of Mitochondrial Oxygen Metabolism and Gas Exchange During Cardiopulmonary Exercise Testing: Is There a Mitochondrial Threshold? Front Med (Lausanne) 2020; 7:585462. [PMID: 33409287 PMCID: PMC7779397 DOI: 10.3389/fmed.2020.585462] [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: 07/20/2020] [Accepted: 10/15/2020] [Indexed: 12/28/2022] Open
Abstract
Background: Mitochondria are the key players in aerobic energy generation via oxidative phosphorylation. Consequently, mitochondrial function has implications on physical performance in health and disease ranging from high performance sports to critical illness. The protoporphyrin IX-triplet state lifetime technique (PpIX-TSLT) allows in vivo measurements of mitochondrial oxygen tension (mitoPO2). Hitherto, few data exist on the relation of mitochondrial oxygen metabolism and ergospirometry-derived variables during physical performance. This study investigates the association of mitochondrial oxygen metabolism with gas exchange and blood gas analysis variables assessed during cardiopulmonary exercise testing (CPET) in aerobic and anaerobic metabolic phases. Methods: Seventeen volunteers underwent an exhaustive CPET (graded multistage protocol, 50 W/5 min increase), of which 14 were included in the analysis. At baseline and for every load level PpIX-TSLT-derived mitoPO2 measurements were performed every 10 s with 1 intermediate dynamic measurement to obtain mitochondrial oxygen consumption and delivery (mito V . O2, mito D . O2). In addition, variables of gas exchange and capillary blood gas analyses were obtained to determine ventilatory and lactate thresholds (VT, LT). Metabolic phases were defined in relation to VT1 and VT2 (aerobic: <VT1, aerobic-anaerobic transition: ≥VT1 and <VT2 and anaerobic: ≥VT2). We used linear mixed models to compare variables of PpIX-TSLT between metabolic phases and to analyze their associations with variables of gas exchange and capillary blood gas analyses. Results: MitoPO2 increased from the aerobic to the aerobic-anaerobic phase followed by a subsequent decline. A mitoPO2 peak, termed mitochondrial threshold (MT), was observed in most subjects close to LT2. Mito D . O2 increased during CPET, while no changes in mito V . O2 were observed. MitoPO2 was negatively associated with partial pressure of end-tidal oxygen and capillary partial pressure of oxygen and positively associated with partial pressure of end-tidal carbon dioxide and capillary partial pressure of carbon dioxide. Mito D . O2 was associated with cardiovascular variables. We found no consistent association for mito V . O2. Conclusion: Our results indicate an association between pulmonary respiration and cutaneous mitoPO2 during physical exercise. The observed mitochondrial threshold, coinciding with the metabolic transition from an aerobic to an anaerobic state, might be of importance in critical care as well as in sports medicine.
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Affiliation(s)
- Philipp Baumbach
- Department of Anesthesiology and Intensive Care Medicine, Jena University Hospital, Jena, Germany.,Septomics Research Center, Jena University Hospital, Jena, Germany
| | - Christiane Schmidt-Winter
- Department of Anesthesiology and Intensive Care Medicine, Jena University Hospital, Jena, Germany.,Septomics Research Center, Jena University Hospital, Jena, Germany
| | - Jan Hoefer
- Department of Anesthesiology and Intensive Care Medicine, Jena University Hospital, Jena, Germany.,Septomics Research Center, Jena University Hospital, Jena, Germany
| | - Steffen Derlien
- Institute of Physiotherapy, Jena University Hospital, Jena, Germany
| | - Norman Best
- Institute of Physiotherapy, Jena University Hospital, Jena, Germany
| | - Marco Herbsleb
- Department of Sports Medicine and Health Promotion, Friedrich Schiller University, Jena, Germany
| | - Sina M Coldewey
- Department of Anesthesiology and Intensive Care Medicine, Jena University Hospital, Jena, Germany.,Septomics Research Center, Jena University Hospital, Jena, Germany.,Center for Sepsis Control and Care, Jena University Hospital, Jena, Germany
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Abstract
PURPOSE OF REVIEW To fully exploit the concept of hemodynamic coherence in resuscitating critically ill one should preferably take into account information about the state of parenchymal cells. Monitoring of mitochondrial oxygen tension (mitoPO2) has emerged as a clinical means to assess information of oxygen delivery and oxygen utilization at the mitochondrial level. This review will outline the basics of the technique, summarize its development and describe the rationale of measuring oxygen at the mitochondrial level. RECENT FINDINGS Mitochondrial oxygen tension can be measured by means of the protoporphyrin IX-Triplet State Lifetime Technique (PpIX-TSLT). After validation and use in preclinical animal models, the technique has recently become commercially available in the form of a clinical measuring system. This system has now been used in a number of healthy volunteer studies and is currently being evaluated in studies in perioperative and intensive care patients in several European university hospitals. SUMMARY PpIX-TSLT is a noninvasive and well tolerated method to assess aspects of mitochondrial function at the bedside. It allows doctors to look beyond the macrocirculation and microcirculation and to take the oxygen balance at the cellular level into account in treatment strategies.
