Localization of nitric-oxide synthase in plant peroxisomes |
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Authors: | Barroso J B Corpas F J Carreras A Sandalio L M Valderrama R Palma J M Lupiáñez J A del Río L A |
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Affiliation: | Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Experimentales, Universidad de Jaén, Paraje "Las Lagunillas" s/n, E-23071 Jaén, Spain. |
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Abstract: | The presence of nitric-oxide synthase (NOS) in peroxisomes from leaves of pea plants (Pisum sativum L.) was studied. Plant organelles were purified by differential and sucrose density gradient centrifugation. In purified intact peroxisomes a Ca(2+)-dependent NOS activity of 5.61 nmol of L-[(3)H]citrulline mg(-1) protein min(-1) was measured while no activity was detected in mitochondria. The peroxisomal NOS activity was clearly inhibited (60-90%) by different well characterized inhibitors of mammalian NO synthases. The immunoblot analysis of peroxisomes with a polyclonal antibody against the C terminus region of murine iNOS revealed an immunoreactive protein of 130 kDa. Electron microscopy immunogold-labeling confirmed the subcellular localization of NOS in the matrix of peroxisomes as well as in chloroplasts. The presence of NOS in peroxisomes suggests that these oxidative organelles are a cellular source of nitric oxide (NO) and implies new roles for peroxisomes in the cellular signal transduction mechanisms. |
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