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  • 1
    Electronic Resource
    Electronic Resource
    Cold-regulated genes under control of the cold sensor Hik33 in Synechocystis (2001)
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 40 (2001), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A histidine kinase, Hik33, appears to sense decreases in temperature and to regulate the expression of certain cold-inducible genes in the cyanobacterium Synechocystis sp. PCC6803. To examine the role of Hik33 in the regulation of gene expression, we analysed a ΔHik33 mutant using the DNA microarray technique. In wild-type cells, genes that were strongly induced at low temperature encoded proteins that were predominantly subunits of the transcriptional and translational machinery. Most cold-repressible genes encoded components of the photosynthetic machinery. Mutation of the hik33 gene suppressed the expression of some of these cold-regulated genes, which could be divided into three groups according to the effect of the mutation of hik33. In the first group, regulation of gene expression by low temperature was totally abolished; in the second group, the extent of such regulation was reduced by half; and, in the third group, such regulation was totally unaffected. These results suggest that expression of the genes in the first group is regulated solely by Hik33, expression of genes in the third group is regulated by an as yet unidentified cold sensor, and expression of genes in the second group is regulated by both these cold sensors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2001.02379.x
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  • 2
    Electronic Resource
    Electronic Resource
    Differences in the control of the temperature-dependent expression of four genes for desaturases in Synechocystis sp. PCC 6803 (1997)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 25 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Cyanobacteria are capable of desaturating the fatty acids in their membrane lipids in response to decreases in temperature. The cyanobacterium, Synechocystis sp. PCC 6803, contains four desaturases, which specifically catalyse desaturation at the Δ6, Δ9, Δ12 and ω3 positions of fatty acids. The levels of the mRNAs transcribed from the genes that encode the Δ6, Δ12 and ω3 desaturases increased about 10-fold, but at different rates, upon a decrease in temperature from 34°C to 22°C, whereas the level of the mRNA for the Δ9 desaturase remained constant. The increases in the levels of mRNAs were caused both by the enhanced transcription and by the increased stability of the mRNAs at the low temperature. Western blotting analysis demonstrated that levels of the Δ6, Δ12 and ω3 desaturases increased at different rates at the low temperature, while that of the Δ9 desaturase remained constant. These observations indicate that the expression of the genes for the four desaturases is regulated by temperature in different ways.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.5641912.x
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  • 3
    Electronic Resource
    Electronic Resource
    The histidine kinase Hik33 perceives osmotic stress and cold stress in Synechocystis sp. PCC 6803 (2002)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 46 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The stress imposed on living organisms by hyperosmotic conditions and low temperature appears to be perceived via changes in the physical state of membrane lipids. We compared genome-wide patterns of transcription between wild-type Synechocystis sp. PCC 6803 and cells with a mutation in the histidine kinase Hik33 using a DNA microarray. Our results indicated that Hik33 regulated the expression of both osmostress-inducible and cold-inducible genes. The respective genes that were regulated by Hik33 under hyperosmotic and low-temperature conditions were, for the most part, different from one another. However, Hik33 also regulated the expression of a set of genes whose expression was induced both by osmotic stress and by cold stress. These results indicate that Hik33 is involved in responses to osmotic stress and low-temperature stress but that the mechanisms of the responses differ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.03202.x
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  • 4
    Electronic Resource
    Electronic Resource
