Project description:Transcriptional profiling of WT, cytosolic ascorbate peroxidase 1 (Apx1) and peroxisomal catalase 2 (Cat2) single mutants and apx1/cat2 double mutant plants, subjected to 0h and 1h of high light irradiation in order to identify molecular mechanisms underlying the observed growth retardation and stress resistance of apx1/cat2 double mutant plants.
Project description:Transcriptional profiling of WT, cytosolic ascorbate peroxidase 1 (Apx1) and peroxisomal catalase 2 (Cat2) single mutants and apx1/cat2 double mutant plants, subjected to 0h and 1h of high light irradiation in order to identify molecular mechanisms underlying the observed growth retardation and stress resistance of apx1/cat2 double mutant plants. 4 genotypes x 2 conditions experiment including WT, apx1, cat2, and apx1/cat2 plants treated with 0h and 1h of high light irradiation. Two biological replicates. In total, 16 samples hybridized on 8 Arabidopsis Gene Expression microarrays V3 (Agilent, two-color array) including color swap of replicate samples.
Project description:Hydrogen peroxide (H2O2) can act as a signaling molecule that influences various aspects of plant growth and development, including stress signaling and cell death. To unravel the molecular mechanisms that regulate the response towards an impact of increased H2O2 levels in plant cells, we focused on the photorespiration-dependent peroxisomal H2O2 production in Arabidopsis thaliana mutants lacking CATALASE2 (CAT2) activity (cat2-2) and screened for second-site mutations that attenuate the Fv'/Fm' decrease and lesion formation linked to the cat2-2 phenotype. A mutation in GLYCOLATE OXIDASE 1, encoding one of the two photorespiratory isoforms of glycolate oxidase rescued the cell death phenotype of cat2-2 plants under photorespiration-promoting conditions. Interestingly, introduction of gox2 into the cat2 background did not have the same effect and the double cat2 gox2 mutants were as affected as the parental cat2 mutants under conditions promoting photorespiration. Using a series of physiological, biochemical and metabolomic approaches we investigated the differential photorespiratory response of cat2 mutants underlied by the lack of GOX1 and GOX2. These differences are in line with the non-redundant functions of GOX1 and GOX2 which could be observed under enhanced photorespiration.
Project description:Reactive oxygen species (ROS) are central regulators of plant growth and stress responses, and their cellular levels are tightly controlled by antioxidant systems, including the evolutionarily conserved catalases that decompose hydrogen peroxide (H2O2) predominantly within peroxisomes and glyoxysomes. Despite their importance, key aspects of catalase biogenesis, regulation, subcellular targeting, and potential extra-peroxisomal functions remain poorly understood. Using affinity purification of the UV-B photoreceptor UVR8 coupled with mass spectrometry, we identified a REGULATOR OF CHROMATIN CONDENSATION 1–like protein in Arabidopsis, which we named CATALASE-INTERACTING RCC1-LIKE 1 (CAIR1). CAIR1 interacts with all three catalase isoforms (CAT1–CAT3) as well as their chaperone NO CATALASE ACTIVITY 1 (NCA1). Loss-of-function cair1 mutants partially phenocopy cat2 and nca1, exhibiting reduced catalase activity, enhanced sensitivity to oxidative stress and alkaline growth conditions, and impaired primary root elongation. Mechanistically, cytosolic interaction between CAIR1 and CAT2 enhances total cellular catalase activity by facilitating peroxisomal import and proper subcellular localization of CAT2. In the absence of CAIR1, CAT2 forms aggregates, likely accounting for the observed loss of catalase activity. Notably, CAIR1 undergoes reversible, redox-dependent oligomerization that strengthens its interaction with catalases. Mutation of CAIR1 at Cys-356 and Cys-545 compromises this interaction under elevated ROS conditions and fails to rescue the oxidative stress sensitivity of cair1 mutants. Moreover, UV-B exposure suppresses catalase activity by weakening the interaction between CAIR1 and catalases, linking environmental light signaling to cellular redox regulation. Together, our findings reveal CAIR1 as a dynamic redox-responsive regulator of catalase activity that maintains cellular redox homeostasis by coordinating catalase localization and function through reversible oligomerization.