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Zeb A, Park C, Son M, Baek A, Cho Y, Kim D, Rampogu S, Lee G, Kwak YS, Park SJ, Lee KW. Integration of virtual screening and computational simulation identifies photodynamic therapeutics against human Protoporphyrinogen Oxidase IX (hPPO). ARAB J CHEM 2020. [DOI: 10.1016/j.arabjc.2018.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
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Nie H, Mansfield BC, Harre NT, Young JM, Steppig NR, Young BG. Investigating target-site resistance mechanism to the PPO-inhibiting herbicide fomesafen in waterhemp and interspecific hybridization of Amaranthus species using next generation sequencing. PEST MANAGEMENT SCIENCE 2019; 75:3235-3244. [PMID: 30983048 DOI: 10.1002/ps.5445] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Revised: 04/07/2019] [Accepted: 04/14/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND Waterhemp (Amaranthus tuberculatus (Moq.) J. D. Sauer) is one of the most pernicious weeds in cropping systems of the USA due to its evolved resistance against several herbicide sites-of-action, including protoporphyrinogen oxidase inhibitors (PPO-R). Currently, the only source of PPO-R documented in waterhemp is ΔG210 of PPX2. Gene flow may not only lead to a transfer of herbicide-resistant alleles, but also produce a hybrid genotype more competitively fit than one or both parents. However, investigating gene flow of Amaranthus species has been of interest in the past two decades with limited evidence. RESULTS Here, a high-throughput MiSeq amplicon sequencing method was used to investigate alterations of the PPX2 gene in 146 PPO-R waterhemp populations across five Midwest states of the USA. Five R128 codons of PPX2, novel to waterhemp, were found including AGG (R), GGA (G), GGG (G), AAA (K) and ATA (I). R128G, R128I, and R128K were found in 11, 3, and 2 populations, respectively. R128G and R128I, but not R128K, conferred fomesafen resistance in a bacterial system. Sequence alignment of the R128 region of PPX2 identified a tumble pigweed (Amaranthus albus)-type and Palmer amaranth (Amaranthus palmeri)-type PPX2 allele to be present and widespread in the surveyed waterhemp populations, thus providing strong evidence of gene flow between Amaranthus species. CONCLUSION Using a next-generation sequencing method, we identified two PPO target-site mutations R128G/I novel to waterhemp and provided evidence of gene flow of Amaranthus species in a large group of screened waterhemp populations from five Midwest states of the USA. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Haozhen Nie
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
| | - Brent C Mansfield
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
| | - Nick T Harre
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
| | - Julie M Young
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
| | - Nicholas R Steppig
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
| | - Bryan G Young
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
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Gao W, Li X, Ren D, Sun S, Huo J, Wang Y, Chen L, Zhang J. Design and Synthesis of N-phenyl Phthalimides as Potent Protoporphyrinogen Oxidase Inhibitors. Molecules 2019; 24:molecules24234363. [PMID: 31795340 PMCID: PMC6930678 DOI: 10.3390/molecules24234363] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 11/26/2019] [Accepted: 11/27/2019] [Indexed: 11/16/2022] Open
Abstract
Protoporphyrinogen oxidase (PPO) has been identified as one of the most promising targets for herbicide discovery. A series of novel phthalimide derivatives were designed by molecular docking studies targeting the crystal structure of mitochondrial PPO from tobacco (mtPPO, PDB: 1SEZ) by using Flumioxazin as a lead, after which the derivatives were synthesized and characterized, and their herbicidal activities were subsequently evaluated. The herbicidal bioassay results showed that compounds such as 3a (2-(4-bromo-2,6-difluorophenyl) isoindoline-1,3-dione), 3d (methyl 2-(4-chloro-1,3-dioxoisoindolin-2-yl)-5-fluorobenzoate), 3g (4-chloro-2-(5-methylisoxazol-3-yl) isoindoline-1,3-dione), 3j (4-chloro-2-(thiophen-2-ylmethyl) isoindoline-1,3-dione) and 3r (2-(4-bromo-2,6-difluorophenyl)-4-fluoroisoindoline-1,3-dione) had good herbicidal activities; among them, 3a showed excellent herbicidal efficacy against A. retroflexus and B. campestris via the small cup method and via pre-emergence and post-emergence spray treatments. The efficacy was comparable to that of the commercial herbicides Flumioxazin, Atrazine, and Chlortoluron. Further, the enzyme activity assay results suggest that the mode of action of compound 3a involves the inhibition of the PPO enzyme, and 3a showed better inhibitory activity against PPO than did Flumioxazin. These results indicate that our molecular design strategy contributes to the development of novel promising PPO inhibitors.
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Akter M, Shiraishi A, Kumura H, Hayakawa T, Wakamatsu JI. Investigation of contributors to zinc protoporphyrin IX formation at optimum pH 5.5 in pork. Anim Sci J 2019; 90:774-780. [PMID: 30997727 DOI: 10.1111/asj.13201] [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: 11/29/2018] [Revised: 01/25/2019] [Accepted: 02/18/2019] [Indexed: 11/29/2022]
Abstract
We investigated zinc protoporphyrin (ZnPP) formation in pork at pH 5.5, identified the contributors to ZnPP formation, and verified the involvement of myoglobin in this process. When pork homogenate was separated into two water-soluble fractions (>10 and <10 kDa) and an insoluble fraction, ZnPP formation was suppressed. ZnPP formation was rescued after mixing of all three fractions. Heating of the soluble <10 kDa fraction did not suppress the formation of ZnPP as opposed to heating of the soluble >10 kDa fraction, suggesting that protein(s) presents in the >10 kDa fraction contributed to ZnPP formation. Components of the soluble 10-30 kDa fractions separated by ultrafiltration were important in ZnPP formation. Exogenous myoglobin was not essential for ZnPP formation. A gel filtration study showed that soluble protein(s) with molecular weight higher than that of myoglobin was involved. Therefore, it was suggested that the soluble <10 kDa fraction, the insoluble fraction, and the soluble 10-30 kDa fraction (excluding myoglobin) are essential for ZnPP formation in pork at pH 5.5.
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Affiliation(s)
- Mofassara Akter
- Laboratory of Applied Food Science, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan
| | - Akiko Shiraishi
- Laboratory of Applied Food Science, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan
| | - Haruto Kumura
- Laboratory of Applied Food Science, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan
| | - Toru Hayakawa
- Laboratory of Applied Food Science, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan
| | - Jun-Ichi Wakamatsu
- Laboratory of Applied Food Science, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan
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Synthesis of 1,3,4-thiadiazol-2(3H)-one derivatives via an unexpected intramolecular addition-elimination reaction of 1,3,4-thiadiazoles. Tetrahedron 2017. [DOI: 10.1016/j.tet.2017.06.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Wang B, Wen X, Xi Z. Molecular Simulations Bring New Insights into Protoporphyrinogen IX Oxidase/Protoporphyrinogen IX Interaction Modes. Mol Inform 2016; 35:476-482. [DOI: 10.1002/minf.201600008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 06/27/2016] [Indexed: 02/05/2023]
Affiliation(s)
- Baifan Wang
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, Nankai University; Collaborative Innovation Center of Chemical Science and Engineering; Tianjin 300071 P. R. China
| | - Xin Wen
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, Nankai University; Collaborative Innovation Center of Chemical Science and Engineering; Tianjin 300071 P. R. China
| | - Zhen Xi
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, Nankai University; Collaborative Innovation Center of Chemical Science and Engineering; Tianjin 300071 P. R. China
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Wu H, Zeng F, Zhang H, Xu J, Qiu J, Wu S. A Nanosystem Capable of Releasing a Photosensitizer Bioprecursor under Two-Photon Irradiation for Photodynamic Therapy. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2016; 3:1500254. [PMID: 27774388 PMCID: PMC5063179 DOI: 10.1002/advs.201500254] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 09/11/2015] [Indexed: 05/03/2023]
Abstract
The applications of photodynamic therapy (PDT) are usually limited by photosensitizers' side effects and singlet oxygen's short half-life. Herein, a mitochondria-targeted nanosystem is demonstrated to enhance the PDT efficacy by releasing a bio-precursor of photosensitizer under two-photon irradiation. A phototriggerable coumarin derivative is first synthesized by linking 5-aminolevulinic acid (5-ALA, the bio-precursor) to coumarin; and the nanosystem (CD-ALA-TPP) is then fabricated by covalently incorporating this coumarin derivative and a mitochondria-targeting compound triphenylphosphonium (TPP) onto carbon dots (CDs). Upon cellular internalization, the nanosystem preferentially accumulates in mitochondria; and under one- or two-photon irradiation, it releases 5-ALA molecules that are then metabolized into protoporphyrin IX in mitochondria through a series of biosynthesis processes. The subsequent red light irradiation induces this endogenously synthesized photosensitizer to generate singlet oxygen, thereby causing oxidant damage to mitochondria and then the apoptosis of the cells. Analysis via 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assays indicate that the novel PDT system exhibits enhanced cytotoxicity toward cancer cells. This study may offer a new strategy for designing PDT systems with high efficacy and low side effects.
