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Three-dimensional electron microscopy of the photosystem II core complex
K Mayanagi1, T Ishikawa, C Toyoshima
1Photosynthesis Research Laboratory, The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama, 351-01, Japan.
Journal of Structural Biology
|January 8, 1999
Summary
Researchers visualized the spinach photosystem II core complex using 3D imaging. This revealed the domain structure and subunit arrangement of this vital photosynthetic protein complex.
Area of Science:
- Biochemistry
- Structural Biology
- Photosynthesis Research
Background:
- Photosystem II (PSII) is crucial for oxygenic photosynthesis.
- Understanding the structure of the PSII core complex is key to elucidating its function.
- Previous models proposed subunit arrangements, but lacked high-resolution structural data.
Purpose of the Study:
- To reconstruct a three-dimensional image of the spinach photosystem II core complex.
- To determine the arrangement of subunits within the PSII core complex.
- To propose a structural model based on the obtained image.
Main Methods:
- Negative staining electron microscopy of two-dimensional crystals.
- 3D image reconstruction at 20-Å resolution.
- Analysis of mass distribution and domain structure.
Main Results:
- A 3D image of the spinach PSII core complex (CP47, D1, D2, cytochrome b-559, psbI) was obtained.
- The complex measured 80 x 80 Å in-plane and 88 Å normal to the membrane.
- Asymmetric mass distribution was observed, with distinct lumenal and stromal domains.
Conclusions:
- The study revealed the domain structure of the PSII core complex.
- A model for the arrangement of subunits within the PSII core complex was proposed.
- The findings provide insights into the structural organization of a key photosynthetic protein complex.