Dye-decolorizing Peroxidase Research Articles

Draft Genome Sequence of Pseudonocardia autotrophica Strain DSM 43083, an Efficient Producer of Peroxidases for Lignin Modification

ABSTRACTPseudonocardia autotrophica strain DSM 43083 is a filamentous actinobacterium and was described to degrade or modify lignin. Here, we present its draft genome sequence, with a size of 5.8 Mb, to unravel the gene set coding for promising monooxygenases, dioxygenases, and DyP-type peroxidases associated with aromatic metabolism and lignin modification.

Crystal structure and biochemical features of dye-decolorizing peroxidase YfeX from Escherichia coli O157 Asp143 and Arg232 play divergent roles toward different substrates

YfeX from Escherichia coli O157 is a bacterial dye-decolorizing peroxidase that represents both dye-decoloring activity and typical peroxidase activity. We reported the crystal structure of YfeX bound to heme at 2.09 Å resolution. The YfeX monomer resembles a ferredoxin-like fold and contains two domains. The three conserved residues surrounding the heme group are His215, Asp143 and Arg232. His215 functions as the proximal axial ligand of the heme iron atom. Biochemical data show that the catalytic significance of the conserved Asp143 and Arg232 depends on the substrate types and that YfeX may adopt various catalytic mechanisms toward divergent substrates. In addition, it is observed that an access tunnel spans from the protein molecular surface to the heme distal region, it serves as the passageway for the entrance and binding of the H2O2.

Characterization of a novel DyP-type peroxidase from Streptomyces avermitilis

DyP-type peroxidases are a heme peroxidase family with unique properties whose members are widely distributed from prokaryotes to eukaryotes. DyP-type peroxidases are subdivided into class P, I and V based on structure-based sequence alignment. Class V enzymes possess degradation activities for anthraquinone dyes, and include extra sequences compared with class P and I. Class V enzymes are mainly found in fungi, with only two such proteins, AnaPX and DyP2, reported in bacteria. Here, we heterologously expressed, purified and biochemically characterized SaDyP2 protein, predicted to belong to class V. SaDyP2 was purified as a ∼50kDa enzyme containing a heme cofactor and was found to oxidize the typical peroxidase substrates, ABTS and DMP. SaDyP2 was generally thermostable and exhibited a lower optimal pH, a feature typical of DyP-type peroxidases. It also degraded anthraquinone dyes, a specific substrate of DyP-type peroxidases, although the kcat for SaDyP2 was lower than that for other class V enzymes. The Km value of SaDyP2 for anthraquinone dye was similar to that of other enzymes of this class. Homology modeling revealed that the structure of SaDyP2 best fit that of class V enzymes.

Rational design of artificial dye-decolorizing peroxidases using myoglobin by engineering Tyr/Trp in the heme center.

The rational design of metalloenzymes provides advantages not only for illustrating the structure and function relationship of native enzymes, but also for creating functional artificial enzymes comparable to native enzymes. Dye-decolorizing peroxidases (DyPs) are a new family of heme peroxidases and have received much attention recently. Inspired by the structural features of native DyPs with multiple Tyr and Trp residues, we herein aimed to design functional artificial DyPs using myoglobin (Mb), an O2 carrier as a protein scaffold, by further introduction of Tyr/Trp into the secondary sphere of the heme center in the F43Y Mb mutant. The latter has been shown to possess a novel Tyr-heme cross-link and exhibit enhanced peroxidase activity, which provides an ideal platform to design a series of derivatives, including F43Y/F46Y Mb, F43Y/I107Y Mb, F43Y/F138 W Mb and F43Y/I107Y/F138 W Mb. Our design revealed that the Tyr-heme cross-link was well-retained in the mutants except for F43Y/F46Y Mb, as confirmed by X-ray crystal structure analysis. More importantly, stopped-flow kinetic studies showed that these derivatives exhibit enhanced dye-decolorizing peroxidase activities compared to that of wild-type (WT) Mb. This is particularly the case for the double mutant F43Y/F138 W Mb, exhibiting an overall catalytic efficiency (kcat/Km) of 110 670 M-1 s-1, which is ∼144-fold and ∼20-fold that of WT Mb and F43Y Mb, respectively, and is ∼4.3-fold that of native DyP from Vibrio cholerae. Stopped-flow, electron paramagnetic resonance (EPR) and isothermal titration calorimetry (ITC) studies further provided insights into the activation of H2O2 and the binding of a substrate, reactive blue 19 (RB19), to the double mutant. This study provides valuable information for elucidating the structure and dye-decolorizing function relationship of peroxidases, and also clues for the design of other functional artificial heme enzymes.

