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ID 48700
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Author
Nagao, Ryo
Moriguchi, Akira
Tomo, Tatsuya
Niikura, Ayako
Nakajima, Saori
Suzuki, Takehiro
Okumura, Akinori
Iwai, Masako
Ikeuchi, Masahiko
Enami, Isao
Abstract
Oxygen-evolving photosystem II (PSII) isolated from a marine centric diatom, Chaetoceros gracilis, contains a novel extrinsic protein (Psb31) in addition to four red algal type extrinsic proteins of PsbO, PsbQ′, PsbV, and PsbU. In this study, the five extrinsic proteins were purified from alkaline Tris extracts of the diatom PSII by anion and cation exchange chromatographic columns at different pH values. Reconstitution experiments in various combinations with the purified extrinsic proteins showed that PsbO, PsbQ′, and Psb31 rebound directly to PSII in the absence of other extrinsic proteins, indicating that these extrinsic proteins have their own binding sites in PSII intrinsic proteins. On the other hand, PsbV and PsbU scarcely rebound to PSII alone, and their effective bindings required the presence of all of the other extrinsic proteins. Interestingly, PSII reconstituted with Psb31 alone considerably restored the oxygen evolving activity in the absence of PsbO, indicating that Psb31 serves as a substitute in part for PsbO in supporting oxygen evolution. A significant difference found between PSIIs reconstituted with Psb31 and with PsbO is that the oxygen evolving activity of the former is scarcely stimulated by Cl− and Ca2+ ions but that of the latter is largely stimulated by these ions, although rebinding of PsbV and PsbU activated oxygen evolution in the absence of Cl− and Ca2+ ions in both the former and latter PSIIs. Based on these results, we proposed a model for the association of the five extrinsic proteins with intrinsic proteins in diatom PSII and compared it with those in PSIIs from the other organisms.
Published Date
2010-09-17
Publication Title
The Journal of Biological Chemistry
Volume
volume285
Issue
issue38
Publisher
The American Society for Biochemistry and Molecular Biology, Inc.
Start Page
29191
End Page
29199
ISSN
0021-9258
NCID
AA00251083
Content Type
Journal Article
Project
Research Center of New Functional Materials for Energy Production, Storage, and Transport
Official Url
http://www.jbc.org/content/285/38/29191.abstract#aff-2
language
英語
Copyright Holders
© 2010 by The American Society for Biochemistry and Molecular Biology, Inc.
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Refereed
True
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