A Luciferase-Like Monooxygenase and Flavin Reductase Pair AbmE2/AbmZ Catalyzes Baeyer–Villiger Oxidation in Neoabyssomicin Biosynthesis

ACS Catalysis ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 2591-2595 ◽  
Author(s):  
Xiaoqi Ji ◽  
Jiajia Tu ◽  
Yongxiang Song ◽  
Chunyan Zhang ◽  
Liyan Wang ◽  
...  
Keyword(s):  
Flavin Reductase ◽  
Villiger Oxidation

scholarly journals Flavin Adenine Dinucleotide-Dependent Halogenase XanH and Engineering of Multifunctional Fusion Halogenases

2020 ◽  
Vol 86 (18) ◽  
Author(s):  
Lingxin Kong ◽  
Qing Wang ◽  
Zixin Deng ◽  
Delin You
Keyword(s):  
Protein Engineering ◽  
Fusion Protein ◽  
Natural Product ◽  
Flavin Adenine Dinucleotide ◽  
High Efficiency ◽  
Genetic Manipulation ◽  
Good Alternative ◽  
Limited Information ◽  
Flavin Reductase ◽  
Free Standing

ABSTRACT Xantholipin (compound 1), a polycyclic xanthone antibiotic, exhibited strong antibacterial activities and showed potent cytotoxicity. The biosynthetic gene cluster of compound 1 has been identified in our previous work, and the construction of xanthone nucleus has been well demonstrated. However, limited information of the halogenation involved in compound 1 biosynthesis is available. In this study, based on the genetic manipulation and biochemical assay, we characterized XanH as an indispensable flavin adenine dinucleotide (FAD)-dependent halogenase (FDH) for the biosynthesis of compound 1. XanH was found to be a bifunctional protein capable of flavin reduction and chlorination and exclusively used the NADH. However, the reduced flavin could not be fully and effectively utilized, and the presence of an extra flavin reductase (FDR) and chemical-reducing agent could promote the halogenation. XanH accepted its natural free-standing substrate with angular fused polycyclic aromatic systems. Meanwhile, it exhibited moderate halogenation activity and possessed high substrate specificity. The requirement of extra FDR for higher halogenation activity is tedious for future engineering. To facilitate efforts in engineering XanH derivative proteins, we constructed the self-sufficient FDR-XanH fusion proteins. The fusion protein E1 with comparable activities to that of XanH could be used as a good alternative for future protein engineering. Taken together, these findings reported here not only improve the understanding of polycyclic xanthones biosynthesis but also expand the substrate scope of FDH and pave the way for future engineering of biocatalysts for new active substance synthesis. IMPORTANCE Halogenation is important in medicinal chemistry and plays an essential role in the biosynthesis of active secondary metabolites. Halogenases have evolved to catalyze reactions with high efficiency and selectivity, and engineering efforts have been made to engage the selective reactivity in natural product biosynthesis. The enzymatic halogenations are an environmentally friendly approach with high regio- and stereoselectivity, which make it a potential complement to organic synthesis. FDHs constitute one of the most extensively elucidated class of halogenases; however, the inventory awaits to be expanded for biotechnology applications and for the generation of halogenated natural product analogues. In this study, XanH was found to reduce flavin and halogenated the freely diffusing natural substrate with an angular fused hexacyclic scaffold, findings which were different from those for the exclusively studied FDHs. Moreover, the FDR-XanH fusion protein E1 with comparable reactivity to that of XanH serves as a successful example of genetic fusions and sets an important stage for future protein engineering.

scholarly journals Gene Cloning and Molecular Characterization of a Two-Enzyme System Catalyzing the Oxidative Detoxification of β-Endosulfan

2002 ◽  
Vol 68 (12) ◽  
pp. 6237-6245 ◽  
Author(s):  
Tara D. Sutherland ◽  
Irene Horne ◽  
Robyn J. Russell ◽  
John G. Oakeshott
Keyword(s):  
Shuttle Vector ◽  
Open Reading Frame ◽  
Cosmid Library ◽  
Flavin Mononucleotide ◽  
Flavin Reductase ◽  
Reading Frame ◽  
Reductase Gene ◽  
Degradation Activity ◽  
Layer Chromatography

