Rapid and discrete isolation of oxygen-evolving His-tagged photosystem II core complex from Chlamydomonas reinhardtii...

We have developed a simple and rapid procedure to isolate an oxygen-evolving photosystem II (PS II) core complex from Chlamydomonas reinhardtii. A His-tag made of six consecutive histidine residues was genetically attached at the carboxy terminus of D2 protein to create a metal binding site on the PS II supramolecular complex. The recombinant cells producing the His-tagged variant of D2 protein grew photoautotrophically as well as the wild-type cells. Characterization of the oxygen evolution and the thermoluminescence properties revealed that the His-tagging did not affect the functional integrity of the PS II reaction center. A PS II core complex was isolated from the detergent-solubilized thylakoids of the recombinant cells in 4 h by a single one-step Ni2+ affinity column chromatography. This preparation consists of D1, D2, CP43, CP47, 33 kDa, and a few low molecular weight proteins, and retains a high rate of oxygen-evolving activity (= 1000 micromol/mg Chl/h).