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Andress Huacachino A, Joo J, Narayanan N, Tehim A, Himes BE, Penning TM. Aldo-keto reductase (AKR) superfamily website and database: An update. Chem Biol Interact 2024; 398:111111. [PMID: 38878851 PMCID: PMC11232437 DOI: 10.1016/j.cbi.2024.111111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 05/09/2024] [Accepted: 06/13/2024] [Indexed: 06/23/2024]
Abstract
The aldo-keto reductase (AKR) superfamily is a large family of proteins found across the kingdoms of life. Shared features of the family include 1) structural similarities such as an (α/β)8-barrel structure, disordered loop structure, cofactor binding site, and a catalytic tetrad, and 2) the ability to catalyze the nicotinamide adenine dinucleotide (phosphate) reduced (NAD(P)H)-dependent reduction of a carbonyl group. A criteria of family membership is that the protein must have a measured function, and thus, genomic sequences suggesting the transcription of potential AKR proteins are considered pseudo-members until evidence of a functionally expressed protein is available. Currently, over 200 confirmed AKR superfamily members are reported to exist. A systematic nomenclature for the AKR superfamily exists to facilitate family and subfamily designations of the member to be communicated easily. Specifically, protein names include the root "AKR", followed by the family represented by an Arabic number, the subfamily-if one exists-represented by a letter, and finally, the individual member represented by an Arabic number. The AKR superfamily database has been dedicated to tracking and reporting the current knowledge of the AKRs since 1997, and the website was last updated in 2003. Here, we present an updated version of the website and database that were released in 2023. The database contains genetic, functional, and structural data drawn from various sources, while the website provides alignment information and family tree structure derived from bioinformatics analyses.
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Affiliation(s)
- Andrea Andress Huacachino
- Department of Biochemistry & Biophysics, University of Pennsylvania, Philadelphia, PA, 19104-6061, USA; Center of Excellence in Environmental Toxicology, University of Pennsylvania, Philadelphia, PA, 19104-6061, USA
| | - Jaehyun Joo
- Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania, Philadelphia, PA, 19104-6061, USA
| | - Nisha Narayanan
- Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania, Philadelphia, PA, 19104-6061, USA
| | - Anisha Tehim
- Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania, Philadelphia, PA, 19104-6061, USA
| | - Blanca E Himes
- Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania, Philadelphia, PA, 19104-6061, USA; Center of Excellence in Environmental Toxicology, University of Pennsylvania, Philadelphia, PA, 19104-6061, USA
| | - Trevor M Penning
- Center of Excellence in Environmental Toxicology, University of Pennsylvania, Philadelphia, PA, 19104-6061, USA; Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA, 19104-6061, USA.
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Xiao Z, Zha J, Yang X, Huang T, Huang S, Liu Q, Wang X, Zhong J, Zheng J, Liang R, Deng Z, Zhang J, Lin S, Dai S. A three-level regulatory mechanism of the aldo-keto reductase subfamily AKR12D. Nat Commun 2024; 15:2128. [PMID: 38459030 PMCID: PMC10923870 DOI: 10.1038/s41467-024-46363-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 02/23/2024] [Indexed: 03/10/2024] Open
Abstract
Modulation of protein function through allosteric regulation is central in biology, but biomacromolecular systems involving multiple subunits and ligands may exhibit complex regulatory mechanisms at different levels, which remain poorly understood. Here, we discover an aldo-keto reductase termed AKRtyl and present its three-level regulatory mechanism. Specifically, by combining steady-state and transient kinetics, X-ray crystallography and molecular dynamics simulation, we demonstrate that AKRtyl exhibits a positive synergy mediated by an unusual Monod-Wyman-Changeux (MWC) paradigm of allosteric regulation at low concentrations of the cofactor NADPH, but an inhibitory effect at high concentrations is observed. While the substrate tylosin binds at a remote allosteric site with positive cooperativity. We further reveal that these regulatory mechanisms are conserved in AKR12D subfamily, and that substrate cooperativity is common in AKRs across three kingdoms of life. This work provides an intriguing example for understanding complex allosteric regulatory networks.
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Affiliation(s)
- Zhihong Xiao
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Jinyin Zha
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Xu Yang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Tingting Huang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Shuxin Huang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Qi Liu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Xiaozheng Wang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Jie Zhong
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Jianting Zheng
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Rubing Liang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Zixin Deng
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Jian Zhang
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
| | - Shuangjun Lin
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
- Haihe Laboratory of Synthetic Biology, Tianjin, 300308, China.
- Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Shaobo Dai
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
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Akbary Z, Yu H, Lorenzo I, Paez K, Lee ND, DeBeVoise K, Moses J, Sanders N, Connors N, Cassano A. Electron withdrawing group-dependent substrate inhibition of an α-ketoamide reductase from Saccharomyces cerevisiae. Biochem Biophys Res Commun 2023; 676:97-102. [PMID: 37499370 DOI: 10.1016/j.bbrc.2023.07.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 07/14/2023] [Indexed: 07/29/2023]
Abstract
Aldo-keto reductases remain enzymes of interest in biocatalysis due to their ability to reduce carbonyls to alcohols stereospecifically. Based on genomic sequence, we identified aldo-keto reductases of a S. cerevisiae strain extracted from an ancient amber sample. One of the putative enzymes, AKR 163, displays 99% identity with α-amide ketoreductases from the S288C and YJM248 S. cerevisiae strains, which have been investigated for biocatalytic applications. To further investigate AKR 163, we successfully cloned, expressed in E.coli as a glutathione-S-transferase fusion protein, and affinity purified AKR 163. Kinetic studies revealed that AKR 163 experiences strong substrate inhibition by substrates containing halogen atoms or other electron withdrawing groups adjacent to the reactive carbonyl, with Ki values ranging from 0.29 to 0.6 mM and KM values ranging from 0.38 to 0.9 mM at pH 8.0. Substrates without electron withdrawing groups do not display substrate inhibition kinetics and possess much larger KM values between 83 and 260 mM under the same conditions. The kcat values ranged from 0.5 to 2.5s-1 for substrates exhibiting substrate inhibition and 0.22 to 0.52s-1 for substrates that do not engage in substrate inhibition. Overall, the results are consistent with rate-limiting dissociation of the NADP+ cofactor after hydride transfer when electron withdrawing groups are present and activating the reduction step. This process leads to a buildup of enzyme-NADP+ complex that is susceptible to binding and inhibition by a second substrate molecule.
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Affiliation(s)
- Zarina Akbary
- Program in Biochemistry and Molecular Biology, Drew University, 36 Madison Ave, Madison, NJ, 07940, United States
| | - Honglin Yu
- Program in Biochemistry and Molecular Biology, Drew University, 36 Madison Ave, Madison, NJ, 07940, United States
| | - Ivelisse Lorenzo
- Department of Biology, Drew University, 36 Madison Ave, Madison, NJ, 07940, United States
| | - Karyme Paez
- Program in Biochemistry and Molecular Biology, Drew University, 36 Madison Ave, Madison, NJ, 07940, United States
| | - Narisa Diana Lee
- Program in Biochemistry and Molecular Biology, Drew University, 36 Madison Ave, Madison, NJ, 07940, United States
| | - Kayla DeBeVoise
- Department of Biology, Drew University, 36 Madison Ave, Madison, NJ, 07940, United States
| | - Joel Moses
- Program in Biochemistry and Molecular Biology, Drew University, 36 Madison Ave, Madison, NJ, 07940, United States
| | - Nathaniel Sanders
- Program in Biochemistry and Molecular Biology, Drew University, 36 Madison Ave, Madison, NJ, 07940, United States
| | - Neal Connors
- Research Institute for Scientists Emeriti, Drew University, 36 Madison Ave, Madison, NJ, 07940, United States
| | - Adam Cassano
- Program in Biochemistry and Molecular Biology, Drew University, 36 Madison Ave, Madison, NJ, 07940, United States; Department of Chemistry, Drew University, 36 Madison Ave, Madison, NJ, 07940, United States.
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Penning TM. Steroid 5β-reductase (AKR1D1): Purification and characterization. Methods Enzymol 2023; 689:277-301. [PMID: 37802574 PMCID: PMC10655862 DOI: 10.1016/bs.mie.2023.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
In mammals there are two 3-oxo-4-ene steroid reductases that generate either A/B-trans or A/B cis-ring junctions in the steroid nucleus known as steroid 5α- and 5β- reductases, respectively. There is only one steroid 5β- reductase in each species and these are members of the aldo-keto-reductase (AKR) protein superfamily. The corresponding human enzyme is AKR1D1, and it plays an essential role in bile-acid biosynthesis. Germline mutations in AKR1D1 give rise to bile-acid deficiency. Because of its central role in steroid metabolism and need for detailed structure-function studies there is a need to purify the enzyme to homogeneity and in high yield. We report the purification of milligram amounts of crystallographic quality homogeneous recombinant protein for structure-function studies and its characterization.
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Affiliation(s)
- Trevor M Penning
- Center of Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, United States; Department of Systems Pharmacology & Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, United States.
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Detlefsen AJ, Paulukinas RD, Penning TM. Germline Mutations in Steroid Metabolizing Enzymes: A Focus on Steroid Transforming Aldo-Keto Reductases. Int J Mol Sci 2023; 24:1873. [PMID: 36768194 PMCID: PMC9915212 DOI: 10.3390/ijms24031873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 01/15/2023] [Accepted: 01/16/2023] [Indexed: 01/20/2023] Open
Abstract
Steroid hormones synchronize a variety of functions throughout all stages of life. Importantly, steroid hormone-transforming enzymes are ultimately responsible for the regulation of these potent signaling molecules. Germline mutations that cause dysfunction in these enzymes cause a variety of endocrine disorders. Mutations in SRD5A2, HSD17B3, and HSD3B2 genes that lead to disordered sexual development, salt wasting, and other severe disorders provide a glimpse of the impacts of mutations in steroid hormone transforming enzymes. In a departure from these established examples, this review examines disease-associated germline coding mutations in steroid-transforming members of the human aldo-keto reductase (AKR) superfamily. We consider two main categories of missense mutations: those resulting from nonsynonymous single nucleotide polymorphisms (nsSNPs) and cases resulting from familial inherited base pair substitutions. We found mutations in human AKR1C genes that disrupt androgen metabolism, which can affect male sexual development and exacerbate prostate cancer and polycystic ovary syndrome (PCOS). Others may be disease causal in the AKR1D1 gene that is responsible for bile acid deficiency. However, given the extensive roles of AKRs in steroid metabolism, we predict that with expanding publicly available data and analysis tools, there is still much to be uncovered regarding germline AKR mutations in disease.
