1
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Hupfeld E, Schlee S, Wurm JP, Rajendran C, Yehorova D, Vos E, Ravindra Raju D, Kamerlin SCL, Sprangers R, Sterner R. Conformational Modulation of a Mobile Loop Controls Catalysis in the (βα) 8-Barrel Enzyme of Histidine Biosynthesis HisF. JACS AU 2024; 4:3258-3276. [PMID: 39211614 PMCID: PMC11350729 DOI: 10.1021/jacsau.4c00558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2024] [Revised: 08/07/2024] [Accepted: 08/07/2024] [Indexed: 09/04/2024]
Abstract
The overall significance of loop motions for enzymatic activity is generally accepted. However, it has largely remained unclear whether and how such motions can control different steps of catalysis. We have studied this problem on the example of the mobile active site β1α1-loop (loop1) of the (βα)8-barrel enzyme HisF, which is the cyclase subunit of imidazole glycerol phosphate synthase. Loop1 variants containing single mutations of conserved amino acids showed drastically reduced rates for the turnover of the substrates N'-[(5'-phosphoribulosyl) formimino]-5-aminoimidazole-4-carboxamide ribonucleotide (PrFAR) and ammonia to the products imidazole glycerol phosphate (ImGP) and 5-aminoimidazole-4-carboxamide-ribotide (AICAR). A comprehensive mechanistic analysis including stopped-flow kinetics, X-ray crystallography, NMR spectroscopy, and molecular dynamics simulations detected three conformations of loop1 (open, detached, closed) whose populations differed between wild-type HisF and functionally affected loop1 variants. Transient stopped-flow kinetic experiments demonstrated that wt-HisF binds PrFAR by an induced-fit mechanism whereas catalytically impaired loop1 variants bind PrFAR by a simple two-state mechanism. Our findings suggest that PrFAR-induced formation of the closed conformation of loop1 brings active site residues in a productive orientation for chemical turnover, which we show to be the rate-limiting step of HisF catalysis. After the cyclase reaction, the closed loop conformation is destabilized, which favors the formation of detached and open conformations and hence facilitates the release of the products ImGP and AICAR. Our data demonstrate how different conformations of active site loops contribute to different catalytic steps, a finding that is presumably of broad relevance for the reaction mechanisms of (βα)8-barrel enzymes and beyond.
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Affiliation(s)
- Enrico Hupfeld
- Institute
of Biophysics and Physical Biochemistry, Regensburg Center for Biochemistry, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Sandra Schlee
- Institute
of Biophysics and Physical Biochemistry, Regensburg Center for Biochemistry, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Jan Philip Wurm
- Institute
of Biophysics and Physical Biochemistry, Regensburg Center for Biochemistry, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Chitra Rajendran
- Institute
of Biophysics and Physical Biochemistry, Regensburg Center for Biochemistry, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Dariia Yehorova
- School
of Chemistry and Biochemistry, Georgia Institute
of Technology, 901 Atlantic Drive NW, Atlanta, Georgia 30318, United States
| | - Eva Vos
- School
of Chemistry and Biochemistry, Georgia Institute
of Technology, 901 Atlantic Drive NW, Atlanta, Georgia 30318, United States
| | - Dinesh Ravindra Raju
- School
of Chemistry and Biochemistry, Georgia Institute
of Technology, 901 Atlantic Drive NW, Atlanta, Georgia 30318, United States
| | - Shina Caroline Lynn Kamerlin
- School
of Chemistry and Biochemistry, Georgia Institute
of Technology, 901 Atlantic Drive NW, Atlanta, Georgia 30318, United States
| | - Remco Sprangers
- Institute
of Biophysics and Physical Biochemistry, Regensburg Center for Biochemistry, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Reinhard Sterner
- Institute
of Biophysics and Physical Biochemistry, Regensburg Center for Biochemistry, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
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2
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Jiang J, Keniya MV, Puri A, Zhan X, Cheng J, Wang H, Lin G, Lee YK, Jaber N, Hassoun Y, Shor E, Shi Z, Lee SH, Xu M, Perlin DS, Dai W. Structural and Biophysical Dynamics of Fungal Plasma Membrane Proteins and Implications for Echinocandin Action in Candida glabrata. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.29.596243. [PMID: 38854035 PMCID: PMC11160696 DOI: 10.1101/2024.05.29.596243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Fungal plasma membrane proteins represent key therapeutic targets for antifungal agents, yet their structure and spatial distribution in the native context remain poorly characterized. Herein, we employ an integrative multimodal approach to elucidate the structural and functional organization of plasma membrane protein complexes in Candida glabrata , focusing on prominent and essential membrane proteins, the polysaccharide synthase β-(1,3)-glucan synthase (GS) and the proton pump Pma1. Cryo-electron tomography (cryo-ET) and live cell imaging reveal that GS and Pma1 are heterogeneously distributed into distinct plasma membrane microdomains. Treatment with caspofungin, an echinocandin antifungal that targets GS, alters the plasma membrane and disrupts the native distribution of GS and Pma1. Based on these findings, we propose a model for echinocandin action that considers how drug interactions with the plasma membrane environment lead to inhibition of GS. Our work underscores the importance of interrogating the structural and dynamic characteristics of fungal plasma membrane proteins in situ to understand function and facilitate precisely targeted development of novel antifungal therapies.
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3
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Zinovjev K, Guénon P, Ramos-Guzmán CA, Ruiz-Pernía JJ, Laage D, Tuñón I. Activation and friction in enzymatic loop opening and closing dynamics. Nat Commun 2024; 15:2490. [PMID: 38509080 PMCID: PMC10955111 DOI: 10.1038/s41467-024-46723-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 03/04/2024] [Indexed: 03/22/2024] Open
Abstract
Protein loop dynamics have recently been recognized as central to enzymatic activity, specificity and stability. However, the factors controlling loop opening and closing kinetics have remained elusive. Here, we combine molecular dynamics simulations with string-method determination of complex reaction coordinates to elucidate the molecular mechanism and rate-limiting step for WPD-loop dynamics in the PTP1B enzyme. While protein conformational dynamics is often represented as diffusive motion hindered by solvent viscosity and internal friction, we demonstrate that loop opening and closing is activated. It is governed by torsional rearrangement around a single loop peptide group and by significant friction caused by backbone adjustments, which can dynamically trap the loop. Considering both torsional barrier and time-dependent friction, our calculated rate constants exhibit very good agreement with experimental measurements, reproducing the change in loop opening kinetics between proteins. Furthermore, we demonstrate the applicability of our results to other enzymatic loops, including the M20 DHFR loop, thereby offering prospects for loop engineering potentially leading to enhanced designs.
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Affiliation(s)
- Kirill Zinovjev
- Departamento de Química Física, Universidad de Valencia, 46100, Burjasot, Spain
| | - Paul Guénon
- Departamento de Química Física, Universidad de Valencia, 46100, Burjasot, Spain
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France
| | - Carlos A Ramos-Guzmán
- Departamento de Química Física, Universidad de Valencia, 46100, Burjasot, Spain
- Instituto de Materiales Avanzados, Universidad Jaume I, 12071, Castelló, Spain
| | | | - Damien Laage
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France
| | - Iñaki Tuñón
- Departamento de Química Física, Universidad de Valencia, 46100, Burjasot, Spain.
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France.
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4
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Crean RM, Corbella M, Calixto AR, Hengge AC, Kamerlin SCL. Sequence - dynamics - function relationships in protein tyrosine phosphatases. QRB DISCOVERY 2024; 5:e4. [PMID: 38689874 PMCID: PMC11058592 DOI: 10.1017/qrd.2024.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 09/20/2023] [Accepted: 10/24/2023] [Indexed: 05/02/2024] Open
Abstract
Protein tyrosine phosphatases (PTPs) are crucial regulators of cellular signaling. Their activity is regulated by the motion of a conserved loop, the WPD-loop, from a catalytically inactive open to a catalytically active closed conformation. WPD-loop motion optimally positions a catalytically critical residue into the active site, and is directly linked to the turnover number of these enzymes. Crystal structures of chimeric PTPs constructed by grafting parts of the WPD-loop sequence of PTP1B onto the scaffold of YopH showed WPD-loops in a wide-open conformation never previously observed in either parent enzyme. This wide-open conformation has, however, been observed upon binding of small molecule inhibitors to other PTPs, suggesting the potential of targeting it for drug discovery efforts. Here, we have performed simulations of both enzymes and show that there are negligible energetic differences in the chemical step of catalysis, but significant differences in the dynamical properties of the WPD-loop. Detailed interaction network analysis provides insight into the molecular basis for this population shift to a wide-open conformation. Taken together, our study provides insight into the links between loop dynamics and chemistry in these YopH variants specifically, and how WPD-loop dynamic can be engineered through modification of the internal protein interaction network.