ABSTRACT The gram-positive bacterium Mycobacterium sp. strain ESD is able to use the cyclodiene insecticide endosulfan as a source of sulfur for growth. This activity is dependent on the absence of sulfite or sulfate in the growth medium. A cosmid library of strain ESD DNA was constructed in a Mycobacterium-Escherichia coli shuttle vector and screened for endosulfan-degrading activity in Mycobacterium smegmatis, a species that does not degrade endosulfan. Using this method, we identified a single cosmid that conferred sulfur-dependent endosulfan-degrading activity on the host strain. An open reading frame (esd) was identified within this cosmid that, when expressed behind a constitutive promoter in a mycobacterial expression vector, conferred sulfite- and sulfate-independent β-endosulfan degradation activity on the recombinant strain. The translation product of this gene (Esd) had up to 50% sequence identity with an unusual family of monooxygenase enzymes that use reduced flavins, provided by a separate flavin reductase enzyme, as cosubstrates. An additional partial open reading frame was located upstream of the Esd gene that had sequence homology to the same monooxygenase family. A flavin reductase gene, identified in the M. smegmatis genome, was cloned, expressed, and used to provide reduced flavin mononucleotide for Esd in enzyme assays. Thin-layer chromatography and gas chromatography analyses of the enzyme assay mixtures revealed the disappearance of β-endosulfan and the appearance of the endosulfan metabolites, endosulfan monoaldehyde and endosulfan hydroxyether. This suggests that Esd catalyzes the oxygenation of β-endosulfan to endosulfan monoaldehyde and endosulfan hydroxyether. Esd did not degrade either α-endosulfan or the metabolite of endosulfan, endosulfan sulfate.

scholarly journals Cloning, Expression, Characterization, and Biocatalytic Investigation of the 4-Hydroxyacetophenone Monooxygenase from Pseudomonas putida JD1

2009 ◽  
Vol 75 (10) ◽  
pp. 3106-3114 ◽  
Author(s):  
Jessica Rehdorf ◽  
Christian L. Zimmer ◽  
Uwe T. Bornscheuer
Keyword(s):  
Pseudomonas Putida ◽  
Open Reading Frames ◽  
Gene Encoding ◽  
Open Chain ◽  
Aromatic Ketones ◽  
Heteroaromatic Compounds ◽  
Aliphatic Ketones ◽  
Expression Characterization ◽  
Reading Frames ◽  
Villiger Oxidation

ABSTRACT While the number of available recombinant Baeyer-Villiger monooxygenases (BVMOs) has grown significantly over the last few years, there is still the demand for other BVMOs to expand the biocatalytic diversity. Most BVMOs that have been described are dedicated to convert efficiently cyclohexanone and related cyclic aliphatic ketones. To cover a broader range of substrate types and enantio- and/or regioselectivities, new BVMOs have to be discovered. The gene encoding a BVMO identified in Pseudomonas putida JD1 converting aromatic ketones (HAPMO; 4-hydroxyacetophenone monooxygenase) was amplified from genomic DNA using SiteFinding-PCR, cloned, and functionally expressed in Escherichia coli. Furthermore, four other open reading frames could be identified clustered around this HAPMO. It has been suggested that these proteins, including the HAPMO, might be involved in the degradation of 4-hydroxyacetophenone. Substrate specificity studies revealed that a large variety of other arylaliphatic ketones are also converted via Baeyer-Villiger oxidation into the corresponding esters, with preferences for para-substitutions at the aromatic ring. In addition, oxidation of aldehydes and some heteroaromatic compounds was observed. Cycloketones and open-chain ketones were not or poorly accepted, respectively. It was also found that this enzyme oxidizes aromatic ketones such as 3-phenyl-2-butanone with excellent enantioselectivity (E ≫100).

Chemo-enzymatic Baeyer–Villiger oxidation of cyclopentanone and substituted cyclopentanones

2008 ◽  
Vol 54 (3-4) ◽  
pp. 61-66 ◽  
Author(s):  
María Yolanda Rios ◽  
Enrique Salazar ◽  
Horacio F. Olivo
Keyword(s):  
Villiger Oxidation
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