Evolution and functional properties of Photosystem II light harvesting complexes in eukaryotes

Abstract

Photoautotrophic organisms, the major agent of inorganic carbon fixation into biomass, convert light energy into chemical energy. The first step of photosynthesis consists of the absorption of solar energy by pigments binding protein complexes named photosystems. Within photosystems, a family of proteins called Light Harvesting Complexes (LHC), responsible for light harvesting and energy transfer to reaction centers, has evolved along with eukaryotic organisms. Besides light absorption, these proteins catalyze photoprotective reactions which allowed functioning of oxygenic photosynthetic machinery in the increasingly oxidant environment. In this work we review current knowledge of LHC proteins serving Photosystem II. Balance between light harvesting and photoprotection is critical in Photosystem II, due to the lower quantum efficiency as compared to Photosystem I. In particular, we focus on the role of each antenna complex in light harvesting, energy transfer, scavenging of reactive oxygen species, chlorophyll triplet quenching and thermal dissipation of excess energy. This article is part of a Special Issue entitled: Photosystem II.

Heterologous Expression of Moss Light-harvesting Complex Stress-related 1 (LHCSR1), the Chlorophyll a-Xanthophyll Pigment-protein Complex Catalyzing Non-photochemical Quenching, in Nicotiana sp.

“…8C) this suggests that the most likely state of LHCSR1 is a homodimer. LHC proteins can be found as trimers (LHCII), monomers (CP29, CP26, and CP24), and dimers (LHCAs) (55)(56)(57). For both the LHC-like proteins involved in NPQ triggering, namely PSBS and LHCSR3 from Chlamydomonas, there have been reports of dimeric organization, although in most conditions, the most abundant form was a monomer (20,22,39).…”

MET1 Is a Thylakoid-Associated TPR Protein Involved in Photosystem II Supercomplex Formation and Repair in Arabidopsis

“…After the sequential formation of the monomeric and dimeric PSII core (C2), minor and major LHCII proteins associate to the PSII dimer to form different sized PSII supercomplexes. The minor LHCII proteins (CP24, CP26, and CP29) provide the molecular interface between the PSII core and the LHCII trimers (LHCII-1,2,3) (Ballottari et al, 2012;Kou ril et al, 2012). The PSII supercomplex (C2S2M2) is the major and largest in vivo form of PSII for Arabidopsis.…”

“…Additionally, there are loosely bound major LHCII trimers (L) that can interact peripherally with the C2S2M2 supercomplex to form larger complexes. These L trimers migrate between PSII and photosystem I (PSI) (Caffarri et al, 2009;Ballottari et al, 2012;Kou ril et al, 2012;Pan et al, 2013). Knockout and knockdown mutants in Arabidopsis thaliana have been described for the major and minor LHCII genes and showed that the CP24, CP26, and CP29 play critical roles in association of LHCII trimers to the PSII core (reviewed in Ballottari et al, 2012).…”

Chlamydomonas reinhardtii PsbS Protein Is Functional and Accumulates Rapidly and Transiently under High Light

“…In these conditions, the excess absorbed energy can be transferred from excited chlorophylls in the triplet state ( 3 Chls*) to molecular O 2 and cause the production of harmful reactive oxygen species (ROS). In plants and green algae most of the light is absorbed by membrane proteins of the Light harvesting complex (Lhc) family (Jansson, 1999;Ballottari et al, 2012;Buchel, 2015), which are associated with photosystem I and II (Dekker and Boekema, 2005;Caffarri et al, 2014) and participate in photoprotection (Duffy and Ruban, 2015).…”