Heterocyclic Aromatic N-Oxidation in the Biosynthesis of Phenazine Antibiotics from Lysobacter antibioticus

Abstract

Heterocyclic aromatic N-oxides often have potent biological activities, but the mechanism for aromatic N-oxidation is unclear. Six phenazine antibiotics were isolated from Lysobacter antibioticus OH13. A 10 gene cluster was identified for phenazine biosynthesis. Mutation of LaPhzNO1 abolished all N-oxides, while non-oxides markedly increased. LaPhzNO1 is homologous to Baeyer-Villiger flavoproteins but was shown to catazlye phenazine N-oxidation. LaPhzNO1 and LaPhzS together converted phenazine 1,6-dicarboxylic acid to 1,6-dihydroxyphenazine N5,N10-dioxide. LaPhzNO1 also catalyzed N-oxidation of 8-hydroxyquinoline.

Characterization of the flavoenzyme XiaK as an N-hydroxylase and implications in indolosesquiterpene diversification

“…Flavoenzymes play important roles in N-oxidations of natural products to introduce N -hydroxyl, 40 – 44 , 46 , 48 , 49 oxime, 50 – 54 nitro, 45 , 47 , 55 – 60 nitrone, 61 , 62 and nitrile functional groups. 63 , 64 In this study, XiaK was biochemically characterized as a FAD-dependent N -hydroxylase that catalyzes the conversion of XMA ( 1 ) into NOXM ( 12 ).…”

Global landscape of phenazine biosynthesis and biodegradation reveals species-specific colonization patterns in agricultural soils and crop microbiomes

“…In contrast, the phenazine repertoire of L. antibioticus , as well as the specific genes responsible for their synthesis and modification, were recently characterized in depth. Specifically, the L. antibioticus gene products La PhzS and La PhzNO1 were shown to catalyze the decarboxylative hydroxylation and N-oxidations of PDC to generate the phenazine iodinin ( Zhao et al, 2016 ). In addition, the SAM-dependent O-methyltransferase, La PhzM, was later found to convert iodinin into the highly toxic phenazine, myxin ( Jiang et al, 2018 ).…”

“…UV-Vis and positive MS scans were acquired for each run. The known masses for phenazine previously detected in L. antibioticus ( Jiang et al, 2018 ; Zhao et al, 2016 ) were identified by comparing among WT, Δ phzT and Δ phzA cultures. Phenazine UV-absorbance was measured at 254 nm, 280 nm and 288 nm ( Figure 4—figure supplement 2 ).…”

A Biocatalytic Synthesis of HeteroaromaticN‐Oxides by Whole Cells ofEscherichia coliExpressing the Multicomponent, Soluble Di‐Iron Monooxygenase (SDIMO) PmlABCDEF

“…Among the isolated enzymes, methane monooxygenase and cytochrome P450 as well as Rhodococcus jostii TMP1 cells have been shown to oxidize N ‐heterocycles with a presumed formation of N ‐oxides; however, further studies have not been elaborated. Other efforts to exploit enzymes or cells for the synthesis of N ‐oxides involved peroxygenase from Agrocybe aegerita , cyclohexanone monooxygenase from Lysobacter antibioticus , and whole cells of Verticillium sp . GF39 and Burkholderia sp .…”