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1.
Balashova NV Stolz A Knackmuss HJ Kosheleva IA Naumov AV Boronin AM 《Biodegradation》2001,12(3):179-188
1-Hydroxy-2-naphthoate is formed as an intermediate in the bacterial degradation of phenanthrene. A monooxygenase which catalyzed the oxidation of 1-hydroxy-2-naphthoateto 1,2-dihydroxynaphthalene was purified from the phenanthrene- and naphthalene-degrading Pseudomonas putida strain BS202-P1. The purified protein had a molecular weight of45 kDa and required NAD(P)H and FAD as cofactors. The purified enzyme also catalysed the oxidation of salicylate and various substituted salicylates. The comparison of the Kmand Vmax values for 1-hydroxy-2-naphthoate and salicylate demonstrated a higher catalytic efficiency of the enzyme for salicylate as a substrate. A significant substrate-inhibition was detected with higher concentrations of 1-hydroxy-2-naphthoate.The aminoterminal amino acid sequence of the purified enzyme showed significant homologies to salicylate 1-monooxygenases from other Gram negative bacteria. It was therefore concluded that during the degradation of phenanthrene the conversion of 1-hydroxy-2-naphthoate to 1,2-dihydroxynaphthalene is catalysed by a salicylate1-monooxygenase. Together with previous studies, this suggested that the enzymes of the naphthalene pathway are sufficient to catalyse also the mineralization of phenanthrene. 相似文献
2.
Prashant S. Phale Milind C. Mahajan Chelakard S. Vaidyanathan 《Archives of microbiology》1995,163(1):42-47
Pseudomonas maltophilia CSV89, a bacterium isolated from soil in our laboratory, grows on 1-naphthoic acid as the sole source of carbon and energy. To elucidate the pathway for degradation of 1-naphthoic acid, the metabolites were isolated from spent medium, purified by TLC, and characterized by gas chromatography-mass spectrometry. The involvement of various metabolites as intermediates in the pathway was established by demonstrating relevant enzyme activities in cell-free extracts, oxygen uptake and transformation of metabolites by the whole cells. The results obtained from such studies suggest that the degradation of 1-naphthoic acid is initiated by double hydroxylation of the aromatic ring adjacent to the one bearing the carboxyl group, resulting in the formation of 1,2-dihydroxy-8-carboxynaphthalene. The resultant diol was oxidized via 3-formyl salicylate, 2-hydroxyisophthalate, salicylate and catechol to TCA cycle intermediates. 相似文献
3.
Benoit Guieysse Xavier Borde Raul Muñoz Rajni Hatti-Kaul Caroline Nugier-Chauvin Henri Patin Bo Mattiasson 《Biotechnology letters》2002,24(7):531-538
The influence of the initial composition of an algal-bacterial microcosm constituted of Chlorella sorokiniana and Ralstonia basilensis was tested for the fed-batch degradation of salicylate at 5 mM. Salicylate degradation was always limited by the O2 generation rate, which was initially proportional to the algal density, but rapidly became limited by the availability of light once the algae started to grow. The decrease of the salicylate removal rate observed at high algal densities was likely caused by mutual shading within the algal population and the increase of O2 consumption due to algal dark respiration. With repeated salicylate amendments, all systems converged towards the same characteristics, reaching an optimum rate of salicylate degradation at 1 mmol l–1 day. 相似文献
4.
2,3-Dihydroxybenzoic acid decarboxylase inAspergillus niger was induced by many substrate analogs including salicylate and gentisate. Catechol, which is the product, induced the enzyme tenfold. The purified enzyme was competitively inhibited by manyortho substituted benzoic acids. The Ki values for salicylate,o-fluoro ando-chloro benzoic acids were 0.12 mM, 0.12 mM, and 0.13 mM respectively; these values were lower than the Km value for the substrate. As the size of the group in theortho position increased, as in the case of bromo- and iodo-derivatives, there was an increase in their Ki values. The C-2 hydroxyl group was essential both for the induction and for interaction with the enzyme. The C-3 hydroxyl group was not necessary for induction or inhibition, but it might be essential for the catalysis. 相似文献
5.
