Isolation and Characterization of cDNA Clones Encoding Five Subunits of Photosystem I from the Green Alga Chlamydomonas reinhardtii

The Photosystem I (PS I) reaction-centre is a multisubunit complex consisting of two large subunits (80–85 kDa) and several smaller subunits (3–25 kDa). The two large subunits which bind the reaction-centre pigments and an 8–9 kDa iron-sulphur protein are encoded by the chloroplast genome while the other subunits appear to be nuclear-encoded. In the unicellular green alga Chlamydomonas reinhardtii six nuclear-encoded subunits of PS I have been identified [1]: the C. reinhardtii thylakoid polypeptides number 20, 21, 28, 30, 35 and 37 (apparent molecular masses in SDS-PAGE 18, 18, 13, 11, 5 and 3 kDa, respectively). Here we present the analysis of cDNA clones encoding polypeptides 21, 28, 30, 35 and 37 (P21, P28, P30, P35 and P37, respectively). The nucleotide sequences will appear in the EMBL, GenBank and DDBJ Databases under the accession numbers X13495 (P21), X15164 (P28), X13496 (P30), X15165 (P35) and X15166 (P37).