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

• Published in: Nitric oxide Vol. 119; pp. 41 - 49
• Main Authors: Correa-Aragunde, Natalia, Nejamkin, Andrés, Del Castello, Fiorella, Foresi, Noelia, Lamattina, Lorenzo
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2022
• Subjects: Algal Proteins - chemistry; Algal Proteins - metabolism; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Biopterins - analogs & derivatives; Biopterins - chemistry; Biopterins - metabolism; Chlorophyta - enzymology; Coenzymes - chemistry; Coenzymes - metabolism; Escherichia coli; Escherichia coli - growth & development; Escherichia coli - metabolism; Molecular Docking Simulation; Nitric Oxide - metabolism; Nitric oxide synthase; Nitric Oxide Synthase - chemistry; Nitric Oxide Synthase - metabolism; Nitrosative Stress - physiology; NOS pterin Cofactor; Ostreococcus tauri; Protein Binding; Reactive Oxygen Species - metabolism; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Synechococcus - enzymology; Synechococcus PCC 7335; Tetrahydromonapterin (MH4); Ostreococcus tauri; Nitric oxide synthase; Tetrahydromonapterin (MH4); Synechococcus PCC 7335; Escherichia coli; NOS pterin Cofactor
• ISSN: 1089-8603; 1089-8611
• DOI: 10.1016/j.niox.2021.12.005

Nitric oxide synthase (NOS) catalyzes NO formation from the substrate l-arginine (Arg). Previously, 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 the effect of recombinant OtNOS and SyNOS expressed under IPTG-induced promoter in E. coli, a bacterium that lacks NOS. Results show that OtNOS and SyNOS expression promote E. coli growth in a nutrient replete medium and allow to better metabolize Arg as N source. In LB medium, OtNOS induces the expression of the NO dioxygenase hmp in E. coli, in accordance with high NO levels visualized with the probe DAF-FM DA. In contrast, SyNOS expression does not induce hmp and show a slight increase of NO production compared to OtNOS. NOS expression reduces ROS production and increases viability of E. coli cultures growing in LB. A strong nitrosative stress provoked by the addition of 1 mM of the NO donors sodium nitroprusside (SNP) and nitrosoglutathione (GSNO) inhibits bacterial growth rate. Under these conditions, the expression of OtNOS or SyNOS counteracts NO donor toxicity restoring bacterial growth. Finally, using bioinformatic tools and ligand docking analyses, we postulate that tetrahydromonapterin (MH4), an endogenous pterin found in E. coli, could act as cofactor required for NOS catalytic activity. Our findings could be useful for the development of biotechnological applications using NOS expression to improve growth in NOS-lacking bacteria. •The NO synthase (NOS) from photosynthetic microorganisms were expressed in E. coli.•Expression of NOS increases bacterial growth and tolerance to nitrosative stress.•NOS expression contribute to bacterial growth using Arg as sole N source in the presence of IPTG.•In silico analyses suggest that MH4 could be used as redox NOS cofactor in E. coli.