Kosheleva I. A. Balashova N. V. Izmalkova T. Yu. Filonov A. E. Sokolov S. L. Slepen'kin A. V. Boronin A. M. 《Microbiology》2000,69(6):663-669
Five naphthalene- and salicylate-utilizing Pseudomonas putida strains cultivated for a long time on phenanthrene produced mutants capable of growing on this substrate and 1-hydroxy-2-naphthoate as the sole sources of carbon and energy. The mutants catabolize phenanthrene with the formation of 1-hydroxy-2-naphthoate, 2-hydroxy-1-naphthoate, salicylate, and catechol. The latter products are further metabolized by the meta- and ortho-cleavage pathways. In all five mutants, naphthalene and phenanthrene are utilized with the involvement of plasmid-born genes. The acquired ability of naphthalene-degrading strains to grow on phenanthrene is explained by the fact that the inducible character of the synthesis of naphthalene dioxygenase, the key enzyme of naphthalene and phenanthrene degradation, becomes constitutive. 相似文献
6.
Characterization of tobacco plants expressing a bacterial salicylate hydroxylase gene 总被引:10,自引:0,他引:10
Leslie Friedrich Bernard Vernooij Tom Gaffney Alison Morse John Ryals 《Plant molecular biology》1995,29(5):959-968
Transgenic tobacco plants that express the bacterial nahG gene encoding salicylate hydroxylase have been shown to accumulate very little salicylic acid and to be defective in their ability to induce systemic acquired resistance (SAR). In recent experiments using transgenic NahG tobacco and Arabidopsis plants, we have also demonstrated that salicylic acid plays a central role in both disease susceptibility and genetic resistance. In this paper, we further characterize tobacco plants that express the salicylate hydroxylase enzyme. We show that tobacco mosaic virus (TMV) inoculation of NahG tobacco leaves induces the accumulation of the nahG mRNA in the pathogen infected leaves, presumably due to enhanced stabilization of the bacterial mRNA. SAR-associated genes are expressed in the TMV-infected leaves, but this is localized to the area surrounding necrotic lesions. Localized acquired resistance (LAR) is not induced in the TMV-inoculated NahG plants suggesting that LAR, like SAR, is dependent on SA accumulation. When SA is applied to nahG-expressing leave's SAR gene expression does not result. We have confirmed earlier reports that the salicylate hydroxylase enzyme has a narrow substrate specificity and we find that catechol, the breakdown product of salicylic acid, neither induces acquired resistance nor prevents the SA-dependent induction of the SAR genes. 相似文献
7.
S. Harayama M. Rekik A. Wasserfallen A. Bairoch 《Molecular & general genetics : MGG》1987,210(2):241-247
Summary TOL plasmid pWW0 and plasmid NAH7 encode catabolic enzymes required for oxidative degradation of toluene and naphthalene, respectively. The gene order of the catabolic operon of NAH7 for salicylate oxidation was determined to be: promoter-nahG (the structural gene for salicylate hydroxylase)-nahH (catechol 2,3-dioxygenase)-nahI (hydroxymuconic semialdehyde dehydrogenase)-nahN (hydroxymuconic semialdehyde hydrolase)-nahL (2-oxopent-4-enoate hydratase). This order is identical to that of the isofunctional genes of TOL plasmid pWW0. The complete nucleotide sequence of nahH was determined and compared with that of xylE, the isofunctional gene of TOL plasmid pWW0. There were 20% and 16% differences in their nucleotide and amino acid sequences, respectively. The homology between the NAH7 and TOL pWW0 plasmids ends upstream of the Shine-Dalgarno sequences of nahH and xylE, but the homology continues downstream of these genes. This observation suggested that genes for the catechol oxidative enzymes of NAH7 and TOL pWW0 were derived from a common ancestral sequence which was transferred as a discrete segment of DNA between plasmids. 相似文献
8.
