Interaction of plastocyanin with photosystem I: a chemical cross-linking study of the polypeptide that binds plastocyanin.
Plastocyanin has been covalently cross-linked to photosystem I (PSI) by using a water-soluble cross-linker, N-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. The cross-linking reaction is light stimulated and results in the disappearance of a single 19-kDa subunit of PSI with the formation of a new protein-staining component of 31 kDa. The new product at 31 kDa reacts with both plastocyanin and 19-kDa subunit antibodies. Carboxyl group modified plastocyanin does not form a cross-linked product with PSI, implying that the negatively charged surface-exposed groups on plastocyanin are necessary to stabilize binding. These results demonstrate a specific interaction of plastocyanin with PSI and further implicate a specific protein to which plastocyanin binds to facilitate electron transfer to the P700 reaction center.
Wynn
R M
RM
Division of Molecular Plant Biology, University of California, Berkeley 94720.
Malkin
R
R
D002734:Chlorophyll / Q000378:metabolism*; D003432:Cross-Linking Reagents; D004579:Electron Transport; D005022:Ethyldimethylaminopropyl Carbodiimide; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010940:Plant Proteins / Q000378:metabolism*; D010970:Plastocyanin / Q000378:metabolism*; D011485:Protein Binding
D003432:Cross-Linking Reagents; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010940:Plant Proteins; D002734:Chlorophyll; D010970:Plastocyanin; D005022:Ethyldimethylaminopropyl Carbodiimide