Enzymatic mechanisms and detoxification of dry olive-mill residue by Cyclocybe aegerita, Mycetinis alliaceus and Chondrostereum purpureum

The detoxification of dry olive-mill residue (DOR), a lignocellulosic by-product, was investigated using three agaric fungi: Cyclocybe aegerita, Mycetinis alliaceus and Chondrostereum purpureum. The lignin-modifying enzymes (LME) secretion pattern of the above-mentioned fungi such as DyP-type peroxidase (DyP), laccase (Lac), unspecific peroxygenase (UPO), and manganese peroxidase (MnP) was determined in presence and absence of DOR. In C. aegerita, a laccase (Lac) and unspecific peroxygenase (UPO) induction was found when DOR was present in the medium. Thus, these enzymes appeared to be responsible for DOR detoxification and, indirectly, its plant-growth-promoting effect. In the experiment performed with M. alliaceus, no differences were found in DyP-type peroxidase (DyP) secretion when the basal barley medium was supplemented with DOR. However, MnP and Lac activities in DOR-barley reached a maximum after 5 weeks of incubation with a concomitant decline in DOR phytotoxicity. C. purpureum completely eliminated DOR phytotoxicity but no significant production of LME was detected in soy or barley fungal media. Other enzymatic mechanisms were also investigated, in relation to hydrolytic enzymes and the intracellular system cytochrome P450 monooxygenase (CYPs). Our results suggest the participation of a complex enzymatic system (intra and extracellular) in C. purpureum for the biotransformation of DOR.

Identification of Surface-Exposed Protein Radicals and A Substrate Oxidation Site in A-Class Dye-Decolorizing Peroxidase from Thermomonospora curvata.

Dye-decolorizing peroxidases (DyPs) are a family of heme peroxidases, in which a catalytic distal aspartate is involved in H2O2 activation to catalyze oxidations in acidic conditions. They have received much attention due to their potential applications in lignin compound degradation and biofuel production from biomass. However, the mode of oxidation in bacterial DyPs remains unknown. We have recently reported that the bacterial TcDyP from Thermomonospora curvata is among the most active DyPs and shows activity toward phenolic lignin model compounds (J. Biol. Chem.2015, 290, 23447). Based on the X-ray crystal structure solved at 1.75 Å, sigmoidal steady-state kinetics with Reactive Blue 19 (RB19), and formation of compound II-like product in the absence of reducing substrates observed with stopped-flow spectroscopy and electron paramagnetic resonance (EPR), we hypothesized that the TcDyP catalyzes oxidation of large-size substrates via multiple surface-exposed protein radicals. Among 7 tryptophans and 3 tyrosines in TcDyP consisting of 376 residues for the matured protein, W263, W376, and Y332 were identified as surface-exposed protein radicals. Only the W263 was also characterized as one of surface-exposed oxidation sites. SDS-PAGE and size-exclusion chromatography demonstrated that W376 represents an off-pathway destination for electron transfer, resulting in the crosslinking of proteins in the absence of substrates. Mutation of W376 improved compound I stability and overall catalytic efficiency toward RB19. While Y332 is highly conserved across all four classes of DyPs, its catalytic function in A-class TcDyP is minimal possibly due to its extremely small solvent accessible areas. Identification of surface-exposed protein radicals and substrate oxidation sites is important for understanding DyP mechanism and modulating its catalytic functions for improved activity on phenolic lignin.

