Structure diversity of nitric oxide synthases (NOS): the emergence of new forms in photosynthetic organisms

Humans have enormously increased the level of nitrogen (N) circulating in the troposphere and the earth surface during the last century, correlating with the population increase. As an undesirable consequence, high levels of reactive N are polluting the environment where humans inhabit. Nitric oxide (NO) is one of the reactive N species with both positive and negative impact on life. NO synthases (NOS) are enzymes that oxidize arginine to citrulline and generate the denitrifying intermediate NO which can be subsequently reduced to N2O and N2. NOS are large modular enzymes present in all kingdoms which through evolution were the result of multiple gene and genome duplication events together with changes in protein architecture (Andreakis et al. 2011). A recently described NOS from the marine unicellular microalgae Ostreococcus tauri, belonging to the picoplankton in oceans, adds new insights to study the evolution of the complex organization of these enzymes. In this opinion we discuss the structure diversity of the emerging new NOS forms described in prokaryotes and eukaryotes. Regarding the controversy about the existence of canonical NOS in higher plants, we propose that the latest findings support the existence of a high diversity of NOS forms in different lineages. Thereby, since higher plant species whose genomes have been fully sequenced, which are scarce, it cannot be discarded that a new form of NOS may have evolved in higher plants.Fil: Correa Aragunde, Maria Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: Foresi, Noelia Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: Lamattina, Lorenzo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata; Argentin

A singular nitric oxide synthase with a globin domain found in Synechococcus PCC 7335 mobilizes N from arginine to nitrate

The enzyme nitric oxide synthase (NOS) oxidizes L-arginine to NO and citrulline. In this work, we characterise the NOS from the cyanobacteria Synechococcus PCC 7335 (SyNOS). SyNOS possesses a canonical mammalian NOS architecture consisting of oxygenase and reductase domains. In addition, SyNOS possesses an unusual globin domain at the N-terminus. Recombinant SyNOS expressed in bacteria is active, and its activity is suppressed by the NOS inhibitor L-NAME. SyNOS allows E. coli to grow in minimum media containing L-arginine as the sole N source, and has a higher growth rate during N deficiency. SyNOS is expressed in Synechococcus PCC 7335 where NO generation is dependent on L-arginine concentration. The growth of Synechococcus is dramatically inhibited by L-NAME, suggesting that SyNOS is essential for this cyanobacterium. Addition of arginine in Synechococcus increases the phycoerythrin content, an N reservoir. The role of the novel globin domain in SyNOS is discussed as an evolutionary advantage, conferring new functional capabilities for N metabolism.Fil: Correa Aragunde, Maria Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: Foresi, Noelia Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: del Castello, Fiorella Paola. Universidad Nacional de Mar del Plata; ArgentinaFil: Lamattina, Lorenzo. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentin

Chimera of Globin/Nitric Oxide Synthase: Toward Improving Nitric Oxide Homeostasis and Nitrogen Recycling and Availability

As a result of anthropogenic activities, there are regions suffering extreme climate changes (hot temperatures, droughts, floods), that generate serious and harmful environmental and socio-economic consequences (Hoegh-Guldberg et al., 2018). Climate change has a strong impact on agriculture, mainly by increasing soil degradation and reducing land productivity (Olsson et al., 2019). Desertification decreases soil macronutrients as organic carbon (OC), phosphorus (P) and nitrogen (N) (Shang et al., 2013; Tang et al., 2015). Considerable reductions of OC, P and N are caused by a decline in soil water, vegetation and wind erosion. It is estimated that when soil water is less than 30%, OC and N decrease approximately 50% (Shang et al., 2013). The intensity and frequency of extreme climate events predicted will increase the competition for nutrients, notably N among plants and soil microorganisms (Bennett and Klironomos, 2019; Pugnaire et al., 2019).N availability is essential for net primary production and determines changes in total vegetation biomass and soil OC (Tharammal et al., 2019). Approximately 150 Tg/yr of N is spilled to the land surface as a result of industrial activities and fossil fuel combustion (Schlesinger, 2009). Huge amounts of N fertilizers are used to increase crop productivity, but only 25%?30% are retained in plant biomass (Nadelhoffer et al., 1999; Schlesinger, 2009). The excess of N is then transported to aquatic environments resulting in eutrophication and reduction of dissolved O2, percolated to the groundwater or loss to the atmosphere, increasing greenhouse gas (GHG) emissions such as nitrogen oxides (NOx) (Schlesinger, 2009; Breitburg et al., 2018). In this context, bio/technological solutions like genetic modification of crops are required to avoid, reduce and reverse GHG emissions and water eutrophication, contributing to climate change mitigation. New biotechnological strategies developed for the agriculture to increase N use efficiency (NUE) in crops would help to fulfill this purpose. In this opinion, we will discuss some studies of nitric oxide (NO) synthases (NOS) and nitrate reductase (NR) enzymes playing a collaborative role with globin (Hb) proteins, leading to NO and/or nitrate (NO3-) homeostasis in different organisms. We propose that chimeric globin-NOS such as the NOS from Synechococcus PCC 7335 (SyNOS) may have evolved in photosynthetic microorganisms contributing to a more efficient N recycling and sustaining growth in N fluctuating conditions. Engineered crops that maximize NUE would result in a better adaptation to changing climatic conditions with less N fertilization, preserving aquatic ecosystems and atmosphere.Fil: del Castello, Fiorella Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Nejamkin, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Foresi, Noelia Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Lamattina, Lorenzo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Correa Aragunde, Maria Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentin

Nitrogen Depletion Blocks Growth Stimulation Driven by the Expression of Nitric Oxide Synthase in Tobacco

Nitric oxide (NO) is a messenger molecule widespread studied in plant physiology. Latter evidence supports the lack of a NO-producing system involving a NO synthase (NOS) activity in higher plants. However, a NOS gene from the unicellular marine alga Ostreococcus tauri (OtNOS) was characterized in recent years. OtNOS is a genuine NOS, with similar spectroscopic fingerprints to mammalian NOSs and high NO producing capacity. We are interested in investigating whether OtNOS activity alters nitrogen metabolism and nitrogen availability, thus improving growth promotion conditions in tobacco. Tobacco plants were transformed with OtNOS under the constitutive CaMV 35S promoter. Transgenic tobacco plants expressing OtNOS accumulated higher NO levels compared to siblings transformed with the empty vector, and displayed accelerated growth in different media containing sufficient nitrogen availability. Under conditions of nitrogen scarcity, the growth promoting effect of the OtNOS expression is diluted in terms of total leaf area, protein content and seed production. It is proposed that OtNOS might possess a plant growth promoting effect through facilitating N remobilization and nitrate assimilation with potential to improve crop plants performance.Fil: Nejamkin, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Foresi, Noelia Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Mayta, Martín Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Lodeyro, Anabella Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: del Castello, Fiorella Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Correa Aragunde, Maria Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Carrillo, Nestor Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Lamattina, Lorenzo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentin

Nitric oxide is a ubiquitous signal for maintaining redox balance in plant cells: regulation of ascorbate peroxidase as a case study

Oxidative and nitrosative stresses and their respective antioxidant responses are common metabolic adjustments operating in all biological systems. These stresses result from an increase in reactive oxygen species (ROS) and reactive nitrogen species (RNS) and an imbalance in the antioxidant response. Plants respond to ROS and RNS accumulation by increasing the level of the antioxidant molecules glutathione and ascorbate and by activating specific antioxidant enzymes. Nitric oxide (NO) is a free radical considered to be toxic or protective depending on its concentration, combination with ROS compounds, and subcellular localization. In this review we focus on the mechanisms of NO action in combination with ROS on the regulation of the antioxidant system in plants. In particular, we describe the redox post-translational modifications of cytosolic ascorbate peroxidase and its influence on enzyme activity. The regulation of ascorbate peroxidase activity by NO as a redox sensor of acute oxidative stress or as part of a hormone-induced signalling pathway leading to lateral root development is presented and discussed.Fil: Correa Aragunde, Maria Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Foresi, Noelia Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Lamattina, Lorenzo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; Argentin

Auxin and Nitric Oxide: A Counterbalanced Partnership Ensures the Redox Cue Control Required for Determining Root Growth Pattern