    A method to probe the cytoplasmic osmolality and osmotic water and solute fluxes across the cell membrane of cyanobacteria with chlorophyll a fluorescence: Experiments with Synechococcus sp. PCC7942 (1998)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 103 (1998), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We present a method with which osmotic properties of the cytoplasm of cyanobacterial cells and the osmotic permeability of plasma membranes to water and solutes can be assessed from measurements of chlorophyll a fluorescence. When the electron transport of photosystem II is inhibited, the quantum yield of chlorophyll a fluorescence in cyanobacterial cells varied between a low yield limit that was attained after acclimation to darkness (state 2) and a high yield limit that was attained after acclimation to light (state 1). It was shown recently that the difference between chlorophyll a fluorescence of light-acclimated and of dark-acclimated cells relates quantitatively to the internal osmolality of cyanobacteria (G. C. Papageorgiou and A. Alygizaki-Zorba. 1997. Biochim. Biophys. Acta 1335: 1-4). In the present work we employed rapid mixing of Synechococcus sp. PCC7942 (strain PAMCOD) suspensions with solutions of defined osmolality in order to measure cell osmolality and turgor threshold, as well as water and solute fluxes across cell membranes. Concentration upshocks with sorbitol, glycine betaine, Na+ and K+ salts caused rapid (t1/2 〈 10 ms) depression of fluorescence that was correlated to osmotic water outflow from the cells. The fluorescence remained depressed in all cases except for NaCl. With NaCl, the depression was transient and fluorescence recovered with an apparent time constant of 200 ms. The fluorescence rise correlates to inflows of NaCl and water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1998.1030209.x
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  • 5
    Electronic Resource
    Electronic Resource
    Low-temperature resistance of higher plants is significantly enhanced by a nonspecific cyanobacterial desaturase (1996)
    [s.l.] : Nature Publishing Company
    Nature biotechnology 14 (1996), S. 1003-1006 
    Details
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] A broad-specificity Δ9 desaturase gene was cloned from the cyanobacterium Anacystis nidulans. The enzyme introduces a cis-double bond at the Δ9 position of both 16 and 18 carbon saturated fatty acids linked to many kinds of membrane lipids. The gene was stably introduced into tobacco ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nbt0896-1003
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  • 6
    Electronic Resource
    Electronic Resource
    Low-temperature-induced desaturation of fatty acids and expression of desaturase genes in the cyanobacterium Synechococcus sp. PCC 7002 (1997)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 152 (1997), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Changes in response to temperature of lipid classes, fatty acid composition and mRNA levels for acyl-lipid desaturase genes were studied in the marine unicellular cyanobacterium, Synechococcus sp. PCC 7002. The degree of unsaturation of C18 fatty acids increased in cells grown at lower temperature for all lipid classes, and ω3 desaturation occurred specifically in cells grown at low temperature. While the level of 18:1(9) fatty acids declined, desaturation at the ω3 position of C18 fatty acids increased gradually during a 12-h period after a temperature shift-down to 22°C. However, the mRNA levels of the desA (Δ12 desaturase), desB (ω3 desaturase) and desC (Δ9 desaturase) genes increased within 15 min after a temperature shift-down to 22°C; the desaturase gene mRNA levels also rapidly declined within 15 min after a temperature shift-up to 38°C. Therefore, the elevation of mRNA levels for the desaturase genes is not the rate-limiting event for the increased desaturation of membrane lipids after a temperature shift-down. The rapid, low-temperature-induced changes in mRNA levels occurred even when cells were grown under light-limiting conditions for which the growth rates at 22°C and 38°C were identical. These studies indicate that the ambient growth temperature, and not some other growth rate-related process, regulates the expression of acyl lipid desaturation in this cyanobacterium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1997.tb10445.x
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  • 7
    Electronic Resource
    Electronic Resource
    Enhancement of chilling tolerance of a cyanobacterium by genetic manipulation of fatty acid desaturation (1990)
    [s.l.] : Nature Publishing Group
    Nature 347 (1990), S. 200-203 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A mutant in fatty-acid desaturation of membrane lipids of the transformable cyanobacterium, Synechocystis PCC6803, was isolated as described previously6. This mutant, termed Fad 12, is defective in the activity of desaturation that introduces a second double bond at the A12 position of the C18 ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/347200a0
