Photosystem I trimers from Synechocystis PCC 6803 lacking the PsaF and PsaJ subunits bind an IsiA ring of 17 units.
We report a structural characterization by electron microscopy and image analysis of a supramolecular complex consisting of Photosystem I (PSI) and the chlorophyll-binding protein IsiA from a mutant of the cyanobacterium Synechocystis PCC 6803 lacking the PsaF and PsaJ subunits. The circular complex consists of a central PSI trimer surrounded by a ring of 17 IsiA units, one less than in the wild-type supercomplex. We conclude that PsaF and PsaJ are not obligatory for the binding of the IsiA ring, and that the size of the PSI complex determines the number of IsiA units in the ring. The resulting number of 17 copies implies that each PSI monomer has a different association to the IsiA ring.
Kouril
Roman
R
Department of Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Yeremenko
Nataliya
N
D'Haene
Sandrine
S
Yakushevska
Alevtyna E
AE
Keegstra
Wilko
W
Matthijs
Hans C P
HC
Dekker
Jan P
JP
Boekema
Egbert J
EJ
D001426:Bacterial Proteins; D003461:Crystallography / Q000379:methods*; D000458:Cyanobacteria / Q000737:chemistry* / Q000145:classification / Q000378:metabolism; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D045331:Photosystem I Protein Complex / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry / Q000172:deficiency / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013045:Species Specificity
D001426:Bacterial Proteins; D046911:Macromolecular Substances; D045331:Photosystem I Protein Complex; D021122:Protein Subunits; D011994:Recombinant Proteins; C085831:photosystem I, PsaJ subunit; C079742:psaF protein, bacteria