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Heterologous Expression of Recombinant Human Cytochrome P450 (CYP) in Escherichia coli: N-Terminal Modification, Expression, Isolation, Purification, and Reconstitution. BIOTECH 2023; 12:biotech12010017. [PMID: 36810444 PMCID: PMC9944785 DOI: 10.3390/biotech12010017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/02/2023] [Accepted: 02/03/2023] [Indexed: 02/10/2023] Open
Abstract
Cytochrome P450 (CYP) enzymes play important roles in metabolising endogenous and xenobiotic substances. Characterisations of human CYP proteins have been advanced with the rapid development of molecular technology that allows heterologous expression of human CYPs. Among several hosts, bacteria systems such as Escherichia coli (E. coli) have been widely used thanks to their ease of use, high level of protein yields, and affordable maintenance costs. However, the levels of expression in E. coli reported in the literature sometimes differ significantly. This paper aims to review several contributing factors, including N-terminal modifications, co-expression with a chaperon, selections of vectors and E. coli strains, bacteria culture and protein expression conditions, bacteria membrane preparations, CYP protein solubilizations, CYP protein purifications, and reconstitution of CYP catalytic systems. The common factors that would most likely lead to high expression of CYPs were identified and summarised. Nevertheless, each factor may still require careful evaluation for individual CYP isoforms to achieve a maximal expression level and catalytic activity. Recombinant E. coli systems have been evidenced as a useful tool in obtaining the ideal level of human CYP proteins, which ultimately allows for subsequent characterisations of structures and functions.
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Bigley AN, Harvey SP, Narindoshvili T, Raushel FM. Substrate Analogues for the Enzyme-Catalyzed Detoxification of the Organophosphate Nerve Agents-Sarin, Soman, and Cyclosarin. Biochemistry 2021; 60:2875-2887. [PMID: 34494832 DOI: 10.1021/acs.biochem.1c00361] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The G-type nerve agents, sarin (GB), soman (GD), and cyclosarin (GF), are among the most toxic compounds known. Much progress has been made in evolving the enzyme phosphotriesterase (PTE) from Pseudomonas diminuta for the decontamination of the G-agents; however, the extreme toxicity of the G-agents makes the use of substrate analogues necessary. Typical analogues utilize a chromogenic leaving group to facilitate high-throughput screening, and substitution of an O-methyl for the P-methyl group found in the G-agents, in an effort to reduce toxicity. Till date, there has been no systematic evaluation of the effects of these substitutions on catalytic activity, and the presumed reduction in toxicity has not been tested. A series of 21 G-agent analogues, including all combinations of O-methyl, p-nitrophenyl, and thiophosphate substitutions, have been synthesized and evaluated for their ability to unveil the stereoselectivity and catalytic activity of PTE variants against the authentic G-type nerve agents. The potential toxicity of these analogues was evaluated by measuring the rate of inactivation of acetylcholinesterase (AChE). All of the substitutions reduced inactivation of AChE by more than 100-fold, with the most effective being the thiophosphate analogues, which reduced the rate of inactivation by about 4-5 orders of magnitude. The analogues were found to reliably predict changes in catalytic activity and stereoselectivity of the PTE variants and led to the identification of the BHR-30 variant, which has no apparent stereoselectivity against GD and a kcat/Km of 1.4 × 106, making it the most efficient enzyme for GD decontamination reported till date.
