When we turn to the PC + Mel coated hematite (Figure 9b), the VB position shifts from 5.6 eV to 5 eV, i.e. the shift is only 0.6 eV upon illumination.
Moreover, electrogenic activity was observed upon illumination only with blue or red but not green light confirming that P-ETC is the source of electrons.
Such an allosteric signaling mechanism not only explains the absence of changes in structural dynamics of the bZIP LOV linker region upon illumination, but also explains the need for the > 30 amino acids long linker in Aureos, which is required to enable direct bZIP LOV interaction.
The T517V loop mutation in AsLOV2 showed an unaltered photocycle but increased conformational change upon illumination [ 42].
Instead, PSI core polypeptides like PsaB, which is known to be a main target of PSI core upon illumination [ 44], are more resistant to light treatment and show protein degradation only at t5 (165 min).
Only negligible light-induced differences in deuterium uptake are observed for Jα that was shown to unwind upon illumination (Herman et al., 2013) and that is also partially unstructured in the light state crystal structure.
This response depends on ChR2 activity, as flies denied ATR showed little or no response and only 10% (±10%) responded to illumination, while 93% (±12%) of flies raised with supplementary ATR showed abdominal contractions upon illumination.
The increase in structural dynamics and aggregation tendency upon illumination of most photoreceptors as well as potential photobleaching makes crystallization of photoreceptors difficult and has so far only been achieved for the single LOV domain proteins VIVID (Vaidya et al., 2011) and PpsB1 (Circolone et al., 2012) as well as for a truncated phytochrome construct (Takala et al., 2014).
Only the illumination of reason can divert us from the abyss.
So far only the illumination at the centre of an image has been considered, but the distribution of illumination over a wide field is often important.
