Arrangement of Photosystem II and ATP Synthase in Chloroplast Membranes of Spinach and Pea

摘要: We used cryoelectron tomography to reveal the arrangements of photosystem II (PSII) and ATP synthase in vitreous sections intact chloroplasts plunge-frozen suspensions isolated thylakoid membranes. found that stroma grana thylakoids are connected at margins by staggered lamellar membrane protrusions. The stacking repeat membranes frozen-hydrated is 15.7 nm, with a 4.5-nm lumenal space 3.2-nm distance between flat stromal surfaces. chloroplast confined minimally curved regions end lamellae, where it covers 20% surface area. In total, 85% synthases monomers remainder form random assemblies two or more copies. Supercomplexes PSII light-harvesting complex (LHCII) occasionally ordered arrays appressed thylakoids, whereas this order lost destacked arrays, each on either side gap contains two-dimensional crystal supercomplexes, lattices arranged such cores, LHCII trimers, minor LHCs face same kind opposite membrane. Grana formation likely result from electrostatic interactions these complexes across gap.