Journal Article

LHCII can substitute for LHCI as an antenna for photosystem I but with reduced light-harvesting capacity

Alcocer, Marcelo J. P., Dall'Osto, Luca, Bressan, Mauro, Cerullo, Giulio, Viola, Daniele, D'Andrea, Cosimo, Bassi, Roberto, Ballottari, Matteo, Bargigia, Ilaria

2016

Overview

Light-harvesting complexes (LHCs) are major constituents of the antenna systems in higher plant photosystems. Four Lhca subunits are tightly bound to the photosystem I (PSI) core complex, forming its outer antenna moiety called LHCI. The Arabidopsis thaliana mutant ΔLhca lacks all Lhca1–4 subunits and compensates for its decreased antenna size by binding LHCII trimers, the main constituent of the photosystem II antenna system, to PSI. In this work we have investigated the effect of LHCI/LHCII substitution by comparing the light harvesting and excitation energy transfer efficiency properties of PSI complexes isolated from ΔLhca mutants and from the wild type, as well as the consequences for plant growth. We show that the excitation energy transfer efficiency was not compromised by the substitution of LHCI with LHCII but a significant reduction in the absorption cross-section was observed. The absence of LHCI subunits in PSI thus significantly limits light harvesting, even on LHCII binding, inducing, as a consequence, a strong reduction in growth. A quadruple mutant of Arabidopsis lacking all four subunits of light harvesting complex I (LHCI) compensates by binding LHCII complexes to photosystem I instead. This maintained similar excitation energy transfer efficiency but with a much reduced absorption cross-section.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 45/29 / 45/77 / 45/88 / 45/90 / 631/449/1734/2075 / 631/449/1734/2077 / 82/1 / Absorption / Absorption cross sections / Antennas / Arabidopsis - metabolism / Arabidopsis Proteins - metabolism / Binding / Biomedical and Life Sciences / Chlorophyll Binding Proteins - metabolism / Constituents / Cross-sections / Efficiency / Energy harvesting / Energy Transfer / Excitation / Life Sciences / Mutants / Photosynthesis / Photosystem I / Photosystem I Protein Complex - metabolism / Photosystem II / Plant growth / Plant Sciences / Reduction / Substitutes / Trimers