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Wojtyś MI, Maksymiuk W, Narczyk M, Bubić A, Ašler IL, Krzyżek P, Gościniak G, Jagusztyn-Krynicka EK, Bzowska A. Vitamin B6 inhibits activity of Helicobacter pylori adenylosuccinate synthetase and growth of reference and clinical, antibiotic-resistant H. pylori strains. J Enzyme Inhib Med Chem 2024; 39:2372734. [PMID: 39149761 DOI: 10.1080/14756366.2024.2372734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 06/07/2024] [Accepted: 06/20/2024] [Indexed: 08/17/2024] Open
Abstract
The current therapies against gastric pathogen Helicobacter pylori are ineffective in over 20% of patients. Enzymes belonging to the purine salvage pathway are considered as novel drug targets in this pathogen. Therefore, the main aim of the current study was to determine the antibacterial activity of pyridoxal 5'-phosphate (PLP), an active form of vitamin B6, against reference and clinical strains of H. pylori. Using a broad set of microbiological, physicochemical (UV absorption, LC-MS, X-ray analysis) and in silico experiments, we were able to prove that PLP inhibits adenylosuccinate synthetase (AdSS) from H. pylori by the competition with GTP (IC50eq ∼30 nM). This behaviour was attributed to formation of a Schiff base with a lysine residue (a covalent bond with Lys322 in the GTP binding site of AdSS) and was potentiated by the presence of vitamin C. This antibacterial activity of PLP gives hope for its future use against H. pylori.
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Affiliation(s)
- Marta Ilona Wojtyś
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Weronika Maksymiuk
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - Marta Narczyk
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - Ante Bubić
- Division of Physical Chemistry, Ruđer Bošković Institute, Zagreb, Croatia
| | - Ivana Leščić Ašler
- Division of Physical Chemistry, Ruđer Bošković Institute, Zagreb, Croatia
| | - Paweł Krzyżek
- Department of Microbiology, Faculty of Medicine, Wroclaw Medical University, Wroclaw, Poland
| | - Grażyna Gościniak
- Department of Microbiology, Faculty of Medicine, Wroclaw Medical University, Wroclaw, Poland
| | | | - Agnieszka Bzowska
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
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2
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Crumpton AE, Heilmann A, Aldridge S. Modulating Hydrogen Shuttling in Ammonia by Neutral and Cationic Boron-Containing Frustrated Lewis Pairs (FLPs). Angew Chem Int Ed Engl 2024; 63:e202406440. [PMID: 38818696 DOI: 10.1002/anie.202406440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 05/27/2024] [Accepted: 05/28/2024] [Indexed: 06/01/2024]
Abstract
Xanthene-backbone FLPs featuring secondary borane functions -B(ArX)H (where ArX=C6F5 (ArF) or C6Cl5 (ArCl)) have been targeted through reactions of the dihydroboranes Me2S ⋅ BArXH2 with [4,5-xanth(PR2)Li]2 (R=Ph, iPr), and investigated in the synthesis of related cationic systems via hydride abstraction. The reactivity of these systems (both cationic and charge neutral) with ammonia have been probed, with a view to probing the potential for proton shuttling via N-H bond 'activation.' We find that in the case of four-coordinate boron systems (cationic or change neutral), the N-H linkage remains intact, supported by a NH⋅⋅⋅P hydrogen bond which is worth up to 17 kcal mol-1 thermodynamically, and enabled by planarization of the flexible xanthene scaffold. For cationic three coordinate systems, N-to-P proton transfer is viable, driven by the ability of the boron centre to stabilise the [NH2]- conjugate base through N-to-B π bonding. This proton transfer can be shown to be reversible in the presence of excess ammonia, depending on the nature of the B-bound ArX group. It is viable in the case of C6F5 substituents, but is prevented by the more sterically encumbering and secondary donor-stabilising capabilities of the C6Cl5 substituent.
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Affiliation(s)
- Agamemnon E Crumpton
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
| | - Andreas Heilmann
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
| | - Simon Aldridge
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
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3
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Bowling PE, Dasgupta S, Herbert JM. Eliminating Imaginary Vibrational Frequencies in Quantum-Chemical Cluster Models of Enzymatic Active Sites. J Chem Inf Model 2024; 64:3912-3922. [PMID: 38648614 DOI: 10.1021/acs.jcim.4c00221] [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: 04/25/2024]
Abstract
In constructing finite models of enzyme active sites for quantum-chemical calculations, atoms at the periphery of the model must be constrained to prevent unphysical rearrangements during geometry relaxation. A simple fixed-atom or "coordinate-lock" approach is commonly employed but leads to undesirable artifacts in the form of small imaginary frequencies. These preclude evaluation of finite-temperature free-energy corrections, limiting thermochemical calculations to enthalpies only. Full-dimensional vibrational frequency calculations are possible by replacing the fixed-atom constraints with harmonic confining potentials. Here, we compare that approach to an alternative strategy in which fixed-atom contributions to the Hessian are simply omitted. While the latter strategy does eliminate imaginary frequencies, it tends to underestimate both the zero-point energy and the vibrational entropy while introducing artificial rigidity. Harmonic confining potentials eliminate imaginary frequencies and provide a flexible means to construct active-site models that can be used in unconstrained geometry relaxations, affording better convergence of reaction energies and barrier heights with respect to the model size, as compared to models with fixed-atom constraints.
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Affiliation(s)
- Paige E Bowling
- Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, United States
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Saswata Dasgupta
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
- Department of Chemistry and Biochemistry, University of California-San Diego, La Jolla, California 92093, United States
| | - John M Herbert
- Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, United States
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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4
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Pierce BS, Schmittou AN, York NJ, Madigan RP, Nino PF, Foss FW, Lockart MM. Improved resolution of 3-mercaptopropionate dioxygenase active site provided by ENDOR spectroscopy offers insight into catalytic mechanism. J Biol Chem 2024; 300:105777. [PMID: 38395308 PMCID: PMC10966181 DOI: 10.1016/j.jbc.2024.105777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 02/13/2024] [Accepted: 02/15/2024] [Indexed: 02/25/2024] Open
Abstract
3-mercaptopropionate (3MPA) dioxygenase (MDO) is a mononuclear nonheme iron enzyme that catalyzes the O2-dependent oxidation of thiol-bearing substrates to yield the corresponding sulfinic acid. MDO is a member of the cysteine dioxygenase family of small molecule thiol dioxygenases and thus shares a conserved sequence of active site residues (Serine-155, Histidine-157, and Tyrosine-159), collectively referred to as the SHY-motif. It has been demonstrated that these amino acids directly interact with the mononuclear Fe-site, influencing steady-state catalysis, catalytic efficiency, O2-binding, and substrate coordination. However, the underlying mechanism by which this is accomplished is poorly understood. Here, pulsed electron paramagnetic resonance spectroscopy [1H Mims electron nuclear double resonance spectroscopy] is applied to validate density functional theory computational models for the MDO Fe-site simultaneously coordinated by substrate and nitric oxide (NO), (3MPA/NO)-MDO. The enhanced resolution provided by electron nuclear double resonance spectroscopy allows for direct observation of Fe-bound substrate conformations and H-bond donation from Tyr159 to the Fe-bound NO ligand. Further inclusion of SHY-motif residues within the validated model reveals a distinct channel restricting movement of the Fe-bound NO-ligand. It has been argued that the iron-nitrosyl emulates the structure of potential Fe(III)-superoxide intermediates within the MDO catalytic cycle. While the merit of this assumption remains unconfirmed, the model reported here offers a framework to evaluate oxygen binding at the substrate-bound Fe-site and possible reaction mechanisms. It also underscores the significance of hydrogen bonding interactions within the enzymatic active site.
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Affiliation(s)
- Brad S Pierce
- Department of Chemistry & Biochemistry, University of Alabama, Tuscaloosa, Alabama, USA.
| | - Allison N Schmittou
- Department of Chemistry & Biochemistry, University of Alabama, Tuscaloosa, Alabama, USA
| | - Nicholas J York
- Department of Chemistry & Biochemistry, University of Alabama, Tuscaloosa, Alabama, USA
| | - Ryan P Madigan
- Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, Texas, USA
| | - Paula F Nino
- Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, Texas, USA
| | - Frank W Foss
- Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, Texas, USA
| | - Molly M Lockart
- Department of Chemistry and Biochemistry, Samford University, Homewood, Alabama, USA.
