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Lv L, Li Q, Wang K, Zhao J, Deng K, Zhang R, Chen Z, Khan IA, Gui C, Feng S, Yang S, Liu Y, Xu Q. Discovery of a New Anti-Inflammatory Agent from Anemoside B4 Derivatives and Its Therapeutic Effect on Colitis by Targeting Pyruvate Carboxylase. J Med Chem 2024; 67:7385-7405. [PMID: 38687956 DOI: 10.1021/acs.jmedchem.4c00222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Anemoside B4 (AB4), a triterpenoidal saponin from Pulsatilla chinensis, shows significant anti-inflammatory activity, and may be used for treating inflammatory bowel disease (IBD). Nevertheless, its application is limited due to its high molecular weight and pronounced water solubility. To discover new effective agents for treating IBD, we synthesized 28 AB4 derivatives and evaluated their cytotoxic and anti-inflammatory activities in vitro. Among them, A3-6 exhibited significantly superior anti-inflammatory activity compared to AB4. It showed a significant improvement in the symptoms of DSS-induced colitis in mice, with a notably lower oral effective dose compared to AB4. Furthermore, we discovered that A3-6 bound with pyruvate carboxylase (PC), then inhibited PC activity, reprogramming macrophage function, and alleviated colitis. These findings indicate that A3-6 is a promising therapeutic candidate for colitis, and PC may be a potential new target for treating colitis.
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Affiliation(s)
- Lijuan Lv
- College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Qiurong Li
- College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Kexin Wang
- College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Jianping Zhao
- National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Kejun Deng
- School of Life Science and Technology, Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054, China
| | - Ran Zhang
- College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Zhong Chen
- College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Ikhlas A Khan
- National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Chunshan Gui
- College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Suxiang Feng
- Academy of Chinese Medicine Sciences, Henan University of Chinese Medicine, Zhengzhou, Henan 450018, China
| | - Shilin Yang
- College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Yanli Liu
- College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Qiongming Xu
- College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
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Liang QH, Li QR, Chen Z, Lv LJ, Lin Y, Jiang HL, Wang KX, Xiao MY, Kang NX, Tu PF, Ji SL, Deng KJ, Gao HW, Zhang L, Li K, Ge F, Xu GQ, Yang SL, Liu YL, Xu QM. Anemoside B4, a new pyruvate carboxylase inhibitor, alleviates colitis by reprogramming macrophage function. Inflamm Res 2024; 73:345-362. [PMID: 38157008 DOI: 10.1007/s00011-023-01840-x] [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: 08/08/2023] [Revised: 12/08/2023] [Accepted: 12/14/2023] [Indexed: 01/03/2024] Open
Abstract
OBJECTIVES Colitis is a global disease usually accompanied by intestinal epithelial damage and intestinal inflammation, and an increasing number of studies have found natural products to be highly effective in treating colitis. Anemoside B4 (AB4), an abundant saponin isolated from Pulsatilla chinensis (Bunge), which was found to have strong anti-inflammatory activity. However, the exact molecular mechanisms and direct targets of AB4 in the treatment of colitis remain to be discovered. METHODS The anti-inflammatory activities of AB4 were verified in LPS-induced cell models and 2, 4, 6-trinitrobenzene sulfonic (TNBS) or dextran sulfate sodium (DSS)-induced colitis mice and rat models. The molecular target of AB4 was identified by affinity chromatography analysis using chemical probes derived from AB4. Experiments including proteomics, molecular docking, biotin pull-down, surface plasmon resonance (SPR), and cellular thermal shift assay (CETSA) were used to confirm the binding of AB4 to its molecular target. Overexpression of pyruvate carboxylase (PC) and PC agonist were used to study the effects of PC on the anti-inflammatory and metabolic regulation of AB4 in vitro and in vivo. RESULTS AB4 not only significantly inhibited LPS-induced NF-κB activation and increased ROS levels in THP-1 cells, but also suppressed TNBS/DSS-induced colonic inflammation in mice and rats. The molecular target of AB4 was identified as PC, a key enzyme related to fatty acid, amino acid and tricarboxylic acid (TCA) cycle. We next demonstrated that AB4 specifically bound to the His879 site of PC and altered the protein's spatial conformation, thereby affecting the enzymatic activity of PC. LPS activated NF-κB pathway and increased PC activity, which caused metabolic reprogramming, while AB4 reversed this phenomenon by inhibiting the PC activity. In vivo studies showed that diisopropylamine dichloroacetate (DADA), a PC agonist, eliminated the therapeutic effects of AB4 by changing the metabolic rearrangement of intestinal tissues in colitis mice. CONCLUSION We identified PC as a direct cellular target of AB4 in the modulation of inflammation, especially colitis. Moreover, PC/pyruvate metabolism/NF-κB is crucial for LPS-driven inflammation and oxidative stress. These findings shed more light on the possibilities of PC as a potential new target for treating colitis.
