title: Effects of high light on transcripts of stress-associated genes for the cyanobacteria Synechocystis sp. PCC 6803 and Prochlorococcus MED4 and MIT9313.
abstract: Cyanobacteria constitute an ancient, diverse and ecologically important bacterial group. The responses of these organisms to light and nutrient conditions are finely controlled, enabling the cells to survive a range of environmental conditions. In particular, it is important to understand how cyanobacteria acclimate to the absorption of excess excitation energy and how stress-associated transcripts accumulate following transfer of cells from low- to high-intensity light. In this study, quantitative RT-PCR was used to monitor changes in levels of transcripts encoding chaperones and stress-associated proteases in three cyanobacterial strains that inhabit different ecological niches: the freshwater strain Synechocystis sp. PCC 6803, the marine high-light-adapted strain Prochlorococcus MED4 and the marine low-light-adapted strain Prochlorococcus MIT9313. Levels of transcripts encoding stress-associated proteins were very sensitive to changes in light intensity in all of these organisms, although there were significant differences in the degree and kinetics of transcript accumulation. A specific set of genes that seemed to be associated with high-light adaptation (groEL/groES, dnaK2, dnaJ3, clpB1 and clpP1) could be targeted for more detailed studies in the future. Furthermore, the strongest responses were observed in Prochlorococcus MED4, a strain characteristic of the open ocean surface layer, where hsp genes could play a critical role in cell survival.
authors.affiliation: Station Biologique, UMR 7127, CNRS et Université Pierre et Marie Curie, BP 74, F-29682 Roscoff cedex, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Mary
authors.affiliation: Carnegie Institution of Washington, Department of Plant Biology, 260 Panama Street, Stanford, CA 94305, USA.
authors.forename: Chao-Jung
authors.initials: CJ
authors.lastname: Tu
authors.affiliation: Carnegie Institution of Washington, Department of Plant Biology, 260 Panama Street, Stanford, CA 94305, USA.
authors.forename: Arthur
authors.initials: A
authors.lastname: Grossman
authors.affiliation: Station Biologique, UMR 7127, CNRS et Université Pierre et Marie Curie, BP 74, F-29682 Roscoff cedex, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Vaulot
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D000458:Cyanobacteria / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism; D005618:Fresh Water / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D018869:Heat-Shock Response; D008027:Light; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012623:Seawater / Q000382:microbiology; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D010450:Endopeptidases