title: Interaction between photosystem I and flavodoxin from the cyanobacterium Synechococcus sp. PCC 7002 as revealed by chemical cross-linking.
abstract: The interaction between photosystem I (PS I) and flavodoxin from the cyanobacterium Synechococcus sp. PCC 7002 was investigated by covalent cross-linking in the presence of a hydrophilic cross-linker, N- ethyl-3-(3-diaminopropyl)carbodiimide. Under the experimental conditions employed, five distinct cross-linking products of flavodoxin and PS I subunits are formed. Immunoblot analyses show that these species are the result of cross-linking of flavodoxin to PsaC, PsaD, an unidentified low-molecular-mass PS I polypeptide, and a 15-kDa subunit. The latter has been indirectly identified as the PsaF subunit. Analysis of the interaction of flavodoxin with PS I from a psaE mutant indicates that the PsaE subunit is required for correct complex formation between flavodoxin and PS I, although this subunit is not directly cross-linked to flavodoxin. In addition, the cross-linking products of PsaD with PsaC and PsaL, and PsaE with PsaF, are observed. The covalent complex of flavodoxin and PS I is shown to be fully inhibited with respect to electron transfer to soluble flavodoxin, ferredoxin or ferredoxin:NADP+ oxidoreductase.
authors.affiliation: Department of Biochemistry and Molecular Biology, The Pennsylvania State University, USA.
authors.forename: U
authors.initials: U
authors.lastname: Mühlenhoff
authors.forename: J
authors.initials: J
authors.lastname: Zhao
authors.forename: D A
authors.initials: DA
authors.lastname: Bryant
mesh_terms: D001665:Binding Sites; D003432:Cross-Linking Reagents; D000458:Cyanobacteria / Q000235:genetics / Q000378:metabolism*; D005288:Ferredoxins / Q000737:chemistry; D005418:Flavodoxin / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins; D008970:Molecular Weight; D009154:Mutation; D010084:Oxidation-Reduction; D010777:Photochemistry; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D045331:Photosystem I Protein Complex; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D003432:Cross-Linking Reagents; D005288:Ferredoxins; D005418:Flavodoxin; D008565:Membrane Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010940:Plant Proteins; D011506:Proteins; C070290:PsaD protein, cyanobacteria; C089909:photosystem I, psaB subunit; C079741:photosystem I, psaE subunit