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Affiliation(s)
- Qing-Hua Liang
- College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
| | - Qiu-Rong Li
- College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
| | - Zhong Chen
- College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
| | - Li-Juan Lv
- College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
| | - Yu Lin
- College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
| | - Hong-Lv Jiang
- College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
| | - Ke-Xin Wang
- College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
| | - Ming-Yue Xiao
- College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
| | - Nai-Xin Kang
- College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
| | - Peng-Fei Tu
- State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100191, China
| | - Shi-Liang Ji
- Department of Pharmacy, Suzhou Science & Technology Town Hospital, Gusu School, Nanjing Medical University, Suzhou, 215163, Jiangsu, China
| | - Ke-Jun Deng
- School of Life Science and Technology, Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu, 610054, Sichuan, China
| | - Hong-Wei Gao
- College of Pharmacy, Guangxi University of Chinese Medicine, Nanning, 530000, Guangxi, China
- Guangxi Xinhai Pharmaceutical Technology Co.,Ltd, , Liuzhou, 545025, Guangxi, China
| | - Li Zhang
- Instrumental Analysis Center, Shanghai JiaoTong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Kun Li
- Hai'an Traditional Chinese Medicine Hospital, Nantong, 226600, Jiangsu, China
| | - Fei Ge
- Hai'an Traditional Chinese Medicine Hospital, Nantong, 226600, Jiangsu, China
| | - Guo-Qiang Xu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Jiangsu Province Engineering Research Center of Precision Diagnostics and Therapeutics Development, Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Suzhou Key Laboratory of Drug Research for Prevention and Treatment of Hyperlipidemic Diseases, Soochow University, Suzhou, 215123, Jiangsu, China
| | - Shi-Lin Yang
- College of Pharmacy, Guangxi University of Chinese Medicine, Nanning, 530000, Guangxi, China
- Guangxi Xinhai Pharmaceutical Technology Co.,Ltd, , Liuzhou, 545025, Guangxi, China
| | - Yan-Li Liu
- College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China.
| | - Qiong-Ming Xu
- College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China.
- Guangxi Xinhai Pharmaceutical Technology Co.,Ltd, , Liuzhou, 545025, Guangxi, China.
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Burkett DJ, Wyatt BN, Mews M, Bautista A, Engel R, Dockendorff C, Donaldson WA, St Maurice M. Evaluation of α-hydroxycinnamic acids as pyruvate carboxylase inhibitors. Bioorg Med Chem 2019; 27:4041-4047. [PMID: 31351848 DOI: 10.1016/j.bmc.2019.07.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Revised: 07/10/2019] [Accepted: 07/14/2019] [Indexed: 10/26/2022]
Abstract
Through a structure-based drug design project (SBDD), potent small molecule inhibitors of pyruvate carboxylase (PC) have been discovered. A series of α-keto acids (7) and α-hydroxycinnamic acids (8) were prepared and evaluated for inhibition of PC in two assays. The two most potent inhibitors were 3,3'-(1,4-phenylene)bis[2-hydroxy-2-propenoic acid] (8u) and 2-hydroxy-3-(quinoline-2-yl)propenoic acid (8v) with IC50 values of 3.0 ± 1.0 μM and 4.3 ± 1.5 μM respectively. Compound 8v is a competitive inhibitor with respect to pyruvate (Ki = 0.74 μM) and a mixed-type inhibitor with respect to ATP, indicating that it targets the unique carboxyltransferase (CT) domain of PC. Furthermore, compound 8v does not significantly inhibit human carbonic anhydrase II, matrix metalloproteinase-2, malate dehydrogenase or lactate dehydrogenase.
