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CENGİZ S, CAVAS L. Can soybean lipoxygenases be real models for mammalian lipoxygenases? A bioinformatics approach. JOURNAL OF THE TURKISH CHEMICAL SOCIETY, SECTION A: CHEMISTRY 2020. [DOI: 10.18596/jotcsa.785109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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2
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Kurakin GF, Samoukina AM, Potapova NA. Bacterial and Protozoan Lipoxygenases Could be Involved in Cell-to-Cell Signaling and Immune Response Suppression. BIOCHEMISTRY (MOSCOW) 2020; 85:1048-1071. [PMID: 33050851 DOI: 10.1134/s0006297920090059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Lipoxygenases are found in animals, plants, and fungi, where they are involved in a wide range of cell-to-cell signaling processes. The presence of lipoxygenases in a number of bacteria and protozoa has been also established, but their biological significance remains poorly understood. Several hypothetical functions of lipoxygenases in bacteria and protozoa have been suggested without experimental validation. The objective of our study was evaluating the functions of bacterial and protozoan lipoxygenases by evolutionary and taxonomic analysis using bioinformatics tools. Lipoxygenase sequences were identified and examined using BLAST, followed by analysis of constructed phylogenetic trees and networks. Our results support the theory on the involvement of lipoxygenases in the formation of multicellular structures by microorganisms and their possible evolutionary significance in the emergence of multicellularity. Furthermore, we observed association of lipoxygenases with the suppression of host immune response by parasitic and symbiotic bacteria including dangerous opportunistic pathogens.
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Affiliation(s)
- G F Kurakin
- Department of Biochemistry and Laboratory Medicine, Tver State Medical University, Ministry of Health of the Russian Federation, Tver, 170100, Russia.
| | - A M Samoukina
- Department of Microbiology, Virology, and Immunology, Tver State Medical University, Ministry of Health of the Russian Federation, Tver, 170100, Russia
| | - N A Potapova
- Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, 127051, Russia.,Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119234, Russia
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Combinatorial strategy towards the efficient expression of lipoxygenase in Escherichia coli at elevated temperatures. Appl Microbiol Biotechnol 2020; 104:10047-10057. [PMID: 33037915 DOI: 10.1007/s00253-020-10941-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 08/31/2020] [Accepted: 10/04/2020] [Indexed: 02/07/2023]
Abstract
Lipoxygenases (LOXs) are a family of non-heme iron oxidoreductases, which catalyze the addition of oxygen into polyunsaturated fatty acids. They have applications in the food and medical industries. In most studies, the soluble expression of LOXs in microbes requires low temperature (< 20 °C), which increases the cost and fermentation time. Achievement of soluble expression in elevated temperatures (> 30 °C) would shorten the production phase, leading to cost-efficient industrial applications. In this study, a combinatorial strategy was used to enhance the expression of soluble LOXs, comprising plasmid stability systems plus optimized carbon source used for auto-induction expression. Plasmid stability analysis suggested that both active partition systems and plasmid-dependent systems were essential for plasmid stability. Among them, the parBCA in it resulted in the enzyme activity increasing by a factor of 2 (498 ± 13 units per gram dry cell weight (U/g-DCW) after 6-h induction). Furthermore, the optimized carbon source, composed of glucose, lactose, and glycerol, could be used as an auto-induction expression medium and effectively improve the total and soluble expression of LOX, which resulted in the soluble expression of LOX increased by 7 times. Finally, the soluble expression of LOX was 11 times higher with a combinatorial strategy that included both optimized plasmid partition and auto-induction medium. Our work provides a broad, generalizable, and combinatorial strategy for the efficient production of heterologous proteins at elevated temperatures in the E. coli system. KEY POINTS : • Soluble expression of lipoxygenase at 30 °C or higher temperatures is industrially beneficial. • Strategies comprise plasmid partition and optimized auto-induction medium with glucose, lactose, and glycerol as carbon source. • Combinatorial strategy further improved LOX soluble expression at 30 °C and 37 °C.
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Hashem C, Stolterfoht H, Rinnofner C, Steinberger S, Winkler M, Pichler H. Secretion of Pseudomonas aeruginosa Lipoxygenase by Pichia pastoris upon Glycerol Feed. Biotechnol J 2020; 15:e2000089. [PMID: 32749051 DOI: 10.1002/biot.202000089] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/07/2020] [Indexed: 01/17/2023]
Abstract
Pseudomonas aeruginosa lipoxygenase (PaLOX) catalyzes the peroxidation of unsaturated fatty acids. Not only linoleic acid, but also linolenic acid and oleic acid are oxidized. The natural host secretes PaLOX into the periplasmic space. Herein, the aim is to secrete PaLOX to the culture supernatant of Pichia pastoris. Since protein background in the culture supernatant is typically rather low, this strategy allows for almost pure production of PaLOX applicable for the valorization of renewable fatty acids, for example for the production of green leaf volatiles. Using the CAT1 promoter system and the well-established α-factor signal sequence for secretion, methanol- and glycerol-induced secretion are compared and the latter shows four times more LOX activity in the culture supernatant under methanol-free conditions. In addition, secreted PaLOX is purified and the specific activity with enzyme in culture supernatant is compared. Notably, the predominant specific activity is achieved for enzyme in culture supernatant - 11.6 U mg-1 - reaching five times higher specific activity than purified PaLOX.