Wei?E.?Huang Royston?Goodacre Geoff?N.?Elliott Manfred?Beckmann Hilary?Worgan Mark?J.?Bailey Peter?A.?Williams John?Scullion John?Draper
This study explores the utility of Fourier transform infra-red spectroscopy (FT-IR) as a metabolomic tool to detect changes in water-extractable chemical profile resulting from horizontal gene transfer (HGT) events in artificial soil slurries. A GFP–Km (Green fluorescent protein–kanamycin) cassette tagged HGT recipient Acinetobacter strain ADPWH67 with the salicylate hydroxylase gene (salA) disrupted was introduced to slurries containing either sterile or non-sterile soil. The subsequent addition of naked salA DNA allowed the specific monitoring of HGT events by enumerating GFP-expressing colonies on minimal media with salicylate as a sole carbon source. DNA sequencing confirmed that salA was restored in these transformants. Gene transformation frequencies of around 10−6 were achieved in the presence of sterile and non-sterile soils. Aqueous extracts of the soil slurries were then analyzed using FT-IR in order to ascertain whether any shifts in chemical profile could be detected. We found that following HGT events FT-IR chemical profiles were clearly altered when analyzed with multivariate statistics. Furthermore, these changes could be explained by differences in key chemical signatures including salicylate as well as other biomolecules found in soils. The slurry extracts were also subjected to GC-MS which confirmed the results of FT-IR analyses. FT-IR was therefore demonstrated to have utility for the rapid screening of metabolomic changes in soils following effective HGT events. In addition, this approach could potentially link specific metabolite changes with corresponding catabolic genes.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
9.
Change in response of Rhopalosiphum padi spring migrants to the repellent winter host component methyl salicylate 总被引:2,自引:0,他引:2
Olfactometry showed that the response of spring migrants of the bird cherry-oat aphid, Rhopalosiphum padi (L.) (Homoptera: Aphididae), to the repellent winter host volatile methyl salicylate changes with age of the adult aphid. Between three and four days after becoming adult, and having left the winter host Prunus padus L., aphids lost their negative response to the chemical. The change in response was not associated with contact with a summer host, oats. In a settling choice bioassay, migrants avoided oats which had been exposed to volatile methyl salicylate. Aphids with removed antennal tips did not avoid the exposed plant, indicating that plant choice was influenced by cues from the plant surface. The results are discussed in relation to the use of methyl salicylate in integrated control. 相似文献
10.
Functional analysis of a tomato salicylic acid methyl transferase and its role in synthesis of the flavor volatile methyl salicylate 总被引:1,自引:0,他引:1
Denise Tieman Michelle Zeigler Eric Schmelz Mark G. Taylor Sarah Rushing Jeffrey B. Jones Harry J. Klee 《The Plant journal : for cell and molecular biology》2010,62(1):113-123
Methyl salicylate (MeSA) is a volatile plant secondary metabolite that is an important contributor to taste and scent of many fruits and flowers. It is synthesized from salicylic acid (SA), a phytohormone that contributes to plant pathogen defense. MeSA is synthesized by members of a family of O‐methyltransferases. In order to elaborate the mechanism of MeSA synthesis in tomato, we screened a set of O‐methyltransferases for activity against multiple substrates. An enzyme that specifically catalyzes methylation of SA, SlSAMT, as well as enzymes that act upon jasmonic acid and indole‐3‐acetic acid were identified. Analyses of transgenic over‐ and under‐producing lines validated the function of SlSAMT in vivo. The SlSAMT gene was mapped to a position near the bottom of chromosome 9. Analysis of MeSA emissions from an introgression population derived from a cross with Solanum pennellii revealed a quantitative trait locus (QTL) linked to higher fruit methyl salicylate emissions. The higher MeSA emissions associate with significantly higher SpSAMT expression, consistent with SAMT gene expression being rate limiting for ripening‐associated MeSA emissions. Transgenic plants that constitutively over‐produce MeSA exhibited only slightly delayed symptom development following infection with the disease‐causing bacterial pathogen, Xanthomonas campestris pv. vesicatoria (Xcv). Unexpectedly, pathogen‐challenged leaves accumulated significantly higher levels of SA as well as glycosylated forms of SA and MeSA, indicating a disruption in control of the SA‐related metabolite pool. Taken together, the results indicate that SlSAMT is critical for methyl salicylate synthesis and methyl salicylate, in turn, likely has an important role in controlling SA synthesis. 相似文献
11.
