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1.
Cytochrome P450 monooxygenases (P450s) metabolize herbicides to produce mainly non-phytotoxic metabolites. Although rice plants endogenously express multiple P450 enzymes, transgenic plants expressing other P450 isoforms might show improved herbicide resistance or reduce herbicide residues. Mammalian P450s metabolizing xenobiotics are reported to show a broad and overlapping substrate specificity towards lipophilic foreign chemicals, including herbicides. These P450s are ideal for enhancing xenobiotic metabolism in plants. A human P450, CYP1A1, metabolizes various herbicides with different structures and modes of herbicide action. We introduced human CYP1A1 into rice plants, and the transgenic rice plants showed broad cross-resistance towards various herbicides and metabolized them. The introduced CYP1A1 enhanced the metabolism of chlorotoluron and norflurazon. The herbicides were metabolized more rapidly in the transgenic rice plants than in non-transgenic controls. Transgenic rice plants expressing P450 might be useful for reducing concentrations of various chemicals in the environment.  相似文献   

2.
Phytoremediation is the use of plants to remove xenobiotic compounds from the environment. Plants have the inherent ability to detoxify xenobiotic pollutants, but they are generally poor at degrading them. The introduction of genes involved in xenobiotic degradation is aimed at enhancing plants' potential further. Rice (Oryza sativa) is a good candidate for this purpose and has been transformed with genes encoding cytochrome P450 monooxygenases CYP1A1, CYP2B6, and CYP2C19. The transgenic plants were more tolerant to various herbicides than nontransgenic Nipponbare rice plants, owing to enhanced metabolism by the introduced P450 enzymes. Transgenic plants were able to remove atrazine and metolachlor from soil. Field testing and risk assessment are very important for developing transgenic plants for phytoremediation. Transgenic rice plants should become useful as herbicide-tolerant crops and for phytoremediation of xenobiotic pollutants in future.  相似文献   

3.
Cytochrome monooxygenase P450s (CYPs) comprise one of the largest enzyme families in plants. Some P450s are involved in xenobiotic metabolism: they confer herbicide tolerance and are induced by chemical treatments. We isolated a novel P450 cDNA, CYP72A21 (accession number, AB237166), from rice (Oryza sativa L. cv. Nipponbare) seedlings treated with a mixture of 2,4-dichlorophenoxyacetic acid (2,4-D), chlorotoluron, phenobarbital, salicylic acid, and naphthalic anhydride (each 100 μM). We also isolated the gene’s promoter region. Endogenous CYP72A21 expression in rice seedlings treated with 2,4-D, herbicides esprocarb, or trifluralin was increased in the aerial part of seedlings. An expression plasmid, pI21pg, containing the GUS gene under the control of the CYP72A21 promoter was introduced into rice plants. GUS was expressed constitutively in roots, but this expression was suppressed by 2,4-D treatment. 2,4-D and other auxins induced GUS expression effectively in the stem and leaves. Histological observation revealed that GUS was expressed mainly in the base of the stem. Treatment with the herbicides acetochlor, esprocarb, and propyzamide induced GUS expression in the aerial parts of the seedlings. The CYP72A21 promoter was highly responsive to treatments with various chemicals, and thus might be useful for producing transgenic plants for biomonitoring of environmental chemicals.  相似文献   

