Characterizing Proteins of Unknown Function: Orphan Cytochrome P450 Enzymes as a Paradigm

Guengerich, F. Peter; Tang, Zhongmei; Salamanca-Pinzón, S. Giovanna; Cheng, Qian

doi:10.1124/mi.10.3.6

Cited by 37 publications

(28 citation statements)

References 83 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We studied CYP2B (mouse CYP2B10/rat CYP2B1/2), CYP3A (mouse CYP3A11/rat CYP3A2), and CYP1A2 because these isoforms have been implicated in the metabolism of polychlorinated biphenyls (Kania-Korwel et al, 2008Curran et al, 2011), polybrominated diphenyl ethers (Erratico et al, 2013;Feo et al, 2013), and organophosphorus pesticides (Tang et al, 2001;Foxenberg et al, 2007). Two orphan P450s, CYP4X1 and CYP2S1 (Guengerich et al, 2010), were also included in this study because CYP2S1 is abundantly expressed in many extrahepatic tissues (Choudhary et al, 2003) and CYP4X1 is predominantly expressed in the rodent brain (Bylund et al, 2002;Al-Anizy et al, 2006). The data reported herein demonstrate brain region-specific expression of P450s in the rodent brain that is sex-and species-dependent and generally not altered by the classic inducers phenobarbital and dexamethasone under conditions that significantly induce P450 expression in the liver.…”

Section: Introductionmentioning

confidence: 99%

“…We studied CYP2B (mouse CYP2B10/rat CYP2B1/2), CYP3A (mouse CYP3A11/rat CYP3A2), and CYP1A2 because these isoforms have been implicated in the metabolism of polychlorinated biphenyls (Kania-Korwel et al, 2008Curran et al, 2011), polybrominated diphenyl ethers (Erratico et al, 2013;Feo et al, 2013), and organophosphorus pesticides (Tang et al, 2001;Foxenberg et al, 2007). Two orphan P450s, CYP4X1 and CYP2S1 (Guengerich et al, 2010), were also included in this study because s This article has supplemental material available at dmd.aspetjournals.org.ABBREVIATIONS: CI, confidence interval; CO, corn oil; DEX, dexamethasone; P450, cytochrome P450; PB, phenobarbital. …”

mentioning

confidence: 99%

See 1 more Smart Citation

Cytochrome P450 mRNA Expression in the Rodent Brain: Species-, Sex-, and Region-Dependent Differences

Stamou

Kania-Korwel

et al. 2013

Drug Metab Dispos

View full text Add to dashboard Cite

Cytochrome P450 (P450) enzymes play a critical role in the activation and detoxication of many neurotoxic chemicals. Although research has largely focused on P450-mediated metabolism in the liver, emerging evidence suggests that brain P450s influence neurotoxicity by modulating local metabolite levels. As a first step toward better understanding the relative role of brain P450s in determining neurotoxic outcome, we characterized mRNA expression of specific P450 isoforms in the rodent brain. Adult mice (male and female) and rats (male) were treated with vehicle, phenobarbital, or dexamethasone. Transcripts for CYP2B, CYP3A, CYP1A2, and the orphan CYP4X1 and CYP2S1 were quantified in the liver, hippocampus, cortex, and cerebellum by quantitative (real-time) polymerase chain reaction. These P450s were all detected in the liver with the exception of CYP4X1, which was detected in rat but not mouse liver. P450 expression profiles in the brain varied regionally. With the exception of the hippocampus, there were no sex differences in regional brain P450 expression profiles in mice; however, there were marked species differences. In the liver, phenobarbital induced CYP2B expression in both species. Dexamethasone induced hepatic CYP2B and CYP3A in mice but not rats. In contrast, brain P450s did not respond to these classic hepatic P450 inducers. Our findings demonstrate that P450 mRNA expression in the brain varies by region, regional brain P450 profiles vary between species, and their induction varies from that of hepatic P450s. These novel data will be useful for designing mechanistic studies to examine the relative role of P450-mediated brain metabolism in neurotoxicity. IntroductionThe cytochrome P450 (P450) superfamily is a diverse group of enzymes that catalyze the oxidative metabolism of not only endogenous substrates but also xenobiotics, including environmental contaminants of significant public health concern that target the nervous system, including polychlorinated biphenyls, polybrominated diphenyl ethers, and organophosphorus pesticides (Ariyoshi et al., 1995;Foxenberg et al., 2007;Erratico et al., 2013;Feo et al., 2013). Biotransformation of these compounds by P450s can result in bioactivation or detoxication, and the balance between these activities influences the bioeffective dose, and thus the neurotoxic outcome, following environmental exposures, as shown in studies of humans and animal models (Foxenberg et al., 2007;Curran et al., 2011;Kim et al., 2011;Crane et al., 2012;Khokhar and Tyndale, 2012).Much of the research effort to characterize P450-mediated metabolism of neurotoxic compounds has focused on the liver. However, it is now evident that P450s are expressed in a number of extrahepatic tissues, including brain (Ding and Kaminsky, 2003;Ferguson and Tyndale, 2011). Although total P450 content in the human and rodent brain is generally significantly lower than that in the liver (Warner et al., 1988;Bhamre et al., 1992;Volk et al., 1995), recent evidence from rat studies demonstrates that P45...

