Supramolecular organization of photosystem I and light‐harvesting complex I in Chlamydomonas reinhardtii

Abstract
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.