title: Alpha-tocopherol is essential for acquired chill-light tolerance in the cyanobacterium Synechocystis sp. strain PCC 6803.
abstract: Unlike Escherichia coli, the cyanobacterium Synechocystis sp. strain PCC 6803 is insensitive to chill (5 degrees C) in the dark but rapidly losses viability when exposed to chill in the light (100 micromol photons m(-2) s(-1)). Preconditioning at a low temperature (15 degrees C) greatly enhances the chill-light tolerance of Synechocystis sp. strain PCC 6803. This phenomenon is called acquired chill-light tolerance (ACLT). Preconditioned wild-type cells maintained a substantially higher level of alpha-tocopherol after exposure to chill-light stress. Mutants unable to synthesize alpha-tocopherol, such as slr1736, slr1737, slr0089, and slr0090 mutants, almost completely lost ACLT. When exposed to chill without light, these mutants showed no or a slight difference from the wild type. When complemented, the slr0089 mutant regained its ACLT. Copper-regulated expression of slr0090 from P(petE) controlled the level of alpha-tocopherol and ACLT. We conclude that alpha-tocopherol is essential for ACLT of Synechocystis sp. strain PCC 6803. The role of alpha-tocopherol in ACLT may be based largely on a nonantioxidant activity that is not possessed by other tocopherols or pathway intermediates.
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, People's Republic of China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.forename: Chuntao
authors.initials: C
authors.lastname: Yin
authors.forename: Weizhi
authors.initials: W
authors.lastname: Li
authors.forename: Xudong
authors.initials: X
authors.lastname: Xu
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000528:radiation effects; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003080:Cold Temperature; D003300:Copper / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000528:radiation effects; D008027:Light; D008054:Lipid Peroxides / Q000378:metabolism; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism; D008957:Models, Genetic; D009154:Mutation; D046939:Synechocystis / Q000235:genetics / Q000378:metabolism*; D013696:Temperature; D024502:alpha-Tocopherol / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008054:Lipid Peroxides; D003300:Copper; D008780:Methyltransferases; C047259:gamma-tocopherol methyltransferase; D024502:alpha-Tocopherol