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Affiliation(s)
- Chiam Hashem
- Austrian Centre of Industrial Biotechnology, Krenngasse 37, Graz, 8010, Austria
- TU Graz, NAWI Graz, BioTechMed Graz, Institute of Molecular Biotechnology, Petersgasse 14, Graz, 8010, Austria
| | - Holly Stolterfoht
- Austrian Centre of Industrial Biotechnology, Krenngasse 37, Graz, 8010, Austria
| | - Claudia Rinnofner
- Austrian Centre of Industrial Biotechnology, Krenngasse 37, Graz, 8010, Austria
- bisy GmbH, Wuenschendorf 292, Hofstaetten, 8200, Austria
| | - Stefan Steinberger
- Austrian Centre of Industrial Biotechnology, Krenngasse 37, Graz, 8010, Austria
| | - Margit Winkler
- Austrian Centre of Industrial Biotechnology, Krenngasse 37, Graz, 8010, Austria
- TU Graz, NAWI Graz, BioTechMed Graz, Institute of Molecular Biotechnology, Petersgasse 14, Graz, 8010, Austria
| | - Harald Pichler
- Austrian Centre of Industrial Biotechnology, Krenngasse 37, Graz, 8010, Austria
- TU Graz, NAWI Graz, BioTechMed Graz, Institute of Molecular Biotechnology, Petersgasse 14, Graz, 8010, Austria
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Lu J, Zhang C, Leong HY, Show PL, Lu F, Lu Z. Overproduction of lipoxygenase from Pseudomonas aeruginosa in Escherichia coli by auto-induction expression and its application in triphenylmethane dyes degradation. J Biosci Bioeng 2020; 129:327-332. [DOI: 10.1016/j.jbiosc.2019.09.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Revised: 08/10/2019] [Accepted: 09/07/2019] [Indexed: 01/28/2023]
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Stolterfoht H, Rinnofner C, Winkler M, Pichler H. Recombinant Lipoxygenases and Hydroperoxide Lyases for the Synthesis of Green Leaf Volatiles. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:13367-13392. [PMID: 31591878 DOI: 10.1021/acs.jafc.9b02690] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Green leaf volatiles (GLVs) are mainly C6- and in rare cases also C9-aldehydes, -alcohols, and -esters, which are released by plants in response to biotic or abiotic stresses. These compounds are named for their characteristic smell reminiscent of freshly mowed grass. This review focuses on GLVs and the two major pathway enzymes responsible for their formation: lipoxygenases (LOXs) and fatty acid hydroperoxide lyases (HPLs). LOXs catalyze the peroxidation of unsaturated fatty acids, such as linoleic and α-linolenic acids. Hydroperoxy fatty acids are further converted by HPLs into aldehydes and oxo-acids. In many industrial applications, plant extracts have been used as LOX and HPL sources. However, these processes are limited by low enzyme concentration, stability, and specificity. Alternatively, recombinant enzymes can be used as biocatalysts for GLV synthesis. The increasing number of well-characterized enzymes efficiently expressed by microbial hosts will foster the development of innovative biocatalytic processes for GLV production.
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Affiliation(s)
- Holly Stolterfoht
- Austrian Centre of Industrial Biotechnology , Petersgasse 14 , 8010 Graz , Austria
| | - Claudia Rinnofner
- Austrian Centre of Industrial Biotechnology , Petersgasse 14 , 8010 Graz , Austria
- bisy e.U. , Wetzawinkel 20 , 8200 Hofstaetten , Austria
| | - Margit Winkler
- Austrian Centre of Industrial Biotechnology , Petersgasse 14 , 8010 Graz , Austria
- Institute of Molecular Biotechnology , TU Graz, NAWI Graz, BioTechMed Graz , Petersgasse 14 , 8010 Graz , Austria
| | - Harald Pichler
- Austrian Centre of Industrial Biotechnology , Petersgasse 14 , 8010 Graz , Austria
- Institute of Molecular Biotechnology , TU Graz, NAWI Graz, BioTechMed Graz , Petersgasse 14 , 8010 Graz , Austria
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Goloshchapova K, Stehling S, Heydeck D, Blum M, Kuhn H. Functional characterization of a novel arachidonic acid 12S-lipoxygenase in the halotolerant bacterium Myxococcus fulvus exhibiting complex social living patterns. Microbiologyopen 2018; 8:e00775. [PMID: 30560563 PMCID: PMC6612559 DOI: 10.1002/mbo3.775] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 10/24/2018] [Accepted: 11/07/2018] [Indexed: 01/24/2023] Open
Abstract
Lipoxygenases are lipid peroxidizing enzymes, which frequently occur in higher plants and mammals. These enzymes are also expressed in lower multicellular organisms but here they are not widely distributed. In bacteria, lipoxygenases rarely occur and evaluation of the currently available bacterial genomes suggested that <0.5% of all sequenced bacterial species carry putative lipoxygenase genes. We recently rescreened the public bacterial genome databases for lipoxygenase-like sequences and identified two novel lipoxygenase isoforms (MF-LOX1 and MF-LOX2) in the halotolerant Myxococcus fulvus. Both enzymes share a low degree of amino acid conservation with well-characterized eukaryotic lipoxygenase isoforms but they involve the catalytically essential iron cluster. Here, we cloned the MF-LOX1 cDNA, expressed the corresponding enzyme as N-terminal hexa-his-tag fusion protein, purified the recombinant enzyme to electrophoretic homogeneity, and characterized it with respect to its protein-chemical and enzymatic properties. We found that M. fulvus expresses a catalytically active intracellular lipoxygenase that converts arachidonic acid and other polyunsaturated fatty acids enantioselectively to the corresponding n-9 hydroperoxy derivatives. The enzyme prefers C20 - and C22 -polyenoic fatty acids but does not exhibit significant membrane oxygenase activity. The possible biological relevance of MF-LOX1 will be discussed in the context of the suggested concepts of other bacterial lipoxygenases.
