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1.
Molecular enzymology of lipoxygenases 总被引:1,自引:0,他引:1
Igor Ivanov Katharina Hofheinz Valerie B. O’Donnell Matthias Walther 《Archives of biochemistry and biophysics》2010,503(2):161-174
Lipoxygenases (LOXs) are lipid peroxidizing enzymes, implicated in the pathogenesis of inflammatory and hyperproliferative diseases, which represent potential targets for pharmacological intervention. Although soybean LOX1 was discovered more than 60 years ago, the structural biology of these enzymes was not studied until the mid 1990s. In 1993 the first crystal structure for a plant LOX was solved and following this protein biochemistry and molecular enzymology became major fields in LOX research. This review focuses on recent developments in molecular enzymology of LOXs and summarizes our current understanding of the structural basis of LOX catalysis. Various hypotheses explaining the reaction specificity of different isoforms are critically reviewed and their pros and cons briefly discussed. Moreover, we summarize the current knowledge of LOX evolution by profiling the existence of LOX-related genomic sequences in the three kingdoms of life. Such sequences are found in eukaryotes and bacteria but not in archaea. Although the biological role of LOXs in lower organisms is far from clear, sequence data suggests that this enzyme family might have evolved shortly after the appearance of atmospheric oxygen on earth. 相似文献
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Lipid oxidation is a common metabolic reaction in all biological systems, appearing in developmentally regulated processes and as response to abiotic and biotic stresses. Products derived from lipid oxidation processes are collectively named oxylipins. Initial lipid oxidation may either occur by chemical reactions or is derived from the action of enzymes. In plants this reaction is mainly catalyzed by lipoxygenase (LOXs) enzymes and during recent years analysis of different plant LOXs revealed insights into their enzyme mechanism. This review aims at giving an overview of concepts explaining the catalytic mechanism of LOXs as well as the different regio- and stereo-specificities of these enzymes. 相似文献
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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. 相似文献
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Biochemical and molecular characterization of hazelnut (Corylus avellana) seed lipoxygenases. 总被引:1,自引:0,他引:1
Angelo Santino Angelo De Paolis Antonia Gallo Angela Quarta Rod Casey Giovanni Mita 《European journal of biochemistry》2003,270(21):4365-4375
Plant lipoxygenases (LOXs) are a class of dioxygenases which display diverse functions in several physiological processes such as growth, development and response to biotic and abiotic stresses. Even though LOXs have been characterized from several plant species, the physiological role of seed LOXs is still unclear. With the aim to better clarify the occurrence of LOXs and their influence on hazelnut seed quality, we carried out the biochemical and molecular characterization of the main LOX isoforms expressed during seed development. A genomic clone containing a complete LOX gene was isolated and fully characterized. The 9887 bp sequence reported contains an open reading frame of 5334 bp encoding a putative polypeptide of 99 kDa. Semiquantitative RT-PCR carried out from RNAs extracted from seeds at different maturation stages showed that LOXs are mainly expressed at early developmental stages. These results were confirmed by LOX activity assays. Biochemical characterization of the reaction products of the hazelnut LOX indicated that it is a 9-LOX. Two cDNAs were isolated by RT-PCR carried out on total RNA from immature hazelnut seeds. Sequence analysis indicated that the two cDNAs are highly homologous (91.9% degree of identity) and one of these corresponded exactly to the genomic clone. The deduced amino acid sequences of the hazelnut LOXs showed that they are closely related to a previously reported almond LOX (79.5% identity) and, to a lesser extent, to some LOXs involved in plant responses to pathogens (cotton and tobacco LOXs, 75.5 and 74.6% identity, respectively). The physiological role of hazelnut LOXs and their role in influencing seed quality are also discussed. 相似文献
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The oxygenation of polyunsaturated fatty acids such as arachidonic and linoleic acid through lipoxygenases (LOXs) and cyclooxygenases (COXs) leads to the production of bioactive lipids that are important both in the induction of acute inflammation and its resolution. Amongst the several isoforms of LOX that are expressed in mammals, 15‐LOX‐1 was shown to be important both in the context of inflammation, being expressed in cells of the immune system, and in epithelial cells where the enzyme has been shown to crosstalk with a number of important signalling pathways. This review looks into the latest developments in understanding the role of 15‐LOX‐1 in different disease states with emphasis on the emerging role of the enzyme in the tumour microenvironment as well as a newly re‐discovered form of cell death called ferroptosis. We also discuss future perspectives on the feasibility of use of this protein as a target for therapeutic interventions. 相似文献