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Affiliation(s)
- Rory M. Crean
- Department of Chemistry – BMC, Uppsala University, Uppsala, Sweden
| | - Marina Corbella
- Department of Chemistry – BMC, Uppsala University, Uppsala, Sweden
- Departament de Química Inorgànica i Orgànica (Secció de Química Orgànica) & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Barcelona, Spain
| | - Ana R. Calixto
- Department of Chemistry – BMC, Uppsala University, Uppsala, Sweden
- LAQV, REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Porto, Portugal
| | - Alvan C. Hengge
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, USA
| | - Shina C. L. Kamerlin
- Department of Chemistry – BMC, Uppsala University, Uppsala, Sweden
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
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5
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Oanca G, van der Ent F, Åqvist J. Efficient Empirical Valence Bond Simulations with GROMACS. J Chem Theory Comput 2023; 19:6037-6045. [PMID: 37623818 PMCID: PMC10500987 DOI: 10.1021/acs.jctc.3c00714] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Indexed: 08/26/2023]
Abstract
We describe a protocol to perform empirical valence bond (EVB) simulations using GROMACS software. EVB is a fast and reliable method that allows one to determine the reaction free-energy profiles in complex systems, such as enzymes, by employing classical force fields to represent a chemical reaction. Therefore, running EVB simulations is basically as fast as any classical molecular dynamics simulation, and the method uses standard free-energy calculations to map the free-energy change along a given reaction path. To exemplify and validate our EVB implementation, we replicated two cases of our earlier enzyme simulations. One of these addresses the decomposition of the activation free energy into its enthalpic and entropic components, and the other is focused on calculating the overall catalytic effect of the enzyme compared to the same reaction in water. These two examples give virtually identical results to those obtained with programs that were specifically designed for EVB simulations and show that the GROMACS implementation is robust and can be used for very large systems.
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Affiliation(s)
- Gabriel Oanca
- Department of Cell and Molecular Biology,
Biomedical Center, Uppsala University, Uppsala SE-751 24, Sweden
| | - Florian van der Ent
- Department of Cell and Molecular Biology,
Biomedical Center, Uppsala University, Uppsala SE-751 24, Sweden
| | - Johan Åqvist
- Department of Cell and Molecular Biology,
Biomedical Center, Uppsala University, Uppsala SE-751 24, Sweden
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6
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Corbella M, Pinto GP, Kamerlin SCL. Loop dynamics and the evolution of enzyme activity. Nat Rev Chem 2023; 7:536-547. [PMID: 37225920 DOI: 10.1038/s41570-023-00495-w] [Citation(s) in RCA: 29] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2023] [Indexed: 05/26/2023]
Abstract
In the early 2000s, Tawfik presented his 'New View' on enzyme evolution, highlighting the role of conformational plasticity in expanding the functional diversity of limited repertoires of sequences. This view is gaining increasing traction with increasing evidence of the importance of conformational dynamics in both natural and laboratory evolution of enzymes. The past years have seen several elegant examples of harnessing conformational (particularly loop) dynamics to successfully manipulate protein function. This Review revisits flexible loops as critical participants in regulating enzyme activity. We showcase several systems of particular interest: triosephosphate isomerase barrel proteins, protein tyrosine phosphatases and β-lactamases, while briefly discussing other systems in which loop dynamics are important for selectivity and turnover. We then discuss the implications for engineering, presenting examples of successful loop manipulation in either improving catalytic efficiency, or changing selectivity completely. Overall, it is becoming clearer that mimicking nature by manipulating the conformational dynamics of key protein loops is a powerful method of tailoring enzyme activity, without needing to target active-site residues.
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Affiliation(s)
- Marina Corbella
- Department of Chemistry, Uppsala University, Uppsala, Sweden
| | - Gaspar P Pinto
- Department of Chemistry, Uppsala University, Uppsala, Sweden
- Cortex Discovery GmbH, Regensburg, Germany
| | - Shina C L Kamerlin
- Department of Chemistry, Uppsala University, Uppsala, Sweden.
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA.
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7
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Hegazy R, Cordara G, Wierenga RK, Richard JP. The Role of Asn11 in Catalysis by Triosephosphate Isomerase. Biochemistry 2023; 62:1794-1806. [PMID: 37162263 PMCID: PMC10249627 DOI: 10.1021/acs.biochem.3c00133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 04/14/2023] [Indexed: 05/11/2023]
Abstract
Four catalytic amino acids at triosephosphate isomerase (TIM) are highly conserved: N11, K13, H95, and E167. Asparagine 11 is the last of these to be characterized in mutagenesis studies. The ND2 side chain atom of N11 is hydrogen bonded to the O-1 hydroxyl of enzyme-bound dihydroxyacetone phosphate (DHAP), and it sits in an extended chain of hydrogen-bonded side chains that includes T75' from the second subunit. The N11A variants of wild-type TIM from Trypanosoma brucei brucei (TbbTIM) and Leishmania mexicana (LmTIM) undergo dissociation from the dimer to monomer under our assay conditions. Values of Kas = 8 × 103 and 1 × 106 M-1, respectively, were determined for the conversion of monomeric N11A TbbTIM and LmTIM into their homodimers. The N11A substitution at the variant of LmTIM previously stabilized by the E65Q substitution gives the N11A/E65Q variant that is stable to dissociation under our assay conditions. The X-ray crystal structure of N11A/E65Q LmTIM shows an active site that is essentially superimposable on that for wild-type TbbTIM, which also has a glutamine at position 65. A comparison of the kinetic parameters for E65Q LmTIM and N11A/E65Q LmTIM-catalyzed reactions of (R)-glyceraldehyde 3-phosphate (GAP) and (DHAP) shows that the N11A substitution results in a (13-14)-fold decrease in kcat/Km for substrate isomerization and a similar decrease in kcat for DHAP but only a 2-fold decrease in kcat for GAP.
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Affiliation(s)
- Rania Hegazy
- Department
of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, United
States
| | - Gabriele Cordara
- Biocenter
Oulu, University of Oulu, P.O. Box 5000, FIN-90014 Oulu, Finland
| | - Rik K. Wierenga
- Faculty of
Biochemistry and Molecular Medicine, University
of Oulu, P.O. Box 5400, FIN-90014 Oulu, Finland
| | - John P. Richard
- Department
of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, United
States
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8
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Brickel S, Demkiv AO, Crean RM, Pinto GP, Kamerlin SCL. Q-RepEx: A Python pipeline to increase the sampling of empirical valence bond simulations. J Mol Graph Model 2023; 119:108402. [PMID: 36610324 DOI: 10.1016/j.jmgm.2022.108402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/17/2022] [Accepted: 12/26/2022] [Indexed: 12/31/2022]
Abstract
The exploration of chemical systems occurs on complex energy landscapes. Comprehensively sampling rugged energy landscapes with many local minima is a common problem for molecular dynamics simulations. These multiple local minima trap the dynamic system, preventing efficient sampling. This is a particular challenge for large biochemical systems with many degrees of freedom. Replica exchange molecular dynamics (REMD) is an approach that accelerates the exploration of the conformational space of a system, and thus can be used to enhance the sampling of complex biomolecular processes. In parallel, the empirical valence bond (EVB) approach is a powerful approach for modeling chemical reactivity in biomolecular systems. Here, we present an open-source Python-based tool that interfaces with the Q simulation package, and increases the sampling efficiency of the EVB free energy perturbation/umbrella sampling approach by means of REMD. This approach, Q-RepEx, both decreases the computational cost of the associated REMD-EVB simulations, and opens the door to more efficient studies of biochemical reactivity in systems with significant conformational fluctuations along the chemical reaction coordinate.
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Affiliation(s)
- Sebastian Brickel
- Department of Chemistry - BMC, Uppsala University, BMC Box 576, S-751 23, Uppsala, Sweden
| | - Andrey O Demkiv
- Department of Chemistry - BMC, Uppsala University, BMC Box 576, S-751 23, Uppsala, Sweden
| | - Rory M Crean
- Department of Chemistry - BMC, Uppsala University, BMC Box 576, S-751 23, Uppsala, Sweden
| | - Gaspar P Pinto
- Department of Chemistry - BMC, Uppsala University, BMC Box 576, S-751 23, Uppsala, Sweden
| | - Shina Caroline Lynn Kamerlin
- Department of Chemistry - BMC, Uppsala University, BMC Box 576, S-751 23, Uppsala, Sweden; School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, GA, 30332-0400, USA.
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9
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In Silico Discovery of Anticancer Peptides from Sanghuang. Int J Mol Sci 2022; 23:ijms232213682. [PMID: 36430160 PMCID: PMC9693127 DOI: 10.3390/ijms232213682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 10/24/2022] [Accepted: 11/04/2022] [Indexed: 11/10/2022] Open
Abstract
Anticancer peptide (ACP) is a short peptide with less than 50 amino acids that has been discovered in a variety of foods. It has been demonstrated that traditional Chinese medicine or food can help treat cancer in some cases, which suggests that ACP may be one of the therapeutic ingredients. Studies on the anti-cancer properties of Sanghuangporus sanghuang have concentrated on polysaccharides, flavonoids, triterpenoids, etc. The function of peptides has not received much attention. The purpose of this study is to use computer mining techniques to search for potential anticancer peptides from 62 proteins of Sanghuang. We used mACPpred to perform sequence scans after theoretical trypsin hydrolysis and discovered nine fragments with an anticancer probability of over 0.60. The study used AlphaFold 2 to perform structural modeling of the first three ACPs discovered, which had blast results from the Cancer PPD database. Using reverse docking technology, we found the target proteins and interacting residues of two ACPs with an unknown mechanism. Reverse docking results predicted the binding modes of the ACPs and their target protein. In addition, we determined the active part of ACPs by quantum chemical calculation. Our study provides a framework for the future discovery of functional peptides from foods. The ACPs discovered have the potential to be used as drugs in oncology clinical treatment after further research.
