Abstract
The light reactions of oxygenic photosynthesis take place in the thylakoid membranes, flattened vesicles, which contain the two photosystems and also embed the cytochrome b6f complex and the ATP synthase. In general, the thylakoid membranes are assembled into multilamellar membrane systems, which warrant an optimal light capturing efficiency. In nature, they show astounding variations, primarily due to large variations in their protein composition, which is controlled by multilevel regulatory mechanisms during long-term acclimation and short-term adaptation processes and also influenced by biotic or abiotic stresses - indicating a substantial degree of flexibility in the membrane ultrastructure. The better understanding of the dynamic features of this membrane system requires the use of non-invasive techniques, such as small angle neutron scattering (SANS), which is capable of providing accurate, statistically and spatially averaged information on the repeat distances of periodically organized thylakoid membranes under physiologically relevant conditions with time resolutions of seconds and minutes. In this review, after a short section on the basic properties of neutrons, we outline the fundamental principles of SANS measurements, its strengths and weaknesses in comparison to complementary structure investigation techniques. Then we overview recent results on isolated plant thylakoid membranes, and on living cyanobacterial and algal cells as well as on whole leaves. Special attention is paid to light-induced reversible ultrastructural changes invivo, which, in cyanobacterial and diatom cells, were uncovered with the aid of SANS measurements; we also discuss the role of membrane reorganizations in light adaptation and photoprotection mechanisms.
| Original language | English |
|---|---|
| Pages (from-to) | 197-207 |
| Number of pages | 11 |
| Journal | Plant Physiology and Biochemistry |
| Volume | 81 |
| DOIs | |
| State | Published - Aug 2014 |
| Externally published | Yes |
Funding
The authors would like to thank the Neutron Center (BNC), Budapest, Hungary; Institute Laue-Langevin (ILL), Grenoble, France; Paul Scherrer Institute (PSI), Villigen, Switzerland; Jülich Centre for Neutron Science (JCNS), Garching, Germany for providing beamtimes for different SANS experiments. The related experiments were supported by the Marie Curie Initial Training Network “HARVEST” sponsored by the 7th Framework Program of the European Union (grant number 238017 , to G.G.), the Hungarian Scientific Research Fund/National Office for Research and Technology (grant number 60003-00 (previously 80341 and 80345 and G.G.). R.Ü., G.N. and M.M. obtained partial support from the National Office for Research and Technology (grant number NAP-VENEUS05 ). We are indebted to Prof. D. Posselt for stimulating discussions during numerous jointly performed experiments, and to Prof. L. Rosta for his support and continuous interest in this topic.
| Funders | Funder number |
|---|---|
| Seventh Framework Programme | |
| Nemzeti Kutatási és Technológiai Hivatal | NAP-VENEUS05 |
| European Commission | 238017 |
| Hungarian Scientific Research Fund/National Office for Research and Technology | 80341, 80345, 60003-00 |
Keywords
- Lamellar repeat distance
- Light-induced ultrastructural changes
- Photosynthesis
- Small angle neutron scattering
- Thylakoid membranes