Abstract
We generated Synechocystis sp. PCC6803 strains, which express His-tagged PsaF and PsaJ subunits, for simple and rapid purification of PSI complex. In the generated strains, F-His and J-His, the C-terminus of PsaF and the N-terminus of PsaJ were tagged with 6 histidine residues. Growth profile of F-His and J-His cells under photoautotrophic condition was similar to that of wild type. No difference in photosynthetic activity was also observed among wild-type, F-His and J-His cells. PSI complexes could be simply purified from the F-His and J-His cells by solubilization of thylakoid membranes with dodecylmaltoside followed by a Ni2+ affinity column chromatography. The purified PSI complexes were separated to monomer and trimer by ultracentrifugation with glycerol density gradient. Blue-Native PAGE and SDS-PAGE analyses of the purified PSI complexes indicated the existence of two distinct monomers having different subunit composition.