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Affiliation(s)
- Andrew N Bigley
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Steven P Harvey
- US Army DEVCOM-CBC, FCDD-CBR-CC E3400, 5183 Blackhawk Rd. Aberdeen Proving Ground, Aberdeen, Maryland 21010, United States
| | - Tamari Narindoshvili
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Frank M Raushel
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States.,Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas 7784, United States
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Bigley AN, Desormeaux E, Xiang DF, Bae SY, Harvey SP, Raushel FM. Overcoming the Challenges of Enzyme Evolution To Adapt Phosphotriesterase for V-Agent Decontamination. Biochemistry 2019; 58:2039-2053. [DOI: 10.1021/acs.biochem.9b00097] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Andrew N. Bigley
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Emily Desormeaux
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Dao Feng Xiang
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Sue Y. Bae
- U.S. Army Edgewood Chemical Biological Center, 5183 Blackhawk Road, Aberdeen Proving Ground, Maryland 21010, United States
| | - Steven P. Harvey
- U.S. Army Edgewood Chemical Biological Center, 5183 Blackhawk Road, Aberdeen Proving Ground, Maryland 21010, United States
| | - Frank M. Raushel
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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Yamaori S, Araki N, Shionoiri M, Ikehata K, Kamijo S, Ohmori S, Watanabe K. A Specific Probe Substrate for Evaluation of CYP4A11 Activity in Human Tissue Microsomes and a Highly Selective CYP4A11 Inhibitor: Luciferin-4A and Epalrestat. J Pharmacol Exp Ther 2018; 366:446-457. [DOI: 10.1124/jpet.118.249557] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 06/29/2018] [Indexed: 02/06/2023] Open
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Goldsmith M, Tawfik DS. Enzyme engineering: reaching the maximal catalytic efficiency peak. Curr Opin Struct Biol 2017; 47:140-150. [PMID: 29035814 DOI: 10.1016/j.sbi.2017.09.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 07/04/2017] [Accepted: 09/20/2017] [Indexed: 01/01/2023]
Abstract
The practical need for highly efficient enzymes presents new challenges in enzyme engineering, in particular, the need to improve catalytic turnover (kcat) or efficiency (kcat/KM) by several orders of magnitude. However, optimizing catalysis demands navigation through complex and rugged fitness landscapes, with optimization trajectories often leading to strong diminishing returns and dead-ends. When no further improvements are observed in library screens or selections, it remains unclear whether the maximal catalytic efficiency of the enzyme (the catalytic 'fitness peak') has been reached; or perhaps, an alternative combination of mutations exists that could yield additional improvements. Here, we discuss fundamental aspects of the process of catalytic optimization, and offer practical solutions with respect to overcoming optimization plateaus.
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Affiliation(s)
- Moshe Goldsmith
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel.
| | - Dan S Tawfik
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
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Biochemical analysis of recombinant CYP4A11 allelic variant enzymes: W126R, K276T and S353G. Drug Metab Pharmacokinet 2016; 31:445-450. [DOI: 10.1016/j.dmpk.2016.09.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 08/09/2016] [Accepted: 09/12/2016] [Indexed: 11/19/2022]
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Han S, Pham TV, Kim JH, Lim YR, Park HG, Jeong D, Yun CH, Chun YJ, Kang LW, Kim D. Structural insights into the binding of lauric acid to CYP107L2 from Streptomyces avermitilis. Biochem Biophys Res Commun 2016; 482:902-908. [PMID: 27890614 DOI: 10.1016/j.bbrc.2016.11.131] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 11/24/2016] [Indexed: 01/27/2023]
Abstract
Streptomyces avermitilis is an actinobacterium known to produce clinically useful macrolides including avermectins. CYP107L2 from S. avermitilis shares a high sequence similarity with the PikC (CYP107L1) from S. venezuelae. To elucidate the structural features of CYP107L2, we conducted biochemical and structural characterization of CYP107L2 from S. avermitilis. The CYP107L2 gene was cloned, and its recombinant protein was expressed and purified. The CYP107L2 showed a low-spin state of heme, and the reduced form yielded the CO difference spectra with a maximal absorption at 449 nm. Binding of pikromycin and lauric acid yielded the typical type I spectra with Kd values of 4.8 ± 0.3 and 111 ± 9 μM, respectively. However, no metabolic product was observed in the enzyme reaction. X-ray crystal structures of the ligand-free CYP107L2 and its complex with lauric acid were determined at the resolution of 2.6 and 2.5 Å, respectively. CYP107L2 showed a well-conserved CYP structure with a wide-open substrate-binding cavity. The lauric acid is bound mainly via hydrophobic interactions with the carboxylate group of lauric acid coordinated to the heme of P450. Glu-40 and Leu-382 residues in the CYP107L2 complex with lauric acid showed significant conformational changes to provide plentiful room for the lauric acid in the substrate-binding site.