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Affiliation(s)
- Andrea J. Detlefsen
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ryan D. Paulukinas
- Department of Systems Pharmacology & Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Center of Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Trevor M. Penning
- Department of Systems Pharmacology & Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Center of Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Su AL, Mesaros CA, Krzeminski J, El-Bayoumy K, Penning TM. Role of Human Aldo-Keto Reductases in the Nitroreduction of 1-Nitropyrene and 1,8-Dinitropyrene. Chem Res Toxicol 2022; 35:2296-2309. [PMID: 36399404 PMCID: PMC9772043 DOI: 10.1021/acs.chemrestox.2c00271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
1-Nitropyrene (1-NP) and 1,8-dinitropyrene (1,8-DNP) are diesel exhaust constituents and are classified by the International Agency for Research on Cancer as probable (Group 2A) or possible (Group 2B) human carcinogens. These nitroarenes undergo metabolic activation by nitroreduction to result in the formation of DNA adducts. Human aldo-keto reductases (AKRs) 1C1-1C3 catalyze the nitroreduction of 3-nitrobenzanthrone (3-nitro-7H-benz[de]anthracen-7-one, 3-NBA), but the extent of AKR contribution toward the nitroreduction of additional nitroarenes, including 1-NP and 1,8-DNP, is currently unknown. In the present study, we investigated the ability of human recombinant AKRs to catalyze 1-NP and 1,8-DNP nitroreduction by measuring the formation of the respective six-electron reduced amine products in discontinuous ultraviolet-reverse phase high-performance liquid chromatography enzymatic assays. We found that AKR1C1-1C3 were able to catalyze the formation of 1-aminopyrene (1-AP) and 1-amino-8-nitropyrene (1,8-ANP) in our reactions with 1-NP and 1,8-DNP, respectively. We determined kinetic parameters (Km, kcat, and kcat/Km) and found that out of the three isoforms, AKR1C1 had the highest catalytic efficiency (kcat/Km) for 1-AP formation, whereas AKR1C3 had the highest catalytic efficiency for 1,8-ANP formation. Use of ultra-performance liquid chromatography high-resolution mass spectrometry verified amine product identity and provided evidence for the formation of nitroso- and hydroxylamino-intermediates in our reactions. Our study expands the role of AKR1C1-1C3, which are expressed in human lung cells, in the metabolic activation of nitroarenes that can lead to DNA adduct formation, mutation, and carcinogenesis.
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Affiliation(s)
- Anthony L Su
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Clementina A Mesaros
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Center of Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Jacek Krzeminski
- Department of Pharmacology, Penn State College of Medicine, Pennsylvania State University, Hershey Pennsylvania 17033-2360, United States
| | - Karam El-Bayoumy
- Department of Biochemistry & Molecular Biology, Penn State College of Medicine, Pennsylvania State University, Hershey Pennsylvania 17033-2360, United States
| | - Trevor M Penning
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Center of Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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Penning TM, Su AL, El-Bayoumy K. Nitroreduction: A Critical Metabolic Pathway for Drugs, Environmental Pollutants, and Explosives. Chem Res Toxicol 2022; 35:1747-1765. [PMID: 36044734 PMCID: PMC9703362 DOI: 10.1021/acs.chemrestox.2c00175] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Nitro group containing xenobiotics include drugs, cancer chemotherapeutic agents, carcinogens (e.g., nitroarenes and aristolochic acid) and explosives. The nitro group undergoes a six-electron reduction to form sequentially the nitroso-, N-hydroxylamino- and amino-functional groups. These reactions are catalyzed by nitroreductases which, rather than being enzymes with this sole function, are enzymes hijacked for their propensity to donate electrons to the nitro group either one at a time via a radical mechanism or two at time via the equivalent of a hydride transfer. These enzymes include: NADPH-dependent flavoenzymes (NADPH: P450 oxidoreductase, NAD(P)H-quinone oxidoreductase), P450 enzymes, oxidases (aldehyde oxidase, xanthine oxidase) and aldo-keto reductases. The hydroxylamino group once formed can undergo conjugation reactions with acetate or sulfate catalyzed by N-acetyltransferases or sulfotransferases, respectively, leading to the formation of intermediates containing a good leaving group which in turn can generate a nitrenium or carbenium ion for covalent DNA adduct formation. The intermediates in the reduction sequence are also prone to oxidation and produce reactive oxygen species. As a consequence, many nitro-containing xenobiotics can be genotoxic either by forming stable covalent adducts or by oxidatively damaging DNA. This review will focus on the general chemistry of nitroreduction, the enzymes responsible, the reduction of xenobiotic substrates, the regulation of nitroreductases, the ability of nitrocompounds to form DNA adducts and act as mutagens as well as some future directions.
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Affiliation(s)
| | | | - Karam El-Bayoumy
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Pennsylvania State University, Hershey, Pennsylvania 17033-2360, United States
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Overview of human 20 alpha-hydroxysteroid dehydrogenase (AKR1C1): Functions, regulation, and structural insights of inhibitors. Chem Biol Interact 2021; 351:109746. [PMID: 34780792 DOI: 10.1016/j.cbi.2021.109746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/28/2021] [Accepted: 11/10/2021] [Indexed: 11/22/2022]
Abstract
Human aldo-keto reductase family 1C1 (AKR1C1) is an important enzyme involved in human hormone metabolism, which is mainly responsible for the metabolism of progesterone in the human body. AKR1C1 is highly expressed and has an important relationship with the occurrence and development of various diseases, especially some cancers related to hormone metabolism. Nowadays, many inhibitors against AKR1C1 have been discovered, including some synthetic compounds and natural products, which have certain inhibitory activity against AKR1C1 at the target level. Here we briefly reviewed the physiological and pathological functions of AKR1C1 and the relationship with the disease, and then summarized the development of AKR1C1 inhibitors, elucidated the interaction between inhibitors and AKR1C1 through molecular docking results and existing co-crystal structures. Finally, we discussed the design ideals of selective AKR1C1 inhibitors from the perspective of AKR1C1 structure, discussed the prospects of AKR1C1 in the treatment of human diseases in terms of biomarkers, pre-receptor regulation and single nucleotide polymorphisms, aiming to provide new ideas for drug research targeting AKR1C1.
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Zhang Y, Li X, Xu D, Wu M, Dai Y, Xia M, Wang D. Cloning and characterization of steroid 5β-reductase from the venom gland of Bufo bufo gargarizans. Int J Biol Macromol 2021; 175:67-78. [PMID: 33548318 DOI: 10.1016/j.ijbiomac.2021.01.211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 01/29/2021] [Accepted: 01/30/2021] [Indexed: 12/01/2022]
Abstract
Bufadienolides are the main active ingredients of Venenum Bufonis, which is a widely used traditional Chinese medicine secreted from parotoid gland and skin glands of Bufo bufo gargarizans. According to the transcriptome analysis, "cholesterol-bile acid-bufadienolidies pathway" was proposed as animal-derived bufadienolides biosynthesis pathway by us previously. In this pathway 3β-hydroxysteroid dehydrogenase (3βHSD) and steroid 5β-reductase (SRD5β) might be the key enzymes to convert the A/B ring to cis-configuration. Therefore, as the second report of our group, here we report the cloning of the full length of SRD5β cDNA of B. bufo gargarizans (Bbg-SRD5β) from the parotoid gland of B. bufo gargarizans for the first time, and site-directed mutagenesis was used to explored the character of Bbg-SRD5β. Bbg-SRD5β had an open reading frame of 981 bp and encoded 326 amino acids residues. The expression conditions of the recombinant Bbg-SRD5β in E. coli BL21 (DE3) harbored with pCold-Bbg-SRD5β was optimized as induction for 10 h at 15 °C with 0.1 mM IPTG. With NADPH as a cofactor, Bbg-SRD5β can reduce the Δ4,5 double bonds of progesterone to generate dihydroprogesterone õwithout substrate inhibition effect. The catalytic rate of mutant type Bbg-SRD5β-Y132G was 1.8 times higher than that of wild type Bbg-SRD5β. Although Bbg-SRD5β was almost unable to reduce the progesterone to dihydroprogesterone after mutation of V309, the affinity of enzyme with NADPH changed significantly. Bbg-SRD5β is the key enzymes to convert the A/B ring of steroid to cis-configuration, and V309 is a key site affecting the binding affinity of enzyme with NADPH, and the mutation of Y132 can adjust the catalytic rate of Bbg-SRD5β.
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Affiliation(s)
- Yanan Zhang
- School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Benxi 117004, China
| | - Xue Li
- School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Benxi 117004, China
| | - Di Xu
- School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Benxi 117004, China
| | - Mengyun Wu
- School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Benxi 117004, China
| | - Yinghui Dai
- School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Benxi 117004, China
| | - Mingyu Xia
- School of Life Science and Biological Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, China.
| | - Dong Wang
- School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Benxi 117004, China.
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Songsiriritthigul C, Narawongsanont R, Tantitadapitak C, Guan HH, Chen CJ. Structure-function study of AKR4C14, an aldo-keto reductase from Thai jasmine rice (Oryza sativa L. ssp. indica cv. KDML105). ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2020; 76:472-483. [PMID: 32355043 DOI: 10.1107/s2059798320004313] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 03/30/2020] [Indexed: 11/10/2022]
Abstract
Aldo-keto reductases (AKRs) are NADPH/NADP+-dependent oxidoreductase enzymes that metabolize an aldehyde/ketone to the corresponding alcohol. AKR4C14 from rice exhibits a much higher efficiency in metabolizing malondialdehyde (MDA) than do the Arabidopsis enzymes AKR4C8 and AKR4C9, despite sharing greater than 60% amino-acid sequence identity. This study confirms the role of rice AKR4C14 in the detoxification of methylglyoxal and MDA, and demonstrates that the endogenous contents of both aldehydes in transgenic Arabidopsis ectopically expressing AKR4C14 are significantly lower than their levels in the wild type. The apo structure of indica rice AKR4C14 was also determined in the absence of the cofactor, revealing the stabilized open conformation. This is the first crystal structure in AKR subfamily 4C from rice to be observed in the apo form (without bound NADP+). The refined AKR4C14 structure reveals a stabilized open conformation of loop B, suggesting the initial phase prior to cofactor binding. Based on the X-ray crystal structure, the substrate- and cofactor-binding pockets of AKR4C14 are formed by loops A, B, C and β1α1. Moreover, the residues Ser211 and Asn220 on loop B are proposed as the hinge residues that are responsible for conformational alteration while the cofactor binds. The open conformation of loop B is proposed to involve Phe216 pointing out from the cofactor-binding site and the opening of the safety belt. Structural comparison with other AKRs in subfamily 4C emphasizes the role of the substrate-channel wall, consisting of Trp24, Trp115, Tyr206, Phe216, Leu291 and Phe295, in substrate discrimination. In particular, Leu291 could contribute greatly to substrate selectivity, explaining the preference of AKR4C14 for its straight-chain aldehyde substrate.