show abstract

Section: Introductionmentioning

confidence: 99%

“…We studied CYP2B (mouse CYP2B10/rat CYP2B1/2), CYP3A (mouse CYP3A11/rat CYP3A2), and CYP1A2 because these isoforms have been implicated in the metabolism of polychlorinated biphenyls (Kania-Korwel et al, 2008Curran et al, 2011), polybrominated diphenyl ethers (Erratico et al, 2013;Feo et al, 2013), and organophosphorus pesticides (Tang et al, 2001;Foxenberg et al, 2007). Two orphan P450s, CYP4X1 and CYP2S1 (Guengerich et al, 2010), were also included in this study because s This article has supplemental material available at dmd.aspetjournals.org.ABBREVIATIONS: CI, confidence interval; CO, corn oil; DEX, dexamethasone; P450, cytochrome P450; PB, phenobarbital. …”

mentioning

confidence: 99%

Cytochrome P450 mRNA Expression in the Rodent Brain: Species-, Sex-, and Region-Dependent Differences

Stamou

Kania-Korwel

et al. 2013

Drug Metab Dispos

View full text Add to dashboard Cite

show abstract

“…For several examples given in Table 1, the terpene-hydroxylating activity of the cytochrome P450 was not described until years after the first isolation and characterization of the enzyme. This is often the case with so-called orphan P450s, for which the natural substrate is not known, or xenobiotic-degrading P450s with a broad substrate range [23]. In such circumstances, screening of compound libraries is a common method to examine the substrate range and often results in the identification of new terpenoid substrates.…”

Section: Origin and Identification Of Microbialmentioning

confidence: 99%

Terpene Hydroxylation with Microbial Cytochrome P450 Monooxygenases

Janocha

Schmitz

Bernhardt

2015

Biotechnology of Isoprenoids

View full text Add to dashboard Cite

Terpenoids comprise a highly diverse group of natural products. In addition to their basic carbon skeleton, they differ from one another in their functional groups. Functional groups attached to the carbon skeleton are the basis of the terpenoids' diverse properties. Further modifications of terpene olefins include the introduction of acyl-, aryl-, or sugar moieties and usually start with oxidations catalyzed by cytochrome P450 monooxygenases (P450s, CYPs). P450s are ubiquitously distributed throughout nature, involved in essential biological pathways such as terpenoid biosynthesis as well as the tailoring of terpenoids and other natural products. Their ability to introduce oxygen into nonactivated C-H bonds is unique and makes P450s very attractive for applications in biotechnology. Especially in the field of terpene oxidation, biotransformation methods emerge as an attractive alternative to classical chemical synthesis. For this reason, microbial P450s depict a highly interesting target for protein engineering approaches in order to increase selectivity and activity, respectively. Microbial P450s have been described to convert industrial and pharmaceutically interesting terpenoids such as ionones, limone, valencene, resin acids, and triterpenes (including steroids) as well as vitamin D3. Highly selective and active mutants have been evolved by applying classical site-directed mutagenesis as well as directed evolution of proteins. As P450s usually depend on electron transfer proteins, mutagenesis has also been applied to improve the interactions between P450s and their respective redox partners. This chapter provides an overview of terpenoid hydroxylation reactions catalyzed by bacterial P450s and highlights the achievements made by protein engineering to establish productive hydroxylation processes.

show abstract

“…Cytochrome P450 2S1 is one of the orphan P450s with unknown physiological function (Guengerich et al, 2010(Guengerich et al, , 2011. P450 2S1 mRNA can be detected in human skin and liver, and there are also reports of expression in trachea, lung, stomach, small intestine, and spleen (Guengerich et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Cytochrome P450 2S1 is Reduced by NADPH-Cytochrome P450 Reductase

Xiao¹,

Shinkyo²,

Guengerich³

2011

Drug Metab Dispos

View full text Add to dashboard Cite

ABSTRACT:Cytochrome P450 (P450) 2S1 is one of the orphan P450s without a clear physiological function. Controversy has arisen as to whether it can interact with NADPH-P450 reductase and accept electrons. The reduction of 1,4-bis{[2-(dimethylamino-N-oxide)ethyl]amino}-5,8-dihydroxyanthracene-9,10-dione (AQ4N) by P450 2S1 was confirmed, and the NADPH consumption rates were measured aerobically and anaerobically in the absence and presence of the drug. The reduction kinetics of P450 2S1 were rapid, as measured by stopped-flow kinetics. These results confirm that P450 2S1 can be reduced by NADPH-P450 reductase and suggest normal mixedfunction oxidase roles of P450 2S1 to be revealed.

show abstract

Characterizing Proteins of Unknown Function: Orphan Cytochrome P450 Enzymes as a Paradigm

Cited by 37 publications

References 83 publications

Cytochrome P450 mRNA Expression in the Rodent Brain: Species-, Sex-, and Region-Dependent Differences

Cytochrome P450 mRNA Expression in the Rodent Brain: Species-, Sex-, and Region-Dependent Differences

Terpene Hydroxylation with Microbial Cytochrome P450 Monooxygenases

Cytochrome P450 2S1 is Reduced by NADPH-Cytochrome P450 Reductase

Contact Info

Product

Resources

About