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Plant lipoxygenases (LOXs; EC 1.13.11.12) catalyse the oxygenation of polyunsaturated fatty acids, linoleic (18:2) and α-linolenic acid (18:3(n-3)) and are involved in processes such as stress responses and development. Depending on the regio-specificity of a LOX, the incorporation of molecular oxygen leads to formation of 9- or 13-fatty acid hydroperoxides, which are used by LOX itself as well as by members of at least six different enzyme families to form a series of biologically active molecules, collectively called oxylipins. The best characterised oxylipins are the jasmonates: jasmonic acid (JA) and its isoleucine conjugate that are signalling compounds in vegetative and propagative plant development. In several types of nitrogen-fixing root nodules, LOX expression and/or activity is induced during nodule development. Allene oxide cyclase (AOC), a committed enzyme of the JA biosynthetic pathway, has been shown to localise to plastids of nodules of one legume and two actinorhizal plants, Medicago truncatula, Datisca glomerata and Casuarina glauca, respectively. Using an antibody that recognises several types of LOX interspecifically, LOX protein levels were compared in roots and nodules of these plants, showing no significant differences and no obvious nodule-specific isoforms. A comparison of the cell-specific localisation of LOXs and AOC led to the conclusion that (i) only cytosolic LOXs were detected although it is generally assumed that the (13S)-hydroperoxy α-linolenic acid for JA biosynthesis is produced in the plastids, and (ii) in cells of the nodule vascular tissue that contain AOC, no LOX protein could be detected. 相似文献
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Almerinda Di Venere Eleonora Nicolai Igor Ivanov Enrico Dainese Susan Adel B.C. Angelucci Hartmut Kuhn Mauro Maccarrone Giampiero Mei 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2014,1841(1):1-10
Lipoxygenases (LOXs) are lipid-peroxidizing enzymes that are involved in the metabolism of polyunsaturated fatty acids. Their biological activity includes a membrane binding process whose molecular details are not completely understood. The mechanism of enzyme–membrane interactions is thought to involve conformational changes at the level of the protein tertiary structure, and the extent of such alterations depends on the degree of structural flexibility of the different LOX isoforms. In this study, we have tested the resilience properties of a plant and a mammalian LOX, by using high pressure fluorescence measurements at different temperatures. The binding of LOXs to the lipid bilayer has been characterized using both large and giant unilamellar vesicles and electron transfer particles (inner mitochondrial membranes) as model membranes. The data indicate that the degree of LOXs' flexibility is strictly dependent on the two distinct N- and C-terminal domains that characterize the 3D structure of these enzymes. Furthermore, they demonstrate that increasing the rigidity of protein scaffolding by the presence of an active site ligand impairs the membrane binding ability of LOXs. These findings provide evidence that the amphitropic nature of LOXs is finely tuned by the interaction of the substrate with the residues of the active site, suggesting new strategies for the design of enzyme inhibitors. 相似文献
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Recent findings in our laboratory suggested that in citrus cells the salt induction of phospholipid hydroperoxide glutathione
peroxidase, an enzyme active in cellular antioxidant defense, is mediated by the accumulation of hydroperoxides. Production
of hydroperoxides occurs as a result of non-enzymatic auto-oxidation or via the action of lipoxygenases (LOXs). In an attempt
to resolve the role of LOX activity in the accumulation of peroxides we analyzed the expression of this protein under stress
conditions and in cells of Citrus sinensis L. differing in sensitivity to salt. Lipoxygenase expression was induced very rapidly only in the salt-tolerant cells and
in a transient manner. The induction was specific to salt stress and did not occur with other osmotic-stress-inducing agents,
such as polyethylene glycol or mannitol, or under hot or cold conditions, or in the presence of abscisic acid. The induction
was eliminated by the antioxidants dithiothreitol and kaempferol, thus once more establishing a correlation between salt and
oxidative stresses. Analyses of both in vitro and in vivo products of LOX revealed a specific 9-LOX activity, and a very fast
reduction of the hydroperoxides to the corresponding hydroxy derivatives. This suggests that one of the metabolites further
downstream in the reductase pathway may play a key role in triggering defense responses against salt stress.
Received: 3 February 2000 / Accepted: 13 June 2000 相似文献
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Fungal peroxidases: molecular aspects and applications 总被引:9,自引:0,他引:9
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Background
Lipoxygenase (LOXs) is a large family of plant enzymes that catalyse the hydroperoxidation of free polyunsaturated fatty acids into diverse biologically active compounds, collectively named phyto-oxylipins. Although multiple isoforms of LOXs have been identified in a wide range of annual herbaceous plants, the genes encoding these enzymes in perennial woody plants have not received as much attention. In Camellia sinensis (L.) O. Kuntze, no LOX gene of any type has been isolated, and its possible role in tea plant development, senescence, and defence reaction remains unknown. The present study describes the isolation, characterization, and expression of the first tea plant LOX isoform, namely CsLOX1, and seeks to clarify the pattern of its expression in the plant's defence response as well as in flower opening and senescence. 相似文献15.