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Affiliation(s)
- Hao Wu
- College of Materials Science and Engineering State Key Laboratory of Luminescent Materials and Devices South China University of Technology Guangzhou 510640 P.R. China
| | - Fang Zeng
- College of Materials Science and Engineering State Key Laboratory of Luminescent Materials and Devices South China University of Technology Guangzhou 510640 P.R. China
| | - Hang Zhang
- Institute of Optical Communication Materials State Key Laboratory of Luminescent Materials and Devices South China University of Technology Guangzhou 510640 P.R. China
| | - Jiangsheng Xu
- College of Materials Science and Engineering State Key Laboratory of Luminescent Materials and Devices South China University of Technology Guangzhou 510640 P.R. China
| | - Jianrong Qiu
- Institute of Optical Communication Materials State Key Laboratory of Luminescent Materials and Devices South China University of Technology Guangzhou 510640 P.R. China
| | - Shuizhu Wu
- College of Materials Science and Engineering State Key Laboratory of Luminescent Materials and Devices South China University of Technology Guangzhou 510640 P.R. China
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Zuo Y, Wu Q, Su SW, Niu CW, Xi Z, Yang GF. Synthesis, Herbicidal Activity, and QSAR of Novel N-Benzothiazolyl- pyrimidine-2,4-diones as Protoporphyrinogen Oxidase Inhibitors. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2016; 64:552-62. [PMID: 26728549 DOI: 10.1021/acs.jafc.5b05378] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Protoporphyrinogen oxidase (PPO, E.C. 1.3.3.4) is known as a key action target for several structurally diverse herbicides. As a continuation of our research work on the development of new PPO-inhibiting herbicides, a series of novel 3-(2'-halo-5'-substituted-benzothiazol-1'-yl)-1-methyl-6-(trifluoromethyl)pyrimidine-2,4-diones 9 were designed and synthesized. The bioassay results indicated that a number of the newly synthesized compounds exhibited higher inhibition activity against tobacco PPO (mtPPO) than the controls, saflufenacil and sulfentrazone. Compound 9F-5 was identified as the most potent inhibitor with a Ki value of 0.0072 μM against mtPPO, showing about 4.2-fold and 1.4-fold higher potency than sulfentrazone (Ki = 0.03 μM) and saflufenacil (Ki = 0.01 μM), respectively. An additional green house assay demonstrated that compound 9F-6 (Ki = 0.012 μM) displayed the most promising postemergence herbicidal activity with a broad spectrum even at a concentration as low as 37.5 g of active ingredient (ai)/ha. Maize exhibits relative tolerance against compound 9F-6 at the dosage of 150 g ai/ha, but it is susceptible to saflufenacil even at 75 g ai/ha. Thus, compound 9F-6 exhibits the potential to be a new herbicide for weed control in maize fields.
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Affiliation(s)
- Yang Zuo
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University , Wuhan 430079, P. R. China
| | - Qiongyou Wu
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University , Wuhan 430079, P. R. China
| | - Sun-Wen Su
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University , Wuhan 430079, P. R. China
| | - Cong-Wei Niu
- State Key Laboratory of Elemento-Organic Chemistry, Nankai University , Tianjin 300071, P. R. China
| | - Zhen Xi
- State Key Laboratory of Elemento-Organic Chemistry, Nankai University , Tianjin 300071, P. R. China
| | - Guang-Fu Yang
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University , Wuhan 430079, P. R. China
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16
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Ince C, Mik EG. Microcirculatory and mitochondrial hypoxia in sepsis, shock, and resuscitation. J Appl Physiol (1985) 2016; 120:226-35. [DOI: 10.1152/japplphysiol.00298.2015] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 06/05/2015] [Indexed: 12/23/2022] Open
Abstract
After shock, persistent oxygen extraction deficit despite the apparent adequate recovery of systemic hemodynamic and oxygen-derived variables has been a source of uncertainty and controversy. Dysfunction of oxygen transport pathways during intensive care underlies the sequelae that lead to organ failure, and the limitations of techniques used to measure tissue oxygenation in vivo have contributed to the lack of progress in this area. Novel techniques have provided detailed quantitative insight into the determinants of microcirculatory and mitochondrial oxygenation. These techniques, which are based on the oxygen-dependent quenching of phosphorescence or delayed luminescence are briefly reviewed. The application of these techniques to animal models of shock and resuscitation revealed the heterogeneous nature of oxygen distributions and the alterations in oxygen distribution in the microcirculation and in mitochondria. These studies identified functional shunting in the microcirculation as an underlying cause of oxygen extraction deficit observed in states of shock and resuscitation. The translation of these concepts to the bedside has been enabled by our development and clinical introduction of hand-held microscopy. This tool facilitates the direct observation of the microcirculation and its alterations at the bedside under the conditions of shock and resuscitation. Studies identified loss of coherence between the macrocirculation and the microcirculation, in which resuscitation successfully restored systemic circulation but did not alleviate microcirculatory perfusion alterations. Various mechanisms responsible for these alterations underlie the loss of hemodynamic coherence during unsuccessful resuscitation procedures. Therapeutic resolution of persistent heterogeneous microcirculatory alterations is expected to improve outcomes in critically ill patients.
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Affiliation(s)
- Can Ince
- Department of Intensive Care, Erasmus MC, University Medical Center, Rotterdam
- Department of Translational Physiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Egbert G. Mik
- Department of Intensive Care, Erasmus MC, University Medical Center, Rotterdam
- Department of Anesthesiology, Erasmus MC, University Medical Center, Rotterdam; and
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17
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Balestra GM, Aalders MCG, Specht PAC, Ince C, Mik EG. Oxygenation measurement by multi-wavelength oxygen-dependent phosphorescence and delayed fluorescence: catchment depth and application in intact heart. JOURNAL OF BIOPHOTONICS 2015; 8:615-628. [PMID: 25250821 DOI: 10.1002/jbio.201400054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 07/11/2014] [Accepted: 08/18/2014] [Indexed: 06/03/2023]
Abstract
Oxygen delivery and metabolism represent key factors for organ function in health and disease. We describe the optical key characteristics of a technique to comprehensively measure oxygen tension (PO(2)) in myocardium, using oxygen-dependent quenching of phosphorescence and delayed fluorescence of porphyrins, by means of Monte Carlo simulations and ex vivo experiments. Oxyphor G2 (microvascular PO(2)) was excited at 442 nm and 632 nm and protoporphyrin IX (mitochondrial PO(2)) at 510 nm. This resulted in catchment depths of 161 (86) µm, 350 (307) µm and 262 (255) µm respectively, as estimated by Monte Carlo simulations and ex vivo experiments (brackets). The feasibility to detect changes in oxygenation within separate anatomical compartments is demonstrated in rat heart in vivo. Schematic of ex vivo measurements.
