The structural and functional domains of plant thylakoid membranes |
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Authors: | Haniyeh Koochak Sujith Puthiyaveetil Daniel L Mullendore Meng Li Helmut Kirchhoff |
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Institution: | 1. Institute of Biological Chemistry, Washington State University, PO Box 2. 646340, Pullman, WA, 99164‐6340 USA;3. Franceschi Microscopy and Imaging Center, Washington State University, Pullman, WA, 99164 USA;4. 646340, Pullman, WA, 99164‐6340 USAFor correspondence (e‐mail ). |
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Abstract: | In plants, the stacking of part of the photosynthetic thylakoid membrane generates two main subcompartments: the stacked grana core and unstacked stroma lamellae. However, a third distinct domain, the grana margin, has been postulated but its structural and functional identity remains elusive. Here, an optimized thylakoid fragmentation procedure combined with detailed ultrastructural, biochemical, and functional analyses reveals the distinct composition of grana margins. It is enriched with lipids, cytochrome b6f complex, and ATPase while depleted in photosystems and light‐harvesting complexes. A quantitative method is introduced that is based on Blue Native Polyacrylamide Gel Electrophoresis (BN‐PAGE) and dot immunoblotting for quantifying various photosystem II (PSII) assembly forms in different thylakoid subcompartments. The results indicate that the grana margin functions as a degradation and disassembly zone for photodamaged PSII. In contrast, the stacked grana core region contains fully assembled and functional PSII holocomplexes. The stroma lamellae, finally, contain monomeric PSII as well as a significant fraction of dimeric holocomplexes that identify this membrane area as the PSII repair zone. This structural organization and the heterogeneous PSII distribution support the idea that the stacking of thylakoid membranes leads to a division of labor that establishes distinct membrane areas with specific functions. |
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Keywords: | fractionation grana thylakoid photosynthesis photosystem II thylakoid membrane |
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