Light-induced formation of dimeric LHCII
Ewa Janik1,2, Joanna Bednarska3,4, Karol Sowinski3,5
1Department of Biophysics, Institute of Physics, Maria Curie-Sklodowska University, Pl. Marii Curie-Sklodowskiej 1, 20-031, Lublin, Poland. ewa.janik@poczta.umcs.lublin.pl.
Photosynthesis Research
|April 21, 2017
Summary
The major photosynthetic antenna complex of plants, LHCII, exists not only as trimers or monomers but also as dimers. This study reveals LHCII dimers can be a distinct physiological form, potentially aiding photoprotection.
Area of Science:
- Photosynthesis research
- Plant molecular biology
- Biophysics of light-harvesting complexes
Background:
- The Light-Harvesting Complex II (LHCII) is the primary antenna complex in plant photosynthesis.
- LHCII is known to exist in trimeric and monomeric forms.
- The potential physiological relevance of LHCII dimers has been unclear.
Purpose of the Study:
- To investigate whether LHCII dimers represent a transient intermediate or a physiologically relevant state.
- To characterize the different forms of LHCII dimers and their properties.
Main Methods:
- Native electrophoresis
- Time-resolved fluorescence spectroscopy
- Fluorescence correlation spectroscopy
Main Results:
- Two distinct types of LHCII dimers were identified.
- One dimer type arises from trimer dissociation; the other is a unique monomer association.
- The second dimer type exhibits rapid chlorophyll excitation quenching, suggesting an energy-quenching role.
Conclusions:
- LHCII dimers are not merely intermediates but can be distinct functional entities.
- A hypothetical structure for the energy-quenching LHCII dimer is proposed.
- High light-induced LHCII dimerization may function as a photoprotective mechanism in plants.
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