In nature, plants are continuously exposed to varying environmental conditions. They have developed a wide range of adaptive mechanisms, which ensure their survival and maintenance of stable photosynthetic performance. Photosynthesis is delicately regulated at the level of the thylakoid membrane of chloroplasts and the regulatory mechanisms include a reversible formation of a large variety of specific protein-protein complexes, supercomplexes or even larger assemblies known as megacomplexes. Revealing their structures is crucial for better understanding of their function and relevance in photosynthesis. Here we focus our attention on the isolation and a structural characterization of various large protein supercomplexes and megacomplexes, which involve Photosystem II and Photosystem I, the key constituents of photosynthetic apparatus. The photosystems are often attached to other protein complexes in thylakoid membranes such as light harvesting complexes, cytochrome b 6 f complex, and NAD(P)H dehydrogenase. Structural models of individual supercomplexes and megacomplexes provide essential details of their architecture, which allow us to discuss their function as well as physiological significance.

Department of Biophysics Faculty of Science Centre of the Region Haná for Biotechnological and Agricultural Research Palacký University Olomouc Czech Republic

Electron Microscopy Group Groningen Biomolecular Sciences and Biotechnology Institute University of Groningen Groningen The Netherlands

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Photosystem II supercomplexes lacking light-harvesting antenna protein LHCB5 and their organization in the thylakoid membrane

Cryo-EM structure of a plant photosystem II supercomplex with light-harvesting protein Lhcb8 and α-tocopherol

Spruce versus Arabidopsis: different strategies of photosynthetic acclimation to light intensity change

A kaleidoscope of photosynthetic antenna proteins and their emerging roles

Towards spruce-type photosystem II: consequences of the loss of light-harvesting proteins LHCB3 and LHCB6 in Arabidopsis

Revealing the architecture of the photosynthetic apparatus in the diatom Thalassiosira pseudonana

Unique organization of photosystem II supercomplexes and megacomplexes in Norway spruce