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  • 8
    Electronic Resource
    Electronic Resource
    Alteration of low-temperature susceptibility of the cyanobacterium Synechococcus sp. PCC 7002 by genetic manipulation of membrane lipid unsaturation (1997)
    Springer
    Archives of microbiology 169 (1997), S. 20-28 
    Details
    ISSN: 1432-072X
    Keywords: Key words Chilling tolerance ; Cyanobacterium ; Fatty acid desaturase ; Low-temperature acclimation ; Membrane lipid ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cyanobacteria acclimate to low temperature by desaturating their membrane lipids. Mutant strains of Synechococcus sp. PCC 7002 containing insertionally inactivated desA (Δ12 acyl-lipid desaturase) and desB (ω3 acyl-lipid desaturase) genes were produced, and their low-temperature susceptibility was characterized. The desA mutant synthesized no linoleic acid or α-linolenic acid, and the desB mutant did not produce α-linolenic acid. The desA mutant grew more slowly than the wild-type at 22° C and could not grow at 15° C. The desB mutant could not continuously grow at 15° C, although no observable phenotype appeared at higher temperatures. It has been shown that expression of the desA gene occurs at 38° C and is up-regulated at 22° C, and that the desB gene is only expressed at 22° C. These results indicate that the expression of the desA and desB genes occurs at higher temperatures than those at which a significant decline in physiological activities is caused by the absence of their products. The temperature dependency of photosynthesis was not affected by these mutations. Since chlorosis and inability to grow at 15° C with nitrate was suppressed by the substitution of urea as a nitrogen source, it is very likely that the chilling susceptibility of the desaturase mutants is attributable to nutrient limitation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050536
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  • 9
    Electronic Resource
    Electronic Resource
    Isolation and characterization of three types of membranes from the cyanobacterium (blue-green alga) Synechocystis PCC 6714 (1984)
    Springer
    Archives of microbiology 139 (1984), S. 113-116 
    Details
    ISSN: 1432-072X
    Keywords: Synechocystis PCC 6714 ; Cell wall ; Cyanobacterium ; Cytoplasmic membrane ; Thylakoid membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three types of membranes were separated from the cyanobacterium Synechocystis PCC 6714 by mechanical disruption and density gradient centrifugation. Orange-colored membranes contained xanthophylls but little β-carotene or chlorophyll a, green-colored membranes contained chlorophyll a, β-carotene and xanthophylls, and another type of orange-colored membranes contained unknown xanthophylls. These membrane preparations were similar to those from Anacystis nidulans in pigmentation and buoyant density and were identified as purified preparations of the cytoplasmic membranes, thylakoid membranes and cell walls of Synechocystis PCC 6714, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00401984
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  • 10
    Electronic Resource
    Electronic Resource
    Heat shock protein synthesis of the cyanobacterium Synechocystis PCC 6803: purification of the GroEL-related chaperonin (1992)
    Springer
    Plant molecular biology 18 (1992), S. 327-336 
    Details
    ISSN: 1573-5028
    Keywords: chaperonin ; heat shock protein (HSP) ; HSP70 ; HSP64 ; Rubisco-binding protein ; Synechocystis PCC 6803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Synechocystis PCC 6803 cells could be induced to synthesize four major HSPs with apparent molecular sizes of 70, 64, 15 and 14 kDa. Heat stress at 42.5 °C appeared to be the optimum temperature for HSP formation in cells grown at 30 °C. The relative rate of synthesis of HSP70 and HSP15 reached a maximum at 30 min after the temperature shift-up whereas the capability of cells to accumulate HSP64 and HSP14 continued through 2 h. The two most abundant HSPs, HSP70 and HSP64, were recognized on western blots by antibodies raised against authentic DnaK and GroEL from Escherichia coli. To furnish sufficient evidence for the assumption that HSP64 is a GroEL-related chaperonin, this protein was purified to homogeneity. There was a 76% sequence identity between the amino acid sequence of HSP64 and the corresponding protein in Synechococcus PCC 7942. Moreover, the purified HSP64 cross-reacted to anti-E. coli GroEL antibody. To our knowledge, this is the first report about the purification and partial protein sequencing of a cyanobacterial chaperonin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034959
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