Ibrahim M. Banat Poonam Nigam Roger Marchant 《Applied microbiology and biotechnology》1992,37(3):378-381
Summary A salicylate-hydroxylase-producing strain of Pseudomonas putida with an unusual capability to grow at toxic levels of salicylate up to 10 g l–1 has been isolated. It grew well under continuous culture conditions, with optimum growth at pH 6.5 and a temperature of 25° C. The use of an ammonium salt as a nitrogen source, instead of nitrate, resulted in a 30–40% increase in its biomass yield coefficient. Optimum growth under continuous culture conditions was achieved using 4 g l–1 salicylate at 25° C, pH 6.5 and 0.2 h–1 dilution rate. High salicylate hydroxylase enzyme activity [236 units (U) l–1] and productivity (424.8 U h–1) were obtained at a dilution rate of 0.45 h–1 using a mineral medium containing 4 g l–1 of salicylate. Operating under continuous culture conditions with oxygen limitation and a slight accumulation of residual salicylate (0.2 g l–1) resulted in a decrease in culture performance and enzyme productivity.
Correspondence to: R. Marchant 相似文献
12.
Mordukhova E. A. Kochetkov V. V. Lobanova E. V. Slepen'kin A. V. Boronin A. M. 《Microbiology》2000,69(6):721-725
The effect of sodium salicylate on the population dynamics of the rhizobacterium Pseudomonas aureofaciens BS1393 and its variant bearing the naphthalene biodegradation plasmid pBS216 was studied in the wheat rhizoplane and adjacent soil. Optimum salicylate concentration for the maintenance of the plasmid-bearing strain and for the normal growth of wheat was found to be 250 g/g soil. When the soil was supplemented with salicylate, the population of P. aureofaciens BS1393(pBS216) in the wheat rhizoplane and adjacent soil was, respectively, 4- and 20-fold higher than that of the parent strain lacking the plasmid. 相似文献
13.
Yuta Miki María Morales Francisco J. Ruiz-Dueas María Jesús Martínez Hiroyuki Wariishi Angel T. Martínez 《Protein expression and purification》2009,68(2):208-214
Heterologous expression of Trametes cervina lignin peroxidase (LiP), the only basidiomycete peroxidase that has a catalytic tyrosine, was investigated. The mature LiP cDNA was cloned into the pET vector and used to transform Escherichia coli. Recombinant LiP protein accumulated in inclusion bodies as an inactive form. Refolding conditions for its in vitro activation—including incorporation of heme and structural Ca2+ ions, and formation of disulfide bridges—were optimized taking as a starting point those reported for other plant and fungal peroxidases. The absorption spectrum of the refolded enzyme was identical to that of wild LiP from T. cervina suggesting that it was properly folded. The enzyme was able to oxidize 1,4-dimethoxybenzene and ferrocytochrome c confirming its high redox potential and ability to oxidize large substrates. However, during oxidation of veratryl alcohol (VA), the physiological LiP substrate, an unexpected initial lag period was observed. Possible modification of the enzyme was investigated by incubating it with H2O2 and VA (for 30 min before dialysis). The pretreated enzyme showed normal kinetics traces for VA oxidation, without the initial lag previously observed. Steady-state kinetics of the pretreated LiP were almost the same as the recombinant enzyme before the pretreatment. Moreover, the catalytic constant (kcat) for VA oxidation was comparable to that of wild LiP from T. cervina, although the Michaelis–Menten constant (Km) was 8-fold higher. The present heterologous expression system provides a valuable tool to investigate structure–function relationships, and autocatalytic activation of the unique T. cervina LiP. 相似文献
14.
