CYP63A2, a Catalytically Versatile Fungal P450 Monooxygenase Capable of Oxidizing Higher-Molecular-Weight Polycyclic Aromatic Hydrocarbons, Alkylphenols, and Alkanes
ABSTRACT Cytochrome P450 monooxygenases (P450s) are known to oxidize hydrocarbons albeit with limited substrate specificity across classes of these compounds. Here we report a P450 monooxygenase (CYP63A2) from the model ligninolytic white rot fungus Phanerochaete chrysosporium that was found to possess a broad oxidizing capability toward structurally diverse hydrocarbons belonging to mutagenic/carcinogenic fused-ring higher molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs), endocrine-disrupting long-chain alkylphenols (APs), and crude oil aliphatic hydrocarbons n-alkanes. A homology-based 3D-model revealed presence of an extraordinarily large active site cavity in CYP63A2 compared to the mammalian PAH-oxidizing (CYP3A4, CYP1A2 and CYP1B1) and bacterial aliphatic hydrocarbon-oxidizing (CYP101D and CYP102A1) P450s. This structural feature in conjunction with ligand docking simulations suggested potential versatility of the enzyme. Experimental characterization using recombinantly expressed CYP63A2 revealed its ability to oxidize HMW-PAHs of varying ring size, including 4 rings (pyrene and fluoranthene), 5 rings [lsqb]benzo(a)pyrene[rsqb], and 6 rings [lsqb]benzo(ghi)perylene[rsqb]; the highest enzymatic activity being toward the 5-ring PAH followed by the 4-ring and 6-ring PAHs, in that order. CYP63A2 activity yielded monohydroxylated PAH metabolites. The enzyme was found to also act as an alkane ω-hydroxylase that oxidized varying chain-length n-alkanes (C9-C12 and C15-C19) as well as alkyl side-chains (C3-C9) in alkylphenols (APs). CYP63A2 showed preferential oxidation of long chain-length APs and alkanes. To our knowledge, this is the first of its kind P450 across biological kingdoms that possesses such broad substrate specificity toward structurally diverse xenobiotics (PAHs, APs, and alkanes), making it a potent enzyme biocatalyst candidate to handle mixed pollution (e.g., crude oil spills).
Full-textDOI: · Available from: Khajamohiddin Syed, Dec 04, 2014
- SourceAvailable from: KHM Nazmul Hussain Nazir
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- "Recent genome sequencing of fungal species revealed the presence of a large number of P450s in their genomes, with some exceptions (Moktali et al. 2012; Nelson 2011). Functional analysis of fungal P450s showed the presence of P450s displaying extraordinary catalytic activities (Syed et al. 2013b) and recently a fungal P450 has been engineered to oxidize carcinogenic and/or mutagenic compounds (Syed et al. 2013c). However, to date, P450s with a thermostable nature have not been reported from this kingdom. "
ABSTRACT: Cytochrome P450 monooxygenases (P450s) are ubiquitous heme-thiolate proteins that have potential biotechnological application. Thermostable-P450s that can withstand hostile industrial conditions, such as high temperatures, extremes of pH and organic solvents, are needed for biotechnological usage. Here, for the first time, we report a large number of thermostable-P450s from two thermophilic biomass-degrading fungi, Myceliophthora thermophila and Thielavia terrestris. Genome-wide P450 analysis revealed the presence of 79 and 70 P450s (P450ome) in T. terrestris and M. thermophila. Authentic P450s containing both the P450 signature domains (EXXR and CXG) were classified as follows: T. terrestris (50 families and 56 subfamilies) and M. thermophila (49 families and 53 subfamilies). Bioinformatics analysis of P450omes suggested the presence of a large number of thermostable-P450s. Based on aliphatic index cut-off (>90), 14 and 11 P450s were determined to be thermostable in T. terrestris and M. thermophila. Among the thermostable P450s, six P450s from T. terrestris and three from M. thermophila had a melting temperature (Tm) of >65 °C, suggesting their hyperthermal tolerance. Analysis of the instability index of two ascomycete P450omes revealed the presence of 12 and 19 in vitro stable P450s in T. terrestris and M. thermophila. Overall, six P450s from T. terrestris and four from M. thermophila showed both thermal tolerance and in vitro stability. Thermophilic ascomycetes P450s are of potential interest from a structural, mechanistic and biotechnological point of view, as five P450s showed higher thermal tolerance and five showed higher in vitro stability compared to the well-characterized thermostable-P450s CYP175A1 (bacteria) and CYP119 (archaea).Genes & genomics 01/2014; 36(3). DOI:10.1007/s13258-013-0170-9 · 0.57 Impact Factor
