4XXI

Crystal structure of the Bilin-binding domain of phycobilisome core-membrane linker ApcE

4XXI の概要

• エントリーDOI: 10.2210/pdb4xxi/pdb
• 関連するPDBエントリー: 4XXK
• 分子名称: Phycobiliprotein ApcE, PHYCOCYANOBILIN (3 entities in total)
• 機能のキーワード: apce, phycobilisome, phycocyanobilin attachment, transferase
• 由来する生物種: Nostoc sp. (strain PCC 7120 / UTEX 2576)
• 細胞内の位置: Cellular thylakoid membrane ; Peripheral membrane protein ; Cytoplasmic side : P80559
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 36531.59

構造登録者

Tang, K.,Ding, W.-L.,Hoppner, A.,Gartner, W.,Zhao, K.-H. (登録日: 2015-01-30, 公開日: 2015-12-16, 最終更新日: 2023-11-08)

主引用文献

Tang, K.,Ding, W.-L.,Hoppner, A.,Zhao, C.,Zhang, L.,Hontani, Y.,Kennis, J.T.M.,Gartner, W.,Scheer, H.,Zhou, M.,Zhao, K.-H.
The terminal phycobilisome emitter, LCM: A light-harvesting pigment with a phytochrome chromophore
Proc.Natl.Acad.Sci.USA, 112:15880-15885, 2015

PubMed Abstract: Photosynthesis relies on energy transfer from light-harvesting complexes to reaction centers. Phycobilisomes, the light-harvesting antennas in cyanobacteria and red algae, attach to the membrane via the multidomain core-membrane linker, L(CM). The chromophore domain of L(CM) forms a bottleneck for funneling the harvested energy either productively to reaction centers or, in case of light overload, to quenchers like orange carotenoid protein (OCP) that prevent photodamage. The crystal structure of the solubly modified chromophore domain from Nostoc sp. PCC7120 was resolved at 2.2 Å. Although its protein fold is similar to the protein folds of phycobiliproteins, the phycocyanobilin (PCB) chromophore adopts ZZZssa geometry, which is unknown among phycobiliproteins but characteristic for sensory photoreceptors (phytochromes and cyanobacteriochromes). However, chromophore photoisomerization is inhibited in L(CM) by tight packing. The ZZZssa geometry of the chromophore and π-π stacking with a neighboring Trp account for the functionally relevant extreme spectral red shift of L(CM). Exciton coupling is excluded by the large distance between two PCBs in a homodimer and by preservation of the spectral features in monomers. The structure also indicates a distinct flexibility that could be involved in quenching. The conclusions from the crystal structure are supported by femtosecond transient absorption spectra in solution.

PubMed: 26669441
DOI: 10.1073/pnas.1519177113

実験手法

X-RAY DIFFRACTION (2.2 Å)