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Affiliation(s)
- Gianmarco M Balestra
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus MC - University Medical Center Rotterdam, Rotterdam, The Netherlands
- Department of Medical Intensive Care, University Hospital Basel, Switzerland
- Department of Translational Physiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Maurice C G Aalders
- Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, The Netherlands
| | - Patricia A C Specht
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus MC - University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Can Ince
- Department of Translational Physiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Egbert G Mik
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus MC - University Medical Center Rotterdam, Rotterdam, The Netherlands
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18
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Mechanistic insights into the substrate recognition of PPO: toward the rational design of effective inhibitors. Future Med Chem 2015; 6:597-9. [PMID: 24895889 DOI: 10.4155/fmc.14.29] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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19
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Hao GF, Tan Y, Xu WF, Cao RJ, Xi Z, Yang GF. Understanding resistance mechanism of protoporphyrinogen oxidase-inhibiting herbicides: insights from computational mutation scanning and site-directed mutagenesis. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:7209-15. [PMID: 24983412 DOI: 10.1021/jf5018115] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The potential of protoporphyrinogen oxidase (PPO) to develop resistance against five PPO-inhibiting herbicides has been studied using computational mutation scanning (CMS) protocol, leading to valuable insights into the resistance mechanisms and structure-resistance relationship of the PPO inhibitors. The calculated shifts in the binding free energies caused by the mutations correlated very well with those derived from the corresponding experimental data obtained from site-directed mutagenesis of PPO, leading to valuable insights into the resistance mechanisms of PPO inhibitors. The calculated entropy change was related to the conformational flexibility of the inhibitor, which demonstrated that inhibitors with appropriate conformational flexibility may inhibit both the wild type and mutants simultaneously. The reasonable correlation between the computational and experimental data further validate that CMS protocol is valuable for predicting resistance associated with amino acid mutations on target proteins.
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Affiliation(s)
- Ge-Fei Hao
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University , Wuhan, P. R. China
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Hao GF, Tan Y, Yang SG, Wang ZF, Zhan CG, Xi Z, Yang GF. Computational and experimental insights into the mechanism of substrate recognition and feedback inhibition of protoporphyrinogen oxidase. PLoS One 2013; 8:e69198. [PMID: 23935953 PMCID: PMC3720618 DOI: 10.1371/journal.pone.0069198] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 06/05/2013] [Indexed: 11/20/2022] Open
Abstract
Protoporphyrinogen IX oxidase (PPO; EC 1.3.3.4) is an essential enzyme catalyzing the last common step in the pathway leading to heme and chlorophyll biosynthesis. Great interest in PPO inhibitors arises from both its significance to agriculture and medicine. However, the discovery of PPO inhibitors with ultrahigh potency and selectivity is hampered due to lack of structural and mechanistic understanding about the substrate recognition, which remains a longstanding question central in porphyrin biology. To understand the mechanism, a novel binding model of protogen (protoporphyrinogen IX, the substrate) was developed through extensive computational simulations. Subsequently, amino acid residues that are critical for protogen binding identified by computational simulations were substituted by mutagenesis. Kinetic analyses of these mutants indicated that these residues were critical for protogen binding. In addition, the calculated free energies of protogen binding with these mutants correlated well with the experimental data, indicating the reasonability of the binding model. On the basis of this novel model, the fundamental mechanism of substrate recognition was investigated by performing potential of mean force (PMF) calculations, which provided an atomic level description of conformational changes and pathway intermediates. The free energy profile revealed a feedback inhibition mechanism of proto (protoporphyrin IX, the product), which was also in agreement with experimental evidence. The novel mechanistic insights obtained from this study present a new starting point for future rational design of more efficient PPO inhibitors based on the product-bound PPO structure.
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Affiliation(s)
- Ge-Fei Hao
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, P. R. China
| | - Ying Tan
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, P. R. China
- State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, P. R. China
| | - Sheng-Gang Yang
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, P. R. China
| | - Zhi-Fang Wang
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, P. R. China
- State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, P. R. China
| | - Chang-Guo Zhan
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky, United States of America
| | - Zhen Xi
- State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, P. R. China
| | - Guang-Fu Yang
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, P. R. China
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Zuo Y, Yang SG, Luo YP, Tan Y, Hao GF, Wu QY, Xi Z, Yang GF. Design and synthesis of 1-(benzothiazol-5-yl)-1H-1,2,4-triazol-5-ones as protoporphyrinogen oxidase inhibitors. Bioorg Med Chem 2013; 21:3245-55. [PMID: 23623257 DOI: 10.1016/j.bmc.2013.03.056] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 03/07/2013] [Accepted: 03/09/2013] [Indexed: 11/17/2022]
Abstract
Protoporphyrinogen oxidase (PPO, E.C. 1.3.3.4) is the action target for several structurally diverse herbicides. A series of novel 4-(difluoromethyl)-1-(6-halo-2-substituted-benzothiazol-5-yl)-3-methyl-1H-1,2,4-triazol-5(4H)-ones 2a-z were designed and synthesized via the ring-closure of two ortho-substituents. The in vitro bioassay results indicated that the 26 newly synthesized compounds exhibited good PPO inhibition effects with K(i) values ranging from 0.06 to 17.79 μM. Compound 2e, ethyl 2-{[5-(4-(difluoromethyl)-3-methyl-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl)-6-fluorobenzo-thiazol-2-yl]thio}acetate, was the most potent inhibitor with K(i) value of 0.06 μM against mtPPO, comparable to (K(i)=0.03 μM) sulfentrazone. Further green house assays showed that compound 2f (K(i)=0.24 μM, mtPPO), ethyl 2-{[5-(4-(difluoromethyl)-3-methyl-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl)-6-fluorobenzothiazol-2-yl]thio}propanoate, showed the most promising post-emergence herbicidal activity with broad spectrum even at concentrations as low as 37.5 gai/ha. Soybean exhibited tolerance to compound 2f at the dosages of 150 gai/ha, whereas they are susceptible to sulfentrazone even at 75 gai/ha. Thus, compound 2f might be a potential candidate as a new herbicide for soybean fields.
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Affiliation(s)
- Yang Zuo
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, PR China
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23
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Bodmer SIA, Balestra GM, Harms FA, Johannes T, Raat NJH, Stolker RJ, Mik EG. Microvascular and mitochondrial PO(2) simultaneously measured by oxygen-dependent delayed luminescence. JOURNAL OF BIOPHOTONICS 2012; 5:140-151. [PMID: 22114031 DOI: 10.1002/jbio.201100082] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 11/03/2011] [Accepted: 11/03/2011] [Indexed: 05/31/2023]
Abstract
Measurement of tissue oxygenation is a complex task and various techniques have led to a wide range of tissue PO(2) values and contradictory results. Tissue is compartmentalized in microcirculation, interstitium and intracellular space and current techniques are biased towards a certain compartment. Simultaneous oxygen measurements in various compartments might be of great benefit for our understanding of determinants of tissue oxygenation. Here we report simultaneous measurement of microvascular PO(2) (μPO(2) ) and mitochondrial PO(2) (mitoPO(2) ) in rats. The μPO(2) measurements are based on oxygen-dependent quenching of phosphorescence of the near-infrared phosphor Oxyphor G2. The mitoPO(2) measurements are based on oxygen-dependent quenching of delayed fluorescence of protoporphyrin IX (PpIX). Favorable spectral properties of these porphyrins allow simultaneous measurement of the delayed luminescence lifetimes. A dedicated fiber-based time-domain setup consisting of a tunable pulsed laser, 2 red-sensitive gated photomultiplier tubes and a simultaneous sampling data-acquisition system is described in detail. The absence of cross talk between the channels is shown and the feasibility of simultaneous μPO(2) and mitoPO(2) measurements is demonstrated in rat liver in vivo. It is anticipated that this novel approach will greatly contribute to our understanding of tissue oxygenation in physiological and pathological circumstances.
