ジャーナル: Biochim Biophys Acta / 年: 2016 タイトル: Characterization of red-shifted phycobilisomes isolated from the chlorophyll f-containing cyanobacterium Halomicronema hongdechloris. 著者: Yaqiong Li / Yuankui Lin / Christopher J Garvey / Debra Birch / Robert W Corkery / Patrick C Loughlin / Hugo Scheer / Robert D Willows / Min Chen / 要旨: Phycobilisomes are the main light-harvesting protein complexes in cyanobacteria and some algae. It is commonly accepted that these complexes only absorb green and orange light, complementing ...Phycobilisomes are the main light-harvesting protein complexes in cyanobacteria and some algae. It is commonly accepted that these complexes only absorb green and orange light, complementing chlorophyll absorbance. Here, we present a new phycobilisome derived complex that consists only of allophycocyanin core subunits, having red-shifted absorption peaks of 653 and 712 nm. These red-shifted phycobiliprotein complexes were isolated from the chlorophyll f-containing cyanobacterium, Halomicronema hongdechloris, grown under monochromatic 730 nm-wavelength (far-red) light. The 3D model obtained from single particle analysis reveals a double disk assembly of 120-145 Å with two α/β allophycocyanin trimers fitting into the two separated disks. They are significantly smaller than typical phycobilisomes formed from allophycocyanin subunits and core-membrane linker proteins, which fit well with a reduced distance between thylakoid membranes observed from cells grown under far-red light. Spectral analysis of the dissociated and denatured phycobiliprotein complexes grown under both these light conditions shows that the same bilin chromophore, phycocyanobilin, is exclusively used. Our findings show that red-shifted phycobilisomes are required for assisting efficient far-red light harvesting. Their discovery provides new insights into the molecular mechanisms of light harvesting under extreme conditions for photosynthesis, as well as the strategies involved in flexible chromatic acclimation to diverse light conditions.
全体 : Red-shifted phycobilisomes from Halomicronema hongdechloris
全体
名称: Red-shifted phycobilisomes from Halomicronema hongdechloris
要素
試料: Red-shifted phycobilisomes from Halomicronema hongdechloris
タンパク質・ペプチド: APC phycobilisome complex
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超分子 #1000: Red-shifted phycobilisomes from Halomicronema hongdechloris
超分子
名称: Red-shifted phycobilisomes from Halomicronema hongdechloris タイプ: sample / ID: 1000 / 集合状態: Two APC trimers linked with APC E / Number unique components: 1
Chain - #0 - Chain ID: A / Chain - #1 - Chain ID: B
ソフトウェア
名称: Chimera
詳細
Two trimers were fitted to each end of the EM map. 98% of atoms fit within the map at contour level 0.87.
精密化
空間: REAL / プロトコル: RIGID BODY FIT
得られたモデル
PDB-3jbb: Characterization of red-shifted phycobiliprotein complexes isolated from the chlorophyll f-containing cyanobacterium Halomicronema hongdechloris