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Johnston ML, Bonett EM, DeColli AA, Freel Meyers CL. Antibacterial Target DXP Synthase Catalyzes the Cleavage of d-Xylulose 5-Phosphate: a Study of Ketose Phosphate Binding and Ketol Transfer Reaction. Biochemistry 2022; 61:1810-1823. [PMID: 35998648 PMCID: PMC9531112 DOI: 10.1021/acs.biochem.2c00274] [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: 11/28/2022]
Abstract
The bacterial enzyme 1-deoxy-d-xylulose 5-phosphate synthase (DXPS) catalyzes the formation of DXP from pyruvate and d-glyceraldehyde 3-phosphate (d-GAP) in a thiamin diphosphate (ThDP)-dependent manner. In addition to its role in isoprenoid biosynthesis, DXP is required for ThDP and pyridoxal phosphate biosynthesis. Due to its function as a branch-point enzyme and its demonstrated substrate and catalytic promiscuity, we hypothesize that DXPS could be key for bacterial adaptation in the dynamic metabolic landscape during infection. Prior work in the Freel Meyers laboratory has illustrated that DXPS displays relaxed specificity toward donor and acceptor substrates and varies acceptor specificity according to the donor used. We have reported that DXPS forms dihydroxyethyl (DHE)ThDP from ketoacid or aldehyde donor substrates via decarboxylation and deprotonation, respectively. Here, we tested other DHE donors and found that DXPS cleaves d-xylulose 5-phosphate (X5P) at C2-C3, producing DHEThDP through a third mechanism involving d-GAP elimination. We interrogated DXPS-catalyzed reactions using X5P as a donor substrate and illustrated (1) production of a semi-stable enzyme-bound intermediate and (2) O2, H+, and d-erythrose 4-phosphate act as acceptor substrates, highlighting a new transketolase-like activity of DXPS. Furthermore, we examined X5P binding to DXPS and suggest that the d-GAP binding pocket plays a crucial role in X5P binding and turnover. Overall, this study reveals a ketose-cleavage reaction catalyzed by DXPS, highlighting the remarkable flexibility for donor substrate usage by DXPS compared to other C-C bond-forming enzymes.
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Affiliation(s)
- Melanie L. Johnston
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Eucolona M. Bonett
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | | | - Caren L. Freel Meyers
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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2
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Prajapati S, Rabe von Pappenheim F, Tittmann K. Frontiers in the enzymology of thiamin diphosphate-dependent enzymes. Curr Opin Struct Biol 2022; 76:102441. [PMID: 35988322 DOI: 10.1016/j.sbi.2022.102441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 07/07/2022] [Accepted: 07/11/2022] [Indexed: 11/25/2022]
Abstract
Enzymes that use thiamin diphosphate (ThDP), the biologically active derivative of vitamin B1, as a cofactor play important roles in cellular metabolism in all domains of life. The analysis of ThDP enzymes in the past decades have provided a general framework for our understanding of enzyme catalysis of this protein family. In this review, we will discuss recent advances in the field that include the observation of "unusual" reactions and reaction intermediates that highlight the chemical versatility of the thiamin cofactor. Further topics cover the structural basis of cooperativity of ThDP enzymes, novel insights into the mechanism and structure of selected enzymes, and the discovery of "superassemblies" as reported, for example, acetohydroxy acid synthase. Finally, we summarize recent findings in the structural organisation and mode of action of 2-keto acid dehydrogenase multienzyme complexes and discuss future directions of this exciting research field.
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Affiliation(s)
- Sabin Prajapati
- Department of Molecular Enzymology, Göttingen Center of Molecular Biosciences, Georg-August University Göttingen, Julia-Lermontowa-Weg 3, D-37077 Göttingen, Germany; Max-Planck-Institute for Multidisciplinary Sciences, Am Fassberg 11, D-37077 Göttingen, Germany.
| | - Fabian Rabe von Pappenheim
- Department of Molecular Enzymology, Göttingen Center of Molecular Biosciences, Georg-August University Göttingen, Julia-Lermontowa-Weg 3, D-37077 Göttingen, Germany; Max-Planck-Institute for Multidisciplinary Sciences, Am Fassberg 11, D-37077 Göttingen, Germany.
| | - Kai Tittmann
- Department of Molecular Enzymology, Göttingen Center of Molecular Biosciences, Georg-August University Göttingen, Julia-Lermontowa-Weg 3, D-37077 Göttingen, Germany; Max-Planck-Institute for Multidisciplinary Sciences, Am Fassberg 11, D-37077 Göttingen, Germany.
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3
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Xie L, Zang X, Cheng W, Zhang Z, Zhou J, Chen M, Tang Y. Harzianic Acid from Trichoderma afroharzianum Is a Natural Product Inhibitor of Acetohydroxyacid Synthase. J Am Chem Soc 2021; 143:10.1021/jacs.1c03988. [PMID: 34132537 PMCID: PMC8674378 DOI: 10.1021/jacs.1c03988] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Acetohydroxyacid synthase (AHAS) is the first enzyme in the branched-chain amino acid biosynthetic pathway and is a validated target for herbicide and fungicide development. Here we report harzianic acid (HA, 1) produced by the biocontrol fungus Trichoderma afroharzianum t-22 (Tht22) as a natural product inhibitor of AHAS. The biosynthetic pathway of HA was elucidated with heterologous reconstitution. Guided by a putative self-resistance enzyme in the genome, HA was biochemically demonstrated to be a selective inhibitor of fungal AHAS, including those from phytopathogenic fungi. In addition, HA can inhibit a common resistant variant of AHAS in which the active site proline is mutated. Structural analysis of AHAS complexed with HA revealed the molecular basis of competitive inhibition, which differs from all known commercial AHAS inhibitors. The alternative binding mode also rationalizes the selectivity of HA, as well as effectiveness toward resistant mutants. A proposed role of HA biosynthesis by Tht22 in the rhizosphere is discussed based on the data.
