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  • Cyanobacteria  (5)
  • Springer  (5)
  • Public Library of Science (PLoS)
  • 1
    Electronic Resource
    Electronic Resource
    Structure and mutation of a gene encoding a Mr 33000 phycocyanin-associated linker polypeptide (1990)
    Springer
    Archives of microbiology 153 (1990), S. 541-549 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Synechococcus sp. PCC 7002 ; Agmenellum quadruplicatum ; Phycobilisome ; Phycocyanin ; Linker polypeptide ; Photosynthetic antenna ; Nucleotide sequence ; Directed mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The gene encoding a phycocyanin-associated linker polypeptide of Mr 33000 from the cyanobacterium Synechococcus sp. PCC 7002 was found to be located adjacent and 3′ to the genes encoding the α and β subunits of phycocyanin. The identity of this gene, designated cpcC, was proven by matching the amino-terminal sequence of the authentic polypeptide with that predicted by the nucleotide sequence. A cpcC mutant strain of this cyanobacterium was constructed. The effect of the mutation was to prevent assembly of half the total phycocyanin into phycobilisomes. By electron microscopy, phycobilisomes from this mutant were shown to contain rod substructures composed of a single disc of hexameric phycocyanin, as opposed to two discs in the wild type. It was concluded that the Mr 33000 linker polypeptide is required for attachment of the core-distal phycocyanin hexamer to the core-proximal one. Using absorption spectra of the wild type, CpcC−, and phycocyanin-less phycobilisomes, the in situ absorbances expected for specific phycocyanin-linker complexes were calculated. These data confirm earlier findings on isolated complexes regarding the influence of linkers on the spectroscopic properties of phycocyanin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00245263
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  • 2
    Electronic Resource
    Electronic Resource
    The structure of Gloeobacter violaceus and its phycobilisomes (1981)
    Springer
    Archives of microbiology 129 (1981), S. 181-189 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Gloeobacter violaceus ; Synechocystis ; Freeze-etching ; Membranes ; Phycobilisomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fine structure of the atypical cyanobacterium Gloeobacter violaceus has been studied on frozen-etched replicas and compared to that of a typical unicellular strain: Synechocystis 6701. The complementary fracture faces of G. violaceus cytoplasmic membrane contain particles less numerous and more heterogenous in size than either the cytoplasmic membrane or the thylakoid membranes of Synechocystis. The most frequently observed particles of the exoplasmic fracture (EF) face of the G. violaceus cytoplasmic membrane are 11 nm in diameter and occasionally form short alignments. This particle class is similar in appearance to the numerous, aligned EF particles of Synechocystis thylakoid membranes. In replicas of cross-fractured G. violaceus, a layer 50–70 nm thick, composed of rod-like elements, underlies the inner surface of the cytoplasmic membrane. The rods, 12–14 nm in diameter, are oriented perpendicularly to the cytoplasmic membrane and show a 6 nm repeat along their length. Isolated phycobilisomes of G. violaceus appear, after fixation and negative staining, as bundles of 6 parallel rodshaped elements connected to an ill-defined basal structure. The bundles are 40–45 nm wide and 75–90 nm long. The rods are 10–12 nm in width; their length varies between 50 and 70 nm. These rods are morphologically similar to those observed at the periphery of hemidiscoidal phycobilisomes of other cyanobacteria, with a strong repeat at 6 nm intervals and a weaker one at 3 nm intervals along their length. The calculated molar ratio of phycobiliproteins in isolated G. violaceus phycobilisomes corresponds to 1:3.9:2.9 for allophycocyanin, phycocyanin and phycoerythrin respectively. When excited at 500 nm, isolated phycobilisomes exhibit a major fluorescence emission band centered at 663 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425248
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  • 3
    Electronic Resource
    Electronic Resource
    Cloning and expression of a Nostoc sp. leucine biosynthetic gene in Escherichia coli (1986)
    Springer