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5
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Li S, Shao Z, Lu C, Duan D. Isolation and functional verification of an aspartate aminotransferase gene from Neoporphyra haitanensis. BMC PLANT BIOLOGY 2023; 23:150. [PMID: 36941626 PMCID: PMC10029208 DOI: 10.1186/s12870-023-04158-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 03/08/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND Neoporphyra haitanensis is a commercial laver species in China. Aspartic acid is an important flavor amino acid, and aspartate aminotransferase (AAT) is a crucial enzyme in its biosynthesis. In this study, we cloned one AAT gene (NhAAT) from the red alga N. haitanensis and investigated its sequence structure, transcriptional expression and enzymatic characteristics. The purpose of our research is to obtain a functional AAT responsible for the biosynthesis of aspartic acid from red seaweeds, which has the potential to influence the flavor of N. haitanensis. RESULTS Sequence analysis showed that NhAAT contains a conserved domain of Aminotran_1_2, which belongs to the transaminase superfamily. The secondary structure of NhAAT is dominated by α-helix. The results of enzymatic characterization illustrated that the NhAAT has highest catalytic activity at 45 °C and pH 7.5 in both forward and reverse reactions. The calculated Km values of NhAAT was 5.67 and 6.16 mM for L-glutamic acid and L-aspartic acid, respectively. Quantitative analysis showed that the NhAAT expression of N. haitanensis collected in late harvest (Dec) was 4.5 times that of N. haitanensis collected in early harvest (Oct), while the aspartic acid content of N. haitanensis collected in late harvest (Dec) was 1.2 times that of N. haitanensis collected in early harvest (Oct). CONCLUSION The results of enzyme kinetics indicated that NhAAT prefers to catalyze the reaction in the direction of aspartic acid production. Moreover, the trend of NhAAT expression level was consistent with that of aspartic acid content in N. haitanensis in different harvest periods. Our research is helpful to understand the accumulation and regulation of amino acids in N. haitanensis in different habitats and the taste difference of N. haitanensis in different harvest periods.
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Affiliation(s)
- Shuang Li
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhanru Shao
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.
| | - Chang Lu
- Department of Biological Engineering, College of Life Science, Yantai University, Yantai, 264005, P. R. China
| | - Delin Duan
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.
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6
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Drago VN, Dajnowicz S, Parks JM, Blakeley MP, Keen DA, Coquelle N, Weiss KL, Gerlits O, Kovalevsky A, Mueser TC. An N⋯H⋯N low-barrier hydrogen bond preorganizes the catalytic site of aspartate aminotransferase to facilitate the second half-reaction. Chem Sci 2022; 13:10057-10065. [PMID: 36128223 PMCID: PMC9430417 DOI: 10.1039/d2sc02285k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 07/20/2022] [Indexed: 11/21/2022] Open
Abstract
Pyridoxal 5'-phosphate (PLP)-dependent enzymes have been extensively studied for their ability to fine-tune PLP cofactor electronics to promote a wide array of chemistries. Neutron crystallography offers a straightforward approach to studying the electronic states of PLP and the electrostatics of enzyme active sites, responsible for the reaction specificities, by enabling direct visualization of hydrogen atom positions. Here we report a room-temperature joint X-ray/neutron structure of aspartate aminotransferase (AAT) with pyridoxamine 5'-phosphate (PMP), the cofactor product of the first half reaction catalyzed by the enzyme. Between PMP NSB and catalytic Lys258 Nζ amino groups an equally shared deuterium is observed in an apparent low-barrier hydrogen bond (LBHB). Density functional theory calculations were performed to provide further evidence of this LBHB interaction. The structural arrangement and the juxtaposition of PMP and Lys258, facilitated by the LBHB, suggests active site preorganization for the incoming ketoacid substrate that initiates the second half-reaction.
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Affiliation(s)
- Victoria N Drago
- Department of Chemistry and Biochemistry, University of Toledo Toledo OH 43606 USA
- Neutron Scattering Division, Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Steven Dajnowicz
- Department of Chemistry and Biochemistry, University of Toledo Toledo OH 43606 USA
- Neutron Scattering Division, Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Jerry M Parks
- Biosciences Division, Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Matthew P Blakeley
- Large Scale Structures Group, Institut Laue-Langevin 71 Avenue des Martyrs 38000 Grenoble France
| | - David A Keen
- ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus Didcot OX11 0QX UK
| | - Nicolas Coquelle
- Large Scale Structures Group, Institut Laue-Langevin 71 Avenue des Martyrs 38000 Grenoble France
| | - Kevin L Weiss
- Neutron Scattering Division, Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Oksana Gerlits
- Department of Natural Sciences, Tennessee Wesleyan University Athens TN 37303 USA
| | - Andrey Kovalevsky
- Neutron Scattering Division, Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Timothy C Mueser
- Department of Chemistry and Biochemistry, University of Toledo Toledo OH 43606 USA
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7
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Yang J, Li Y, Qiu Q, Wang R, Yan W, Yu Y, Niu L, Pei H, Wei H, Ouyang L, Ye H, Xu D, Wei Y, Chen Q, Chen L. Small Molecules Promote Selective Denaturation and Degradation of Tubulin Heterodimers through a Low-Barrier Hydrogen Bond. J Med Chem 2022; 65:9159-9173. [PMID: 35762925 DOI: 10.1021/acs.jmedchem.2c00379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Here, we report a novel mechanism to selectively degrade target proteins. 3-(3-Phenoxybenzyl)amino-β-carboline (PAC), a tubulin inhibitor, promotes selective degradation of αβ-tubulin heterodimers. Biochemical studies have revealed that PAC specifically denatures tubulin, making it prone to aggregation that predisposes it to ubiquitinylation and then degradation. The degradation is mediated by a single hydrogen bond formed between the pyridine nitrogen of PAC and βGlu198, which is identified as a low-barrier hydrogen bond (LBHB). In contrast, another two tubulin inhibitors that only form normal hydrogen bonds with βGlu198 exhibit no degradation effect. Thus, the LBHB accounts for the degradation. We then screened for compounds capable of forming an LBHB with βGlu198 and demonstrated that BML284, a Wnt signaling activator, also promotes tubulin heterodimer degradation through the LBHB. Our study provided a unique example of LBHB function and identified a novel approach to obtain tubulin degraders.
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Affiliation(s)
- Jianhong Yang
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China
| | - Yong Li
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China
| | - Qiang Qiu
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China
| | - Ruihan Wang
- MOE Key Laboratory of Green Chemistry and Technology, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Wei Yan
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China
| | - Yamei Yu
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China
| | - Lu Niu
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China
| | - Heying Pei
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China
| | - Haoche Wei
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China
| | - Liang Ouyang
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China
| | - Haoyu Ye
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China
| | - Dingguo Xu
- MOE Key Laboratory of Green Chemistry and Technology, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Yuquan Wei
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China
| | - Qiang Chen
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China
| | - Lijuan Chen
- Laboratory of Natural and Targeted Small Molecule Drugs, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China
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Truong DP, Rousseau S, Machala BW, Huddleston JP, Zhu M, Hull KG, Romo D, Raushel FM, Sacchettini JC, Glasner ME. Second-Shell Amino Acid R266 Helps Determine N-Succinylamino Acid Racemase Reaction Specificity in Promiscuous N-Succinylamino Acid Racemase/ o-Succinylbenzoate Synthase Enzymes. Biochemistry 2021; 60:3829-3840. [PMID: 34845903 DOI: 10.1021/acs.biochem.1c00627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Catalytic promiscuity is the coincidental ability to catalyze nonbiological reactions in the same active site as the native biological reaction. Several lines of evidence show that catalytic promiscuity plays a role in the evolution of new enzyme functions. Thus, studying catalytic promiscuity can help identify structural features that predispose an enzyme to evolve new functions. This study identifies a potentially preadaptive residue in a promiscuous N-succinylamino acid racemase/o-succinylbenzoate synthase (NSAR/OSBS) enzyme from Amycolatopsis sp. T-1-60. This enzyme belongs to a branch of the OSBS family which includes many catalytically promiscuous NSAR/OSBS enzymes. R266 is conserved in all members of the NSAR/OSBS subfamily. However, the homologous position is usually hydrophobic in other OSBS subfamilies, whose enzymes lack NSAR activity. The second-shell amino acid R266 is close to the catalytic acid/base K263, but it does not contact the substrate, suggesting that R266 could affect the catalytic mechanism. Mutating R266 to glutamine in Amycolatopsis NSAR/OSBS profoundly reduces NSAR activity but moderately reduces OSBS activity. This is due to a 1000-fold decrease in the rate of proton exchange between the substrate and the general acid/base catalyst K263. This mutation is less deleterious for the OSBS reaction because K263 forms a cation-π interaction with the OSBS substrate and/or the intermediate, rather than acting as a general acid/base catalyst. Together, the data explain how R266 contributes to NSAR reaction specificity and was likely an essential preadaptation for the evolution of NSAR activity.