Bacterial dye-decolorizing peroxidases: Biochemical properties and biotechnological opportunities

Bacterial dye-decolorizing peroxidases: Biochemical properties and biotechnological opportunities

Genome sequence of the filamentous soil fungus Chaetomium cochliodes reveals abundance of genes for heme enzymes from all peroxidase and catalase superfamilies.

BackgroundThe ascomycetous family Chaetomiaceae (class Sordariomycetes) includes numerous soilborn, saprophytic, endophytic and pathogenic fungi which can adapt to various growth conditions and living niches by providing a broad armory of oxidative and antioxidant enzymes.ResultsWe release the 34.7 Mbp draft genome of Chaetomium cochliodes CCM F-232 consisting of 6036 contigs with an average size of 5756 bp and reconstructed its phylogeny. We show that this filamentous fungus is closely related but not identical to Chaetomium globosum and Chaetomium elatum. We screened and critically analysed this genome for open reading frames coding for essential antioxidant enzymes. It is demonstrated that the genome of C. cochliodes contains genes encoding putative enzymes from all four known heme peroxidase superfamilies including bifunctional catalase-peroxidase (KatG), cytochrome c peroxidase (CcP), manganese peroxidase, two paralogs of hybrid B peroxidases (HyBpox), cyclooxygenase, linoleate diol synthase, dye-decolorizing peroxidase (DyP) of type B and three paralogs of heme thiolate peroxidases. Both KatG and DyP-type B are shown to be introduced into ascomycetes genomes by horizontal gene transfer from various bacteria. In addition, two putative large subunit secretory and two small-subunit typical catalases are found in C. cochliodes. We support our genomic findings with quantitative transcription analysis of nine peroxidase & catalase genes.ConclusionsWe delineate molecular phylogeny of five distinct gene superfamilies coding for essential heme oxidoreductases in Chaetomia and from the transcription analysis the role of this antioxidant enzymatic armory for the survival of a peculiar soil ascomycete in various harsh environments.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3111-6) contains supplementary material, which is available to authorized users.

Class P dye-decolorizing peroxidase gene: Degenerated primers design and phylogenetic analysis

Dye-decolorizing peroxidases (DyPs) were classified as a new family of heme peroxidase in 2007. Produced by various bacteria, they are the first bacterial enzymes known able to degrade lignin and dyes, for which their application in waste treatment and pretreatment of lignocellulosic biomass could be envisaged. In this work, a PCR primer pair was created and tested that enabled the detection and quantification of a wide range of bacterial genes of P class DyP in complex matrices. In addition, a phylogenetic tree was built with all available sequences of DyP genes available, offering a first overview of their presence in the bacteria kingdom.

An aryl-alcohol oxidase of Pleurotus sapidus: heterologous expression, characterization, and application in a 2-enzyme system

Aryl-alcohol oxidases (AAOs) are enzymes supporting the degradation of lignin by fungal derived class II peroxidases produced by white-rot fungi. AAOs are able to generate H2O2 as a by-product via oxidation of an aryl-alcohol into its correspondent aldehyde. In this study, an AAO was heterologously expressed in a basidiomycete host for the first time. The gene for an AAO of the white-rot fungus Pleurotus sapidus, a close relative to the oyster mushroom Pleurotus ostreatus, was cloned into an expression vector and put under control of the promotor of the glyceraldehyde-3-phosphate dehydrogenase gene 2 (gpdII) of the button mushroom Agaricus bisporus. The expression vector was transformed into the model basidiomycete Coprinopsis cinerea, and several positive transformants were obtained. The best producing transformants were grown in shake-flasks and in a stirred tank reactor reaching enzymatic activities of up to 125UL(-1) using veratryl alcohol as a substrate. The purified AAO was biochemically characterized and compared to the previously described native and recombinant AAOs from other Pleurotus species. In addition, a two-enzyme system comprising a dye-decolorizing peroxidase (DyP) from Mycetinis scorodonius and the P. sapidus AAO was successfully employed to bleach the anthraquinone dye Reactive Blue 5.