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Affiliation(s)
- Chomphunuch Songsiriritthigul
- Synchrotron Light Research Institute (Public Organization), 111 University Avenue, Nakhon Ratchasima 30000, Thailand
| | - Rawint Narawongsanont
- Department of Biochemistry, Faculty of Science, Kasetsart University, Pahonyothin Road, Bangkok 10903, Thailand
| | - Chonticha Tantitadapitak
- Department of Biochemistry, Faculty of Science, Kasetsart University, Pahonyothin Road, Bangkok 10903, Thailand
| | - Hong Hsiang Guan
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu 30076, Taiwan
| | - Chun Jung Chen
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu 30076, Taiwan
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Yu H, Qiu S, Cheng F, Cheng YN, Wang YJ, Zheng YG. Improving the catalytic efficiency of aldo-keto reductase KmAKR towards t-butyl 6-cyano-(3R,5R)-dihydroxyhexanoate via semi-rational design. Bioorg Chem 2019; 90:103018. [DOI: 10.1016/j.bioorg.2019.103018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 05/25/2019] [Accepted: 05/28/2019] [Indexed: 01/08/2023]
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12
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Penning TM. AKR1C3 (type 5 17β-hydroxysteroid dehydrogenase/prostaglandin F synthase): Roles in malignancy and endocrine disorders. Mol Cell Endocrinol 2019; 489:82-91. [PMID: 30012349 PMCID: PMC6422768 DOI: 10.1016/j.mce.2018.07.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 06/12/2018] [Accepted: 07/03/2018] [Indexed: 12/11/2022]
Abstract
Aldo-Keto-Reductase 1C3 (type 5 17β-hydroxysteroid dehydrogenase (HSD)/prostaglandin (PG) F2α synthase) is the only 17β-HSD that is not a short-chain dehydrogenase/reductase. By acting as a 17-ketosteroid reductase, AKR1C3 produces potent androgens in peripheral tissues which activate the androgen receptor (AR) or act as substrates for aromatase. AKR1C3 is implicated in the production of androgens in castration-resistant prostate cancer (CRPC) and polycystic ovarian syndrome; and is implicated in the production of aromatase substrates in breast cancer. By acting as an 11-ketoprostaglandin reductase, AKR1C3 generates 11β-PGF2α to activate the FP receptor and deprives peroxisome proliferator activator receptorγ of its putative PGJ2 ligands. These growth stimulatory signals implicate AKR1C3 in non-hormonal dependent malignancies e.g. acute myeloid leukemia (AML). AKR1C3 moonlights by acting as a co-activator of the AR and stabilizes ubiquitin ligases. AKR1C3 inhibitors have been used clinically for CRPC and AML and can be used to probe its pluripotency.
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Affiliation(s)
- Trevor M Penning
- Department of Systems Pharmacology and Translational Therapeutics and Center of Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, 1315 BRBII/III 421 Curie Blvd, Philadelphia, PA, 19104, USA.
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13
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Penning TM, Wangtrakuldee P, Auchus RJ. Structural and Functional Biology of Aldo-Keto Reductase Steroid-Transforming Enzymes. Endocr Rev 2019; 40:447-475. [PMID: 30137266 PMCID: PMC6405412 DOI: 10.1210/er.2018-00089] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 06/05/2018] [Indexed: 12/19/2022]
Abstract
Aldo-keto reductases (AKRs) are monomeric NAD(P)(H)-dependent oxidoreductases that play pivotal roles in the biosynthesis and metabolism of steroids in humans. AKR1C enzymes acting as 3-ketosteroid, 17-ketosteroid, and 20-ketosteroid reductases are involved in the prereceptor regulation of ligands for the androgen, estrogen, and progesterone receptors and are considered drug targets to treat steroid hormone-dependent malignancies and endocrine disorders. In contrast, AKR1D1 is the only known steroid 5β-reductase and is essential for bile-acid biosynthesis, the generation of ligands for the farnesoid X receptor, and the 5β-dihydrosteroids that have their own biological activity. In this review we discuss the crystal structures of these AKRs, their kinetic and catalytic mechanisms, AKR genomics (gene expression, splice variants, polymorphic variants, and inherited genetic deficiencies), distribution in steroid target tissues, roles in steroid hormone action and disease, and inhibitor design.
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Affiliation(s)
- Trevor M Penning
- Center of Excellence in Environmental Toxicology, Perelman School of Medicine University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine University of Pennsylvania, Philadelphia, Pennsylvania
| | - Phumvadee Wangtrakuldee
- Center of Excellence in Environmental Toxicology, Perelman School of Medicine University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine University of Pennsylvania, Philadelphia, Pennsylvania
| | - Richard J Auchus
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine and Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, Michigan
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Akintunde J, Irondi A, Ajani E, Olayemi T. Diet formulated with black seed flour activates regulatory androgenic enzymes and neuroendocrine hormones in leachate-exposed reproductive damage of rat testes. JOURNAL OF NUTRITION & INTERMEDIARY METABOLISM 2019. [DOI: 10.1016/j.jnim.2019.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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15
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Rational design of Kluyveromyces marxianus ZJB14056 aldo–keto reductase Km AKR to enhance diastereoselectivity and activity. Enzyme Microb Technol 2017; 107:32-40. [DOI: 10.1016/j.enzmictec.2017.07.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 07/10/2017] [Accepted: 07/29/2017] [Indexed: 11/21/2022]
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16
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Blaisse MR, Dong H, Fu B, Chang MCY. Discovery and Engineering of Pathways for Production of α-Branched Organic Acids. J Am Chem Soc 2017; 139:14526-14532. [PMID: 28990776 DOI: 10.1021/jacs.7b07400] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Cell-based synthesis offers many opportunities for preparing small molecules from simple renewable carbon sources by telescoping multiple reactions into a single fermentation step. One challenge in this area is the development of enzymatic carbon-carbon bond forming cycles that enable a modular disconnection of a target structure into cellular building blocks. In this regard, synthetic pathways based on thiolase enzymes to catalyze the initial carbon-carbon bond forming step between acyl coenzyme A (CoA) substrates offer a versatile route for biological synthesis, but the substrate diversity of such pathways is currently limited. In this report, we describe the identification and biochemical characterization of a thiolase-ketoreductase pair involved in production of branched acids in the roundworm, Ascaris suum, that demonstrates selectivity for forming products with an α-methyl branch using a propionyl-CoA extender unit. Engineering synthetic pathways for production of α-methyl acids in Escherichia coli using these enzymes allows the construction of microbial strains that produce either chiral 2-methyl-3-hydroxy acids (1.1 ± 0.2 g L-1) or branched enoic acids (1.12 ± 0.06 g L-1) in the presence of a dehydratase at 44% and 87% yield of fed propionate, respectively. In vitro characterization along with in vivo analysis indicates that the ketoreductase is the key driver for selectivity, forming predominantly α-branched products even when paired with a thiolase that highly prefers unbranched linear products. Our results expand the utility of thiolase-based pathways and provide biosynthetic access to α-branched compounds as precursors for polymers and other chemicals.
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Affiliation(s)
- Michael R Blaisse
- Department of Chemistry, University of California, Berkeley , Berkeley, California 94720-1460, United States
| | - Hongjun Dong
- Department of Chemistry, University of California, Berkeley , Berkeley, California 94720-1460, United States
| | - Beverly Fu
- Department of Chemistry, University of California, Berkeley , Berkeley, California 94720-1460, United States
| | - Michelle C Y Chang
- Department of Chemistry, University of California, Berkeley , Berkeley, California 94720-1460, United States.,Department of Molecular and Cell Biology, University of California, Berkeley , Berkeley, California 94720-1460, United States
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17
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Solanki K, Abdallah W, Banta S. Engineering the cofactor specificity of an alcohol dehydrogenase via single mutations or insertions distal to the 2'-phosphate group of NADP(H). Protein Eng Des Sel 2017; 30:373-380. [PMID: 28201792 DOI: 10.1093/protein/gzx009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 01/25/2017] [Indexed: 01/04/2023] Open
Abstract
There have been many reports exploring the engineering of the cofactor specificity of aldo-keto reductases (AKRs), as this class of proteins is ubiquitous and exhibits many useful activities. A common approach is the mutagenesis of amino acids involved in interactions with the 2'-phosphate group of NADP(H) in the cofactor binding pocket. We recently performed a 'loop-grafting' approach to engineer the substrate specificity of the thermostable alcohol dehydrogenase D (AdhD) from Pyrococcus furiosus and we found that a loop insertion after residue 211, which is on the back side of the cofactor binding pocket, could also alter cofactor specificity. Here, we further explore this approach by introducing single point mutations and single amino acid insertions at the loop insertion site. Six different mutants of AdhD were created by either converting glycine 211 to cysteine or serine or by inserting alanine, serine, glycine or cysteine between the 211 and 212 residues. Several mutants gained activity with NADP+ above the wild-type enzyme. And remarkably, it was found that all of the mutants investigated resulted in some degree of reversal of cofactor specificity in the oxidative direction. These changes were generally a result of changes in conformations of the ternary enzyme/cofactor/substrate complexes as opposed to changes in affinities or binding energies of the cofactors. This study highlights the role that amino acids which are distal to the cofactor binding pocket but are involved in substrate interactions can influence cofactor specificity in AdhD, and this strategy should translate to other AKR family members.
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Affiliation(s)
- Kusum Solanki
- Department of Chemical Engineering, Columbia University in the City of New York, New York, NY 10027, USA
| | - Walaa Abdallah
- Department of Chemical Engineering, Columbia University in the City of New York, New York, NY 10027, USA
| | - Scott Banta
- Department of Chemical Engineering, Columbia University in the City of New York, New York, NY 10027, USA
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18
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Impact of nonsynonymous single nucleotide polymorphisms on in-vitro metabolism of exemestane by hepatic cytosolic reductases. Pharmacogenet Genomics 2017; 26:370-80. [PMID: 27111237 DOI: 10.1097/fpc.0000000000000226] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
OBJECTIVE Exemestane (EXE) is a potent third-generation aromatase inhibitor used as endocrine therapy in breast cancer treatment and prevention. Characterization of its metabolic pathway is incomplete, with ambiguity existing in the identity of enzymes driving the production of its key metabolite, 17β-dihydroexemestane (17β-DHE). The impact of genetic variation on EXE metabolism is also unknown. This study aims to describe cytosolic reductase involvement in hepatic EXE metabolism and to assess the impact of functional polymorphisms on metabolite production. MATERIALS AND METHODS Phase I metabolites were identified in incubations of EXE with pooled human liver cytosol or recombinant protein for AKR1Cs and CBR1. Kinetic parameters characterizing EXE reduction were measured for purified wild-type enzymes, and nonsynonymous variants occurring at greater than 1% minor allele frequency using UPLC/MS/MS. RESULTS Human liver cytosol, CBR1, AKR1C1, AKR1C2, AKR1C3, and AKR1C4 reduce EXE to active primary metabolite 17β-DHE. The formation of a novel metabolite, 17α-DHE, was catalyzed by recombinant AKR1C4 and CBR1 in addition to hepatic cytosol. Variants AKR1C3 Arg258Cys and AKR1C4 Gly135Glu had significantly decreased affinity for EXE relative to their respective wild types. Five common AKR1C3 polymorphisms were associated with decreased rates of catalysis, whereas AKR1C4 Gly135Glu increased the velocity of EXE reduction. CONCLUSION AKR1Cs and CBR1 catalyze EXE reduction in vitro. These results imply that cytosolic ketosteroid reductases may participate in the EXE metabolic pathway in vivo. In addition, several common variants were associated with altered enzymatic activity, suggesting that functional polymorphisms could play an important role in overall EXE metabolism and activity by altering the extent and duration of 17β-DHE exposure.