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Affiliation(s)
- Dat P Truong
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas 77843-2128, United States
| | - Simon Rousseau
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas 77843-2128, United States
| | - Benjamin W Machala
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas 77843-2128, United States
| | - Jamison P Huddleston
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843-3255, United States
| | - Mingzhao Zhu
- Baylor Synthesis and Drug-Lead Discovery Laboratory, Department of Chemistry and Biochemistry, Baylor University, One Bear Place, Waco, Texas 76798-7348, United States
| | - Kenneth G Hull
- Baylor Synthesis and Drug-Lead Discovery Laboratory, Department of Chemistry and Biochemistry, Baylor University, One Bear Place, Waco, Texas 76798-7348, United States
| | - Daniel Romo
- Baylor Synthesis and Drug-Lead Discovery Laboratory, Department of Chemistry and Biochemistry, Baylor University, One Bear Place, Waco, Texas 76798-7348, United States
| | - Frank M Raushel
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas 77843-2128, United States.,Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843-3255, United States
| | - James C Sacchettini
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843-3255, United States
| | - Margaret E Glasner
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas 77843-2128, United States
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9
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Yan S, Qi C, Song W, Xu Q, Gu L, Sun W, Zhang Y. Discovery of GOT1 Inhibitors from a Marine-Derived Aspergillus terreus That Act against Pancreatic Ductal Adenocarcinoma. Mar Drugs 2021; 19:md19110588. [PMID: 34822459 PMCID: PMC8618880 DOI: 10.3390/md19110588] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 10/18/2021] [Accepted: 10/18/2021] [Indexed: 12/12/2022] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is a devastating digestive system carcinoma with high incidence and death rates. PDAC cells are dependent on the Gln metabolism, which can preferentially utilize glutamic oxaloacetate transaminase 1 (GOT1) to maintain the redox homeostasis of cancer cells. Therefore, small molecule inhibitors targeting GOT1 can be used as a new strategy for developing cancer therapies. In this study, 18 butyrolactone derivatives (1–18) were isolated from a marine-derived Aspergillus terreus, and asperteretone B (5), aspulvinone H (AH, 6), and (+)-3′,3′-di-(dimethylallyl)-butyrolactone II (12) were discovered to possess significant GOT1-inhibitory activities in vitro, with IC50 values of (19.16 ± 0.15), (5.91 ± 0.04), and (26.38 ± 0.1) µM, respectively. Significantly, the molecular mechanism of the crystal structure of GOT1–AH was elucidated, wherein AH and the cofactor pyrido-aldehyde 5-phosphate competitively bound to the active sites of GOT1. More importantly, although the crystal structure of GOT1 has been discovered, the complex structure of GOT1 and its inhibitors has never been obtained, and the crystal structure of GOT1–AH is the first reported complex structure of GOT1/inhibitor. Further in vitro biological study indicated that AH could suppress glutamine metabolism, making PDAC cells sensitive to oxidative stress and inhibiting cell proliferation. More significantly, AH exhibited potent in vivo antitumor activity in an SW1990-cell-induced xenograft model. These findings suggest that AH could be considered as a promising lead molecule for the development of anti-PDAC agents.
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Affiliation(s)
- Shan Yan
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; (S.Y.); (C.Q.); (Q.X.); (L.G.)
| | - Changxing Qi
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; (S.Y.); (C.Q.); (Q.X.); (L.G.)
| | - Wei Song
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China;
| | - Qianqian Xu
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; (S.Y.); (C.Q.); (Q.X.); (L.G.)
| | - Lianghu Gu
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; (S.Y.); (C.Q.); (Q.X.); (L.G.)
| | - Weiguang Sun
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; (S.Y.); (C.Q.); (Q.X.); (L.G.)
- Correspondence: (W.S.); (Y.Z.)
| | - Yonghui Zhang
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; (S.Y.); (C.Q.); (Q.X.); (L.G.)
- Correspondence: (W.S.); (Y.Z.)
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10
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York NJ, Lockart MM, Sardar S, Khadka N, Shi W, Stenkamp RE, Zhang J, Kiser PD, Pierce BS. Structure of 3-mercaptopropionic acid dioxygenase with a substrate analog reveals bidentate substrate binding at the iron center. J Biol Chem 2021; 296:100492. [PMID: 33662397 PMCID: PMC8050391 DOI: 10.1016/j.jbc.2021.100492] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/18/2021] [Accepted: 02/26/2021] [Indexed: 12/20/2022] Open
Abstract
Thiol dioxygenases are a subset of nonheme iron oxygenases that catalyze the formation of sulfinic acids from sulfhydryl-containing substrates and dioxygen. Among this class, cysteine dioxygenases (CDOs) and 3-mercaptopropionic acid dioxygenases (3MDOs) are the best characterized, and the mode of substrate binding for CDOs is well understood. However, the manner in which 3-mercaptopropionic acid (3MPA) coordinates to the nonheme iron site in 3MDO remains a matter of debate. A model for bidentate 3MPA coordination at the 3MDO Fe-site has been proposed on the basis of computational docking, whereas steady-state kinetics and EPR spectroscopic measurements suggest a thiolate-only coordination of the substrate. To address this gap in knowledge, we determined the structure of Azobacter vinelandii 3MDO (Av3MDO) in complex with the substrate analog and competitive inhibitor, 3-hydroxypropionic acid (3HPA). The structure together with DFT computational modeling demonstrates that 3HPA and 3MPA associate with iron as chelate complexes with the substrate-carboxylate group forming an additional interaction with Arg168 and the thiol bound at the same position as in CDO. A chloride ligand was bound to iron in the coordination site assigned as the O2-binding site. Supporting HYSCORE spectroscopic experiments were performed on the (3MPA/NO)-bound Av3MDO iron nitrosyl (S = 3/2) site. In combination with spectroscopic simulations and optimized DFT models, this work provides an experimentally verified model of the Av3MDO enzyme-substrate complex, effectively resolving a debate in the literature regarding the preferred substrate-binding denticity. These results elegantly explain the observed 3MDO substrate specificity, but leave unanswered questions regarding the mechanism of substrate-gated reactivity with dioxygen.
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Affiliation(s)
- Nicholas J York
- Department of Chemistry & Biochemistry, University of Alabama, Tuscaloosa, Alabama, USA
| | - Molly M Lockart
- Department of Chemistry & Biochemistry, University of Alabama, Tuscaloosa, Alabama, USA
| | - Sinjinee Sardar
- Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, Texas, USA
| | - Nimesh Khadka
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Wuxian Shi
- National Synchrotron Light Source-II, Brookhaven National Laboratory, Upton, New York, USA
| | - Ronald E Stenkamp
- Departments of Biological Structure and Biochemistry, University of Washington, Seattle, Washington, USA
| | - Jianye Zhang
- Department of Ophthalmology, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - Philip D Kiser
- Department of Ophthalmology, School of Medicine, University of California, Irvine, Irvine, California, USA; Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA; Research Service, VA Long Beach Healthcare System, Long Beach, California, USA.
| | - Brad S Pierce
- Department of Chemistry & Biochemistry, University of Alabama, Tuscaloosa, Alabama, USA.
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11
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Mayengbam S, Chleilat F, Reimer RA. Dietary Vitamin B6 Deficiency Impairs Gut Microbiota and Host and Microbial Metabolites in Rats. Biomedicines 2020; 8:biomedicines8110469. [PMID: 33147768 PMCID: PMC7693528 DOI: 10.3390/biomedicines8110469] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/28/2020] [Accepted: 10/30/2020] [Indexed: 12/15/2022] Open
Abstract
Vitamin B6 plays a crucial role as a cofactor in various enzymatic reactions but bacteria-produced vitamin B6 is not sufficient to meet host requirements. Our objective was to assess the impact of diet-derived vitamin B6 on gut microbiota and host serum metabolomics. Sprague–Dawley rats (n = 47) were fed a control, low B6 (LB6) or high B6 (HB6) diet for six weeks. Serum and cecal samples were collected for biochemical, metabolomics and gut microbiota profiling. There was a significant sex effect for gut microbiota and several metabolic markers. Bodyweight and percent body fat were significantly reduced in LB6 compared to control and HB6 rats. Microbial beta-diversity differed significantly between LB6 and the control and HB6 rats in both sexes. Lachnospiraceae_NK4A136_group and Bacteroides were the primary taxa driving the difference between LB6 and control. There was a significant separation of cecal and serum metabolites of LB6 compared to control and HB6 rats. In the cecum, arginine biosynthesis was impaired, while vitamin B6 metabolism, lysine degradation and nicotinate and nicotinamide metabolism were impaired in serum metabolite profiles. Cecal propionate and butyrate were significantly reduced in LB6 rats irrespective of sex. Host vitamin B6 deficiency but not excess significantly alters gut microbial composition and its metabolites.