4.
A gene of the enzyme involved in xenobiotic metabolism in mammalian liver was introduced into potato to confer inducible herbicide tolerance. A rat cytochrome P450 monooxygenase, CYP1A1 cDNA, was kept under the control of the tobacco PR1a promoter in order to apply the system of chemical inducible expression using the plant activator Benzothiadiazole (BTH). Transgenic plants were obtained based on the kanamycin resistance test and PCR analysis. Northern-blot analysis revealed the accumulation of mRNA corresponding to rat CYP1A1 in the transgenic plants treated with BTH (3.0 μmol/pot), whereas no accumulation of the corresponding mRNA occurred without BTH treatment. These transgenic plants also produced a protein corresponding to CYP1A1 in the leaves by BTH treatment. The transgenic plants with BTH application showed a much-higher tolerance to the phenylurea herbicides chlortoluron and methabenzthiazuron than non-transgenic plants. These findings indicated that the ability of metabolizing the two herbicides to less-toxic derivatives was displayed in the transgenic plants after BTH treatment. Transgenic plants harboring the CYP1A1 cDNA fused with the yeast P450 reductase (YR) gene under the control of PR1a were also produced. Although the plants showed a lower expression level of the fused gene than transgenic plants with CYP1A1 cDNA alone, they were tolerant to herbicides. These facts suggested that the CYP1A1 enzyme fused with YR showed a higher specific activity than CYP1A1 alone. This study demonstrated that the mammalian cDNA for the de-toxification enzyme of herbicides under the control of the PR1a promoter conferred chemical-inducible herbicide tolerance on potato. Received: 15 March 2001 / Accepted: 14 June 2001  相似文献   

5.
Bentazon and sulfonylurea are two different classes of herbicides that have been widely used to kill broad-leaf weeds in rice fields. A cytochrome P450 gene, CYP81A6, encoding a monooxygenase has been previously identified to confer resistance to these two classes of herbicides in wild-type rice. In this study, we introduced the rice CYP81A6 gene into Arabidopsis and tobacco plants to test the possibility of engineering tolerance to these two types of herbicides in other susceptible plants. Arabidopsis and tobacco plants expressing CYP81A6 showed tolerance to both bentazon and bensulfuron-methyl (BSM), a widely applied sulfonylurea herbicide. The optimal concentrations of bentazon and BSM for the selection of CYP81A6 transgenic plants were also determined. In addition, we also demonstrated that CYP81A6 can be used as a selection marker to effectively screen for positive transgenic Arabidopsis plants. The selection efficiency of CYP81A6 was comparable to that of the bar gene in Arabidopsis. These results suggest that CYP81A6 can not only be used to produce transgenic plants tolerant to both bentazon and sulfonylureas, but that it can also be used as a novel plant-derived selection marker in plant transformation.  相似文献   

6.
Among 11 isoforms of the human cytochrome P450 enzymes metabolizing xenobiotics, CYP 1A1 and CYP 1A2 were major P450 species in the metabolism of the herbicides chlortoluron and atrazine in a yeast expression system. CYP1A2 was more active in the metabolism of both herbicides than CYP1A1. The fused enzymes of CYP1A1 and CYP1A2 with yeast NADPH-cytochrome P450 oxidoreductase were functionally active in the microsomal fraction of the yeast Saccharomyces cerevisiae and showed increased specific activity towards 7-ethoxyresorufin as compared to CYP1A1 and CYP1A2 alone. Then, both fused enzymes were each expressed in the microsomes of tobacco (Nicotiana tabacum cv. Samsun NN) plants. The transgenic plants expressing the CYP1A2 fusion enzyme had higher resistance to the herbicide chlortoluron than the plants expressing the CYP1A1 fusion enzyme did. The transgenic plants expressing the CYP1A2 fused enzyme metabolized chlortoluron to a larger extent to its non-phytotoxic metabolites through N-demethylation and ring-methyl hydroxylation as compared to the plants expressing the CYP1A1 fused enzyme. Thus, the possibility of increasing the herbicide resistance in the transgenic plants by the selection of P450 species and the fusion with P450 reductase is discussed.  相似文献   