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Penning TM. Single-molecule enzymology of steroid transforming enzymes: Transient kinetic studies and what they tell us. J Steroid Biochem Mol Biol 2016; 161:5-12. [PMID: 26596239 PMCID: PMC4842339 DOI: 10.1016/j.jsbmb.2015.10.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 10/02/2015] [Accepted: 10/15/2015] [Indexed: 01/21/2023]
Abstract
Structure-function studies on steroid transforming enzymes often use site-directed mutagenesis to inform mechanisms of catalysis and effects on steroid binding, and data are reported in terms of changes in steady state kinetic parameters kcat, Km and kcat/Km. However, this dissection of function is limited since kcat is governed by the rate-determining step and Km is a complex macroscopic kinetic constant. Often site-directed mutagenesis can lead to a change in the rate-determining step which cannot be revealed by just reporting a decrease in kcat alone. These issues are made more complex when it is considered that many steroid transforming enzymes have more than one substrate and product. We present the case for using transient-kinetics performed with stopped-flow spectrometry to assign rate constants to discrete steps in these multi-substrate reactions and their use to interpret enzyme mechanism and the effects of disease and engineered mutations. We demonstrate that fluorescence kinetic transients can be used to measure ligand binding that may be accompanied by isomerization steps, revealing the existence of new enzyme intermediates. We also demonstrate that single-turnover reactions can provide a klim for the chemical step and Ks for steroid-substrate binding and that when coupled with kinetic isotope effect measurements can provide information on transition state intermediates. We also demonstrate how multiple turnover experiments can provide evidence for either "burst-phase" kinetics, which can reveal a slow product release step, or linear-phase kinetics, in which the chemical step can be rate-determining. With these assignments it becomes more straightforward to analyze the effects of mutations. We use examples from the hydroxysteroid dehydrogenases (AKR1Cs) and human steroid 5β-reductase (AKR1D1) to illustrate the utility of the approach, which are members of the aldo-keto reductase (AKR) superfamily.
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Affiliation(s)
- Trevor M Penning
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6160, United States.
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20
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Giuseppe POD, Santos MLD, Sousa SMD, Koch KE, Yunes JA, Aparicio R, Murakami MT. A comparative structural analysis reveals distinctive features of co-factor binding and substrate specificity in plant aldo-keto reductases. Biochem Biophys Res Commun 2016; 474:696-701. [PMID: 27154221 DOI: 10.1016/j.bbrc.2016.05.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 05/02/2016] [Indexed: 11/15/2022]
Abstract
Plant aldo-keto reductases of the AKR4C subfamily play key roles during stress and are attractive targets for developing stress-tolerant crops. However, these AKR4Cs show little to no activity with previously-envisioned sugar substrates. We hypothesized a structural basis for the distinctive cofactor binding and substrate specificity of these plant enzymes. To test this, we solved the crystal structure of a novel AKR4C subfamily member, the AKR4C7 from maize, in the apo form and in complex with NADP(+). The binary complex revealed an intermediate state of cofactor binding that preceded closure of Loop B, and also indicated that conformational changes upon substrate binding are required to induce a catalytically-favorable conformation of the active-site pocket. Comparative structural analyses of homologues (AKR1B1, AKR4C8 and AKR4C9) showed that evolutionary redesign of plant AKR4Cs weakened interactions that stabilize the closed conformation of Loop B. This in turn decreased cofactor affinity and altered configuration of the substrate-binding site. We propose that these structural modifications contribute to impairment of sugar reductase activity in favor of other substrates in the plant AKR4C subgroup, and that catalysis involves a three-step process relevant to other AKRs.
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Affiliation(s)
- Priscila Oliveira de Giuseppe
- Biosciences National Laboratory (LNBio), National Center for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil
| | - Marcelo Leite Dos Santos
- Laboratory of Structural Biology and Crystallography, Institute of Chemistry, University of Campinas, Campinas, SP, Brazil
| | | | - Karen E Koch
- Department of Horticultural Science, University of Florida, Gainesville, FL, USA
| | - José Andrés Yunes
- Centro Infantil Boldrini, Campinas, SP, Brazil; Department of Medical Genetics, Faculty of Medical Sciences, University of Campinas, Campinas, SP, Brazil
| | - Ricardo Aparicio
- Laboratory of Structural Biology and Crystallography, Institute of Chemistry, University of Campinas, Campinas, SP, Brazil.
| | - Mario Tyago Murakami
- Biosciences National Laboratory (LNBio), National Center for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil.
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21
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Chen M, Jin Y, Penning TM. In-Depth Dissection of the P133R Mutation in Steroid 5β-Reductase (AKR1D1): A Molecular Basis of Bile Acid Deficiency. Biochemistry 2015; 54:6343-51. [PMID: 26418565 DOI: 10.1021/acs.biochem.5b00816] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Human steroid-5β-reductase (aldo-keto reductase 1D1, AKR1D1) stereospecifically reduces Δ(4)-3-ketosteroids to 5β-dihydrosteroids and is essential for steroid hormone metabolism and bile acid biosynthesis. Genetic defects in AKR1D1 cause bile acid deficiency that leads to life threatening neonatal hepatitis and cholestasis. The disease-associated P133R mutation caused significant decreases in catalytic efficiency with both the representative steroid (cortisone) and the bile acid precursor (7α-hydroxycholest-4-en-3-one) substrates. Pro133 is a second shell residue to the steroid binding channel and is distal to both the cofactor binding site and the catalytic center. Strikingly, the P133R mutation caused over a 40-fold increase in Kd values for the NADP(H) cofactors and increased the rate of release of NADP(+) from the enzyme by 2 orders of magnitude when compared to the wild type enzyme. By contrast the effect of the mutation on Kd values for steroids were 10-fold or less. The reduced affinity for the cofactor suggests that the mutant exists largely in the less stable cofactor-free form in the cell. Using stopped-flow spectroscopy, a significant reduction in the rate of the chemical step was observed in multiple turnover reactions catalyzed by the P133R mutant, possibly due to the altered position of NADPH. Thus, impaired NADPH binding and hydride transfer is the molecular basis for bile acid deficiency in patients with the P133R mutation. Results revealed that optimal cofactor binding is vulnerable to distant structural perturbation, which may apply to other disease-associated mutations in AKR1D1, all of which occur at conserved residues and are unstable.
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Affiliation(s)
- Mo Chen
- Center of Excellence in Environmental Toxicology and Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine University of Pennsylvania , Philadelphia, Philadelphia, United States
| | - Yi Jin
- Center of Excellence in Environmental Toxicology and Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine University of Pennsylvania , Philadelphia, Philadelphia, United States
| | - Trevor M Penning
- Center of Excellence in Environmental Toxicology and Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine University of Pennsylvania , Philadelphia, Philadelphia, United States
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Penning TM, Chen M, Jin Y. Promiscuity and diversity in 3-ketosteroid reductases. J Steroid Biochem Mol Biol 2015; 151:93-101. [PMID: 25500069 PMCID: PMC4458445 DOI: 10.1016/j.jsbmb.2014.12.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 12/03/2014] [Accepted: 12/07/2014] [Indexed: 12/16/2022]
Abstract
Many steroid hormones contain a Δ(4)-3-ketosteroid functionality that undergoes sequential reduction by 5α- or 5β- steroid reductases to produce 5α- or 5β-dihydrosteroids; and a subsequent 3-keto-reduction to produce a series of isomeric tetrahydrosteroids. Apart from steroid 5α-reductase all the remaining enzymes involved in the two step reduction process in humans belong to the aldo-keto reductase (AKR) superfamily. The enzymes involved in 3-ketosteroid reduction are AKR1C1-AKR1C4. These enzymes are promiscuous and also catalyze 20-keto- and 17-keto-steroid reduction. Interest in these reactions exist since they regulate steroid hormone metabolism in the liver, and in steroid target tissues, they may regulate steroid hormone receptor occupancy. In addition many of the dihydrosteroids are not biologically inert. The same enzymes are also involved in the metabolism of synthetic steroids e.g., hormone replacement therapeutics, contraceptive agents and inhaled glucocorticoids, and may regulate drug efficacy at their cognate receptors. This article reviews these reactions and the structural basis for substrate diversity in AKR1C1-AKR1C4, ketosteroid reductases. This article is part of a Special Issue entitled 'Steroid/Sterol signaling'.
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Affiliation(s)
- Trevor M Penning
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology & Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6160, USA.
| | - Mo Chen
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology & Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6160, USA
| | - Yi Jin
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology & Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6160, USA
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Penning TM. The aldo-keto reductases (AKRs): Overview. Chem Biol Interact 2015; 234:236-46. [PMID: 25304492 PMCID: PMC4388799 DOI: 10.1016/j.cbi.2014.09.024] [Citation(s) in RCA: 293] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 09/12/2014] [Accepted: 09/24/2014] [Indexed: 12/23/2022]
Abstract
The aldo-keto reductase (AKR) protein superfamily contains >190 members that fall into 16 families and are found in all phyla. These enzymes reduce carbonyl substrates such as: sugar aldehydes; keto-steroids, keto-prostaglandins, retinals, quinones, and lipid peroxidation by-products. Exceptions include the reduction of steroid double bonds catalyzed by AKR1D enzymes (5β-reductases); and the oxidation of proximate carcinogen trans-dihydrodiol polycyclic aromatic hydrocarbons; while the β-subunits of potassium gated ion channels (AKR6 family) control Kv channel opening. AKRs are usually 37kDa monomers, have an (α/β)8-barrel motif, display large loops at the back of the barrel which govern substrate specificity, and have a conserved cofactor binding domain. AKRs catalyze an ordered bi bi kinetic mechanism in which NAD(P)H cofactor binds first and leaves last. In enzymes that favor NADPH, the rate of release of NADP(+) is governed by a slow isomerization step which places an upper limit on kcat. AKRs retain a conserved catalytic tetrad consisting of Tyr55, Asp50, Lys84, and His117 (AKR1C9 numbering). There is conservation of the catalytic mechanism with short-chain dehydrogenases/reductases (SDRs) even though they show different protein folds. There are 15 human AKRs of these AKR1B1, AKR1C1-1C3, AKR1D1, and AKR1B10 have been implicated in diabetic complications, steroid hormone dependent malignancies, bile acid deficiency and defects in retinoic acid signaling, respectively. Inhibitor programs exist world-wide to target each of these enzymes to treat the aforementioned disorders. Inherited mutations in AKR1C and AKR1D1 enzymes are implicated in defects in the development of male genitalia and bile acid deficiency, respectively, and occur in evolutionarily conserved amino acids. The human AKRs have a large number of nsSNPs and splice variants, but in many instances functional genomics is lacking. AKRs and their variants are now poised to be interrogated using modern genomic and informatics approaches to determine their association with human health and disease.
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Affiliation(s)
- Trevor M Penning
- Center of Excellence in Environmental Toxicology, Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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Chen M, Jin Y, Penning TM. The rate-determining steps of aldo-keto reductases (AKRs), a study on human steroid 5β-reductase (AKR1D1). Chem Biol Interact 2014; 234:360-5. [PMID: 25500266 DOI: 10.1016/j.cbi.2014.12.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 12/02/2014] [Indexed: 11/25/2022]
Abstract
Aldo-keto reductases (AKRs) are an expanding family of NAD(P)(H)-dependent oxidoreductases that catalyze the reduction of either carbonyl groups or α,β-unsaturated ketones on a variety of endogenous and exogenous substrates. The enzymes catalyze a sequential ordered bi-bi kinetic mechanism, in which cofactor is bound first and released last. Using human steroid 5β-reductase (AKR1D1) as a representative enzyme, the influence of substrate structure on the rate-limiting steps of AKR catalysis has been previously determined. The rate of the chemistry step was found to differ by two orders of magnitude when different steroid substrates were used in single turnover experiments with AKR1D1. This difference was reflected in multiple turnover experiments. C17-C21 steroid substrates exhibited a fast chemistry step followed by slow product release as suggested by "burst" phase kinetics. By contrast, C27 steroids have a slower chemical step that determines the rate of the reaction and "burst-phase" kinetics are no longer observed. Here we present single turnover kinetic experiments and find that they support the existence of two different binding poses for fast substrates due to their biphasic nature. We also re-interpret the loss of "burst-phase" kinetics in the multiple turnover experiments as due to long range effects of the steroid side-chain interacting with distal parts of the steroid pocket to perturb the reaction trajectory for hydride transfer and thus reduce kcat. The ability of steroid structure and hence binding pose to influence rate determination in steroid transforming AKRs is discussed as a general phenomenon.
