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  • Chloroplast biogenesis  (2)
  • ATPase (plastid envelope)  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Origin and developmental changes of envelope proteins and translocator activities from plastids of Secale cereale L. (1985)
    Springer
    Planta 166 (1985), S. 452-465 
    Details
    ISSN: 1432-2048
    Keywords: Adenylate kinase ; ATPase (plastid envelope) ; Phosphate translocator ; Plastid envelope ; Protein synthesis (plastid) ; Secale (plastid envelope) ; Translocator (dicarboxylate, phosphate)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To determine the sites of synthesis of chloroplast-envelope proteins, we have analysed several enzyme and translocator functions ascribed to the envelope membranes, and investigated the envelope polypeptide composition of plastids isolated from 70S ribosome-deficient leaves of rye (Secale cereale L.) generated by growing the plants at a temperature of 32°C. Since the ribosomedeficient plastids are also achlorophyllous in light-grown leaves, not only were chloroplasts from mature, green leaves used for comparison, but also those from yellowing, aged leaves as well as etioplasts from dark-grown leaves raised at a temperature of 22° C. A majority of the plastidenvelope polypeptides appeared to be of cytoplasmic origin. The envelopes of ribosome-deficient plastids possessed ATPase (EC 3.6.1.3) activity; this was not, however, dependent on divalent cations, in contrast to the Mn2+- or Mg2+-dependent ATPase which is associated with chloroplast envelopes. Adenylate kinase (EC 2.7.4.3) was present in the stromal fraction of ribosome-deficient plastids and the stromal form of this enzyme is, therefore, of cytoplasmic origin. In contrast to previous findings, adenylate kinase was not, however, specifically associated with the chloroplast-envelope membranes, either in rye or in spinach. Measurements of the uptake of l-[14C]-malate into ribosome-deficient plastids indicated the presence and cytoplasmic origin of the dicarboxylate translocator. Malate uptake into rye etioplasts was, however, low. The phosphate translocator was assayed by the uptake of 3-phospho-[14C]glycerate. While rapid 3-phosphoglycerate uptake was observed for rye chloroplasts and etioplasts, it was hardly detectable for ribosome-deficient, plastids and rather low for chloroplasts from aged leaves. A polypeptide of M r approx. 30000 ascribed to the phosphate translocator was greatly reduced in the envelope patterns of ribosome-deficient plastids and of chloroplasts from aged leaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391269
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  • 2
    Electronic Resource
    Electronic Resource
    Capacity for chlorophyll synthesis in heat-bleached 70S ribosome-deficient rye leaves (1977)
    Springer
    Planta 135 (1977), S. 83-88 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll ; Chloroplast biogenesis ; High-temperature sensitivity ; Plastid ribosomes ; Ribosomes ; Secale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The leaves of young rye plants (Secale cereale L.) grown at 32° were deficient in chlorophyll and in chloroplastic rRNA as compared to those grown at 22°, which developed normally. Both chlorophyll accumulation and the formation of plastidic rRNA were largely restored at 32° when the plants were transfered several times for 1 h per day to 22°. In the chlorotic 32°-grown rye leaves the in vivo activity of δ-aminolevulinate synthetase was very low. Aminolevulinate dehydratase however, exhibited high activity in extracts from 32°-grown leaves and was localized in the plastid fraction isolated from the chlorotic leaf tissue. After application of δ-aminolevulinic acid to chlorotic parts of leaves growing at 32°, protochlorophyll(ide) was formed and accumulated in the dark. In the light, the protochlorophyll(ide) was photooxidized at 32°. The results suggest a cytoplasmic site of synthesis for the series of enzymes converting δ-aminolevulinate to protochlorophyll(ide). It is concluded that an inhibition of δ-aminolevulinate synthetase and the photooxidation of protochlorophyll(ide) or chlorophyll are responsible for the chlorosis of the leaves at 32°.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387980
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  • 3
    Electronic Resource
    Electronic Resource
    Comparative analysis of the action of cytokinin and light on the formation of ribulosebisphosphate carboxylase and plastid biogenesis (1978)
    Springer
    Planta 142 (1978), S. 75-82 
    Details
    ISSN: 1432-2048
    Keywords: Chloroplast biogenesis ; Cytokinins ; Enzyme development ; Photoregulation ; Ribulose-1,5-bisphosphate carboxylase ; Secale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role of cytokinin in plastid biogenesis was investigated in etiolated rye leaves (Secale cereale L.) and compared with the effect of white light. Cytokinin deficiency of the leaves was induced by early excision of the seedling roots and reversed by the application of kinetin. The cytokinin supply had a much greater influence on plastid biogenesis than on leaf growth in general. The activities of several chloroplastic enzymes were increased 200%–400% after kinetin treatment of cytokinin-depleted leaves. The activity of ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39) and the amount of fraction-I protein even showed a sevenfold increase. In cytokinin-depleted leaves the development of ribulose-1,5-bisphosphate carboxylase and NADP-glyceraldehydephosphate dehydrogenase was specifically, and markedly inhibited by actinomycin D. The inhibition was partially or even completely overcome after treatment with kinetin. However, under all conditions, RNA synthesis of the leaves, was only partially inhibited by actinomycin D. According to immunologic studies, all dark-grown leaves, in addition to the complete enzyme, contained an excess of free small subunit of ribulose-1,5-bisphosphate carboxylase that was absent in mature light-grown leaves. The most striking accumulation of free small subunit, protein occurred in cytokinin-depleted dark-grown leaves, indicating a deficiency of the plastidic synthesis of the large subunit. The capacity as well as the activity of plastidic protein synthesis was preferentially increased by cytokinin and light. Cytokinin increased, the amount of plastidic ribosomes per leaf and relative to the amount of cytoplasmic ribosomes. While the percentage of cytoplasmic ribosomes bound as polyribosomes was little affected by the cytokinin supply, the proportion of plastidic polyribosomes was increased from 11% to 18% after kinetin treatment of cytokinin-depleted leaves. In the light, the proportion of plastidic polyribosomes reached 39% of the total plastidic ribosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385123
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