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Affiliation(s)
- Sander I A Bodmer
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus MC - University Medical Center Rotterdam, s-Gravendijkwal 230, 3015 CE, Rotterdam, The Netherlands
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24
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Zuo Y, Yang SG, Jiang LL, Hao GF, Wang ZF, Wu QY, Xi Z, Yang GF. Quantitative structure–activity relationships of 1,3,4-thiadiazol-2(3H)-ones and 1,3,4-oxadiazol-2(3H)-ones as human protoporphyrinogen oxidase inhibitors. Bioorg Med Chem 2012; 20:296-304. [DOI: 10.1016/j.bmc.2011.10.079] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 10/29/2011] [Accepted: 10/29/2011] [Indexed: 10/15/2022]
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25
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Hao GF, Tan Y, Yu NX, Yang GF. Structure–activity relationships of diphenyl-ether as protoporphyrinogen oxidase inhibitors: insights from computational simulations. J Comput Aided Mol Des 2011; 25:213-22. [DOI: 10.1007/s10822-011-9412-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2010] [Accepted: 01/10/2011] [Indexed: 11/28/2022]
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26
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Qin X, Sun L, Wen X, Yang X, Tan Y, Jin H, Cao Q, Zhou W, Xi Z, Shen Y. Structural insight into unique properties of protoporphyrinogen oxidase from Bacillus subtilis. J Struct Biol 2010; 170:76-82. [DOI: 10.1016/j.jsb.2009.11.012] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 11/16/2009] [Accepted: 11/19/2009] [Indexed: 10/20/2022]
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27
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Bioactive conformation analysis of cyclic imides as protoporphyrinogen oxidase inhibitor by combining DFT calculations, QSAR and molecular dynamic simulations. Bioorg Med Chem 2009; 17:4935-42. [DOI: 10.1016/j.bmc.2009.06.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Revised: 05/31/2009] [Accepted: 06/02/2009] [Indexed: 11/20/2022]
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28
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Hao GF, Zhu XL, Ji FQ, Zhang L, Yang GF, Zhan CG. Understanding the mechanism of drug resistance due to a codon deletion in protoporphyrinogen oxidase through computational modeling. J Phys Chem B 2009; 113:4865-75. [PMID: 19284797 DOI: 10.1021/jp807442n] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Protoporphyrinogen oxidase (PPO; EC 1.3.3.4) is the last common enzyme for the enzymatic transformation of protoporphyrinogen-IX to protoporphyrin-IX, which is the key common intermediate leading to heme and chlorophyll. Hence, PPO has been identified as one of the most importance action targets for the treatment of some important diseases including cancer and variegated porphyria (VP). In the agricultural field, PPO inhibitors have been used as herbicides for many years. Recently, a unique drug resistance was found to be associated with a nonactive site residue (Gly210) deletion rather than substitution in A. tuberculatus PPO. In the present study, extensive computational simulations, including homology modeling, molecular dynamics (MD) simulations, and molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) calculations, have been carried out to uncover the detailed molecular mechanism of drug resistance associated with Gly210 deletion. Although Gly210 in the wild-type A. tuberculatus PPO has no direct interaction with the inhibitors, all the computational models and energetic results indicated that Gly210 deletion has great effects on the hydrogen-bonding network and the conformational change of the binding pocket. An interchain hydrogen bond between Gly210 with Ser424, playing an important role in stabilizing the local conformation of the wild-type enzyme, disappeared after Gly210 deletion. As a result, the mutant-type PPO has a lower affinity than the wild-type enzyme, which accounts for the molecular mechanism of drug resistance. The structural and mechanistic insights obtained from the present study provide a new starting point for future rational design of novel PPO inhibitors to overcome drug resistance associated with Gly210 deletion.
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Affiliation(s)
- Ge-Fei Hao
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, PR China
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29
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In vivo mitochondrial oxygen tension measured by a delayed fluorescence lifetime technique. Biophys J 2008; 95:3977-90. [PMID: 18641065 DOI: 10.1529/biophysj.107.126094] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Mitochondrial oxygen tension (mitoPO(2)) is a key parameter for cellular function, which is considered to be affected under various pathophysiological circumstances. Although many techniques for assessing in vivo oxygenation are available, no technique for measuring mitoPO(2) in vivo exists. Here we report in vivo measurement of mitoPO(2) and the recovery of mitoPO(2) histograms in rat liver by a novel optical technique under normal and pathological circumstances. The technique is based on oxygen-dependent quenching of the delayed fluorescence lifetime of protoporphyrin IX. Application of 5-aminolevulinic acid enhanced mitochondrial protoporphyrin IX levels and induced oxygen-dependent delayed fluorescence in various tissues, without affecting mitochondrial respiration. Using fluorescence microscopy, we demonstrate in isolated hepatocytes that the signal is of mitochondrial origin. The delayed fluorescence lifetime was calibrated in isolated hepatocytes and isolated perfused livers. Ultimately, the technique was applied to measure mitoPO(2) in rat liver in vivo. The results demonstrate mitoPO(2) values of approximately 30-40 mmHg. mitoPO(2) was highly sensitive to small changes in inspired oxygen concentration around atmospheric oxygen level. Ischemia-reperfusion interventions showed altered mitoPO(2) distribution, which flattened overall compared to baseline conditions. The reported technology is scalable from microscopic to macroscopic applications, and its reliance on an endogenous compound greatly enhances its potential field of applications.
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30
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Heinemann IU, Jahn M, Jahn D. The biochemistry of heme biosynthesis. Arch Biochem Biophys 2008; 474:238-51. [PMID: 18314007 DOI: 10.1016/j.abb.2008.02.015] [Citation(s) in RCA: 225] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 02/14/2008] [Accepted: 02/14/2008] [Indexed: 02/03/2023]
Abstract
Heme is an integral part of proteins involved in multiple electron transport chains for energy recovery found in almost all forms of life. Moreover, heme is a cofactor of enzymes including catalases, peroxidases, cytochromes of the P(450) class and part of sensor molecules. Here the step-by-step biosynthesis of heme including involved enzymes, their mechanisms and detrimental health consequences caused by their failure are described. Unusual and challenging biochemistry including tRNA-dependent reactions, radical SAM enzymes and substrate derived cofactors are reported.
