title: O2 reduction by photosystem I involves phylloquinone under steady-state illumination.
abstract: O2 reduction was investigated in photosystem I (PSI) complexes isolated from cyanobacteria Synechocystis sp. PCC 6803 wild type (WT) and menB mutant strain, which is unable to synthesize phylloquinone and contains plastoquinone at the quinone-binding site A1. PSI complexes from WT and menB mutant exhibited different dependencies of O2 reduction on light intensity, namely, the values of O2 reduction rate in WT did not reach saturation at high intensities, in contrast to the values in menB mutant. The obtained results suggest the immediate phylloquinone involvement in the light-induced O2 reduction by PSI.
authors.affiliation: Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Russia. Electronic address: kozuleva@gmail.com.
authors.forename: Marina A
authors.initials: MA
authors.lastname: Kozuleva
authors.affiliation: A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
authors.forename: Anastasia A
authors.initials: AA
authors.lastname: Petrova
authors.affiliation: Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Russia; A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
authors.forename: Mahir D
authors.initials: MD
authors.lastname: Mamedov
authors.affiliation: A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
authors.forename: Alexey Yu
authors.initials: AY
authors.lastname: Semenov
authors.affiliation: Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Russia.
authors.forename: Boris N
authors.initials: BN
authors.lastname: Ivanov
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D003067:Coenzymes / Q000737:chemistry / Q000378:metabolism; D004579:Electron Transport / Q000528:radiation effects; D055786:Gene Knockout Techniques; D008027:Light; D008958:Models, Molecular; D008968:Molecular Conformation; D009154:Mutation; D010100:Oxygen / Q000378:metabolism*; D045331:Photosystem I Protein Complex / Q000378:metabolism*; D046939:Synechocystis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D010837:Vitamin K 1 / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003067:Coenzymes; D045331:Photosystem I Protein Complex; D010837:Vitamin K 1; D010100:Oxygen
keywords: Electron transfer; Oxygen reduction; Photosynthesis; Photosystem I; Phylloquinone; Plastoquinone