7YTF

Structure of OCPx2 from Nostoc flagelliforme CCNUN1

7YTF の概要

• エントリーDOI: 10.2210/pdb7ytf/pdb
• 分子名称: Ketosteroid isomerase-related protein, beta,beta-carotene-4,4'-dione (3 entities in total)
• 機能のキーワード: ocp protein, photosynthesis
• 由来する生物種: Nostoc flagelliforme CCNUN1
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 36766.91

構造登録者

Yang, Y.W.,Chen, S.Z.,Liu, K.,Chen, M.,Qiu, B.S. (登録日: 2022-08-14, 公開日: 2023-06-21, 最終更新日: 2023-11-29)

主引用文献

Yang, Y.W.,Liu, K.,Huang, D.,Yu, C.,Chen, S.Z.,Chen, M.,Qiu, B.S.
Functional specialization of expanded orange carotenoid protein paralogs in subaerial Nostoc species.
Plant Physiol., 192:2640-2655, 2023

PubMed Abstract: Orange carotenoid protein (OCP) is a photoactive protein that participates in the photoprotection of cyanobacteria. There are 2 full-length OCP proteins, 4 N-terminal paralogs (helical carotenoid protein [HCP]), and 1 C-terminal domain-like carotenoid protein (CCP) found in Nostoc flagelliforme, a desert cyanobacterium. All HCPs (HCP1 to 3 and HCP6) from N. flagelliforme demonstrated their excellent singlet oxygen quenching activities, in which HCP2 was the strongest singlet oxygen quencher compared with others. Two OCPs, OCPx1 and OCPx2, were not involved in singlet oxygen scavenging; instead, they functioned as phycobilisome fluorescence quenchers. The fast-acting OCPx1 showed more effective photoactivation and stronger phycobilisome fluorescence quenching compared with OCPx2, which behaved differently from all reported OCP paralogs. The resolved crystal structure and mutant analysis revealed that Trp111 and Met125 play essential roles in OCPx2, which is dominant and long acting. The resolved crystal structure of OCPx2 is maintained in a monomer state and showed more flexible regulation in energy quenching activities compared with the packed oligomer of OCPx1. The recombinant apo-CCP obtained the carotenoid pigment from holo-HCPs and holo-OCPx1 of N. flagelliforme. No such carotenoid transferring processes were observed between apo-CCP and holo-OCPx2. The close phylogenetic relationship of OCP paralogs from subaerial Nostoc species indicates an adaptive evolution toward development of photoprotection: protecting cellular metabolism against singlet oxygen damage using HCPs and against excess energy captured by active phycobilisomes using 2 different working modes of OCPx.

PubMed: 37070859
DOI: 10.1093/plphys/kiad234

実験手法

X-RAY DIFFRACTION (2.65 Å)