Interaction between photosystem I and ferredoxin. Identification by chemical cross-linking of the polypeptide which binds ferredoxin.
Ferredoxin has been effectively cross-linked to photosystem I complex by treatment of purified particles or thylakoids with N-ethyl-3-(3-dimethylaminopropyl)carbodiimide, a zero-length cross-linker which stabilizes protein-protein electrostatic interactions. Analysis of photosystem I polypeptide composition after such a treatment showed a specific decrease of the 20-kDa subunit and the appearance of a new component of about 42 kDa which was recognized by the anti-ferredoxin antibody. Cross-linking of ferredoxin to thylakoids allowed the membrane preparation to photoreduce cytochrome c without requiring exogenous ferredoxin, whereas photosystem I particles purified from treated thylakoids were inactivated in the NADP+ photoreduction activity. From these results, it can be inferred that the polypeptide of 20 kDa is the photosystem I subunit which interacts with ferredoxin during the photosynthetic electron transport.
Zanetti
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Dipartimento di Fisiologia e Biochimica Generali, Italy.
Merati
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D002234:Carbodiimides; D002736:Chloroplasts / Q000378:metabolism*; D003432:Cross-Linking Reagents; D003574:Cytochrome c Group / Q000378:metabolism; D004579:Electron Transport; D004591:Electrophoresis, Polyacrylamide Gel; D005022:Ethyldimethylaminopropyl Carbodiimide; D005288:Ferredoxins / Q000378:metabolism*; D007118:Immunoassay; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010788:Photosynthesis; D010940:Plant Proteins / Q000378:metabolism*; D010944:Plants / Q000378:metabolism
D002234:Carbodiimides; D003432:Cross-Linking Reagents; D003574:Cytochrome c Group; D005288:Ferredoxins; D010940:Plant Proteins; D009249:NADP; D005022:Ethyldimethylaminopropyl Carbodiimide