Crystal structure of spinach major light-harvesting complex at 2.72 A resolution.
The major light-harvesting complex of photosystem II (LHC-II) serves as the principal solar energy collector in the photosynthesis of green plants and presumably also functions in photoprotection under high-light conditions. Here we report the first X-ray structure of LHC-II in icosahedral proteoliposome assembly at atomic detail. One asymmetric unit of a large R32 unit cell contains ten LHC-II monomers. The 14 chlorophylls (Chl) in each monomer can be unambiguously distinguished as eight Chla and six Chlb molecules. Assignment of the orientation of the transition dipole moment of each chlorophyll has been achieved. All Chlb are located around the interface between adjacent monomers, and together with Chla they are the basis for efficient light harvesting. Four carotenoid-binding sites per monomer have been observed. The xanthophyll-cycle carotenoid at the monomer-monomer interface may be involved in the non-radiative dissipation of excessive energy, one of the photoprotective strategies that have evolved in plants.
Liu
Zhenfeng
Z
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, People's Republic of China.
Yan
Hanchi
H
Wang
Kebin
K
Kuang
Tingyun
T
Zhang
Jiping
J
Gui
Lulu
L
An
Xiaomin
X
Chang
Wenrui
W
D001059:Apoproteins / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002338:Carotenoids / Q000737:chemistry / Q000378:metabolism; D002734:Chlorophyll / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D011510:Proteolipids / Q000737:chemistry / Q000378:metabolism; D018724:Spinacia oleracea / Q000737:chemistry*
D001059:Apoproteins; D045342:Light-Harvesting Protein Complexes; D011510:Proteolipids; C020485:proteoliposomes; D002734:Chlorophyll; D002338:Carotenoids