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Affiliation(s)
- Kateryna Goloshchapova
- Institute of BiochemistryCharité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt‐Universität zu Berlin, and Berlin Institute of HealthBerlinGermany
| | - Sabine Stehling
- Institute of BiochemistryCharité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt‐Universität zu Berlin, and Berlin Institute of HealthBerlinGermany
| | - Dagmar Heydeck
- Institute of BiochemistryCharité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt‐Universität zu Berlin, and Berlin Institute of HealthBerlinGermany
| | | | - Hartmut Kuhn
- Institute of BiochemistryCharité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt‐Universität zu Berlin, and Berlin Institute of HealthBerlinGermany
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An JU, Oh DK. Stabilization and improved activity of arachidonate 11 S-lipoxygenase from proteobacterium Myxococcus xanthus. J Lipid Res 2018; 59:2153-2163. [PMID: 30257932 DOI: 10.1194/jlr.m088823] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 09/14/2018] [Indexed: 12/26/2022] Open
Abstract
Lipoxygenases (LOXs) catalyze the dioxygenation of PUFAs to produce regio- and stereospecific oxygenated fatty acids. The identification of regio- and stereospecific LOXs is important because their specific products are involved in different physiological activities in various organisms. Bacterial LOXs are found only in some proteobacteria and cyanobacteria, and they are not stable in vitro. Here, we used C20 and C22 PUFAs such as arachidonic acid (ARA), eicosapentaenoic acid, and docosahexaenoic acid to identify an 11S-specific LOX from the proteobacterium Myxococcus xanthus and explore its in vitro stability and activity. The activity and stability of M. xanthus ARA 11S-LOX as well as the production of 11S-hydroxyeicosatetraenoic acid from ARA were significantly increased by the addition of phosphatidylcholine, Ca2+, and coactosin-like protein (newly identified in the yeast Rhodosporidium toluroides) as stimulatory factors; in fact, LOX activity in the presence of all three factors increased approximately 3-fold. Our results indicate that these stimulatory factors can be used to increase the activity and stability of bacterial LOX and the production of bioactive hydroxy fatty acids, which can contribute to new academic research.
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Affiliation(s)
- Jung-Ung An
- Department of Bioscience and Biotechnology, Konkuk University, Seoul 05029, South Korea
| | - Deok-Kun Oh
- Department of Bioscience and Biotechnology, Konkuk University, Seoul 05029, South Korea
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Aldrovandi M, Banthiya S, Meckelmann S, Zhou Y, Heydeck D, O'Donnell VB, Kuhn H. Specific oxygenation of plasma membrane phospholipids by Pseudomonas aeruginosa lipoxygenase induces structural and functional alterations in mammalian cells. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1863:152-164. [PMID: 29146531 PMCID: PMC5764228 DOI: 10.1016/j.bbalip.2017.11.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/20/2017] [Accepted: 11/11/2017] [Indexed: 01/18/2023]
Abstract
Pseudomonas aeruginosa is a gram-negative pathogen, which causes life-threatening infections in immunocompromized patients. These bacteria express a secreted lipoxygenase (PA-LOX), which oxygenates free arachidonic acid to 15S-hydro(pero)xyeicosatetraenoic acid. It binds phospholipids at its active site and physically interacts with lipid vesicles. When incubated with red blood cells membrane lipids are oxidized and hemolysis is induced but the structures of the oxygenated membrane lipids have not been determined. Using a lipidomic approach, we analyzed the formation of oxidized phospholipids generated during the in vitro incubation of recombinant PA-LOX with human erythrocytes and cultured human lung epithelial cells. Precursor scanning of lipid extracts prepared from these cells followed by multiple reaction monitoring and MS/MS analysis revealed a complex mixture of oxidation products. For human red blood cells this mixture comprised forty different phosphatidylethanolamine and phosphatidylcholine species carrying oxidized fatty acid residues, such as hydroxy-octadecadienoic acids, hydroxy- and keto-eicosatetraenoic acid, hydroxy-docosahexaenoic acid as well as oxygenated derivatives of less frequently occurring polyenoic fatty acids. Similar oxygenation products were also detected when cultured lung epithelial cells were employed but here the amounts of oxygenated lipids were smaller and under identical experimental conditions we did not detect major signs of cell lysis. However, live imaging indicated an impaired capacity for trypan blue exclusion and an augmented mitosis rate. Taken together these data indicate that PA-LOX can oxidize the membrane lipids of eukaryotic cells and that the functional consequences of this reaction strongly depend on the cell type.
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Affiliation(s)
- Maceler Aldrovandi
- Systems Immunity Research Institute, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK
| | - Swathi Banthiya
- Institute of Biochemistry, Charite - University Medicine Berlin, Charitéplatz 1, D-10117 Berlin, Germany
| | - Sven Meckelmann
- Systems Immunity Research Institute, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK
| | - You Zhou
- Systems Immunity Research Institute, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK
| | - Dagmar Heydeck
- Institute of Biochemistry, Charite - University Medicine Berlin, Charitéplatz 1, D-10117 Berlin, Germany
| | - Valerie B O'Donnell
- Systems Immunity Research Institute, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK.
| | - Hartmut Kuhn
- Institute of Biochemistry, Charite - University Medicine Berlin, Charitéplatz 1, D-10117 Berlin, Germany.