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10
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Allen PW, Cook JA, Colquhoun AN, Sorin EJ, Tapavicza E, Schwans JP. Energetically unfavorable protein angles: Exploration of a conserved dihedral angle in triosephosphate isomerase. Biopolymers 2022; 113:e23525. [DOI: 10.1002/bip.23525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 08/22/2022] [Accepted: 08/25/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Patrick W. Allen
- Department of Chemistry and Biochemistry California State University Long Beach Long Beach California USA
| | - Jordan A. Cook
- Department of Chemistry and Biochemistry California State University Long Beach Long Beach California USA
| | - Anh N. Colquhoun
- Department of Chemistry and Biochemistry California State University Long Beach Long Beach California USA
| | - Eric J. Sorin
- Department of Chemistry and Biochemistry California State University Long Beach Long Beach California USA
| | - Enrico Tapavicza
- Department of Chemistry and Biochemistry California State University Long Beach Long Beach California USA
| | - Jason P. Schwans
- Department of Chemistry and Biochemistry California State University Long Beach Long Beach California USA
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11
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Kelpšas V, Caldararu O, Blakeley MP, Coquelle N, Wierenga RK, Ryde U, von Wachenfeldt C, Oksanen E. Neutron structures of Leishmania mexicana triosephosphate isomerase in complex with reaction-intermediate mimics shed light on the proton-shuttling steps. IUCRJ 2021; 8:633-643. [PMID: 34258011 PMCID: PMC8256706 DOI: 10.1107/s2052252521004619] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 04/30/2021] [Indexed: 06/13/2023]
Abstract
Triosephosphate isomerase (TIM) is a key enzyme in glycolysis that catalyses the interconversion of glyceraldehyde 3-phosphate and dihydroxy-acetone phosphate. This simple reaction involves the shuttling of protons mediated by protolysable side chains. The catalytic power of TIM is thought to stem from its ability to facilitate the deprotonation of a carbon next to a carbonyl group to generate an enediolate intermediate. The enediolate intermediate is believed to be mimicked by the inhibitor 2-phosphoglycolate (PGA) and the subsequent enediol intermediate by phosphoglycolohydroxamate (PGH). Here, neutron structures of Leishmania mexicana TIM have been determined with both inhibitors, and joint neutron/X-ray refinement followed by quantum refinement has been performed. The structures show that in the PGA complex the postulated general base Glu167 is protonated, while in the PGH complex it remains deprotonated. The deuteron is clearly localized on Glu167 in the PGA-TIM structure, suggesting an asymmetric hydrogen bond instead of a low-barrier hydrogen bond. The full picture of the active-site protonation states allowed an investigation of the reaction mechanism using density-functional theory calculations.
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Affiliation(s)
- Vinardas Kelpšas
- Department of Biology, Lund University, Sölvegatan 35, 223 62 Lund, Sweden
| | - Octav Caldararu
- Department of Chemistry, Lund University, 221 00 Lund, Sweden
| | - Matthew P. Blakeley
- Large-Scale Structures Group, Institut Laue–Langevin, 71 Avenue des Martyrs, 38042 Grenoble, France
| | - Nicolas Coquelle
- Large-Scale Structures Group, Institut Laue–Langevin, 71 Avenue des Martyrs, 38042 Grenoble, France
| | - Rikkert K. Wierenga
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Pentti Kaiteran katu 1, 90570 Oulu, Finland
| | - Ulf Ryde
- Department of Chemistry, Lund University, 221 00 Lund, Sweden
| | | | - Esko Oksanen
- European Spallation Source Consortium ESS ERIC, Odarslövsvägen 113, 224 84 Lund, Sweden
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12
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Identification of phosphosites that alter protein thermal stability. Nat Methods 2021; 18:760-762. [PMID: 34140699 PMCID: PMC8783534 DOI: 10.1038/s41592-021-01178-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 05/05/2021] [Indexed: 02/03/2023]
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13
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Richard JP, Cristobal JR, Amyes TL. Linear Free Energy Relationships for Enzymatic Reactions: Fresh Insight from a Venerable Probe. Acc Chem Res 2021; 54:2532-2542. [PMID: 33939414 PMCID: PMC8157535 DOI: 10.1021/acs.accounts.1c00147] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
![]()
Linear free energy relationships (LFERs) for substituent effects on reactions that
proceed through similar transition states provide insight into transition state
structures. A classical approach to the analysis of LFERs showed that differences in the
slopes of Brønsted correlations for addition of substituted alkyl alcohols to
ring-substituted 1-phenylethyl carbocations and to the β-galactopyranosyl
carbocation intermediate of reactions catalyzed by β-galactosidase provide
evidence that the enzyme catalyst modifies the curvature of the energy surface at the
saddle point for the transition state for nucleophile addition. We have worked to
generalize the use of LFERs in the determination of enzyme mechanisms. The defining
property of enzyme catalysts is their specificity for binding the transition state with
a much higher affinity than the substrate. Triosephosphate isomerase (TIM), orotidine
5′-monophosphate decarboxylase (OMPDC), and glycerol 3-phosphate dehydrogenase
(GPDH) show effective catalysis of reactions of phosphorylated substrates and strong
phosphite dianion activation of reactions of phosphodianion truncated substrates, with
rate constants kcat/Km
(M–1 s–1) and
kcat/KdKHPi
(M–2 s–1), respectively. Good linear logarithmic
correlations, with a slope of 1.1, between these kinetic parameters determined for
reactions catalyzed by five or more variant forms of each catalyst are observed, where
the protein substitutions are mainly at side chains which function to stabilize the cage
complex between the enzyme and substrate. This shows that the enzyme-catalyzed reactions
of a whole substrate and substrate pieces proceed through transition states of similar
structures. It provides support for the proposal that the dianion binding energy of
whole phosphodianion substrates and of phosphite dianion is used to drive the conversion
of these protein catalysts from flexible and entropically rich ground states to stiff
and catalytically active Michaelis complexes that show the same activity toward
catalysis of the reactions of whole and phosphodianion truncated substrates. There is a
good linear correlation, with a slope of 0.73, between values of the dissociation
constants log Ki for release of the transition state analog
phosphoglycolate (PGA) trianion and log
kcat/Km for isomerization of
GAP for wild-type and variants of TIM. This correlation shows that the substituted amino
acid side chains act to stabilize the complex between TIM and the PGA trianion and that
ca. 70% of this stabilization is observed at the transition state for
substrate deprotonation. The correlation provides evidence that these side chains
function to enhance the basicity of the E165 side chain of TIM, which deprotonates the
bound carbon acid substrate. There is a good linear correlation, with a slope of 0.74,
between the values of ΔG‡ and
ΔG° determined by electron valence bond (EVB) calculations
to model deprotonation of dihydroxyacetone phosphate (DHAP) in water and when bound to
wild-type and variant forms of TIM to form the enediolate reaction intermediate. This
correlation provides evidence that the stabilizing interactions of the transition state
for TIM-catalyzed deprotonation of DHAP are optimized by placement of amino acid side
chains in positions that provide for the maximum stabilization of the charged reaction
intermediate, relative to the neutral substrate.
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Affiliation(s)
- John P. Richard
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, United States
| | - Judith R. Cristobal
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, United States
| | - Tina L. Amyes
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, United States
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14
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Silverstein TP. How enzymes harness highly unfavorable proton transfer reactions. Protein Sci 2021; 30:735-744. [PMID: 33554401 DOI: 10.1002/pro.4037] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/01/2021] [Accepted: 02/05/2021] [Indexed: 11/12/2022]
Abstract
Acid-base reactions that are exceedingly unfavorable under standard conditions can be catalytically important at enzyme active sites. For example, in triose phosphate isomerase, a glutamate side chain (nominal pKa ≈ 4 in solution) can in fact deprotonate a CH group that is vicinal to a carbonyl (pKa ≈ 18 in solution). This is true because of three distinct interactions: (a) ground state pKa shifts due to environment polarity and electrostatics; (b) dramatic increases in effective molarity due to optimization of proximity and orientation; and (c) transition state pKa shifts due to binding interactions and the formation of strong low barrier hydrogen bonds. In this report, we review the literature showing that the sum of these three effects supplies more than enough free energy to push forward proton transfer reactions that under standard conditions are exceedingly nonspontaneous and slow.