7.
The potential use of human P450-transgenic plants for phytoremediation of pesticide contaminated soils was tested in laboratory and greenhouse experiments. The transgenic P450 CYP1A2 gene Arabidopsis thaliana plants metabolize number of herbicides, insecticides and industrial chemicals. The P450 isozymes CYP1A2 expressed in A. thaliana were examined regarding the herbicide simazine (SIM). Transgenic A. thaliana plants expressing CYP1A2 gene showed significant resistance to SIM supplemented either in plant growth medium or sprayed on foliar parts. The results showed that SIM produces harmful effect on both rosette diameter and primary root length of the wild type (WT) plants. In transgenic A. thaliana lines, the rosette diameter and primary root length were not affected by SIM concentrations used in this experiment. The results indicate that CYP1A2 can be used as a selectable marker for plant transformation, allowing efficient selection of transgenic lines in growth medium and/or in soil-grown plants. The transgenic A. thaliana plants exhibited a healthy growth using doses of up to 250 μmol SIM treatments, while the non-transgenic A. thaliana plants were severely damaged with doses above 50 μmol SIM treatments. The transgenic A. thaliana plants can be used as phytoremediator of environmental SIM contaminants.  相似文献   

8.
The final reactions of rosmarinic acid biosynthesis, the introduction of the aromatic 3- and 3′-hydroxyl groups, are catalysed by cytochrome P450-dependent hydroxylases. The cDNAs encoding CYP98A14 as well as a NADPH:cytochrome P450 reductase (CPR) were isolated from Coleus blumei and actively expressed in Saccharomyces cerevisiae. The CYP98A14-cDNA showed an open reading frame of 1521 nucleotides with high similarities to 4-coumaroylshikimate/quinate 3-hydroxylases. Yeast microsomes harbouring the CYP98A14 protein catalysed the 3-hydroxylation of 4-coumaroyl-3′,4′-dihydroxyphenyllactate and the 3′-hydroxylation of caffeoyl-4′-hydroxyphenyllactate, in both cases forming rosmarinic acid. Apparent K m-values for 4-coumaroyl-3′,4′-dihydroxyphenyllactate and caffeoyl-4′-hydroxyphenyllactate were determined to be at 5 μM and 40 μM, respectively. CYP98A14 differs from CYP98s from other plants, since 4-coumaroylshikimate or -quinate were not accepted as substrates. Coexpression of the Coleus blumei CPR and CYP98A14 in the same yeast cells increased the hydroxylation activity up to sevenfold. CYP98A14 from Coleus blumei is a novel bifunctional cytochrome P450 specialised for rosmarinic acid biosynthesis.  相似文献   

9.
A rat P450 monooxygenase gene (CYP1A1) was introduced into potato plants to enhance the metabolism of the environmental contaminants in subterranean organs. The CYP1A1 gene was kept under the control of the potato patatin promoter to enhance tuber-specific expression. A total of 106 transgenic plants (PAT1A1 plants) were obtained following selection by a resistance test to kanamycin and PCR analysis. PAT1A1 plants treated with 10% exogenous sucrose showed a higher activity of monooxgenase in the leaves than the non-transgenic plants. This indicated that the activity enhanced by 10% sucrose was due to the patatin promoter containing the sucrose-inducted elements. One representative transgenic plant, Ag2197, was selected on the basis of monooxgenase activity in the leaves and Western blot analysis. Ag2197 was found to accumulate a large amount of CYP1A1 mRNA and protein in the developing tuber but not in the mature tuber. The residual herbicides, atrazine and chlortoluron, were analyzed in the micro-tubers of Ag2197 and non-transgenic plants. The amount of residual herbicides in Ag2197 was much lower than that in the non-transgenic plant, indicating that the transgenic plant metabolized the herbicides to a detoxified form. The transgenic plants produced in this study might be useful for the phytoremediation of chemical pollution in the soil.  相似文献   