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Banthiya S, Kalms J, Galemou Yoga E, Ivanov I, Carpena X, Hamberg M, Kuhn H, Scheerer P. Structural and functional basis of phospholipid oxygenase activity of bacterial lipoxygenase from Pseudomonas aeruginosa. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1681-1692. [PMID: 27500637 DOI: 10.1016/j.bbalip.2016.08.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 07/29/2016] [Accepted: 08/03/2016] [Indexed: 01/18/2023]
Abstract
Pseudomonas aeruginosa expresses a secreted LOX-isoform (PA-LOX, LoxA) capable of oxidizing polyenoic fatty acids to hydroperoxy derivatives. Here we report high-level expression of this enzyme in E. coli and its structural and functional characterization. Recombinant PA-LOX oxygenates polyenoic fatty acids including eicosapentaenoic acid and docosahexaenoic acid to the corresponding (n-6)S-hydroperoxy derivatives. This reaction involves abstraction of the proS-hydrogen from the n-8 bisallylic methylene. PA-LOX lacks major leukotriene synthase activity but converts 5S-HETE and 5S,6R/S-DiHETE to anti-inflammatory and pro-resolving lipoxins. It also exhibits phospholipid oxygenase activity as indicated by the formation of a specific pattern of oxygenation products from different phospholipid subspecies. Multiple mutagenesis studies revealed that PA-LOX does not follow classical concepts explaining the reaction specificity of mammalian LOXs. The crystal structure of PA-LOX was solved with resolutions of up to 1.48Å and its polypeptide chain is folded as single domain. The substrate-binding pocket consists of two fatty acid binding subcavities and lobby. Subcavity-1 contains the catalytic non-heme iron. A phosphatidylethanolamine molecule occupies the substrate-binding pocket and its sn1 fatty acid is located close to the catalytic non-heme iron. His377, His382, His555, Asn559 and the C-terminal Ile685 function as direct iron ligands and a water molecule (hydroxyl) completes the octahedral ligand sphere. Although the biological relevance of PA-LOX is still unknown its functional characteristics (lipoxin synthase activity) implicate this enzyme in a bacterial evasion strategy aimed at downregulating the hosts' immune system.
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Affiliation(s)
- Swathi Banthiya
- Institut für Biochemie, Charité - Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany
| | - Jacqueline Kalms
- Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography and Signal Transduction, Charité - Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany
| | - Etienne Galemou Yoga
- Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography and Signal Transduction, Charité - Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany
| | - Igor Ivanov
- Institut für Biochemie, Charité - Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany
| | - Xavi Carpena
- Institut de Biologia Molecular de Barcelona (IBMB-CSIC), Parc Científic de Barcelona, 08028 Barcelona, Spain; XALOC beamline, ALBA synchrotron (CELLS), 08290 Cerdanyola del Vallès, Spain
| | - Mats Hamberg
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Hartmut Kuhn
- Institut für Biochemie, Charité - Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany.
| | - Patrick Scheerer
- Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography and Signal Transduction, Charité - Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany.
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Secreted lipoxygenase from Pseudomonas aeruginosa exhibits biomembrane oxygenase activity and induces hemolysis in human red blood cells. Arch Biochem Biophys 2015; 584:116-24. [PMID: 26361973 DOI: 10.1016/j.abb.2015.09.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 09/02/2015] [Accepted: 09/02/2015] [Indexed: 01/18/2023]
Abstract
Pseudomonas aeruginosa (PA) expresses a secreted lipoxygenase (LOX), which oxygenates free arachidonic acid predominantly to 15S-H(p)ETE. The enzyme is capable of binding phospholipids at its active site and physically interacts with model membranes. However, its membrane oxygenase activity has not been quantified. To address this question, we overexpressed PA-LOX as intracellular his-tag fusion protein in Escherichia coli, purified it to electrophoretic homogeneity and compared its biomembrane oxygenase activity with that of rabbit ALOX15. We found that both enzymes were capable of oxygenating mitochondrial membranes to specific oxygenation products and 13S-H(p)ODE and 15S-H(p)ETE esterified to phosphatidylcholine and phosphatidylethanolamine were identified as major oxygenation products. When normalized to similar linoleic acid oxygenase activity, the rabbit enzyme exhibited a much more effective mitochondrial membrane oxygenase activity. In contrast, during long-term incubations (24 h) with red blood cells PA-LOX induced significant (50%) hemolysis whereas rabbit ALOX15 was more or less ineffective. These data indicate the principle capability of PA-LOX of oxygenating membrane bound phospholipids which is likely to alter the barrier function of the biomembranes. Although the membrane oxygenase activity was lower than the fatty acid oxygenase activity of PA-LOX red blood cell membrane oxygenation might be of biological relevance for P. aeruginosa septicemia.