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Affiliation(s)
- Songhee Han
- Department of Biological Sciences, Konkuk University, Seoul 05025 South Korea
| | - Tan-Viet Pham
- Department of Biological Sciences, Konkuk University, Seoul 05025 South Korea; Department of Biotechnology, Institute of Biotechnology and Food Technology, Industrial University of Ho Chi Minh City, Ho Chi Minh City, Viet Nam
| | - Joo-Hwan Kim
- Department of Biological Sciences, Konkuk University, Seoul 05025 South Korea
| | - Young-Ran Lim
- Department of Biological Sciences, Konkuk University, Seoul 05025 South Korea
| | - Hyoung-Goo Park
- Department of Biological Sciences, Konkuk University, Seoul 05025 South Korea
| | - Dabin Jeong
- Department of Biological Sciences, Konkuk University, Seoul 05025 South Korea
| | - Chul-Ho Yun
- School of Biological Sciences and Technology, Chonnam National University, Gwangju 61186, South Korea
| | - Young-Jin Chun
- College of Pharmacy, Chung-Ang University, Seoul 06974, South Korea
| | - Lin-Woo Kang
- Department of Biological Sciences, Konkuk University, Seoul 05025 South Korea.
| | - Donghak Kim
- Department of Biological Sciences, Konkuk University, Seoul 05025 South Korea.
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Han S, Pham TV, Kim JH, Lim YR, Park HG, Cha GS, Yun CH, Chun YJ, Kang LW, Kim D. Structural Analysis of the Streptomyces avermitilis CYP107W1-Oligomycin A Complex and Role of the Tryptophan 178 Residue. Mol Cells 2016; 39:211-6. [PMID: 26883908 PMCID: PMC4794603 DOI: 10.14348/molcells.2016.2226] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 11/06/2015] [Accepted: 11/19/2015] [Indexed: 12/18/2022] Open
Abstract
CYP107W1 from Streptomyces avermitilis is a cytochrome P450 enzyme involved in the biosynthesis of macrolide oligomycin A. A previous study reported that CYP107W1 regioselectively hydroxylated C12 of oligomycin C to produce oligomycin A, and the crystal structure of ligand free CYP107W1 was determined. Here, we analyzed the structural properties of the CYP107W1-oligomycin A complex and characterized the functional role of the Trp178 residue in CYP107W1. The crystal structure of the CYP107W1 complex with oligomycin A was determined at a resolution of 2.6 Å. Oligomycin A is bound in the substrate access channel on the upper side of the prosthetic heme mainly by hydrophobic interactions. In particular, the Trp178 residue in the active site intercalates into the large macrolide ring, thereby guiding the substrate into the correct binding orientation for a productive P450 reaction. A Trp178 to Gly mutation resulted in the distortion of binding titration spectra with oligomycin A, whereas binding spectra with azoles were not affected. The Gly178 mutant's catalytic turnover number for the 12-hydroxylation reaction of oligomycin C was highly reduced. These results indicate that Trp178, located in the open pocket of the active site, may be a critical residue for the productive binding conformation of large macrolide substrates.
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Affiliation(s)
- Songhee Han
- Department of Biological Sciences, Konkuk University, Seoul 143-701
Korea
| | - Tan-Viet Pham
- Department of Biological Sciences, Konkuk University, Seoul 143-701
Korea
| | - Joo-Hwan Kim
- Department of Biological Sciences, Konkuk University, Seoul 143-701
Korea
| | - Young-Ran Lim
- Department of Biological Sciences, Konkuk University, Seoul 143-701
Korea
| | - Hyoung-Goo Park
- Department of Biological Sciences, Konkuk University, Seoul 143-701
Korea
| | - Gun-Su Cha
- School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757,
Korea
| | - Chul-Ho Yun
- School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757,
Korea
| | - Young-Jin Chun
- College of Pharmacy, Chung-Ang University, Seoul 156-756,
Korea
| | - Lin-Woo Kang
- Department of Biological Sciences, Konkuk University, Seoul 143-701
Korea
| | - Donghak Kim
- Department of Biological Sciences, Konkuk University, Seoul 143-701
Korea
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Ohk SO, Park HG, Lee H, Kwon YJ, Kim BJ, Kim D, Chun YJ. Heterologous expression and characterization of CYP61A1 from dandruff-causing Malassezia globosa. Protein Expr Purif 2015; 114:89-94. [PMID: 26160660 DOI: 10.1016/j.pep.2015.07.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 07/04/2015] [Accepted: 07/04/2015] [Indexed: 11/17/2022]