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Affiliation(s)
- Mo Chen
- Center of Excellence in Environmental Toxicology and Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Yi Jin
- Center of Excellence in Environmental Toxicology and Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Trevor M Penning
- Center of Excellence in Environmental Toxicology and Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA.
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Rate of steroid double-bond reduction catalysed by the human steroid 5β-reductase (AKR1D1) is sensitive to steroid structure: implications for steroid metabolism and bile acid synthesis. Biochem J 2014; 462:163-71. [PMID: 24894951 DOI: 10.1042/bj20140220] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Human AKR1D1 (steroid 5β-reductase/aldo-keto reductase 1D1) catalyses the stereospecific reduction of double bonds in Δ4-3-oxosteroids, a unique reaction that introduces a 90° bend at the A/B ring fusion to yield 5β-dihydrosteroids. AKR1D1 is the only enzyme capable of steroid 5β-reduction in humans and plays critical physiological roles. In steroid hormone metabolism, AKR1D1 serves mainly to inactivate the major classes of steroid hormones. AKR1D1 also catalyses key steps of the biosynthetic pathway of bile acids, which regulate lipid emulsification and cholesterol homoeostasis. Interestingly, AKR1D1 displayed a 20-fold variation in the kcat values, with steroid hormone substrates (e.g. aldosterone, testosterone and cortisone) having significantly higher kcat values than steroids with longer side chains (e.g. 7α-hydroxycholestenone, a bile acid precursor). Transient kinetic analysis revealed striking variations up to two orders of magnitude in the rate of the chemistry step (kchem), which resulted in different rate determining steps for the fast and slow substrates. By contrast, similar Kd values were observed for representative fast and slow substrates, suggesting similar rates of release for different steroid products. The release of NADP+ was shown to control the overall turnover for fast substrates, but not for slow substrates. Despite having high kchem values with steroid hormones, the kinetic control of AKR1D1 is consistent with the enzyme catalysing the slowest step in the catabolic sequence of steroid hormone transformation in the liver. The inherent slowness of the conversion of the bile acid precursor by AKR1D1 is also indicative of a regulatory role in bile acid synthesis.
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Yadav R, Prasad R. Identification and functional characterization of sorbitol-6-phosphate dehydrogenase protein from rice and structural elucidation by in silico approach. PLANTA 2014; 240:223-238. [PMID: 24817585 DOI: 10.1007/s00425-014-2076-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 04/08/2014] [Indexed: 06/03/2023]
Abstract
The sorbitol-6-phosphate dehydrogenase (S6PDH) is a key enzyme for sorbitol synthesis and plays an important role in the alleviation of salinity stress in plants. Despite the huge significance, the structure and the mode of action of this enzyme are still not known. In the present study, sequence analysis, cloning, expression, activity assays and enzyme kinetics using various substrates (glucose-6-phosphate, sorbitol-6-phosphate and mannose-6-phosphate) were performed to establish the functional role of S6PDH protein from rice (Oryza sativa). For the structural analysis of the protein, a comparative homology model was prepared on the basis of percentage sequence identity and substrate similarity using the crystal structure of human aldose reductase in complex with glucose-6-phosphate and NADP(+) (PDB ID: 2ACQ) as a template. Molecular docking was performed for studying the structural details of substrate binding and possible enzyme mechanism. The cloned sequence resulted into an active recombinant protein when expressed into a bacterial expression system. The purified recombinant protein was found to be active with glucose-6-phosphate and sorbitol-6-phosphate; however, activity against mannose-6-phosphate was not found. The K m values for glucose-6-phosphate and sorbitol-6-phosphate were found to be 15.9 ± 0.2 and 7.21 ± 0.5 mM, respectively. A molecular-level analysis of the active site of OsS6PDH provides valuable information about the enzyme mechanism and requisite enantioselectivity for its physiological substrates. Thus, the fundamental studies of structure and function of OsS6PDH could serve as the basis for the future studies of bio-catalytic applications of this enzyme.
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Affiliation(s)
- Rajbala Yadav
- Molecular Biology and Proteomics Lab, Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India,
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Chen M, Penning TM. 5β-Reduced steroids and human Δ(4)-3-ketosteroid 5β-reductase (AKR1D1). Steroids 2014; 83:17-26. [PMID: 24513054 PMCID: PMC3971473 DOI: 10.1016/j.steroids.2014.01.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 01/11/2014] [Accepted: 01/22/2014] [Indexed: 12/19/2022]
Abstract
5β-Reduced steroids are non-planar steroids that have a 90° bend in their structure to create an A/B cis-ring junction. This novel property is required for bile-acids to act as emulsifiers, but in addition 5β-reduced steroids have remarkable physiology and may act as potent tocolytic agents, endogenous cardiac glycosides, neurosteroids, and can act as ligands for orphan and membrane bound receptors. In humans there is only a single 5β-reductase gene AKR1D1, which encodes Δ(4)-3-ketosteroid-5β-reductase (AKR1D1). This enzyme is a member of the aldo-keto reductase superfamily, but possesses an altered catalytic tetrad, in which Glu120 replaces the conserved His residue. This predominant liver enzyme generates all 5β-dihydrosteroids in the C19-C27 steroid series. Mutations exist in the AKR1D1 gene, which result in loss of protein stability and are causative in bile-acid deficiency.
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Affiliation(s)
- Mo Chen
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6160, United States
| | - Trevor M Penning
- Center of Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6160, United States; Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6160, United States.
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28
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Rižner TL, Penning TM. Role of aldo-keto reductase family 1 (AKR1) enzymes in human steroid metabolism. Steroids 2014; 79:49-63. [PMID: 24189185 PMCID: PMC3870468 DOI: 10.1016/j.steroids.2013.10.012] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 10/16/2013] [Accepted: 10/24/2013] [Indexed: 12/30/2022]
Abstract
Human aldo-keto reductases AKR1C1-AKR1C4 and AKR1D1 play essential roles in the metabolism of all steroid hormones, the biosynthesis of neurosteroids and bile acids, the metabolism of conjugated steroids, and synthetic therapeutic steroids. These enzymes catalyze NADPH dependent reductions at the C3, C5, C17 and C20 positions on the steroid nucleus and side-chain. AKR1C1-AKR1C4 act as 3-keto, 17-keto and 20-ketosteroid reductases to varying extents, while AKR1D1 acts as the sole Δ(4)-3-ketosteroid-5β-reductase (steroid 5β-reductase) in humans. AKR1 enzymes control the concentrations of active ligands for nuclear receptors and control their ligand occupancy and trans-activation, they also regulate the amount of neurosteroids that can modulate the activity of GABAA and NMDA receptors. As such they are involved in the pre-receptor regulation of nuclear and membrane bound receptors. Altered expression of individual AKR1C genes is related to development of prostate, breast, and endometrial cancer. Mutations in AKR1C1 and AKR1C4 are responsible for sexual development dysgenesis and mutations in AKR1D1 are causative in bile-acid deficiency.
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Affiliation(s)
- Tea Lanišnik Rižner
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Slovenia.
| | - Trevor M Penning
- Center of Excellence in Environmental Toxicology, Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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Beranič N, Stefane B, Brus B, Gobec S, Rižner TL. New enzymatic assay for the AKR1C enzymes. Chem Biol Interact 2012; 202:204-9. [PMID: 23261716 DOI: 10.1016/j.cbi.2012.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 12/04/2012] [Accepted: 12/09/2012] [Indexed: 11/30/2022]
Abstract
The imbalance in expression of the human aldo-keto reductases AKR1C1-AKR1C3 is related to different hormone dependent and independent cancers and some other diseases. The AKR1C1-3 enzymes thus represent emerging targets for the development of new drugs. Currently, various enzymatic assays are used in the search for AKR1C inhibitors, and consequently the results of different research groups are not necessarily comparable. During our recent search for AKR1C inhibitors, we found a cyclopentanol derivative (2-(4-chlorobenzylidene)cyclopentanol, CBCP-ol) and its respective cyclopentanone counterpart (2-(4-chlorobenzylidene)cyclopentanone, CBCP-one) that acted as AKR1C substrates. We determined the kinetic parameters KM, kcat and kcat/KM for oxidation of CBCP-ol and reduction of CBCP-one by AKR1C enzymes in the presence of NAD(+)/NADP(+) and NADH/NADPH, respectively. The catalytic efficiencies for the oxidation of CBCP-ol in the presence of NAD(+) or NADP(+) were in general higher when compared to the catalytic efficiencies for reduction of CBCP-one in the presence of NADH or NADPH. When NADPH was used, as compared to NADH, the reductions of CBCP-one by AKR1C1, AKR1C2 and AKR1C3 were 14-, 51- and 31-fold more efficient, respectively. When comparing to oxidations of the well-known artificial substrates, 1-acenaphthenol and S-tetralol, we observed similar catalytic efficiencies as for CBCP-ol oxidation with NAD(+) and NADP(+). The comparison of CBCP-one reduction with NADPH to reductions of physiological substrates revealed in general higher efficiencies, except for reduction of 9-cis-retinaldehyde by AKR1C3. This NADPH-dependent reduction of CBCP-one was then used to re-evaluate inhibitory potencies of the known inhibitors of the target AKR1C3 and the anti-target AKR1C2, medroxyprogesterone acetate and ursodeoxycholic acid, respectively, showing Ki constants similar to the reported values. Our data thus confirm that the new enzymatic assays with two cyclopentane substrates CBP-ol and CBP-one, and especially reduction of CBCP-one with NADPH, are appropriate for the evaluation of AKR1C inhibitors.
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Affiliation(s)
- Nataša Beranič
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
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Campbell E, Chuang S, Banta S. Modular exchange of substrate-binding loops alters both substrate and cofactor specificity in a member of the aldo-keto reductase superfamily. Protein Eng Des Sel 2012; 26:181-6. [PMID: 23175796 DOI: 10.1093/protein/gzs095] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Substrate specificity in the aldo-keto reductase (AKR) superfamily is determined by three mobile loops positioned at the top of the canonical (α/β)(8)-barrel structure. These loops have previously been demonstrated to be modular in a well-studied class of AKRs, in that exchanging loops between two similar hydroxysteroid dehydrogenases resulted in a complete alteration of substrate specificity (Ma,H. and Penning,T.M. (1999) Proc. Natl Acad. Sci. USA, 96, 11161-11166). Here, we further examine the modularity of these loops by grafting those from human aldose reductase (hAR) into the hyperthermostable AKR, alcohol dehydrogenase D (AdhD), from Pyrococcus furiosus. Replacement of Loops A and B was sufficient to impart hAR activity into AdhD, and the resulting chimera retained the thermostability of the parent enzyme. However, no active chimeras were observed when the hAR loops were grafted into a previously engineered cofactor specificity mutant of AdhD, which displayed similar kinetics to hAR with the model substrate dl-glyceraldehyde. The non-additivity of these mutations suggests that efficient turnover is more dependent on the relative positioning of the cofactor and substrate in the active site than on binding of the individual species. The ability to impart the substrate specificities of mesostable AKRs into a thermostable scaffold will be useful in a variety of applications including immobilized enzyme systems for bioelectrocatalysis and fine chemical synthesis.