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15
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Dynamic 3D proteomes reveal protein functional alterations at high resolution in situ. Cell 2020; 184:545-559.e22. [PMID: 33357446 PMCID: PMC7836100 DOI: 10.1016/j.cell.2020.12.021] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 08/21/2020] [Accepted: 12/11/2020] [Indexed: 02/02/2023]
Abstract
Biological processes are regulated by intermolecular interactions and chemical modifications that do not affect protein levels, thus escaping detection in classical proteomic screens. We demonstrate here that a global protein structural readout based on limited proteolysis-mass spectrometry (LiP-MS) detects many such functional alterations, simultaneously and in situ, in bacteria undergoing nutrient adaptation and in yeast responding to acute stress. The structural readout, visualized as structural barcodes, captured enzyme activity changes, phosphorylation, protein aggregation, and complex formation, with the resolution of individual regulated functional sites such as binding and active sites. Comparison with prior knowledge, including other ‘omics data, showed that LiP-MS detects many known functional alterations within well-studied pathways. It suggested distinct metabolite-protein interactions and enabled identification of a fructose-1,6-bisphosphate-based regulatory mechanism of glucose uptake in E. coli. The structural readout dramatically increases classical proteomics coverage, generates mechanistic hypotheses, and paves the way for in situ structural systems biology. Dynamic structural proteomic screens detect functional changes at high resolution Detect enzyme activity, phosphorylation, and molecular interactions in situ Generate new molecular hypotheses and increase functional proteomics coverage Enabled discovery of a regulatory mechanism of glucose uptake in E. coli
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16
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Romero JM. Triosephosphate isomerase deficiency: Effect of F240L mutation on enzyme structure. Arch Biochem Biophys 2020; 689:108473. [PMID: 32585311 DOI: 10.1016/j.abb.2020.108473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/16/2020] [Accepted: 06/17/2020] [Indexed: 11/29/2022]
Abstract
Eleven missense mutations have been describe in human triosephosphate isomerase (TPI), affecting its catalytic function. Several of these mutations generate triosephosphate isomerase deficiency, the consequences of which can in some cases be lethal. The missense F240L mutation was found in a Hungarian patient showing symptoms of chronic hemolytic anemia and neuromuscular dysfunction. In vitro studies using a recombinant version of this mutant showed that it affects kinetic parameters, thermal stability and dimeric stability. Using X-ray crystal structures, the present paper describes how this mutation affected the flexibility of catalytic residues K13 and part of the (β/α) 8-barrel fold facing the dimeric interface in the TPI.
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Affiliation(s)
- Jorge Miguel Romero
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Universidad Nacional de Córdoba - Consejo Nacional de Investigaciones Científicas y Técnicas (UNC-CONICET), Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre s/n, X5000HUA, Córdoba, Pabellón Argentina Ala Oeste, Argentina.
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17
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The role of ligand-gated conformational changes in enzyme catalysis. Biochem Soc Trans 2020; 47:1449-1460. [PMID: 31657438 PMCID: PMC6824834 DOI: 10.1042/bst20190298] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 10/03/2019] [Accepted: 10/07/2019] [Indexed: 11/17/2022]
Abstract
Structural and biochemical studies on diverse enzymes have highlighted the importance of ligand-gated conformational changes in enzyme catalysis, where the intrinsic binding energy of the common phosphoryl group of their substrates is used to drive energetically unfavorable conformational changes in catalytic loops, from inactive open to catalytically competent closed conformations. However, computational studies have historically been unable to capture the activating role of these conformational changes. Here, we discuss recent experimental and computational studies, which can remarkably pinpoint the role of ligand-gated conformational changes in enzyme catalysis, even when not modeling the loop dynamics explicitly. Finally, through our joint analyses of these data, we demonstrate how the synergy between theory and experiment is crucial for furthering our understanding of enzyme catalysis.
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18
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Liao Q. Enhanced sampling and free energy calculations for protein simulations. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 170:177-213. [PMID: 32145945 DOI: 10.1016/bs.pmbts.2020.01.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Molecular dynamics simulation is a powerful computational technique to study biomolecular systems, which complements experiments by providing insights into the structural dynamics relevant to biological functions at atomic scale. It can also be used to calculate the free energy landscapes of the conformational transitions to better understand the functions of the biomolecules. However, the sampling of biomolecular configurations is limited by the free energy barriers that need to be overcome, leading to considerable gaps between the timescales reached by MD simulation and those governing biological processes. To address this issue, many enhanced sampling methodologies have been developed to increase the sampling efficiency of molecular dynamics simulations and free energy calculations. Usually, enhanced sampling algorithms can be classified into methods based on collective variables (CV-based) and approaches which do not require predefined CVs (CV-free). In this chapter, the theoretical basis of free energy estimation is briefly reviewed first, followed by the reviews of the most common CV-based and CV-free methods including the presentation of some examples and recent developments. Finally, the combination of different enhanced sampling methods is discussed.
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Affiliation(s)
- Qinghua Liao
- Science for Life Laboratory, Department of Chemistry-BMC, Uppsala University, Uppsala, Sweden.
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19
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Kulkarni YS, Amyes TL, Richard JP, Kamerlin SCL. Uncovering the Role of Key Active-Site Side Chains in Catalysis: An Extended Brønsted Relationship for Substrate Deprotonation Catalyzed by Wild-Type and Variants of Triosephosphate Isomerase. J Am Chem Soc 2019; 141:16139-16150. [PMID: 31508957 PMCID: PMC7032883 DOI: 10.1021/jacs.9b08713] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
We report results of detailed empirical valence bond simulations that model the effect of several amino acid substitutions on the thermodynamic (ΔG°) and kinetic activation (ΔG⧧) barriers to deprotonation of dihydroxyacetone phosphate (DHAP) and d-glyceraldehyde 3-phosphate (GAP) bound to wild-type triosephosphate isomerase (TIM), as well as to the K12G, E97A, E97D, E97Q, K12G/E97A, I170A, L230A, I170A/L230A, and P166A variants of this enzyme. The EVB simulations model the observed effect of the P166A mutation on protein structure. The E97A, E97Q, and E97D mutations of the conserved E97 side chain result in ≤1.0 kcal mol-1 decreases in the activation barrier for substrate deprotonation. The agreement between experimental and computed activation barriers is within ±1 kcal mol-1, with a strong linear correlation between ΔG⧧ and ΔG° for all 11 variants, with slopes β = 0.73 (R2 = 0.994) and β = 0.74 (R2 = 0.995) for the deprotonation of DHAP and GAP, respectively. These Brønsted-type correlations show that the amino acid side chains examined in this study function to reduce the standard-state Gibbs free energy of reaction for deprotonation of the weak α-carbonyl carbon acid substrate to form the enediolate phosphate reaction intermediate. TIM utilizes the cationic side chain of K12 to provide direct electrostatic stabilization of the enolate oxyanion, and the nonpolar side chains of P166, I170, and L230 are utilized for the construction of an active-site cavity that provides optimal stabilization of the enediolate phosphate intermediate relative to the carbon acid substrate.
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Affiliation(s)
- Yashraj S Kulkarni
- Science for Life Laboratory, Department of Chemistry - BMC , Uppsala University, BMC , Box 576, S-751 23 Uppsala , Sweden
| | - Tina L Amyes
- Department of Chemistry , University at Buffalo, SUNY , Buffalo , New York 14260-3000 , United States
| | - John P Richard
- Department of Chemistry , University at Buffalo, SUNY , Buffalo , New York 14260-3000 , United States
| | - Shina C L Kamerlin
- Science for Life Laboratory, Department of Chemistry - BMC , Uppsala University, BMC , Box 576, S-751 23 Uppsala , Sweden
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20
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Deng H, Dyer RB, Callender R. Active-Site Glu165 Activation in Triosephosphate Isomerase and Its Deprotonation Kinetics. J Phys Chem B 2019; 123:4230-4241. [PMID: 31013084 DOI: 10.1021/acs.jpcb.9b02981] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Triosephosphate isomerase (TIM) catalyzes the interconversion between dihydroxyacetone phosphate (DHAP) and d-glyceraldehyde 3-phosphate (GAP) via an enediol(ate) intermediate. The active-site residue Glu165 serves as the catalytic base during catalysis. It abstracts a proton from C1 carbon of DHAP to form the reaction intermediate and donates a proton to C2 carbon of the intermediate to form product GAP. Our difference Fourier transform infrared spectroscopy studies on the yeast TIM (YeTIM)/phosphate complex revealed a C═O stretch band at 1706 cm-1 from the protonated Glu165 carboxyl group at pH 7.5, indicating that the p Ka of the catalytic base is increased by >3.0 pH units upon phosphate binding, and that the Glu165 carboxyl environment in the complex is still hydrophilic in spite of the increased p Ka. Hence, the results show that the binding of the phosphodianion group is part of the activation mechanism which involves the p Ka elevation of the catalytic base Glu165. The deprotonation kinetics of Glu165 in the μs to ms time range were determined via infrared (IR) T-jump studies on the YeTIM/phosphate and ("heavy enzyme") [U-13C,-15N]YeTIM/phosphate complexes. The slower deprotonation kinetics in the ms time scale is due to phosphate dissociation modulated by the loop motion, which slows down by enzyme mass increase to show a normal heavy enzyme kinetic isotope effect (KIE) ∼1.2 (i.e., slower rate in the heavy enzyme). The faster deprotonation kinetics in the tens of μs time scale is assigned to temperature-induced p Ka decrease, while phosphate is still bound, and it shows an inverse heavy enzyme KIE ∼0.89 (faster rate in the heavy enzyme). The IR static and T-jump spectroscopy provides atomic-level resolution of the catalytic mechanism because of its ability to directly observe the bond breaking/forming process.
