PS I to PS II ratio the whole cells of WT and the RpaA mutant.

WT and mutant cells were grown in LL and then transferred to HL for 24 h. Whole cells were analyzed by fluorescence emission spectroscopy at 77 K with an excitation wavelength of 430 nm. Spectrum were recorded at three different time points, first before the cells were transferred to HL then 12 h and 24 h post transfer to HL respectively. The ratio of the fluorescence intensity originated from PS I (720 nm) and PSII (685 nm) was used as an estimate of PS I to PS II ratio. Data were generated by averaging three independent experiments on different days.