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Affiliation(s)
- Ilka U Heinemann
- Institute of Microbiology, Technical University of Braunschweig, Spielmannstr. 7, D-38106 Braunschweig, Germany
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31
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Wakamatsu JI, Okui J, Hayashi N, Nishimura T, Hattori A. Zn protoporphyrin IX is formed not from heme but from protoporphyrin IX. Meat Sci 2007; 77:580-6. [DOI: 10.1016/j.meatsci.2007.05.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2006] [Revised: 05/08/2007] [Accepted: 05/08/2007] [Indexed: 11/25/2022]
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Heinemann I, Diekmann N, Masoumi A, Koch M, Messerschmidt A, Jahn M, Jahn D. Functional definition of the tobacco protoporphyrinogen IX oxidase substrate-binding site. Biochem J 2007; 402:575-80. [PMID: 17134376 PMCID: PMC1863572 DOI: 10.1042/bj20061321] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Revised: 11/22/2006] [Accepted: 11/30/2006] [Indexed: 11/17/2022]
Abstract
PPO (protoporphyrinogen IX oxidase) catalyses the flavin-dependent six-electron oxidation of protogen (protoporphyrinogen IX) to form proto (protoporphyrin IX), a crucial step in haem and chlorophyll biosynthesis. The apparent K(m) value for wild-type tobacco PPO2 (mitochondrial PPO) was 1.17 muM, with a V(max) of 4.27 muM.min(-1).mg(-1) and a catalytic activity k(cat) of 6.0 s(-1). Amino acid residues that appear important for substrate binding in a crystal structure-based model of the substrate docked in the active site were interrogated by site-directed mutagenesis. PPO2 variant F392H did not reveal detectable enzyme activity indicating an important role of Phe(392) in substrate ring A stacking. Mutations of Leu(356), Leu(372) and Arg(98) increased k(cat) values up to 100-fold, indicating that the native residues are not essential for establishing an orientation of the substrate conductive to catalysis. Increased K(m) values of these PPO2 variants from 2- to 100-fold suggest that these residues are involved in, but not essential to, substrate binding via rings B and C. Moreover, one prominent structural constellation of human PPO causing the disease variegate porphyria (N67W/S374D) was successfully transferred into the tobacco PPO2 background. Therefore tobacco PPO2 represents a useful model system for the understanding of the structure-function relationship underlying detrimental human enzyme defects.
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Affiliation(s)
- Ilka U. Heinemann
- *Institute of Microbiology, Technical University Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany
| | - Nina Diekmann
- *Institute of Microbiology, Technical University Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany
| | - Ava Masoumi
- *Institute of Microbiology, Technical University Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany
| | - Michael Koch
- †Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Headington, Oxford OX3 7BN, U.K
| | - Albrecht Messerschmidt
- ‡Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Martina Jahn
- *Institute of Microbiology, Technical University Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany
| | - Dieter Jahn
- *Institute of Microbiology, Technical University Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany
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33
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Granick S, Beale SI. Hemes, chlorophylls, and related compounds: biosynthesis and metabolic regulation. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 46:33-203. [PMID: 345768 DOI: 10.1002/9780470122914.ch2] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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34
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Mik EG, Stap J, Sinaasappel M, Beek JF, Aten JA, van Leeuwen TG, Ince C. Mitochondrial PO2 measured by delayed fluorescence of endogenous protoporphyrin IX. Nat Methods 2006; 3:939-45. [PMID: 17060918 DOI: 10.1038/nmeth940] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Accepted: 08/10/2006] [Indexed: 11/09/2022]
Abstract
Molecular oxygen is the primary oxidant in biological systems. The ultimate destination of oxygen in vivo is the mitochondria where it is used in oxidative phosphorylation. The ability of this process to produce an amount of high-energy phosphates adequate to sustain life highly depends on the available amount of oxygen. Despite a vast array of techniques to measure oxygen, major (patho)physiological questions remain unanswered because of the unavailability of quantitative techniques to measure mitochondrial oxygen in situ. Here we demonstrate that mitochondrial PO(2) can be directly measured in living cells by harnessing the delayed fluorescence of endogenous protoporphyrin IX (PpIX), thereby providing a technique with the potential for a wide variety of applications. We applied this technique to different cell lines (V-79 Chinese hamster lung fibroblasts, HeLa cells and IMR 32-K1 neuroblastoma cells) and present the first direct measurements of the oxygen gradient between the mitochondria and the extracellular volume.
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Affiliation(s)
- Egbert G Mik
- Department of Physiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
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35
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Tietjen KG. Quinone activation of protoporphyrinogen oxidase of barley plastids. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/ps.2780330409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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36
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Jacobs JM, Jacobs NJ. Measurement of protoporphyrinogen oxidase activity. CURRENT PROTOCOLS IN TOXICOLOGY 2001; Chapter 8:Unit 8.5. [PMID: 20954158 DOI: 10.1002/0471140856.tx0805s00] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Protoporphyrinogen oxidase catalyzes the oxidation of protoporphyrinogen to protophyrin. It is a membrane-bound mitochondrial enzyme and it is the target of photobleaching herbicides. The basic assay presented in this unit for measuring oxidase activity is based on oxidation of the colorless, nonfluorescent substrate, protoporphyrinogen, to the colored, fluorescent protophyrin. Alternate protocols are provided for the measuring the accumulation of protoporphyrinogen resulting from a decrease in oxidase activity due to treatment with diphenyl ether herbicides or oxidase inhibitor.
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Affiliation(s)
- J M Jacobs
- Dartmouth Medical School, Hanover, New Hampshire, USA
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Georgakoudi I, Keng PC, Foster TH. Hypoxia significantly reduces aminolaevulinic acid-induced protoporphyrin IX synthesis in EMT6 cells. Br J Cancer 1999; 79:1372-7. [PMID: 10188878 PMCID: PMC2362734 DOI: 10.1038/sj.bjc.6690220] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
We have studied the effects of hypoxia on aminolaevulinic acid (ALA)-induced protoporphyrin IX (PpIX) synthesis in EMT6 monolayer cultures characterized by different cell densities and proliferation rates. Specifically, after ALA incubation under hypoxic or normoxic conditions, we detected spectrofluorometrically the PpIX content of the following populations: (a) low-density exponentially growing cells; (b) high-density fed-plateau cells; and (c) high-density unfed-plateau cells. These populations were selected either for the purpose of comparison with other in vitro studies (low-density exponentially growing cells) or as representatives of tumour regions adjacent to (high-density fed-plateau cells) and further away from (high-density unfed-plateau cells) capillaries. The amount of PpIX per cell produced by each one of these populations was higher after normoxic ALA incubation. The magnitude of the effect of hypoxia on PpIX synthesis was dependent on cell density and proliferation rate. A 42-fold decrease in PpIX fluorescence was observed for the high-density unfed-plateau cells. PpIX production by the low-density exponential cells was affected the least by ALA incubation under hypoxic conditions (1.4-fold decrease), whereas the effect on the high-density fed-plateau population was intermediate (20-fold decrease).
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Affiliation(s)
- I Georgakoudi
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, NY 14642, USA
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Affiliation(s)
- J T Hindmarsh
- Department of Pathology, University of Ottawa Faculty of Medicine, Ontario, Canada
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Abstract
The porphyrias are metabolic disorders characterized by abnormal heme biosynthesis with excessive accumulation and excretion of porphyrias or porphyrin precursors. Defects in the enzymes of the heme biosynthetic pathway result in porphyria. Several of the disorders have been classified as hepatic because the major site of the biochemical defect has been localized to the liver. This article describes the enzymes of the heme biosynthetic pathway, the clinical features of the hepatic porphyrias and management of the disorders.