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Heshof R, de Graaff LH, Villaverde JJ, Silvestre AJ, Haarmann T, Dalsgaard TK, Buchert J. Industrial potential of lipoxygenases. Crit Rev Biotechnol 2015; 36:665-74. [DOI: 10.3109/07388551.2015.1004520] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Ruud Heshof
- Laboratory of Systems and Synthetic Biology, Wageningen University, Wageningen, The Netherlands,
| | - Leo H. de Graaff
- Laboratory of Systems and Synthetic Biology, Wageningen University, Wageningen, The Netherlands,
| | - Juan J. Villaverde
- Department of Chemistry, CICECO, University of Aveiro, Aveiro, Portugal,
- On leave to INIA, DTEVPF, Plant Protection Products Unit, Ctra. de La Coruña, Madrid, Spain,
| | | | | | - Trine K. Dalsgaard
- Department of Food Sciences, Faculty of Science and Technology, Aarhus University, Tjele, Denmark, and
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Xu Z, Liu S, Lu X, Rao S, Kang Z, Li J, Wang M, Chen J. Thermal inactivation of a recombinant lipoxygenase from Pseudomonas aeruginosa BBE in the absence and presence of additives. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2014; 94:1753-1757. [PMID: 24272925 DOI: 10.1002/jsfa.6487] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 11/14/2013] [Accepted: 11/22/2013] [Indexed: 06/02/2023]
Abstract
BACKGROUND Bacterial lipoxygenase (EC 1.13.11.12, LOX) is an important enzyme used as a brightener and strengthening agent during breadmaking. In this study, thermal inactivation of a recombinant LOX of Pseudomonas aeruginosa BBE was characterized by kinetic and thermodynamic analysis in the absence and presence of additives. RESULTS As the heating temperature increased from 25 to 55 °C, the thermal inactivation rate (k) values for LOX without the additives ranged from 0.0407 to 0.2627 min(-1), while the half-life (t1/2) values were between 17.08 and 3.25 min. The activation energy (ΔE) values were increased with rise in heating temperatures from 13.26 to 108.9 kJ mol(-1) . Separate tests at 45 °C in the presence of additives (polyols, sugars and ions) at specific concentrations showed that xylitol (1 mol L(-1)) was the most effective stabilizer for recombinant LOX and increased the t1/2 value by 297%. CONCLUSION Recombinant LOX was sensitive to heat treatment, and addition of polyols, sugars and ions could enhance its thermal stability. Our findings may provide useful information for stabilizing emerging bacterial LOXs.
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Affiliation(s)
- Zhi Xu
- Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 214122, Wuxi, China
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Abstract
A bacterial lipoxygenase (LOX) shows a deuterium kinetic isotope effect (KIE) that is similar in magnitude and temperature dependence to the very large KIE of eukaryotic LOXs. This occurs despite the evolutionary distance, an ~25% smaller catalytic domain, and an increase in Ea of ~11 kcal/mol. Site-specific mutagenesis leads to a protein variant with an Ea similar to that of the prototypic plant LOX, providing possible insight into the origin of evolutionary differences. These findings, which extend the phenomenon of hydrogen tunneling to a prokaryotic LOX, are discussed in the context of a role for protein size and/or flexibility in enzymatic hydrogen tunneling.
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Affiliation(s)
- Cody A Marcus Carr
- Department of Chemistry, ‡Department of Molecular and Cell Biology, and §California Institute for Quantitative Biosciences (QB3), University of California , Berkeley, California 94720, United States
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Garreta A, Val-Moraes SP, García-Fernández Q, Busquets M, Juan C, Oliver A, Ortiz A, Gaffney BJ, Fita I, Manresa À, Carpena X. Structure and interaction with phospholipids of a prokaryotic lipoxygenase from Pseudomonas aeruginosa. FASEB J 2013; 27:4811-21. [PMID: 23985801 DOI: 10.1096/fj.13-235952] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Lipoxygenases (LOXs), which are essential in eukaryotes, have no confirmed function in prokaryotes that are devoid of polyunsaturated fatty acids. The structure of a secretable LOX from Pseudomonas aeruginosa (Pa_LOX), the first available from a prokaryote, presents significant differences with respect to eukaryotic LOXs, including a cluster of helices acting as a lid to the active center. The mobility of the lid and the structural variability of the N-terminal region of Pa_LOX was confirmed by comparing 2 crystal forms. The binding pocket contains a phosphatidylethanolamine phospholipid with branches of 18 (sn-1) and 14/16 (sn-2) carbon atoms in length. Carbon atoms from the sn-1 chain approach the catalytic iron in a manner that sheds light on how the enzymatic reaction might proceed. The findings in these studies suggest that Pa_LOX has the capacity to extract and modify unsaturated phospholipids from eukaryotic membranes, allowing this LOX to play a role in the interaction of P. aeruginosa with host cells.
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Affiliation(s)
- Albert Garreta
- 1Institut de Biologia Molecular, Parc Científic de Barcelona, Baldiri Reixac 10, 08028 Barcelona, Spain.
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He Q, Hong K, Zou R, Liao F, Cui S, Zhang E, Huang M. The role of jasmonic acid and lipoxygenase in propylene-induced chilling tolerance on banana fruit. Eur Food Res Technol 2013. [DOI: 10.1007/s00217-013-2080-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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17
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Kim KR, Oh DK. Production of hydroxy fatty acids by microbial fatty acid-hydroxylation enzymes. Biotechnol Adv 2013; 31:1473-85. [PMID: 23860413 DOI: 10.1016/j.biotechadv.2013.07.004] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 07/03/2013] [Accepted: 07/06/2013] [Indexed: 10/26/2022]
Abstract
Hydroxy fatty acids are widely used in chemical, food, and cosmetic industries as starting materials for the synthesis of polymers and as additives for the manufacture of lubricants, emulsifiers, and stabilizers. They have antibiotic, anti-inflammatory, and anticancer activities and therefore can be applied for medicinal uses. Microbial fatty acid-hydroxylation enzymes, including P450, lipoxygenase, hydratase, 12-hydroxylase, and diol synthase, synthesize regio-specific hydroxy fatty acids. In this article, microbial fatty acid-hydroxylation enzymes, with a focus on region-specificity and diversity, are summarized and the production of mono-, di-, and tri-hydroxy fatty acids is introduced. Finally, the production methods of regio-specific and diverse hydroxy fatty acids, such as gene screening, protein engineering, metabolic engineering, and combinatory biosynthesis, are suggested.
