A role of nitrite reductase (NirBD) for NO homeostatic regulation inStreptomyces coelicolorA3(2)

Abstract

Although nitric oxide (NO) is an important signaling molecule in bacteria and higher organisms, excessive intracellular NO is highly reactive and dangerous. Therefore, living cells need strict regulation systems for cellular NO homeostasis. Recently, we discovered that Streptomyces coelicolor A3(2) retains the nitrogen oxide cycle (NO→NO→NO→NO) and nitrite removal system. The nitrogen oxide cycle regulates cellular NO levels, thereby controlling secondary metabolism initiation (red-pigmented antibiotic, RED production) and morphological differentiation. Nitrite induces gene expression in neighboring cells, suggesting another role for this cycle as a producer of transmittable intercellular communication molecules. Here, we demonstrated that ammonium-producing nitrite reductase (NirBD) is involved in regulating NO homeostasis in S. coelicolor A3(2). NirBD was constitutively produced in culture independently of GlnR, a known transcriptional factor. NirBD cleared the accumulated nitrite from the medium. Nir deletion mutants showed increased NO-dependent gene expression at later culture stages, whereas the wild-type M145 showed decreased expression, suggesting that high NO concentration was maintained in the mutant. Moreover, the nir deletion mutant produced more RED than that produced by the wild-type M145. These results suggest that NO removal by NirBD is important to regulate NO homeostasis and to complete NO signaling in S. coelicolor.

Systems metabolic engineering of Streptomyces venezuelae for the enhanced production of pikromycin

“…Also, FMNRx2 and SULRi (Zeghouf et al, 2000) consume NADPH, and therefore, downregulating these two reactions would save NADPH for the biosynthesis of pikromycin. For SULRi, its corresponding gene, AQF52_RS30320, is known to also encode nitrite reductase (reaction ID: “NOR_syn”); deletion of this gene was reported to increase the production of a secondary metabolite, undecylprodigiosin, in S. coelicolor (Yukioka et al, 2017). Finally, precorrin‐2 is a key precursor of cobalamin (vitamin B 12 ) and siroheme, both involved in various metabolic processes as cofactors (Fang et al, 2016).…”

“…coelicolor (Yukioka et al, 2017). Finally, precorrin-2 is a key precursor of cobalamin (vitamin B 12 ) and siroheme, both involved in various metabolic processes as cofactors (Fang et al, 2016).…”

Genome analysis of Pseudomonas sp. OF001 and Rubrivivax sp. A210 suggests multicopper oxidases catalyze manganese oxidation required for cylindrospermopsin transformation

“…Furthermore, strain OF001 encodes genes related with assimilatory nitrate reduction, including nitrate transport, the ammonium-forming nitrite reductase small subunit nasD , and the nitrate reductase nasA [ 70 – 73 ]. Strain OF001 also possesses two nitrite reductases, one in a predicted operon together with the nitrate reductase nasA , and the other as an independent regulated gene (Additional file 1 : Table S4).…”

“…Moreover, strain A210 encodes genes related with assimilatory nitrate reduction, including nitrate transport, the ammonium-forming nitrite reductase small subunit nirB , and the nitrate reductase nasA [ 70 – 73 ].…”

Inter-Kingdom beach warfare: Microbial chemical communication activates natural chemical defences

“…7D) with nitrate/nitrite reductases (NaR and NiR) [37] could result in NO production and that aminoguandine (AG) inhibits XOR in vitro at concentrations above 5 mM [38]. In fact, NaR and NiR have been shown to be involved in NO production in Streptomyces coelicolor, a model organism lacking a NOS [39]. Further mining of the CMB-StM0423 genome identified XOR, NiR/NaR homologs (Supplementary Information Section 18, PEGS 6836 and 5129-5130/5125, respectively).…”