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1.
Choline dehydrogenase (CD), the first enzyme of the glycine betaine synthetic pathway, was measured in a mitochondrial lysate from gill tissue from Atlantic and Chesapeake Bay oysters acclimated to both 350 and 750 mosm. CD from both populations functions at its maximum rate at 30 degrees C and pH 8.75. Although CD from both populations has a similar affinity for its substrate, choline (K(m) = 15.7 mM), CD V(max) from Atlantic oysters is twice that from Bay oysters. In addition, the CD K(m )doubles and the V(max) increases four-fold in both oyster populations acclimated to 750 mosm. CD activity is competitively inhibited by both betaine aldehyde and glycine betaine. The differences in CD kinetics between the two oyster populations help to account for the lower glycine betaine synthesis rates and concentrations in Chesapeake Bay oysters. CD cannot function rapidly enough to saturate the enzyme, betaine aldehyde dehydrogenase (BADH), immediately downstream, and, therefore, CD kinetics limit the rate of glycine betaine synthesis in oysters. J. Exp. Zool. 286:250-261, 2000.  相似文献   

2.
In Escherichia coli the osmoprotective compound glycine betaine is produced from choline by two enzymes; choline dehydrogenase (CDH) oxidizes choline to betaine aldehyde and then further on to glycine betaine, while betaine aldehyde dehydrogenase (BADH) facilitates the conversion of betaine aldehyde to glycine betaine. To evaluate the importance of BADH, a BADH/CDH fusion enzyme was constructed and expressed in E. coli and in Nicotiana tabacum. The fusion enzyme displayed both enzyme activities, and a coupled reaction could be measured. The enzyme was characterized regarding molecular weight and the dependence of the enzyme activities on environmental factors (salt, pH, and poly(ethylene glycol) addition). At high choline concentrations, E. coli cells expressing BADH/CDH were able to grow to higher final densities and to accumulate more glycine betaine than cells expressing CDH only. The intracellular glycine betaine levels were almost 5-fold higher for BADH/CDH when product concentration was related to CDH activity. Also, after culturing the cells at high NaCl concentrations, more glycine betaine was accumulated. On medium containing 20 mM choline, transgenic tobacco plants expressing BADH/CDH grew considerably faster than vector-transformed control plants.  相似文献   

3.
Betaine aldehyde dehydrogenase (BADH; EC 1.2.1.8) is an important enzyme that catalyzes the last step in the synthesis of glycine betaine, a compatible solute accumulated by many plants under various abiotic stresses. In barley ( Hordeum vulgare L.), we reported previously the existence of two BADH genes ( BBD1 and BBD2 ) and their corresponding proteins, peroxisomal BADH (BBD1) and cytosolic BADH (BBD2). To investigate their enzymatic properties, we expressed them in Escherichia coli and purified both proteins. Enzymatic analysis indicated that the affinity of BBD2 for betaine aldehyde was reasonable as other plant BADHs, but BBD1 showed extremely low affinity for betaine aldehyde with apparent Km of 18.9 μ M and 19.9 m M , respectively. In addition, Vmax/Km with betaine aldehyde of BBD2 was about 2000-fold higher than that of BBD1, suggesting that BBD2 plays a main role in glycine betaine synthesis in barley plants. However, BBD1 catalyzed the oxidation of ω-aminoaldehydes such as 4-aminobutyraldehyde and 3-aminopropionaldehyde as efficiently as BBD2. We also found that both BBDs oxidized 4- N -trimethylaminobutyraldehyde and 3- N -trimethylaminopropionaldehyde.  相似文献   