I. Francis Cheng Christopher P. Zhao Andris Amolins Malgorzata Galazka Leon Doneski 《Biometals》1996,9(3):285-290
This paper presents a new hypothesis for the physiological antioxidant action of salicylate. Current theories have focused on the radical scavenging nature of salicylate. This explanation may have limitations because it is unlikely that salicylate reaches the necessary concentrations to effectively prevent damage to cell components. We propose that salicylic acid decreases the flux of hydroxyl radicals through chelation, which causes a redox deactivation mechanism of iron Fenton reaction centers. This is due to voltammetric results which indicate that the iron-salicylate complex does not have the thermodynamic driving force to act as an effective Fenton reagent necessary for the production of damaging oxygen-containing radicals. Furthermore, despite the more facile thermodynamics associated with Fenton-type processes at acidic pH values, the complex maintains Fenton inactivity due to a pH-sensitive redox potential shift that follows asE
Fe[Sal] = 0.793 - (0.059 pH). This is important since inflammation sites are acidic relative to healthy tissue. This redox potential shift is unique to salicylates when compared with other common iron chelation agents such as EDTA. Further evidence for the lack of Fenton-type reactivity of the iron-salicylate complex is offered in the form of oxidation studies of calf thymus (CT) DNA by hydrogen peroxide. Salicylate prevents the iron-catalyzed oxidation of CT-DNA strands as indicated by the detection of the constituent bases by HPLC. However, salicylates were not able to prevent the copper-catalyzed oxidation of CT-DNA. These results are predicted by the cyclic voltammetry of copper-salicylate, which confirms that it is an effective Fenton-type catalyst, further adding to the proof that salicylate acts by redox deactivation of iron, not by hydroxyl radical scavenging. Finally, the iron-salicylate e.m.f. suggests that it may also act as a superoxide dismutase, which indicates another possible important antioxidant feature. 相似文献
15.
Thierry Maugard Melanie Boulonne Barbara Rejasse Marie Dominique Legoy 《Biotechnology letters》2001,23(12):989-993
A novel enzymatic method for preparing water-soluble derivatives of salicylic acid catalyzed by immobilized lipase was described. This study is the first to describe the enzymatic transesterification of methyl salicylate in organic solvents with different hydroxyl donors. The acyl-transfer between methyl salicylate and sorbitol was best supported by solvents of log P values –0.33 to 1.4. With Candida antarctica lipase in tert-amyl alcohol, a sorbitol conversion yield of 98% can be obtained by transesterification with sorbitol and methyl salicylate in one step. 相似文献
16.
Ergosterol is the main sterol of most fungi. Production of reactive oxygen species after the treatment of tobacco and tomato cells by nano-molar concentrations of ergosterol was previously observed as well as the activation of some stress activated mitogen-activated protein kinases on alfalfa cells. In this paper, the expression of some defence-related genes after the ergosterol treatment of tobacco Nicotiana tabacum plants is reported. The gene expression of pathogenesis related proteins of families PR1, PR3, PR5 and proteinase inhibitors of class I and II together with enzymes participating in the defence response, such as phenylalanine-ammonia lyase and sesquiterpene cyclase, were monitored by RT-qPCR. In addition, the concentrations of salicylic acid, an important signalling molecule, increased in time due to the enzyme activation. On the other hand, ergosterol did not provoke tissue necrosis and the possible cross-talk between the signalling pathways of salicylate and jasmonate was observed. Collected data shows that ergosterol is able to activate the expression of a number of defence genes and could increase resistance against pathogens. 相似文献
17.
Blends of volatile chemicals emanating from cassava leaves infested by the cassava green mite were found to promote conidiation
of Neozygites tanajoae, an entomopathogenic fungus specific to this mite. Methyl salicylate (MeSA) is one compound frequently present in blends
of herbivore-induced plant volatiles (HIPV) as well as that of mite-infested cassava. Here, we investigated the effect of
methyl salicylate in its pure form on the production of pre-infective spores (conidia), and the germination of these spores
into infective spores (capilliconidia), by a Brazilian isolate and a Beninese isolate of N. tanajoae. Mummified mites previously infected by the fungal isolates were screened under optimal abiotic conditions for sporulation
inside tightly closed boxes with or without methyl salicylate diffusing from a capillary tube. Production of conidia was consistently
higher (37%) when the Beninese isolate was exposed to MeSA than when not exposed to it (305.5 ± 52.62 and 223.2 ± 38.13 conidia
per mummy with and without MeSA, respectively). MeSA, however, did not promote conidia production by the Brazilian isolate
(387.4 ± 44.74 and 415.8 ± 57.95 conidia per mummy with and without MeSA, respectively). Germination of the conidia into capilliconidia
was not affected by MeSA for either isolate (0.2%, 252.6 ± 31.80 vs. 253.0 ± 36.65 for the Beninese isolate and 4.2%, 268.5 ± 37.90
vs. 280.2 ± 29.43 for the Brazilian isolate). The effects of MeSA on the production of conidia were similar to those obtained
under exposure to the complete blends of HIPV for the case of the Beninese isolate, but dissimilar (no promoting effect of
MeSA) for the case of the Brazilian isolate. This shows that MeSA, being one compound out of many HIPV, can be a factor promoting
sporulation of N. tanajoae, but it may not be the only factor as its effect varies with the fungal isolate under study. 相似文献
18.
