On insertion of pigment-associated polypeptides during membrane biogenesis in Rhodopseudomonas capsulata |
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Authors: | Roland Dierstein Arne Schumacher Gerhart Drews |
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Affiliation: | (1) Lehrstuhl für Mikrobiologie, Institut für Biologie 2 der Universität, Schänzlestr. 1, D-7800 Freiburg i. Br., Federal Republic of Germany |
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Abstract: | Early stages in the formation of membranes and photosynthetic units were studied under growth-limiting phototrophic and chemotrophic conditions in cells of Rhodopseudomonas capsulata. The incorporation of polypeptides, forming bacteriochlorophyll-carotinoid-protein complexes in the membrane, was followed by use of pulse-labeling and immunoprecipitation techniques. The newly synthesized polypeptides were inserted into two distinct membrane fractions at both different rates and proportions. The two membrane fractions differed in sedimentation behavior, absorption spectra and activities of the respiratory chain. The individual pigment-associated proteins did not exhibit precursor-product relationship between the two membrane fractions. The data suggest that newly synthesized polypeptides were integrated both into cytoplasmic and pre-existing intracytoplasmic membranes, where the proteins and pigments were assembled to form reaction centers and light-harvesting pigment-protein complexes.Abbreviations Bchl bacteriochlorophyll - cpm counts per minute - Mr relative molecular mass - P 100 pellet of 100,000xg, 60 min - P300 pellet of 300,000xg, 90 min - pO2 oxygen partial pressure - R Rhodopseudomonas - dodecyl sulfate sodium dodecyl sulfate. International standard units - Bq Becquerel (s-1) - Pa Pascal (N/m2; 1 Torr=133,3 Pa) |
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Keywords: | Bacteriochlorophyll a Associated polypeptides Rhodopseudomonas capsulata Membrane differentiation Photosynthetic apparatus |
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