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  • Plasmopara halstedii  (3)
  • Phenylglyoxylate  (2)
  • Springer  (5)
  • American Chemical Society (ACS)
  • 1
    Electronic Resource
    Electronic Resource
    Anaerobic oxidation of phenylacetate and 4-hydroxyphenylacetate to benzoyl-coenzyme A and CO2 in denitrifying Pseudomonas sp. (1993)
    Springer
    Archives of microbiology 159 (1993), S. 563-573 
    Details
    ISSN: 1432-072X
    Keywords: Phenylacetate ; 4-Hydroxyphenylacetate ; Phenylglyoxylate ; Alpha-Oxidation ; Pseudomonas ; Oxidoreductase ; CoA ligase ; Benzoyl-CoA ; Anaerobic aromatic metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Anaerobic degradation of (4-hydroxy)phenylacetate in denitrifying Pseudomonas sp. was investigated. Evidence is presented for α-oxidation of the coenzyme A (CoA)-activated carboxymethyl side chain, a reaction which has not been described. The C6−C2 compounds are degraded to benzoyl-CoA and furtheron to CO2 via the following intermediates: Phenylacetyl-CoA, phenylglyoxylate, benzoyl-CoA plus CO2; 4-hydroxyphenylacetyl-CoA, 4-hydroxyphenylglyoxylate, 4-hydroxybenzoyl-CoA plus CO2, benzoyl-CoA. Trace amounts of mandelate possibly derived from mandelyl-CoA were detected during phenylacetate degradation in vitro. The reactions are catalyzed by (i) phenylacetate-CoA ligase which converts phenylacetate to phenylacetyl-CoA and by a second enzyme for 4-hydroxyphenylacetate; (ii) a (4-hydroxy)-phenylacetyl-CoA dehydrogenase system which oxidizes phenylacetyl-CoA to (4-hydroxy)phenylglyoxylate plus CoA; and (iii) (4-hydroxy)phenylglyoxylate: acceptor oxidoreductase (CoA acylating) which catalyzes the oxidative decarboxylation of (4-hydroxy)phenylglyoxylate to (4-hydroxy)benzoyl-CoA and CO2. (iv) The degradation of 4-hydroxyphenylacetate in addition requires the reductive dehydroxylation of 4-hydroxybenzoyl-CoA to benzoyl-CoA, catalyzed by 4-hydroxybenzoyl-CoA reductase (dehydroxylating). The whole cell regulation of these enzyme activities supports the proposed pathway. An ionic mechanism for anaerobic α-oxidation of the CoA-activated carboxymethyl side chain is proposed. Phenylacetic acids are plant constituents and in addition are formed from a large variety of natural aromatic compounds by microorganisms; their degradation therefore plays a significant role in nature, as illustrated in the preceding paper (Mohamed and Fuchs 1993). We have investigated and purified an enzyme which catalyzes the first step in the anaerobic degradation of phenylacetate in a denitrifying Pseudomonas sp. Phenylacetate is converted to phenylacetyl-CoA by phenylacetate-CoA ligase (AMP forming). The postulated function of this enzyme is corroborated by the strict regulation of its expression. 4-Hydroxyphenylacetate appears to be similarly activated by an independent enzyme prior to further degradation. We have suggested before that phenylacetyl-CoA is anaerobically converted by α-oxidation of the side chain to phenylglyoxylate1, which is oxidatively decarboxylated to benzoyl-CoA plus CO2 (Seyfried et al. 1991; Dangel et al. 1991). 4-Hydroxyphenylacetate was proposed to be similarly oxidized to 4-hydroxybenzoyl-CoA plus CO2, followed by reductive dehydroxylation to benzoyl-CoA. The evidence was not presented in full, and the crucial α-oxidation was not demonstrated in vitro. We present here ample evidence for this pathway. A hypothetical mechanism is proposed by which the oxidation of the α-methylene group to an α-carbonyl group may occur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249036
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  • 2
    Electronic Resource
    Electronic Resource
    Differential induction of enzymes involved in anaerobic metabolism of aromatic compounds in the denitrifying bacterium Thauera aromatica (1998)
    Springer
    Archives of microbiology 170 (1998), S. 120-131 
    Details
    ISSN: 1432-072X
    Keywords: Key words Anaerobic aromatic metabolism ; Benzoyl-CoA reductase ; Phenylphosphate carboxylase ; 4-Hydroxybenzoyl-CoA reductase ; 2-Aminobenzoate ; Phenylalanine ; Phenylacetyl-CoA ; Phenylglyoxylate ; Toluene ; CoA ligase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Differential induction of enzymes involved in anaerobic metabolism of aromatic substrates was studied in the denitrifying bacterium Thauera aromatica. This metabolism is divided into (1) peripheral reactions transforming the aromatic growth substrates to the common intermediate benzoyl-CoA, (2) the central benzoyl-CoA pathway comprising ring-reduction of benzoyl-CoA and subsequent β-oxidation to 3-hydroxypimelyl-CoA, and (3) the pathway of β-oxidation of 3-hydroxypimelyl-CoA to three acetyl-CoA and CO2. Regulation was studied by three methods. 1. Determination of protein patterns of cells grown on different substrates. This revealed several strongly substrate-induced polypeptides that were missing in cells grown on benzoate or other intermediates of the respective metabolic pathways. 