4.
Certain higher plants synthesize and accumulate glycine betaine, a compound with osmoprotectant properties. Biosynthesis of glycine betaine proceeds via the pathway choline betaine aldehyde glycine betaine. Plants such as tobacco (Nicotiana tabacum L.) which do not accumulate glycine betaine lack the enzymes catalyzing both reactions. As a step towards engineering glycine betaine accumulation into a non-accumulator, spinach and sugar beet complementary-DNA sequences encoding the second enzyme of glycine-betaine synthesis (betaine aldehyde dehydrogenase, BADH, EC 1.2.1.8) were expressed in tobacco. Despite the absence of a typical transit peptide, BADH was targeted to the chloroplast in leaves of transgenic plants. Levels of extractable BADH were comparable to those in spinach and sugar beet, and the molecular weight, isoenzyme profile and K m for betaine aldehyde of the BADH enzymes from transgenic plants were the same as for native spinach or sugar beet BADH. Transgenic plants converted supplied betaine aldehyde to glycine betaine at high rates, demonstrating that they were able to transport betaine aldehyde across both the plasma membrane and the chloroplast envelope. The glycine betaine produced in this way was not further metabolized and reached concentrations similar to those in plants which accumulate glycine betaine naturally. Betaine aldehyde was toxic to non-transformed tobacco tissues whereas transgenic tissues were resistant due to detoxification of betaine aldehyde to glycine betaine. Betaine aldehyded ehydrogenase is therefore of interest as a potential selectable marker, as well as in the metabolic engineering of osmoprotectant biosynthesis.Abbreviations BADH betaine aldehyde dehydrogenase - bp base pairs - FAB-MS fast atom bombardment-mass spectrometry - GAPDH NADP-linked glyceraldehyde-3-phosphate dehydrogenase We thank Dr. G. An for the gift of the vector pGA643 and Mr. Sylvain Lebeurier for help in maintaining plants. This work was supported, in part, by grants from the Natural Sciences and Engineering Research Council of Canada, the Rockefeller Foundation, and the U.S. Department of Agriculture, and by gifts from CIBAGEIGY Biotechnology.  相似文献   

5.
Glycine betaine is an osmoprotectant found in many organisms, including bacteria and higher plants. The bacterium Escherichia coli produces glycine betaine by a two-step pathway where choline dehydrogenase (CDH), encoded by betA, oxidizes choline to betaine aldehyde which is further oxidized to glycine betaine by the same enzyme. The second step, conversion of betaine aldehyde into glycine betaine, can also be performed by the second enzyme in the pathway, betaine aldehyde dehydrogenase (BADH), encoded by betB. Transformation of tobacco (Nicotiana tabacum), a species not accumulating glycine betaine, with the E. coli genes for glycine betaine biosynthesis, resulted in transgenic plants accumulating glycine betaine. Plants producing CDH were found to accumulate glycine betaine as did F1 progeny from crosses between CDH- and BADH-producing lines. Plants producing both CDH and BADH generally accumulated higher amounts of glycine betaine than plants producing CDH alone, as determined by 1H NMR analysis. Transgenic tobacco lines accumulating glycine betaine exhibited increased tolerance to salt stress as measured by biomass production of greenhouse-grown intact plants. Furthermore, experiments conducted with leaf discs from glycine betaine-accumulating plants indicated enhanced recovery from photoinhibition caused by high light and salt stress as well as improved tolerance to photoinhibition under low temperature conditions. In conclusion, introduction of glycine betaine production into tobacco is associated with increased stress tolerance probably partly due to improved protection of the photosynthetic apparatus.  相似文献   

6.
Molecular and Cellular Biochemistry - The enzyme betaine aldehyde dehydrogenase (BADH EC 1.2.1.8) catalyzes the synthesis of glycine betaine (GB), an osmolyte and osmoprotectant. Also, it...  相似文献   

7.
Betaine aldehyde dehydrogenase in sorghum.   总被引:25,自引:0,他引:25       下载免费PDF全文
The ability to synthesize and accumulate glycine betaine is wide-spread among angiosperms and is thought to contribute to salt and drought tolerance. In plants glycine betaine is synthesized by the two-step oxidation of choline via the intermediate betaine aldehyde, catalyzed by choline monooxygenase and betaine aldehyde dehydrogenase (BADH). Two sorghum (Sorghum bicolor) cDNA clones, BADH1 and BADH15, putatively encoding betaine aldehyde dehydrogenase were isolated and characterized. BADH1 is a truncated cDNA of 1391 bp. BADH15 is a full-length cDNA clone, 1812 bp in length, predicted to encode a protein of 53.6 kD. The predicted amino acid sequences of BADH1 and BADH15 share significant homology with other plant BADHs. The effects of water deficit on BADH mRNA expression, leaf water relations, and glycine betaine accumulation were investigated in leaves of preflowering sorghum plants. BADH1 and BADH15 mRNA were both induced by water deficit and their expression coincided with the observed glycine betaine accumulation. During the course of 17 d, the leaf water potential in stressed sorghum plants reached -2.3 MPa. In response to water deficit, glycine betaine levels increased 26-fold and proline levels increased 108-fold. In severely stressed plants, proline accounted for > 60% of the total free amino acid pool. Accumulation of these compatible solutes significantly contributed to osmotic potential and allowed a maximal osmotic adjustment of 0.405 MPa.  相似文献   