    Archives of microbiology 145 (1986), S. 315-321 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; DNA restriction and cloning ; Gene fusions ; Leucine biosynthesis ; Mutant complementation ; Nostoc ; Transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genomic DNA extracted from the symbiotically-competent, heterocyst-forming cyanobacterium Nostoc sp. strain 7801 was resistant to cleavage by a number of restriction endonucleases. A cosmid library of Nostoc DNA was prepared and maintained in the modification-limited Escherichia coli strain HB101. Analysis of cloned Nostoc DNA fragments indicated infrequent occurrence of restriction endonuclease recognition sites in the Nostoc genome. The Nostoc genomic library was screened for sequences complementing mutations in the E. coli leucine and proline biosynthetic operons. Two cosmids complementing leuB were isolated but none for leuA, leuC, leuD, or proA were detected in 1000 cosmids. A 3.0 kb fragment subcloned from one of the cosmids complemented mutations in leuB when inserted into the HindIII site of pBR322 in either orientation, demonstrating that transcription of leuB originated within the cloned fragment. The cloned fragment also carries a second site capable of initiating transcription of fused antibiotic resistance genes. While transcription of Nostoc DNA sequences did occur in E. coli, unknown barriers must also exist that prevented additional biological complementation of specific E. coli mutations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00470864
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  • 4
    Electronic Resource
    Electronic Resource
    The structure of cyanobacterial phycobilisomes: a model (1979)
    Springer
    Archives of microbiology 123 (1979), S. 113-127 
    Details
    ISSN: 1432-072X
    Keywords: Phycobilisomes ; Phycobiliproteins ; Cyanobacteria ; Chromatic adaptation ; Fine structure ; Photosynthesis ; Protein assembly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phycobilisomes, supramolecular complexes of water-soluble accessory pigments, serve as the major light-harvesting antennae in cyanobacteria and red algae. Regular arrays of these organelles are found on the surface of the thylakoid membranes of these organisms. In the present study, the hemi-discoidal phycobilisomes of several species of cyanobacteria were examined in thin sections of cells and by negative staining after isolation and fixation. Their fundamental structures were found to be the same. Isolated phycobilisomes possessed a triangular core assembled from three stacks of disc-shaped subunits. Each stack contained two discs which were ∼12 nm in diameter and ∼6–7 nm thick. Each of these discs was probably subdivided into halves ∼3–3.5 nm thick. Radiating from each of two sides of the triangular core were three rods ∼12 nm in diameter. Each rod consisted of stacks of 2 to 6 disc-shaped subunits ∼6 nm thick. These discs were subdivided into halves ∼3 nm thick. The average number of discs of ∼6 nm thickness forming the peripheral rods varied among the strains studied. For certain chromatically adapting strains, the average rod length was dependent upon the wavelength of light to which cells were exposed during growth. Analyses of phycobilisomes by spectroscopic techniques, polyacrylamide gel electrophoresis, and electron microscopy were compared. These analyses suggested that the triangular core was composed of allophycocyanin and that the peripheral rods contained phycocyanin and phycoerythrin (when present). A detailed model of the hemi-discoidal phycobilisome is proposed. This model can account for many aspects of phycobiliprotein assembly and energy transfer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446810
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  • 5
    Electronic Resource
    Electronic Resource
    Isolation and characterization of Anacystis nidulans R2 mutants affected in nitrate assimilation: Establishment of two new mutant types (1988)
    Springer
    Molecular genetics and genomics 213 (1988), S. 223-228 
    Details
    ISSN: 1617-4623
    Keywords: Cyanobacteria ; Nitrate reductase mutants ; Nitrite reductase mutants ; Regulatory mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Eighteen mutant strains of the unicellular cyanobacterium Anacystis nidulans R2 that are unable to assimilate nitrate have been isolated after transposon Tn901 mutagenesis. Characterization of phenotypes and transformation tests have allowed the distinction of five different mutant types. The mutants exhibiting a nitrate reductase-less phenotype were identified as being affected in previously defined loci, as they could be transformed to the wild type by one of the plasmids pNR12, pNR63 or pNR193, which contain cloned genes of A. nidulans R2 involved in nitrate reduction. The mutations in strains FM2 and FM16 appear to affect two other genes involved in nitrate assimilation. Strain FM2 apparently bears a single mutation which results in both lack of nitrite reductase activity and loss of ammonium-promoted repression of nitrate reductase synthesis. FM16 has a low but significant level of nitrate reductase that is also freed from repression by ammonium, and an increased level of nitrite reductase activity. FM16 exhibited properties which indicate that this mutant strain might also be affected in the transport of nitrate into the cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00339585
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