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Affiliation(s)
- Elliot Campbell
- Department of Chemical Engineering, Columbia University in the City of New York, New York, NY 10027, USA
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31
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Shultz CA, Quinn AM, Park JH, Harvey RG, Bolton JL, Maser E, Penning TM. Specificity of human aldo-keto reductases, NAD(P)H:quinone oxidoreductase, and carbonyl reductases to redox-cycle polycyclic aromatic hydrocarbon diones and 4-hydroxyequilenin-o-quinone. Chem Res Toxicol 2011; 24:2153-66. [PMID: 21910479 DOI: 10.1021/tx200294c] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are suspect human lung carcinogens and can be metabolically activated to remote quinones, for example, benzo[a]pyrene-1,6-dione (B[a]P-1,6-dione) and B[a]P-3,6-dione by the action of either P450 monooxygenase or peroxidases, and to non-K region o-quinones, for example B[a]P-7,8-dione, by the action of aldo keto reductases (AKRs). B[a]P-7,8-dione also structurally resembles 4-hydroxyequilenin o-quinone. These three classes of quinones can redox cycle, generate reactive oxygen species (ROS), and produce the mutagenic lesion 8-oxo-dGuo and may contribute to PAH- and estrogen-induced carcinogenesis. We compared the ability of a complete panel of human recombinant AKRs to catalyze the reduction of PAH o-quinones in the phenanthrene, chrysene, pyrene, and anthracene series. The specific activities for NADPH-dependent quinone reduction were often 100-1000 times greater than the ability of the same AKR isoform to oxidize the cognate PAH-trans-dihydrodiol. However, the AKR with the highest quinone reductase activity for a particular PAH o-quinone was not always identical to the AKR isoform with the highest dihydrodiol dehydrogenase activity for the respective PAH-trans-dihydrodiol. Discrete AKRs also catalyzed the reduction of B[a]P-1,6-dione, B[a]P-3,6-dione, and 4-hydroxyequilenin o-quinone. Concurrent measurements of oxygen consumption, superoxide anion, and hydrogen peroxide formation established that ROS were produced as a result of the redox cycling. When compared with human recombinant NAD(P)H:quinone oxidoreductase (NQO1) and carbonyl reductases (CBR1 and CBR3), NQO1 was a superior catalyst of these reactions followed by AKRs and last CBR1 and CBR3. In A549 cells, two-electron reduction of PAH o-quinones causes intracellular ROS formation. ROS formation was unaffected by the addition of dicumarol, suggesting that NQO1 is not responsible for the two-electron reduction observed and does not offer protection against ROS formation from PAH o-quinones.
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Affiliation(s)
- Carol A Shultz
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Mohler JL, Titus MA, Wilson EM. Potential prostate cancer drug target: bioactivation of androstanediol by conversion to dihydrotestosterone. Clin Cancer Res 2011; 17:5844-9. [PMID: 21705451 DOI: 10.1158/1078-0432.ccr-11-0644] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
High-affinity binding of dihydrotestosterone (DHT) to the androgen receptor (AR) initiates androgen-dependent gene activation, required for normal male sex development in utero, and contributes to prostate cancer development and progression in men. Under normal physiologic conditions, DHT is synthesized predominantly by 5α-reduction of testosterone, the major circulating androgen produced by the testis. During androgen deprivation therapy, intratumoral androgen production is sufficient for AR activation and prostate cancer growth, even though circulating testicular androgen levels are low. Recent studies indicate that the metabolism of 5α-androstane-3α, 17β-diol by 17β-hydroxysteroid dehydrogenase 6 in benign prostate and prostate cancer cells is a major biosynthetic pathway for intratumoral synthesis of DHT, which binds AR and initiates transactivation to promote prostate cancer growth during androgen deprivation therapy. Drugs that target the so-called backdoor pathway of DHT synthesis provide an opportunity to enhance clinical response to luteinizing-hormone-releasing hormone (LHRH) agonists or antagonists, AR antagonists, and inhibitors of 5α-reductase enzymes (finasteride or dutasteride), and other steroid metabolism enzyme inhibitors (ketoconazole or the recently available abiraterone acetate).
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Affiliation(s)
- James L Mohler
- Department of Urology, Roswell Park Cancer Institute, Department of Urology, University at Buffalo, State University of New York, Buffalo, New York, USA
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33
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Penning TM. Human hydroxysteroid dehydrogenases and pre-receptor regulation: insights into inhibitor design and evaluation. J Steroid Biochem Mol Biol 2011; 125:46-56. [PMID: 21272640 PMCID: PMC3104102 DOI: 10.1016/j.jsbmb.2011.01.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 01/18/2011] [Accepted: 01/18/2011] [Indexed: 11/16/2022]
Abstract
Hydroxysteroid dehydrogenases (HSDs) represent a major class of NAD(P)(H) dependent steroid hormone oxidoreductases involved in the pre-receptor regulation of hormone action. This is achieved by HSDs working in pairs so that they can interconvert ketosteroids with hydroxysteroids resulting in a change in ligand potency for nuclear receptors. HSDs belong to two protein superfamilies the aldo-keto reductases and the short-chain dehydrogenase/reductases. In humans, many of the important enzymes have been thoroughly characterized including the elucidation of their three-dimensional structures. Because these enzymes play fundamental roles in steroid hormone action they can be considered to be drug targets for a variety of steroid driven diseases, e.g. metabolic syndrome and obesity, inflammation, and hormone dependent malignancies of the endometrium, prostate and breast. This article will review how fundamental knowledge of these enzymes can be exploited in the development of isoform specific HSD inhibitors from both protein superfamilies. Article from the Special issue on Targeted Inhibitors.
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Affiliation(s)
- Trevor M Penning
- Center of Excellence in Environmental Toxicology, Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6084, USA.
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34
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Chen M, Drury JE, Penning TM. Substrate specificity and inhibitor analyses of human steroid 5β-reductase (AKR1D1). Steroids 2011; 76:484-90. [PMID: 21255593 PMCID: PMC3056882 DOI: 10.1016/j.steroids.2011.01.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 11/29/2010] [Accepted: 01/13/2011] [Indexed: 12/31/2022]
Abstract
Human steroid 5β-reductase (aldo-keto reductase 1D1) catalyzes the stereospecific NADPH-dependent reduction of the C4-C5 double bond of Δ(4)-ketosteroids to yield an A/B cis-ring junction. This cis-configuration is crucial for bile acid biosynthesis and plays important roles in steroid metabolism. The biochemical properties of the enzyme have not been thoroughly studied and conflicting data have been reported, partially due to the lack of highly homogeneous protein. In the present study, we systematically determined the substrate specificity of homogeneous human recombinant AKR1D1 using C18, C19, C21, and C27 Δ(4)-ketosteroids and assessed the pH-rate dependence of the enzyme. Our results show that AKR1D1 proficiently reduced all the steroids tested at physiological pH, indicating AKR1D1 is the only enzyme necessary for all the 5β-steroid metabolites present in humans. Substrate inhibition was observed with C18 to C21 steroids provided that the C11 position was unsubstituted. This structure activity relationship can be explained by the existence of a small alternative substrate binding pocket revealed by the AKR1D1 crystal structure. Non-steroidal anti-inflammatory drugs which are potent inhibitors of the related AKR1C enzymes do not inhibit AKR1D1. By contrast chenodeoxycholate and ursodeoxycholate were found to be potent non-competitive inhibitors suggesting that bile-acids may regulate their own synthesis at the level of AKR1D1 inhibition.
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Affiliation(s)
- Mo Chen
- Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104-6084, USA
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35
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Mohler JL, Titus MA, Bai S, Kennerley BJ, Lih FB, Tomer KB, Wilson EM. Activation of the androgen receptor by intratumoral bioconversion of androstanediol to dihydrotestosterone in prostate cancer. Cancer Res 2011; 71:1486-96. [PMID: 21303972 DOI: 10.1158/0008-5472.can-10-1343] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The androgen receptor (AR) mediates the growth of benign and malignant prostate in response to dihydrotestosterone (DHT). In patients undergoing androgen deprivation therapy for prostate cancer, AR drives prostate cancer growth despite low circulating levels of testicular androgen and normal levels of adrenal androgen. In this report, we demonstrate the extent of AR transactivation in the presence of 5α-androstane-3α,17β-diol (androstanediol) in prostate-derived cell lines parallels the bioconversion of androstanediol to DHT. AR transactivation in the presence of androstanediol in prostate cancer cell lines correlated mainly with mRNA and protein levels of 17β-hydroxysteroid dehydrogenase 6 (17β-HSD6), one of several enzymes required for the interconversion of androstanediol to DHT and the inactive metabolite androsterone. Levels of retinol dehydrogenase 5, and dehydrogenase/reductase short-chain dehydrogenase/reductase family member 9, which also convert androstanediol to DHT, were lower than 17β-HSD6 in prostate-derived cell lines and higher in the castration-recurrent human prostate cancer xenograft. Measurements of tissue androstanediol using mass spectrometry demonstrated androstanediol metabolism to DHT and androsterone. Administration of androstanediol dipropionate to castration-recurrent CWR22R tumor-bearing athymic castrated male mice produced a 28-fold increase in intratumoral DHT levels. AR transactivation in prostate cancer cells in the presence of androstanediol resulted from the cell-specific conversion of androstanediol to DHT, and androstanediol increased LAPC-4 cell growth. The ability to convert androstanediol to DHT provides a mechanism for optimal utilization of androgen precursors and catabolites for DHT synthesis.
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Affiliation(s)
- James L Mohler
- Department of Urology, Roswell Park Cancer Institute, Buffalo, New York, USA
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Miller WL, Auchus RJ. The molecular biology, biochemistry, and physiology of human steroidogenesis and its disorders. Endocr Rev 2011; 32:81-151. [PMID: 21051590 PMCID: PMC3365799 DOI: 10.1210/er.2010-0013] [Citation(s) in RCA: 1432] [Impact Index Per Article: 110.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Accepted: 08/20/2010] [Indexed: 02/08/2023]
Abstract
Steroidogenesis entails processes by which cholesterol is converted to biologically active steroid hormones. Whereas most endocrine texts discuss adrenal, ovarian, testicular, placental, and other steroidogenic processes in a gland-specific fashion, steroidogenesis is better understood as a single process that is repeated in each gland with cell-type-specific variations on a single theme. Thus, understanding steroidogenesis is rooted in an understanding of the biochemistry of the various steroidogenic enzymes and cofactors and the genes that encode them. The first and rate-limiting step in steroidogenesis is the conversion of cholesterol to pregnenolone by a single enzyme, P450scc (CYP11A1), but this enzymatically complex step is subject to multiple regulatory mechanisms, yielding finely tuned quantitative regulation. Qualitative regulation determining the type of steroid to be produced is mediated by many enzymes and cofactors. Steroidogenic enzymes fall into two groups: cytochrome P450 enzymes and hydroxysteroid dehydrogenases. A cytochrome P450 may be either type 1 (in mitochondria) or type 2 (in endoplasmic reticulum), and a hydroxysteroid dehydrogenase may belong to either the aldo-keto reductase or short-chain dehydrogenase/reductase families. The activities of these enzymes are modulated by posttranslational modifications and by cofactors, especially electron-donating redox partners. The elucidation of the precise roles of these various enzymes and cofactors has been greatly facilitated by identifying the genetic bases of rare disorders of steroidogenesis. Some enzymes not principally involved in steroidogenesis may also catalyze extraglandular steroidogenesis, modulating the phenotype expected to result from some mutations. Understanding steroidogenesis is of fundamental importance to understanding disorders of sexual differentiation, reproduction, fertility, hypertension, obesity, and physiological homeostasis.