8.
Betaine aldehyde dehydrogenase (BADH) catalyzes the last step in the synthesis of the osmoprotectant glycine betaine from choline. Although betaine aldehyde has been thought to be a specific substrate for BADH, recent studies have shown that human and sugar beet BADHs also catalyze the oxidation of omega-aminoaldehydes. To characterize the kinetic and stability properties of spinach BADH, five kinds of expression vectors encoding full length, mature, E103Q, E103K, and chimera BADHs were constructed. These enzymes together with Escherichia coli BADH were expressed in E. coli and purified. The affinities for betaine aldehyde were similar in the spinach and E. coli BADHs, whereas those for omega-aminoaldehydes were higher in spinach BADH than in E. coli BADH. A chimera BADH in which part of the Rossmann type fold in the spinach BADH was replaced with that of E. coli BADH, showed properties which resembled spinach BADH more than E. coli BADH. The spinach E103K mutant was almost inactive, whereas the E103Q mutant showed a similar activity for the oxidation of betaine aldehyde to that of wild type BADH, but a lower affinity for omega-aminoaldehydes. All spinach BADHs were dimers whereas E. coli BADH was a tetramer. E. coli BADH was more stable at high temperature than spinach BADHs. The E103Q mutant was most labile to high temperature. These properties are discussed in relation to the structure of spinach BADH.  相似文献   

9.
Members of the Chenopodiaceae, such as sugar beet and spinach, accumulate glycine betaine in response to salinity or drought stress. The last enzyme in the glycine betaine biosynthetic pathway is betaine aldehyde dehydrogenase (BADH). In sugar beet the activity of BADH was found to increase two- to four-fold in both leaves and roots as the NaCl level in the irrigation solution was raised from 0 to 500 mM. This increase in BADH activity was paralleled by an increase in level of translatable BADH mRNA. Several cDNAs encoding BADH were cloned from a gt10 libary representing poly(A)+ RNA from salinized leaves of sugar beet plants, by hybridization with a spinach BADH cDNA. Three nearly full-length cDNA clones were confirmed to encode BADH by their nucleotide and deduced amino acid sequence identity to spinach BADH; these clones showed minor nucleotide sequence differences consistent with their being of two different BADH alleles. The clones averaged 1.7 kb and contained an open reading frame predicting a polypeptide of 500 amino acids with 83% identity to spinach BADH. RNA gel blot analysis of total RNA showed that salinization to 500 mM NaCl increased BADH mRNA levels four-fold in leaves and three-fold in the taproot. DNA gel blot analyses indicated the presence of at least two copies of BADH in the haploid sugar beet genome.  相似文献   

10.
Tobacco (Nicotianum tabacum L.) plants engineered to express a sugar beet (Beta vulgaris L.) betaine aldehyde dehydrogenase (BADH) cDNA acquired not only BADH activity, but also three other aldehyde dehydrogenase activities (those measured with 3-dimethylsulfoniopropionaldehyde, 3-aminopropionaldehyde, and 4-aminobutyraldehyde, all of which are natural products). This shows that BADH is not, as believed up to now, a substrate-specific enzyme and that its role may not be limited to glycine betaine synthesis.  相似文献   

