Influence of thylakoid membrane lipids on the structure and function of the plant photosystem II core complex
- 954 Downloads
MGDG leads to a dimerization of isolated, monomeric PSII core complexes. SQDG and PG induce a detachment of CP43 from the PSII core, thereby disturbing the intrinsic PSII electron transport.
The influence of the four thylakoid membrane lipids monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfoquinovosyldiacylglycerol (SQDG) and phosphatidylglycerol (PG) on the structure and function of isolated monomeric photosystem (PS) II core complexes was investigated. Incubation with the negatively charged lipids SQDG and PG led to a loss of the long-wavelength 77 K fluorescence emission at 693 nm that is associated with the inner antenna proteins. The neutral galactolipids DGDG and MGDG had no or only minor effects on the fluorescence emission spectra of the PSII core complexes, respectively. Pigment analysis, absorption and 77 K fluorescence excitation spectroscopy showed that incubation with SQDG and PG led to an exposure of chlorophyll molecules to the surrounding medium followed by conversion to pheophytin under acidic conditions. Size-exclusion chromatography and polypeptide analysis corroborated the findings of the spectroscopic measurements and pigment analysis. They showed that the negatively charged lipid SQDG led to a dissociation of the inner antenna protein CP43 and the 27- and 25-kDa apoproteins of the light-harvesting complex II, that were also associated with a part of the PSII core complexes used in the present study. Incubation of PSII core complexes with MGDG, on the other hand, induced an almost complete dimerization of the monomeric PSII. Measurements of the fast PSII fluorescence induction demonstrated that MGDG and DGDG only had a minor influence on the reduction kinetics of plastoquinone QA and the artificial PSII electron acceptor 2,5-dimethyl-p-benzoquinone (DMBQ). SQDG and, to a lesser extent, PG perturbed the intrinsic PSII electron transport significantly.
KeywordsChlorophyll-binding protein 43 (CP43) Digalactosyldiacylglycerol (DGDG) Light-harvesting complex of photosystem II (LHCII) Monogalactosyldiacylglycerol (MGDG) Phosphatidylglycerol (PG) Sulfoquinovosyldiacylglycerol (SQDG)
Fluorescence induction transient
Financial support from the Deutsche Forschungsgemeinschaft (DFG, Grant Go818/7-1) is gratefully acknowledged.
- Gray GR, Ivanov AG, Krol M, Williams JP, Kahn MU, Myscich EG, Huner NPA (2005) Temperature and light modulate the trans-Δ3-hexadecenoic acid content of phosphatidylglycerol: light-harvesting complex II organization and non- photochemical quenching. Plant Cell Physiol 46:1272–1282PubMedCrossRefGoogle Scholar
- Laczkó-Dobos H, Ughy B, Tóth SZ, Komenda J, Zsiros O, Domonkos I, Párducz Á, Bogos B, Komura M, Itoh S, Gombos Z (2008) Role of phosphatidylglycerol in the function and assembly of photosystem II reaction center, studied in a cdsA-inactivated PAL mutant strain of Synechocystis sp. PCC6803 that lacks phycobilisomes. Biochim Biophys Acta 1777:1184–1194PubMedCrossRefGoogle Scholar
- Murata N, Siegenthaler PA (1998) Lipids in photosynthesis: an overview. In: Siegenthaler PA, Murata N (eds) Lipids in photosynthesis: structure, function and genetics. Kluwer Academic Publishers, Dordrecht, pp 1–20Google Scholar
- Wright SW, Mantoura RFC (1997) Guidelines for collection and pigment analysis of field samples. In: Jeffrey SW, Mantoura RFC, Wright SW (eds) Monographs on oceanographic methodology: phytoplankton pigments in oceanography: guidelines to modern methods. Unesco Publishing, Paris, pp 429–445Google Scholar