Structure of Thermobifida fusca DyP-type peroxidase and activity towards Kraft lignin and lignin model compounds

A Dyp-type peroxidase enzyme from thermophilic cellulose degrader Thermobifida fusca (TfuDyP) was investigated for catalytic ability towards lignin oxidation. TfuDyP was characterised kinetically against a range of phenolic substrates, and a compound I reaction intermediate was observed via pre-steady state kinetic analysis at λmax 404 nm. TfuDyP showed reactivity towards Kraft lignin, and was found to oxidise a β-aryl ether lignin model compound, forming an oxidised dimer. A crystal structure of TfuDyP was determined, to 1.8 Å resolution, which was found to contain a diatomic oxygen ligand bound to the heme centre, positioned close to active site residues Asp-203 and Arg-315. The structure contains two channels providing access to the heme cofactor for organic substrates and hydrogen peroxide. Site-directed mutant D203A showed no activity towards phenolic substrates, but reduced activity towards ABTS, while mutant R315Q showed no activity towards phenolic substrates, nor ABTS.

Exploring the biocatalytic potential of a DyP-type peroxidase by profiling the substrate acceptance of Thermobifida fusca DyP peroxidase

Dye-decolorizing peroxidases (DyPs) represent a new class of oxidative enzymes for which the natural substrates are largely unknown. To explore the biocatalytic potential of a DyP, we have studied the substrate acceptance profile of a robust DyP peroxidase, a DyP from Thermobifida fusca (TfuDyP). While previous work established that this bacterial peroxidase is able to act on a few reactive dyes and aromatic sulfides, this work significantly expands its substrate scope towards lignin related compounds, flavors, and various dyes.

The DyP-type peroxidase DtpA is a Tat-substrate required for GlxA maturation and morphogenesis in Streptomyces.

The filamentous bacterium Streptomyces lividans depends on the radical copper oxidase GlxA for the formation of reproductive aerial structures and, in liquid environments, for the formation of pellets. Incorporation of copper into the active site is essential for the formation of a cross-linked tyrosyl-cysteine cofactor, which is needed for enzymatic activity. In this study, we show a crucial link between GlxA maturation and a group of copper-related proteins including the chaperone Sco and a novel DyP-type peroxidase hereinafter called DtpA. Under copper-limiting conditions, the sco and dtpA deletion mutants are blocked in aerial growth and pellet formation, similarly to a glxA mutant. Western blot analysis showed that GlxA maturation is perturbed in the sco and dtpA mutants, but both maturation and morphology can by rescued by increasing the bioavailability of copper. DtpA acts as a peroxidase in the presence of GlxA and is a substrate for the twin-arginine translocation (Tat) translocation pathway. In agreement, the maturation status of GlxA is also perturbed in tat mutants, which can be compensated for by the addition of copper, thereby partially restoring their morphological defects. Our data support a model wherein a copper-trafficking pathway and Tat-dependent secretion of DtpA link to the GlxA-dependent morphogenesis pathway.

Asymmetric sulfoxidation by engineering the heme pocket of a dye-decolorizing peroxidase

By enlarging the active site of DyP, F359G stereoselectively converting methyl-phenyl sulfide (MPS) intoSmethyl-phenyl sulfoxide (MPSO) was obtained, while the parent DyP has no activity, and L357G yields racemic mixtures.

