Abstract
Oxygen-evolving photosystem II (PSII) consists of a number of intrinsic proteins and 3-4 extrinsic proteins. The intrinsic proteins are commonly conserved from cyanobacteria to higher plants but the extrinsic proteins are different among plant species. Though the extrinsic 33 kDa protein is present in all species, the other extrinsic proteins are different among the species. Higher plant and green algal PSIIs contain the 23 and 17 kDa proteins, while cyanobacterial and red algal PSIIs associate the 12 kDa protein and cyt c550. In red algal PSII, a unique 20 kDa protein further associates. Release-reconstitution experiments also revealed that not only the types of extrinsic proteins but also their binding properties are different among the species. In this report, we discuss evolution of oxygen-evolving system in view of distribution and binding properties of the extrinsic proteins on the basis of immunoblotting analysis and release-reconstitution experiments.