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Affiliation(s)
- Daniel J Burkett
- Department of Chemistry, Marquette University, P. O. Box 1881, Milwaukee, WI 53201-1881, USA
| | - Brittney N Wyatt
- Department of Biological Sciences, Marquette University, P. O. Box 1881, Milwaukee, WI 53201-1881, USA
| | - Mallory Mews
- Department of Biological Sciences, Marquette University, P. O. Box 1881, Milwaukee, WI 53201-1881, USA
| | - Anson Bautista
- Department of Chemistry, Marquette University, P. O. Box 1881, Milwaukee, WI 53201-1881, USA
| | - Ryan Engel
- Department of Chemistry, Marquette University, P. O. Box 1881, Milwaukee, WI 53201-1881, USA
| | - Chris Dockendorff
- Department of Chemistry, Marquette University, P. O. Box 1881, Milwaukee, WI 53201-1881, USA
| | - William A Donaldson
- Department of Chemistry, Marquette University, P. O. Box 1881, Milwaukee, WI 53201-1881, USA.
| | - Martin St Maurice
- Department of Biological Sciences, Marquette University, P. O. Box 1881, Milwaukee, WI 53201-1881, USA.
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Sheng X, Hou Q, Liu Y. Computational evidence for the importance of lysine carboxylation in the reaction catalyzed by carboxyl transferase domain of pyruvate carboxylase: a QM/MM study. Theor Chem Acc 2019. [DOI: 10.1007/s00214-018-2408-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Liu Y, Budelier MM, Stine K, St Maurice M. Allosteric regulation alters carrier domain translocation in pyruvate carboxylase. Nat Commun 2018; 9:1384. [PMID: 29643369 PMCID: PMC5895798 DOI: 10.1038/s41467-018-03814-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 03/14/2018] [Indexed: 11/28/2022] Open
Abstract
Pyruvate carboxylase (PC) catalyzes the ATP-dependent carboxylation of pyruvate to oxaloacetate. The reaction occurs in two separate catalytic domains, coupled by the long-range translocation of a biotinylated carrier domain (BCCP). Here, we use a series of hybrid PC enzymes to examine multiple BCCP translocation pathways in PC. These studies reveal that the BCCP domain of PC adopts a wide range of translocation pathways during catalysis. Furthermore, the allosteric activator, acetyl CoA, promotes one specific intermolecular carrier domain translocation pathway. These results provide a basis for the ordered thermodynamic state and the enhanced carboxyl group transfer efficiency in the presence of acetyl CoA, and reveal that the allosteric effector regulates enzyme activity by altering carrier domain movement. Given the similarities with enzymes involved in the modular synthesis of natural products, the allosteric regulation of carrier domain movements in PC is likely to be broadly applicable to multiple important enzyme systems. Carrier domain enzymes accomplish catalysis by physically transporting intermediates long distances between remote active sites. Here the authors describe a wide range of catalytically productive translocation events during catalysis by pyruvate carboxylase and suggest a basis for its allosteric activation.
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Affiliation(s)
- Yumeng Liu
- Department of Biological Sciences, Marquette University, Milwaukee, WI, 53201, USA
| | - Melissa M Budelier
- Department of Biological Sciences, Marquette University, Milwaukee, WI, 53201, USA
| | - Katelyn Stine
- Department of Biological Sciences, Marquette University, Milwaukee, WI, 53201, USA
| | - Martin St Maurice
- Department of Biological Sciences, Marquette University, Milwaukee, WI, 53201, USA.
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Striking Diversity in Holoenzyme Architecture and Extensive Conformational Variability in Biotin-Dependent Carboxylases. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2017; 109:161-194. [PMID: 28683917 DOI: 10.1016/bs.apcsb.2017.04.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Biotin-dependent carboxylases are widely distributed in nature and have central roles in the metabolism of fatty acids, amino acids, carbohydrates, and other compounds. The last decade has seen the accumulation of structural information on most of these large holoenzymes, including the 500-kDa dimeric yeast acetyl-CoA carboxylase, the 750-kDa α6β6 dodecameric bacterial propionyl-CoA carboxylase, 3-methylcrotonyl-CoA carboxylase, and geranyl-CoA carboxylase, the 720-kDa hexameric bacterial long-chain acyl-CoA carboxylase, the 500-kDa tetrameric bacterial single-chain pyruvate carboxylase, the 370-kDa α2β4 bacterial two-subunit pyruvate carboxylase, and the 130-kDa monomeric eukaryotic urea carboxylase. A common theme that has emerged from these studies is the dramatic structural flexibility of these holoenzymes despite their strong overall sequence conservation, evidenced both by the extensive diversity in the architectures of the holoenzymes and by the extensive conformational variability of their domains and subunits. This structural flexibility is crucial for the function and regulation of these enzymes and identifying compounds that can interfere with it represents an attractive approach for developing novel modulators and drugs. The extensive diversity observed in the structures so far and its biochemical and functional implications will be the focus of this review.