Anabaenasp. DyP-type peroxidase is a tetramer consisting of two asymmetric dimers

DyP-type peroxidases are a newly discovered family of heme peroxidases distributed from prokaryotes to eukaryotes. Recently, using a structure-based sequence alignment, we proposed the new classes, P, I and V, as substitutes for classes A, B, C, and D [Arch Biochem Biophys 2015;574:49-55]. Although many class V enzymes from eukaryotes have been characterized, only two from prokaryotes have been reported. Here, we show the crystal structure of one of these two enzymes, Anabaena sp. DyP-type peroxidase (AnaPX). AnaPX is tetramer formed from Cys224-Cys224 disulfide-linked dimers. The tetramer of wild-type AnaPX was stable at all salt concentrations tested. In contrast, the C224A mutant showed salt concentration-dependent oligomeric states: in 600 mM NaCl, it maintained a tetrameric structure, whereas in the absence of salt, it dissociated into monomers, leading to a reduction in thermostability. Although the tetramer exhibits non-crystallographic, 2-fold symmetry in the asymmetric unit, two subunits forming the Cys224-Cys224 disulfide-linked dimer are related by 165° rotation. This asymmetry creates an opening to cavities facing the inside of the tetramer, providing a pathway for hydrogen peroxide access. Finally, a phylogenetic analysis using structure-based sequence alignments showed that class V enzymes from prokaryotes, including AnaPX, are phylogenetically closely related to class V enzymes from eukaryotes.

Dyp-Type Peroxidase (DypA) from the Bioleaching Acidophilic Bacterium <i>Leptospirillum </i><i>ferriphilum</i> DSM 14647

Leptospirillum ferriphilum is an acidophilic iron-oxidizing bacterium that is relevant for chemical leaching of sulfide ores. In the extremely acidic conditions found in bioleaching operations, this microorganism deals with an abundant supply of soluble iron and other metals that might induce oxidative damage to biomolecules through the generation of reactive oxygen species (ROS). We evaluated the role of Dyp-type peroxidase in the protection against oxidative stress in L. ferriphilum DSM14647. The genetic region encoding dypA was cloned and sequenced. The predicted DypA enzyme is 295 amino acids long with an estimated molecular mass of 32.9 kDa containing a highly conserved peroxide reduction motif. Genetic complementation of catalases/peroxidases-deficient Escherichia coli cells indicated that expression of dypA from L. ferriphilum restored the resistance to hydrogen proxide to levels exhibited by the wild type strain. Exposure of L. ferriphilum to hydrogen peroxide leads to a significant transcriptional activation of dypA suggesting its involvement in the response to oxidative stress in this bacterium. This is the first Dyp-type peroxidase characterized from an acidophilic microorganism, making it a potential candidate for research in basic and applied biology.

A Dye-Decolorizing Peroxidase from Vibrio cholerae.

The dye-decolorizing peroxidase (DyP) protein from Vibrio cholerae (VcDyP) was expressed in Escherichia coli, and its DyP activity was assayed by monitoring degradation of a typical anthraquinone dye, reactive blue 19 (RB19). Its kinetic activity was obtained by fitting the data to the Michaelis-Menten equation, giving kcat and Km values of 1.3 ± 0.3 s(-1) and 50 ± 20 μM, respectively, which are comparable to those of other DyP enzymes. The enzymatic activity of VcDyP was highest at pH 4. A mutational study showed that two distal residues, Asp144 and Arg230, which are conserved in a DyP family, are essential for the DyP reaction. The crystal structure and resonance Raman spectra of VcDyP indicate the transfer of a radical from heme to the protein surface, which was supported by the formation of the intermolecular covalent bond in the reaction with H2O2. To identify the radical site, each of nine tyrosine or two tryptophan residues was substituted. It was clarified that Tyr129 and Tyr235 are in the active site of the dye degradation reaction at lower pH, while Tyr109 and Tyr133 are the sites of an intermolecular covalent bond at higher pH. VcDyP degrades RB19 at lower pH, while it loses activity under neutral or alkaline conditions because of a change in the radical transfer pathway. This finding suggests the presence of a pH-dependent switch of the radical transfer pathway, probably including His178. Although the physiological function of the DyP reaction is unclear, our findings suggest that VcDyP enhances the DyP activity to survive only when it is placed under a severe condition such as being in gastric acid.