Abstract
Malassezia globosa is pathogenic fungus that causes skin disorders including dandruff in humans. Many yeast cytochrome CYP enzymes are involved in the biosynthesis of sterols and are considered major targets of azole antifungal agents. Here, we report on the expression and characterization of the MGL_0310 gene product (CYP61A1), a sterol C-22 desaturase in M. globosa. The open reading frame of the CYP61A1 gene was amplified by PCR from M. globosa CBS 7966 genomic DNA and cloned into a pCW vector. The CYP61A1 gene was heterologously expressed in Escherichia coli and purified using a Ni(2+)-NTA affinity column. The purified CYP61A1 protein exhibited a CO-difference spectrum typical of CYPs with a maximum absorption at 452nm. Binding spectral titration with β-sitosterol and campesterol demonstrated the type I binding mode with an increase at 411nm and a decrease at 432nm. The calculated Kd values are 5.4±0.6μM and 6.1±1.0μM for β-sitosterol and campesterol, respectively. No metabolic product, however, was observed in the CYP61A1-supported enzyme reaction with these sterols. The purified CYP61A1 protein exhibited tight binding to azole agents, suggesting that this enzyme may be a target for the pathogenic M. globosa fungus. Moreover, several fatty acids were found to bind to CYP61A1, indicating that the architecture of the enzyme includes a relatively large active site space. This study provides new insight into the biosynthesis of fungal sterols in M. globosa and a basis for the development of antifungal as potential therapeutic agents to treat dandruff.
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Affiliation(s)
- Seul-Ong Ohk
- College of Pharmacy, Chung-Ang University, Seoul 156-756, Republic of Korea
| | - Hyoung-Goo Park
- Department of Biological Sciences, Konkuk University, Seoul 143-701, Republic of Korea
| | - Hwayoun Lee
- Department of Biological Sciences, Konkuk University, Seoul 143-701, Republic of Korea
| | - Yeo-Jung Kwon
- College of Pharmacy, Chung-Ang University, Seoul 156-756, Republic of Korea
| | - Beom Joon Kim
- Department of Dermatology, College of Medicine, Chung-Ang University, Seoul 156-755, Republic of Korea
| | - Donghak Kim
- Department of Biological Sciences, Konkuk University, Seoul 143-701, Republic of Korea.
| | - Young-Jin Chun
- College of Pharmacy, Chung-Ang University, Seoul 156-756, Republic of Korea.
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Han S, Pham TV, Kim JH, Lim YR, Park HG, Cha GS, Yun CH, Chun YJ, Kang LW, Kim D. Functional characterization of CYP107W1 from Streptomyces avermitilis and biosynthesis of macrolide oligomycin A. Arch Biochem Biophys 2015; 575:1-7. [PMID: 25849761 DOI: 10.1016/j.abb.2015.03.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 03/26/2015] [Accepted: 03/31/2015] [Indexed: 02/01/2023]
Abstract
Streptomyces avermitilis contains 33 cytochrome P450 genes in its genome, many of which play important roles in the biosynthesis process of antimicrobial agents. Here, we characterized the biochemical function and structure of CYP107W1 from S. avermitilis, which is responsible for the 12-hydroxylation reaction of oligomycin C. CYP107W1 was expressed and purified from Escherichia coli. Purified proteins exhibited the typical CO-binding spectrum of P450. Interaction of oligomycin C and oligomycin A (12-hydroxylated oligomycin C) with purified CYP107W1 resulted in a type I binding with Kd values of 14.4 ± 0.7 μM and 2.0 ± 0.1 μM, respectively. LC-mass spectrometry analysis showed that CYP107W1 produced oligomycin A by regioselectively hydroxylating C12 of oligomycin C. Steady-state kinetic analysis yielded a kcat value of 0.2 min(-1) and a Km value of 18 μM. The crystal structure of CYP107W1 was determined at 2.1 Å resolution. The overall P450 folding conformations are well conserved, and the open access binding pocket for the large macrolide oligomycin C was observed above the distal side of heme. This study of CYP107W1 can help a better understanding of clinically important P450 enzymes as well as their optimization and engineering for synthesizing novel antibacterial agents and other pharmaceutically important compounds.