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Affiliation(s)
- Shyamchand Mayengbam
- Department of Biochemistry, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada;
| | - Faye Chleilat
- Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada;
| | - Raylene A. Reimer
- Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada;
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
- Correspondence:
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12
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Suplatov D, Sharapova Y, Švedas V. EasyAmber: A comprehensive toolbox to automate the molecular dynamics simulation of proteins. J Bioinform Comput Biol 2020; 18:2040011. [PMID: 32833550 DOI: 10.1142/s0219720020400119] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Conformational plasticity of the functionally important regions and binding sites in protein/enzyme structures is one of the key factors affecting their function and interaction with substrates/ligands. Molecular dynamics (MD) can address the challenge of accounting for protein flexibility by predicting the time-dependent behavior of a molecular system. It has a potential of becoming a particularly important tool in protein engineering and drug discovery, but requires specialized training and skills, what impedes practical use by many investigators. We have developed the easyAmber - a comprehensive set of programs to automate the molecular dynamics routines implemented in the Amber package. The toolbox can address a wide set of tasks in computational biology struggling to account for protein flexibility. The automated workflow includes a complete set of steps from the initial "static" molecular model to the MD "production run": the full-atom model building, optimization/equilibration of the molecular system, classical/conventional and accelerated molecular dynamics simulations. The easyAmber implements advanced MD protocols, but is highly automated and easy-to-operate to attract a broad audience. The toolbox can be used on a personal desktop station equipped with a compatible gaming GPU-accelerator, as well as help to manage huge workloads on a powerful supercomputer. The software provides an opportunity to operate multiple simulations of different proteins at the same time, thus significantly increasing work efficiency. The easyAmber takes the molecular dynamics to the next level in terms of usability for complex processing of large volumes of data, thus supporting the recent trend away from inefficient "static" approaches in biology toward a deeper understanding of the dynamics in protein structures. The software is freely available for download at https://biokinet.belozersky.msu.ru/easyAmber, no login required.
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Affiliation(s)
- Dmitry Suplatov
- Lomonosov Moscow State University, Belozersky Institute of Physico-chemical Biology and Faculty of Bioengineering and Bioinformatics, Leninskiye Gory 1-73, Moscow 119991, Russia
| | - Yana Sharapova
- Lomonosov Moscow State University, Belozersky Institute of Physico-chemical Biology and Faculty of Bioengineering and Bioinformatics, Leninskiye Gory 1-73, Moscow 119991, Russia
| | - Vytas Švedas
- Lomonosov Moscow State University, Belozersky Institute of Physico-chemical Biology and Faculty of Bioengineering and Bioinformatics, Leninskiye Gory 1-73, Moscow 119991, Russia
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13
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Dajnowicz S, Cheng Y, Daemen LL, Weiss KL, Gerlits O, Mueser TC, Kovalevsky A. Substrate Binding Stiffens Aspartate Aminotransferase by Altering the Enzyme Picosecond Vibrational Dynamics. ACS OMEGA 2020; 5:18787-18797. [PMID: 32775880 PMCID: PMC7408236 DOI: 10.1021/acsomega.0c01900] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 07/14/2020] [Indexed: 06/11/2023]
Abstract
Protein dynamics on various time scales from femtoseconds to milliseconds impacts biological function by driving proteins to conformations conducive to ligand binding and creating functional states in enzyme catalysis. Neutron vibrational spectroscopy carried out by measuring inelastic neutron scattering from protein molecules in combination with molecular simulations has the unique ability of detecting and visualizing changes in the picosecond protein vibrational dynamics due to ligand binding. Here we present neutron vibrational spectra of a homodimeric pyridoxal 5'-phosphate-dependent enzyme, aspartate aminotransferase, obtained from the open internal aldimine and closed external aldimine conformational states. We observe that in the external aldimine state the protein structure stiffens relative to the internal aldimine state, indicating rigidified vibrational dynamics on the picosecond time scale in the low-frequency regime of 5-50 cm-1. Our molecular dynamics simulations indicate substantial changes in the picosecond dynamics of the enzyme secondary structure elements upon substrate binding, with the largest contributions from just two helices and the β-sheet.
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Affiliation(s)
- Steven Dajnowicz
- Neutron
Scattering Division, Oak Ridge National
Laboratory, Oak Ridge, Tennessee 37830, United States
- Department
of Chemistry and Biochemistry, University
of Toledo, Toledo, Ohio 43606, United States
| | - Yongqiang Cheng
- Neutron
Scattering Division, Oak Ridge National
Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Luke L. Daemen
- Neutron
Scattering Division, Oak Ridge National
Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Kevin L. Weiss
- Neutron
Scattering Division, Oak Ridge National
Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Oksana Gerlits
- Department
of Natural Sciences, Tennessee Wesleyan
University, Athens, Tennessee 37303, United States
| | - Timothy C. Mueser
- Department
of Chemistry and Biochemistry, University
of Toledo, Toledo, Ohio 43606, United States
| | - Andrey Kovalevsky
- Neutron
Scattering Division, Oak Ridge National
Laboratory, Oak Ridge, Tennessee 37830, United States
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14
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Neutron crystallography of copper amine oxidase reveals keto/enolate interconversion of the quinone cofactor and unusual proton sharing. Proc Natl Acad Sci U S A 2020; 117:10818-10824. [PMID: 32371483 DOI: 10.1073/pnas.1922538117] [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] [Indexed: 11/18/2022] Open
Abstract
Recent advances in neutron crystallographic studies have provided structural bases for quantum behaviors of protons observed in enzymatic reactions. Thus, we resolved the neutron crystal structure of a bacterial copper (Cu) amine oxidase (CAO), which contains a prosthetic Cu ion and a protein-derived redox cofactor, topa quinone (TPQ). We solved hitherto unknown structures of the active site, including a keto/enolate equilibrium of the cofactor with a nonplanar quinone ring, unusual proton sharing between the cofactor and the catalytic base, and metal-induced deprotonation of a histidine residue that coordinates to the Cu. Our findings show a refined active-site structure that gives detailed information on the protonation state of dissociable groups, such as the quinone cofactor, which are critical for catalytic reactions.
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15
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Kędzierski P, Zaczkowska M, Sokalski WA. Extreme Catalytic Power of Ketosteroid Isomerase Related to the Reversal of Proton Dislocations in Hydrogen-Bond Network. J Phys Chem B 2020; 124:3661-3666. [PMID: 32293890 PMCID: PMC7467711 DOI: 10.1021/acs.jpcb.0c01489] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Dynamic
electrostatic catalytic field (DECF) vectors derived from
transition state and reactant wavefunctions for the two-step reaction
occurring within ketosteroid isomerase (KSI) have been calculated
using MP2/aug-cc-pVTZ and lower theory levels to determine the magnitude
of the catalytic effect and the optimal directions of proton transfers
in the KSI hydrogen-bond network. The most surprising and meaningful
finding is that the KSI catalytic activity is enhanced by proton dislocations
proceeding in opposite directions for each of the two consecutive
reaction steps in the same hydrogen network. Such a mechanism allows
an ultrafast switching of the catalytic proton wire environment, possibly
related to the exceptionally high KSI catalytic power.
