期刊
BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS
卷 1857, 期 9, 页码 1580-1593出版社
ELSEVIER
DOI: 10.1016/j.bbabio.2016.06.007
关键词
Photosystem II; Fluorescence; Lowest excited states; CP47; Circularly polarized luminescence; PsbS
资金
- Australian Research Council [DP110104565, DP150103137]
- Austrian Science Fund (FWF) [P24774-N27]
- Spanish MINECO
- European FEDER [AGL2014-55300-R]
- Austrian Science Fund (FWF) [P 24774] Funding Source: researchfish
- Austrian Science Fund (FWF) [P24774] Funding Source: Austrian Science Fund (FWF)
The identification of low-energy chlorophyll pigments in photosystem II (PSII) is critical to our understanding of the kinetics and mechanism of this important enzyme. We report parallel circular dichroism (CD) and circularly polarized luminescence (CPL) measurements at liquid helium temperatures of the proximal antenna protein CP47. This assembly hosts the lowest-energy chlorophylls in PSII, responsible for the well-known F695 fluorescence band of thylakoids and PSII core complexes. Our new spectra enable a clear identification of the lowest energy exciton state of CP47. This state exhibits a small but measurable excitonic delocalization, as predicated by its CD and CPL. Using structure-based simulations incorporating the new spectra, we propose a revised set of site energies for the 16 chlorophylls of CP47. The significant difference from previous analyses is that the lowest-energy pigment is assigned as Chl 612 (alternately numbered Chl11). The new assignment is readily reconciled with the large number of experimental observations in the literature, while the most common previous assignment for the lowest energy pigment, Chl 627(29), is shown to be inconsistent with CD and CPL results. Chl 612(11) is near the peripheral light-harvesting system in higher plants, in a lumen-exposed region of the thylakoid membrane. The low-energy pigment is also near a recently proposed binding site of the PsbS protein. This result consequently has significant implications for our understanding of the kinetics and regulation of energy transfer in PSII. (C) 2016 Elsevier B.V. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据