Lipid Polymorphism of the Subchloroplast-Granum and Stroma Thylakoid Membrane-Particles. II. Structure and Functions

0549353 - ÚVGZ 2022 RIV CH eng J - Journal Article
Dlouhý, O. - Karlický, Václav - Rameez, A. - Zsiros, O. - Domonkos, I. - Kurasová, Irena - Wacha, A. F. - Morosinotto, T. - Bota, A. - Kouřil, R. - Špunda, Vladimír - Garab, G.
Lipid Polymorphism of the Subchloroplast-Granum and Stroma Thylakoid Membrane-Particles. II. Structure and Functions.
Cells. Roč. 10, č. 9 (2021), č. článku 2363. E-ISSN 2073-4409
R&D Projects: GA MŠMT(CZ) EF16_019/0000797; GA MŠMT(CZ) LM2018123
Research Infrastructure: CzeCOS III - 90123
Institutional support: RVO:86652079
Keywords : light-harvesting-complex * violaxanthin de-epoxidase * photosystem-ii * nonbilayer lipids * induced detachment * thermal-stability * respiratory-chain * phase-behavior * higher-plants * atp synthase * bilayer * chlorophyll fluorescence * cryo-electron-tomography * electron microscopy * membrane energization * membrane networks * non-bilayer lipid phases * saxs * violaxanthin de-epoxidase
OECD category: Biophysics
Impact factor: 7.666, year: 2021
Method of publishing: Open access
https://www.mdpi.com/2073-4409/10/9/2363

In Part I, by using P-31-NMR spectroscopy, we have shown that isolated granum and stroma thylakoid membranes (TMs), in addition to the bilayer, display two isotropic phases and an inverted hexagonal (H-II) phase, saturation transfer experiments and selective effects of lipase and thermal treatments have shown that these phases arise from distinct, yet interconnectable structural entities. To obtain information on the functional roles and origin of the different lipid phases, here we performed spectroscopic measurements and inspected the ultrastructure of these TM fragments. Circular dichroism, 77 K fluorescence emission spectroscopy, and variable chlorophyll-a fluorescence measurements revealed only minor lipase- or thermally induced changes in the photosynthetic machinery. Electrochromic absorbance transients showed that the TM fragments were re-sealed, and the vesicles largely retained their impermeabilities after lipase treatments-in line with the low susceptibility of the bilayer against the same treatment, as reflected by our P-31-NMR spectroscopy. Signatures of H-II-phase could not be discerned with small-angle X-ray scattering-but traces of H-II structures, without long-range order, were found by freeze-fracture electron microscopy (FF-EM) and cryo-electron tomography (CET). EM and CET images also revealed the presence of small vesicles and fusion of membrane particles, which might account for one of the isotropic phases. Interaction of VDE (violaxanthin de-epoxidase, detected by Western blot technique in both membrane fragments) with TM lipids might account for the other isotropic phase. In general, non-bilayer lipids are proposed to play role in the self-assembly of the highly organized yet dynamic TM network in chloroplasts.
Permanent Link: http://hdl.handle.net/11104/0325367