Peroxynitrite (ONOO-) is endogenously produced in arabidopsis peroxisomes and is overproduced under cadmium stress.
OBJECTIVE
Peroxisomes are subcellular compartments involved in multiple cellular metabolic pathways. Peroxynitrite (ONOO(-)) is a nitric oxide-derived molecule which is a nitrating species that causes nitration of proteins. This study used cell biology techniques to explore the potential presence of peroxynitrite in peroxisomes and evaluated its content under stress conditions (excess cadmium).


METHODS
Peroxynitrite, nitric oxide and superoxide anion were studied using cell-permeable specific fluorescent probes by confocal laser scanning microscopy in Arabidopsis thaliana transgenic plants expressing cyan fluorescent protein through the addition of peroxisomal targeting signal 1 (PTS1), which enables peroxisomes to be visualized in vivo. Key Results When no stress was applied, peroxynitrite was clearly localized in the peroxisomes of roots and stomatal guard cells. Under cadmium (150 μm) stress, the generation of peroxynitrite, nitric oxide and the superoxide anion (O2(·-)) increased and was localized in peroxisomes and the cytosol, participating in the generation of nitro-oxidative stress.


CONCLUSIONS
The results show that peroxisomes are an endogenous source of peroxynitrite, which is over-produced under cadmium stress, suggesting that the metabolism of reactive nitrogen species in peroxisomes could participate in the mechanism of the response to this heavy metal.
Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín (EEZ), Consejo Superior de Investigaciones Científicas, E-18080 Granada, Spain.
Francisco J
FJ
Corpas
Juan B
JB
Barroso
D017360:Arabidopsis / Q000187:drug effects / Q000502:physiology*; D002104:Cadmium / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress; D020675:Peroxisomes / Q000187:drug effects / Q000378:metabolism*; D030421:Peroxynitrous Acid / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D030821:Plants, Genetically Modified; D013312:Stress, Physiological; D013481:Superoxides / Q000378:metabolism
D002104:Cadmium; D013481:Superoxides; D030421:Peroxynitrous Acid; D009569:Nitric Oxide
Arabidopsis thaliana; Nitric oxide; cadmium; heavy metal; nitrosative stress; peroxisomes; peroxynitrite; protein tyrosine nitration