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Affiliation(s)
- Kyoung-Rok Kim
- Department of Bioscience and Biotechnology, Konkuk University, 1 Hwayang-Dong Gwangjin-Gu, Seoul 143-701, Republic of Korea
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18
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Joo YC, Oh DK. Lipoxygenases: Potential starting biocatalysts for the synthesis of signaling compounds. Biotechnol Adv 2012; 30:1524-32. [DOI: 10.1016/j.biotechadv.2012.04.004] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 03/26/2012] [Accepted: 04/10/2012] [Indexed: 12/11/2022]
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19
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Lu X, Zhang J, Liu S, Zhang D, Xu Z, Wu J, Li J, Du G, Chen J. Overproduction, purification, and characterization of extracellular lipoxygenase of Pseudomonas aeruginosa in Escherichia coli. Appl Microbiol Biotechnol 2012; 97:5793-800. [PMID: 23064455 DOI: 10.1007/s00253-012-4457-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 09/16/2012] [Accepted: 09/20/2012] [Indexed: 10/27/2022]
Abstract
Lipoxygenase (LOX; EC 1.13.11.12,) is an enzyme that is widely used in food industry to improve aroma, rheological, or baking properties of foods. In this study, we described the expression and characterization of Pseudomonas aeruginosa LOX in Escherichia coli. The recombinant LOX was successfully expressed and secreted by E. coli using its endogenous signal peptide. When induced with 1 mM isopropyl β-D-1-thiogalactopyranoside (final concentration) at 20 °C for 47 h, the titer of the recombinant enzyme reached 3.89 U/mL. In order to characterize the catalytic properties, the recombinant LOX was purified to homogeneity on Q High Performance and Mono Q5/50GL sequentially. The molecular weight of the LOX was estimated as 70 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The Km and Vmax of the recombinant enzyme were 48.9 μM and 0.226 μmol/min, respectively. The purified enzyme exhibited a maximum activity at 25 °C and pH 7.5. High-performance liquid chromatography analysis of the linoleic acid hydroperoxides produced by recombinant LOX revealed that the LOX from P. aeruginosa falls into linoleic acid 13(S)-LOX. To the best of our knowledge, this is the first report on the overexpression of extracellular LOX in microorganisms, and the achieved LOX yield is the highest ever reported.
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Affiliation(s)
- Xinyao Lu
- Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China
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20
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Bae JH, Hou CT, Kim HR. Thermostable lipoxygenase is a key enzyme in the conversion of linoleic acid to trihydroxy-octadecenoic acid by Pseudomonas aeruginosa PR3. BIOTECHNOL BIOPROC E 2011. [DOI: 10.1007/s12257-010-0273-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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21
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Martínez E, Hamberg M, Busquets M, Díaz P, Manresa A, Oliw EH. Biochemical characterization of the oxygenation of unsaturated fatty acids by the dioxygenase and hydroperoxide isomerase of Pseudomonas aeruginosa 42A2. J Biol Chem 2010; 285:9339-9345. [PMID: 20075076 PMCID: PMC2843182 DOI: 10.1074/jbc.m109.078147] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 12/23/2009] [Indexed: 01/14/2023] Open
Abstract
We have studied oxygenation of fatty acids by cell extract of Pseudomonas aeruginosa 42A2. Oleic acid ((9Z)-18:1) was transformed to (10S)-hydroperoxy-(8E)-octadecenoic acid ((10S)-HPOME) and to (7S,10S)-dihydroxy-(8E)-octadecenoic acid (7,10-DiHOME). Experiments under oxygen-18 showed that 7,10-DiHOME contained oxygen from air and was formed sequentially from (10S)-HPOME by isomerization. (10R)-HPOME was not isomerized. The (10S)-dioxygenase and hydroperoxide isomerase activities co-eluted on ion exchange chromatography and on gel filtration with an apparent molecular size of approximately 50 kDa. 16:1n-7, 18:2n-6, and 20:1n-11 were also oxygenated to 7,10-dihydroxy fatty acids, and (8Z)-18:1 was oxygenated to 6,9-dihydroxy-(7E)-octadecenoic acid. A series of fatty acids with the double bond positioned closer to ((6Z)-18:1, (5Z,9Z)-18:2) or more distant from the carboxyl group ((11Z)-, (13Z)-, and (15Z)-18:1) were poor substrates. The oxygenation mechanism was studied with [7S-(2)H]18:1n-9, [7R-(2)H]18:2n-6, and [8R-(2)H]18:2n-6 as substrates. The pro-R hydrogen at C-8 was lost in the biosynthesis of (10S)-HPODE, whereas the pro-S hydrogen was lost and the pro-R hydrogen was retained at C-7 during biosynthesis of the 7,10-dihydroxy metabolites. Analysis of the fatty acid composition of P. aeruginosa revealed relatively large amounts of (9E/Z)-16:1 and (11E/Z)-18:1 and only traces of 18:1n-9. We found that (11Z)-18:1 (vaccenic acid) was transformed to (11S,14S)-dihydroxy-(12E)-octadecenoic acid and to a mixture of 11- and 12-HPOME, possibly due to reverse orientation of (11Z)-18:1 at the active site compared with oleic acid. The reaction mechanism of the hydroperoxide isomerase suggests catalytic similarities to cytochrome P450.
