title: Localization of nitric-oxide synthase in plant peroxisomes.
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.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Experimentales, Universidad de Jaén, Paraje "Las Lagunillas" s/n, E-23071 Jaén, Spain.
authors.forename: J B
authors.initials: JB
authors.lastname: Barroso
authors.forename: F J
authors.initials: FJ
authors.lastname: Corpas
authors.forename: A
authors.initials: A
authors.lastname: Carreras
authors.forename: L M
authors.initials: LM
authors.lastname: Sandalio
authors.forename: R
authors.initials: R
authors.lastname: Valderrama
authors.forename: J M
authors.initials: JM
authors.lastname: Palma
authors.forename: J A
authors.initials: JA
authors.lastname: Lupiáñez
authors.forename: L A
authors.initials: LA
authors.lastname: del Río
mesh_terms: D019001:Nitric Oxide Synthase / Q000302:isolation & purification / Q000378:metabolism*; D020675:Peroxisomes / Q000378:metabolism*; D010944:Plants / Q000201:enzymology* / Q000648:ultrastructure
chemical_list: D019001:Nitric Oxide Synthase