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Affiliation(s)
- Linan Xie
- Department of Chemical and Biomolecular Engineering, University of California Los Angeles, Los Angeles, California 90095, United States
- Biotechnology Research Institute, The Chinese Academy of Agricultural Sciences, 12 Zhongguancun South Street, Beijing 100081, P.R. China
| | - Xin Zang
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Shanghai 200032, China
| | - Wei Cheng
- Department of Chemical and Biomolecular Engineering, University of California Los Angeles, Los Angeles, California 90095, United States
- State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, China
| | - Zhuan Zhang
- Texas Therapeutics Institute, the Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, Texas 77054, United States
| | - Jiahai Zhou
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Shanghai 200032, China
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Mengbin Chen
- Department of Chemical and Biomolecular Engineering, University of California Los Angeles, Los Angeles, California 90095, United States
| | - Yi Tang
- Department of Chemical and Biomolecular Engineering, University of California Los Angeles, Los Angeles, California 90095, United States
- Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California 90095, United States
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4
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Alvarado O, García-Meseguer R, Ruiz-Pernía JJ, Tuñon I, Delgado EJ. Mechanistic study of the biosynthesis of R-phenylacetylcarbinol by acetohydroxyacid synthase enzyme using hybrid quantum mechanics/molecular mechanics simulations. Arch Biochem Biophys 2021; 707:108849. [PMID: 33832752 DOI: 10.1016/j.abb.2021.108849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The biosynthesis of R-phenylacetylcarbinol (R-PAC) by the acetohydroxy acid synthase, (AHAS) is addressed by molecular dynamics simulations (MD), hybrid quantum mechanics/molecular mechanics (QM/MM), and QM/MM free energy calculations. The results show the reaction starts with the nucleophilic attack of the C2α atom of the HEThDP intermediate on the Cβ atom of the carbonyl group of benzaldehyde substrate via the formation of a transition state (TS1) with the HEThDP intermediate under 4'-aminopyrimidium (APH+) form. The calculated activation free energy for this step is 17.4 kcal mol-1 at 27 °C. From this point, the reaction continues with the abstraction of Hβ atom of the HEThDP intermediate by the Oβ atom of benzaldehyde to form the intermediate I. The reaction is completed with the cleavage of the bond C2α-C2 to form the product R-PAC and to regenerate the ylide intermediate under the APH+ form, allowing in this way to reinitiate to the catalytic cycle once more. The calculated activation barrier for this last step is 15.9 kcal mol-1 at 27 °C.
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Affiliation(s)
- Omar Alvarado
- Departamento de Físico-Química, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile; Departamento de Química, Facultad de Ciencias, Universidad del Bío-Bío, Avenida Collao 1202, Concepción, Chile
| | - Rafael García-Meseguer
- School of Mathematics, University of Bristol, Bristol, UK; Department of Physical Chemistry, Universitat de Valencia, 46100, Burjassot, Spain
| | | | - Iñaki Tuñon
- Department of Physical Chemistry, Universitat de Valencia, 46100, Burjassot, Spain
| | - Eduardo J Delgado
- Departamento de Físico-Química, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile.
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5
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Alvarado O, García-Meseguer R, Ruiz-Pernía JJ, Tuñon I, Delgado EJ. Mechanistic study of the biosynthesis of R-phenylcarbinol by acetohydroxyacid synthase enzyme using hybrid quantum mechanics/molecular mechanics simulations. Arch Biochem Biophys 2021; 701:108807. [PMID: 33587902 DOI: 10.1016/j.abb.2021.108807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 02/06/2021] [Accepted: 02/08/2021] [Indexed: 11/26/2022]
Abstract
The biosynthesis of R-phenylacetylcarbinol (R-PAC) by the acetohydroxy acid synthase, (AHAS) is addressed by molecular dynamics simulations (MD), hybrid quantum mechanics/molecular mechanics (QM/MM), and QM/MM free energy calculations. The results show the reaction starts with the nucleophilic attack of the C2α atom of the HEThDP intermediate on the Cβ atom of the carbonyl group of benzaldehyde substrate via the formation of a transition state (TS1) with the HEThDP intermediate under 4'-aminopyrimidium (APH+) form. The calculated activation free energy for this step is 17.4kcal mol-1 at 27 °C. From this point, the reaction continues with the abstraction of Hβ atom of the HEThDP intermediate by the Oβ atom of benzaldehyde to form the intermediate I. The reaction is completed with the cleavage of the bond C2α-C2 to form the product R-PAC and to regenerate the ylide intermediate under the APH+ form, allowing in this way to reinitiate to the catalytic cycle once more. The calculated activation barrier for this last step is 15.9kcal mol-1 at 27 °C.
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Affiliation(s)
- Omar Alvarado
- Departamento de Físico-Química, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile; Departamento de Química, Facultad de Ciencias, Universidad del Bío-Bío, Avenida Collao 1202, Concepción, Chile
| | - Rafael García-Meseguer
- School of Mathematics, University of Bristol, Bristol, United Kingdom; Department of Physical Chemistry, Universitat de Valencia, 46100, Burjassot, Spain
| | | | - Iñaki Tuñon
- Department of Physical Chemistry, Universitat de Valencia, 46100, Burjassot, Spain
| | - Eduardo J Delgado
- Departamento de Físico-Química, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile.
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6
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Luo G, Zhao N, Jiang S, Zheng S. Application of RecET-Cre/loxP system in Corynebacterium glutamicum ATCC14067 for L-leucine production. Biotechnol Lett 2020; 43:297-306. [PMID: 32936374 DOI: 10.1007/s10529-020-03000-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 09/03/2020] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To explore the RecET-Cre/loxP system for chromosomal replacement of promoter and its application on enhancement L-leucine production in Corynebacterium glutamicum (C. glutamicum) ATCC14067. RESULTS The RecET-Cre/loxP system was used to achieve the chromosomal replacement of promoter in C. glutamicum ATCC14067 to adjust the metabolic flux involving the L-leucine synthetic pathway. First, leuAr_13032 from C. glutamicum ATCC13032 which carried two mutations was overexpressed to release enzyme feedback inhibition. Then, comparing different mutations in ilvBNC gene clusters, the results indicated that ilvBNC_CP was most effective to enhance the metabolic flux of pyruvate towards L-leucine synthesis. The promoters of pck, odx and pyk2 were overexpressed under the strong promoter Peftu or Psod to improve the supply of pyruvate. Besides, the promoter PilvBNC was employed to dynamically control the transcription level of icd due to its attenuation mechanism by responding to the concentration of L-leucine. The final engineered strain produced 14.05 g L-leucine/L in flask cultivation. CONCLUSION The RecET-Cre/loxP system is effective for gene manipulation in C. glutamicum ATCC14067. Besides, the results demonstrate the potential of C. glutamicum ATCC14067 for L-leucine production and provide new targets and strategies for strain development.
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Affiliation(s)
- Guangjuan Luo
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China
- Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China
| | - Nannan Zhao
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China
- Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China
| | - Shibo Jiang
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China
- Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China
| | - Suiping Zheng
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China.
- Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China.
