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  • 1
    Electronic Resource
    Electronic Resource
    Biochemical evidence for multiple forms of acetohydroxy acid synthase in Spirulina platensis (1991)
    Springer
    Archives of microbiology 155 (1991), S. 298-302 
    Details
    ISSN: 1432-072X
    Keywords: Acetohydroxy acid synthase ; Acetolactate synthase ; Isozymes ; Isoleucine-leucine-valine biosynthesis ; Spirulina ; Cyanobacteria ; Flavin adenine dinucleotide requirement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two isoforms of acetohydroxy acid synthase (AHAS), the first enzyme of the branched-chain amino acids biosynthetic pathway, were detected in cell-free extracts of the cyanobacterium Spirulina platensis and separated both by ion-exchange chromatography and by hydrophobic interaction. Several biochemical properties of the two putative isozymes were analysed and it was found that they differ for pH optimum, FAD requirement for both activity and stability, and for heat lability. The results were partially confirmed with the characterization of the enzyme extracted from a recombinant Escherichia coli strain transformed with one subcloned S. platensis coli strain transformed with one subcloned S. platensis AHAS gene. The approximate molecular mass of both AHAS activities, estimated by gel filtration, indicates that they are distinct isozymes and not different oligomeric species or aggregates of identical subunits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00252216
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular cloning and expression of Spirulina platensis acetohydroxy acid synthase genes in Escherichia coli (1991)
    Springer
    Archives of microbiology 155 (1991), S. 360-365 
    Details
    ISSN: 1432-072X
    Keywords: Acetohydroxy acid synthase ; Ilv genes ; Cyanobacteria ; Isoleucine ; Leucine ; Valine biosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The coding sequence for Spirulina platensis acetohydroxy acid synthase (AHAS, EC 4.1.3.18) is shown to be contained within a 4.2 Kb ClaI fragment (ilvX) that has been cloned from a recombinant lambda library. This fragment was able to complement a suitable mutant of Escherichia coli when inserted into the ClaI site of plasmid pAT153 in either orientation, demonstrating that transcription of ilvX originated within the cloned fragment. The probe used for hybridization experiments was the corresponding gene from Anabaena sp. PCC7120. The same probe allowed us to identify a second putative gene encoding AHAS in the S. platensis genomic library.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00243456
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  • 3
    Electronic Resource
    Electronic Resource
    A metal-independent hydrolase from a Penicillium oxalicum strain able to use phosphonoacetic acid as the only phosphorus source (2003)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 222 (2003), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A Penicillium oxalicum strain was capable of the phosphate-sensitive utilization of phosphonoacetic acid as the sole source of phosphorus. A carbon-to-phosphorus bond-cleavage enzyme yielding acetic acid and inorganic phosphate was detected and characterized in extracts from cells grown on this phosphonate. Contrary to bacterial phosphonoacetate hydrolases, the fungal enzyme neither required nor was stimulated by divalent cations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0378-1097(03)00301-X
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  • 4
    Electronic Resource
    Electronic Resource
    Enhanced and feedback-resistant γ-glutamyl kinase activity of an Escherichia coli transformant carrying a mutated proB gene of Streptococcus thermophilus (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 182 (2000), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We used a PCR-based method to generate a single base pair mutation in the proB gene of Streptococcus thermophilus, which replaced an aspartic acid with a glycine residue at position 192 of the first proline biosynthetic enzyme γ-glutamyl kinase. This was the first identified mutation in amino acid biosynthesis in S. thermophilus to our knowledge. The mutation caused an enhanced, feedback-resistant γ-glutamyl kinase activity and conferred an analogue-resistant phenotype to an Escherichia coli transformant containing the mutated gene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2000.tb08888.x
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  • 5
    Electronic Resource
    Electronic Resource
    Expression of Δ1-pyrroline-5-carboxylate dehydrogenase and proline/arginine homeostasis in Solanum tuberosum (2000)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 110 (2000), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Polyclonal antibodies raised in mouse against purified potato Δ1-pyrroline-5-carboxylate dehydrogenase (P5C-DH, EC 1.5.1.12), which catalyses the last step in the catabolism of both proline and arginine, were used to investigate the expression of this enzyme. Distribution of P5C-DH in potato (Solanum tuberosum L. cv. Desiree) organs was studied at different stages during plant development. Variations in enzyme level were determined in axenically grown plantlets following the addition of exogenous proline, and in cell suspension cultures under hyperosmotic stress and after its relief. Free proline and arginine levels were also quantified, and compared to those of the enzyme. Results were consistent with a developmental, but not with an environmental, control of P5C-DH expression. The possible involvement of specific isozymes in proline and arginine oxidation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2000.110103.x
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  • 6
    Electronic Resource
    Electronic Resource
    Two δ1-pyrroline-5-carboxylate dehydrogenase isoforms are expressed in cultured Nicotiana plumbaginifolia cells and are differentially modulated during the culture growth cycle (1997)
    Springer