Auxin is the main hormone that controls growth and developmental processes in plants. In the last decade, many studies confirmed the interplay between reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the auxin signaling transduction pathway. Nitric oxide (NO) is an RNS induced by, and required for the auxin-mediated lateral root formation and inhibition of the primary root elongation. Auxin induces both ROS and NO that, in turn, modulates reductases and peroxidases activities resulting in the attenuation of auxin signaling. As a consequence, a balance between ROS and NO concentrations appears to be essential for the control of the auxin action during root growth and developmental processes. In this review, we summarize and discuss the recent progress in the understanding of signaling and interacting components participating of the auxin-, NO- and ROS-modulated redox balance determining root growth pattern.Fil: Correa Aragunde, Maria Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Foresi, Noelia Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Lamattina, Lorenzo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentin

Auxin induces redox regulation of ascorbate peroxidase 1 activity by S-nitrosylation/denitrosylation balance resulting in changes of root growth pattern in Arabidopsis

S-nitrosylation of Cys-residues is one of the molecular mechanisms driven by nitric oxide (NO) for regulating biological functions of key proteins. While the studies on S-nitrosylation of Cys residues have served for identifying SNO-proteomes, the physiological relevance of protein S-nitrosylation/denitrosylation remains poorly understood. In this study, it is shown that auxin influences the balance of S-nitrosylated/denitrosylated proteins in roots of Arabidopsis seedlings. 2D-PAGE allowed the identification of ascorbate peroxidase 1 (APX1) as target of auxin-induced denitrosylation in roots. Auxin causes APX1 denitrosylation and partial inhibition of APX1 activity in Arabidopsis roots. In agreement, the S-nitrosylated form of recombinant APX1 expressed in E. coli is more active than the denitrosylated form. Consistently, Arabidopsis apx1 mutants have increased H2O2 accumulation in roots, shorter roots and less sensitivity to auxin than the wild type. It is postulated that an auxin-regulated counterbalance of APX1 S-nitrosylation/denitrosylation contributes to a fine-tuned control of root development and determination of root architecture.Fil: Correa Aragunde, Maria Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: Foresi, Noelia Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: Delledonne, Massimo. Universita Di Verona. Dipartimento Scientifico E Tecnologico; ItaliaFil: Lamattina, Lorenzo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata; Argentin

Analysis of the expression and activity of nitric oxide synthase from marine photosynthetic microorganisms

Nitric oxide (NO) functions as a signaling molecule in many biological processes in species belonging to all kingdoms of life. In animal cells, NO is synthesized primarily by NO synthase (NOS), an enzyme that catalyze the NADPH-dependent oxidation of l -arginine to NO and l -citrulline. Three NOS isoforms have been identifi ed, the constitutive neuronal NOS (nNOS) and endothelial NOS (eNOS) and one inducible (iNOS). Plant NO synthesis is complex and is a matter of ongoing investigation and debate. Despite evidence of an Arg-dependent pathway for NO synthesis in plants, no plant NOS homologs to animal forms have been identifi ed to date. In plants, there is also evidence for a nitrate-dependent mechanism of NO synthesis, catalyzed by cytosolic nitrate reductase. The existence of a NOS enzyme in the plant kingdom, from the tiny single-celled green alga Ostreococcus tauri was reported in 2010. O. tauri shares a common ancestor with higher plants and is considered to be part of an early diverging class within the green plant lineage. In this chapter we describe detailed protocols to study the expression and characterization of the enzymatic activity of NOS from O. tauri. The most used methods for the characterization of a canonical NOS are the analysis of spectral properties of the oxyferrous complex in the heme domain, the oxyhemoglobin (oxyHb) and citrulline assays and the NADPH oxidation for in vitro analysis of its activity or the use of fl uorescent probes and Griess assay for in vivo NO determination. We further discuss the advantages and drawbacks of each method. Finally, we remark factors associated to the measurement of NOS activity in photosynthetic organisms that can generate misunderstandings in the interpretation of results.Fil: Foresi, Noelia Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Correa Aragunde, Maria Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Santolini, Jerome. Centre National de la Recherche Scientifique; Francia. iBiTec-S; FranciaFil: Lamattina, Lorenzo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentin

Expression of nitric oxide synthases from photosynthetic microorganisms improves growth and stress tolerance in E. coli