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7
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Zhang Y, Liu Y, Zhang S, Ma W, Wang J, Yin L, Wang X. Metabolic engineering of Corynebacterium glutamicum WM001 to improve l-isoleucine production. Biotechnol Appl Biochem 2020; 68:568-584. [PMID: 32474971 DOI: 10.1002/bab.1963] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 05/29/2020] [Indexed: 01/02/2023]
Abstract
In this study, l-isoleucine production in Corynebacterium glutamicum WM001 was improved by deleting three genes in the genome, replacing the native promoter of ilvA in the genome, and overexpression of five genes in an alr-based auxotrophic complementation expression system. The three genes deleted in the genome are alaT, brnQ, and alr. Deletion of alaT improved l-isoleucine production by increasing the supply of pyruvate, whereas deletion of brnQ improved l-isoleucine production by blocking the uptake of extracellular l-isoleucine. Exchange of the native promoter of ilvA with promoter tac or tacM could contribute to l-isoleucine production by increasing 2-ketobutyric acid; tac is better than tacM for improving l-isoleucine yield. Different combinations of the genes ilvBN, ppnK, lrp, and brnFE were overexpressed in an alr-based auxotrophic complementation expression system to further improve l-isoleucine production, and the best yield after 72-H flask fermentation was obtained from the strain WM005/pYCW-1-ilvBN2-ppnK1. Without addition of any antibiotics, WM005/pYCW-1-ilvBN2-ppnK1 could produce 32.1 g/L l-isoleucine after 72-H fed-batch fermentation, which is 34.3% increase compared with the original strain WM001.
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Affiliation(s)
- Yanchao Zhang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, People's Republic of China
| | - Yadi Liu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, People's Republic of China
| | - Shuyan Zhang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, People's Republic of China
| | - Wenjian Ma
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, People's Republic of China
| | - Jianli Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, People's Republic of China
| | - Lianghong Yin
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, People's Republic of China
| | - Xiaoyuan Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.,State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, People's Republic of China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, People's Republic of China
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8
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Xie Y, Zhang C, Wang Z, Wei C, Liao N, Wen X, Niu C, Yi L, Wang Z, Xi Z. Fluorogenic Assay for Acetohydroxyacid Synthase: Design and Applications. Anal Chem 2019; 91:13582-13590. [PMID: 31603309 DOI: 10.1021/acs.analchem.9b02739] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Acetohydroxyacid synthase (AHAS) exists in plants and many microorganisms (including gut flora) but not in mammals, making it an attractive drug target. Fluorescent-based methods should be practical for high-throughput screening of inhibitors. Herein, we describe the development of the first AHAS fluorogenic assay based on an intramolecular charge transfer (ICT)-based fluorescent probe. The assay is facile, sensitive, and continuous and can be applied toward various AHASs from different species, AHAS mutants, and crude cell lysates. The fluorogenic assay was successfully applied for (1) high-throughput screening of commerical herbicides toward different AHASs for choosing matching herbicides, (2) identification of a Soybean AHAS gene with broad-spectrum herbicide resistance, and (3) identification of selective inhibitors toward intestinal-bacterial AHASs. Among the AHAS inhibitors, an active agent was found for selective inhibition of obesity-associated Ruminococcus torques growth, implying the possibility of AHAS inhibitors for the ultimate goal toward antiobesity therapeutics. The fluorogenic assay opens the door for high-throughput programs in AHAS-related fields, and the design principle might be applied for development of fluorogenic assays of other synthases.
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Affiliation(s)
- Yonghui Xie
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, National Pesticide Engineering Research Center (Tianjin), College of Chemistry , Nankai University , Tianjin 300071 , P. R. China
| | - Changyu Zhang
- State Key Laboratory of Organic-Inorganic Composites and Beijing Key Lab of Bioprocess , Beijing University of Chemical Technology (BUCT) , Beijing 100029 , P. R. China
| | - Zhihua Wang
- State Key Laboratory of Bioreactor Engineering , East China University of Science and Technology , 130 Meilong Road , Shanghai 200237 , P. R. China
| | - Chao Wei
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, National Pesticide Engineering Research Center (Tianjin), College of Chemistry , Nankai University , Tianjin 300071 , P. R. China
| | - Ningjing Liao
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, National Pesticide Engineering Research Center (Tianjin), College of Chemistry , Nankai University , Tianjin 300071 , P. R. China
| | - Xin Wen
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, National Pesticide Engineering Research Center (Tianjin), College of Chemistry , Nankai University , Tianjin 300071 , P. R. China
| | - Congwei Niu
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, National Pesticide Engineering Research Center (Tianjin), College of Chemistry , Nankai University , Tianjin 300071 , P. R. China
| | - Long Yi
- State Key Laboratory of Organic-Inorganic Composites and Beijing Key Lab of Bioprocess , Beijing University of Chemical Technology (BUCT) , Beijing 100029 , P. R. China.,Collaborative Innovation Center of Chemical Science and Engineering , Nankai University , Tianjin 300071 , P. R. China
| | - Zejian Wang
- State Key Laboratory of Bioreactor Engineering , East China University of Science and Technology , 130 Meilong Road , Shanghai 200237 , P. R. China
| | - Zhen Xi
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, National Pesticide Engineering Research Center (Tianjin), College of Chemistry , Nankai University , Tianjin 300071 , P. R. China.,Collaborative Innovation Center of Chemical Science and Engineering , Nankai University , Tianjin 300071 , P. R. China
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9
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Liu Y, Wang X, Zhan J, Hu J. The 138th residue of acetohydroxyacid synthase in Corynebacterium glutamicum is important for the substrate binding specificity. Enzyme Microb Technol 2019; 129:109357. [DOI: 10.1016/j.enzmictec.2019.06.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 05/12/2019] [Accepted: 06/01/2019] [Indexed: 11/28/2022]
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10
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Qin M, Song H, Dai X, Chan C, Chan W, Guo Z. Single‐Turnover Kinetics Reveal a Distinct Mode of Thiamine Diphosphate‐Dependent Catalysis in Vitamin K Biosynthesis. Chembiochem 2018; 19:1514-1522. [DOI: 10.1002/cbic.201800143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Indexed: 01/09/2023]
Affiliation(s)
- Mingming Qin
- Department of ChemistryThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
| | - Haigang Song
- Department of ChemistryThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
- Present address: Division of Structural BiologyWellcome Trust Centre of Human GenomicsUniversity of Oxford Roosevelt Drive Oxford OX3 7BN UK
| | - Xin Dai
- Department of ChemistryThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
| | - Chi‐Kong Chan
- Department of ChemistryThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
- Environmental Science ProgramThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
| | - Wan Chan
- Department of ChemistryThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
- Environmental Science ProgramThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
| | - Zhihong Guo
- Department of ChemistryThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
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11
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Ruszczycky MW, Liu HW. Theory and Application of the Relationship Between Steady-State Isotope Effects on Enzyme Intermediate Concentrations and Net Rate Constants. Methods Enzymol 2017; 596:459-499. [PMID: 28911781 PMCID: PMC5837895 DOI: 10.1016/bs.mie.2017.07.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Steady-state kinetic isotope effects on enzyme-catalyzed reactions are often interpreted in terms of the microscopic rate constants associated with the elementary reactions of interest. Unfortunately, this approach can lead to confusion, especially when more than one elementary reaction is isotopically sensitive, because it forces one to consider the full catalytic cycle one step at a time rather than as a complete whole. Herein we argue that shifting focus from intrinsic effects to net rate constants and enzyme intermediate concentrations provides a more natural and holistic interpretation by which the effects of partial rate limitation are more easily understood. In doing so, we demonstrate how the experimental determination of isotope effects on enzyme intermediate concentrations allows a direct determination of isotope effects on net rate constants. The chapter is divided into three main sections. The first outlines the basic theory and its interpretation. The second discusses an application of the theory in the study of the radical SAM enzyme DesII. The final section then provides the complete mathematical treatment.
