Abstract
Psb30 (Ycf12) is a novel hydrophobic subunit of photosystem II (PSII) complex first reported in Thermosynechococcus elongatus (Kashino et al. BBA 2007). In Chlamydomonas, this polypeptide is encoded by the chloroplast gene psb30 (ycf12). We have generated psb30-deficient transformants (Δpsb30) by chloroplast transformation. The transformants grew photosynthetically, indicating that Psb30 is not essential for PSII activity. We are currently testing the growth of these transformants under various stress conditions. We also raised a specific antibody against synthetic oligopeptide of Psb30. It was confirmed that Psb30 accumulates on thylakoid membranes and its level was significantly reduced in various PSII-deficient mutants. In addition, fractionation of thylakoid extracts by sucrose density gradient ultracentrifugation and ion exchange chromatography revealed that Psb30 is co-purified with PSII core complex. We are trying to locate Psb30 in PSII core complex by partial dissociation of the core complex.