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Affiliation(s)
- Paweł Kędzierski
- Department of Chemistry, Wrocław University of Science and Technology, Wyb. Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Maria Zaczkowska
- Department of Chemistry, Wrocław University of Science and Technology, Wyb. Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - W Andrzej Sokalski
- Department of Chemistry, Wrocław University of Science and Technology, Wyb. Wyspiańskiego 27, 50-370 Wrocław, Poland
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16
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Mueser TC, Drago V, Kovalevsky A, Dajnowicz S. Pyridoxal 5'-phosphate dependent reactions: Analyzing the mechanism of aspartate aminotransferase. Methods Enzymol 2020; 634:333-359. [PMID: 32093839 DOI: 10.1016/bs.mie.2020.01.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Enzyme catalysis is the primary activity in energy and information metabolism and enzyme cofactors are key to the catalytic ability of most enzymes. Pyridoxal 5'-phosphate (PLP) cofactor, derived from Vitamin B6, is widely distributed in nature and has significant latitude in catalytic diversity. X-ray crystallography has revealed the structures of diverse PLP dependent enzymes from multiple families. But these structures are incomplete, lacking the positions of protons essential for understanding enzymatic mechanisms. Here, we review the diversity of PLP and discuss the use of neutron crystallography and joint X-ray/neutron refinement of Fold Type I aspartate aminotransferase to visualize the positions of protons in both the internal and external aldimine forms. Strategies used to prepare extremely large crystals required for neutron diffraction and the approach to data refinement including the PLP cofactor are discussed. The observed positions of protons, including one located in a previously unknown low-barrier hydrogen bond, have been used to create more accurate models for computational analysis. The results revealed a new mechanism for the transaminase reaction where hyperconjugation is key to reducing the energy barrier which finally provides a clear explanation of the Dunathan alignment.
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Affiliation(s)
- Timothy C Mueser
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH, United States.
| | - Victoria Drago
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH, United States
| | - Andrey Kovalevsky
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Steven Dajnowicz
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH, United States; Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
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17
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Sheng X, Kazemi M, Żądło-Dobrowolska A, Kroutil W, Himo F. Mechanism of Biocatalytic Friedel-Crafts Acylation by Acyltransferase from Pseudomonas protegens. ACS Catal 2020; 10:570-577. [PMID: 31929947 PMCID: PMC6945686 DOI: 10.1021/acscatal.9b04208] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 11/18/2019] [Indexed: 12/22/2022]
Abstract
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Acyltransferases isolated from Pseudomonas
protegens (PpATase) and Pseudomonas fluorescens (PfATase)
have recently been reported to catalyze
the Friedel–Crafts acylation, providing a biological version
of this classical organic reaction. These enzymes catalyze the cofactor-independent
acylation of monoacetylphloroglucinol (MAPG) to diacetylphloroglucinol
(DAPG) and phloroglucinol (PG) and have been demonstrated to have
a wide substrate scope, making them valuable for potential applications
in biocatalysis. Herein, we present a detailed reaction mechanism
of PpATase on the basis of quantum chemical calculations,
employing a large model of the active site. The proposed mechanism
is consistent with available kinetics, mutagenesis, and structural
data. The roles of various active site residues are analyzed. Very
importantly, the Asp137 residue, located more than 10 Å from
the substrate, is predicted to be the proton source for the protonation
of the substrate in the rate-determining step. This key prediction
is corroborated by site-directed mutagenesis experiments. Based on
the current calculations, the regioselectivity of PpATase and its specificity toward non-natural substrates can be rationalized.
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Affiliation(s)
- Xiang Sheng
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
| | - Masoud Kazemi
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
| | - Anna Żądło-Dobrowolska
- Institute of Chemistry, NAWI Graz, BioTechMed Graz, University of Graz, Heinrichstrasse 28, A-8010 Graz, Austria
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
| | - Wolfgang Kroutil
- Institute of Chemistry, NAWI Graz, BioTechMed Graz, University of Graz, Heinrichstrasse 28, A-8010 Graz, Austria
| | - Fahmi Himo
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
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18
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Structural insights into the mechanism of internal aldimine formation and catalytic loop dynamics in an archaeal Group II decarboxylase. J Struct Biol 2019; 208:137-151. [PMID: 31445086 DOI: 10.1016/j.jsb.2019.08.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/15/2019] [Accepted: 08/20/2019] [Indexed: 01/01/2023]
Abstract
Formation of the internal aldimine (LLP) is the first regulatory step that activates pyridoxal 5'-phosphate (PLP) dependent enzymes. The process involves a nucleophilic attack on PLP by an active site Lys residue, followed by proton transfers resulting in a carbinolamine (CBA) intermediate that undergoes dehydration to form the aldimine. Despite a general understanding of the pathway, the structural basis of the mechanistic roles of specific residues in each of these steps is unclear. Here we determined the crystal structure of the LLP form (holo-form) of a Group II PLP-dependent decarboxylase from Methanocaldococcus jannaschii (MjDC) at 1.7 Å resolution. By comparing the crystal structure of MjDC in the LLP form with that of the pyridoxal-P (non-covalently bound aldehyde) form, we demonstrate structural evidence for a water-mediated mechanism of LLP formation. A conserved extended hydrogen-bonding network around PLP coupled to the pyridinyl nitrogen influences activation and catalysis by affecting the electronic configuration of PLP. Furthermore, the two cofactor bound forms revealed open and closed conformations of the catalytic loop (CL) in the absence of a ligand, supporting a hypothesis for a regulatory link between LLP formation and CL dynamics. The evidence suggests that activation of Group II decarboxylases involves a complex interplay of interactions between the electronic states of PLP, the active site micro-environment and CL dynamics.
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19
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Kumar P, Agarwal PK, Waddell MB, Mittag T, Serpersu EH, Cuneo MJ. Low‐Barrier and Canonical Hydrogen Bonds Modulate Activity and Specificity of a Catalytic Triad. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201908535] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Prashasti Kumar
- Graduate School of Genome Science and Technology University of Tennessee Knoxville TN 37996 USA
- Present address: Department of Pharmacological Sciences Icahn School of Medicine at Mount Sinai New York NY 10029 USA
| | - Pratul K. Agarwal
- Department of Biochemistry and Cellular and Molecular Biology University of Tennessee Knoxville TN 37996 USA
| | - M. Brett Waddell
- Molecular Interaction Analysis Shared Resource St. Jude Children's Research Hospital Memphis TN 38105 USA
| | - Tanja Mittag
- Department of Structural Biology St. Jude Children's Research Hospital Memphis TN 38105 USA
| | - Engin H. Serpersu
- Department of Biochemistry and Cellular and Molecular Biology University of Tennessee Knoxville TN 37996 USA
- National Science Foundation Alexandria VA 22314 USA
| | - Matthew J. Cuneo
- Department of Structural Biology St. Jude Children's Research Hospital Memphis TN 38105 USA
- Oak Ridge National Laboratory Oak Ridge TN 37830 USA
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20
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Kumar P, Agarwal PK, Waddell MB, Mittag T, Serpersu EH, Cuneo MJ. Low-Barrier and Canonical Hydrogen Bonds Modulate Activity and Specificity of a Catalytic Triad. Angew Chem Int Ed Engl 2019; 58:16260-16266. [PMID: 31515870 DOI: 10.1002/anie.201908535] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 09/11/2019] [Indexed: 01/14/2023]
Abstract
The position, bonding and dynamics of hydrogen atoms in the catalytic centers of proteins are essential for catalysis. The role of short hydrogen bonds in catalysis has remained highly debated and led to establishment of several distinctive geometrical arrangements of hydrogen atoms vis-à-vis the heavier donor and acceptor counterparts, that is, low-barrier, single-well or short canonical hydrogen bonds. Here we demonstrate how the position of a hydrogen atom in the catalytic triad of an aminoglycoside inactivating enzyme leads to a thirty-fold increase in catalytic turnover. A low-barrier hydrogen bond is present in the enzyme active site for the substrates that are turned over the best, whereas a canonical hydrogen bond is found with the least preferred substrate. This is the first comparison of these hydrogen bonds involving an identical catalytic network, while directly demonstrating how active site electrostatics adapt to the electronic nature of substrates to tune catalysis.
