Abstract
Photosystem I is a chlorophyll protein complex, which is consist of 14 subunits and mediates the electron transfer from plastocyanin to ferredoxin. PsaL is one of the peripheral subunits of photosystem I and has been proposed to be involved in state transitions in plants. However, the detail of its role in state transitions remains elusive. In the present study, we generated knock down transformants of PsaL by using RNAi technique from the green alga Chlamydomonas reinhardtii. After screening of 230 paromomycin-resistant transformants, we obtained 3 lines of transformant in which the accumulation of PsaL protein decreased to <3% of that in cw-15, the host strain. Western analyses for PSI proteins showed that, in the PsaL-RNAi strains, the accumulation of PSI proteins was not affected except for PsaH, which decreased to approximately 10% of that in cw-15. We are now analyzing the state transitions of these transformants by means of low temperature fluorescence spectra and will discuss the role of PsaL on the association of minor LHCII proteins with photosystem I.