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Affiliation(s)
| | - Hung-Wen Liu
- University of Texas at Austin, Austin, TX, United States
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12
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Liu Y, Li Y, Wang X. Molecular evolution of acetohydroxyacid synthase in bacteria. Microbiologyopen 2017; 6. [PMID: 28782269 PMCID: PMC5727371 DOI: 10.1002/mbo3.524] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 06/21/2017] [Accepted: 06/29/2017] [Indexed: 11/16/2022] Open
Abstract
Acetohydroxyacid synthase (AHAS) is the key enzyme in the biosynthetic pathways of branched chain amino acids in bacteria. Since it does not exist in animal and plant cells, AHAS is an attractive target for developing antimicrobials and herbicides. In some bacteria, there is a single copy of AHAS, while in others there are multiple copies. Therefore, it is necessary to investigate the origin and evolutionary pathway of various AHASs in bacteria. In this study, all the available protein sequences of AHAS in bacteria were investigated, and an evolutionary model of AHAS in bacteria is proposed, according to gene structure, organization and phylogeny. Multiple copies of AHAS in some bacteria might be evolved from the single copy of AHAS, the ancestor. Gene duplication, domain deletion and horizontal gene transfer might occur during the evolution of this enzyme. The results show the biological significance of AHAS, help to understand the functions of various AHASs in bacteria, and would be useful for developing industrial production strains of branched chain amino acids or novel antimicrobials.
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Affiliation(s)
- Yadi Liu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,School of Biotechnology, Jiangnan University, Wuxi, China
| | - Yanyan Li
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Xiaoyuan Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,School of Biotechnology, Jiangnan University, Wuxi, China.,Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, China
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13
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Alvarado O, Lizana I, Jaña G, Tuñon I, Delgado E. A DFT study on the chiral synthesis of R-phenylacetyl carbinol within the quantum chemical cluster approach. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.03.066] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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14
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Mechanistic and Structural Insight to an Evolved Benzoylformate Decarboxylase with Enhanced Pyruvate Decarboxylase Activity. Catalysts 2016. [DOI: 10.3390/catal6120190] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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15
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Liu Y, Li Y, Wang X. Acetohydroxyacid synthases: evolution, structure, and function. Appl Microbiol Biotechnol 2016; 100:8633-49. [DOI: 10.1007/s00253-016-7809-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 07/28/2016] [Accepted: 08/12/2016] [Indexed: 10/21/2022]
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16
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Functional evaluation of residues in the herbicide-binding site of Mycobacterium tuberculosis acetohydroxyacid synthase by site-directed mutagenesis. Enzyme Microb Technol 2015. [DOI: 10.1016/j.enzmictec.2015.06.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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17
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Abstract
DesII is a member of the radical SAM family of enzymes that catalyzes radical-mediated transformations of TDP-4-amino-4,6-didexoy-D-glucose as well as other sugar nucleotide diphosphates. Like nearly all radical SAM enzymes, the reactions begin with the reductive homolysis of SAM to produce a 5'-deoxyadenosyl radical which is followed by regiospecific hydrogen atom abstraction from the substrate. What happens next, however, depends on the nature of the substrate radical so produced. In the case of the biosynthetically relevant substrate, a radical-mediated deamination ensues; however, when this amino group is replaced with a hydroxyl, one instead observes dehydrogenation. The factors that govern the fate of the initially generated substrate radical as well as the mechanistic details underlying these transformations have been a key focus of research into the chemistry of DesII. This review will discuss recent discoveries pertaining to the enzymology of DesII, how it may relate to understanding other radical-mediated lyases and dehydrogenases and the working hypotheses currently being investigated regarding the mechanism of DesII catalysis.
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Affiliation(s)
- Mark W. Ruszczycky
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States
| | - Hung-wen Liu
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
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18
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Sánchez L, Jaña GA, Delgado EJ. A QM/MM study on the reaction pathway leading to 2-Aceto-2-hydroxybutyrate in the catalytic cycle of AHAS. J Comput Chem 2014; 35:488-94. [DOI: 10.1002/jcc.23523] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 11/30/2013] [Accepted: 12/15/2013] [Indexed: 11/05/2022]
Affiliation(s)
- Leslie Sánchez
- Computational Biological Chemistry Group, Faculty of Chemical Sciences; Universidad de Concepción; Concepción
| | - Gonzalo A. Jaña
- Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Sede Concepción; Universidad Andrés Bello; Concepcion
| | - Eduardo J. Delgado
- Computational Biological Chemistry Group, Faculty of Chemical Sciences; Universidad de Concepción; Concepción
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Electron density reactivity indexes of the tautomeric/ionization forms of thiamin diphosphate. J Mol Model 2013; 19:3799-803. [PMID: 23793740 DOI: 10.1007/s00894-013-1908-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 06/03/2013] [Indexed: 10/26/2022]
Abstract
The generation of the highly reactive ylide in thiamin diphosphate catalysis is analyzed in terms of the nucleophilicity of key atoms, by means of density functional calculations at X3LYP/6-31++G(d,p) level of theory. The Fukui functions of all tautomeric/ionization forms are calculated in order to assess their reactivity. The results allow to conclude that the highly conserved glutamic residue does not protonate the N1' atom of the pyrimidyl ring, but it participates in a strong hydrogen bonding, stabilizing the eventual negative charge on the nitrogen, in all forms involved in the ylide generation. This condition provides the necessary reactivity on key atoms, N4' and C2, to carry out the formation of the ylide required to initiate the catalytic cycle of ThDP-dependent enzymes. This study represents a new approach for the ylide formation in ThDP catalysis.
