Structure and dynamics of photosynthetic membrane-bound proteins in Rhodobacter Sphaeroides,studied with solid-state NMR spectroscopy |
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Authors: | Kikuchi Jun Williamson Michael P Shimada Keizo Asakura Tetsuo |
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Institution: | (1) Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184, Japan;(2) Present address: Genomic Sciences Center (GSC), The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-0198, Japan;(3) Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK;(4) Department of Biology, Tokyo Metropolitan University, Hachioji, Tokyo 183, Japan;(5) Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184, Japan |
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Abstract: | The photosynthetic purple bacteria such as Rb. sphaeroides possesses an intracytoplasmic membrane (ICM) and a variety of pigment-binding membrane proteins located in the ICM, acting
as photoreceptor. Such photosynthetic apparatus is concentrated in the ICM. It is composed of three multimeric membrane-bound
proteins; light-harvesting complexes (LH 1, LH 2), a reaction center (RC) and a cytochrome b/c1 complex. We have purified these membranes, which are called chromatophores, and characterized the structure and dynamics
of the photosynthetic membrane-bound proteins by means of multi-nuclear solid state NMR. First, the isotropic chemical shift
of carbonyl carbons in natural abundance and 1-13C] Phe labeled chromatophores indicates that the membrane-bound proteins take mainly the helical conformation. Second, the
chemical shifts of side-chain resonances of uniformly 15N-labeled chromatophores indicate the side-chain histidine residue is mainly hydrogen bonded, whereas structural heterogeneity
of arginine and lysine side-chains are probed by those wide distribution of 15N shifts. Thirdly, the β-2H3]Ala and ε-2H2]Tyr labeling of the chromatophores are performed and dynamics of the β-2H]Ala and the ε-2H2]Tyr labeled chromatophores are studied by means of 2H solid state NMR. The dynamics of β-2H3]Ala is found to be a 108Hz three-site jump motion with 10° liberation along the Cα-Cβ bond axis. The 2H-NMR powder pattern spectrum of ε-2H2] Tyr labeled chromatophores was interpreted with an averaged correlation time of 5×105 Hz with 180° two-fold flips, the result of the averaging of two kinds of split spectra in terms of motional time scale.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | magic angle spinning membrane protein dynamics membrane protein structure nuclear magnetic resonance photosynthetic purple bacteria quadrupole echo |
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