title: CyAbrB2 Contributes to the Transcriptional Regulation of Low CO2 Acclimation in Synechocystis sp. PCC 6803.
abstract: Acclimation to low CO2conditions in cyanobacteria involves the co-ordinated regulation of genes mainly encoding components of the carbon-concentrating mechanism (CCM). Making use of several independent microarray data sets, a core set of CO2-regulated genes was defined for the model strain Synechocystis sp. PCC 6803. On the transcriptional level, the CCM is mainly regulated by the well-characterized transcriptional regulators NdhR (= CcmR) and CmpR. However, the role of an additional regulatory protein, namely cyAbrB2 belonging to the widely distributed AbrB regulator family that was originally characterized in the genus Bacillus, is less defined. Here we present results of transcriptomic and metabolic profiling of the wild type and a ΔcyabrB2 mutant of Synechocystis sp. PCC 6803 after shifts from high CO2(5% in air, HC) to low CO2(0.04%, LC). Evaluation of the transcriptomic data revealed that cyAbrB2 is involved in the regulation of several CCM-related genes such as sbtA/B, ndhF3/ndhD3/cupA and cmpABCD under LC conditions, but apparently acts supplementary to NdhR and CmpR. Under HC conditions, cyAbrB2 deletion affects the transcript abundance of PSII subunits, light-harvesting components and Calvin-Benson-Bassham cycle enzymes. These changes are also reflected by down-regulation of primary metabolite pools. The data suggest a role for cyAbrB2 in adjusting primary carbon and nitrogen metabolism to photosynthetic activity under fluctuating environmental conditions. The findings were integrated into the current knowledge about the acquisition of inorganic carbon (Ci), the CCM and parts of its regulation on the transcriptional level.
authors.affiliation: Max-Planck-Institute of Molecular Plant Physiology, Department of Molecular Physiology: Applied Metabolome Analysis, Potsdam-Golm, Germany.
authors.forename: Isabel
authors.initials: I
authors.lastname: Orf
authors.affiliation: Plant Physiology Department, Institute of Biological Sciences, University of Rostock, Rostock, Germany.
authors.forename: Doreen
authors.initials: D
authors.lastname: Schwarz
authors.affiliation: Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, Israel.
authors.forename: Aaron
authors.initials: A
authors.lastname: Kaplan
authors.affiliation: Max-Planck-Institute of Molecular Plant Physiology, Department of Molecular Physiology: Applied Metabolome Analysis, Potsdam-Golm, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Kopka
authors.affiliation: Genetics & Experimental Bioinformatics, Institute of Biology III, University of Freiburg, Freiburg, Germany.
authors.forename: Wolfgang R
authors.initials: WR
authors.lastname: Hess
authors.affiliation: Plant Physiology Department, Institute of Biological Sciences, University of Rostock, Rostock, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Hagemann
authors.affiliation: Genetics & Experimental Bioinformatics, Institute of Biology III, University of Freiburg, Freiburg, Germany stephan.klaehn@biologie.uni-freiburg.de.
authors.forename: Stephan
authors.initials: S
authors.lastname: Klähn
mesh_terms: D000064:Acclimatization / Q000187:drug effects*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002245:Carbon Dioxide / Q000494:pharmacology*; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D005798:Genes, Bacterial; D007287:Inorganic Chemicals / Q000494:pharmacology; D055442:Metabolome / Q000187:drug effects / Q000235:genetics; D009154:Mutation / Q000235:genetics; D016366:Open Reading Frames / Q000235:genetics; D045332:Photosystem II Protein Complex / Q000378:metabolism; D046939:Synechocystis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D007287:Inorganic Chemicals; D045332:Photosystem II Protein Complex; D002245:Carbon Dioxide
keywords: 
  Synechocystis
  ; Carbon-concentrating mechanism; Low CO2 acclimation; Primary metabolism; Transcriptional regulation