Functional analysis of PSII-T protein of Photosystem II complex from the thermophilic cyanobacterium, Thermosynechococcus (formerly Synechococcus) elongatus BP-1

摘要

PSII is a multi-subunit pigment-protein complex with the enzymatic activity of lightdependent water-oxidizing plastoquinone reductase. The PSII complex has been shown to be in a dimeric form in thylakoid membranes of both cyanobacteria and plants, although its precise role has not yet been established (Nield et al. 2000). Possible involvment of PSII-W in dimerization was reported in the antisense mutant of Arabidopsis (Shi et al. 2000). However, this subunit is absent in the cyanobacterial genome, in spite of the dimeric form. In this report, we cloned and disrupted psbT in the thermophilic Thermosynechococcus elongatus BP-1 and isolated the active PSII complex. Results suggested that psbT is dispensable for the photoautotrophic growth but is necessary for dimerization of the complex.