scholarly journals 3,6-Dichlorosalicylate Catabolism Is Initiated by the DsmABC Cytochrome P450 Monooxygenase System inRhizorhabdus dicambivoransNdbn-20

2017 ◽  
Vol 84 (4) ◽  
Author(s):  
Na Li ◽  
Li Yao ◽  
Qin He ◽  
Jiguo Qiu ◽  
Dan Cheng ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Bioinformatic Analysis ◽  
Heme Iron ◽  
Cytochrome P450 Monooxygenase ◽  
Monooxygenase System ◽  
Catabolic Pathway ◽  
P450 Monooxygenase ◽  
Content Type ◽  
Promising Target

ABSTRACTThe degradation of the herbicide dicamba is initiated by demethylation to form 3,6-dichlorosalicylate (3,6-DCSA) inRhizorhabdusdicambivoransNdbn-20. In the present study, a 3,6-DCSA degradation-deficient mutant, Ndbn-20m, was screened. A cluster,dsmR1DABCEFGR2, was lost in this mutant. The cluster consisted of nine genes, all of which were apparently induced by 3,6-DCSA. DsmA shared 30 to 36% identity with the monooxygenase components of reported three-component cytochrome P450 systems and formed a monophyletic branch in the phylogenetic tree. DsmB and DsmC were most closely related to the reported [2Fe-2S] ferredoxin and ferredoxin reductase, respectively. The disruption ofdsmAin strain Ndbn-20 resulted in inactive 3,6-DCSA degradation. WhendsmABC, but notdsmAalone, was introduced into mutant Ndbn-20m andSphingobium quisquiliarumDC-2 (which is unable to degrade salicylate and its derivatives), they acquired the ability to hydroxylate 3,6-DCSA. Single-crystal X-ray diffraction demonstrated that the DsmABC-catalyzed hydroxylation occurred at the C-5 position of 3,6-DCSA, generating 3,6-dichlorogentisate (3,6-DCGA). In addition, DsmD shared 51% identity with GtdA (a gentisate and 3,6-DCGA 1,2-dioxygenase) fromSphingomonassp. strain RW5. However, unlike GtdA, the purified DsmD catalyzed the cleavage of gentisate and 3-chlorogentisate but not 6-chlorogentisate or 3,6-DCGAin vitro. Based on the bioinformatic analysis and gene function studies, a possible catabolic pathway of dicamba inR. dicambivoransNdbn-20 was proposed.IMPORTANCEDicamba is widely used to control a variety of broadleaf weeds and is a promising target herbicide for the engineering of herbicide-resistant crops. The catabolism of dicamba has thus received increasing attention. Bacteria mineralize dicamba initially via demethylation, generating 3,6-dichlorosalicylate. However, the catabolism of 3,6-dichlorosalicylate remains unknown. In this study, we cloned a gene cluster,dsmR1DABCEFGR2, involved in 3,6-dichlorosalicylate degradation fromR. dicambivoransNdbn-20, demonstrated that the cytochrome P450 monooxygenase system DsmABC was responsible for the 5-hydroxylation of 3,6-dichlorosalicylate, and proposed a dicamba catabolic pathway. This study provides a basis to elucidate the catabolism of dicamba and has benefits for the ecotoxicological study of dicamba. Furthermore, the hydroxylation of salicylate has been previously reported to be catalyzed by single-component flavoprotein or three-component Rieske non-heme iron oxygenase, whereas DsmABC was the only cytochrome P450 monooxygenase system hydroxylating salicylate and its methyl- or chloro-substituted derivatives.

scholarly journals Cytochrome P450 Initiates Degradation ofcis-Dichloroethene by Polaromonas sp. Strain JS666

2013 ◽  
Vol 79 (7) ◽  
pp. 2263-2272 ◽  
Author(s):  
Shirley F. Nishino ◽  
Kwanghee A. Shin ◽  
James M. Gossett ◽  
Jim C. Spain
Keyword(s):  
Cytochrome P450 ◽  
Heterologous Gene Expression ◽  
Degradation Mechanism ◽  
Cytochrome P450 Monooxygenase ◽  
Cytochrome P450 Enzymes ◽  
Catabolic Pathway ◽  
P450 Monooxygenase ◽  
Content Type ◽  
P450 Gene ◽  
Cell Extracts

ABSTRACTPolaromonassp. strain JS666 grows oncis-1,2-dichoroethene (cDCE) as the sole carbon and energy source under aerobic conditions, but the degradation mechanism and the enzymes involved are unknown. In this study, we established the complete pathway forcDCE degradation through heterologous gene expression, inhibition studies, enzyme assays, and analysis of intermediates. Several lines of evidence indicate that a cytochrome P450 monooxygenase catalyzes the initial step ofcDCE degradation. Both the transient accumulation of dichloroacetaldehyde incDCE-degrading cultures and dichloroacetaldehyde dehydrogenase activities in cell extracts of JS666 support a pathway for degradation ofcDCE through dichloroacetaldehyde. The mechanism minimizes the formation ofcDCE epoxide. The molecular phylogeny of the cytochrome P450 gene and the organization of neighboring genes suggest that thecDCE degradation pathway recently evolved in a progenitor capable of degrading 1,2-dichloroethane either by the recruitment of the cytochrome P450 monooxygenase gene from an alkane catabolic pathway or by selection for variants of the P450 in a preexisting 1,2-dichloroethane catabolic pathway. The results presented here add yet another role to the broad array of productive reactions catalyzed by cytochrome P450 enzymes.