Nitric oxide synthase (NOS) catalyzes the oxidation of the substrate L-Arginine (Arg) to produce citrulline and nitric oxide (NO). We have characterized NOS from two photosynthetic microorganisms: the NOS from the alga Ostreococcus tauri (OtNOS) and the cyanobacteria Synechococcus PCC 7335 (SyNOS). OtNOS and SyNOS possess distinct biochemical properties. OtNOS is a canonical NOS similar to animal NOS with an ultrafast NO producing activity. On the contrary, an extra globin domain present in SyNOS enzyme oxidizes over 70 % of the NO-produced to nitrate (NO3-). Here we describethe expression of recombinant OtNOS and SyNOS in Escherichia coli BL12 strain and analyze bacterial growth and tolerance to nitrosative stress. Results show that the E. coli cultures expressing OtNOS and SyNOS reach a higher OD at the exponential phase with respect to bacteria transformed with the empty vector (EV). This result correlates with higher NOS protein levels assayed by immunoblot, total protein and nitrate content in NOS recombinant strain cultures. Moreover, the expression of SyNOS and at less extent of OtNOS confers the ability to grow in minimal medium with Arg as a sole N source (and plenty C-source), suggesting that NOS enzymes are active in E. coli. The high NO producing activity reported in OtNOS correlates with the flavohemoglobin hmp induction in E. coli strain expressing OtNOS, suggesting that this strain senses nitrosative stress. Furthermore, nitrosative stress generated by the addition of 1 mM of the NO donor sodium nitroprusside (SNP) reduced growth rate (0.4-fold respect to no SNP addition) in bacterial culture expressing EV. However, the expression of recombinant OtNOS and at less extent SyNOS, attenuated SNP toxicity (0.8- and 0.6-fold, respectively, compared to no SNP addition). E. coli does not synthesize the major NOS cofactor tetrahydrobiopterin (BH4). Bioinformatics tools and ligand docking analysis were used to provide evidence supporting tetrahydromonapterin (MH4) as a possible pterin cofactor required for NOS catalytic activity in E. coli. These results open an exciting new window about the versatility of pterin cofactor working in the different NOSs dispersed in distant organisms along the life tree. In summary, our results show that NOS from photosynthetic microorganisms increases the growth and confers nitrosative stress tolerance in E. coli. Supported by AGENCIA, CONICET and UNMdPFil: Correa Aragunde, Maria Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Nejamkin, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: del Castello, Fiorella Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Foresi, Noelia Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Lamattina, Lorenzo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaReunión Conjunta SAIB-SAMIGE 2020. LVI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular. LVI Reunión Anual Sociedad Argentina de Bioquímica y Biología Molecular (SAIB). XV Reunión Anual Sociedad Argentina de Microbiología General (SAMIGE)Buenos AiresArgentinaSociedad Argentina de Investigación en Bioquímica y Biología MolecularAsociación Civil de Microbiología Genera

Nitric oxide synthases from photosynthetic organisms improve growth and confer nitrosative stress tolerance in E. coli. Insights on the pterin cofactor

Nitric oxide synthase (NOS) synthesizes NO from the substrate L-arginine (Arg). NOS with distinct biochemical properties were characterized from two photosynthetic microorganisms, the unicellular algae Ostreococcus tauri (OtNOS) and the cyanobacteria Synechococcus PCC 7335 (SyNOS). In this work we studied OtNOS and SyNOS recombinantly expressed in E. coli and analyzed bacterial growth and tolerance to nitrosative stress. Results show that the expression of OtNOS and SyNOS promotes bacterial growth and allows metabolizing Arg as N source. In accordance to a high NO producing activity, OtNOS expression induces the hmp flavohemoglobin in E. coli, suggesting that this strain is sensing nitrosative stress. The addition of 1 mM of the NO donor sodium nitroprusside (SNP) is toxic and generates a strong nitrosative stress. The expression of OtNOS or SyNOS reduced SNP toxicity restoring bacterial growth. Finally, using bioinformatic tools and ligand docking analyses, we propose tetrahydromonapterin (MH4), an endogenous pterin found in E. coli, as potential cofactor required for NOS catalytic activity. Our findings could be useful for the development of biotechnological applications using NOS expression to improve growth in bacteria.Fil: Correa Aragunde, Maria Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Nejamkin, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: del Castello, Fiorella Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Foresi, Noelia Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Lamattina, Lorenzo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentin