title: Light-harvesting complex Lhcb9 confers a green alga-type photosystem I supercomplex to the moss Physcomitrella patens.
abstract: Light-harvesting complex (LHC) proteins in chloroplast thylakoid membranes not only transfer absorbed light energy to the two photosystems but also regulate the rate of energy transfer to avoid photodamage. Here we demonstrate that Lhcb9, a recently discovered LHC protein in the moss Physcomitrella patens, functions to connect LHC proteins with photosystem I (PSI), resulting in the formation of two different types of PSI supercomplexes in thylakoid membranes. We observed that the Lhcb9-containing PSI supercomplex is disassembled in response to excess light conditions. On the basis of our phylogenetic analysis, it appears that P. patens acquired Lhcb9 by horizontal gene transfer from the earlier green algal lineage, leading to the presence of both green alga-type and vascular plant-type PSI supercomplexes, which would have been crucial for conquering the dynamic environmental interface between aquatic and terrestrial conditions it faced during evolution.
authors.affiliation: Live Cell Molecular Imaging Research Team, Extreme Photonics Research Group, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|PRESTO, Japan Science and Technology Agency (JST), Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Iwai
authors.affiliation: Institute of Low Temperature Science, Hokkaido University, Sapporo, Hokkaido 060-0819 Japan.
authors.forename: Makio
authors.initials: M
authors.lastname: Yokono
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Kono
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Ko
authors.initials: K
authors.lastname: Noguchi
authors.affiliation: Molecular Photoscience Research Center, Kobe University, Kobe 657-8501, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Akimoto
authors.affiliation: Live Cell Molecular Imaging Research Team, Extreme Photonics Research Group, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Nakano