title: Effect of phosphatidylglycerol on molecular organization of photosystem I.
abstract: Phosphatidylglycerol (PG) is the only anionic phospholipid in photosynthetic membrane. In this study, photosystem I (PSI) particles obtained from plant spinach were reconstituted into PG liposomes at a relatively high concentration. The results from visible absorption, fluorescence emission, and circular dichroism (CD) spectra reveal an existence of the interactions of PSI with PG. PG effect causes blue-shift and intensity decrease of Chl a peak bands in the absorption and 77 K fluorescence emission. The visible CD spectra indicate that the excitonic interactions for Chl a and Chl b molecules were enhanced upon reconstitution. Furthermore, more or less blue- or red-shift of the peaks characterized by Chl a, Chl b, and carotenoid molecules are also occurred. Simultaneously, an increase in alpha-helix and a decrease particularly in the disordered conformations of protein secondary structures are observed. In addition, the same effect also leads to somewhat more tryptophan (Trp) residues exposed to the polar environment. These results demonstrate that some alteration of molecular organization occurs within both the external antenna LHCI and PSI core complex after PSI reconstitution.
authors.affiliation: Key Laboratory of Photosynthesis and Environment Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, PR China. yangzhenle@hotmail.com
authors.forename: Zhenle
authors.initials: Z
authors.lastname: Yang
authors.forename: Xinhua
authors.initials: X
authors.lastname: Su
authors.forename: Feng
authors.initials: F
authors.lastname: Wu
authors.forename: Yandao
authors.initials: Y
authors.lastname: Gong
authors.forename: Tingyun
authors.initials: T
authors.lastname: Kuang
mesh_terms: D002942:Circular Dichroism; D008081:Liposomes / Q000737:chemistry; D010715:Phosphatidylglycerols / Q000737:chemistry / Q000494:pharmacology*; D045331:Photosystem I Protein Complex / Q000737:chemistry* / Q000187:drug effects*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D014364:Tryptophan / Q000737:chemistry
chemical_list: D008081:Liposomes; D010715:Phosphatidylglycerols; D045331:Photosystem I Protein Complex; D010936:Plant Extracts; D014364:Tryptophan