Trp266 determines the binding specificity of a porcine aflatoxin B1 aldehyde reductase for aflatoxin B1-dialdehyde

Wu, Jun; Xu, Weiying; Zhang, Caihui; Chang, Qing; Tang, Xianqing; Li, Kangbai; Deng, Yiqun

doi:10.1016/j.bcp.2013.08.014

Cited by 12 publications

(9 citation statements)

References 35 publications

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“…Far-UV CD spectra of the recombinant CYP3A29 and the mutants were collected on a Chirascan spectrometer (Applied Photophysics, Leatherhead, UK). The measurement parameters and methods employed were described as previously [ 62 ]. The contents of the secondary structure of proteins were estimated by CONTINLL algorithm [ 40 ], which gave the smallest RMSD.…”

Section: Methodsmentioning

confidence: 99%

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Bioactivation and Regioselectivity of Pig Cytochrome P450 3A29 towards Aflatoxin B1

Chen

Zhang

et al. 2016

Toxins

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Due to unavoidable contaminations in feedstuff, pigs are easily exposed to aflatoxin B1 (AFB1) and suffer from poisoning, thus the poisoned products potentially affect human health. Heretofore, the metabolic process of AFB1 in pigs remains to be clarified, especially the principal cytochrome P450 oxidases responsible for its activation. In this study, we cloned CYP3A29 from pig liver and expressed it in Escherichia coli, and its activity has been confirmed with the typical P450 CO-reduced spectral characteristic and nifedipine-oxidizing activity. The reconstituted membrane incubation proved that the recombinant CYP3A29 was able to oxidize AFB1 to form AFB1-exo-8,9-epoxide in vitro. The structural basis for the regioselective epoxidation of AFB1 by CYP3A29 was further addressed. The T309A mutation significantly decreased the production of AFBO, whereas F304A exhibited an enhanced activation towards AFB1. In agreement with the mutagenesis study, the molecular docking simulation suggested that Thr309 played a significant role in stabilization of AFB1 binding in the active center through a hydrogen bond. In addition, the bulk phenyl group of Phe304 potentially imposed steric hindrance on the binding of AFB1. Our study demonstrates the bioactivation of pig CYP3A29 towards AFB1 in vitro, and provides the insight for understanding regioselectivity of CYP3A29 to AFB1.

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Section: Methodsmentioning

confidence: 99%

“…Samples were separated at 25 °C on a ZORBAX SB-C 18 column. The mobile phase, the gradient schedule, and detection condition were described as previously [ 62 ]. The flow rate was set to 1 mL/min, and the injection volume was 40 μL.…”

Section: Methodsmentioning

confidence: 99%

Bioactivation and Regioselectivity of Pig Cytochrome P450 3A29 towards Aflatoxin B1

Chen

Zhang

et al. 2016

Toxins

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“…Otherwise, the unconjugated AFBO is alternatively hydrolyzed to AFB1-dihydrodiol, which is reversibly converted to AFB1-dialdehyde [ 34 , 90 , 138 ]. AFB1-dialdehyde is metabolized by the enzymes of aldo-keto reductase subfamily 7 (AKR7) and microsomal epoxide hydrolase (mEH) to form the nontoxic AFB1-dialcohol metabolite in humans, rats, mice, and pigs [ 123 , 139 , 140 ].…”

Section: Biotransformation Of Mycotoxinsmentioning

confidence: 99%

“…In animals and humans, OTA can be metabolized by both phase I and phase II enzymes to many different products in the liver, kidney, and intestine ( Figure 3 ). Poor biotransformation and slow elimination of metabolites contribute to the toxicity, carcinogenicity, and organ specificity of OTA [ 139 , 141 ]. In the gut, ochratoxin α (OTα), a major metabolite and is formed by carboxypeptidases, which cleave the peptide bond in OTA [ 34 ].…”

Section: Biotransformation Of Mycotoxinsmentioning

confidence: 99%

“…Other types of major metabolites of OTA are 4-hydroxy-ochratoxin A (4-OH-OTA) and 10-hydroxyochratoxin A (10-OH-OTA) have been identified from the urine of rats and are also produced by human, pigs, goat, chicken, rat, and rabbit liver microsomes or human bronchial epithelial cells in vitro [ 142 , 143 , 144 ]. Most of the metabolites of OTA, such as OTα, OTB, 4-OH-OTA, and 10-OH-OTA, are less toxic than the original compound [ 129 , 139 ]. However, opening the lactone ring under alkaline conditions (called the lactone-opened OTA), found in rodents, leads to more toxic metabolites than OTA itself [ 126 ].…”

Section: Biotransformation Of Mycotoxinsmentioning

confidence: 99%

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Mycotoxins: Biotransformation and Bioavailability Assessment Using Caco-2 Cell Monolayer

Tran

Viktorová

Ruml

2020

Toxins

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The determination of mycotoxins content in food is not sufficient for the prediction of their potential in vivo cytotoxicity because it does not reflect their bioavailability and mutual interactions within complex matrices, which may significantly alter the toxic effects. Moreover, many mycotoxins undergo biotransformation and metabolization during the intestinal absorption process. Biotransformation is predominantly the conversion of mycotoxins meditated by cytochrome P450 and other enzymes. This should transform the toxins to nontoxic metabolites but it may possibly result in unexpectedly high toxicity. Therefore, the verification of biotransformation and bioavailability provides valuable information to correctly interpret occurrence data and biomonitoring results. Among all of the methods available, the in vitro models using monolayer formed by epithelial cells from the human colon (Caco-2 cell) have been extensively used for evaluating the permeability, bioavailability, intestinal transport, and metabolism of toxic and biologically active compounds. Here, the strengths and limitations of both in vivo and in vitro techniques used to determine bioavailability are reviewed, along with current detailed data about biotransformation of mycotoxins. Furthermore, the molecular mechanism of mycotoxin effects is also discussed regarding the disorder of intestinal barrier integrity induced by mycotoxins.

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The critical role of porcine cytochrome P450 3A46 in the bioactivation of aflatoxin B1

Jiang¹,

Wu²,

Zhang³

et al. 2018

Biochemical Pharmacology

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Trp266 determines the binding specificity of a porcine aflatoxin B1 aldehyde reductase for aflatoxin B1-dialdehyde

Cited by 12 publications

References 35 publications

Bioactivation and Regioselectivity of Pig Cytochrome P450 3A29 towards Aflatoxin B1

Bioactivation and Regioselectivity of Pig Cytochrome P450 3A29 towards Aflatoxin B1

Mycotoxins: Biotransformation and Bioavailability Assessment Using Caco-2 Cell Monolayer

The critical role of porcine cytochrome P450 3A46 in the bioactivation of aflatoxin B1

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