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20
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Balakrishnan A, Jordan F, Nathan CF. Influence of allosteric regulators on individual steps in the reaction catalyzed by Mycobacterium tuberculosis 2-hydroxy-3-oxoadipate synthase. J Biol Chem 2013; 288:21688-702. [PMID: 23760263 DOI: 10.1074/jbc.m113.465419] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Allosteric regulation often controls key branch points in metabolic processes. Mycobacterium tuberculosis 2-hydroxy-3-oxoadipate synthase (HOAS), a thiamin diphosphate (ThDP)-dependent enzyme, produces 2-hydroxy-3-oxoadipate using 2-ketoglutarate and glyoxylate. The proposed chemical mechanism in analogy with other ThDP-dependent carboligases involves multiple ThDP-bound covalent intermediates. Acetyl coenzyme A is an activator, and GarA, a forkhead association domain-containing protein known to regulate glutamate metabolism, is an allosteric inhibitor of HOAS. Steady state kinetics using assays to study the first half and the full catalytic cycle suggested that the regulators act at different steps in the overall mechanism. To explore the modes of regulation and to test the effects on individual catalytic steps, we performed circular dichroism (CD) studies using a non-decarboxylatable 2-ketoglutarate analog and determined the distribution of ThDP-bound covalent intermediates during the steady state of the HOAS reaction using one-dimensional (1)H gradient carbon heteronuclear single quantum coherence NMR. The results suggest that acetyl coenzyme A acts as a mixed V and K type activator and predominantly affects the predecarboxylation steps. GarA does not inhibit the formation of the predecarboxylation analog and does not affect the accumulation of the postdecarboxylation covalent intermediate derived from 2-ketoglutarate; however, it decreases the abundance of the product ThDP adduct in the HOAS pathway. Thus, the two regulators act on different halves of the catalytic cycle in an unusual regulatory regime.
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Affiliation(s)
- Anand Balakrishnan
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York 10065, USA
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21
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EPR-kinetic isotope effect study of the mechanism of radical-mediated dehydrogenation of an alcohol by the radical SAM enzyme DesII. Proc Natl Acad Sci U S A 2013; 110:2088-93. [PMID: 23329328 DOI: 10.1073/pnas.1209446110] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The radical S-adenosyl-L-methionine enzyme DesII from Streptomyces venezuelae is able to oxidize the C3 hydroxyl group of TDP-D-quinovose to the corresponding ketone via an α-hydroxyalkyl radical intermediate. It is unknown whether electron transfer from the radical intermediate precedes or follows its deprotonation, and answering this question would offer considerable insight into the mechanism by which the small but important class of radical-mediated alcohol dehydrogenases operate. This question can be addressed by measuring steady-state kinetic isotope effects (KIEs); however, their interpretation is obfuscated by the degree to which the steps of interest limit catalysis. To circumvent this problem, we measured the solvent deuterium KIE on the saturating steady-state concentration of the radical intermediate using electron paramagnetic resonance spectroscopy. The resulting value, 0.22 ± 0.03, when combined with the solvent deuterium KIE on the maximum rate of turnover (V) of 1.8 ± 0.2, yielded a KIE of 8 ± 2 on the net rate constant specifically associated with the α-hydroxyalkyl radical intermediate. This result implies that electron transfer from the radical intermediate does not precede deprotonation. Further analysis of these isotope effects, along with the pH dependence of the steady-state kinetic parameters, likewise suggests that DesII must be in the correct protonation state for initial generation of the α-hydroxyalkyl radical. In addition to providing unique mechanistic insights, this work introduces a unique approach to investigating enzymatic reactions using KIEs.
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22
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Zhao Y, Wen X, Niu C, Xi Z. Arginine 26 and Aspartic Acid 69 of the Regulatory Subunit are Key Residues of Subunits Interaction of Acetohydroxyacid Synthase Isozyme III fromE. coli. Chembiochem 2012; 13:2445-54. [DOI: 10.1002/cbic.201200362] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Indexed: 11/08/2022]
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23
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Belenky I, Steinmetz A, Vyazmensky M, Barak Z, Tittmann K, Chipman DM. Many of the functional differences between acetohydroxyacid synthase (AHAS) isozyme I and other AHASs are a result of the rapid formation and breakdown of the covalent acetolactate-thiamin diphosphate adduct in AHAS I. FEBS J 2012; 279:1967-79. [DOI: 10.1111/j.1742-4658.2012.08577.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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24
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Barak Z, Chipman DM. Allosteric regulation in Acetohydroxyacid Synthases (AHASs) – Different structures and kinetic behavior in isozymes in the same organisms. Arch Biochem Biophys 2012; 519:167-74. [DOI: 10.1016/j.abb.2011.11.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 11/25/2011] [Accepted: 11/29/2011] [Indexed: 10/14/2022]
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25
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Gedi V, Yoon MY. Bacterial acetohydroxyacid synthase and its inhibitors - a summary of their structure, biological activity and current status. FEBS J 2012; 279:946-63. [DOI: 10.1111/j.1742-4658.2012.08505.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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26
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Jaña G, Jiménez V, Villà-Freixa J, Prat-Resina X, Delgado E, Alderete JB. A QM/MM study on the last two steps of the catalytic cycle of acetohydroxyacid synthase. COMPUT THEOR CHEM 2011. [DOI: 10.1016/j.comptc.2011.02.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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27
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Vyazmensky M, Steinmetz A, Meyer D, Golbik R, Barak Z, Tittmann K, Chipman DM. Significant Catalytic Roles for Glu47 and Gln 110 in All Four of the C−C Bond-Making and -Breaking Steps of the Reactions of Acetohydroxyacid Synthase II. Biochemistry 2011; 50:3250-60. [DOI: 10.1021/bi102051h] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Maria Vyazmensky
- Ben-Gurion University of the Negev, Department of Life Sciences, Beer-Sheva 84105, Israel
| | - Andrea Steinmetz
- Georg-August University Göttingen, Albrecht-von-Haller-Institute and Göttingen Centre for Molecular Biosciences, Ernst-Caspari-Haus, Department of Bioanalytics, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
- Martin-Luther University Halle-Wittenberg, Institute for Biochemistry and Biotechnology, Kurt-Mothes-Strasse 3, 06120 Halle/Saale, Germany
| | - Danilo Meyer
- Georg-August University Göttingen, Albrecht-von-Haller-Institute and Göttingen Centre for Molecular Biosciences, Ernst-Caspari-Haus, Department of Bioanalytics, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
- Martin-Luther University Halle-Wittenberg, Institute for Biochemistry and Biotechnology, Kurt-Mothes-Strasse 3, 06120 Halle/Saale, Germany
| | - Ralph Golbik