2. Measurement of activities of known enzymes involved in this metabolism in cells grown on different substrates. The enzyme pattern found is consistent with the regulatory pattern deduced from simultaneous adaptation of cells to utilisation of other aromatic substrates. 3. Immunological detection of catabolic enzymes in cells grown on different substrates. Benzoate-CoA ligase and 4-hydroxybenzoate-CoA ligase were detected only in cells yielding the respective enzyme activity. However, presence of the subunits of benzoyl-CoA reductase and 4-hydroxybenzoyl-CoA reductase was also recorded in some cell batches lacking enzyme activity. This possibly indicates an additional level of regulation on protein level for these two reductases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050623
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  • 3
    Electronic Resource
    Electronic Resource
    Colocation of downy mildew (Plasmopara halstedii) resistance genes in sunflower (Helianthus annuus L.) (1996)
    Springer
    Euphytica 91 (1996), S. 225-228 
    Details
    ISSN: 1573-5060
    Keywords: bulked segregant analysis ; Helianthus annuus ; linkage ; Plasmopara halstedii ; resistance genes ; RFLP ; sunflower ; downy mildew
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The Pl6 locus in the inbred sunflower (Helianthus annuus L.) line HA335 giving resistance to French races of downy mildew (Plasmopara halstedii (Farl.) Berl. & de Toni. was localized by molecular techniques. A bulked segregant analysis was made on the F2 progeny from a cross between this line and H52, a downy mildew susceptible line. The resistance gene in HA335 was found to have the same linked RFLP marker loci as those determined for Pl1 (resistance to race 1 in the line RHA266) on linkage group 1 of the consensus RFLP map of the cultivated sunflower. Pl1 and Pl6 thus appear either to be allelic or closely linked. The implications for sunflower breeding are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021074
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  • 4
    Electronic Resource
    Electronic Resource
    Accumulation of Defense Related Transcripts in Sunflower Hypocotyls (Helianthus annuus L.) Infected with Plasmopara halstedii (1999)
    Springer
    European journal of plant pathology 105 (1999), S. 333-340 
    Details
    ISSN: 1573-8469
    Keywords: chitinase ; defense gene ; Helianthus annuus ; PAL ; Plasmopara halstedii ; ubiquitin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A cDNA clone encoding a sunflower chitinase was obtained using degenerated primers in PCR amplifications and RACE procedures. This clone, a phenylalanine ammonia-lyase (PAL) clone and ubiquitin clone were used to analyse the resistance of sunflower (Helianthus annuus) to downy mildew. The differential regulation of amounts of PAL (involved in the general pathway of phenylpropanoid synthesis), chitinase (a pathogenesis-related protein) and ubiquitin (involved in proteolytic pathways) mRNA was studied in hypocotyls during the early stages after an aerial infection of sunflower inbred line RHA274 with zoospores from either race 1 (incompatible, host resistant) or race B (compatible, host susceptible) of Plasmopara halstedii. Northern analyses showed that transcript levels of PAL, chitinase and ubiquitin were rapidly and strongly increased after infection in incompatible interactions but not in the compatible ones, suggesting that regulation of these mRNAs is an important component of the resistance mechanisms in sunflower.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008770008117
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  • 5
    Electronic Resource
    Electronic Resource
    Microscopical studies of the effect of metalaxyl on the interaction between sunflower,Helianthus annuus L. and downy mildew,Plasmopara halstedii (1995)
    Springer
    European journal of plant pathology 101 (1995), S. 399-404 
    Details
    ISSN: 1573-8469
    Keywords: Helianthus annuus ; hypersensitivity ; metalaxyl ; Plasmopara halstedii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The mode of action of the fungicide metalaxyl againstPlasmopara halstedii, the causal agent of sunflower downy mildew, was studied following its application before, during and after artificial contamination of seedlings. The development of the fungus within the treated seedlings was examined microscopically and compared to that occuring in untreated genetically susceptible or resistant genotypes. Hypersensitive-like reactions and necrotic zones leading to the inhibition of fungus growth within the hypocotyl were observed for the three modes of application. This suggests that sunflower defence mechanisms activated by genetical resistance are also involved in the control of downy mildew by metalaxyl.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01874853
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