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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 28 (1989), S. 7446-7452 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We have isolated 5 cDNA clones (din2,din6, din9, din10 and din11) corresponding to genes, the transcripts of which accumulated in leaves of Arabidopsisthaliana kept in the dark. These cDNA clones encode proteins similar to β-glucosidase (EC 3.2.1.21, din2), asparagine synthetase (EC 6.3.5.4, din6), phosphomannose isomerase (EC 5.3.1.8, din9), seed imbibition protein (din10) and 2-oxoacid-dependent dioxygenases (din11). Accumulation of the transcripts from din6 and din10 occurred within 3 h after plants were transferred to darkness. The transcripts from din2,din9 and din11 were only detected after 24 h of dark treatment. We also observed the accumulation of the din transcripts in senescing leaves. Application of a photosynthesis inhibitor, 3-(3,4-dichlorophenyl)-1-1-dimethyl-urea, induced the expression of the din genes under illumination. Application of sucrose to detached leaves suppressed the accumulation of the din transcripts in the dark. These results indicate that expression of these genes partly depends on cellular sugar level. The sugar-modulated expression of the din genes suggests that dark-induced expression of these genes might be related to sugar starvation occurring in leaf cells in the dark, when the photosynthesis is hindered.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5028
    Keywords: cDNA ; chloroplast ; fatty acid unsaturation ; glycerolipid biosynthesis ; Spinacia oleracea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-5028
    Keywords: Brassica napus ; CDP-choline ; cytidylyltransferase ; freezing stress ; phosphatidylcholine ; yeast mutant complementation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract CTP: phosphocholine cytidylyltransferase is a rate-limiting enzyme in biosynthesis of phosphatidylcholine in plant cells. We have isolated four cDNAs for the cytidylyltransferase from a root cDNA library of Brassica napus by complementation in a yeast cct mutant. The deduced amino-acid sequences of the B. napus enzymes resembled rat and yeast enzymes in the central domain. Although all cytidylyltransferases ever cloned from B. napus and other organisms were predicted to be structurally hydrophilic, the yeast cct mutant transformed with one of the B. napus cDNA clones restored the cytidylyltransferase activity in the microsomal fraction as well as in the soluble fraction. These results are consistent with a recent view that yeast cells contained a machinery for targeting the yeast cytidylyltransferase to membranes, and may indicate that the B. napus enzyme was compatible with the machinery.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-5028
    Keywords: acyl-(acyl-carrier-protein) hydrolase ; chloroplast protein ; Cucurbita moschata ; fatty acid ; lipid synthesis ; thioesterase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Acyl-(acyl-carrier-protein) hydrolase (EC 3.1.2.14) releases fatty acids from the end-product of fatty acid synthesis in plastids for the subsequent synthesis of glycerolipids in the cytoplasm. Isoelectric focusing of chloroplast stroma proteins from squash cotyledons suggested that there were at least three isomeric forms of acyl-(acyl-carrier-protein) hydrolase having pI values of 4.5, 5.3 and 7.8. The pI 4.5 and pI 5.3 forms showed maximum activity at pH 9.8 whereas the activity of the pI 7.8 form increased within the range 6.2 to 10.2 but no optimum was seen. The pI 4.5 form was purified 100 000-fold from squash cotyledons. The highly purified fraction contained two polypeptides, whose molecular masses were estimated to be 35 kDa and 33 kDa by SDS-PAGE. It is suggested that the 33 kDa polypeptide was a degradation product of the 35kDa polypeptide. Oleoyl-(acyl-carrier protein) was the preferred substrate of this enzyme over palmitoyl- and stearoyl-(acyl-carrier protein), whereas lauroyl-(acyl-carrier protein) was nearly inactive. These results indicate the enzyme is specific for long-chain acyl-(acyl-carrier protein).