- Martin-Luther University Halle-Wittenberg, Institute for Biochemistry and Biotechnology, Kurt-Mothes-Strasse 3, 06120 Halle/Saale, Germany
| | - Ze'ev Barak
- Ben-Gurion University of the Negev, Department of Life Sciences, Beer-Sheva 84105, Israel
| | - Kai Tittmann
- Georg-August University Göttingen, Albrecht-von-Haller-Institute and Göttingen Centre for Molecular Biosciences, Ernst-Caspari-Haus, Department of Bioanalytics, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
- Martin-Luther University Halle-Wittenberg, Institute for Biochemistry and Biotechnology, Kurt-Mothes-Strasse 3, 06120 Halle/Saale, Germany
| | - David M. Chipman
- Ben-Gurion University of the Negev, Department of Life Sciences, Beer-Sheva 84105, Israel
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28
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Jaña G, Jiménez V, Villà-Freixa J, Prat-Resina X, Delgado E, Alderete J. Computational study on the carboligation reaction of acetohidroxyacid synthase: new approach on the role of the HEThDP- intermediate. Proteins 2010; 78:1774-88. [PMID: 20225259 DOI: 10.1002/prot.22693] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Acetohydroxyacid synthase (AHAS) is a thiamin diphosphate dependent enzyme that catalyses the decarboxylation of pyruvate to yield the hydroxyethyl-thiamin diphosphate (ThDP) anion/enamine intermediate (HEThDP(-)). This intermediate reacts with a second ketoacid to form acetolactate or acetohydroxybutyrate as products. Whereas the mechanism involved in the formation of HEThDP(-) from pyruvate is well understood, the role of the enzyme in controlling the carboligation reaction of HEThDP(-) has not been determined yet. In this work, molecular dynamics (MD) simulations were employed to identify the aminoacids involved in the carboligation stage. These MD studies were carried out over the catalytic subunit of yeast AHAS containing the reaction intermediate (HEThDP(-)) and a second pyruvate molecule. Our results suggest that additional acid-base ionizable groups are not required to promote the catalytic cycle, in contrast with earlier proposals. This finding leads us to postulate that the formation of acetolactate relies on the acid-base properties of the HEThDP(-) intermediate itself. PM3 semiempirical calculations were employed to obtain the energy profile of the proposed mechanism on a reduced model of the active site. These calculations confirm the role of HEThDP(-) intermediate as the ionizable group that promotes the carboligation and product formation steps of the catalytic cycle.
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Affiliation(s)
- Gonzalo Jaña
- Grupo de Química Teórica y Computacional, Facultad de Ciencias Químicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
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29
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Steinmetz A, Vyazmensky M, Meyer D, Barak Z, Golbik R, Chipman DM, Tittmann K. Valine 375 and Phenylalanine 109 Confer Affinity and Specificity for Pyruvate as Donor Substrate in Acetohydroxy Acid Synthase Isozyme II from Escherichia coli. Biochemistry 2010; 49:5188-99. [DOI: 10.1021/bi100555q] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andrea Steinmetz
- Albrecht-von-Haller-Institute and Göttingen Centre for Molecular Biosciences, Ernst-Caspari-Haus, Department of Bioanalytics, Georg-August University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Maria Vyazmensky
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Danilo Meyer
- Albrecht-von-Haller-Institute and Göttingen Centre for Molecular Biosciences, Ernst-Caspari-Haus, Department of Bioanalytics, Georg-August University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Ze′ev Barak
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Ralph Golbik
- Institute for Biochemistry and Biotechnology, Martin-Luther University Halle-Wittenberg, Kurt-Mothes-Strasse 3, 06120 Halle/Saale, Germany
| | - David M. Chipman
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Kai Tittmann
- Albrecht-von-Haller-Institute and Göttingen Centre for Molecular Biosciences, Ernst-Caspari-Haus, Department of Bioanalytics, Georg-August University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
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30
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Chipman DM, Barak Z, Shaanan B, Vyazmensky M, Binshtein E, Belenky I, Temam V, Steinmetz A, Golbik R, Tittmann K. Origin of the specificities of acetohydroxyacid synthases and glyoxylate carboligase. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.molcatb.2009.03.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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31
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Bruning M, Berheide M, Meyer D, Golbik R, Bartunik H, Liese A, Tittmann K. Structural and kinetic studies on native intermediates and an intermediate analogue in benzoylformate decarboxylase reveal a least motion mechanism with an unprecedented short-lived predecarboxylation intermediate. Biochemistry 2009; 48:3258-68. [PMID: 19182954 DOI: 10.1021/bi801957d] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The thiamin diphosphate- (ThDP-) dependent enzyme benzoylformate decarboxylase (BFDC) catalyzes the nonoxidative decarboxylation of benzoylformic acid to benzaldehyde and carbon dioxide. To date, no structural information for a cofactor-bound reaction intermediate in BFDC is available. For kinetic analysis, a chromophoric substrate analogue was employed that produces various absorbing intermediates during turnover but is a poor substrate with a 10(4)-fold compromised kcat. Here, we have analyzed the steady-state distribution of native intermediates by a combined chemical quench/1H NMR spectroscopic approach and estimated the net rate constants of elementary catalytic steps. At substrate saturation, carbonyl addition of the substrate to the cofactor (k' approximately 500 s-1 at 30 degrees C) and elimination of benzaldehyde (k' approximately 2.400 s-1) were found to be partially rate-determining for catalysis, whereas decarboxylation of the transient 2-mandelyl-ThDP intermediate is 1 order of magnitude faster with k' approximately 16.000 s-1, the largest rate constant of decarboxylation in any thiamin enzyme characterized so far. The X-ray structure of a predecarboxylation intermediate analogue was determined to 1.6 A after cocrystallization of BFDC from Pseudomonas putida with benzoylphosphonic acid methyl ester. In contrast to the free acid, for which irreversible phosphorylation of active center Ser26 was reported, the methyl ester forms a covalent adduct with ThDP with a similar configuration at C2alpha as observed for other thiamin enzymes. The C2-C2alpha bond of the intermediate analogue is out of plane by 7degrees, indicating strain. The phosphonate part of the adduct forms hydrogen bonds with Ser26 and His281, and the 1-OH group is held in place by interactions with His70 and the 4'-amino group of ThDP. The phenyl ring accommodates in a hydrophobic pocket formed by Phe464, Phe397, Leu109, and Leu403. A comparison with the previously determined structure of BFDC in noncovalent complex with the inhibitor (R)-mandelate suggests a least motion mechanism. Binding of benzoylphosphonic acid methyl ester to BFDC was further characterized by CD spectroscopy and stopped-flow kinetics, indicating a two-step binding mechanism with a 200-fold slower carbonyl addition to ThDP than determined for benzoylformic acid, in line with the observed slight structural reorganization of Phe464 due to steric clashes with the phosphonate moiety.
