Characterization of a Nitric Oxide Synthase from the Plant Kingdom: NO Generation from the Green Alga Ostreococcus tauri Is Light Irradiance and Growth Phase Dependent    

Abstract

The search for a nitric oxide synthase (NOS) sequence in the plant kingdom yielded two sequences from the recently published genomes of two green algae species of the Ostreococcus genus, O. tauri and O. lucimarinus. In this study, we characterized the sequence, protein structure, phylogeny, biochemistry, and expression of NOS from O. tauri. The amino acid sequence of O. tauri NOS was found to be 45% similar to that of human NOS. Folding assignment methods showed that O. tauri NOS can fold as the human endothelial NOS isoform. Phylogenetic analysis revealed that O. tauri NOS clusters together with putative NOS sequences of a Synechoccocus sp strain and Physarum polycephalum. This cluster appears as an outgroup of NOS representatives from metazoa. Purified recombinant O. tauri NOS has a K m for the substrate L-Arg of 12 6 5 mM. Escherichia coli cells expressing recombinant O. tauri NOS have increased levels of NO and cell viability. O. tauri cultures in the exponential growth phase produce 3-fold more NOS-dependent NO than do those in the stationary phase. In O. tauri, NO production increases in high intensity light irradiation and upon addition of L-Arg, suggesting a link between NOS activity and microalgal physiology.

Sulfur deprivation-induced expression of THB1, a Chlamydomonas reinhardtii truncated hemoglobin, is mediated by nitrate reductase-dependent NO production

“…Given that NO is generated in S-deprived cells (Minaeva et al, 2017), the increase in THB1 transcription detected during S limitation may reflect NOS activity. Recently, several algae were shown to contain NOS (Foresi et al, 2010;Jeandroz et al, 2016). This, however, did not appear to be the case in our experiments.…”

Nitric Oxide and ProteinS-Nitrosylation Are Integral to Hydrogen Peroxide-Induced Leaf Cell Death in Rice

“…To date, numerous potential sources for NO production have been described in plants (Gupta et al, 2011), including a nitric oxide synthase (NOS)-like activity (Delledonne et al, 1998;Durner et al, 1998;BessonBard et al, 2008), nitrate reductase (NR; Stöhr and Stremlau, 2006;Stoimenova et al, 2007;Seligman et al, 2008), xanthine oxidoreductase (Corpas et al, 2008), and polyamine/hydroxylamine-mediated NO production (Rü mer et al, 2009). Archetypal NOS enzymes found in animals (Palmer et al, 1988;Knowles and Moncada, 1994) and also the green alga Ostreococcus tauri (Foresi et al, 2010) catalyze the NADPH-dependent oxidation of L-Arg, producing L-citrulline and NO. A similar activity has been reported in higher plants, which is blunted by classical mammalian NOS inhibitors (Delledonne et al, 1998;Durner et al, 1998;Jasid et al, 2006;Vandelle and Delledonne, 2008;Corpas et al, 2009).…”

Le monoxyde d’azote

“…Lors de l'établissement de la RH, les cellules qui n'ont pas été en contact avec la cryptogéine (tissus adjacents à la zone nécrotique ou distants de celle-ci) sont placées dans un état de veille défensive permettant à la plante de résister efficacement à une attaque ultérieure par Phytophthora cryptogea ou d'autres agents pathogènes. [7]. En revanche, dans les génomes des plantes terrestres séquencés à ce jour, aucun gène possédant une identité de séquence avec les gènes animaux codant pour les NOS n'a pu être identifié.…”