11.
Concentrated urine formation in the kidney is accompanied by conditions that favor the accumulation of reactive oxygen species (ROS). Under hyperosmotic conditions, medulla cells accumulate glycine betaine, which is an osmolyte synthesized by betaine aldehyde dehydrogenase (BADH, EC 1.2.1.8). All BADHs identified to date have a highly reactive cysteine residue at the active site, and this cysteine is susceptible to oxidation by hydrogen peroxide. Porcine kidney BADH incubated with H(2)O(2) (0-500 μM) lost 25% of its activity. However, pkBADH inactivation by hydrogen peroxide was limited, even after 120 min of incubation. The presence of coenzyme NAD(+) (10-50 μM) increased the extent of inactivation (60%) at 120 min of reaction, but the ligands betaine aldehyde (50 and 500 μM) and glycine betaine (100 mM) did not change the rate or extent of inactivation as compared to the reaction without ligand. 2-Mercaptoethanol and dithiothreitol, but not reduced glutathione, were able to restore enzyme activity. Mass spectrometry analysis of hydrogen peroxide inactivated BADH revealed oxidation of M278, M243, M241 and H335 in the absence and oxidation of M94, M327 and M278 in the presence of NAD(+). Molecular modeling of BADH revealed that the oxidized methionine and histidine residues are near the NAD(+) binding site. In the presence of the coenzyme, these oxidized residues are proximal to the betaine aldehyde binding site. None of the oxidized amino acid residues participates directly in catalysis. We suggest that pkBADH inactivation by hydrogen peroxide occurs via disulfide bond formation between vicinal catalytic cysteines (C288 and C289).  相似文献   

12.
Aim Historical information about source populations of invasive species is often limited; therefore, genetic analyses are used. We compared inference about source populations from historical and genetic data for the oyster‐associated clam, Gemma gemma that invaded California from the USA Atlantic coast. Location Mid‐Atlantic (North Carolina, Maryland), Northeastern (New Jersey, New York, Massachusetts) and the California coasts (Elkhorn Slough, San Francisco Bay, Bolinas Lagoon, Tomales Bay, Bodega Harbor). Methods The documented history of transplantation of Eastern oysters to California was reviewed. Cytochrome c oxidase subunit I (COI) sequences from recent and archived clams were examined in a haplotype network. We used AMOVA to detect geographic genetic structure and a permutation test for significant reductions in diversity. Results Chesapeake Bay oysters were transplanted to New York prior to shipment to San Francisco Bay and from there to peripheral bays. Gemma in the Northeastern and Mid‐Atlantic regions were genetically differentiated. In California, populations in Bodega Harbor and Tomales Bay were genetically similar to those in the Mid‐Atlantic area while clams in San Francisco Bay, Elkhorn Slough and Bolinas Lagoon resembled populations in the Northeastern region. In California, genetic variation was not highest in San Francisco Bay despite greater magnitude of oyster plantings. Haplotypes varied over time in native and introduced populations. Main Conclusions Historical records and inferences from genetics agree that both Northeastern and Mid‐Atlantic regions were sources for Gemma in California. Only complex genetic hypotheses reconcile the strong segregation of haplotypes in California to the historical evidence of mixing in their proximate source (New York). These hypotheses include sorting of mixtures of haplotypes or selection in non‐native areas. Haplotype turnover in San Francisco and Massachusetts samples over time suggests that the sorting hypothesis is plausible. We suggest, however, that Gemma was introduced independently and recently to Tomales Bay and Bodega Harbor.  相似文献   

13.
Meng YL  Wang YM  Zhang B  Nii N 《Cell research》2001,11(3):187-193
INTRODUCTIONAmaranth is a C4 dicotyledonous mesophytecrop plant. A. tricofor is a major variety for veg-etable and ornamental crops, and is widely culti-vated in the wor1d. Osmoprotectant glycine betaine(GB) was detected in Amaranthaceae, A. HyPochon-driacus L[2] and A. Caudatus L[3, 4]. GB iswidespread and an effective osmoprotectant in manyplants[3]. We studied the photosynthetic adaptationmechanism of A. trico1or under salt stress due to ac-cumulation of GB[5].GB is synthesized …  相似文献   

14.
Bai  Xin  Zeng  Xing  Huang  Siqi  Liang  Jinsong  Dong  Liying  Wei  Yingnan  Li  Yue  Qu  Juanjuan  Wang  Zhenhua 《Plant and Soil》2019,436(1-2):527-541
Plant and Soil - Transgenic betaine aldehyde dehydrogenase (BADH) maize that overaccumulates glycine betaine (GB) is developed to enhance tolerance to salt stress, while the ecological risk of...  相似文献   

