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Photosystem I oligomerization affects lipid composition in Synechocystis sp. PCC 6803

Kovacs, Terezia and Szalontai, Balázs and Kłodawska, Kinga and Vladkova, Radka and Malec, Przemysław and Gombos, Zoltán and Laczkó-Dobos, Hajnalka (2019) Photosystem I oligomerization affects lipid composition in Synechocystis sp. PCC 6803. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR AND CELL BIOLOGY OF LIPIDS, 1864 (10). pp. 1384-1395. ISSN 1388-1981

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Abstract

In cyanobacteria, increasing growth temperature decreases lipid unsaturation and the ratio of monomer/trimer photosystem I (PSI) complexes. In the present study we applied Fourier-transform infrared (FTIR) spectroscopy and lipidomic analysis to study the effects of PSI monomer/oligomer ratio on the physical properties and lipid composition of thylakoids. To enhance the presence of monomeric PSI, a Synechocystis sp. PCC6803/ΔpsaL mutant strain (PsaL) was used which, unlike both trimeric and monomeric PSI-containing wild type (WT) cells, contain only the monomeric form. The protein-to-lipid ratio remained unchanged in the mutant but, due to an increase in the lipid disorder in its thylakoids, the gel to liquid-crystalline phase transition temperature (Tm) is lower than in the WT. In thylakoid membranes of the mutant, digalactosyldiacylglycerol (DGDG), the most abundant bilayer-forming lipid is accumulated, whereas those in the WT contain more monogalactosyldiacylglycerol (MGDG), the only non-bilayer-forming lipid in cyanobacteria. In PsaL cells, the unsaturation level of sulphoquinovosyldiacylglycerol (SQDG), a regulatory anionic lipid, has increased. It seems that merely a change in the oligomerization level of a membrane protein complex (PSI), and thus the altered protein-lipid interface, can affect the lipid composition and, in addition, the whole dynamics of the membrane. Singular value decomposition (SVD) analysis has shown that in PsaL thylakoidal protein-lipid interactions are less stable than in the WT, and proteins start losing their native secondary structure at much milder lipid packing perturbations. Conclusions drawn from this system should be generally applicable for protein-lipid interactions in biological membranes.

Item Type: Article
Uncontrolled Keywords: infrared spectroscopy; Synechocystis; Protein-lipid interaction; Lipidomic analysis; PSI oligomers; PsaL mutant;
Subjects: Q Science / természettudomány > QH Natural history / természetrajz > QH301 Biology / biológia
Q Science / természettudomány > QH Natural history / természetrajz > QH301 Biology / biológia > QH3011 Biochemistry / biokémia
Q Science / természettudomány > QH Natural history / természetrajz > QH301 Biology / biológia > QH3015 Molecular biology / molekuláris biológia
Q Science / természettudomány > QH Natural history / természetrajz > QH301 Biology / biológia > QH3020 Biophysics / biofizika
SWORD Depositor: MTMT SWORD
Depositing User: MTMT SWORD
Date Deposited: 23 Nov 2019 13:14
Last Modified: 23 Nov 2019 13:14
URI: http://real.mtak.hu/id/eprint/103620

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