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