15.
Plant Aldehyde Dehydrogenase10 (ALDH10) enzymes catalyze the oxidation of ω-primary or ω-quaternary aminoaldehydes, but, intriguingly, only some of them, such as the spinach (Spinacia oleracea) betaine aldehyde dehydrogenase (SoBADH), efficiently oxidize betaine aldehyde (BAL) forming the osmoprotectant glycine betaine (GB), which confers tolerance to osmotic stress. The crystal structure of SoBADH reported here shows tyrosine (Tyr)-160, tryptophan (Trp)-167, Trp-285, and Trp-456 in an arrangement suitable for cation-π interactions with the trimethylammonium group of BAL. Mutation of these residues to alanine (Ala) resulted in significant K(m)(BAL) increases and V(max)/K(m)(BAL) decreases, particularly in the Y160A mutant. Tyr-160 and Trp-456, strictly conserved in plant ALDH10s, form a pocket where the bulky trimethylammonium group binds. This space is reduced in ALDH10s with low BADH activity, because an isoleucine (Ile) pushes the Trp against the Tyr. Those with high BADH activity instead have Ala (Ala-441 in SoBADH) or cysteine, which allow enough room for binding of BAL. Accordingly, the mutation A441I decreased the V(max)/K(m)(BAL) of SoBADH approximately 200 times, while the mutation A441C had no effect. The kinetics with other ω-aminoaldehydes were not affected in the A441I or A441C mutant, demonstrating that the existence of an Ile in the second sphere of interaction of the aldehyde is critical for discriminating against BAL in some plant ALDH10s. A survey of the known sequences indicates that plants have two ALDH10 isoenzymes: those known to be GB accumulators have a high-BAL-affinity isoenzyme with Ala or cysteine in this critical position, while non GB accumulators have low-BAL-affinity isoenzymes containing Ile. Therefore, BADH activity appears to restrict GB synthesis in non-GB-accumulator plants.  相似文献   

16.
Betaine aldehyde dehydrogenase (BADH; EC 1.2.1.8) is the enzyme that catalyzes the second step in the synthesis of the osmoprotectant, glycine betaine. NAD-dependent BADH was purified from Avena sativa shoots by DEAE Sephacel, hydroxyapatite, 5′-AMP Sepharose 4B, Mono Q and TSK-GEL column chromatographies to homogeneity by the criterion of native PAGE, and the properties of BADH were compared with those of aminoaldehyde dehydrogenase purified to homogeneity from A. sativa. The molecular mass estimated by both gel filtration using TSK-GEL column and Sephacryl S-200 was 120 and 115, kDa, respectively. The enzyme is a homodimer with a subunit molecular mass of 61 kDa as shown by SDS-PAGE. The pI value of the enzyme was found to be 6.3. The purified enzyme catalyzed not only the oxidation of betaine aldehyde (BAL), but also that of aminoaldehydes, 3-aminopropionaldehyde (APAL), 4-aminobutyraldehyde (ABAL), and 4-guanidinobutyraldehyde (GBAL). The K m values for BAL, APAL, ABAL and GBAL were 5×10−6, 5.4×10−7, 2.4×10−5 and 5×10−5 M, respectively. APAL showed substrate inhibition at a concentration of 0.1 mM. A fragment of BADH cleaved by V8 protease shared homology with other plant BADHs. Electronic Publication  相似文献   

17.
Betaine aldehyde dehydrogenase in plants   总被引:2,自引:0,他引:2  
Plant betaine aldehyde dehydrogenases (BADHs) have been the target of substantial research, especially during the last 20 years. Initial characterisation of BADH as an enzyme involved in the production of glycine betaine (GB) has led to detailed studies of the role of BADH in the response of plants to abiotic stress in vivo , and the potential for transgenic expression of BADH to improve abiotic stress tolerance. These studies have, in turn, yielded significant information regarding BADH and GB function. Recent research has identified the potential for BADH as an antibiotic-free marker for selection of transgenic plants, and a major role for BADH in 2-acetyl-1-pyrroline-based fragrance associated with jasmine and basmati style aromatic rice varieties.  相似文献   