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Affiliation(s)
- Walter L Miller
- Distinguished Professor of Pediatrics, University of California San Francisco, San Francisco, California 94143-0978, USA.
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Campbell E, Wheeldon IR, Banta S. Broadening the cofactor specificity of a thermostable alcohol dehydrogenase using rational protein design introduces novel kinetic transient behavior. Biotechnol Bioeng 2011; 107:763-74. [PMID: 20632378 DOI: 10.1002/bit.22869] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cofactor specificity in the aldo-keto reductase (AKR) superfamily has been well studied, and several groups have reported the rational alteration of cofactor specificity in these enzymes. Although most efforts have focused on mesostable AKRs, several putative AKRs have recently been identified from hyperthermophiles. The few that have been characterized exhibit a strong preference for NAD(H) as a cofactor, in contrast to the NADP(H) preference of the mesophilic AKRs. Using the design rules elucidated from mesostable AKRs, we introduced two site-directed mutations in the cofactor binding pocket to investigate cofactor specificity in a thermostable AKR, AdhD, which is an alcohol dehydrogenase from Pyrococcus furiosus. The resulting double mutant exhibited significantly improved activity and broadened cofactor specificity as compared to the wild-type. Results of previous pre-steady-state kinetic experiments suggest that the high affinity of the mesostable AKRs for NADP(H) stems from a conformational change upon cofactor binding which is mediated by interactions between a canonical arginine and the 2'-phosphate of the cofactor. Pre-steady-state kinetics with AdhD and the new mutants show a rich conformational behavior that is independent of the canonical arginine or the 2'-phosphate. Additionally, experiments with the highly active double mutant using NADPH as a cofactor demonstrate an unprecedented transient behavior where the binding mechanism appears to be dependent on cofactor concentration. These results suggest that the structural features involved in cofactor specificity in the AKRs are conserved within the superfamily, but the dynamic interactions of the enzyme with cofactors are unexpectedly complex.
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Affiliation(s)
- Elliot Campbell
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, New York, New York 10027, USA
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38
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El-Kabbani O, Scammells PJ, Day T, Dhagat U, Endo S, Matsunaga T, Soda M, Hara A. Structure-based optimization and biological evaluation of human 20α-hydroxysteroid dehydrogenase (AKR1C1) salicylic acid-based inhibitors. Eur J Med Chem 2010; 45:5309-17. [PMID: 20850205 DOI: 10.1016/j.ejmech.2010.08.052] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 08/08/2010] [Accepted: 08/24/2010] [Indexed: 10/19/2022]
Abstract
The tertiary structure of the Leu308Val mutant of human 20α-hydroxysteroid dehydrogenase (AKR1C1) in complex with the inhibitor 3,5-dichlorosalicylic acid (DCL) has been determined. Structures and kinetic properties of the wild-type and mutant enzymes indicate that Leu308 is a selectivity determinant for inhibitor binding. The Leu308Val mutation resulted in 13-fold and 3-fold reductions in the inhibitory potencies of DCL and 3-bromo-5-phenylsalicylic acid (BPSA), respectively. The replacement of Leu308 with an alanine resulted in 473-fold and 27-fold reductions in the potencies for DCL and BPSA, respectively. In our attempts to optimize inhibitor potency and selectivity we synthesized 5-substituted 3-chlorosalicylic acid derivatives, of which the most potent compound, 3-chloro-5-phenylsalicylic acid (K(i) = 0.86 nM), was 24-fold more selective for AKR1C1 relative to the structurally similar 3α-hydroxysteroid dehydrogenase (AKR1C2). Furthermore, the compound inhibited the metabolism of progesterone in AKR1C1-overexpressed cells with an IC(50) value equal to 100 nM.
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Affiliation(s)
- Ossama El-Kabbani
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia.
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39
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Negri M, Recanatini M, Hartmann RW. Insights in 17beta-HSD1 enzyme kinetics and ligand binding by dynamic motion investigation. PLoS One 2010; 5:e12026. [PMID: 20706575 PMCID: PMC2919385 DOI: 10.1371/journal.pone.0012026] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Accepted: 07/06/2010] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Bisubstrate enzymes, such as 17beta-hydroxysteroid dehydrogenase type 1 (17beta-HSD1), exist in solution as an ensemble of conformations. 17beta-HSD1 catalyzes the last step of the biosynthesis of estradiol and, thus, it is a potentially attractive target for breast cancer treatment. METHODOLOGY/PRINCIPAL FINDINGS To elucidate the conformational transitions of its catalytic cycle, a structural analysis of all available crystal structures was performed and representative conformations were assigned to each step of the putative kinetic mechanism. To cover most of the conformational space, all-atom molecular dynamic simulations were performed using the four crystallographic structures best describing apoform, opened, occluded and closed state of 17beta-HSD1 as starting structures. With three of them, binary and ternary complexes were built with NADPH and NADPH-estrone, respectively, while two were investigated as apoform. Free energy calculations were performed in order to judge more accurately which of the MD complexes describes a specific kinetic step. CONCLUSIONS/SIGNIFICANCE Remarkably, the analysis of the eight long range trajectories resulting from this multi-trajectory/-complex approach revealed an essential role played by the backbone and side chain motions, especially of the betaF alphaG'-loop, in cofactor and substrate binding. Thus, a selected-fit mechanism is suggested for 17beta-HSD1, where ligand-binding induced concerted motions of the FG-segment and the C-terminal part guide the enzyme along its preferred catalytic pathway. Overall, we could assign different enzyme conformations to the five steps of the random bi-bi kinetic cycle of 17beta-HSD1 and we could postulate a preferred pathway for it. This study lays the basis for more-targeted biochemical studies on 17beta-HSD1, as well as for the design of specific inhibitors of this enzyme. Moreover, it provides a useful guideline for other enzymes, also characterized by a rigid core and a flexible region directing their catalysis.
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Affiliation(s)
- Matthias Negri
- Pharmaceutical and Medicinal Chemistry, Saarland University, Saarbrücken, Germany
- Helmholtz Institute for Pharmaceutical Research Saarland, Saarbrücken, Germany
| | - Maurizio Recanatini
- Department of Pharmaceutical Sciences, University of Bologna, Bologna, Italy
| | - Rolf W. Hartmann
- Pharmaceutical and Medicinal Chemistry, Saarland University, Saarbrücken, Germany
- Helmholtz Institute for Pharmaceutical Research Saarland, Saarbrücken, Germany
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Dhagat U, Endo S, Soda M, Hara A, El-Kabbani O. Factorizing the role of a critical leucine residue in the binding of substrate to human 20alpha-hydroxysteroid dehydrogenase (AKR1C1): molecular modeling and kinetic studies of the Leu308Val mutant enzyme. Bioorg Med Chem Lett 2010; 20:5274-6. [PMID: 20656485 DOI: 10.1016/j.bmcl.2010.06.137] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 06/28/2010] [Indexed: 11/15/2022]
Abstract
A comparison of the structures and kinetic properties of human 20alpha-hydroxysteroid dehydrogenase (AKR1C1) and its mutant enzymes (Leu308Val and Leu308Ala) indicates that Leu308 is a selectivity determinant for substrate binding. While the Leu308Val mutation improved the catalytic efficiency (k(cat)/K(m)) of AKR1C1 towards the two substrates 5alpha-pregnane-3alpha,20alpha-diol (PregA) and 5beta-pregnan-3alpha-ol-20-one (PregB), the Leu308Ala mutation rendered the enzyme inactive. In the docked model of PregA the conformation of the steroid molecule was similar to that of 20alpha-hydroxyprogesterone in the crystal structure of the AKR1C1 complex where the steroid did not interact with the catalytic residues Tyr55 and His117. In the case of PregB the steroid interacted with the catalytic residue His117 and formed close contacts with Leu308, suggesting that the binding mechanism of 3alpha-hydroxysteroids in the active site of AKR1C1 is different from that of 20alpha-hydroxysteroids.
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Affiliation(s)
- Urmi Dhagat
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia
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41
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Sherbet DP, Guryev OL, Papari-Zareei M, Mizrachi D, Rambally S, Akbar S, Auchus RJ. Biochemical factors governing the steady-state estrone/estradiol ratios catalyzed by human 17beta-hydroxysteroid dehydrogenases types 1 and 2 in HEK-293 cells. Endocrinology 2009; 150:4154-62. [PMID: 19556422 PMCID: PMC2736091 DOI: 10.1210/en.2008-1817] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Human 17beta-hydroxysteroid dehydrogenase types 1 and 2 (17betaHSD1 and 17betaHSD2) regulate estrogen potency by catalyzing the interconversion of estrone (E1) and estradiol (E2) using nicotinamide adenine dinucleotide (phosphate) cofactors NAD(P)(H). In intact cells, 17betaHSD1 and 17betaHSD2 establish pseudo-equilibria favoring E1 reduction or E2 oxidation, respectively. The vulnerability of these equilibrium steroid distributions to mutations and to altered intracellular cofactor abundance and redox state, however, is not known. We demonstrate that the equilibrium E2/E1 ratio achieved by 17betaHSD1 in intact HEK-293 cell lines is progressively reduced from 94:6 to 10:90 after mutagenesis of R38, which interacts with the 2'-phosphate of NADP(H), and by glucose deprivation, which lowers the NADPH/NADP(+) ratio. The shift to E2 oxidation parallels changes in apparent K(m) values for purified 17betaHSD1 proteins to favor NAD(H) over NADP(H). In contrast, mutagenesis of E116 (corresponding to R38 in 17betaHSD1) and changes in intracellular cofactor ratios do not alter the greater than 90:10 E1/E2 ratio catalyzed by 17betaHSD2, and these mutations lower the apparent K(m) of recombinant 17betaHSD2 for NADP(H) only less than 3-fold. We conclude that the equilibrium E1/E2 ratio maintained by human 17betaHSD1 in intact cells is governed by NADPH saturation, which is strongly dependent on both R38 and high intracellular NADPH/NADP(+) ratios. In contrast, the preference of 17betaHSD2 for E2 oxidation strongly resists alteration by genetic and metabolic manipulations. These findings suggest that additional structural features, beyond the lack of a specific arginine residue, disfavor NADPH binding and thus support E2 oxidation by 17betaHSD2 in intact cells.
