Small-angle neutron scattering study of the ultrastructure of chloroplast thylakoid membranes — Periodicity and structural flexibility of the stroma lamellae
| Autor: | Dorthe Posselt, Jens Kai Holm, Thomas H. Aagaard, László Rosta, Gergely Nagy, Jacob J. K. Kirkensgaard, Peter Timmins, Eszter Rétfalvi, László Kovács, Gyözö Garab |
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| Rok vydání: | 2012 |
| Předmět: |
Stroma thylakoid membrane
0106 biological sciences Repeat distance Light Biophysics Light-induced reorganization Biology Thylakoids 01 natural sciences Biochemistry Chloroplast thylakoid 03 medical and health sciences Osmotic Pressure Spinacia oleracea Scattering Small Angle Magnesium Small-angle neutron scattering (SANS) Electrochemical gradient 030304 developmental biology Neutrons 0303 health sciences Small-angle X-ray scattering Peas Transmembrane proton gradient food and beverages Granum Cell Biology Small-angle neutron scattering Chloroplast Light intensity Crystallography Membrane Thylakoid 010606 plant biology & botany |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1817:1220-1228 |
| ISSN: | 0005-2728 |
| DOI: | 10.1016/j.bbabio.2012.01.012 |
| Popis: | The multilamellar organization of freshly isolated spinach and pea chloroplast thylakoid membranes was studied using small-angle neutron scattering. A broad peak at ~ 0.02 A− 1 is ascribed to diffraction from domains of ordered, unappressed stroma lamellae, revealing a repeat distance of 294 A ± 7 A in spinach and 345 A ± 11 A in pea. The peak position and hence the repeat distance of stroma lamellae is strongly dependent on the osmolarity and the ionic strength of the suspension medium, as demonstrated by varying the sorbitol and the Mg++-concentration in the sample. For pea thylakoid membranes, we show that the repeat distance decreases when illuminating the sample with white light, in accordance with our earlier results on spinach, also regarding the observation that addition of an uncoupler prohibits the light-induced structural changes, a strong indication that these changes are driven by the transmembrane proton gradient. We show that the magnitude of the shrinkage is strongly dependent on light intensity and that the repeat distance characteristic of the dark state after illumination is different from the initial dark state. Prolonged strong illumination leads to irreversible changes and swelling as reflected in increased repeat distances. The observed reorganizations are discussed within the frames of the current structural models of the granum-stroma thylakoid membrane assembly and the regulatory mechanisms in response to variations in the environmental conditions in vivo. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial. |
| Databáze: | OpenAIRE |
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