18.
A search was undertaken for osmoprotective compounds for mouse hybridoma cell line 6H11 grown in culture. When the osmolality of the growth medium was increased above the normal osmolality of 330 mOsmol/kg, growth rates were decreased in a dose-dependent fashion, reaching zero when the osmolality of the medium reached approx. 435 mOsmol/kg through the addition of KCl (60 mM), or 510 mOsmol/kg through the addition of NaCl (100 mM), or sucrose (175 mM). For NaCl or sucrose-stressed cultures, the inclusion of glycine betaine, sarcosine, proline, glycine, or asparagine in the growth medium gave a moderate to strong osmoprotective effect, measured as the ability of these compounds to enhance cell growth rates under hyperosmotic conditions. Inclusion of dimethylglycine may also give a strong osmoprotective effect under these stress conditions.In KCl-stressed cell cultures, addition of glycine betaine, sarcosine, or dimethylglycine gave strong osmoprotective effects. Of 38 compounds tested during NaCl stress, 7 gave weak osmoprotective effects and 25 gave no osmoprotective effect. The osmoprotective compounds accumulated inside the stressed cells. Accumulation was completed after 4 to 8 h, reaching intracellular concentrations of approx. 0.27 pmol/cell, or 0.15 M, in NaCl stressed cells (100 mM NaCl added).Glycine betaine, dimethylglycine, and sarcosine accumulation was observed only when these protectants were included in the medium. For all osmoprotectants, a growth medium concentration between 5 and 30 mM gave the maximal protective effect, with the exception of dimethylglycine, for which the optimum concentration was approx. 65 mM. Osmoprotective effects obtained with glycine, sarcosine, dimethylglycine, and glycine betaine, indicate that the more methylated compounds are the most effective protectants.The cellular content of glycine betaine and the glycine betaine uptake rate increased with medium osmolality in a linear fashion. Glycine betaine uptake was described by a model comprising a saturable component obeying Michaelis-Menten kinetics and a nonsaturable component. K(m) and V(max) for glycine betaine uptake were determined at 420 mOsmol/kg (50 mM NaCl added) and 510 mOsmol/kg (100 mM NaCl added). A K(m) value of approx. 2.5 mM was obtained at both medium osmolalities, while V(max) increased from 0.010 pmol/cell . h to 0.018 pmol/cell . h as the osmolality of the growth medium was increased, indicating an effect of medium osmolality on the maximal rate of transport rather than on the affinity of the transporters for glycine betaine. Hybridoma cells were not able to utilize the glycine betaine precursors choline or glycine betaine aldehyde for osmoprotection, suggesting that the cells lack part, or all, of the choline-glycine betaine pathway or the appropriate uptake mechanism.The uptake rate for glycine in NaCl-stressed hybridoma cells was approx. four times higher than the uptake rate for glycine betaine. Furthermore, if equimolar amounts of glycine betaine, glycine, sarcosine, and proline were simultaneously added to NaCl-stressed cell cultures, the intracellular concentrations of glycine, proline, and sarcosine were significantly higher than the concentration of glycine betaine.A 40% increase in hybridoma cell volume was observed when the growth medium osmolality was increased from 300 to 520 mOsmol/kg. (c) 1994 John Wiley & Sons, Inc.  相似文献   

19.
Betaine aldehyde dehydrogenase (BADH) is a major oxidative enzyme that converts betaine aldehyde to glycine betaine (GB), an osmoprotectant compound in plants. Japonica rice (salt-sensitive) was genetically engineered to enhance salt tolerance by introducing the OsBADH1 gene from Indica rice (salt-tolerant), which is a GB accumulator. We produced transgenic rice plants overexpressing the modified OsBADH1 gene under the control of the maize ubiquitin promoter. The transgenic rice showed increased OsBADH1 gene expression and OsBADH1 enzyme production, resulting in the accumulation of GB. It also exhibited enhanced salt tolerance in immature and mature transgenic rice seedlings. The adverse effect of salt stress on seed germination, the growth of immature and mature seedlings, water status, and photosynthetic pigments was alleviated in transgenic seedlings.  相似文献   

20.
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