First characterization of a Nitric Oxide Synthase from the plant kingdom.

NOELIA FORESI, NATALIA CORREA-ARAGUNDE AND LORENZO LAMATTINA

San Miguel de Tucumán, Argentina,

Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular; 2009

Sociedad Argentina de Investigacion en Bioquimica y Biologia Molecular

Recently, it has been completed the genome sequence of the unicellular green algae Ostreococcus tauri (Ot), the smallest member of the plant Kingdom. In the genome of Ot it has been identified a gene sharing high similarity with those coding for nitric oxide synthase (NOS) of mammals. NOS enzymes generate nitric oxide (NO) from arginine using NADPH as electron donor. NO is involved in many physiological processes and associated with responses to (a) biotic stresses in organisms from all Kingdoms. To date, no gene sequence, cDNA or protein coding for a putative plant NOS have been found. In this study, we have conducted the cloning, expression and biochemical characterization of OtNOS. The OtNOS has been successfully expressed as a recombinant protein in Escherichia coli. OtNOS was showed as high-spin heme protein and shared spectral properties to those described for others isolated NOS. Activity of the recombinant OtNOS was determined by two methods (i) haemoglobin capture an (ii) NADPH oxidations. Bacteria expressing the recombinant OtNOS display high levels of NO after supplementation with the NOS substrate L-arginine and were more resistant than wt to oxidant hydrogen peroxide. All together, these results describe for the first time the presence of NOS in plant Kingdom.