10.
The Jerusalem artichoke (Helianthus tuberosus) xenobiotic inducible cytochrome P450, CYP76B1, catalyzes rapid oxidative dealkylation of various phenylurea herbicides to yield nonphytotoxic metabolites. We have found that increased herbicide metabolism and tolerance can be achieved by ectopic constitutive expression of CYP76B1 in tobacco (Nicotiana tabacum) and Arabidopsis. Transformation with CYP76B1 conferred on tobacco and Arabidopsis a 20-fold increase in tolerance to linuron, a compound detoxified by a single dealkylation, and a 10-fold increase in tolerance to isoproturon or chlortoluron, which need successive catalytic steps for detoxification. Two constructs for expression of translational fusions of CYP76B1 with P450 reductase were prepared to test if they would yield even greater herbicide tolerance. Plants expressing these constructs had lower herbicide tolerance than CYP76B1 alone, which is apparently a consequence of reduced stability of the fusion proteins. In all cases, increased herbicide tolerance results from more extensive metabolism, as demonstrated with exogenously fed phenylurea. Beside increased herbicide tolerance, expression of CYP76B1 has no other visible phenotype in the transgenic plants. Our data indicate that CYP76B1 can function as a selectable marker for plant transformation, allowing efficient selection in vitro and in soil-grown plants. Plants expressing CYP76B1 may also be a potential tool for phytoremediation of contaminated sites.  相似文献   

11.
We have characterized cytochromes P450, CYP710A13, and CYP710A14, as the sterol C22-desaturase in the moss Physcomitrella patens. GC–MS analyses demonstrated that P. patens accumulated stigmasterol as the major sterol (56–60% of total sterol) and sitosterol to a lesser extent (8–12%); this sterol profile contrasts with those in higher plants accumulating stigmasterol as a minor component. Recombinant CYP710A13 and CYP710A14 proteins prepared using a baculovirus/insect cell system exhibited the C22-desaturase activity with β-sitosterol to produce stigmasterol, while campesterol and 24-epi-campesterol were not accepted as the substrates. The K m values for β-sitosterol of CYP710A13 (1.0 ± 0.043 μM) and CYP710A14 (2.1 ± 0.17 μM) were at comparable levels of those reported with higher plant CYP710A proteins. In Arabidopsis T87 cells over-expressing CYP710A14, stigmasterol contents reached a level 20- to 72-fold higher than those in the basal level of T87 cells, confirming the C22-desaturase activity of this P450 enzyme. The occurrence of the end-products together with the enzymes involved in the last step of the pathway substantiated the presence of an entire sterol biosynthetic pathway in P. patens, providing evidence for the conservation of the sterol biosynthetic pathway through the evolutionary process of land plants. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

12.
13.
Rapid and widespread evolution of multiple herbicide resistance in global weed species endowed by increased capacity to metabolize (degrade) herbicides (metabolic resistance) is a great threat to herbicide sustainability and global food production. Metabolic resistance in the economically damaging crop weed species Lolium rigidum is well known but a molecular understanding has been lacking. We purified a metabolic resistant (R) subset from a field evolved R L. rigidum population. The R, the herbicide susceptible (S) and derived F2 populations were used for candidate herbicide resistance gene discovery by RNA sequencing. A P450 gene CYP81A10v7 was identified with higher expression in R vs. S plants. Transgenic rice overexpressing this Lolium CYP81A10v7 gene became highly resistant to acetyl-coenzyme A carboxylase- and acetolactate synthase-inhibiting herbicides (diclofop-methyl, tralkoxydim, chlorsulfuron) and moderately resistant to hydroxyphenylpyruvate dioxygenase-inhibiting herbicide (mesotrione), photosystem II-inhibiting herbicides (atrazine and chlorotoluron) and the tubulin-inhibiting herbicide trifluralin. This wide cross-resistance profile to many dissimilar herbicides in CYP81A10v7 transgenic rice generally reflects what is evident in the R L. rigidum. This report clearly showed that a single P450 gene in a cross-pollinated weed species L. rigidum confers resistance to herbicides of at least five modes of action across seven herbicide chemistries.  相似文献   

14.
Quantitative structure-activity relationships (QSARs) within a series of cytochrome P450 2C9 (CYP2C9) and cytochrome P450 2C19 (CYP2C19) inhibitors are reported. In particular, it is noted that compound lipophilicity, in the form of log P values (where P is the octanol/water partition coefficient), is an important factor in explaining the variation in inhibitory potency within these series of compounds, many of which also act as substrates for the respective enzymes. In addition, there is a role for hydrogen bonding and π-π stacking interactions within the P450 active site which represent secondary factors in the binding processes of these compounds.  相似文献   

