First nitric oxide synthase (NOS) identified in cyanobacteria: the NOS from Synechococcus PCC 7335

CORREA ARAGUNDE NATALIA; FORESI, NOELIA PAMELA; LAMATTINA LORENZO

Mendoza

Congreso; XLVIII Reunión Anual SAIB; 2012

SAIB

Nitric oxide (NO) is a free radical involved in several physiological processes in all living organisms. NO is synthesized by nitric oxide synthases (NOS) from the substrate L-arginine (L-Arg). In most plants and cyanobacteria, canonical NOS enzymes are lacking, and NO is synthesized by other enzymatic and non-enzymatic pathways. Recently, our lab characterized the first NOS from the green marine algae Ostreococcus tauri (OtNOS), a member of the plant kingdom (Foresi et al, 2010). Later, through bioinformatic analysis we found a sequence coding for putative NOS in the cyanobacteria Synechococcus PCC 7335 (SyNOS). SyNOS has high similarity with OtNOS. SyNOS contains the two oxygenase and reductase domains as mammalian NOSs do and an extra globin domain in the N-terminal. The NO production in Synechococcus PCC 7335 was studied using the NO specific fluorescent probe DAF-2FM DA. The addition of the L-Arg induces the production of NO in a dose dependent manner. The exposure of a Synechococcus PCC 7335 to UV-B radiation causes an induction of 2-fold of NO release indicating a putative function of NOS-derived NO in responses to UV-B. The full length of SyNOS was cloned and expressed in E. coli. The characterization of the biochemical and structural properties of SyNOS is in progress.