title: Strong-light photoinhibition treatment accelerates the changes of protein secondary structures in triton-treated photosystem I and photosystem II complexes.
abstract: Changes in the protein secondary structure and electron transport activity of the Triton X-100-treated photosystem I (PSI) and photosystem II (PSII) complexes after strong illumination treatment were studied using Fourier transform-infrared (FT-IR) spectroscopy and an oxygen electrode. Short periods of photoinhibitory treatment led to obvious decreases in the rates of PSI-mediated electron transport activity and PSII-mediated oxygen evolution in the native or Triton-treated PSI and PSII complexes. In the native PSI and PSII complexes, the protein secondary structures had little changes after the photoinhibitory treatment. However, in both Triton-treated PSI and PSII complexes, short photoinhibition times caused significant loss of alpha-helical content and increase of beta-sheet structure, similar to the conformational changes in samples of Triton-treated PSI and PSII complexes after long periods of dark incubation. Our results demonstrate that strong-light treatment to the Triton-treated PSI and PSII complexes accelerates destruction of the transmembrane structure of proteins in the two photosynthetic membranes.
authors.affiliation: Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing, China.
authors.forename: X
authors.initials: X
authors.lastname: Ruan
authors.forename: Q
authors.initials: Q
authors.lastname: Xu
authors.forename: H B
authors.initials: HB
authors.lastname: Mao
authors.forename: G F
authors.initials: GF
authors.lastname: Li
authors.forename: J
authors.initials: J
authors.lastname: Wei
authors.forename: Y D
authors.initials: YD
authors.lastname: Gong
authors.forename: T Y
authors.initials: TY
authors.lastname: Kuang
authors.forename: N M
authors.initials: NM
authors.lastname: Zhao
mesh_terms: D004579:Electron Transport; D008027:Light; D017830:Octoxynol / Q000737:chemistry*; D010100:Oxygen / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D018515:Plant Leaves / Q000737:chemistry / Q000502:physiology; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared; D018724:Spinacia oleracea / Q000737:chemistry / Q000502:physiology
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D017830:Octoxynol; D010100:Oxygen