scholarly journals Aromatic Halogenation by Using Bifunctional Flavin Reductase-Halogenase Fusion Enzymes

ChemBioChem ◽  
2017 ◽  
Vol 18 (21) ◽  
pp. 2099-2103 ◽  
Author(s):  
Mary C. Andorfer ◽  
Ketaki D. Belsare ◽  
Anna M. Girlich ◽  
Jared C. Lewis
Keyword(s):  
Flavin Reductase ◽  
Fusion Enzymes

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 Amperometric Biosensors Based on Direct Electron Transfer Enzymes

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4525
Author(s):  
Franziska Schachinger ◽  
Hucheng Chang ◽  
Stefan Scheiblbrandner ◽  
Roland Ludwig
Keyword(s):  
Electron Transfer ◽  
Electrode Materials ◽  
Direct Electron Transfer ◽  
Accurate Determination ◽  
Direct Electrochemistry ◽  
Product Analysis ◽  
Amperometric Biosensors ◽  
Chemical Surface ◽  
Fusion Enzymes ◽  
Cost Efficient

The accurate determination of analyte concentrations with selective, fast, and robust methods is the key for process control, product analysis, environmental compliance, and medical applications. Enzyme-based biosensors meet these requirements to a high degree and can be operated with simple, cost efficient, and easy to use devices. This review focuses on enzymes capable of direct electron transfer (DET) to electrodes and also the electrode materials which can enable or enhance the DET type bioelectrocatalysis. It presents amperometric biosensors for the quantification of important medical, technical, and environmental analytes and it carves out the requirements for enzymes and electrode materials in DET-based third generation biosensors. This review critically surveys enzymes and biosensors for which DET has been reported. Single- or multi-cofactor enzymes featuring copper centers, hemes, FAD, FMN, or PQQ as prosthetic groups as well as fusion enzymes are presented. Nanomaterials, nanostructured electrodes, chemical surface modifications, and protein immobilization strategies are reviewed for their ability to support direct electrochemistry of enzymes. The combination of both biosensor elements—enzymes and electrodes—is evaluated by comparison of substrate specificity, current density, sensitivity, and the range of detection.

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.

A bacterial flavin reductase system reduces chromate to a soluble chromium(III)–NAD+ complex

2002 ◽  
Vol 294 (1) ◽  
pp. 76-81 ◽  
Author(s):  
Geoffrey J. Puzon ◽  
James N. Petersen ◽  
Arthur G. Roberts ◽  
David M. Kramer ◽  
Luying Xun
Keyword(s):  
Flavin Reductase

scholarly journals Identification of the NADH-oxidase gene in Trichomonas vaginalis

2019 ◽  
Vol 119 (2) ◽  
pp. 683-686 ◽  
Author(s):  
Aline Lamien-Meda ◽  
David Leitsch
Keyword(s):  
Oxidase Activity ◽  
Trichomonas Vaginalis ◽  
Nadh Oxidase ◽  
Flavin Mononucleotide ◽  
Flavin Reductase ◽  
Oxidase Gene ◽  
Reading Frame ◽  
Sexually Transmitted ◽  
Cell Extracts ◽  
Nadh Oxidase Activity

AbstractThe microaerophilic human parasite Trichomonas vaginalis causes infections in the urogenital tract and is one of the most often sexually transmitted pathogens worldwide. Due to its anaerobic metabolism, it has to quickly remove intracellular oxygen in order to avoid deactivation of essential metabolic enzymes such as oxygen-sensitive pyruvate:ferredoxin oxidoreductase (PFOR). Two major enzyme activities which are responsible for the removal, i.e. reduction, of molecular oxygen have been identified in T. vaginalis flavin reductase, formerly designated NADPH oxidase, which indirectly reduces oxygen to hydrogen peroxide via flavin mononucleotide (FMN), and NADH oxidase which reduces oxygen to water. Flavin reductase has been identified and characterized at the gene level as well as enzymatically, but NADH oxidase has so far only been characterized enzymatically with enzyme isolated from T. vaginalis cell extracts. In this study, we identified NADH oxidase by mass spectrometry after isolation of the enzyme from gel bands positively staining for NADH oxidase activity. In strain C1 (ATCC 30001) which is known to lack NADH oxidase activity completely, the NADH oxidase gene has a deletion at position 1540 of the open reading frame leading to a frame shift and, as a consequence, to premature termination of the encoded polypeptide.

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