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Affiliation(s)
- Daniel P Sherbet
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8857, USA
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42
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Simpson PJ, Tantitadapitak C, Reed AM, Mather OC, Bunce CM, White SA, Ride JP. Characterization of two novel aldo-keto reductases from Arabidopsis: expression patterns, broad substrate specificity, and an open active-site structure suggest a role in toxicant metabolism following stress. J Mol Biol 2009; 392:465-80. [PMID: 19616008 DOI: 10.1016/j.jmb.2009.07.023] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 06/26/2009] [Accepted: 07/09/2009] [Indexed: 11/17/2022]
Abstract
Aldo-keto reductases (AKRs) are widely distributed in nature and play numerous roles in the metabolism of steroids, sugars, and other carbonyls. They have also frequently been implicated in the metabolism of exogenous and endogenous toxicants, including those stimulated by stress. Although the Arabidopsis genome includes at least 21 genes with the AKR signature, very little is known of their functions. In this study, we have screened the Arabidopsis thaliana genomic sequence for genes with significant homology to members of the mammalian AKR1 family and identified four homologues for further study. Following alignment of the predicted protein sequences with representatives from the AKR superfamily, the proteins were ascribed not to the AKR1 family but to the AKR4C subfamily, with the individual designations of AKR4C8, AKR4C9, AKR4C10, and AKR4C11. Expression of two of the genes, AKR4C8 and AKR4C9, has been shown to be coordinately regulated and markedly induced by various forms of stress. The genes have been overexpressed in bacteria, and recombinant proteins have been purified and crystallized. Both enzymes display NADPH-dependent reduction of carbonyl compounds, typical of the superfamily, but will accept a very wide range of substrates, reducing a range of steroids, sugars, and aliphatic and aromatic aldehydes/ketones, although there are distinct differences between the two enzymes. We have obtained high-resolution crystal structures of AKR4C8 (1.4 A) and AKR4C9 (1.25 A) in ternary complexes with NADP(+) and acetate. Three extended loops, present in all AKRs and responsible for defining the cofactor- and substrate-binding sites, are shorter in the 4C subfamily compared to other AKRs. Consequently, the crystal structures reveal open and accommodative substrate-binding sites, which correlates with their broad substrate specificity. It is suggested that the primary role of these enzymes may be to detoxify a range of toxic aldehydes and ketones produced during stress, although the precise nature of the principal natural substrates remains to be determined.
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Affiliation(s)
- Paul J Simpson
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, UK
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43
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Mizrachi D, Auchus RJ. Androgens, estrogens, and hydroxysteroid dehydrogenases. Mol Cell Endocrinol 2009; 301:37-42. [PMID: 18824065 DOI: 10.1016/j.mce.2008.08.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 08/23/2008] [Accepted: 08/25/2008] [Indexed: 11/17/2022]
Abstract
The task of regulating both production and activity of potent androgens and estrogens in human physiology is largely relegated to the hydroxysteroid dehydrogenases (HSDs). Although over two dozen enzymes with HSD activities have been described, we only understand the physiology of a small number, and for only one enzyme has the function been unequivocally determined by the study of human mutations. The physiology of the HSDs derive from their enzymatic activities, which in turn derive from their respective structures. In general, pairs of enzymes that drive steroid flux in opposite directions are found, and we have been studying the biochemical principles which enable dichotomous enzymes to perform their specific functions. In general, these directional preferences in intact cells are governed by relative affinities for nicotinamide adenine dinucleotide (phosphate) cofactors [NAD(P)(H)] and concentration gradients of these cofactors in subcellular compartments. For the reductive HSDs human 17betaHSD type 1 and rat AKR1C9, we can attenuate or reverse the directional preference in intact cells by site-directed mutagenesis in the cofactor-binding domain or by glucose deprivation, but the magnitude of such changes vary with the different enzymes.
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Affiliation(s)
- Dario Mizrachi
- Divisions of Endocrinology & Metabolism, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-8857, USA
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44
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Jin Y, Duan L, Lee SH, Kloosterboer HJ, Blair IA, Penning TM. Human cytosolic hydroxysteroid dehydrogenases of the aldo-ketoreductase superfamily catalyze reduction of conjugated steroids: implications for phase I and phase II steroid hormone metabolism. J Biol Chem 2009; 284:10013-22. [PMID: 19218247 DOI: 10.1074/jbc.m809465200] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Aldo-ketoreductase 1C (AKR1C) enzymes catalyze the NADPH-dependent reduction of ketosteroids to hydroxysteroids. They are Phase I metabolizing enzymes for natural and synthetic steroid hormones. They convert 5alpha-dihydrotestosterone (Dht, potent androgen) to 3alpha/beta-androstanediols (inactive androgens) and the prodrug tibolone (Tib) to estrogenic 3alpha/beta-hydroxytibolones. Herein we demonstrate for the first time that human AKR1C enzymes (AKR1C1-4) are able to reduce conjugated steroids such as Dht-17beta-glucuronide (DhtG), Dht-17beta-sulfate (DhtS), and Tib-17beta-sulfate (TibS). Product identities were characterized by liquid chromatography-mass spectrometry, and kinetic parameters of the reactions were determined. The product profile of the reduction of each steroid conjugate by the individual AKR1C isoform was similar to that of the corresponding free steroid except for the reduction of DhtG catalyzed by AKR1C2, where a complete inversion in stereochemical preference to 3beta-reduction (with DhtG) from 3alpha-reduction (with Dht and DhtS) was observed. The catalytic efficiency of 3-keto reduction was modestly affected by the presence of a 17-sulfate group but severely impaired by the presence of a 17-glucuronide group for AKR1C1-3 isoforms. AKR1C4, however, showed superior catalytic efficiencies versus the other isoforms, and those were unaffected by steroid conjugation. Our findings provide evidence for alternative pathways of steroid metabolism where the phase I reaction (reduction) occurs after the phase II reaction (conjugation). Specifically, it is indicated that Dht is metabolized to its metabolite 3alpha-androstanediol-17-glucuronide via the previously unrecognized "conjugation pathway" involving the sequential reactions of UGT2B17 and AKR1C4 in liver but via the conventional "reduction pathway" involving the sequential reactions of AKR1C2 and UGT2B15/17 in prostate.
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Affiliation(s)
- Yi Jin
- Centers of Excellence in Environmental Toxicology and Cancer Pharmacology, Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6084, USA
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Abstract
Prostate and breast cancer are hormone-dependent malignancies of the aging male and female and require the local production of androgens and estrogens to stimulate cell proliferation. Aldo-keto reductases (AKR) play key roles in this process. In the prostate, AKR1C3 (type 5 17beta-HSD) reduces Delta(4)-androstene-3,17-dione to yield testosterone while AKR1C2 (type 3 3alpha-HSD) eliminates 5alpha-dihydrotestosterone (5alpha-DHT), and AKR1C1 forms 3beta-androstanediol (a ligand for ERbeta). In the breast, AKR1C3 forms testosterone, which is converted to 17beta-estradiol by aromatase or reduces estrone to 17beta-estradiol directly. AKR1C3 also acts as a prostaglandin (PG) F synthase and forms PGF(2alpha) and 11beta-PGF(2alpha), which stimulate the FP receptor and prevent the activation of PPARgamma by PGJ(2) ligands. This proproliferative signaling may stimulate the growth of hormone-dependent and -independent prostate and breast cancer.
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Affiliation(s)
- Trevor M Penning
- Center of Excellence in Environmental Toxicology, Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6084, USA.
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46
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Faucher F, Cantin L, Luu-The V, Labrie F, Breton R. Crystal structures of human Delta4-3-ketosteroid 5beta-reductase (AKR1D1) reveal the presence of an alternative binding site responsible for substrate inhibition. Biochemistry 2009; 47:13537-46. [PMID: 19075558 DOI: 10.1021/bi801276h] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The 5beta-reductases (AKR1D1-3) are unique enzymes able to catalyze efficiently and in a stereospecific manner the 5beta-reduction of the C4-C5 double bond found in Delta4-3-ketosteroids, including steroid hormones and bile acids precursors such as 7alpha-hydroxy-4-cholesten-3-one and 7alpha,12alpha-dihydroxy-4-cholesten-3-one. In order to elucidate the binding mode and substrate specificity in detail, biochemical and structural studies on human 5beta-reductase (h5beta-red; AKR1D1) have been recently undertaken. The crystal structure of a h5beta-red binary complex provides a complete picture of the NADPH-enzyme interactions involving the flexible loop B, which contributes to the maintenance of the cofactor in its binding site by acting as a "safety belt". Structural comparison with binary complexes of AKR1C enzymes, specifically the human type 3 3alpha-hydroxysteroid dehydrogenase (AKR1C2) and the mouse 17alpha-hydroxysteroid dehydrogenase (AKR1C21), also revealed particularities in loop B positioning that make the steroid-binding cavity of h5beta-red substantially larger than those of the two other enzymes. Kinetic characterization of the purified recombinant h5beta-red has shown that this enzyme exerts a strong activity toward progesterone (Prog) and androstenedione (Delta4) but is rapidly inhibited by these substrates once their concentrations reach 2-times their K(m) value. A crystal structure of the h5beta-red in ternary complex with NADPH and Delta4 has revealed that the large steroid-binding site of this enzyme also contains a subsite in which the Delta4 molecule is found. When bound in this subsite, Delta4 completely impedes the passage of another substrate molecule toward the catalytic site. The importance of this alternative binding site for the inhibition of h5beta-red was finally proven by site-directed mutagenesis, which demonstrated that the replacement of one of the residues delineating this site (Val(309)) by a phenylalanine completely abolishes the substrate inhibition. The results of this report provide structural insights into the substrate inhibition of h5beta-red by C19- and C21-steroids.
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Affiliation(s)
- Frédérick Faucher
- Oncology and Molecular Endocrinology Research Center, Laval University Medical Center (CHUL) and Laval University, Laval, Quebec (QC) G1V 4G2, Canada
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Ruiz FX, Gallego O, Ardèvol A, Moro A, Domínguez M, Alvarez S, Alvarez R, de Lera AR, Rovira C, Fita I, Parés X, Farrés J. Aldo-keto reductases from the AKR1B subfamily: retinoid specificity and control of cellular retinoic acid levels. Chem Biol Interact 2008; 178:171-7. [PMID: 19014918 DOI: 10.1016/j.cbi.2008.10.027] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 10/16/2008] [Accepted: 10/16/2008] [Indexed: 01/28/2023]
Abstract
NADP(H)-dependent cytosolic aldo-keto reductases (AKRs) have been added to the group of enzymes which contribute to oxidoreductive conversions of retinoids. Recently, we found that two members from the AKR1B subfamily (AKR1B1 and AKRB10) were active in the reduction of all-trans- and 9-cis-retinaldehyde, with K(m) values in the micromolar range, but with very different k(cat) values. With all-trans-retinaldehyde, AKR1B10 shows a much higher k(cat) value than AKR1B1 (18 min(-1)vs. 0.37 min(-1)) and a catalytic efficiency comparable to that of the best retinaldehyde reductases. Structural, molecular dynamics and site-directed mutagenesis studies on AKR1B1 and AKR1B10 point that subtle differences at the entrance of their retinoid-binding site, especially at position 125, are determinant for the all-trans-retinaldehyde specificity of AKR1B10. Substitutions in the retinoid cyclohexene ring, analyzed here further, also influence such specificity. Overall it is suggested that the rate-limiting step in the reaction mechanism with retinaldehyde differs between AKR1B1 and AKR1B10. In addition, we demonstrate here that enzymatic activity of AKR1B1 and AKR1B10 lowers all-trans- and 9-cis-retinoic acid-dependent trans-activation in living cells, indicating that both enzymes may contribute to pre-receptor regulation of retinoic acid and retinoid X nuclear receptors. This result supports that overexpression of AKR1B10 in cancer (an updated review on this topic is included) may contribute to dedifferentiation and tumor development.
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Affiliation(s)
- F Xavier Ruiz
- Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
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