TY - JOUR
T1 - ApcD is necessary for efficient energy transfer from phycobilisomes to photosystem I and helps to prevent photoinhibition in the cyanobacterium Synechococcus sp. PCC 7002
AU - Dong, Chunxia
AU - Tang, Aihui
AU - Zhao, Jindong
AU - Mullineaux, Conrad W.
AU - Shen, Gaozhong
AU - Bryant, Donald A.
N1 - Funding Information:
The research in this report was supported by grants from The National Natural Science Foundation of China (no. 30230040) and the Ministry of Science and Technology of China (2009CB11850) to J.Z.; by a grant from the Wellcome Trust and the Biotechnology and Biological Sciences Research Council to C.W.M.; and by grant MCB-0519743 from the U.S. National Science Foundation to D.A.B.
PY - 2009/9
Y1 - 2009/9
N2 - Phycobilisomes (PBS) are the major light-harvesting, protein-pigment complexes in cyanobacteria and red algae. PBS absorb and transfer light energy to photosystem (PS) II as well as PS I, and the distribution of light energy from PBS to the two photosystems is regulated by light conditions through a mechanism known as state transitions. In this study the quantum efficiency of excitation energy transfer from PBS to PS I in the cyanobacterium Synechococcus sp. PCC 7002 was determined, and the results showed that energy transfer from PBS to PS I is extremely efficient. The results further demonstrated that energy transfer from PBS to PS I occurred directly and that efficient energy transfer was dependent upon the allophycocyanin-B alpha subunit, ApcD. In the absence of ApcD, cells were unable to perform state transitions and were trapped in state 1. Action spectra showed that light energy transfer from PBS to PS I was severely impaired in the absence of ApcD. An apcD mutant grew more slowly than the wild type in light preferentially absorbed by phycobiliproteins and was more sensitive to high light intensity. On the other hand, a mutant lacking ApcF, which is required for efficient energy transfer from PBS to PS II, showed greater resistance to high light treatment. Therefore, state transitions in cyanobacteria have two roles: (1) they regulate light energy distribution between the two photosystems; and (2) they help to protect cells from the effects of light energy excess at high light intensities.
AB - Phycobilisomes (PBS) are the major light-harvesting, protein-pigment complexes in cyanobacteria and red algae. PBS absorb and transfer light energy to photosystem (PS) II as well as PS I, and the distribution of light energy from PBS to the two photosystems is regulated by light conditions through a mechanism known as state transitions. In this study the quantum efficiency of excitation energy transfer from PBS to PS I in the cyanobacterium Synechococcus sp. PCC 7002 was determined, and the results showed that energy transfer from PBS to PS I is extremely efficient. The results further demonstrated that energy transfer from PBS to PS I occurred directly and that efficient energy transfer was dependent upon the allophycocyanin-B alpha subunit, ApcD. In the absence of ApcD, cells were unable to perform state transitions and were trapped in state 1. Action spectra showed that light energy transfer from PBS to PS I was severely impaired in the absence of ApcD. An apcD mutant grew more slowly than the wild type in light preferentially absorbed by phycobiliproteins and was more sensitive to high light intensity. On the other hand, a mutant lacking ApcF, which is required for efficient energy transfer from PBS to PS II, showed greater resistance to high light treatment. Therefore, state transitions in cyanobacteria have two roles: (1) they regulate light energy distribution between the two photosystems; and (2) they help to protect cells from the effects of light energy excess at high light intensities.
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U2 - 10.1016/j.bbabio.2009.04.007
DO - 10.1016/j.bbabio.2009.04.007
M3 - Article
C2 - 19397890
AN - SCOPUS:67649488067
SN - 0005-2728
VL - 1787
SP - 1122
EP - 1128
JO - Biochimica et Biophysica Acta - Bioenergetics
JF - Biochimica et Biophysica Acta - Bioenergetics
IS - 9
ER -