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-5028
    Keywords: Brassica napus ; Enoyl-ACP reductase ; isoforms ; stearoyl-ACP desaturase ; developmental expression ; seed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of mRNA and the steady-state levels of two-component enzymes of plant fatty acid synthetase (FAS) were studied. Northern analysis of enoyl-ACP reductase (ER) and stearoyl-ACP desaturase (SD) gene expression showed that steady-state levels of both transcripts increase during lipid deposition in the seed reaching a maximum at 29 days after flowering (DAF). The steady-state level of ER message falls very quickly after reaching its maximum, whereas the SD message is longer-lived. The levels of these specific mRNAs in seed are 15–30 times greater than in leaf. Optimum mRNA expression precedes the maximum levels of synthesis of the two proteins, which in turn precede the maximum level of oil. The expression of isoenzymes of ER were examined by two-dimensional western blotting in both leaf and seed tissue. Four enzymes are expressed in both of these tissues; the two most abundant isoforms in seed material are also the most abundant in leaf tissue.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-5028
    Keywords: desB gene ; desaturase ; fatty acid ; Synechococcus sp. PCC 7942 ; Synechocystis sp. PCC 6803 ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cyanobacteria respond to a decrease in temperature by desaturating fatty acids of membrane lipids to compensate for the decrease in membrane fluidity. Among various desaturation reactions in cyanobacteria, the desaturation of the ω3 position of fatty acids is the most sensitive to the change in temperature. In the present study, we isolated a gene, designated desB, for the ω3 desaturase from the cyanobacterium, Synechocystis sp. PCC 6803. The desB gene encodes a protein a 359 amino-acid residues with molecular mass of 41.9 kDa. The desB gene is transcribed as a monocistronic operon that produced a single transcript of 1.4 kb. The level of the desB transcript in cells grown at 22°C was 10 times higher than that in cells grown at 34°C. In order to manipulate the fatty-acid unsaturation of membrane lipids, the desB gene in Synechocystis sp. PCC 6803 was mutated by insertion of a kanamycin-resistance gene cartridge. The resultant mutant was unable to desaturate fatty acids at the ω3 position. The desA gene, which encodes the Δ12 desaturase of Synechocystis sp. PCC 6803, and the desB gene were introduced into Synechococcus sp. PCC 7942. Whilst the parent cyanobacterium can only desaturate membrane lipids at the Δ9 position of fatty acids, the resultant transformant was able to desaturate fatty acids of membrane lipids at the Δ9, Δ12 and ω3 positions. These results confirm the function of the desB gene and demonstrate that it is possible to genetically manipulate the fatty-acid unsaturation of membrane lipids in cyanobacteria.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-5028
    Keywords: Arabidopsis ; chilling sensitivity ; glycerol-3-phosphate acyltransferase ; glycerolipid biosynthesis ; RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The gene and the RNA from Arabidopsis thaliana for the plastid-located glycerol-3-phosphate acyltransferase (GPAT; EC 2.3.1.15) and their encoded product have been studied. The gene (designated ATS1) was isolated by screening a λDASH genomic library for cross-hybridization with a radiolabeled probe prepared from cDNA for GPAT from squash. cDNA clones representing the mRNA were isolated by screening a λZAPII cDNA library for hybridization with a radiolabeled probe prepared from a DNA fragment of ATS1. The nucleotide sequences of the gene and the cDNA were determined, and the 5′ end of the RNA was mapped by primer extension. Sequences similar to the TATA box, polyadenylation sequences and intron-splicing sequences were found at the expected locations. The pre-mRNA was 3288 nucleotides long and contained 5′ and 3′-untranslated sequences of 57 and 442 nucleotides, respectively. The coding sequence of 1377 nucleotides was interrupted by 11 introns of 1412 nucleotides in total and the 3′-untranslated sequence contained another intron of 94 nucleotides. The open-reading frame encoded a polypeptide of 459 amino acid residues, the amino acid sequence of which was highly homologous to those of precursors to plastid-located GPATs from squash and pea. The enzymatic activity of a gene product that was over-produced in Escherichia coli confirmed the indentity of the gene.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-5028
    Keywords: Anabaena variabilis ; fatty-acid desaturation ; Synechococcus PCC7002 ; Synechococcus PCC7942 ; Synechocystis PCC6714 ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cyanobacterial genes for enzymes that desaturate fatty acids at the Δ12 position, designated desA, were isolated from Synechocystis PCC6714, Synechococcus PCC7002 and Anabaena variabilis by crosshybridization with a DNA probe derived from the desA gene of Synechocystis PCC6803. The genes of Synechocystis PCC6714, Synechococcus PCC7002 and A. variabilis encode proteins of 349, 347 and 350 amino acid residues, respectively. The transformation of Synechococcus PCC7942 with the desA genes from Synechocystis PCC6714, Synechococcus PCC7002 and A. variabilis was associated with the ability to introduce a second double bond at the Δ12 position of fatty acids. The amino acid sequence of the products of the desA genes revealed the presence of four conserved domains. Since one of the conserved domains was also found in the amino acid sequences of ω3 desaturases of Brassica napus and mung bean, this domain may play an essential role in the introduction of a double bond into fatty acids bound to membrane lipids.
    Type of Medium: Electronic Resource
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