Calmodulin antagonist affects peroxisomal functionality by disrupting both peroxisomal Ca2+and protein import.
Ca2+is a second messenger in many physiological and phytopathological processes. Peroxisomes are subcellular compartments with an active oxidative and nitrosative metabolism. Previous studies have demonstrated that peroxisomal nitric oxide (NO) generation is dependent on Ca2+and calmodulin (CaM). Here, we usedArabidopsis thalianatransgenic seedlings expressing cyan fluorescent protein (CFP) containing a type 1 peroxisomal-targeting signal motif (PTS1; CFP-PTS1), which enables peroxisomes to be visualizedin vivo, and also used a cell-permeable fluorescent probe for Ca2+Analysis by confocal laser-scanning microscopy (CLSM) enabled us to visualize the presence of endogenous Ca2+in the peroxisomes of both roots and guard cells. The presence of Ca2+in peroxisomes and the import of CFP-PTS1 are drastically disrupted by both CaM antagonist and glutathione (GSH). Furthermore, the activity of three peroxisomal enzymes (catalase, glycolate oxidase and hydroxypyruvate reductase) containing PTS1 was clearly affected in these conditions, with a decrease of between 41 and 51%. In summary, data show that Ca2+and CaM are strictly necessary for protein import and normal functionality of peroxisomal enzymes, including antioxidant and photorespiratory enzymes, as well as for NO production.
Group of Antioxidants, Free Radicals and Nitric Oxide in Biotechnology, Food and Agriculture, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, CSIC, C/Profesor Albareda 1, Granada E-18008, Spain javier.corpas@eez.csic.es.
Francisco J
0000-0002-1814-9212
FJ
Corpas
Group of Biochemistry and Cell Signaling in Nitric Oxide, Department of Biochemistry and Molecular Biology, Campus 'Las Lagunillas', University of Jaén, Jaén E-23071, Spain.
Juan B
JB
Barroso
D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005978:Glutathione / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology; D020675:Peroxisomes / Q000187:drug effects / Q000378:metabolism*; D059828:Plant Cells / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects
D029681:Arabidopsis Proteins; D002147:Calmodulin; D009569:Nitric Oxide; D005978:Glutathione; D002118:Calcium
Ca2+; Calmodulin; Catalase; Glutathione; Nitric oxide; Peroxisome