Project description:Hydrogen peroxide (H2O2) can act as a signaling molecule that influences various aspects of plant growth and development, including stress signaling and cell death. To unravel the molecular mechanisms that regulate the response towards an impact of increased H2O2 levels in plant cells, we focused on the photorespiration-dependent peroxisomal H2O2 production in Arabidopsis thaliana mutants lacking CATALASE2 (CAT2) activity (cat2-2) and screened for second-site mutations that attenuate the Fv'/Fm' decrease and lesion formation linked to the cat2-2 phenotype. A mutation in GLYCOLATE OXIDASE 1, encoding one of the two photorespiratory isoforms of glycolate oxidase rescued the cell death phenotype of cat2-2 plants under photorespiration-promoting conditions. Interestingly, introduction of gox2 into the cat2 background did not have the same effect and the double cat2 gox2 mutants were as affected as the parental cat2 mutants under conditions promoting photorespiration. Using a series of physiological, biochemical and metabolomic approaches we investigated the differential photorespiratory response of cat2 mutants underlied by the lack of GOX1 and GOX2. These differences are in line with the non-redundant functions of GOX1 and GOX2 which could be observed under enhanced photorespiration. Unstressed and stressed samples of cat2 gox1 and cat2 gox2 double mutants in triplicate
Project description:Hydrogen peroxide (H2O2) can act as a signaling molecule that influences various aspects of plant growth and development, including stress signaling and cell death. Catalase deficient plants are pioneering systems which accumulate hydrogen peroxide (H2O2) from peroxisomal origin during photorespiratory challenges. Respiratory burst oxidase homologues D and F are known to participate in intracellular oxidative stress response launched in cat2 mutants (Chaouch et al., 2012). We studied the compared the transcriptional response of cat2 rbohD and cat2 rbohF double mutants versus the cat2 background to further adress their role during photorespiratory stress.
Project description:Hydrogen peroxide (H2O2) can act as a signaling molecule that influences various aspects of plant growth and development, including stress signaling and cell death. To unravel the molecular mechanisms that regulate the response towards an impact of increased H2O2 levels in plant cells, we focused on the photorespiration-dependent peroxisomal H2O2 production in Arabidopsis thaliana mutants lacking CATALASE2 (CAT2) activity (cat2-2).
Project description:Hydrogen peroxide (H2O2) can act as a signaling molecule that influences various aspects of plant growth and development, including stress signaling and cell death. To unravel the molecular mechanisms that regulate the response towards an impact of increased H2O2 levels in plant cells, we focused on the photorespiration-dependent peroxisomal H2O2 production in Arabidopsis thaliana mutants lacking CATALASE2 (CAT2) activity (cat2-2). Unstressed and stressed samples of cat2-2 in triplicate
Project description:Hydrogen peroxide (H2O2) can act as a signaling molecule that influences various aspects of plant growth and development, including stress signaling and cell death. To unravel the molecular mechanisms that regulate the response towards an impact of increased H2O2 levels in plant cells, we focused on the photorespiration-dependent peroxisomal H2O2 production in Arabidopsis thaliana mutants lacking CATALASE2 (CAT2) activity (cat2-2) and screened for second-site mutations that attenuate the Fv'/Fm' decrease and lesion formation linked to the cat2-2 phenotype. A mutation in the transcriptional regulator SHORT-ROOT (SHR) of the GRAS family rescued the cell death phenotype of cat2-2 plants under photorespiration-promoting conditions in a SCR-independent way, and provoked perturbation of photorespiratory metabolites. SHR deficiency boosted ascorbate levels and prevented the oxidation of the glutathione pool in cat2-2 background upon exposure to photorespiratory stress. These results reveal an unanticipated role for SHR as a regulator of cellular redox homeostasis.
Project description:Hydrogen peroxide (H2O2) can act as a signaling molecule that influences various aspects of plant growth and development, including stress signaling and cell death. Catalase deficient plants are pioneering systems which accumulate hydrogen peroxide (H2O2) from peroxisomal origin during photorespiratory challenges. Respiratory burst oxidase homologues D and F are known to participate in intracellular oxidative stress response launched in cat2 mutants (Chaouch et al., 2012). We studied the compared the transcriptional response of cat2 rbohD and cat2 rbohF double mutants versus the cat2 background to further adress their role during photorespiratory stress. After 3 weeks of growth, leaf tissue from the three different genotypes was harvested in triplicate.