Light-induced formation of dimeric LHCII

Ewa Janik,Wieslaw I Gruszecki,Karol Sowinski,Wojciech Grudzinski,Rafal Luchowski,Joanna Bednarska,Monika Zubik

doi:10.1007/s11120-017-0387-6

Abstract

It emerges from numerous experiments that LHCII, the major photosynthetic antenna complex of plants, can appear not only in the trimeric or monomeric states but also as a dimer. We address the problem whether the dimeric form of the complex is just a simple intermediate element of the trimer–monomer transformation or if it can also be a physiologically relevant molecular organization form? Dimers of LHCII were analyzed with application of native electrophoresis, time-resolved fluorescence spectroscopy, and fluorescence correlation spectroscopy. The results reveal the appearance of two types of LHCII dimers: one formed by the dissociation of one monomer from the trimeric structure and the other formed by association of monomers into a distinctively different molecular organizational form, characterized by a high rate of chlorophyll excitation quenching. The hypothetical structure of such an energy quencher is proposed. The high light-induced LHCII dimerization is discussed as a potential element of the photoprotective response in plants.

Highlights

Green plants, algae, and some species of bacteria utilize light energy to power photosynthetic reactions
The light-harvesting pigment–protein complex of PSII (LHCII) complexes were isolated from spinach leaves that were dark-adapted or illuminated with high light according to the methods described in (Krupa et al 1987) or (Janik et al 2013), respectively
According to our previous observations, appearance of a dimeric form of LHCII can be discerned in process of zeaxanthin-induced trimer disassembling (Janik et al 2016)

Summary

Introduction

Algae, and some species of bacteria utilize light energy to power photosynthetic reactions. It is known that the yield of photosynthesis depends strongly on the intensity of absorbed light. The light conditions vary greatly in intensity and quality on a broad time scale, ranging from minutes up to hours, days, and even months. These changes can result from environmental factors such as cloud movement, sun flecks, weather system, or sudden shading by other plants and changes in the canopy structure (Owens 1994).

Present Address

Materials and methods

Results and discussion