15.
CYP119, the first thermophilic P450 enzyme, reacts much more slowly than CYP101 (P450cam) with aryldiazenes to give σ-bonded aryl-iron complexes. The CYP119 complexes are stable anaerobically at 80 °C but are readily oxidized by O2 to give the N-arylprotoporphyrin IX regioisomers. The aryl shift can also be initiated in the absence of O2 by K3Fe(CN)6. In contrast, the corresponding CYP101 complexes are insensitive to O2 but decompose at temperatures above 50 °C owing to denaturation of the protein. The rate of the CYP119 aryl shift is decreased by electron-withdrawing substituents, with ρ=−1.50 for both the O2- and K3Fe(CN)6-dependent reactions. A similar dependence (ρ=−0.90) is observed for the K3Fe(CN)6-dependent CYP101 shift. The enthalpies and entropies of activation suggest that the CYP119 and CYP101 K3Fe(CN)6-mediated reactions are similar, but the CYP119 O2-dependent reaction proceeds via a different transition state. In all cases, the rate-determining step is oxidation of the aryl-iron complex. The temperature dependence of the O2- and K3Fe(CN)6-dependent CYP119 shifts provides evidence for temperature-dependent equilibration of two active site conformations. The oxygen sensitivity of the CYP119 aryl-iron complexes, and the temperature dependence of their rearragement, reflect the unique active site properties of this thermophilic P450 enzyme. Received: 12 August 1999 / Accepted: 8 December 1999  相似文献   

16.
Salinity stress is a major limiting factor in cereal productivity. Many studies report improvements in salt tolerance using model plants, such as Arabidopsis thaliana or standard varieties of rice, e.g., the japonica rice cultivar Nipponbare. However, there are few reports on the enhancement of salt tolerance in local rice cultivars. In this work, we used the indica rice (Oryza sativa) cultivar BR5, which is a local cultivar in Bangladesh. To improve salt tolerance in BR5, we introduced the Escherichia coli catalase gene, katE. We integrated the katE gene into BR5 plants using an Agrobacterium tumefaciens-mediated method. The introduced katE gene was actively expressed in the transgenic BR5 rice plants, and catalase activity in T1 and T2 transgenic rice was approximately 150% higher than in nontransgenic plants. Under NaCl stress conditions, the transgenic rice plants exhibited high tolerance compared with nontransgenic rice plants. T2 transgenic plants survived in a 200 mM NaCl solution for 2 weeks, whereas nontransgenic plants were scorched after 4 days soaking in the same NaCl solution. Our results indicate that the katE gene can confer salt tolerance to BR5 rice plants. Enhancement of salt tolerance in a local rice cultivar, such as BR5, will provide a powerful and useful tool for overcoming food shortage problems.  相似文献   

17.
The arachidonic acid metabolizing CYP enzymes with prominent roles in vascular regulation are epoxygenases of the two gene family which generate epoxyeicosatrienoic acids. Carriers of CYP2C9 mutant alleles exhibit a diminished CYP2C9 metabolic capacity leading to decreased endothelium-derived hyperpolarizing factors (EDHF) synthesis and an increased risk for atherosclerosis. We investigated whether the polymorphisms of CYP2C9/19 are related with atherosclerosis. We examined 108 patients having angioraphically > or =70 coronary artery narrowing and 90 healthy controls. CYPC2C9/19*2 and CYP2C9/19*3 alleles were investigated in both patients and controls by a real time PCR instrument. There was no significant difference in the distribution of the CYP2C9*2/*3 alleles between cases and the controls. We found that smoker patients having CYP2C9*2 heterozygote genotype have 3.7-fold risk of developing atherosclerosis. CYP2C19*3 heterozygote alleles are more frequent in patients than in controls (10.2%, 5.6% respectively) and it is related with a three-fold risk of atherosclerosis (odds ratio (OR) = 3.75, confidence interval (CI) = 0.75-18.65). It becomes clear that cigarette smoking can cause almost all major diseases prevalent today, such as cancer or heart disease. This inter-subject variability in cigarette-induced pathologies is partly mediated by genetic variants of genes that may participate in detoxification processes, e.g., cytochrome P450 (CYP), cellular susceptibility to toxins, such as p53, or disease development such as atherosclerosis.  相似文献   