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Affiliation(s)
- Marc Bruning
- Institute of Technical Biocatalysis, Hamburg UniVersity of Technology, Denickestrasse 15, D-21073 Hamburg, Germany
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Xiong Y, Liu J, Yang GF, Zhan CG. Computational determination of fundamental pathway and activation barriers for acetohydroxyacid synthase-catalyzed condensation reactions of α-keto acids. J Comput Chem 2009; 31:1592-602. [DOI: 10.1002/jcc.21356] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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33
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Kluger R, Tittmann K. Thiamin diphosphate catalysis: enzymic and nonenzymic covalent intermediates. Chem Rev 2008; 108:1797-833. [PMID: 18491870 DOI: 10.1021/cr068444m] [Citation(s) in RCA: 216] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ronald Kluger
- Davenport Laboratories, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6 Canada.
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Kaplun A, Binshtein E, Vyazmensky M, Steinmetz A, Barak Z, Chipman DM, Tittmann K, Shaanan B. Glyoxylate carboligase lacks the canonical active site glutamate of thiamine-dependent enzymes. Nat Chem Biol 2008; 4:113-8. [PMID: 18176558 DOI: 10.1038/nchembio.62] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Accepted: 10/25/2007] [Indexed: 11/09/2022]
Abstract
Thiamine diphosphate (ThDP), a derivative of vitamin B1, is an enzymatic cofactor whose special chemical properties allow it to play critical mechanistic roles in a number of essential metabolic enzymes. It has been assumed that all ThDP-dependent enzymes exploit a polar interaction between a strictly conserved glutamate and the N1' of the ThDP moiety. The crystal structure of glyoxylate carboligase challenges this paradigm by revealing that valine replaces the conserved glutamate. Through kinetic, spectroscopic and site-directed mutagenesis studies, we show that although this extreme change lowers the rate of the initial step of the enzymatic reaction, it ensures efficient progress through subsequent steps. Glyoxylate carboligase thus provides a unique illustration of the fine tuning between catalytic stages imposed during evolution on enzymes catalyzing multistep processes.
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Affiliation(s)
- Alexander Kaplun
- Department of Life Sciences, Ben-Gurion University of the Negev, 1 Ben-Gurion Avenue, Beer-Sheva 84105, Israel
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Knoll M, Müller M, Pleiss J, Pohl M. Factors Mediating Activity, Selectivity, and Substrate Specificity for the Thiamin Diphosphate-Dependent Enzymes Benzaldehyde Lyase and Benzoylformate Decarboxylase. Chembiochem 2006; 7:1928-34. [PMID: 17051662 DOI: 10.1002/cbic.200600277] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Benzaldehyde lyase from Pseudomonas fluorescens and benzoylformate decarboxylase from Pseudomonas putida are homologous thiamin diphosphate-dependent enzymes that catalyze carboligase and carbolyase reactions. Both enzymes catalyze the formation of chiral 2-hydroxy ketones from aldehydes. However, the reverse reaction has only been observed with benzaldehyde lyase. Whereas benzaldehyde lyase is strictly R specific, the stereoselectivity of benzoylformate decarboxylase from P. putida is dependent on the structure and orientation of the substrate aldehydes. In this study, the binding sites of both enzymes were investigated by using molecular modelling studies to explain the experimentally observed differences in the activity, stereo- and enantioselectivity and substrate specificity of both enzymes. We designed a detailed illustration that describes the shape of the binding site of both enzymes and sufficiently explains the experimental effects observed with the wild-type enzymes and different variants. These findings demonstrate that steric reasons are predominantly responsible for the differences observed in the (R)-benzoin cleavage and in the formation of chiral 2-hydroxy ketones.
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Affiliation(s)
- Michael Knoll
- Institute of Technical Biochemistry, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
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36
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McCourt JA, Duggleby RG. Acetohydroxyacid synthase and its role in the biosynthetic pathway for branched-chain amino acids. Amino Acids 2006; 31:173-210. [PMID: 16699828 DOI: 10.1007/s00726-005-0297-3] [Citation(s) in RCA: 171] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Accepted: 12/09/2005] [Indexed: 11/25/2022]
Abstract
The branched-chain amino acids are synthesized by plants, fungi and microorganisms, but not by animals. Therefore, the enzymes of this pathway are potential target sites for the development of antifungal agents, antimicrobials and herbicides. Most research has focused upon the first enzyme in this biosynthetic pathway, acetohydroxyacid synthase (AHAS) largely because it is the target site for many commercial herbicides. In this review we provide a brief overview of the important properties of each enzyme within the pathway and a detailed summary of the most recent AHAS research, against the perspective of work that has been carried out over the past 50 years.
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Affiliation(s)
- J A McCourt
- School of Molecular and Microbial Sciences, University of Queensland, Brisbane, Australia
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37
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Vinogradov V, Vyazmensky M, Engel S, Belenky I, Kaplun A, Kryukov O, Barak Z, Chipman DM. Acetohydroxyacid synthase isozyme I from Escherichia coli has unique catalytic and regulatory properties. Biochim Biophys Acta Gen Subj 2006; 1760:356-63. [PMID: 16326011 DOI: 10.1016/j.bbagen.2005.10.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2005] [Revised: 09/27/2005] [Accepted: 10/20/2005] [Indexed: 11/30/2022]
Abstract
AHAS I is an isozyme of acetohydroxyacid synthase which is apparently unique to enterobacteria. It has been known for over 20 years that it has many properties which are quite different from those of the other two enterobacterial AHASs isozymes, as well as from those of "typical" AHASs which are single enzymes in a given organism. These include a unique mechanism for regulation of expression and the absence of a preference for forming acetohydroxybutyrate. We have cloned the two subunits, ilvB and ilvN, of this Escherichia coli isoenzyme and examined the enzymatic properties of the purified holoenzyme and the enzyme reconstituted from purified subunits. Unlike other AHASs, AHAS I demonstrates cooperative feedback inhibition by valine, and the kinetics fit closely to an exclusive binding model. The formation of acetolactate by AHAS I is readily reversible and acetolactate can act as substrate for alternative AHAS I-catalyzed reactions.