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Affiliation(s)
- Prashasti Kumar
- Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, 37996, USA.,Present address: Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Pratul K Agarwal
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - M Brett Waddell
- Molecular Interaction Analysis Shared Resource, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Tanja Mittag
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Engin H Serpersu
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA.,National Science Foundation, Alexandria, VA, 22314, USA
| | - Matthew J Cuneo
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA.,Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
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21
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Phillips RS, Crocker M, Lin R, Idowu OE, McCannon DK, Lima S. The roles of Ser-36, Asp-132 and Asp-201 in the reaction of Pseudomonas fluorescens Kynureninase. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2019; 1867:722-731. [PMID: 31100408 DOI: 10.1016/j.bbapap.2019.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 05/06/2019] [Accepted: 05/10/2019] [Indexed: 06/09/2023]
Abstract
Kynureninase from Pseudomonas fluorescens (Pfkynase) catalyzes the pyridoxal-5'-phosphate (PLP) dependent hydrolytic cleavage of L-kynurenine to give anthranilate and L-alanine. Asp-132 and Asp-201 are located in the structure near the pyridine NH of the PLP, with Asp-201 forming a hydrogen bond. Mutation of Asp-132 to alanine and glutamate and Asp-201 to glutamate results in reduced catalytic activity with L-kynurenine and β-benzoyl-L-alanine, but not O-benzoyl-l-serine. D132A, D132E D201E and S36A mutant Pfkynases all can form quinonoid and vinylogous amide intermediates with β-benzoyl-L-alanine, similar to wild-type enzyme. D132A, D132E, and D201E Pfkynase react more slowly with β-benzoyl-L-alanine and benzaldehyde to form an aldol product absorbing at 490 nm than wild-type, with D132E reacting the slowest. The 1H NMR spectra of wild-type and D201E Pfkynase are very similar in the low field region from 10 to 18 ppm, but that of D132A Pfkynase is missing a resonance at 13.1 ppm. These results show that these residues modulate the reactivity of the PLP at different stages during the reaction cycle. Ser-36 is located near the expected location of the carbonyl oxygen of the substrate. Mutation of Ser-36 to alanine results in a 230-fold reduction of kcat and 30-fold reduction in kcat/Km with L-kynurenine, but very little effect on the reaction of O-benzoyl-l-serine. Thus, the rate-determining step in the reaction of S36A Pfkynase is the Cβ-Cγ bond cleavage. These results support the hypothesis that Ser-36 together with Tyr-226 is part of an oxyanion hole that polarizes the carbonyl of the substrate in the catalytic mechanism of Pfkynase.
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Affiliation(s)
- Robert S Phillips
- Department of Chemistry, University of Georgia, Athens, GA 30602, United States of America; Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, United States of America.
| | - Mori Crocker
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, United States of America
| | - Richard Lin
- Department of Chemistry, University of Georgia, Athens, GA 30602, United States of America
| | - O Elijah Idowu
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, United States of America
| | - David K McCannon
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, United States of America
| | - Santiago Lima
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, United States of America
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22
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Ni J, Xu G, Dai W, Zhao YL, Ni Y. Hyperconjugation promoted by hydrogen bonding between His98/His241 and a carboxyl group contributes to tyrosine decarboxylase catalysis. Catal Sci Technol 2019. [DOI: 10.1039/c9cy01290g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
This article first demonstrates the utility of the σ → π* hyperconjugation by His98 and His241 in pyridoxal 5′-phosphate-dependent tyrosine decarboxylase.
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Affiliation(s)
- Jie Ni
- Key Laboratory of Industrial Biotechnology
- Ministry of Education
- School of Biotechnology
- Jiangnan University
- Wuxi 214122
| | - Guochao Xu
- Key Laboratory of Industrial Biotechnology
- Ministry of Education
- School of Biotechnology
- Jiangnan University
- Wuxi 214122
| | - Wei Dai
- Key Laboratory of Industrial Biotechnology
- Ministry of Education
- School of Biotechnology
- Jiangnan University
- Wuxi 214122
| | - Yi-Lei Zhao
- State Key Laboratory of Microbial Metabolism
- Joint International Research Laboratory of Metabolic and Developmental Sciences
- MOE-LSB and MOE-LSC
- School of Life Sciences and Biotechnology
- Shanghai Jiao Tong University
| | - Ye Ni
- Key Laboratory of Industrial Biotechnology
- Ministry of Education
- School of Biotechnology
- Jiangnan University
- Wuxi 214122
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23
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Bezsudnova EY, Boyko KM, Nikolaeva AY, Zeifman YS, Rakitina TV, Suplatov DA, Popov VO. Biochemical and structural insights into PLP fold type IV transaminase from Thermobaculum terrenum. Biochimie 2018; 158:130-138. [PMID: 30599183 DOI: 10.1016/j.biochi.2018.12.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 12/27/2018] [Indexed: 10/27/2022]
Abstract
The high catalytic efficiency of enzymes under reaction conditions is one of the main goals in biocatalysis. Despite the dramatic progress in the development of more efficient biocatalysts by protein design, the search for natural enzymes with useful properties remains a promising strategy. The pyridoxal 5'-phosphate (PLP)-dependent transaminases represent a group of industrially important enzymes due to their ability to stereoselectively transfer amino groups between diverse substrates; however, the complex mechanism of substrate recognition and conversion makes the design of transaminases a challenging task. Here we report a detailed structural and kinetic study of thermostable transaminase from the bacterium Thermobaculum terrenum (TaTT) using the methods of enzyme kinetics, X-ray crystallography and molecular modeling. TaTT can convert L-branched-chain and L-aromatic amino acids as well as (R)-(+)-1-phenylethylamine at a high rate and with high enantioselectivity. The structures of TaTT in complex with the cofactor pyridoxal 5'-phosphate covalently bound to enzyme and in complex with its reduced form, pyridoxamine 5'-phosphate, were determined at resolutions of 2.19 Å and 1.5 Å, and deposited in the Protein Data Bank as entries 6GKR and 6Q8E, respectively. TaTT is a fold type IV PLP-dependent enzyme. In terms of structural similarity, the enzyme is close to known branched-chain amino acid aminotransferases, but differences in characteristic sequence motifs in the active site were observed in TaTT compared to canonical branched-chain amino acid aminotransferases, which can explain the improved binding of aromatic amino acids and (R)-(+)-1-phenylethylamine. This study has shown for the first time that high substrate specificity towards both various l-amino acids and (R)-primary amines can be implemented within one pyridoxal 5'-phosphate-dependent active site of fold type IV. These results complement our knowledge of the catalytic diversity of transaminases and indicate the need for further biochemical and bioinformatic studies to understand the sequence-structure-function relationship in these enzymes.
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Affiliation(s)
- Ekaterina Yu Bezsudnova
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, Bld. 2, 119071, Moscow, Russian Federation.
| | - Konstantin M Boyko
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, Bld. 2, 119071, Moscow, Russian Federation; Kurchatov Complex of NBICS-technologies, National Research Centre "Kurchatov Institute", Akad. Kurchatova Sqr 1, 123182, Moscow, Russian Federation
| | - Alena Yu Nikolaeva
- Kurchatov Complex of NBICS-technologies, National Research Centre "Kurchatov Institute", Akad. Kurchatova Sqr 1, 123182, Moscow, Russian Federation
| | - Yulia S Zeifman
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, Bld. 2, 119071, Moscow, Russian Federation; Kurchatov Complex of NBICS-technologies, National Research Centre "Kurchatov Institute", Akad. Kurchatova Sqr 1, 123182, Moscow, Russian Federation
| | - Tatiana V Rakitina
- Kurchatov Complex of NBICS-technologies, National Research Centre "Kurchatov Institute", Akad. Kurchatova Sqr 1, 123182, Moscow, Russian Federation; Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Str. 16/10, 117997, Moscow, Russian Federation
| | - Dmitry A Suplatov
- Lomonosov Moscow State University, Belozersky Institute of Physicochemical Biology, Leninskiye Gory 1-73, Moscow, 119991, Russian Federation
| | - Vladimir O Popov
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, Bld. 2, 119071, Moscow, Russian Federation; Kurchatov Complex of NBICS-technologies, National Research Centre "Kurchatov Institute", Akad. Kurchatova Sqr 1, 123182, Moscow, Russian Federation
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24
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Holt MC, Assar Z, Beheshti Zavareh R, Lin L, Anglin J, Mashadova O, Haldar D, Mullarky E, Kremer DM, Cantley LC, Kimmelman AC, Stein AJ, Lairson LL, Lyssiotis CA. Biochemical Characterization and Structure-Based Mutational Analysis Provide Insight into the Binding and Mechanism of Action of Novel Aspartate Aminotransferase Inhibitors. Biochemistry 2018; 57:6604-6614. [PMID: 30365304 DOI: 10.1021/acs.biochem.8b00914] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Pancreatic cancer cells are characterized by deregulated metabolic programs that facilitate growth and resistance to oxidative stress. Among these programs, pancreatic cancers preferentially utilize a metabolic pathway through the enzyme aspartate aminotransferase 1 [also known as glutamate oxaloacetate transaminase 1 (GOT1)] to support cellular redox homeostasis. As such, small molecule inhibitors that target GOT1 could serve as starting points for the development of new therapies for pancreatic cancer. We ran a high-throughput screen for inhibitors of GOT1 and identified a small molecule, iGOT1-01, with in vitro GOT1 inhibitor activity. Application in pancreatic cancer cells revealed metabolic and growth inhibitory activity reflecting a promiscuous inhibitory profile. We then performed an in silico docking analysis to study inhibitor-GOT1 interactions with iGOT1-01 analogues that possess improved solubility and potency properties. These results suggested that the GOT1 inhibitor competed for binding to the pyridoxal 5-phosphate (PLP) cofactor site of GOT1. To analyze how the GOT1 inhibitor bound to GOT1, a series of GOT1 mutant enzymes that abolished PLP binding were generated. Application of the mutants in X-ray crystallography and thermal shift assays again suggested but were unable to formally conclude that the GOT1 inhibitor bound to the PLP site. Mutational studies revealed the relationship between PLP binding and the thermal stability of GOT1 while highlighting the essential nature of several residues for GOT1 catalytic activity. Insight into the mode of action of GOT1 inhibitors may provide leads to the development of drugs that target redox balance in pancreatic cancer.
