Monooxygenase LaPhzX is Involved in Self-Resistance Mechanisms during the Biosynthesis of N-Oxide Phenazine Myxin

Abstract

Self-resistance genes are deployed by many microbial producers of bioactive natural products to avoid self-toxicity. Myxin, a di-N-oxide phenazine produced by Lysobacter antibioticus OH13, is toxic to many microorganisms and tumor cells. Here, we uncovered a self-defense strategy featuring the antibiotic biosynthesis monooxygenase (ABM) family protein LaPhzX for myxin degradation. The gene LaPhzX is located in the myxin biosynthetic gene cluster (LaPhz), and its deletion resulted in bacterial mutants that are more sensitive to myxin. In addition, the LaPhzX mutants showed increased myxin accumulation and reduction of its derivative, compound 4, compared to the wild-type strain. Meanwhile, in vitro biochemical assays demonstrated that LaPhzX significantly degraded myxin in the presence of nicotinamide adenine dinucleotide phosphate (NADPH), nicotinamide adenine dinucleotide (NADH), flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD). In addition, heterologous expression of LaPhzX in Xanthomonas oryzae pv. oryzae and Escherichia coli increased their resistance to myxin. Overall, our work illustrates a monooxygenase-mediated self-resistance mechanism for phenazine antibiotic biosynthesis.

Metabolic Engineering of Pseudomonas chlororaphis for De Novo Production of Iodinin from Glycerol

“…Furthermore, although the phzNO1 Na overexpression strategy was performed, it had little effect on improving iodinin production. This may be indicated by the lack of self-resistance, efflux pump, or the low solubility of iodinin, , which greatly affected its production in P. chlororaphis.…”

“…Furthermore, although the phzNO1 Na overexpression strategy was performed, it had little effect on improving iodinin production. This may be indicated by the lack of self-resistance, efflux pump, or the low solubility of iodinin, 49,50 which greatly affected its production in P. chlororaphis. Additionally, we suggested that strain adaptation evolution, enhanced precursor supply, fermentation strategy optimization, and protein engineering of phzNO1 La are all useful strategies to further improve the production of iodinin in P. chlororaphis.…”

Quinoxaline 1,4-Dioxides: Advances in Chemistry and Chemotherapeutic Drug Development

“…As mentioned earlier, aliphatic and aromatic N -oxides are known as prodrugs due to their ability to be reduced by various oxidoreductases expressed in bacterial and tumor cells. Moreover, the attention given to heterocyclic N -oxides, particularly quinoxaline derivatives, can be explained by the presence of this scaffold in natural bioactive compounds, such as iodinin, its analog myxin, echinomycin, and aspergilic acid [ 121 , 122 ].…”

The versatility of non-heme diiron monooxygenase PmlABCDEF: a single biocatalyst for a plethora of oxygenation reactions

“…In this section, the attention is focused on the enzymatic synthesis of N-heteroaromatic N-oxides. The use of biological systems to obtain aromatic N-oxides is quite rarely reported, 15,[23][24][25][26] while the cases of non-heme diiron enzymes are even more limited. 27 Remarkably, monocyclic nitrogen compounds were among the best substrates of all tested compounds for PmlABCDEF monooxygenase (Pml).…”