title: A reversible decrease in ribulose 1,5-bisphosphate carboxylase/oxygenase carboxylation activity caused by the aggregation of the enzyme's large subunit is triggered in response to the exposure of moderate irradiance-grown plants to low irradiance.
abstract: Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is highly regulated in response to fluctuations in the environment, including changes in irradiance. However, no complex data are available on Rubisco regulatory mechanisms triggered in plants which are submitted to moderate-low irradiance shift. Therefore, we investigated in a comprehensive way the changes at the level of amount of Rubisco protein, its structural organization and carboxylase activity of the holoenzyme as triggered by exposure of moderate irradiance-grown Arabidopsis thaliana plants to low irradiance conditions. An exposure of moderate irradiance-grown plants to low irradiance for a single photoperiod caused the exclusion of a certain pool of Rubisco under altered conditions owing to oxidative modifications resulting in the formation of protein aggregates involving Rubisco large subunit (LS). As a result, both initial and total Rubisco carboxylase activities were reduced, whereas Rubisco activation state remained largely unchanged. The results of the determination of reactive oxygen species indicated that a moderate/low irradiance transition had stimulated (1) O2 accumulation and we strongly suggest that Rubisco oxidative modifications leading to formation of aggregates encompassing Rubisco-LS were triggered by (1) O2 . When moderate irradiance regime was resumed, the majority of Rubisco-LS containing aggregates tended to be resolubilized, and this allowed Rubisco carboxylation activities to be largely recovered, without changes in the activation state of the enzyme. In the longer term, these results allow us to better understand a complexity of Rubisco regulatory mechanisms activated in response to abiotic stresses and during recovery from the stresses.
authors.affiliation: Department of Plant Physiology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, Poznań, 61 614, Poland.
authors.forename: Magda
authors.initials: M
authors.lastname: Grabsztunowicz
authors.affiliation: Department of Physical Chemistry, Institute of Chemistry & Technical Electrochemistry, University of Technology, Poznań, 60 965, Poland.
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Górski
authors.affiliation: Department of Plant Physiology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, Poznań, 61 614, Poland.
authors.forename: Robert
authors.initials: R
authors.lastname: Luciński
authors.affiliation: Department of Plant Physiology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, Poznań, 61 614, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Jackowski
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D002264:Carboxylic Acids / Q000378:metabolism*; D008027:Light; D018515:Plant Leaves / Q000528:radiation effects; D014176:Protein Biosynthesis; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D002264:Carboxylic Acids; D012273:Ribulose-Bisphosphate Carboxylase