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Affiliation(s)
- Melissa C Holt
- Cayman Chemical Company , 1180 East Ellsworth , Ann Arbor , Michigan 48108 , United States
| | - Zahra Assar
- Cayman Chemical Company , 1180 East Ellsworth , Ann Arbor , Michigan 48108 , United States
| | - Reza Beheshti Zavareh
- California Institute for Biomedical Research , 11119 North Torrey Pines Road , La Jolla , California 92037 , United States
| | - Lin Lin
- Department of Molecular and Integrative Physiology , University of Michigan Medical School , Ann Arbor , Michigan 48109 , United States
| | - Justin Anglin
- California Institute for Biomedical Research , 11119 North Torrey Pines Road , La Jolla , California 92037 , United States
| | - Oksana Mashadova
- Meyer Cancer Center, Department of Medicine , Weill Cornell Medical College , New York , New York 10065 , United States
| | - Daniel Haldar
- Department of Systems Biology , Harvard Medical School , Boston , Massachusetts 02215 , United States
| | - Edouard Mullarky
- Meyer Cancer Center, Department of Medicine , Weill Cornell Medical College , New York , New York 10065 , United States
| | - Daniel M Kremer
- Department of Molecular and Integrative Physiology , University of Michigan Medical School , Ann Arbor , Michigan 48109 , United States
| | - Lewis C Cantley
- Meyer Cancer Center, Department of Medicine , Weill Cornell Medical College , New York , New York 10065 , United States
| | - Alec C Kimmelman
- Department of Radiation Oncology, Perlmutter Cancer Center , NYU Langone Medical Center , New York , New York 10016 , United States
| | - Adam J Stein
- Cayman Chemical Company , 1180 East Ellsworth , Ann Arbor , Michigan 48108 , United States
| | - Luke L Lairson
- California Institute for Biomedical Research , 11119 North Torrey Pines Road , La Jolla , California 92037 , United States.,Department of Chemistry , The Scripps Research Institute , 10550 North Torrey Pines Road , La Jolla , California 92037 , United States
| | - Costas A Lyssiotis
- Department of Molecular and Integrative Physiology, Department of Internal Medicine, Division of Gastroenterology, and Rogel Cancer Center , University of Michigan , Ann Arbor , Michigan 48109 , United States
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Dimerization misalignment in human glutamate-oxaloacetate transaminase variants is the primary factor for PLP release. PLoS One 2018; 13:e0203889. [PMID: 30208107 PMCID: PMC6135512 DOI: 10.1371/journal.pone.0203889] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 08/29/2018] [Indexed: 11/30/2022] Open
Abstract
The active form of vitamin B6, pyridoxal 5’-phosphate (PLP), plays an essential role in the catalytic mechanism of various proteins, including human glutamate-oxaloacetate transaminase (hGOT1), an important enzyme in amino acid metabolism. A recent molecular and genetic study showed that the E266K, R267H, and P300L substitutions in aspartate aminotransferase, the Arabidopsis analog of hGOT1, genetically suppress a developmentally arrested Arabidopsis RUS mutant. Furthermore, CD analyses suggested that the variants exist as apo proteins and implicated a possible role of PLP in the regulation of PLP homeostasis and metabolic pathways. In this work, we assessed the stability of PLP bound to hGOT1 for the three variant and wildtype (WT) proteins using a combined 6 μs of molecular dynamics (MD) simulation. For the variants and WT in the holo form, the MD simulations reproduced the “closed-open” transition needed for substrate binding. This conformational transition was associated with the rearrangement of the P15-R32 small domain loop providing substrate access to the R387/R293 binding motif. We also showed that formation of the dimer interface is essential for PLP affinity to the active site. The position of PLP in the WT binding site was stabilized by a unique hydrogen bond network of the phosphate binding cup, which placed the cofactor for formation of the covalent Schiff base linkage with K259 for catalysis. The amino acid substitutions at positions 266, 267, and 300 reduced the structural correlation between PLP and the protein active site and/or integrity of the dimer interface. Principal component analysis and energy decomposition clearly suggested dimer misalignment and dissociation for the three variants tested in our work. The low affinity of PLP in the hGOT1 variants observed in our computational work provided structural rationale for the possible role of vitamin B6 in regulating metabolic pathways.
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Müller N. Iminiumsalz-Strukturen bei der durch Pyridoxalphosphat (Vitamin B6) katalysierten Bildung von Aromastoffen und Fehlaromen im Wein. ZEITSCHRIFT FUR NATURFORSCHUNG SECTION B-A JOURNAL OF CHEMICAL SCIENCES 2018. [DOI: 10.1515/znb-2018-0038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Enzymes that use pyridoxal phosphate (PLP, Vitamin B6) as cofactor constitute a ubiquitous class of biocatalysts. A variety of PLP-dependant enzymes mainly involved in biochemical pathways concerning amino acid metabolism are found in all forms of life. These enzymes also play an important role in wine production, as well in grape growing as in enological processes. The formation of pleasant aroma compounds often runs with participation of pyridoxal-dependant enzymes. But these are also brought into context with the formation of off-odors, especially from sulfur compounds (i.e. sulfur containing amino acids cysteine, methionine). The versatility of PLP-dependant bioreactions arises from its ability to covalently bind the substrate and then to function as an electrophilic catalyst, thereby stabilizing different types of carbanionic reaction intermediates, containing iminium salt structures. This article summarizes the influence of PLP on sensorically important aroma compounds in wine growing and wine processing.
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Fesko K, Suplatov D, Švedas V. Bioinformatic analysis of the fold type I PLP-dependent enzymes reveals determinants of reaction specificity in l-threonine aldolase from Aeromonas jandaei. FEBS Open Bio 2018; 8:1013-1028. [PMID: 29928580 PMCID: PMC5986058 DOI: 10.1002/2211-5463.12441] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 04/27/2018] [Indexed: 01/19/2023] Open
Abstract
Understanding the role of specific amino acid residues in the molecular mechanism of a protein's function is one of the most challenging problems in modern biology. A systematic bioinformatic analysis of protein families and superfamilies can help in the study of structure–function relationships and in the design of improved variants of enzymes/proteins, but represents a methodological challenge. The pyridoxal‐5′‐phosphate (PLP)‐dependent enzymes are catalytically diverse and include the aspartate aminotransferase superfamily which implements a common structural framework known as type fold I. In this work, the recently developed bioinformatic online methods Mustguseal and Zebra were used to collect and study a large representative set of the aspartate aminotransferase superfamily with high structural, but low sequence similarity to l‐threonine aldolase from Aeromonas jandaei (LTAaj), in order to identify conserved positions that provide general properties in the superfamily, and to reveal family‐specific positions (FSPs) responsible for functional diversity. The roles of the identified residues in the catalytic mechanism and reaction specificity of LTAaj were then studied by experimental site‐directed mutagenesis and molecular modelling. It was shown that FSPs determine reaction specificity by coordinating the PLP cofactor in the enzyme's active centre, thus influencing its activation and the tautomeric equilibrium of the intermediates, which can be used as hotspots to modulate the protein's functional properties. Mutagenesis at the selected FSPs in LTAaj led to a reduction in a native catalytic activity and increased the rate of promiscuous reactions. The results provide insight into the structural basis of catalytic promiscuity of the PLP‐dependent enzymes and demonstrate the potential of bioinformatic analysis in studying structure–function relationship in protein superfamilies.