    Planta 202 (1997), S. 242-248 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Enzyme regulation ; Nicotiana ; Proline catabolism ; δ1-Pyrroline-5-carboxylate (isoforms) ; Water/salt stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. δ1-Pyrroline-5-carboxylate (P5C) dehydrogenase (EC 1.5.1.12) activity was measured in extracts from cultured tobacco (Nicotiana plumbaginifolia Viviani) cells. Two putative isozymes were resolved by anion-exchange fast protein liquid chromatography. These enzyme forms showed different patterns of expression during the culture growth cycle: activity-I increased in exponentially growing cells and declined rapidly in late logarithmic phase, while activity-II was found at substantial level only in cells which were entering the stationary phase. Both P5C dehydrogenases were partially purified and characterized with respect to kinetic and biochemical properties. They showed similar molecular masses as judged from retention patterns upon gel-filtration chromatography. The in vitro activity of both enzymes had a broad maximum around pH 7.4, and was progressively inhibited by Cl− at concentrations ranging from 0.1 to 1 M. A pronounced difference was found between their apparent K m values for the two substrates, P5C and NAD+, the higher affinities being shown by activity-I. Regulation of P5C dehydrogenase during salt-stress-induced proline accumulation was investigated. Following the addition of 175 mM NaCl to the culture medium the level of activity-I was substantially unaffected, while the specific activity of the other isozyme failed to increase even after the onset of the stationary phase of growth. Possible roles for P5C dehydrogenase isozymes in proline and arginine metabolism are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050125
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  • 7
    Electronic Resource
    Electronic Resource
    Glyphosate tolerance in maize (Zea mays L.). 1. Differential response among inbred lines (1995)
    Springer
    Euphytica 82 (1995), S. 157-164 
    Details
    ISSN: 1573-5060
    Keywords: EPSP synthase ; glyphosate ; herbicide tolerance ; natural variation ; Zea mays ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Variation in susceptibility to the safe broad-spectrum herbicide glyphosate was investigated in maize. Eleven inbred lines, grown in a growth chamber, were evaluated for their tolerance to the herbicide at 2.4 mM (0.2 kg a.i. in 400 I ha-1 of water). Following treatment with glyphosate at the three-leaf stage, significant variation in damage, expressed as visual injury ratings scored 7, 14 and 21 days after the application of the herbicide, was found. Effects on dry weight and shoot height were consistent with visual scores and the carbon-exchange rate was found to be a sensitive index of differential injury. Biochemical characterization of 5-enol-pyruvyl-shikimate-3-phosphate (EPSP) synthase, the main target of the herbicide, ruled out the possibility that this differential susceptibility was due to variations in the sensitivity of the enzyme. On the contrary, a positive correlation was found between in vivo tolerance and EPSP synthase levels, measured at different stages during seedling growth. This result suggests that a naturally occurring difference in EPSP synthase levels in the tissues may contribute to the differential response observed in vivo in maize inbreds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027062
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  • 8
    Electronic Resource
    Electronic Resource
    Deregulated branched-chain amino acid synthesis in a Nicotiana plumbaginifolia cell line resistant to valine (1996)
    Springer
    Plant growth regulation 19 (1996), S. 241-248 
    Details
    ISSN: 1573-5087
    Keywords: acetohydroxyacid synthase ; branched-chain amino acids/cell growth inhibitors ; enzyme level regulation ; valine tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A Nicotiana plumbaginifolia cell line able to grow in the presence of high doses of valine was isolated following γ-rays mutagenesis. The selected clone, named D5R5, showed a growth rate higher than that of wild-type. It was less sensitive also to an equimolar mixture of the three branched-chain amino acids, but did not display cross-resistance to isoleucine and leucine. The increased tolerance was due to neither a reduced valine uptake, nor a modification in the level or sensitivity to feed-back inhibition by valine of the first common enzyme (and the main regulative site) in isoleucine, leucine and valine synthesis, acetohydroxyacid synthase (AHAS). When wild-type cells were fed with valine or equimolar mixtures of the three aminoacids, a decrease in AHAS level was found. On the contrary, the level of extractable AHAS activity from D5R5 cells was significantly less affected by similar treatments, suggesting that some alteration in enzyme modulation mechanism(s) could account for valine resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00037797
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  • 9
    Electronic Resource
    Electronic Resource
    Glyphosate tolerance in maize (Zea mays L.). 2. Selection and characterization of a tolerant somaclone (1995)
    Springer
    Euphytica 82 (1995), S. 165-173 
    Details
    ISSN: 1573-5060
    Keywords: glyphosate ; herbicide tolerance ; non-target effects ; somaclonal variation ; Zea mays ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The progeny of 104 regenerated maize plants were screened for tolerance to the safe broad-spectrum herbicide glyphosate during seed germination and early growth. Seven somaclones showed varying degrees of resistance to the application of the herbicide at 1.2 mM (0.1 kg a.i. in 400 1 ha-1 of water). Plants capable of a normal growth following treatment with 2.4 mM (0.2 kg ha-1) glyphosate at the three leaf stage were selfed, and their progeny analyzed. A family able to tolerate the exposure to glyphosate at 2.4 mM was isolated and shown to maintain a photosynthetic rate comparable with control after the application of the herbicide. The selfed progeny of the tolerant somaclone was characterized as to the properties of two targets of glyphosate, the shikimate pathway enzymes 5-enol-pyruvyl-shikimate-3-phosphate (EPSP) synthase and 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase. In vitro tests ruled out the possibility that the tolerance was due to altered forms of these enzymes. Families showed significant variability with regard to EPSP and DAHP synthase levels, measured at different stages during seedling growth; however, not even these traits were correlated with in vivo response to glyphosate. The possible role of other physiological processes in determining the increased tolerance to the herbicide is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027063
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  • 10
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    Synthesis of Rubrolide Analogues as New Inhibitors of the Photosynthetic Electron Transport Chain (2012)
    American Chemical Society
    Details
    Publication Date: 2012-10-12
    Print ISSN: 0021-8561
    Electronic ISSN: 1520-5118
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Published by American Chemical Society
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