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Affiliation(s)
- Hua Deng
- Department of Biochemistry , Albert Einstein College of Medicine , Bronx, New York 10461 , United States
| | - R Brian Dyer
- Department of Chemistry , Emory University , Atlanta , Georgia 30322 , United States
| | - Robert Callender
- Department of Biochemistry , Albert Einstein College of Medicine , Bronx, New York 10461 , United States
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21
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Bertolani SJ, Siegel JB. A new benchmark illustrates that integration of geometric constraints inferred from enzyme reaction chemistry can increase enzyme active site modeling accuracy. PLoS One 2019; 14:e0214126. [PMID: 30947258 PMCID: PMC6448891 DOI: 10.1371/journal.pone.0214126] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 03/07/2019] [Indexed: 01/06/2023] Open
Abstract
Enzymes play a critical role in a wide array of industrial, medical, and research applications and with the recent explosion of genomic sequencing, we now have sequences for millions of enzymes for which there is no known structure. In order to utilize modern computational design tools for constructing inhibitors or engineering novel catalysts, the ability to accurately model enzymes is critical. A popular approach for modeling enzymes are comparative modeling techniques which can often accurately predict the global structural features. However, achieving atomic accuracy of an active site remains a challenge and is an issue when trying to utilize the molecular details for designing inhibitors or enhanced catalysts. Here we explore integrating knowledge about the required geometric orientation of conserved catalytic residues into the comparative modeling process in order to improve modeling accuracy. In order to investigate the utility of adding this information, we first carefully construct a benchmark set of reference structures to use. Consistent with previous findings, our benchmark demonstrates that the geometry between catalytic residues across an enzyme family is conserved and does not tend to deviate by more than 0.5Å. We then find that by integrating these geometric constraints during modeling, we can double the number of atomic level accuracy models (<1Å RMSD to the crystal structure ligand) within our benchmarking dataset, even for targets with templates as low as 20-30% sequence identity. Catalytic residues within an enzyme family are highly conserved and can often be readily identified through comparative sequence analysis to a known structure within the enzyme family. Therefore utilizing this readily available information has the potential to significantly improve drug design and enzyme engineering efforts for which there is no known structure for the enzyme of interest.
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Affiliation(s)
- Steve J. Bertolani
- Department of Chemistry, University of California Davis, Davis, California, United States of America
| | - Justin B. Siegel
- Department of Chemistry, University of California Davis, Davis, California, United States of America
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, California, United States of America
- Genome Center, University of California Davis, Davis, California, United States of America
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22
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Liao Q, Kulkarni Y, Sengupta U, Petrović D, Mulholland AJ, van der Kamp MW, Strodel B, Kamerlin SCL. Loop Motion in Triosephosphate Isomerase Is Not a Simple Open and Shut Case. J Am Chem Soc 2018; 140:15889-15903. [PMID: 30362343 DOI: 10.1021/jacs.8b09378] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Conformational changes are crucial for the catalytic action of many enzymes. A prototypical and well-studied example is loop opening and closure in triosephosphate isomerase (TIM), which is thought to determine the rate of catalytic turnover in many circumstances. Specifically, TIM loop 6 "grips" the phosphodianion of the substrate and, together with a change in loop 7, sets up the TIM active site for efficient catalysis. Crystal structures of TIM typically show an open or a closed conformation of loop 6, with the tip of the loop moving ∼7 Å between conformations. Many studies have interpreted this motion as a two-state, rigid-body transition. Here, we use extensive molecular dynamics simulations, with both conventional and enhanced sampling techniques, to analyze loop motion in apo and substrate-bound TIM in detail, using five crystal structures of the dimeric TIM from Saccharomyces cerevisiae. We find that loop 6 is highly flexible and samples multiple conformational states. Empirical valence bond simulations of the first reaction step show that slight displacements away from the fully closed-loop conformation can be sufficient to abolish most of the catalytic activity; full closure is required for efficient reaction. The conformational change of the loops in TIM is thus not a simple "open and shut" case and is crucial for its catalytic action. Our detailed analysis of loop motion in a highly efficient enzyme highlights the complexity of loop conformational changes and their role in biological catalysis.
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Affiliation(s)
- Qinghua Liao
- Department of Chemistry - BMC , Uppsala University , BMC Box 576, 751 23 Uppsala , Sweden
| | - Yashraj Kulkarni
- Department of Chemistry - BMC , Uppsala University , BMC Box 576, 751 23 Uppsala , Sweden
| | - Ushnish Sengupta
- Institute of Complex Systems: Structural Biochemistry (ICS-6) , Forschungszentrum Jülich , 52425 Jülich , Germany.,German Research School for Simulation Sciences , RWTH Aachen University , 52062 Aachen , Germany
| | - Dušan Petrović
- Department of Chemistry - BMC , Uppsala University , BMC Box 576, 751 23 Uppsala , Sweden.,Institute of Complex Systems: Structural Biochemistry (ICS-6) , Forschungszentrum Jülich , 52425 Jülich , Germany
| | - Adrian J Mulholland
- Centre for Computational Chemistry, School of Chemistry , University of Bristol , Cantock's Close , BS8 1TS Bristol , United Kingdom
| | - Marc W van der Kamp
- Centre for Computational Chemistry, School of Chemistry , University of Bristol , Cantock's Close , BS8 1TS Bristol , United Kingdom.,School of Biochemistry , University of Bristol , University Walk , BS8 1TD Bristol , United Kingdom
| | - Birgit Strodel
- Institute of Complex Systems: Structural Biochemistry (ICS-6) , Forschungszentrum Jülich , 52425 Jülich , Germany.,Institute of Theoretical and Computational Chemistry , Heinrich Heine University Düsseldorf , 40225 Düsseldorf , Germany
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23
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Evolutionary repurposing of a sulfatase: A new Michaelis complex leads to efficient transition state charge offset. Proc Natl Acad Sci U S A 2018; 115:E7293-E7302. [PMID: 30012610 DOI: 10.1073/pnas.1607817115] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The recruitment and evolutionary optimization of promiscuous enzymes is key to the rapid adaptation of organisms to changing environments. Our understanding of the precise mechanisms underlying enzyme repurposing is, however, limited: What are the active-site features that enable the molecular recognition of multiple substrates with contrasting catalytic requirements? To gain insights into the molecular determinants of adaptation in promiscuous enzymes, we performed the laboratory evolution of an arylsulfatase to improve its initially weak phenylphosphonate hydrolase activity. The evolutionary trajectory led to a 100,000-fold enhancement of phenylphosphonate hydrolysis, while the native sulfate and promiscuous phosphate mono- and diester hydrolyses were only marginally affected (≤50-fold). Structural, kinetic, and in silico characterizations of the evolutionary intermediates revealed that two key mutations, T50A and M72V, locally reshaped the active site, improving access to the catalytic machinery for the phosphonate. Measured transition state (TS) charge changes along the trajectory suggest the creation of a new Michaelis complex (E•S, enzyme-substrate), with enhanced leaving group stabilization in the TS for the promiscuous phosphonate (βleavinggroup from -1.08 to -0.42). Rather than altering the catalytic machinery, evolutionary repurposing was achieved by fine-tuning the molecular recognition of the phosphonate in the Michaelis complex, and by extension, also in the TS. This molecular scenario constitutes a mechanistic alternative to adaptation solely based on enzyme flexibility and conformational selection. Instead, rapid functional transitions between distinct chemical reactions rely on the high reactivity of permissive active-site architectures that allow multiple substrate binding modes.
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24
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Zhai X, Reinhardt CJ, Malabanan MM, Amyes TL, Richard JP. Enzyme Architecture: Amino Acid Side-Chains That Function To Optimize the Basicity of the Active Site Glutamate of Triosephosphate Isomerase. J Am Chem Soc 2018; 140:8277-8286. [PMID: 29862813 PMCID: PMC6037162 DOI: 10.1021/jacs.8b04367] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
![]()
We report pH rate profiles for kcat and Km for the
isomerization reaction
of glyceraldehyde 3-phosphate catalyzed by wildtype triosephosphate
isomerase (TIM) from three organisms and by ten mutants of TIM; and,
for Ki for inhibition of this reaction
by phosphoglycolate trianion (I3–). The pH profiles for Ki show
that the binding of I3– to TIM (E) to form EH·I3– is accompanied by
uptake of a proton by the carboxylate side-chain of E165, whose function
is to abstract a proton from substrate. The complexes for several
mutants exist mainly as E–·I3– at high pH, in which cases the pH profiles define the pKa for deprotonation of EH·I3–. The linear
free energy correlation, with slope of 0.73 (r2 = 0.96), between kcat/Km for TIM-catalyzed isomerization and the disassociation
constant of PGA trianion for TIM shows that EH·I3– and the
transition state are stabilized by similar interactions with the protein
catalyst. Values of pKa = 10–10.5
were estimated for deprotonation of EH·I3– for wildtype TIM.
This pKa decreases to as low as 6.3 for
the severely crippled Y208F mutant. There is a correlation between
the effect of several mutations on kcat/Km and on pKa for EH·I3–. The results support a model where the strong basicity of
E165 at the complex to the enediolate reaction intermediate is promoted
by side-chains from Y208 and S211, which serve to clamp loop 6 over
the substrate; I170, which assists in the creation of a hydrophobic
environment for E165; and P166, which functions in driving the carboxylate
side-chain of E165 toward enzyme-bound substrate.