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Affiliation(s)
- Eriel Martínez
- Division of Biochemical Pharmacology, Department of Pharmaceutical Bioscience, Uppsala Biomedical Center, P.O. Box 591, SE-751 24 Uppsala, Sweden; Laboratori de Microbiologia, Facultat de Farmàcia, Barcelona E-08028, Spain
| | - Mats Hamberg
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Montse Busquets
- Departament de Bioquimica i Biologia Molecular, Universitat de Barcelona, Barcelona E-08028, Spain
| | - Pilar Díaz
- Laboratori de Microbiologia, Facultat de Biologia, Barcelona E-08028, Spain
| | - Angeles Manresa
- Laboratori de Microbiologia, Facultat de Farmàcia, Barcelona E-08028, Spain
| | - Ernst H Oliw
- Division of Biochemical Pharmacology, Department of Pharmaceutical Bioscience, Uppsala Biomedical Center, P.O. Box 591, SE-751 24 Uppsala, Sweden.
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22
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Palmieri-Thiers C, Canaan S, Brunini V, Lorenzi V, Tomi F, Desseyn JL, Garscha U, Oliw EH, Berti L, Maury J. A lipoxygenase with dual positional specificity is expressed in olives (Olea europaea L.) during ripening. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:339-46. [PMID: 19268561 DOI: 10.1016/j.bbalip.2009.02.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Revised: 01/09/2009] [Accepted: 02/12/2009] [Indexed: 11/26/2022]
Abstract
Plant lipoxygenases (LOXs) are a class of widespread dioxygenases catalysing the hydroperoxidation of polyunsaturated fatty acids. Although multiple isoforms of LOX have been detected in a wide range of plants, their physiological roles remain to be clarified. With the aim to clarify the occurrence of LOXs in olives and their contribution to the elaboration of the olive oil aroma, we cloned and characterized the first cDNA of the LOX isoform which is expressed during olive development. The open reading frame encodes a polypeptide of 864 amino acids. This olive LOX is a type-1 LOX which shows a high degree of identity at the peptide level towards hazelnut (77.3%), tobacco (76.3%) and almond (75.5%) LOXs. The recombinant enzyme shows a dual positional specificity, as it forms both 9- and 13-hydroperoxide of linoleic acid in a 2:1 ratio, and would be defined as 9/13-LOX. Although a LOX activity was detected throughout the olive development, the 9/13-LOX is mainly expressed at late developmental stages. Our data suggest that there are at least two Lox genes expressed in black olives, and that the 9/13-LOX is associated with the ripening and senescence processes. However, due to its dual positional specificity and its expression pattern, its contribution to the elaboration of the olive oil aroma might be considered.
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Affiliation(s)
- Cynthia Palmieri-Thiers
- Université de Corse, CNRS UMR6134 SPE, Laboratoire de Biochimie et Biologie Moléculaire Végétales, campus Grimaldi, BP52, 20250 Corte, France
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23
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Pseudomonas aeruginosa twitching motility-mediated chemotaxis towards phospholipids and fatty acids: specificity and metabolic requirements. J Bacteriol 2008; 190:4038-49. [PMID: 18390654 DOI: 10.1128/jb.00129-08] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa demonstrates type IV pilus-mediated directional twitching motility up a gradient of phosphatidylethanolamine (PE). Only one of four extracellular phospholipases C of P. aeruginosa (i.e., PlcB), while not required for twitching motility per se, is required for twitching-mediated migration up a gradient of PE or phosphatidylcholine. Whether other lipid metabolism genes are associated with this behavior was assessed by analysis of transcription during twitching up a PE gradient in comparison to transcription during twitching in the absence of any externally applied phospholipid. Data support the hypothesis that PE is further degraded and that the long-chain fatty acid (LCFA) moieties of PE are completely metabolized via beta-oxidation and the glyoxylate shunt. It was discovered that P. aeruginosa exhibits twitching-mediated chemotaxis toward unsaturated LCFAs (e.g., oleic acid), but not saturated LCFAs (e.g., stearic acid) of corresponding lengths. Analysis of mutants that are deficient in glyoxylate shunt enzymes, specifically isocitrate lyase (DeltaaceA) and malate synthase (DeltaaceB), suggested that the complete metabolism of LCFAs through this pathway was required for the migration of P. aeruginosa up a gradient of PE or unsaturated LCFAs. At this point, our data suggested that this process should be classified as energy taxis. However, further evaluation of the ability of the DeltaaceA and DeltaaceB mutants to migrate up a gradient of PE or unsaturated LCFAs in the presence of an alternative energy source clearly indicated that metabolism of LCFAs for energy is not required for chemotaxis toward these compounds.
