title: Three-dimensional electron microscopy of the photosystem II core complex.
abstract: A three-dimensional image of the spinach photosystem II core complex composed of CP47, D1, D2, cytochrome b-559, and psbI gene product was reconstructed at 20-A resolution from the two-dimensional crystals negatively stained with phosphotungstate. Confirming the previous proposal, the crystal had a p22121 symmetry. One PSII core complex was measured to be 80 x 80 A in the membrane plane and 88 A normal to it. The mass distribution was asymmetric about the lipid bilayer, consistent with predictions from the amino acid sequences. The lumenal mass consisted of three domains forming a characteristic triangular platform with another domain on top of it. Three stromal domains were smaller and linearly arranged. Due to strong stain exclusion in the hydrophobic core part of the lipid bilayer, the transmembrane region appeared to be imaged with a reversed contrast. Inverting the contrast resulted in a reasonable density distribution for that part. Thus, though the information on the transmembrane region is limited, the domain structure of the PSII core complex was revealed and allowed us to propose a model for the arrangement of subunits in the PSII core complex.
authors.affiliation: Photosynthesis Research Laboratory, The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama, 351-01, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Mayanagi
authors.forename: T
authors.initials: T
authors.lastname: Ishikawa
authors.forename: C
authors.initials: C
authors.lastname: Toyoshima
authors.forename: Y
authors.initials: Y
authors.lastname: Inoue
authors.forename: K
authors.initials: K
authors.lastname: Nakazato
mesh_terms: D003460:Crystallization; D003461:Crystallography; D008051:Lipid Bilayers; D008565:Membrane Proteins / Q000648:ultrastructure; D008854:Microscopy, Electron; D008958:Models, Molecular; D010772:Phosphotungstic Acid / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins / Q000648:ultrastructure*; D045332:Photosystem II Protein Complex; D010940:Plant Proteins / Q000648:ultrastructure; D018724:Spinacia oleracea / Q000648:ultrastructure*
chemical_list: D008051:Lipid Bilayers; D008565:Membrane Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D010772:Phosphotungstic Acid