18.
Genes conferring resistance to the herbicides glyphosate, oxyfluorfen and norflurazon were developed and tested for use as dominant selectable markers in genetic transformation of Chlamydomonas reinhardtii and as potential tools for the protection of commercial‐scale algal production facilities against contamination by organisms sensitive to these broad‐spectrum herbicides. A synthetic glyphosate acetyltransferase (GAT) gene, when fitted with a strong Chlamydomonas promoter, conferred a 2.7×‐fold increase in tolerance to the EPSPS inhibitor, glyphosate, in transgenic cells compared with progenitor WT cells. A mutant Chlamydomonas protoporphyrinogen oxidase (protox, PPO) gene previously shown to produce an enzyme insensitive to PPO‐inhibiting herbicides, when genetically engineered, generated transgenic cells able to tolerate up to 136× higher levels of the PPO inhibitor, oxyfluorfen, than nontransformed cells. Genetic modification of the Chlamydomonas phytoene desaturase (PDS) gene‐based gene sequences found in various norflurazon‐resistant organisms allowed production of transgenic cells tolerant to 40× higher levels of norflurazon than nontransgenic cells. The high efficiency of all three herbicide resistance genes in producing transgenic cells demonstrated their suitability as dominant selectable markers for genetic transformation of Chlamydomonas and, potentially, other eukaryotic algae. However, the requirement for high concentrations of glyphosate and its associated negative effects on cell growth rates preclude its consideration for use in large‐scale production facilities. In contrast, only low doses of norflurazon and oxyfluorfen (~1.5 μm and ~0.1 μm , respectively) are required for inhibition of cell growth, suggesting that these two herbicides may prove effective in large‐scale algal production facilities in suppressing growth of organisms sensitive to these herbicides.  相似文献   

19.
In the mitochondria of animal steroidogenic tissues, cytochrome P450SCC encoded by the CYP11A1 gene catalyzes the conversion of cholesterol into pregnenolone—the general precursor of all steroid hormones. In this work we study the steroid metabolism in transgenic tobacco plants carrying the CYP11A1 cDNA encoding cytochrome P450SCC from the bovine adrenal cortex. The transgenic plants under investigation markedly surpass the control wild-type plants by size and are characterized by a shortened period of vegetative growth (by rapid flowering); their leaves contain pregnenolone—the product of a reaction catalyzed by cytochrome P450SCC. The level of progesterone in transgenic tobacco leaves is higher than in the control plants of the wild type. The seeds of the transgenic plants contain less (24R)-brassinosteroids than the wild-type tobacco plants. The results obtained indicate that the synthesis of an active P450SCC cytochrome in transgenic Nicotiana tabacum plants has a profound effect on steroid metabolism and is responsible for the specific phenotypic features of transgenic plants bearing CYP11A1 cDNA.  相似文献   

20.
杨娇艳  廖明军  杨劭 《生物工程学报》2008,24(10):1681-1688
甾醇14α-去甲基化酶(CYP51)是分布最广的细胞色素P450家族成员,是生物甾醇合成过程中的关键酶.故CYP51不仅是细胞色素P450蛋白结构、功能、结构与功能关系等研究的模板,而且是重要的降胆固醇药物、抗真菌药物和除草剂作用靶标,具有重要的经济价值.以下就CYP51家族的序列特征、功能(生理功能和生化特征)、结构、结构与功能的关系、CYP51活性的抑制等方面的研究进展进行了综述.并对CYP51抑制剂的研究局限方面进行了讨论,探讨了CYP51抑制剂设计开发的相关问题.  相似文献   

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