Supramolecular organization of photosystem I and light-harvesting complex I in Chlamydomonas reinhardtii.
We report a structural characterization by electron microscopy and image analysis of a supramolecular complex consisting of photosystem I and light-harvesting complex I from the unicellular green alga Chlamydomonas reinhardtii. The complex is a monomer, has longest dimensions of 21.3 and 18.2 nm in projection, and is significantly larger than the corresponding complex in spinach. Comparison with photosystem I complexes from other organisms suggests that the complex contains about 14 light-harvesting proteins, two or three of which bind at the side of the PSI-H subunit. We suggest that special light-harvesting I proteins play a role in the binding of phosphorylated light-harvesting complex II in state 2.
Germano
Marta
M
Faculty of Sciences, Department of Physics and Astronomy, Vrije Universiteit, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands.
Yakushevska
Alevtyna E
AE
Keegstra
Wilko
W
van Gorkom
Hans J
HJ
Dekker
Jan P
JP
Boekema
Egbert J
EJ
D000818:Animals; D002499:Centrifugation, Density Gradient; D016825:Chlamydomonas reinhardtii / Q000737:chemistry / Q000648:ultrastructure*; D000458:Cyanobacteria / Q000737:chemistry / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D007091:Image Processing, Computer-Assisted; D046911:Macromolecular Substances; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000648:ultrastructure*; D045331:Photosystem I Protein Complex; D010940:Plant Proteins / Q000737:chemistry; D018724:Spinacia oleracea / Q000737:chemistry / Q000648:ultrastructure; D020524:Thylakoids / Q000737:chemistry / Q000648:ultrastructure
D046911:Macromolecular Substances; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010940:Plant Proteins