Expression of nitric oxide synthases from photosynthetic microorganisms confers rapid adaptation to low nitrogen growth conditions in Escherichia coli.

CORREA ARAGUNDE NATALIA; FORESI NOELIA PAMELA; LAMATTINA LORENZO

Mar del Plata

Congreso; X Congreso Argentino de Microbiología General SAMIGE; 2014

Sociedad Argentina de Microbiología General SAMIGE

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). Our laboratory characterized a NOS from the marine unicellular algae Ostreococcus tauri (OtNOS, Foresi et al. 2010), the first NOS belonging to the plant kingdom. Later, through bioinformatics analysis we found a sequence coding for a putative NOS in another photosynthetic organism, the cyanobacteria Synechococcus PCC 7335 (SyNOS). The full length sequences of SyNOS and OtNOS were cloned and expressed in Escherichia coli. The recombinant proteins were detected in cells by western blotting after 2 h of induction with IPTG. Bacteria expressing the recombinant NOS in LB medium reach a higher OD at stationary phase than cells transformed with the empty vector (EV). The cell cultures expressing OtNOS and SyNOS genes show higher levels of NO production and, the expression of the NO-sensor hmp gene confirmed the increased levels of NO in the transformed bacteria. Additionally, cultures of E. coli expressing the recombinant OtNOS and SyNOS growing in deficient nitrogen (N) media display similar growth rates to those attained in sufficient N conditions. It is postulated the participation of NOS activity and its product NO, in the N metabolism of the bacteria. The molecular mechanism responsible for the NOS ability of conferring enhanced adaptation to N starvation is currently under study.