Characterization of Dye-decolorizing Peroxidase (DyP) from Thermomonospora curvata Reveals Unique Catalytic Properties of A-type DyPs

Dye-decolorizing peroxidases (DyPs) comprise a new family of heme peroxidases, which has received much attention due to their potential applications in lignin degradation. A new DyP from Thermomonospora curvata (TcDyP) was identified and characterized. Unlike other A-type enzymes, TcDyP is highly active toward a wide range of substrates including model lignin compounds, in which the catalytic efficiency with ABTS (kcat(app)/Km(app) = (1.7 × 10(7)) m(-1) s(-1)) is close to that of fungal DyPs. Stopped-flow spectroscopy was employed to elucidate the transient intermediates as well as the catalytic cycle involving wild-type (wt) and mutant TcDyPs. Although residues Asp(220) and Arg(327) are found necessary for compound I formation, His(312) is proposed to play roles in compound II reduction. Transient kinetics of hydroquinone (HQ) oxidation by wt-TcDyP showed that conversion of the compound II to resting state is a rate-limiting step, which will explain the contradictory observation made with the aspartate mutants of A-type DyPs. Moreover, replacement of His(312) and Arg(327) has significant effects on the oligomerization and redox potential (E°') of the enzyme. Both mutants were found to promote the formation of dimeric state and to shift E°' to a more negative potential. Not only do these results reveal the unique catalytic property of the A-type DyPs, but they will also facilitate the development of these enzymes as lignin degraders.

Redox-Active Sites in Auricularia auricula-judae Dye-Decolorizing Peroxidase and Several Directed Variants: A Multifrequency EPR Study.

Peroxide-activated Auricularia auricula-judae dye-decolorizing peroxidase (DyP) forms a mixed Trp377 and Tyr337 radical, the former being responsible for oxidation of the typical DyP substrates (Linde et al. Biochem. J., 2015, 466, 253-262); however, a pure tryptophanyl radical EPR signal is detected at pH 7 (where the enzyme is inactive), in contrast with the mixed signal observed at pH for optimum activity, pH 3. On the contrary, the presence of a second tyrosine radical (at Tyr147) is deduced by a multifrequency EPR study of a variety of simple and double-directed variants (including substitution of the above and other tryptophan and tyrosine residues) at different freezing times after their activation by H2O2 (at pH 3). This points out that subsidiary long-range electron-transfer pathways enter into operation when the main pathway(s) is removed by directed mutagenesis, with catalytic efficiencies progressively decreasing. Finally, self-reduction of the Trp377 neutral radical is observed when reaction time (before freezing) is increased in the absence of reducing substrates (from 10 to 60 s). Interestingly, the tryptophanyl radical is stable in the Y147S/Y337S variant, indicating that these two tyrosine residues are involved in the self-reduction reaction.

Identification of a Novel Dye-Decolorizing Peroxidase, EfeB, Translocated by a Twin-Arginine Translocation System in Streptococcus thermophilus CGMCC 7.179.

Streptococcus thermophilus is a facultative anaerobic bacterium that has the ability to grow and survive in aerobic environments, but the mechanism for this remains unclear. In this study, the efeB gene, encoding a dye-decolorizing peroxidase, was identified in the genome of Streptococcus thermophilus CGMCC 7.179, and purified EfeB was able to decolorize reactive blue 5. Strikingly, genes encoding two components (TatA and TatC) of the twin-arginine translocation (TAT) system were also found in the same operon with the efeB gene. Knocking out efeB or tatC resulted in decreased growth of the strain under aerobic conditions, and complementation of the efeB-deficient strains with the efeB gene enhanced the biomass of the hosts only in the presence of the tatC gene. Moreover, it was proved for both S. thermophilus CGMCC 7.179 and Escherichia coli DE3 that EfeB could be translocated by the TAT system of S. thermophilus. In addition, the transcriptional levels of efeB and tatC increased when the strain was cultured under aerobic conditions. Overall, these results provide the first evidence that EfeB plays a role in protecting cells of S. thermophilus from oxidative stress, with the assistance of the TAT system.