scholarly journals Cytochrome P450 Monooxygenase-Mediated Metabolic Utilization of Benzo[a]Pyrene by Aspergillus Species

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Erin M. Ostrem Loss ◽  
Mi-Kyung Lee ◽  
Ming-Yueh Wu ◽  
Julia Martien ◽  
Wanping Chen ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Environmental Pollutants ◽  
Energy Generation ◽  
Fungal Species ◽  
Metabolic Changes ◽  
Cytochrome P450 Monooxygenase ◽  
Cellular Growth ◽  
P450 Monooxygenase ◽  
Content Type ◽  
Fundamental Knowledge

ABSTRACT Soil-dwelling fungal species possess the versatile metabolic capability to degrade complex organic compounds that are toxic to humans, yet the mechanisms they employ remain largely unknown. Benzo[a]pyrene (BaP) is a pervasive carcinogenic contaminant, posing a significant concern for human health. Here, we report that several Aspergillus species are capable of degrading BaP. Exposing Aspergillus nidulans cells to BaP results in transcriptomic and metabolic changes associated with cellular growth and energy generation, implying that the fungus utilizes BaP as a growth substrate. Importantly, we identify and characterize the conserved bapA gene encoding a cytochrome P450 monooxygenase that is necessary for the metabolic utilization of BaP in Aspergillus. We further demonstrate that the fungal NF-κB-type velvet regulators VeA and VelB are required for proper expression of bapA in response to nutrient limitation and BaP degradation in A. nidulans. Our study illuminates fundamental knowledge of fungal BaP metabolism and provides novel insights into enhancing bioremediation potential. IMPORTANCE We are increasingly exposed to environmental pollutants, including the carcinogen benzo[a]pyrene (BaP), which has prompted extensive research into human metabolism of toxicants. However, little is known about metabolic mechanisms employed by fungi that are able to use some toxic pollutants as the substrates for growth, leaving innocuous by-products. This study systemically demonstrates that a common soil-dwelling fungus is able to use benzo[a]pyrene as food, which results in expression and metabolic changes associated with growth and energy generation. Importantly, this study reveals key components of the metabolic utilization of BaP, notably a cytochrome P450 monooxygenase and the fungal NF-κB-type transcriptional regulators. Our study advances fundamental knowledge of fungal BaP metabolism and provides novel insight into designing and implementing enhanced bioremediation strategies.

scholarly journals Purification of Cytochrome P450 and Ferredoxin, Involved in Bisphenol A Degradation, from Sphingomonas sp. Strain AO1

2005 ◽  
Vol 71 (12) ◽  
pp. 8024-8030 ◽  
Author(s):  
Miho Sasaki ◽  
Ayako Akahira ◽  
Ko-ichi Oshiman ◽  
Tetsuaki Tsuchido ◽  
Yoshinobu Matsumura
Keyword(s):  
Mass Spectrometry ◽  
Cytochrome P450 ◽  
Bisphenol A ◽  
Cytochrome P450 Monooxygenase ◽  
Mass Spectrometry Analysis ◽  
Monooxygenase System ◽  
P450 Monooxygenase ◽  
Monooxygenase Activity ◽  
Chromatography Analysis ◽  
Ferredoxin Reductase

ABSTRACT In a previous study (M. Sasaki, J. Maki, K. Oshiman, Y. Matsumura, and T. Tsuchido, Biodegradation 16:449-459, 2005), the cytochrome P450 monooxygenase system was shown to be involved in bisphenol A (BPA) degradation by Sphingomonas sp. strain AO1. In the present investigation, we purified the components of this monooxygenase, cytochrome P450 (P450bisd), ferredoxin (Fdbisd), and ferredoxin reductase (Redbisd). We demonstrated that P450bisd and Fdbisd are homodimeric proteins with molecular masses of 102.3 and 19.1 kDa, respectively, by gel filtration chromatography analysis. Spectroscopic analysis of Fdbisd revealed the presence of a putidaredoxin-type [2Fe-2S] cluster. P450bisd, in the presence of Fdbisd, Redbisd, and NADH, was able to convert BPA. The Km and k cat values for BPA degradation were 85 ± 4.7 μM and 3.9 ± 0.04 min−1, respectively. NADPH, spinach ferredoxin, and spinach ferredoxin reductase resulted in weak monooxygenase activity. These results indicated that the electron transport system of P450bisd might exhibit strict specificity. Two BPA degradation products of the P450bisd system were detected by high-performance liquid chromatography analysis and were thought to be 1,2-bis(4-hydroxyphenyl)-2-propanol and 2,2-bis(4-hydroxyphenyl)-1-propanol based on mass spectrometry-mass spectrometry analysis. This is the first report demonstrating that the cytochrome P450 monooxygenase system in bacteria is involved in BPA degradation.

Sign in / Sign up

Export Citation Format

Share Document