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Affiliation(s)
- Songhee Han
- Konkuk University, Department of Biological Sciences, Seoul 143-701, Republic of Korea
| | - Tan-Viet Pham
- Konkuk University, Department of Biological Sciences, Seoul 143-701, Republic of Korea
| | - Joo-Hwan Kim
- Konkuk University, Department of Biological Sciences, Seoul 143-701, Republic of Korea
| | - Young-Ran Lim
- Konkuk University, Department of Biological Sciences, Seoul 143-701, Republic of Korea
| | - Hyoung-Goo Park
- Konkuk University, Department of Biological Sciences, Seoul 143-701, Republic of Korea
| | - Gun-Su Cha
- Chonnam National University, School of Biological Sciences and Technology, Gwangju 500-757, Republic of Korea
| | - Chul-Ho Yun
- Chonnam National University, School of Biological Sciences and Technology, Gwangju 500-757, Republic of Korea
| | - Young-Jin Chun
- Chung-Ang University, College of Pharmacy, Seoul 156-756, Republic of Korea
| | - Lin-Woo Kang
- Konkuk University, Department of Biological Sciences, Seoul 143-701, Republic of Korea.
| | - Donghak Kim
- Konkuk University, Department of Biological Sciences, Seoul 143-701, Republic of Korea.
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Lim YR, Kim IH, Han S, Park HG, Ko MJ, Chun YJ, Yun CH, Kim D. Functional Significance of Cytochrome P450 1A2 Allelic Variants, P450 1A2*8, *15, and *16 (R456H, P42R, and R377Q). Biomol Ther (Seoul) 2015; 23:189-94. [PMID: 25767688 PMCID: PMC4354321 DOI: 10.4062/biomolther.2015.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 01/28/2015] [Accepted: 01/29/2015] [Indexed: 11/18/2022] Open
Abstract
P450 1A2 is responsible for the metabolism of clinically important drugs and the metabolic activation of environmental chemicals. Genetic variations of P450 1A2 can influence its ability to perform these functions, and thus, this study aimed to characterize the functional significance of three P450 1A2 allelic variants containing nonsynonymous single nucleotide polymorphisms (P450 1A2*8, R456H; *15, P42R; *16, R377Q). Variants containing these SNPs were constructed and the recombinant enzymes were expressed and purified in Escherichia coli. Only the P42R variant displayed the typical CO-binding spectrum indicating a P450 holoenzyme with an expression level of ∼ 170 nmol per liter culture, but no P450 spectra were observed for the two other variants. Western blot analysis revealed that the level of expression for the P42R variant was lower than that of the wild type, however the expression of variants R456H and R377Q was not detected. Enzyme kinetic analyses indicated that the P42R mutation in P450 1A2 resulted in significant changes in catalytic activities. The P42R variant displayed an increased catalytic turnover numbers (kcat) in both of methoxyresorufin O-demethylation and phenacetin O-deethylation. In the case of phenacetin O-deethylation analysis, the overall catalytic efficiency (kcat/Km) increased up to 2.5 fold with a slight increase of its Km value. This study indicated that the substitution P42R in the N-terminal proline-rich region of P450 contributed to the improvement of catalytic activity albeit the reduction of P450 structural stability or the decrease of substrate affinity. Characterization of these polymorphisms should be carefully examined in terms of the metabolism of many clinical drugs and environmental chemicals.