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Affiliation(s)
- Kateryna Fesko
- Institute of Organic Chemistry Graz University of Technology Austria
| | - Dmitry Suplatov
- Belozersky Institute of Physicochemical Biology Lomonosov Moscow State University Russia
| | - Vytas Švedas
- Belozersky Institute of Physicochemical Biology Lomonosov Moscow State University Russia
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29
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Rojas-Ortega E, Aguirre-López B, Reyes-Vivas H, González-Andrade M, Campero-Basaldúa JC, Pardo JP, González A. Saccharomyces cerevisiae Differential Functionalization of Presumed ScALT1 and ScALT2 Alanine Transaminases Has Been Driven by Diversification of Pyridoxal Phosphate Interactions. Front Microbiol 2018; 9:944. [PMID: 29867852 PMCID: PMC5960717 DOI: 10.3389/fmicb.2018.00944] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 04/23/2018] [Indexed: 12/16/2022] Open
Abstract
Saccharomyces cerevisiae arose from an interspecies hybridization (allopolyploidiza-tion), followed by Whole Genome Duplication. Diversification analysis of ScAlt1/ScAlt2 indicated that while ScAlt1 is an alanine transaminase, ScAlt2 lost this activity, constituting an example in which one of the members of the gene pair lacks the apparent ancestral physiological role. This paper analyzes structural organization and pyridoxal phosphate (PLP) binding properties of ScAlt1 and ScAlt2 indicating functional diversification could have determined loss of ScAlt2 alanine transaminase activity and thus its role in alanine metabolism. It was found that ScAlt1 and ScAlt2 are dimeric enzymes harboring 67% identity and intact conservation of the catalytic residues, with very similar structures. However, tertiary structure analysis indicated that ScAlt2 has a more open conformation than that of ScAlt1 so that under physiological conditions, while PLP interaction with ScAlt1 allows the formation of two tautomeric PLP isomers (enolimine and ketoenamine) ScAlt2 preferentially forms the ketoenamine PLP tautomer, indicating a modified polarity of the active sites which affect the interaction of PLP with these proteins, that could result in lack of alanine transaminase activity in ScAlt2. The fact that ScAlt2 forms a catalytically active Schiff base with PLP and its position in an independent clade in "sensu strictu" yeasts suggests this protein has a yet undiscovered physiological function.
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Affiliation(s)
- Erendira Rojas-Ortega
- Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Beatriz Aguirre-López
- Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Horacio Reyes-Vivas
- Laboratorio de Bioquímica-Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City, Mexico
| | - Martín González-Andrade
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Jose C Campero-Basaldúa
- Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Juan P Pardo
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Alicia González
- Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
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30
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Marcinkowski D, Fik MA, Łuczak T, Kubicki M, Patroniak V. New Mn(II) complexes with benzoxazole-based ligands: Synthesis, structure and their electrochemical behavior. Polyhedron 2018. [DOI: 10.1016/j.poly.2017.11.039] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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31
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Alapour S, Zamisa SJ, Silva JRA, Alves CN, Omondi B, Ramjugernath D, Koorbanally NA. Investigations into the flexibility of the 3D structure and rigid backbone of quinoline by fluorine addition to enhance its blue emission. CrystEngComm 2018. [DOI: 10.1039/c8ce00094h] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Addition of fluorine to the quinoline structure was found to decrease its intermolecular interactions and influence its 3D structure.
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Affiliation(s)
- S. Alapour
- School of Chemistry and Physics
- University of KwaZulu-Natal
- Durban
- South Africa
| | - S. J. Zamisa
- School of Chemistry and Physics
- University of KwaZulu-Natal
- Durban
- South Africa
| | - J. R. A. Silva
- Laboratório de Planejamento e Desenvolvimento de Fármacos, Instituto de Ciências Exatas e Naturais
- Universidade Federal do Pará
- Belém
- Brazil
| | - C. N. Alves
- Laboratório de Planejamento e Desenvolvimento de Fármacos, Instituto de Ciências Exatas e Naturais
- Universidade Federal do Pará
- Belém
- Brazil
| | - B. Omondi
- School of Chemistry and Physics
- University of KwaZulu-Natal
- Durban
- South Africa
| | - D. Ramjugernath
- School of Chemical Engineering
- University of KwaZulu-Natal
- Durban 4041
- South Africa
| | - N. A. Koorbanally
- School of Chemistry and Physics
- University of KwaZulu-Natal
- Durban
- South Africa
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32
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Yang L, Niu J, Zhan Y, Xu Y, Sun R, Ge J. Fluorescence Responses of the Protonation and Deprotonation Processes between Phenolate and Phenol within Rosamine. CHINESE J CHEM 2017. [DOI: 10.1002/cjoc.201700534] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Ling Yang
- College of Chemistry, Chemical Engineering and Material Science; Soochow University, 199 Ren'Ai Road; Suzhou Jiangsu 215123 China
| | - Jinyun Niu
- School of Radiation Medicine and Protection; Medical College of Soochow University; Suzhou Jiangsu 215123 China
| | - Yanhua Zhan
- College of Chemistry, Chemical Engineering and Material Science; Soochow University, 199 Ren'Ai Road; Suzhou Jiangsu 215123 China
| | - Yujie Xu
- School of Radiation Medicine and Protection; Medical College of Soochow University; Suzhou Jiangsu 215123 China
| | - Ru Sun
- College of Chemistry, Chemical Engineering and Material Science; Soochow University, 199 Ren'Ai Road; Suzhou Jiangsu 215123 China
| | - Jianfeng Ge
- College of Chemistry, Chemical Engineering and Material Science; Soochow University, 199 Ren'Ai Road; Suzhou Jiangsu 215123 China
- Jiangsu Key Laboratory of Medical Optics, Suzhou Institute of Biomedical, Engineering and Technology; Chinese Academy of Sciences; Suzhou 215163 China
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Direct visualization of critical hydrogen atoms in a pyridoxal 5'-phosphate enzyme. Nat Commun 2017; 8:955. [PMID: 29038582 PMCID: PMC5643538 DOI: 10.1038/s41467-017-01060-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 08/15/2017] [Indexed: 11/13/2022] Open
Abstract
Enzymes dependent on pyridoxal 5′-phosphate (PLP, the active form of vitamin B6) perform a myriad of diverse chemical transformations. They promote various reactions by modulating the electronic states of PLP through weak interactions in the active site. Neutron crystallography has the unique ability of visualizing the nuclear positions of hydrogen atoms in macromolecules. Here we present a room-temperature neutron structure of a homodimeric PLP-dependent enzyme, aspartate aminotransferase, which was reacted in situ with α-methylaspartate. In one monomer, the PLP remained as an internal aldimine with a deprotonated Schiff base. In the second monomer, the external aldimine formed with the substrate analog. We observe a deuterium equidistant between the Schiff base and the C-terminal carboxylate of the substrate, a position indicative of a low-barrier hydrogen bond. Quantum chemical calculations and a low-pH room-temperature X-ray structure provide insight into the physical phenomena that control the electronic modulation in aspartate aminotransferase. Pyridoxal 5’-phosphate (PLP) is a ubiquitous co factor for diverse enzymes, among them aspartate aminotransferase. Here the authors use neutron crystallography, which allows the visualization of the positions of hydrogen atoms, and computation to characterize the catalytic mechanism of the enzyme.
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Radiation damage at the active site of human alanine:glyoxylate aminotransferase reveals that the cofactor position is finely tuned during catalysis. Sci Rep 2017; 7:11704. [PMID: 28916765 PMCID: PMC5601474 DOI: 10.1038/s41598-017-11948-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 08/24/2017] [Indexed: 11/08/2022] Open
Abstract
The alanine:glyoxylate aminotransferase (AGT), a hepatocyte-specific pyridoxal-5'-phosphate (PLP) dependent enzyme, transaminates L-alanine and glyoxylate to glycine and pyruvate, thus detoxifying glyoxylate and preventing pathological oxalate precipitation in tissues. In the widely accepted catalytic mechanism of the aminotransferase family, the lysine binding to PLP acts as a catalyst in the stepwise 1,3-proton transfer, interconverting the external aldimine to ketimine. This step requires protonation by a conserved aspartate of the pyridine nitrogen of PLP to enhance its ability to stabilize the carbanionic intermediate. The aspartate residue is also responsible for a significant geometrical distortion of the internal aldimine, crucial for catalysis. We present the structure of human AGT in which complete X-ray photoreduction of the Schiff base has occurred. This result, together with two crystal structures of the conserved aspartate pathogenic variant (D183N) and the molecular modeling of the transaldimination step, led us to propose that an interplay of opposite forces, which we named spring mechanism, finely tunes PLP geometry during catalysis and is essential to move the external aldimine in the correct position in order for the 1,3-proton transfer to occur.
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