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Affiliation(s)
- Xiang Zhai
- Department of Chemistry , University at Buffalo, SUNY , Buffalo , New York 14260-3000 United States
| | - Christopher J Reinhardt
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 S Mathews Avenue , Urbana , Illinois 61801 , United States
| | - M Merced Malabanan
- Department of Biochemistry , Vanderbilt University , 842 Robinson Research Building , Nashville , Tennessee 37205 , United States
| | - Tina L Amyes
- Department of Chemistry , University at Buffalo, SUNY , Buffalo , New York 14260-3000 United States
| | - John P Richard
- Department of Chemistry , University at Buffalo, SUNY , Buffalo , New York 14260-3000 United States
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25
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Deng H, Vedad J, Desamero RZB, Callender R. Difference FTIR Studies of Substrate Distribution in Triosephosphate Isomerase. J Phys Chem B 2017; 121:10036-10045. [PMID: 28990791 PMCID: PMC5687254 DOI: 10.1021/acs.jpcb.7b08114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Triosephosphate isomerase (TIM) catalyzes the interconversion between dihydroxyacetone phosphate (DHAP) and d-glyceraldehyde 3-phosphate (GAP), via an enediol(ate) intermediate. Determination of substrate population distribution in the TIM/substrate reaction mixture at equilibrium and characterization of the substrate-enzyme interactions in the Michaelis complex are ongoing efforts toward the understanding of the TIM reaction mechanism. By using isotope-edited difference Fourier transform infrared studies with unlabeled and 13C-labeled substrates at specific carbon(s), we are able to show that in the reaction mixture at equilibrium the keto DHAP is the dominant species and the populations of aldehyde GAP and enediol(ate) are very low, consistent with the results from previous X-ray structural and 13C NMR studies. Furthermore, within the DHAP side of the Michaelis complex, there is a set of conformational substates that can be characterized by the different C2═O stretch frequencies. The C2═O frequency differences reflect the different degree of the C2═O bond polarization due to hydrogen bonding from active site residues. The C2═O bond polarization has been considered as an important component for substrate activation within the Michaelis complex. We have found that in the enzyme-substrate reaction mixture with TIM from different organisms the number of substates and their population distribution within the DHAP side of the Michaelis complex may be different. These discoveries provide a rare opportunity to probe the interconversion dynamics of these DHAP substates and form the bases for the future studies to determine if the TIM-catalyzed reaction follows a simple linear reaction pathway, as previously believed, or follows parallel reaction pathways, as suggested in another enzyme system that also shows a set of substates in the Michaelis complex.
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Affiliation(s)
- Hua Deng
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - Jayson Vedad
- Programs in Chemistry and Biochemistry, CUNY Graduate Center and Department of Chemistry, York College of CUNY, Jamaica, New York 11451, United States
| | - Ruel Z. B. Desamero
- Programs in Chemistry and Biochemistry, CUNY Graduate Center and Department of Chemistry, York College of CUNY, Jamaica, New York 11451, United States
| | - Robert Callender
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
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26
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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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27
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Kulkarni Y, Liao Q, Petrović D, Krüger DM, Strodel B, Amyes TL, Richard JP, Kamerlin SCL. Enzyme Architecture: Modeling the Operation of a Hydrophobic Clamp in Catalysis by Triosephosphate Isomerase. J Am Chem Soc 2017; 139:10514-10525. [PMID: 28683550 PMCID: PMC5543394 DOI: 10.1021/jacs.7b05576] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Indexed: 12/22/2022]
Abstract
Triosephosphate isomerase (TIM) is a proficient catalyst of the reversible isomerization of dihydroxyacetone phosphate (DHAP) to d-glyceraldehyde phosphate (GAP), via general base catalysis by E165. Historically, this enzyme has been an extremely important model system for understanding the fundamentals of biological catalysis. TIM is activated through an energetically demanding conformational change, which helps position the side chains of two key hydrophobic residues (I170 and L230), over the carboxylate side chain of E165. This is critical both for creating a hydrophobic pocket for the catalytic base and for maintaining correct active site architecture. Truncation of these residues to alanine causes significant falloffs in TIM's catalytic activity, but experiments have failed to provide a full description of the action of this clamp in promoting substrate deprotonation. We perform here detailed empirical valence bond calculations of the TIM-catalyzed deprotonation of DHAP and GAP by both wild-type TIM and its I170A, L230A, and I170A/L230A mutants, obtaining exceptional quantitative agreement with experiment. Our calculations provide a linear free energy relationship, with slope 0.8, between the activation barriers and Gibbs free energies for these TIM-catalyzed reactions. We conclude that these clamping side chains minimize the Gibbs free energy for substrate deprotonation, and that the effects on reaction driving force are largely expressed at the transition state for proton transfer. Our combined analysis of previous experimental and current computational results allows us to provide an overview of the breakdown of ground-state and transition state effects in enzyme catalysis in unprecedented detail, providing a molecular description of the operation of a hydrophobic clamp in triosephosphate isomerase.
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Affiliation(s)
- Yashraj
S. Kulkarni
- Science
for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, Uppsala S-751 24, Sweden
| | - Qinghua Liao
- Science
for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, Uppsala S-751 24, Sweden
| | - Dušan Petrović
- Institute
of Complex Systems: Structural Biochemistry, Forschungszentrum Jülich, Jülich 52425, Germany
| | - Dennis M. Krüger
- Science
for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, Uppsala S-751 24, Sweden
| | - Birgit Strodel
- Institute
of Complex Systems: Structural Biochemistry, Forschungszentrum Jülich, Jülich 52425, Germany
- Institute
of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, Düsseldorf 40225, Germany
| | - Tina L. Amyes
- Department
of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, United States
| | - John P. Richard
- Department
of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, United States
| | - Shina C. L. Kamerlin
- Science
for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, Uppsala S-751 24, Sweden
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28
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Abstract
The main problem for enzymes from psychrophilic species, which need to work near the freezing point of liquid water, is the exponential decay of reaction rates as the temperature is decreased. Cold-adapted enzymes have solved this problem by shifting the activation enthalpy-entropy balance for the catalyzed reaction compared to those of their mesophilic orthologs. To understand the structural basis of this universal feature, it is necessary to examine pairs of such orthologous enzymes, with known three-dimensional structures, at the microscopic level. Here, we use molecular dynamics free energy calculations in combination with the empirical valence bond method to evaluate the temperature dependence of the activation free energy for differently adapted triosephosphate isomerases. The results show that the enzyme from the psychrophilic bacterium Vibrio marinus indeed displays the characteristic shift in enthalpy-entropy balance, compared to that of the yeast ortholog. The origin of this effect is found to be located in a few surface-exposed protein loops that show differential mobilities in the two enzymes. Key mutations render these loops more mobile in the cold-adapted triosephosphate isomerase, which explains both the reduced activation enthalpy contribution from the protein surface and the lower thermostability.
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Affiliation(s)
- Johan Åqvist
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University , Box 596, SE-751 24 Uppsala, Sweden
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29
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The self-inhibitory nature of metabolic networks and its alleviation through compartmentalization. Nat Commun 2017; 8:16018. [PMID: 28691704 PMCID: PMC5508129 DOI: 10.1038/ncomms16018] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Accepted: 05/23/2017] [Indexed: 01/03/2023] Open
Abstract
Metabolites can inhibit the enzymes that generate them. To explore the general nature of metabolic self-inhibition, we surveyed enzymological data accrued from a century of experimentation and generated a genome-scale enzyme-inhibition network. Enzyme inhibition is often driven by essential metabolites, affects the majority of biochemical processes, and is executed by a structured network whose topological organization is reflecting chemical similarities that exist between metabolites. Most inhibitory interactions are competitive, emerge in the close neighbourhood of the inhibited enzymes, and result from structural similarities between substrate and inhibitors. Structural constraints also explain one-third of allosteric inhibitors, a finding rationalized by crystallographic analysis of allosterically inhibited L-lactate dehydrogenase. Our findings suggest that the primary cause of metabolic enzyme inhibition is not the evolution of regulatory metabolite–enzyme interactions, but a finite structural diversity prevalent within the metabolome. In eukaryotes, compartmentalization minimizes inevitable enzyme inhibition and alleviates constraints that self-inhibition places on metabolism. Metabolites act as enzyme inhibitors, but their global impact on metabolism has scarcely been considered. Here, the authors generate a human genome-wide metabolite-enzyme inhibition network, and find that inhibition occurs largely due to limited structural diversity of metabolites, leading to a global constraint on metabolism which subcellular compartmentalization minimizes.
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30
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Wahiduzzaman, Dar MA, Amir M, Islam A, Hassan MI, Ahmad F. Purification, preliminary X-ray crystallography and biophysical studies of triose phosphate isomerase-β-globin subunit complex. Int J Biol Macromol 2017; 94:746-753. [DOI: 10.1016/j.ijbiomac.2016.10.070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 10/06/2016] [Accepted: 10/21/2016] [Indexed: 02/09/2023]
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31
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Amrein BA, Steffen-Munsberg F, Szeler I, Purg M, Kulkarni Y, Kamerlin SCL. CADEE: Computer-Aided Directed Evolution of Enzymes. IUCRJ 2017; 4:50-64. [PMID: 28250941 PMCID: PMC5331465 DOI: 10.1107/s2052252516018017] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 11/09/2016] [Indexed: 05/10/2023]
Abstract
The tremendous interest in enzymes as biocatalysts has led to extensive work in enzyme engineering, as well as associated methodology development. Here, a new framework for computer-aided directed evolution of enzymes (CADEE) is presented which allows a drastic reduction in the time necessary to prepare and analyze in silico semi-automated directed evolution of enzymes. A pedagogical example of the application of CADEE to a real biological system is also presented in order to illustrate the CADEE workflow.
