The light-harvesting core-complex and the B820-subunit from Rhodopseudomonas marina. Part II. Electron microscopic characterisation.
Electron micrographs of photosynthetic membranes of the BChla-containing bacterium Rp. marina showed a quasi-crystalline structure. The photoreceptor units are arranged in a hexagonal lattice with a reaction center to reaction center distance of 102 +/- 3 A. Purified B880-complex was concentrated up to an OD880 of 60 which induced the formation of large protein vesicles. The protein complexes within these vesicles were highly ordered and showed a hexagonal lattice with the same center to center distance of 102 +/- 3 A as was observed in the native membranes. Image processing of the micrographs revealed a ring-like structure of the B880-complex at 26 A resolution and suggests that the B880-complex consists of 5 or 6 subunits. For the first time it can be shown that an isolated core-complex is in a stable, ring-like structure even without the reaction center which is supposed to be located in the middle of the B880-ring. The data indicate that the isolated B880-complex exhibits the same structure as in the native membrane.
Meckenstock
R U
RU
Institut für Molekularbiologie und Biophysik, ETH-Hönggerberg, Zürich, Switzerland.
Krusche
K
K
Brunisholz
R A
RA
Zuber
H
H
D001429:Bacteriochlorophylls / Q000032:analysis; D003460:Crystallization; D005583:Fourier Analysis; D007091:Image Processing, Computer-Assisted; D007425:Intracellular Membranes / Q000648:ultrastructure; D045342:Light-Harvesting Protein Complexes; D008854:Microscopy, Electron; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000648:ultrastructure*; D012241:Rhodopseudomonas / Q000737:chemistry* / Q000648:ultrastructure
D001429:Bacteriochlorophylls; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins