title: Irreversible photoinhibition of photosystem II is caused by exposure of Synechocystis cells to strong light for a prolonged period.
abstract: Irreversible photoinhibition of photosystem II (PSII) occurred when Synechocystis sp. PCC 6803 cells were exposed to very strong light for a prolonged period. When wild-type cells were illuminated at 20 degrees C for 2 h with light at an intensity of 2,500 micromol photons m(-2) s(-1), the oxygen-evolving activity of PSII was almost entirely and irreversibly lost, whereas the photochemical reaction center in PSII was inactivated only reversibly. The extent of irreversible photoinhibition was enhanced at lower temperatures and by the genetically engineered rigidification of membrane lipids. Western and Northern blotting demonstrated that, after cells had undergone irreversible photoinhibition, the precursor to D1 protein in PSII was synthesized but not processed properly. These observations may suggest that exposure of Synechocystis cells to strong light results in the irreversible photoinhibition of the oxygen-evolving activity of PSII via impairment of the processing of pre-D1 and that this effect of strong light is enhanced by the rigidification of membrane lipids.
authors.affiliation: National Institute for Basic Biology, Myodaiji, Okazaki 444-8585, Japan.
authors.forename: Suleyman I
authors.initials: SI
authors.lastname: Allakhverdiev
authors.forename: Nelly
authors.initials: N
authors.lastname: Tsvetkova
authors.forename: Prasanna
authors.initials: P
authors.lastname: Mohanty
authors.forename: Balász
authors.initials: B
authors.lastname: Szalontai
authors.forename: Byoung Yong
authors.initials: BY
authors.lastname: Moon
authors.forename: Mónika
authors.initials: M
authors.lastname: Debreczeny
authors.forename: Norio
authors.initials: N
authors.lastname: Murata
mesh_terms: D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000737:chemistry / Q000378:metabolism; D008027:Light; D008563:Membrane Lipids / Q000737:chemistry / Q000378:metabolism; D009154:Mutation; D010788:Photosynthesis / Q000502:physiology; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D017550:Spectroscopy, Fourier Transform Infrared; D046939:Synechocystis / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D013696:Temperature
chemical_list: D005231:Fatty Acids, Unsaturated; D008563:Membrane Lipids; D045332:Photosystem II Protein Complex; D011498:Protein Precursors; C422369:photosystem II, psbA subunit