The cells grown under 50 µmol photons m−2 s−1 at HC and LC were illuminated in a photobioreactor at 1500 µmol photons m−2 s−1 white light for up to 90 min, and the PSII activity was measured during the course of illumination by monitoring the oxygen evolving activity of the cells.
In search for the role of the FtsH protease we studied the UV-B induced damage in the oxygen evolving activity of PSII in the MFtsH mutant from which the slr0228 gene had deleted.
About 10% decrease in the photochemical efficiency (Fv/Fm) and the oxygen evolving activity of photosystem II (PSII) was measured after cold and light (hereafter, Cold/Light or C/L) treatment, but not after cold and dark (hereafter Cold/Dark or C/D) treatment (Table 1).
Under LC, both Δflv2 and Δflv4 cells lost more of the PSII oxygen evolving activity during the high light illumination than WT (Figure 7).
The high oxygen evolving activity can be attributed to the mesoporous one-dimensional nanostructure with abundant surface electrochemically active sites and improved electric conductivity, thus facilitating the charge/electron transfer and further improving the efficiency of water electrolysis.
The mechanism behind the enhancement in the oxygen-evolving activity is proposed on the basis of in-situ electron spin resonance (ESR) measurement as well as theoretical analysis.
These observations may suggest that exposure of Synechocystis cells to strong light results in the irreversible photoinhibition of the oxygen-evolving activity of PSII via impairment of the processing of pre-D1 and that this effect of strong light is enhanced by the rigidification of membrane lipids.
After 90 min treatment, more than 80% of PSII oxygen evolving activity still remained in the WT, but only about 60% of PSII activity was left in Δflv2 and Δflv4.
We have used this simulation to study the time frequency properties of the evolving bursting activity, as well as effects due to network stimulation.
However, some investigators dispute that energy expenditure requirements have decreased [ 42, 43] which casts questions on the potential role that energy expenditure played in evolving activity regulation.
The last three amino acid residues, including leucin at position 246 (245 in spinach), were shown to be critical for binding to PSII and for restoration of oxygen evolving activity [ 47].