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- "This along with a higher concentration of 3OH-BaP (3036.84 g kg −1 ), the known P450 metabolite of BaP , in the nutrient-sufficient conditions confirmed the significant role of P450 monooxygenases under these conditions. CBD expression was higher and more sustained under nutrient-sufficient conditions, consistent with that in liquid cultures , although its role in PAH biodegradation is not clear. "
ABSTRACT: High molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) such as benzo[a]pyrene (BaP) are resistant to biodegradation in soil. Conventionally, white rot fungus Phanerochaete chrysosporium has been investigated for HMW-PAH degradation in soil primarily using nutrient-deficient (ligninolytic) conditions, albeit with limited and non-sustainable biodegradation outcomes. In this study, we report development of an alternative novel biphasic process initiated under nutrient-sufficient (non-ligninolytic) culture conditions, by employing an advanced experimental design strategy. During the initial nutrient-sufficient non-ligninolytic phase (16 days), the process showed upregulation (3.6- and 22.3-fold, respectively) of two key PAH-oxidizing P450 monooxygenases pc2 (CYP63A2) and pah4 (CYP5136A3) and formation of typical P450-hydroxylated metabolite. This along with abrogation (84.9%) of BaP degradation activity in response to a P450-specific inhibitor implied key role of these monooxygenases. The subsequent phase triggered on continued incubation (to 25 days) switched the process from non-ligninolytic to ligninolytic resulting in a significantly higher net degradation (91.6% as against 67.4% in the control nutrient-limited set) of BaP with concomitant de novo ligninolytic enzyme expression making it a biphasic process yielding improved sustainable bioremediation of PAH-contaminated soil. To our knowledge this is the first report on development of such biphasic process for bioremediation application of a white rot fungus.Journal of hazardous materials 08/2013; 261C:675-683. DOI:10.1016/j.jhazmat.2013.07.055 · 4.33 Impact Factor
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ABSTRACT: Genome sequencing of basidiomycetes, a group of fungi capable of degrading/mineralizing plant material, revealed the presence of numerous cytochrome P450 monooxygenases (P450s) in their genomes, with some exceptions. Considering the large repertoire of P450s found in fungi, it is difficult to identify P450s that play an important role in fungal metabolism and the adaptation of fungi to diverse ecological niches. In this study, we followed Sir Charles Darwin's theory of natural selection to identify such P450s in model basidiomycete fungi showing a preference for different types of plant components degradation. Any P450 family comprising a large number of member P450s compared to other P450 families indicates its natural selection over other P450 families by its important role in fungal physiology. Genome-wide comparative P450 analysis in the basidiomycete species, Phanerochaete chrysosporium, Phanerochaete carnosa, Agaricus bisporus, Postia placenta, Ganoderma sp. and Serpula lacrymans, revealed enrichment of 11 P450 families (out of 68 P450 families), CYP63, CYP512, CYP5035, CYP5037, CYP5136, CYP5141, CYP5144, CYP5146, CYP5150, CYP5348 and CYP5359. Phylogenetic analysis of the P450 family showed species-specific alignment of P450s across the P450 families with the exception of P450s of Phanerochaete chrysosporium and Phanerochaete carnosa, suggesting paralogous evolution of P450s in model basidiomycetes. P450 gene-structure analysis revealed high conservation in the size of exons and the location of introns. P450s with the same gene structure were found tandemly arranged in the genomes of selected fungi. This clearly suggests that extensive gene duplications, particularly tandem gene duplications, led to the enrichment of selective P450 families in basidiomycetes. Functional analysis and gene expression profiling data suggest that members of the P450 families are catalytically versatile and possibly involved in fungal colonization of plant material. To our knowledge, this is the first report on the identification and comparative-evolutionary analysis of P450 families enriched in model basidiomycetes.PLoS ONE 01/2014; 9(1):e86683. DOI:10.1371/journal.pone.0086683 · 3.23 Impact Factor