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Affiliation(s)
- Beat Anton Amrein
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, S-751 24 Uppsala, Sweden
| | - Fabian Steffen-Munsberg
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, S-751 24 Uppsala, Sweden
| | - Ireneusz Szeler
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, S-751 24 Uppsala, Sweden
| | - Miha Purg
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, S-751 24 Uppsala, Sweden
| | - Yashraj Kulkarni
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, S-751 24 Uppsala, Sweden
| | - Shina Caroline Lynn Kamerlin
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, S-751 24 Uppsala, Sweden
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32
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Scheiner S. Monitoring the Charge Distribution during Proton and Sodium Ion Conduction along Chains of Water Molecules and Protein Residues. Isr J Chem 2016. [DOI: 10.1002/ijch.201600062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Steve Scheiner
- Department of Chemistry and Biochemistry; Utah State University; Logan UT 84322-0300 USA
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33
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Fenwick MK, Ealick SE. Crystal Structures of the Iron-Sulfur Cluster-Dependent Quinolinate Synthase in Complex with Dihydroxyacetone Phosphate, Iminoaspartate Analogues, and Quinolinate. Biochemistry 2016; 55:4135-9. [PMID: 27404889 DOI: 10.1021/acs.biochem.6b00626] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The quinolinate synthase of prokaryotes and photosynthetic eukaryotes, NadA, contains a [4Fe-4S] cluster with unknown function. We report crystal structures of Pyrococcus horikoshii NadA in complex with dihydroxyacetone phosphate (DHAP), iminoaspartate analogues, and quinolinate. DHAP adopts a nearly planar conformation and chelates the [4Fe-4S] cluster via its keto and hydroxyl groups. The active site architecture suggests that the cluster acts as a Lewis acid in enediolate formation, like zinc in class II aldolases. The DHAP and putative iminoaspartate structures suggest a model for a condensed intermediate. The ensemble of structures suggests a two-state system, which may be exploited in early steps.
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Affiliation(s)
- Michael K Fenwick
- Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Steven E Ealick
- Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
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34
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Richard JP, Amyes TL, Malabanan MM, Zhai X, Kim KJ, Reinhardt CJ, Wierenga RK, Drake EJ, Gulick AM. Structure-Function Studies of Hydrophobic Residues That Clamp a Basic Glutamate Side Chain during Catalysis by Triosephosphate Isomerase. Biochemistry 2016; 55:3036-47. [PMID: 27149328 PMCID: PMC4934371 DOI: 10.1021/acs.biochem.6b00311] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Kinetic
parameters are reported for the reactions of whole substrates
(kcat/Km,
M–1 s–1) (R)-glyceraldehyde
3-phosphate (GAP) and
dihydroxyacetone phosphate (DHAP) and for the substrate pieces [(kcat/Km)E·HPi/Kd, M–2 s–1] glycolaldehyde (GA) and phosphite dianion
(HPi) catalyzed by the I172A/L232A mutant of triosephosphate
isomerase
from Trypanosoma brucei brucei (TbbTIM). A comparison with the corresponding parameters for wild-type,
I172A, and L232A TbbTIM-catalyzed reactions shows
that the effect of I172A and L232A mutations on ΔG⧧ for the wild-type TbbTIM-catalyzed
reactions of the substrate pieces is nearly the same
as the effect of the same mutations on TbbTIM previously
mutated at the second side chain. This provides strong evidence that
mutation of the first hydrophobic side chain does not affect the functioning
of the second side chain in catalysis of the reactions of the substrate
pieces. By contrast, the effects of I172A and L232A mutations on ΔG⧧ for wild-type TbbTIM-catalyzed
reactions of the whole substrate are different from
the effect of the same mutations on TbbTIM previously
mutated at the second side chain. This is due to the change in the
rate-determining step that determines the barrier to the isomerization
reaction. X-ray crystal structures are reported for I172A, L232A,
and I172A/L232A TIMs and for the complexes of these mutants to the
intermediate analogue phosphoglycolate (PGA). The structures of the
PGA complexes with wild-type and mutant enzymes are nearly superimposable,
except that the space opened by replacement of the hydrophobic side
chain is occupied by a water molecule that lies ∼3.5 Å
from the basic side chain of Glu167. The new water at I172A mutant TbbTIM provides a simple rationalization for the increase
in the activation barrier ΔG⧧ observed for mutant enzyme-catalyzed
reactions of the whole substrate and substrate pieces. By contrast,
the new water at the L232A mutant does not predict the decrease in
ΔG⧧ observed for the mutant
enzyme-catalyzed
reactions of the substrate piece GA.
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Affiliation(s)
- John P Richard
- Department of Chemistry, University at Buffalo, State University of New York , Buffalo, New York 14260, United States
| | - Tina L Amyes
- Department of Chemistry, University at Buffalo, State University of New York , Buffalo, New York 14260, United States
| | - M Merced Malabanan
- Department of Chemistry, University at Buffalo, State University of New York , Buffalo, New York 14260, United States
| | - Xiang Zhai
- Department of Chemistry, University at Buffalo, State University of New York , Buffalo, New York 14260, United States
| | - Kalvin J Kim
- Department of Chemistry, University at Buffalo, State University of New York , Buffalo, New York 14260, United States
| | - Christopher J Reinhardt
- Department of Chemistry, University at Buffalo, State University of New York , Buffalo, New York 14260, United States
| | - Rik K Wierenga
- Department of Biochemistry and Biocenter, University of Oulu , P.O. Box 3000, FIN-90014 Oulu, Finland
| | - Eric J Drake
- Hauptman-Woodward Institute , 700 Ellicott Street, Buffalo, New York 14203, United States.,Department of Structural Biology, University at Buffalo, State University of New York , Buffalo, New York 14203, United States
| | - Andrew M Gulick
- Hauptman-Woodward Institute , 700 Ellicott Street, Buffalo, New York 14203, United States.,Department of Structural Biology, University at Buffalo, State University of New York , Buffalo, New York 14203, United States
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35
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Pareek V, Samanta M, Joshi NV, Balaram H, Murthy MRN, Balaram P. Connecting Active-Site Loop Conformations and Catalysis in Triosephosphate Isomerase: Insights from a Rare Variation at Residue 96 in the Plasmodial Enzyme. Chembiochem 2016; 17:620-9. [PMID: 26762569 DOI: 10.1002/cbic.201500532] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Indexed: 12/12/2022]
Abstract
Despite extensive research into triosephosphate isomerases (TIMs), there exists a gap in understanding of the remarkable conjunction between catalytic loop-6 (residues 166-176) movement and the conformational flip of Glu165 (catalytic base) upon substrate binding that primes the active site for efficient catalysis. The overwhelming occurrence of serine at position 96 (98% of the 6277 unique TIM sequences), spatially proximal to E165 and the loop-6 residues, raises questions about its role in catalysis. Notably, Plasmodium falciparum TIM has an extremely rare residue--phenylalanine--at this position whereas, curiously, the mutant F96S was catalytically defective. We have obtained insights into the influence of residue 96 on the loop-6 conformational flip and E165 positioning by combining kinetic and structural studies on the PfTIM F96 mutants F96Y, F96A, F96S/S73A, and F96S/L167V with sequence conservation analysis and comparative analysis of the available apo and holo structures of the enzyme from diverse organisms.
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Affiliation(s)
- Vidhi Pareek
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Moumita Samanta
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Niranjan V Joshi
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, 560012, India
| | - Hemalatha Balaram
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, 560064, India
| | - Mathur R N Murthy
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Padmanabhan Balaram
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India.
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36
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Bioproduction of D-Tagatose from D-Galactose Using Phosphoglucose Isomerase from Pseudomonas aeruginosa PAO1. Appl Biochem Biotechnol 2016; 179:715-27. [PMID: 26922727 DOI: 10.1007/s12010-016-2026-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 02/18/2016] [Indexed: 10/22/2022]
Abstract
Pseudomonas aeruginosa PAO1 phosphoglucose isomerase was purified as an active soluble form by a single-step purification using Ni-NTA chromatography that showed homogeneity on SDS-PAGE with molecular mass ∼62 kDa. The optimum temperature and pH for the maximum isomerization activity with D-galactose were 60 °C and 7.0, respectively. Generally, sugar phosphate isomerases show metal-independent activity but PA-PGI exhibited metal-dependent isomerization activity with aldosugars and optimally catalyzed the D-galactose isomerization in the presence of 1.0 mM MnCl2. The apparent Km and Vmax for D-galactose under standardized conditions were calculated to be 1029 mM (±31.30 with S.E.) and 5.95 U/mg (±0.9 with S.E.), respectively. Equilibrium reached after 180 min with production of 567.51 μM D-tagatose from 1000 mM of D-galactose. Though, the bioconversion ratio is low but it can be increased by immobilization and enzyme engineering. Although various L-arabinose isomerases have been characterized for bioproduction of D-tagatose, P. aeruginosa glucose phosphate isomerase is distinguished from the other L-arabinose isomerases by its optimal temperature (60 °C) for D-tagatose production being mesophilic bacteria, making it an alternate choice for bulk production.