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Transcriptome analysis of Corynebacterium glutamicum in the process of recombinant protein expression in bioreactors. PLoS One 2017; 12:e0174824. [PMID: 28369109 PMCID: PMC5378358 DOI: 10.1371/journal.pone.0174824] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 03/15/2017] [Indexed: 02/07/2023] Open
Abstract
Corynebacterium glutamicum (C. glutamicum) is a favorable host cell for the production of recombinant proteins, such as important enzymes and pharmaceutical proteins, due to its excellent potential advantages. Herein, we sought to systematically explore the influence of recombinant protein expression on the transcription and metabolism of C. glutamicum. Two C. glutamicum strains, the wild-type strain and an engineered strain expressing enhanced green fluorescent protein (EGFP), were cultured in parallel in 5-L bioreactors to study the change in metabolism in the process of EGFP expression. The results revealed that EGFP expression had great effects on the growth and metabolism of C. glutamicum and contributed to metabolism-like anaerobic conditions as follows: glycolysis was enhanced, the TCA cycle was shunted, and Glu, Val, Met, lactate and acetate were accumulated to produce sufficient ATP for EGFP production and transfer. Many differentially expressed genes related to ribosomal protein, transcriptional regulators, and energy metabolism were found to be expressed in the presence of EGFP, laying the foundation for identifying genomic loci to change the flow of the host cell metabolism to improve the ability of expressing foreign proteins in C. glutamicum.
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Liu X, Yang S, Wang F, Dai X, Yang Y, Bai Z. RETRACTED ARTICLE: Comparative analysis of the Corynebacterium glutamicum transcriptome in response to changes in dissolved oxygen levels. ACTA ACUST UNITED AC 2017; 44:181-195. [DOI: 10.1007/s10295-016-1854-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 10/30/2016] [Indexed: 12/13/2022]
Abstract
Abstract
The dissolved oxygen (DO) level of a culture of Corynebacterium glutamicum (C. glutamicum) in a bioreactor has a significant impact on the cellular redox potential and the distribution of energy and metabolites. In this study, to gain a deeper understanding of the effects of DO on the metabolism of C. glutamicum, we sought to systematically explore the influence of different DO concentrations on genetic regulation and metabolism through transcriptomic analysis. The results revealed that after 20 h of fermentation, oxygen limitation enhanced the glucose metabolism, pyruvate metabolism and carbon overflow, and restricted NAD+ availability. A high oxygen supply enhanced the TCA cycle and reduced glyoxylate metabolism. Several key genes involved in response of C. glutamicum to different oxygen concentrations were examined, which provided suggestions for target site modifications in developing optimized oxygen supply strategies. These data provided new insights into the relationship between oxygen supply and metabolism of C. glutamicum.
