Tokano Takaya, Kato Yuki, Sugiyama Shogo, Uchihashi Takayuki, Noguchi Takumi
Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
J Phys Chem B. 2020 Jul 16;124(28):5847-5857. doi: 10.1021/acs.jpcb.0c03892. Epub 2020 Jul 2.
Photosystem II (PSII) is a multiprotein complex that has a function of light-driven water oxidation. The catalytic site of water oxidation is the MnCaO cluster, which is bound to the lumenal side of PSII through amino acid residues from the D1 and CP43 proteins and is further surrounded by the extrinsic proteins. In this study, we have for the first time visualized the structural dynamics of the lumenal region of a PSII core complex using high-speed atomic force microscopy (HS-AFM). The HS-AFM images of a PSII membrane fragment showed stepwise dissociation of the PsbP and PsbO extrinsic proteins. Upon subsequent destruction of the MnCaO cluster, the lumenal domain of CP43 was found to undergo a conformational fluctuation. The observed structural flexibility and conformational fluctuation of the CP43 lumenal domain are suggested to play important roles in the biogenesis of PSII and the photoassembly of the MnCaO cluster.
光系统II（PSII）是一种具有光驱动水氧化功能的多蛋白复合物。水氧化的催化位点是MnCaO簇，它通过D1和CP43蛋白的氨基酸残基与PSII的腔侧结合，并进一步被外在蛋白包围。在本研究中，我们首次使用高速原子力显微镜（HS-AFM）可视化了PSII核心复合物腔区域的结构动力学。PSII膜片段的HS-AFM图像显示了PsbP和PsbO外在蛋白的逐步解离。在随后MnCaO簇被破坏后，发现CP43的腔结构域发生了构象波动。CP43腔结构域观察到的结构灵活性和构象波动被认为在PSII的生物合成和MnCaO簇的光组装中起重要作用。