Thermotoga hypogea is an extremely thermophilic anaerobic bacterium capable of growing at 90°C. It uses carbohydrates and peptides as carbon
and energy sources to produce acetate, CO2, H2, l-alanine and ethanol as end products. Alcohol dehydrogenase activity was found to be present in the soluble fraction of T. hypogea. The alcohol dehydrogenase was purified to homogeneity, which appeared to be a homodimer with a subunit molecular mass of
40 ± 1 kDa revealed by SDS-PAGE analyses. A fully active enzyme contained iron of 1.02 ± 0.06 g-atoms/subunit. It was oxygen
sensitive; however, loss of enzyme activity by exposure to oxygen could be recovered by incubation with dithiothreitol and
Fe2+. The enzyme was thermostable with a half-life of about 10 h at 70°C, and its catalytic activity increased along with the
rise of temperature up to 95°C. Optimal pH values for production and oxidation of alcohol were 8.0 and 11.0, respectively.
The enzyme had a broad specificity to use primary alcohols and aldehydes as substrates. Apparent K
m values for ethanol and 1-butanol were much higher than that of acetaldehyde and butyraldehyde. It was concluded that the
physiological role of this enzyme is likely to catalyze the reduction of aldehydes to alcohols. 相似文献
19.
采用cDNA-AFLP和RACE技术从小白菜中克隆得到泛素结合酶E2基因(ubiquitin conjugating enzyme E2),命名为BcUBCE2。序列分析表明,BcUBCE2基因cDNA全长830bp,包含1个456bp的开放阅读框,编码152个氨基酸。结构分析发现,该序列包含一个泛素结合酶E2活性位点和一个高度保守的半胱氨酸。进化分析显示,小白菜BcUBCE2蛋白同拟南芥E2蛋白的亲缘关系最近。qRT-PCR分析表明,BcUBCE2基因在小白菜根、茎、叶中均有表达,铜处理10d时BcUBCE2基因的表达量最高。研究认为,BcUBCE2基因可能在铜胁迫响应中发挥重要作用。 相似文献
20.
Yurchenko JV Budilov AV Deyev SM Khromov IS Sobolev AY 《Molecular genetics and genomics : MGG》2003,270(1):87-93
A gene that codes for an alkaline phosphatase was cloned from the thermophilic bacterium Meiothermus ruber, and its nucleotide sequence was determined. The deduced amino acid sequence indicates that the enzyme precursor including the putative signal sequence is composed of 503 amino acid residues and has an estimated molecular mass of 54,229 Da. Comparison of the peptide sequence with that of the prototype alkaline phosphatase from Escherichia coli revealed conservation of the regions in the vicinity of the corresponding phosphorylation site and metal binding sites. The protein was expressed in E. coli and its enzymatic properties were characterized. In the absence of exogenously added metal ions, activity was negligible; to obtain maximal activity, addition of free Mg2+ ions was required. Zn2+ ions had an inhibitory effect on the activity of the M. ruber enzyme. The pH and temperature optima for activity were found to be 11.0 and 62°C, respectively. The enzyme was moderately thermostable: it retained about 50% activity after incubation for 6 h at 60°C, whereas at 80°C it was completely inactivated within 2 h. The Michaelis constant for cleavage of 4-nitrophenylphosphate was 0.055 mM. While having much in common with other alkaline phosphatases, the M. ruber enzyme presents some unique features, such as a very narrow pH range for activity and an absolute requirement for magnesium for activity.Communicated by G. P. Georgiev 相似文献