Design principles of solar light harvesting in plants: Functional architecture of the monomeric antenna CP29

Identification of parallel pH- and zeaxanthin-dependent quenching of excess energy in LHCSR3 in Chlamydomonas reinhardtii

“…The Chl a have the lowest energy levels, which are the emissive states that give rise to each component. The existence of three components indicates multiple Chl a emissive sites within LHCSR3, consistent with previous models of LHCs (Mascoli et al 2019, Mascoli et al 2020, Krüger et al 2010, Krüger et al 2011. The two dynamic components arise from changes in the extent of quenching of the Chl emitters.…”

Light-harvesting complexes access analogue emissive states in different environments

“…The model has a CP29 complex as its smallest unit, whereas intra-monomer energy equilibration is neglected being about an order of magnitude faster than the experimental time resolution. 47 – 49 At RT, each CP29 complex in the aggregate can be found in one of three possible states: blue unquenched, blue quenched, or FR. At 77 K, four emissive states are possible: blue unquenched, blue quenched, intermediate, and FR ( Fig.…”

“…1 ), 41 are involved in the low energy states of the complex. 42 , 49 As a result, these two Chls can be expected to play a role in the quenching mechanism and/or in the occurrence of red forms. In addition, we have recently demonstrated that, at RT, only the loss of Chl a 612 has a significant effect on quenching in the monomers, as the occurrence of short-lived complexes decreases and their decay rate is slowed down 22 (see Fig.…”

“…This difference in flexibility might be a consequence of the different pigment content of LHCII, whose low energy states are concentrated on Chls a 610– a 611– a 612 only (as in CP29 KO603), whereas in WT CP29 there are more low-energy Chls. 49 …”

“…This difference in exibility might be a consequence of the different pigment content of LHCII, whose low energy states are concentrated on Chls a610-a611-a612 only (as in CP29 KO603), whereas in WT CP29 there are more low-energy Chls. 49 The mutants also display a lower extent of red-shied emission upon clustering. Notably, this feature seems not to correlate with the amount of quenching, as the KO603 oligomers are the most quenched and, at the same time, emit signicantly less long-wavelength photons than the WT ones.…”