Photosystem II Complex in Vivo Is a Monomer*
- Takeshi Takahashi‡,1,
- Natsuko Inoue-Kashino‡§,1,
- Shin-ichiro Ozawa§,
- Yuichiro Takahashi§,
- Yasuhiro Kashino‡,2 and
- Kazuhiko Satoh‡
- From the ‡Graduate School of Life Science, University of Hyogo, 3-2-1 Kohto, Kamigohri, Ako-gun, Hyogo 678-1297 and the
- §Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-Naka, Okayama 700-8530, Japan
- 2 To whom correspondence should be addressed: Graduate School of Life Science, University of Hyogo, 3-2-1 Kohto, Kamigohri, Ako-gun, Hyogo 678-1297, Japan. Tel./Fax: 81-791-58-0185; E-mail: kashino{at}sci.u-hyogo.ac.jp.
-
↵1 Both authors contributed equally to this work.
Abstract
Photosystem II (PS II) complexes are membrane protein complexes that are composed of >20 distinct subunit proteins. Similar to many other membrane protein complexes, two PS II complexes are believed to form a homo-dimer whose molecular mass is ∼650 kDa. Contrary to this well known concept, we propose that the functional form of PS II in vivo is a monomer, based on the following observations. Deprivation of lipids caused the conversion of PS II from a monomeric form to a dimeric form. Only a monomeric PS II was detected in solubilized cyanobacterial and red algal thylakoids using blue-native polyacrylamide gel electrophoresis. Furthermore, energy transfer between PS II units, which was observed in the purified dimeric PS II, was not detected in vivo. Our proposal will lead to a re-evaluation of many crystallographic models of membrane protein complexes in terms of their oligomerization status.
Footnotes
-
↵* This work was supported by MEXT (Grant 20051021 to Y. K. and Grant 18GS0318 to Y. T.), from Hyogo Science and Technology Association (Grant 20I107 to Y. K.), GCOE Program from MEXT (to K. S.), and by Sasakawa Scientific Research Grants from The Japan Science Society (17–166 to T. T. and 19-440 to N. I.-K.).
-
↵
The on-line version of this article (available at http://www.jbc.org) contains supplemental Figs. S1–S3 and Tables S1–S3.
-
↵3 The abbreviations used are:
- PS I and PS II
-
photosystem I and II
- BN
-
blue native
- Chl
-
chlorophyll
- ClogP
-
the calculated logarithm of the partition coefficient
- 2,5-DCBQ
-
2,5-dichloro-p-benzoquinone
- DCMU
-
3-(3,4-dichlorophenyl)-1,1-dimethyl urea
- DDM
-
n-dodecyl-β-d-maltoside
- LHCII
-
light-harvesting Chl-binding proteins
- MES
-
2-(N-morpholino)ethanesulfonic acid
- LC
-
liquid chromatography
- MS/MS
-
tandem mass spectrometry.
-
- Received March 3, 2009.
- Revision received April 5, 2009.
- © 2009 by The American Society for Biochemistry and Molecular Biology, Inc.