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Affiliation(s)
- Y V Scarlett
- Division of Digestive Diseases and Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Lermontova I, Kruse E, Mock HP, Grimm B. Cloning and characterization of a plastidal and a mitochondrial isoform of tobacco protoporphyrinogen IX oxidase. Proc Natl Acad Sci U S A 1997; 94:8895-900. [PMID: 9238074 PMCID: PMC23187 DOI: 10.1073/pnas.94.16.8895] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/1997] [Accepted: 05/23/1997] [Indexed: 02/04/2023] Open
Abstract
Protoporphyrinogen IX oxidase is the last enzyme in the common pathway of heme and chlorophyll synthesis and provides precursor for the mitochondrial and plastidic heme synthesis and the predominant chlorophyll synthesis in plastids. We cloned two different, full-length tobacco cDNA sequences by complementation of the protoporphyrin-IX-accumulating Escherichia coli hemG mutant from heme auxotrophy. The two sequences show similarity to the recently published Arabidopsis PPOX, Bacillus subtilis hemY, and to mammalian sequences encoding protoporphyrinogen IX oxidase. One cDNA sequence encodes a 548-amino acid residues protein with a putative transit sequence of 50 amino acid residues, and the second cDNA encodes a protein of 504 amino acid residues. Both deduced protein sequences share 27.2% identical amino acid residues. The first in vitro translated protoporphyrinogen IX oxidase could be translocated to plastids, and the approximately 53-kDa mature protein was detected in stroma and membrane fraction. The second enzyme was targeted to mitochondria without any detectable reduction in size. Localization of both enzymes in subcellular fractions was immunologically confirmed. Steady-state RNA analysis indicates an almost synchronous expression of both genes during tobacco plant development, greening of young seedlings, and diurnal and circadian growth. The mature plastidal and the mitochondrial isoenzyme were overexpressed in E. coli. Bacterial extracts containing the recombinant mitochondrial enzyme exhibit high protoporphyrinogen IX oxidase activity relative to control strains, whereas the plastidal enzyme could only be expressed as an inactive peptide. The data presented confirm a compartmentalized pathway of tetrapyrrole synthesis with protoporphyrinogen IX oxidase in plastids and mitochondria.
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Affiliation(s)
- I Lermontova
- Institut für Pflanzengenetik und Kulturpflanzenforschung Gatersleben, IPK Corrensstrasse 3, 06466 Gatersleben, Germany
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41
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Camadro JM, Labbe P. Cloning and characterization of the yeast HEM14 gene coding for protoporphyrinogen oxidase, the molecular target of diphenyl ether-type herbicides. J Biol Chem 1996; 271:9120-8. [PMID: 8621563 DOI: 10.1074/jbc.271.15.9120] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Protoporphyrinogen oxidase, which catalyzes the oxygen-dependent aromatization of protoporphyrinogen IX to protoporphyrin IX, is the molecular target of diphenyl ether type herbicides. The structural gene for the yeast protoporphyrinogen oxidase, HEM14, was isolated by functional complementation of a hem14-1 protoporphyrinogen oxidase-deficient yeast mutant, using a novel one-step colored screening procedure to identify heme-synthesizing cells. The hem14-1 mutation was genetically linked to URA3, a marker on chromosome V, and HEM14 was physically mapped on the right arm of this chromosome, between PRP22 and FAA2. Disruption of the HEM14 gene leads to protoporphyrinogen oxidase deficiency in vivo (heme deficiency and accumulation of heme precursors), and in vitro (lack of immunodetectable protein or enzyme activity). The HEM14 gene encodes a 539-amino acid protein (59,665 Da; pI 9.3) containing an ADP- beta alpha beta-binding fold similar to those of several other flavoproteins. Yeast protoporphyrinogen oxidase was somewhat similar to the HemY gene product of Bacillus subtilis and to the human and mouse protoporphyrinogen oxidases. Studies on protoporphyrinogen oxidase overexpressed in yeast and purified as wild-type enzyme showed that (i) the NH2-terminal mitochondrial targeting sequence of protoporphyrinogen oxidase is not cleaved during importation; (ii) the enzyme, as purified, had a typical flavin semiquinone absorption spectrum; and (iii) the enzyme was strongly inhibited by diphenyl ether-type herbicides and readily photolabeled by a diazoketone derivative of tritiated acifluorfen. The mutant allele hem14-1 contains two mutations, L422P and K424E, responsible for the inactive enzyme. Both mutations introduced independently in the wild-type HEM14 gene completely inactivated the protein when analyzed in an Escherichia coli expression system.
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Affiliation(s)
- J M Camadro
- Laboratoire de Biochimie des Porphyrines, Département de Microbiologie, Institut Jacques Monod, 2 Place Jussieu, F-75251 Paris Cedex 05, France
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42
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Nishimura K, Taketani S, Inokuchi H. Cloning of a human cDNA for protoporphyrinogen oxidase by complementation in vivo of a hemG mutant of Escherichia coli. J Biol Chem 1995; 270:8076-80. [PMID: 7713909 DOI: 10.1074/jbc.270.14.8076] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Protoporphyrinogen oxidase (PPO; EC 1.3.3.4) is the enzyme that catalyzes in the penultimate step in the heme biosynthetic pathway. Hemes are essential components of redox enzymes, such as cytochromes. Thus, a hemG mutant strain of Escherichia coli deficient in PPO is defective in aerobic respiration and grows poorly even in rich medium. By complementation with a human placental cDNA library, we were able to isolate a clone that enhanced the poor growth of such a hemG mutant strain. The clone encoded the gene for human PPO. Sequence analysis revealed that PPO consists of 477 amino acids with a calculated molecular mass of 50.8 kilodaltons. The deduced protein exhibited a high degree of homology over its entire length to the amino acid sequence of PPO encoded by the hemY gene of Bacillus subtilis. The NH2-terminal amino acid sequence of the deduced PPO contains a conserved amino acid sequence that forms the dinucleotide-binding site in many flavin-containing proteins. Northern blot analysis revealed the synthesis of a 1.8-kilobase pair mRNA for PPO. A homogenate of the monkey kidney COS-1 cells that had been transfected with the cDNA had much higher PPO activity than an extract of control cells, and this activity was inhibited by acifluorfen, a specific inhibitor of PPO. Furthermore, the cDNA was expressed in vitro as 51-kilodalton protein, and after incubation with isolated mitochondria the protein was found to be located in the mitochondria, having just the same size as before, an indication that PPO is a mitochondrial enzyme and has no apparent transport-specific leader sequence.