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Abstract
The dioxygenation of PUFAs (polyunsaturated fatty acids) in plants is mainly catalysed by members of the LOX (lipoxygenase) enzyme family. LOX products may be further metabolized, and are known as signalling substances in plant development and in responses to wounding and pathogen attack. In contrast with the situation in eukaryotes, information on the relevance of lipid peroxide metabolism in prokaryotic organisms is scarce. Therefore, we aimed to analyse LOXs and oxylipin patterns of cyanobacterial origin. A search of the genomic sequence of the cyanobacterium Nostoc sp. PCC 7120 suggested an open reading frame encoding a putative LOX named NspLOX that harboured an N-terminal extension. Individual analysis of recombinant C-terminal domain revealed enzymatic activity as a linoleate (9R)-LOX. Analysis of the full-length NspLOX protein, however, revealed linoleate diol synthase activity, generating (10E,12E)-9,14-dihydroxy-10,12-octadecadienoic acid as the main product from LA (linoleic acid) and (10E,12E,14E)-9,16-dihydroxy-10,12,14-octadecatrienoic acid as the main product from ALA (α-LA) substrates respectively, with ALA as preferred substrate. The enzyme exhibited a broad pH optimum between pH 7 and pH 10. Soluble extracts of Nostoc sp. contain more 9-LOX-derived hydroperoxides in sonified than in non-sonified cells, but products of full-length NspLOX were not detectable under the conditions used. As no other LOX-like sequence was identified in the genome of Nostoc sp. PCC 7120, the results presented suggest that (9R)-LOX-derived oxylipins may represent the endogenous products of NspLOX. Based on the biochemical results of NspLOX, we suggest that this bifunctional enzyme may represent a more ancient way to control the intracellular amount of oxylipins in this cyanobacterium.
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25
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Koeduka T, Kajiwara T, Matsui K. Cloning of lipoxygenase genes from a cyanobacterium, Nostoc punctiforme, and its expression in Eschelichia coli. Curr Microbiol 2007; 54:315-9. [PMID: 17375360 DOI: 10.1007/s00284-006-0512-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2006] [Accepted: 11/22/2006] [Indexed: 10/23/2022]
Abstract
Oxylipin metabolism represents one of the important hormonal and defensive mechanisms employed by plants, algae, or animals. It begins mostly with the reaction of lipoxygenases (LOXs), which catalyze the oxygenation of polyunsaturated fatty acids to form the corresponding hydroperoxides. At present, little information about LOXs in cyanobacteria has been reported. Herein, we report the first isolation of two LOX genes (NpLOX1 and NpLOX2) from a cyanobacterium, Nostoc punctiforme ATCC29133. Incubations of recombinant NpLOX1 and NpLOX2 proteins expressed in Eschelichia coli with linoleic acid resulted in the predominant formation of linoleic acid 13-S-hydroperoxide. Other C18 and C20 fatty acids could also be substrates for NpLOX enzymes. Phylogenetic analysis of NpLOX sequences showed that the NpLOX enzymes shared a high homology with LOX sequence of a bacterial pathogen, Pseudomonas aeruginosa, and these bacterial LOXs formed a subfamily distinct from those of plants, algae, and mammals.
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Affiliation(s)
- Takao Koeduka
- Department of Biological Chemistry, Faculty of Agriculture, and Applied Molecular Bioscience, Graduate School of Medicine, Yamaguchi University, Yoshida 1677-1, Yamaguchi, 753-8515, Japan
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Youn B, Sellhorn GE, Mirchel RJ, Gaffney BJ, Grimes HD, Kang C. Crystal structures of vegetative soybean lipoxygenase VLX-B and VLX-D, and comparisons with seed isoforms LOX-1 and LOX-3. Proteins 2006; 65:1008-20. [PMID: 17022084 PMCID: PMC2777516 DOI: 10.1002/prot.21182] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The lipoxygenase family of lipid-peroxidizing, nonheme iron dioxygenases form products that are precursors for diverse physiological processes in both plants and animals. In soybean (Glycine max), five vegetative isoforms, VLX-A, VLX-B, VLX-C, VLX-D, VLX-E, and four seed isoforms LOX-1, LOX-2, LOX-3a, LOX-3b have been identified. In this study, we determined the crystal structures of the substrate-free forms of two major vegetative isoforms, with distinct enzymatic characteristics, VLX-B and VLX-D. Their structures are similar to the two seed isoforms, LOX-1 and LOX-3, having two domains with similar secondary structural elements: a beta-barrel N-terminal domain containing highly flexible loops and an alpha-helix-rich C-terminal catalytic domain. Detailed comparison of the structures of these two vegetative isoforms with the structures of LOX-1 and LOX-3 reveals important differences that help explain distinct aspects of the activity and positional specificity of these enzymes. In particular, the shape of the three branches of the internal subcavity, corresponding to substrate-binding and O(2) access, differs among the isoforms in a manner that reflects the differences in positional specificities.
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Affiliation(s)
- Buhyun Youn
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4660
| | - George E. Sellhorn
- Graduate program in Molecular Plant Sciences, Washington State University, Pullman, Washington 99164-6340
| | - Ryan J. Mirchel
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4660
| | - Betty J. Gaffney
- Biological Sciences Department, BIO Unit I, Florida State University, Tallahassee, Florida 32306-4370
| | - Howard D. Grimes
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4660
- Graduate program in Molecular Plant Sciences, Washington State University, Pullman, Washington 99164-6340
| | - ChulHee Kang
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4660
- Graduate program in Molecular Plant Sciences, Washington State University, Pullman, Washington 99164-6340
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