Cross-reconstitution of the extrinsic proteins and photosystem II complexes from Chlamydomonas reinhardtii and Spinacia oleracea.

Cross-reconstitution of the extrinsic proteins and Photosystem II (PS II) from a green alga, Chlamydomonas reinhardtii, and a higher plant,Spinacia oleracea, was performed to clarify the differences of binding properties of the extrinsic proteins between these two species of organisms. (1) Chlamydomonas PsbP and PsbQ directly bound to Chlamydomonas PS II independent of the other extrinsic proteins but not to spinach PS II. (2) Chlamydomonas PsbP and PsbQ directly bound to the functional sites of Chlamydomonas PS II independent of the origins of PsbO, while spinach PsbP and PsbQ only bound to non-functional sites on Chlamydomonas PS II. (3) Both Chlamydomonas PsbP and spinach PsbP functionally bound to spinach PS II in the presence of spinach PsbO. (4) While Chlamydomonas PsbP functionally bound to spinach PS II in the presence of Chlamydomonas PsbO, spinach PsbP bound loosely to spinach PS II in the presence of Chlamydomonas PsbO with no concomitant restoration of oxygen evolution. (5) Chlamydomonas PsbQ bound to spinach PS II in the presence of Chlamydomonas PsbP and PsbO or spinach PsbO but not to spinach PS II in the presence of spinach PsbP and Chlamydomonas PsbO or spinach PsbO. (6) Spinach PsbQ did not bind to spinach PS II in the presence of Chlamydomonas PsbO and PsbP. On the basis of these results, we showed a simplified scheme for binding patterns of the green algal and higher plant extrinsic proteins with respective PS II.