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Affiliation(s)
- Young-Ran Lim
- Department of Biological Sciences, Konkuk University, Seoul 143-701, Republic of Korea
| | - In-Hyeok Kim
- Department of Biological Sciences, Konkuk University, Seoul 143-701, Republic of Korea
| | - Songhee Han
- Department of Biological Sciences, Konkuk University, Seoul 143-701, Republic of Korea
| | - Hyoung-Goo Park
- Department of Biological Sciences, Konkuk University, Seoul 143-701, Republic of Korea
| | - Mi-Jung Ko
- Department of Biological Sciences, Konkuk University, Seoul 143-701, Republic of Korea
| | - Young-Jin Chun
- College of Pharmacy, Chung-Ang University, Seoul 156-756, Republic of Korea
| | - Chul-Ho Yun
- School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Donghak Kim
- Department of Biological Sciences, Konkuk University, Seoul 143-701, Republic of Korea
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Park HG, Lim YR, Han S, Kim D. Expression and Characterization of Truncated Recombinant Human Cytochrome P450 2J2. Toxicol Res 2014; 30:33-8. [PMID: 24795797 PMCID: PMC4007041 DOI: 10.5487/tr.2014.30.1.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 03/19/2014] [Accepted: 03/28/2014] [Indexed: 11/20/2022] Open
Abstract
The human cytochrome P450 2J2 catalyzes an epoxygenase reaction to oxidize various fatty acids including arachidonic acid. In this study, three recombinant enzyme constructs of P450 2J2 were heterologously expressed in Escherichia coli and their P450 proteins were successfully purified using a Ni(2+)-NTA affinity column. Deletion of 34 amino acid residues in N-terminus of P450 2J2 enzyme (2J2-D) produced the soluble enzyme located in the cytosolic fraction. The enzymatic analysis of this truncated protein indicated the typical spectral characteristics and functional properties of P450 2J2 enzyme. P450 2J2-D enzymes from soluble fraction catalyzed the oxidation reaction of terfenadine to the hydroxylated product. However, P450 2J2-D enzymes from membrane fraction did not support the P450 oxidation reaction although it displayed the characteristic CO-binding spectrum of P450. Our finding of these features in the N-terminal modified P450 2J2 enzyme could help understand the biological functions and the metabolic roles of P450 2J2 enzyme and make the crystallographic analysis of the P450 2J2 structure feasible for future studies.
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Affiliation(s)
- Hyoung-Goo Park
- Department of Biological Sciences, Konkuk University, Seoul, Korea
| | - Young-Ran Lim
- Department of Biological Sciences, Konkuk University, Seoul, Korea
| | - Songhee Han
- Department of Biological Sciences, Konkuk University, Seoul, Korea
| | - Donghak Kim
- Department of Biological Sciences, Konkuk University, Seoul, Korea
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Lee H, Kim JH, Han S, Lim YR, Park HG, Chun YJ, Park SW, Kim D. Directed-evolution analysis of human cytochrome P450 2A6 for enhanced enzymatic catalysis. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2014; 77:1409-1418. [PMID: 25343290 DOI: 10.1080/15287394.2014.951757] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Cytochrome P450 2A6 (P450 2A6) is the major enzyme responsible for the oxidation of coumarin, nicotine, and tobacco-specific nitrosamines in human liver. In this study, the catalytic turnover of coumarin oxidation was improved by directed-evolution analysis of P450 2A6 enzyme. A random mutant library was constructed using error-prone polymerase chain reaction (PCR) of the open reading frame of the P450 2A6 gene and individual mutant clones were screened for improved catalytic activity in analysis of fluorescent coumarin 7-hydroxylation. Four consecutive rounds of random mutagenesis and screening were performed and catalytically enhanced mutants were selected in each round of screening. The selected mutants showed the sequentially accumulated mutations of amino acid residues of P450 2A6: B1 (F209S), C1 (F209S, S369G), D1 (F209S, S369G, E277K), and E1 (F209S, S369G, E277K, A10V). E1 mutants displayed approximately 13-fold increased activity based on fluorescent coumarin hydroxylation assays at bacterial whole cell level. Steady-state kinetic parameters for coumarin 7-hydroxylation and nicotine oxidation were measured in purified mutant enzymes and indicated catalytic turnover numbers (kcat) of selected mutants were enhanced up to sevenfold greater than wild-type P450 2A6. However, all mutants displayed elevated Km values and therefore catalytic efficiencies (kcat/Km) were not improved. The increase in Km values was partially attributed to reduction in substrate binding affinities measured in the analysis of substrate binding titration. The structural analysis of P450 2A6 indicates that F209S mutation is sufficient to affect direct interaction of substrate at the active site.
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Affiliation(s)
- Hwayoun Lee
- a Department of Biological Sciences , Konkuk University , Seoul , Korea
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