Auxin [α-naphthaleneacetic acid (NAA) or indole-3-acetic acid] can induce the expression of lipoxygenases (LOXs) in cultured
immature zygotic embryo cotyledons of soybean [Glycine max. (L.) Merr]. These auxin-induced LOXs are different from those normally expressed in seeds but have the same isoelectric
points (pI) as those found in seedlings. The pIs of the two seedling LOXs were determined to be 5.09 and 5.23. One of the
auxin-induced LOXs has the same pI (5.09) and molecular mass (94 kDa) as seedling LOX4. The partial amino acid sequences from
the purified NAA-induced pI-5.09 LOX are identical to those of LOX4. RNA protection assays showed that NAA induces the expression
of LOX4 and LOX5 mRNAs in cultured embryo cotyledons where they are not normally expressed. Soybean genotypes with a polymorphic
variant of LOX4 in hypocotyls showed the same variation as NAA-induced LOXs in the embryo cotyledons. These results demonstrate
that the NAA-induced pI-5.09 LOX is seedling LOX4 and also suggest that auxin might be directly or indirectly involved in
seedling LOX expression during seed germination.
Received: 10 January 2000 / Revision received: 16 June 2000 / Accepted: 29 June 2000 相似文献
16.
Chechetkin IR Osipova EV Antsygina LL Gogolev YV Grechkin AN 《Chemistry and physics of lipids》2011,(3):216-220
Lipoxygenases (LOXs) are key enzymes in the biosynthesis of oxylipins, the diverse class of bioregulators involved into developmental processes, signalling and defence. This work was undertaken to better understand how LOXs control production of hydroperoxides with different positional and stereochemistry. A number of glycerolipids were tested as substrates for maize 9-LOX (ZmLOX) and its A562G mutant form. Both the wild type (WT) ZmLOX and A562G mutant were shown to dioxygenate monolinolenoylglycerol (MLG) and 2-linoleoyl-sn-glycero-3-phosphorylcholine (lysoPC). Both the WT ZmLOX and A562G mutant form oxidized the MLG predominantly into (9S)-hydroperoxide. The A562G mutation did not affect the relative yield of 13-hydroperoxide, but increased the proportion of (13R)-enantiomer. LysoPC was a poor substrate for both wild type and A562G mutant form of ZmLOX. The oxidation of lysoPC exhibited the limited regio- and stereospecificity. Nevertheless, the WT ZmLOX produced some predominance of (13S)-hydroperoxide. In contrast, the A562G mutant produced some excess of (9S)-hydroperoxide of lysoPC. The bulky polar heads of glycerolipids like MLG and lysoPC cannot penetrate into the LOX active site. Thus, the obtained data indicate that both (9S)- and (13S)-hydroperoxides can be produced when substrate is arranged within LOX active site in the “methyl end first” orientation. 相似文献
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B. Djian E. Hornung T. Ischebeck I. Feussner 《Plant biology (Stuttgart, Germany)》2019,21(Z1):131-142
- The green microalga Lobosphaera incisa is an oleaginous eukaryotic alga that is rich in arachidonic acid (20:4). Being rich in this polyunsaturated fatty acid (PUFA), however, makes it sensitive to oxidation. In plants, lipoxygenases (LOXs) are the major enzymes that oxidise these molecules.
- Here, we describe, to our best knowledge, the first characterisation of a cDNA encoding a LOX (LiLOX) from a green alga. To obtain first insights into its function, we expressed it in E. coli, purified the recombinant enzyme and analysed its enzyme activity.
- The protein sequence suggests that LiLOX and plastidic LOXs from bryophytes and flowering plants may share a common ancestor. The fact that LiLOX oxidises all PUFAs tested with a consistent oxidation on the carbon n‐6, suggests that PUFAs enter the substrate channel through their methyl group first (tail first). Additionally, LiLOX form the fatty acid hydroperoxide in strict S configuration.
- LiLOX may represent a good model to study plastid LOX, because it is stable after heterologous expression in E. coli and highly active in vitro. Moreover, as the first characterised LOX from green microalgae, it opens the possibility to study endogenous LOX pathways in these organisms.
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Moataz M. Tawfik Katsuyuki T. Yamato Takayuki Kohchi Takao Koeduka 《Bioscience, biotechnology, and biochemistry》2017,81(6):1148-1155
Most terrestrial plants form green leaf volatiles (GLVs), which are mainly composed of six-carbon (C6) compounds. In our effort to study the distribution of the ability of lipoxygenase (LOX) to form GLVs, we found that a liverwort, Marchantia polymorpha, formed n-hexanal and (Z)-3-hexenal. Some LOXs execute a secondary reaction to form short chain volatiles. One of the LOXs from M. polymorpha (MpLOX7) oxygenized arachidonic and α-linolenic acids at almost equivalent efficiency and formed C6-aldehydes during its catalysis; these are likely formed from hydroperoxides of arachidonic and α-linolenic acids, with a cleavage of the bond between carbon at the base of the hydroperoxy group and carbon of double bond, which is energetically unfavorable. These lines of evidence suggest that one of the LOXs in liverwort employs an unprecedented reaction to form C6 aldehydes as by-products of its reaction with fatty acid substrates. 相似文献
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Regulation of methanol utilisation pathway genes in yeasts 总被引:1,自引:0,他引:1