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ID 48704
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Author
Takasaka, Kenji
Iwai, Masako
Umena, Yasufumi
Kawakami, Keisuke
Ohmori, Yukari
Ikeuchi, Masahiko
Kamiya, Nobuo
Abstract
Ycf12 (Psb30) and PsbZ are two low molecular weight subunits of photosystem II (PSII), with one and two trans-membrane helices, respectively. In order to study the functions of these two subunits from a structural point of view, we constructed deletion mutants lacking either Ycf12 or PsbZ from Thermosynechococcus elongatus, and purified, crystallized and analyzed the structure of PSII dimer from the two mutants. Our results showed that Ycf12 is located in the periphery of PSII, close to PsbK, PsbZ and PsbJ, and corresponded to the unassigned helix X1 reported previously, in agreement with the recent structure at 2.9 Å resolution (A. Guskov, J. Kern, A. Gabdulkhakov, M. Broser, A. Zouni, W. Saenger, Cyanobacterial photosystem II at 2.9 Å resolution: role of quinones, lipids, channels and chloride, Nat. Struct. Mol. Biol. 16 (2009) 334–342). On the other hand, crystals of PsbZ-deleted PSII showed a remarkably different unit cell constants from those of wild-type PSII, indicating a role of PsbZ in the interactions between PSII dimers within the crystal. This is the first example for a different arrangement of PSII dimers within the cyanobacterial PSII crystals. PSII dimers had a lower oxygen-evolving activity from both mutants than that from the wild type. In consistent with this, the relative content of PSII in the thylakoid membranes was lower in the two mutants than that in the wild type. These results suggested that deletion of both subunits affected the PSII activity, thereby destabilized PSII, leading to a decrease in the PSII content in vivo. While PsbZ was present in PSII purified from the Ycf12-deletion mutant, Ycf12 was present in crude PSII but absent in the finally purified PSII from the PsbZ-deletion mutant, indicating a preferential, stabilizing role of PsbZ for the binding of Ycf12 to PSII. These results were discussed in terms of the PSII crystal structure currently available
Keywords
Photosystem II
Mutant
Crystal structure
Ycf12
PsbZ
Oxygen evolution
Published Date
2010-02
Publication Title
Biochimica et Biophysica Acta (BBA) - Bioenergetics
Volume
volume1797
Issue
issue2
Publisher
Elsevier Science BV.
Start Page
278
End Page
284
ISSN
0005-2728
NCID
AA00564646
Content Type
Journal Article
Project
Research Center of New Functional Materials for Energy Production, Storage, and Transport
Official Url
http://www.sciencedirect.com/science/article/pii/S0005272809002783
language
英語
Copyright Holders
© 2009 Elsevier B.V. All rights reserved.
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Refereed
True
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