Abstract
We found out that disruptant of slr1212 encoding a phytochrome-related protein reduced the accumulation of carotenoid after irradiation of 300 to 500 μmol m-2s-1 for twelve hours. The accumulation of carotenoid was effectively induced by irradiation of orange (615nm) and violet (395nm) of high light in the wild type and was reduced under both light conditions in slr1212 disruptant. Furthermore, longer irradiation of violet light led to cell bleaching.
In this cyanobacterial genome, response regulator gene slr1213 encoding AraC subfamily is adjacent to slr1212 suggesting that it may function as a transcription factor in the downstream of Slr1212. Inactivation of slr1213 in the slr1212 disruptant restored the carotenoid accumulation. This suggests that Slr1213 functions as a repressor of carotenoid accumulation and Slr1212 represses the activity of Slr1213. Analysis in the composition of cellular carotenoid demonstrated that the accumulation of myxol-DF was reduced in slr1212 disruptant.
