Reconstitution of electron transport by cytochrome c-553 in a cell-free system of Nostoc muscorum |
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Authors: | Erwin Stürzl Siegfried Scherer Peter Böger |
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Affiliation: | (1) Lehrstuhl für Physiologie und Biochemic der Pflanzon, Universität Konstanz, D-7750 Konstanz, Germany |
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Abstract: | Treatment of spheroplasts of Nostoc museorum with hypotonic buffer results in membranes depleted of cytochrome c-553, but still active in photosynthetic and respiratory electron transport. These membranes retain full photosystem II activity (H2ODADox). Complete linear electron transport (H2ONADP+), however, is decreased as compared with untreated spheroplasts. Addition of basic Nostoc cytochrome c-553 to depleted membranes reconstitutes NADP+ reduction and redox reactions of the photosystem I region as well.Using NADPH as electron donor, respiration of depleted membranes is also stimulated by adding cytochrome c-553, indicative of its function in respiratory electron transport.Cytochrome c-553 from Bumilleriopsis filiformis, Spirulina platensis (acidic types), Phormidium foveolarum (basic type), and mitochondrial horse-heart cytochrome c-550 are not effective in reconstituting both photosynthetic and respiratory electron transport, which points to a specific role of Nostoc cytochrome c-553.Abbreviations BSA bovine serum albumin - DAD 3,6-diaminodurene - DADox 3,6-diaminodurene oxidized by potassium ferricyanide - DBMIB 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - DCIP 2,6-dichlorophenolindophenol - DPC 1,5-diphenylcarbazide - Fd ferredoxin - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - MES 2(-N-morpholino)-ethanesulfonic acid - MV methylviologen (1,1-dimethyl-4,4-bipyridylium dichloride) - PS I photosystem I - PS II photosystem II - Tris tris-(hydroxymethyl)-aminomethane |
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Keywords: | cytochrome c-553 dual cytochrome function Nostoc muscorum photosynthetic and respiratory electron transport spheroplasts thylakoids |
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