Controlled disorder in plant light-harvesting complex II explains its photoprotective role.
The light-harvesting antenna of photosystem II (PSII) has the ability to switch rapidly between a state of efficient light use and one in which excess excitation energy is harmlessly dissipated as heat, a process known as qE. We investigated the single-molecule fluorescence intermittency of the main component of the PSII antenna (LHCII) under conditions that mimic efficient use of light or qE, and we demonstrate that weakly fluorescing states are stabilized under qE conditions. Thus, we propose that qE is explained by biological control over the intrinsic dynamic disorder in the complex-the frequencies of switching establish whether the population of complexes is unquenched or quenched. Furthermore, the quenched states were accompanied by two distinct spectral signatures, suggesting more than one mechanism for energy dissipation in LHCII.
Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, De Boelelaan, Amsterdam, The Netherlands.
Tjaart P J
TP
Krüger
Cristian
C
Ilioaia
Matthew P
MP
Johnson
Alexander V
AV
Ruban
Emmanouil
E
Papagiannakis
Peter
P
Horton
Rienk
R
van Grondelle
D002499:Centrifugation, Density Gradient; D005453:Fluorescence; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D055668:Photochemical Processes; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism*; D010860:Pigments, Biological / Q000378:metabolism; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D018724:Spinacia oleracea / Q000378:metabolism*; D013816:Thermodynamics
D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex; D010860:Pigments, Biological