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Affiliation(s)
- K Nishimura
- Department of Biophysics, Faculty of Science, Kyoto University, Japan
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Camadro JM, Thome F, Brouillet N, Labbe P. Purification and properties of protoporphyrinogen oxidase from the yeast Saccharomyces cerevisiae. Mitochondrial location and evidence for a precursor form of the protein. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)31604-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Abstract
Protoporphyrinogen oxidase (EC 1.3.3.4) (PPO) is the penultimate enzyme of the heme biosynthetic pathway. Mouse PPO has been purified in low yield and kinetically characterized by this laboratory previously. A new more rapid purification procedure is described herein, and with this protein we detect a noncovalently bound flavin moiety. This flavin is present at approximately stoichiometric amounts in the purified enzyme and has been identified by its fluorescence spectrum and high performance liquid chromatography as flavin mononucleotide (FMN). Fluorescence quenching studies on the flavin yielded a Stern-Volmer quenching constant of 12.08 M-1 for iodide and 1.1 M-1 for acrylamide. Quenching of enzyme tryptophan fluorescence resulted in quenching constants of 6 M-1 and 10 M-1 for iodide and acrylamide, respectively. Plasma scans performed on purified enzyme preparations did not reveal the presence of stoichiometric amounts of protein-bound metal ions, and we were unable to detect any protein-associated pyrroloquinoline quinone (PQQ). Data from circular dichroism studies predict a secondary structure of the native protein consisting of 30.5% alpha helix, 40.5% beta sheet, 13.7% turn, and 15.3% random coil. Denaturation of PPO with urea resulted in a biphasic curve when ellipticity is plotted against urea concentration, typical of amphipathic proteins.
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Affiliation(s)
- K L Proulx
- Department of Microbiology, University of Georgia, Athens 30602
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Guo R, Lim CK, Peters TJ. High-performance liquid chromatographic assays for protoporphyrinogen oxidase and ferrochelatase in human leucocytes. JOURNAL OF CHROMATOGRAPHY 1991; 566:383-96. [PMID: 1939451 DOI: 10.1016/0378-4347(91)80255-b] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Rapid, sensitive and specific high-performance liquid chromatographic assays are described for protoporphyrinogen oxidase and ferrochelatase in human leucocytes. The enzyme reaction products were separated and quantitated by reversed-phase high-performance liquid chromatography with fluorescence detection. The optimal pH for the protoporphyrinogen oxidase assay was 8.6 and the Michaelis constant for protoporphyrinogen IX was 9.78 +/- 0.96 microM (mean +/- S.D.). The mean (+/- S.D.) activity of protoporphyrinogen oxidase in fourteen apparently healthy subjects was 0.146 +/- 0.023 nmol protoporphyrin IX per min per mg protein. In one patient with variegate porphyria, the activity was 0.028 nmol protoporphyrin IX per min per mg protein. The optimal pH for ferrochelatase was 7.4 and with protoporphyrin and Zn2+ as substrates, the Michaelis constants were 1.49 and 8.33 microM, respectively. The mean activity of ferrochelatase in ten control subjects was 0.24 nM Zn-protoporphyrin or 2.05 nM Zn-mesoporphyrin formed per h per mg protein.
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Affiliation(s)
- R Guo
- Division of Clinical Cell Biology, MRC Clinical Research Centre, Harrow, Middlesex, UK
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46
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Asson-Batres M, Hare J. Effect of oxygen on the synthesis and assembly of mitochondrial encoded subunits of cytochrome oxidase and cytochrome b.c1 in mouse embryo fibroblasts. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)92908-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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47
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Jacobs JM, Jacobs NJ, Borotz SE, Guerinot ML. Effects of the photobleaching herbicide, acifluorfen-methyl, on protoporphyrinogen oxidation in barley organelles, soybean root mitochondria, soybean root nodules, and bacteria. Arch Biochem Biophys 1990; 280:369-75. [PMID: 2369128 DOI: 10.1016/0003-9861(90)90344-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The photobleaching herbicide, acifluorfen-methyl (AFM), has been reported to be an inhibitor of the heme and chlorophyll biosynthetic enzyme protoporphyrinogen oxidase (Protox) in several plant species. However, AFM had no effect on the levels of Protox activity measured in a mitochondrial fraction from soybean roots. In contrast, AFM inhibited Protox activity in etioplasts from barley leaves and in mitochondria from barley roots, but the extent of inhibition varied depending upon the assay conditions and was maximal only in the presence of 5 mM dithiothreitol (DTT). AFM inhibition was enhanced by preincubation of barley organelle extract in the presence of DTT. Preincubation of barley extract with DTT and AFM together (but not with AFM alone) caused extensive enzyme inhibition which was not reversible by dialysis. These findings have implications for the mechanism of AFM action and for the differential effect of these herbicides on crop and weed species. AFM had no effect on the Protox activity of membranes from free-living bacterial cell of Bradyrhizobium japonicum or Escherichia coli, or on the high levels of Protox activity associated with the plant-derived membrane surrounding the symbiotic bacteria within the soybean root nodule.
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Affiliation(s)
- J M Jacobs
- Department of Microbiology, Dartmouth Medical School, Hanover, New Hampshire
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48
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Ades IZ. Heme production in animal tissues: the regulation of biogenesis of delta-aminolevulinate synthase. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1990; 22:565-78. [PMID: 2199251 DOI: 10.1016/0020-711x(90)90032-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- I Z Ades
- Department of Zoology, University of Maryland, College Park 20742
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49
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Stocker R. Induction of haem oxygenase as a defence against oxidative stress. FREE RADICAL RESEARCH COMMUNICATIONS 1990; 9:101-12. [PMID: 2189794 DOI: 10.3109/10715769009148577] [Citation(s) in RCA: 243] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Cells respond to metabolic perturbations by producing specific stress proteins. Exposure of mammalian cells to various forms of oxidative stress induces haem oxygenase, the rate-limiting enzyme in haem degradation. This response is proposed to represent an antioxidant defence operating at two different stages simultaneously. It (i) decreases the levels of the potential pro-oxidants haem and haem proteins such as cytochrome P-450 and protoporphyrinogen oxidase, and (ii) increases the tissue concentrations of antioxidatively active bile pigments.
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Affiliation(s)
- R Stocker
- Heart Research Institute, Camperdown NSW, Australia
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50
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Jacobs NJ, Borotz SE, Jacobs JM. Characteristics of purified protoporphyrinogen oxidase from barley. Biochem Biophys Res Commun 1989; 161:790-6. [PMID: 2735923 DOI: 10.1016/0006-291x(89)92669-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The membrane bound enzyme oxidizing protoporphyrinogen to protoporphyrin, a step in heme and chlorophyll synthesis, was purified to a single prominent polypeptide band on SDS/PAGE from barley mitochondrial fractions. It contained a variety of lipids including 0.66 mg of phosphatidyl ethanolamine and 0.46 mg of free fatty acid per mg of protein. Iron, but no flavins or cytochromes, was detected. In the presence of glutathione, enzymatic oxidation was inhibited by the iron chelator o-phenanthroline but was stimulated by iron EDTA. The purified enzyme was inhibited by reductants such as glutathione, ascorbate, NADH and NADPH. These findings are compatible with some direct or indirect involvement of lipids and iron in this oxidation in plants.
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Affiliation(s)
- N J Jacobs
- Department of Microbiology, Dartmouth Medical School, Hanover, NH 03756
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