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Affiliation(s)
- Valerie Vinogradov
- Department of Life Sciences, Ben-Gurion University of the Negev, POB 657, Beer-Sheva 84105, Israel
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Chipman DM, Duggleby RG, Tittmann K. Mechanisms of acetohydroxyacid synthases. Curr Opin Chem Biol 2006; 9:475-81. [PMID: 16055369 DOI: 10.1016/j.cbpa.2005.07.002] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2005] [Accepted: 07/18/2005] [Indexed: 11/17/2022]
Abstract
Acetohydroxyacid synthases are thiamin diphosphate- (ThDP-) dependent biosynthetic enzymes found in all autotrophic organisms. Over the past 4-5 years, their mechanisms have been clarified and illuminated by protein crystallography, engineered mutagenesis and detailed single-step kinetic analysis. Pairs of catalytic subunits form an intimate dimer containing two active sites, each of which lies across a dimer interface and involves both monomers. The ThDP adducts of pyruvate, acetaldehyde and the product acetohydroxyacids can be detected quantitatively after rapid quenching. Determination of the distribution of intermediates by NMR then makes it possible to calculate individual forward unimolecular rate constants. The enzyme is the target of several herbicides and structures of inhibitor-enzyme complexes explain the herbicide-enzyme interaction.
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Affiliation(s)
- David M Chipman
- Department of Life Sciences, Ben-Gurion University POB 653, Beer-Sheva 84105, Israel
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McCourt JA, Pang SS, King-Scott J, Guddat LW, Duggleby RG. Herbicide-binding sites revealed in the structure of plant acetohydroxyacid synthase. Proc Natl Acad Sci U S A 2006; 103:569-73. [PMID: 16407096 PMCID: PMC1334660 DOI: 10.1073/pnas.0508701103] [Citation(s) in RCA: 213] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The sulfonylureas and imidazolinones are potent commercial herbicide families. They are among the most popular choices for farmers worldwide, because they are nontoxic to animals and highly selective. These herbicides inhibit branched-chain amino acid biosynthesis in plants by targeting acetohydroxyacid synthase (AHAS, EC 2.2.1.6). This report describes the 3D structure of Arabidopsis thaliana AHAS in complex with five sulfonylureas (to 2.5 A resolution) and with the imidazolinone, imazaquin (IQ; 2.8 A). Neither class of molecule has a structure that mimics the substrates for the enzyme, but both inhibit by blocking a channel through which access to the active site is gained. The sulfonylureas approach within 5 A of the catalytic center, which is the C2 atom of the cofactor thiamin diphosphate, whereas IQ is at least 7 A from this atom. Ten of the amino acid residues that bind the sulfonylureas also bind IQ. Six additional residues interact only with the sulfonylureas, whereas there are two residues that bind IQ but not the sulfonylureas. Thus, the two classes of inhibitor occupy partially overlapping sites but adopt different modes of binding. The increasing emergence of resistant weeds due to the appearance of mutations that interfere with the inhibition of AHAS is now a worldwide problem. The structures described here provide a rational molecular basis for understanding these mutations, thus allowing more sophisticated AHAS inhibitors to be developed. There is no previously described structure for any plant protein in complex with a commercial herbicide.
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Affiliation(s)
- Jennifer A McCourt
- School of Molecular and Microbial Sciences, University of Queensland, Brisbane QLD 4072, Australia
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Abstract
Acetohydroxyacid synthase (AHAS) is the first common enzyme in the pathway for the biosynthesis of branched-chain amino acids. Interest in the enzyme has escalated over the past 20 years since it was discovered that AHAS is the target of the sulfonylurea and imidazolinone herbicides. However, several questions regarding the reaction mechanism have remained unanswered, particularly the way in which AHAS "chooses" its second substrate. A new method for the detection of reaction intermediates enables calculation of the microscopic rate constants required to explain this phenomenon.
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Affiliation(s)
- Jennifer A McCourt
- School of Molecular and Microbial Sciences, University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
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Nemeria N, Tittmann K, Joseph E, Zhou L, Vazquez-Coll MB, Arjunan P, Hübner G, Furey W, Jordan F. Glutamate 636 of the Escherichia coli pyruvate dehydrogenase-E1 participates in active center communication and behaves as an engineered acetolactate synthase with unusual stereoselectivity. J Biol Chem 2005; 280:21473-82. [PMID: 15802265 DOI: 10.1074/jbc.m502691200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The residue Glu636 is located near the thiamine diphosphate (ThDP) binding site of the Escherichia coli pyruvate dehydrogenase complex E1 subunit (PDHc-E1), and to probe its function two variants, E636A and E636Q were created with specific activities of 2.5 and 26% compared with parental PDHc-E1. According to both fluorescence binding and kinetic assays, the E636A variant behaved according to half-of-the-sites mechanism with respect to ThDP. In contrast, with the E636Q variant a K(d,ThDP) = 4.34 microM and K(m,ThDP) = 11 microM were obtained with behavior more reminiscent of the parental enzyme. The CD spectra of both variants gave evidence for formation of the 1',4'-iminopyrimidine tautomer on binding of phosphonolactylthiamine diphosphate, a stable analog of the substrate-ThDP covalent complex. Rapid formation of optically active (R)-acetolactate by both variants, but not by the parental enzyme, was observed by CD and NMR spectroscopy. The acetolactate configuration produced by the Glu636 variants is opposite that produced by the enzyme acetolactate synthase and the Asp28-substituted variants of yeast pyruvate decarboxylase, suggesting that the active centers of the two sets of enzymes exhibit different facial selectivity (re or si) vis à vis pyruvate. The tryptic peptide map (mass spectral analysis) revealed that the Glu636 substitution changed the mobility of a loop comprising amino acid residues from the ThDP binding fold. Apparently, the residue Glu636 has important functions both in active center communication and in protecting the active center from undesirable "carboligase" side reactions.
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Affiliation(s)
- Natalia Nemeria
- Department of Chemistry, Rutgers University, Newark, New Jersey 07102, USA.
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