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Affiliation(s)
- Xiuxia Liu
- grid.258151.a 0000000107081323 National Engineering Laboratory for Cereal Fermentation Technology Jiangnan University 214122 Wuxi China
- grid.258151.a 0000000107081323 The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi China
- grid.258151.a 0000000107081323 The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi China
| | - Sun Yang
- grid.258151.a 0000000107081323 National Engineering Laboratory for Cereal Fermentation Technology Jiangnan University 214122 Wuxi China
- grid.258151.a 0000000107081323 The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi China
- grid.258151.a 0000000107081323 The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi China
| | - Fen Wang
- grid.258151.a 0000000107081323 National Engineering Laboratory for Cereal Fermentation Technology Jiangnan University 214122 Wuxi China
- grid.258151.a 0000000107081323 The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi China
- grid.258151.a 0000000107081323 The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi China
| | - Xiaofeng Dai
- grid.258151.a 0000000107081323 National Engineering Laboratory for Cereal Fermentation Technology Jiangnan University 214122 Wuxi China
- grid.258151.a 0000000107081323 The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi China
- grid.258151.a 0000000107081323 The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi China
| | - Yankun Yang
- grid.258151.a 0000000107081323 National Engineering Laboratory for Cereal Fermentation Technology Jiangnan University 214122 Wuxi China
- grid.258151.a 0000000107081323 The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi China
- grid.258151.a 0000000107081323 The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi China
| | - Zhonghu Bai
- grid.258151.a 0000000107081323 National Engineering Laboratory for Cereal Fermentation Technology Jiangnan University 214122 Wuxi China
- grid.258151.a 0000000107081323 The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi China
- grid.258151.a 0000000107081323 The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi China
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9
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Abstract
Pyruvate carboxylase is a metabolic enzyme that fuels the tricarboxylic acid cycle with one of its intermediates and also participates in the first step of gluconeogenesis. This large enzyme is multifunctional, and each subunit contains two active sites that catalyze two consecutive reactions that lead to the carboxylation of pyruvate into oxaloacetate, and a binding site for acetyl-CoA, an allosteric regulator of the enzyme. Pyruvate carboxylase oligomers arrange in tetramers and covalently attached biotins mediate the transfer of carboxyl groups between distant active sites. In this chapter, some of the recent findings on pyruvate carboxylase functioning are presented, with special focus on the structural studies of the full length enzyme. The emerging picture reveals large movements of domains that even change the overall quaternary organization of pyruvate carboxylase tetramers during catalysis.
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Affiliation(s)
- Mikel Valle
- Structural Biology Unit, Center for Cooperative Research in Biosciences, CIC bioGUNE, 48160, Derio, Spain.
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10
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Westerhold LE, Adams SL, Bergman HL, Zeczycki TN. Pyruvate Occupancy in the Carboxyl Transferase Domain of Pyruvate Carboxylase Facilitates Product Release from the Biotin Carboxylase Domain through an Intermolecular Mechanism. Biochemistry 2016; 55:3447-60. [PMID: 27254467 DOI: 10.1021/acs.biochem.6b00372] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Protein structure, ligand binding, and catalytic turnover contributes to the governance of catalytic events occurring at spatially distinct domains in multifunctional enzymes. Coordination of these catalytic events partially rests on the ability of spatially discrete active sites to communicate with other allosteric and active sites on the same polypeptide chain (intramolecular) or on different polypeptide chains (intermolecular) within the holoenzyme. Often, communication results in long-range effects on substrate binding or product release. For example, pyruvate binding to the carboxyl transferase (CT) domain of pyruvate carboxylase (PC) increases the rate of product release in the biotin carboxylase (BC) domain. In order to address how CT domain ligand occupancy is "sensed" by other domains, we generated functional, mixed hybrid tetramers using the E218A (inactive BC domain) and T882S (low pyruvate binding, low activity) mutant forms of PC. The apparent Ka pyruvate for the pyruvate-stimulated release of Pi catalyzed by the T882S:E218A[1:1] hybrid tetramer was comparable to the wild-type enzyme and nearly 10-fold lower than that for the T882S homotetramer. In addition, the ratio of the rates of oxaloacetate formation to Pi release for the WT:T882S[1:1] and E218A:T882S[1:1] hybrid tetramer-catalyzed reactions was 0.5 and 0.6, respectively, while the T882S homotetramer exhibited a near 1:1 coupling of the two domains, suggesting that the mechanisms coordinating catalytic events is more complicated that we initially assumed. The results presented here are consistent with an intermolecular communication mechanism, where pyruvate binding to the CT domain is "sensed" by domains on a different polypeptide chain within the tetramer.
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Affiliation(s)
- Lauren E Westerhold
- Department of Biochemistry and Molecular Biology and the ‡East Carolina Diabetes and Obesity Institute, Brody School of Medicine at East Carolina University , Greenville, North Carolina 27834, United States
| | - Stephanie L Adams
- Department of Biochemistry and Molecular Biology and the ‡East Carolina Diabetes and Obesity Institute, Brody School of Medicine at East Carolina University , Greenville, North Carolina 27834, United States
| | - Hanna L Bergman
- Department of Biochemistry and Molecular Biology and the ‡East Carolina Diabetes and Obesity Institute, Brody School of Medicine at East Carolina University , Greenville, North Carolina 27834, United States
| | - Tonya N Zeczycki
- Department of Biochemistry and Molecular Biology and the ‡East Carolina Diabetes and Obesity Institute, Brody School of Medicine at East Carolina University , Greenville, North Carolina 27834, United States
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