Dataset Information

Widely Distributed Bifunctional Bacterial Cytochrome P450 Enzymes Catalyze both Intramolecular C-C Bond Formation in cyclo-l-Tyr-l-Tyr and Its Coupling with Nucleobases.

ABSTRACT: Tailoring enzymes are important modification biocatalysts in natural product biosynthesis. We report herein six orthologous two-gene clusters for mycocyclosin and guatyromycine biosynthesis. Expression of the cyclodipeptide synthase genes gymA₁ -gymA₆ in Escherichia coli resulted in the formation of cyclo-l-Tyr-l-Tyr as the major product. Reconstruction of the biosynthetic pathways in Streptomyces albus and biochemical investigation proved that the cytochrome P450 enzymes GymB₁ -GymB₆ act as both intramolecular oxidases and intermolecular nucleobase transferases. They catalyze not only the oxidative C-C coupling within cyclo-l-Tyr-l-Tyr, leading to mycocyclosin, but also its connection with guanine and hypoxanthine, and are thus responsible for the formation of tyrosine-containing guatyromycines, instead of the reported tryptophan-nucleobase adducts. Phylogenetic data suggest the presence of at least 47 GymB orthologues, indicating the occurrence of a widely distributed enzyme class.

SUBMITTER: Liu J

PROVIDER: S-EPMC9401060 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature

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Widely Distributed Bifunctional Bacterial Cytochrome P450 Enzymes Catalyze both Intramolecular C-C Bond Formation in cyclo-l-Tyr-l-Tyr and Its Coupling with Nucleobases.

Liu Jing J Harken Lauritz L Yang Yiling Y Xie Xiulan X Li Shu-Ming SM

Angewandte Chemie (International ed. in English) 20220323 21

Tailoring enzymes are important modification biocatalysts in natural product biosynthesis. We report herein six orthologous two-gene clusters for mycocyclosin and guatyromycine biosynthesis. Expression of the cyclodipeptide synthase genes gymA<sub>1</sub> -gymA<sub>6</sub> in Escherichia coli resulted in the formation of cyclo-l-Tyr-l-Tyr as the major product. Reconstruction of the biosynthetic pathways in Streptomyces albus and biochemical investigation proved that the cytochrome P450 enzymes G ...[more]

PMID: 35201649

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Project description:Sunitinib is a multitargeted tyrosine kinase inhibitor associated with idiosyncratic hepatotoxicity. The mechanisms of this toxicity are unknown. We hypothesized that sunitinib undergoes metabolic activation to form chemically reactive, potentially toxic metabolites which may contribute to development of sunitinib-induced hepatotoxicity. The purpose of this study was to define the role of cytochrome P450 (P450) enzymes in sunitinib bioactivation. Metabolic incubations were performed using individual recombinant P450s, human liver microsomal fractions, and P450-selective chemical inhibitors. Glutathione (GSH) and dansylated GSH were used as trapping agents to detect reactive metabolite formation. Sunitinib metabolites were analyzed by liquid chromatography-tandem mass spectrometry. A putative quinoneimine-GSH conjugate (M5) of sunitinib was detected from trapping studies with GSH and dansyl-GSH in human liver microsomal incubations, and M5 was formed in an NADPH-dependent manner. Recombinant P450 1A2 generated the highest levels of defluorinated sunitinib (M3) and M5, with less formation by P450 3A4 and 2D6. P450 3A4 was the major enzyme forming the primary active metabolite N-desethylsunitinib (M1). In human liver microsomal incubations, P450 3A inhibitor ketoconazole reduced formation of M1 by 88%, while P450 1A2 inhibitor furafylline decreased generation of M5 by 62% compared to control levels. P450 2D6 and P450 3A inhibition also decreased M5 by 54 and 52%, respectively, compared to control. In kinetic assays, recombinant P450 1A2 showed greater efficiency for generation of M3 and M5 compared to that of P450 3A4 and 2D6. Moreover, M5 formation was 2.7-fold more efficient in human liver microsomal preparations from an individual donor with high P450 1A2 activity compared to a donor with low P450 1A2 activity. Collectively, these data suggest that P450 1A2 and 3A4 contribute to oxidative defluorination of sunitinib to generate a reactive, potentially toxic quinoneimine. Factors that alter P450 1A2 and 3A activity may affect patient risk for sunitinib toxicity.

Dataset Information

Widely Distributed Bifunctional Bacterial Cytochrome P450 Enzymes Catalyze both Intramolecular C-C Bond Formation in cyclo-l-Tyr-l-Tyr and Its Coupling with Nucleobases.

Publications

Widely Distributed Bifunctional Bacterial Cytochrome P450 Enzymes Catalyze both Intramolecular C-C Bond Formation in cyclo-l-Tyr-l-Tyr and Its Coupling with Nucleobases.

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