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37
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Johnson TA, Mcleod MJ, Holyoak T. Utilization of Substrate Intrinsic Binding Energy for Conformational Change and Catalytic Function in Phosphoenolpyruvate Carboxykinase. Biochemistry 2016; 55:575-87. [PMID: 26709450 DOI: 10.1021/acs.biochem.5b01215] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Phosphoenolpyruvate carboxykinase (PEPCK) is an essential metabolic enzyme operating in the gluconeogenesis and glyceroneogenesis pathways. Previous work has demonstrated that the enzyme cycles between a catalytically inactive open state and a catalytically active closed state. The transition of the enzyme between these states requires the transition of several active site loops to shift from mobile, disordered structural elements to stable ordered states. The mechanism by which these disorder-order transitions are coupled to the ligation state of the active site however is not fully understood. To further investigate the mechanisms by which the mobility of the active site loops is coupled to enzymatic function and the transitioning of the enzyme between the two conformational states, we have conducted structural and functional studies of point mutants of E89. E89 is a proposed key member of the interaction network of mobile elements as it resides in the R-loop region of the enzyme active site. These new data demonstrate the importance of the R-loop in coordinating interactions between substrates at the OAA/PEP binding site and the mobile R- and Ω-loop domains. In turn, the studies more generally demonstrate the mechanisms by which the intrinsic ligand binding energy can be utilized in catalysis to drive unfavorable conformational changes, changes that are subsequently required for both optimal catalytic activity and fidelity.
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Affiliation(s)
- Troy A Johnson
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center , Kansas City, Kansas 66160, United States
| | - Matthew J Mcleod
- Department of Biology, University of Waterloo , Waterloo, ON N2L 3G1, Canada
| | - Todd Holyoak
- Department of Biology, University of Waterloo , Waterloo, ON N2L 3G1, Canada.,Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center , Kansas City, Kansas 66160, United States
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38
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López-Castillo LM, Jiménez-Sandoval P, Baruch-Torres N, Trasviña-Arenas CH, Díaz-Quezada C, Lara-González S, Winkler R, Brieba LG. Structural Basis for Redox Regulation of Cytoplasmic and Chloroplastic Triosephosphate Isomerases from Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2016; 7:1817. [PMID: 27999583 PMCID: PMC5138414 DOI: 10.3389/fpls.2016.01817] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 11/18/2016] [Indexed: 05/04/2023]
Abstract
In plants triosephosphate isomerase (TPI) interconverts glyceraldehyde 3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP) during glycolysis, gluconeogenesis, and the Calvin-Benson cycle. The nuclear genome of land plants encodes two tpi genes, one gene product is located in the cytoplasm and the other is imported into the chloroplast. Herein we report the crystal structures of the TPIs from the vascular plant Arabidopsis thaliana (AtTPIs) and address their enzymatic modulation by redox agents. Cytoplasmic TPI (cTPI) and chloroplast TPI (pdTPI) share more than 60% amino acid identity and assemble as (β-α)8 dimers with high structural homology. cTPI and pdTPI harbor two and one accessible thiol groups per monomer respectively. cTPI and pdTPI present a cysteine at an equivalent structural position (C13 and C15 respectively) and cTPI also contains a specific solvent accessible cysteine at residue 218 (cTPI-C218). Site directed mutagenesis of residues pdTPI-C15, cTPI-C13, and cTPI-C218 to serine substantially decreases enzymatic activity, indicating that the structural integrity of these cysteines is necessary for catalysis. AtTPIs exhibit differential responses to oxidative agents, cTPI is susceptible to oxidative agents such as diamide and H2O2, whereas pdTPI is resistant to inhibition. Incubation of AtTPIs with the sulfhydryl conjugating reagents methylmethane thiosulfonate (MMTS) and glutathione inhibits enzymatic activity. However, the concentration necessary to inhibit pdTPI is at least two orders of magnitude higher than the concentration needed to inhibit cTPI. Western-blot analysis indicates that residues cTPI-C13, cTPI-C218, and pdTPI-C15 conjugate with glutathione. In summary, our data indicate that AtTPIs could be redox regulated by the derivatization of specific AtTPI cysteines (cTPI-C13 and pdTPI-C15 and cTPI-C218). Since AtTPIs have evolved by gene duplication, the higher resistance of pdTPI to redox agents may be an adaptive consequence to the redox environment in the chloroplast.
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Affiliation(s)
- Laura M. López-Castillo
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico NacionalIrapuato Guanajuato, Mexico
- Departamento de Biotecnología y Bioquímica, CINVESTAV Unidad IrapuatoIrapuato Guanajuato, Mexico
| | - Pedro Jiménez-Sandoval
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico NacionalIrapuato Guanajuato, Mexico
| | - Noe Baruch-Torres
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico NacionalIrapuato Guanajuato, Mexico
| | - Carlos H. Trasviña-Arenas
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico NacionalIrapuato Guanajuato, Mexico
| | - Corina Díaz-Quezada
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico NacionalIrapuato Guanajuato, Mexico
| | - Samuel Lara-González
- División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica A.C.San Luis Potosí, Mexico
| | - Robert Winkler
- Departamento de Biotecnología y Bioquímica, CINVESTAV Unidad IrapuatoIrapuato Guanajuato, Mexico
| | - Luis G. Brieba
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico NacionalIrapuato Guanajuato, Mexico
- *Correspondence: Luis G. Brieba
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39
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Zhai X, Amyes TL, Richard JP. Role of Loop-Clamping Side Chains in Catalysis by Triosephosphate Isomerase. J Am Chem Soc 2015; 137:15185-97. [PMID: 26570983 PMCID: PMC4694050 DOI: 10.1021/jacs.5b09328] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
The side chains of
Y208 and S211 from loop 7 of triosephosphate
isomerase (TIM) form hydrogen bonds to backbone amides and carbonyls
from loop 6 to stabilize the caged enzyme–substrate complex.
The effect of seven mutations [Y208T, Y208S, Y208A, Y208F, S211G,
S211A, Y208T/S211G] on the kinetic parameters for TIM catalyzed reactions
of the whole substrates dihydroxyacetone phosphate and d-glyceraldehyde
3-phosphate [(kcat/Km)GAP and (kcat/Km)DHAP] and of the substrate pieces
glycolaldehyde and phosphite dianion (kcat/KHPiKGA)
are reported. The linear logarithmic correlation between these kinetic
parameters, with slope of 1.04 ± 0.03, shows that most mutations
of TIM result in an identical change in the activation barriers for
the catalyzed reactions of whole substrate and substrate pieces, so
that the transition states for these reactions are stabilized by similar
interactions with the protein catalyst. The second linear logarithmic
correlation [slope = 0.53 ± 0.16] between kcat for isomerization of GAP and Kd⧧ for phosphite dianion binding to the transition
state for wildtype and many mutant TIM-catalyzed reactions of substrate
pieces shows that ca. 50% of the wildtype TIM dianion binding energy,
eliminated by these mutations, is expressed at the wildtype Michaelis
complex, and ca. 50% is only expressed at the wildtype transition
state. Negative deviations from this correlation are observed when
the mutation results in a decrease in enzyme reactivity at the catalytic
site. The main effect of Y208T, Y208S, and Y208A mutations is to cause
a reduction in the total intrinsic dianion binding energy, but the
effect of Y208F extends to the catalytic site.
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Affiliation(s)
- Xiang Zhai
- Department of Chemistry, University at Buffalo, SUNY , Buffalo, New York 14260-3000, United States
| | - Tina L Amyes
- Department of Chemistry, University at Buffalo, SUNY , Buffalo, New York 14260-3000, United States
| | - John P Richard
- Department of Chemistry, University at Buffalo, SUNY , Buffalo, New York 14260-3000, United States
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40
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Mendieta-Moreno JI, Marcos-Alcalde I, Trabada DG, Gómez-Puertas P, Ortega J, Mendieta J. A Practical Quantum Mechanics Molecular Mechanics Method for the Dynamical Study of Reactions in Biomolecules. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2015; 100:67-88. [PMID: 26415841 DOI: 10.1016/bs.apcsb.2015.06.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Quantum mechanics/molecular mechanics (QM/MM) methods are excellent tools for the modeling of biomolecular reactions. Recently, we have implemented a new QM/MM method (Fireball/Amber), which combines an efficient density functional theory method (Fireball) and a well-recognized molecular dynamics package (Amber), offering an excellent balance between accuracy and sampling capabilities. Here, we present a detailed explanation of the Fireball method and Fireball/Amber implementation. We also discuss how this tool can be used to analyze reactions in biomolecules using steered molecular dynamics simulations. The potential of this approach is shown by the analysis of a reaction catalyzed by the enzyme triose-phosphate isomerase (TIM). The conformational space and energetic landscape for this reaction are analyzed without a priori assumptions about the protonation states of the different residues during the reaction. The results offer a detailed description of the reaction and reveal some new features of the catalytic mechanism. In particular, we find a new reaction mechanism that is characterized by the intramolecular proton transfer from O1 to O2 and the simultaneous proton transfer from Glu 165 to C2.
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Affiliation(s)
- Jesús I Mendieta-Moreno
- Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, Spain; Molecular Modelling Group, Center of Molecular Biology "Severo Ochoa" (CSIC-UAM), Madrid, Spain
| | - Iñigo Marcos-Alcalde
- Molecular Modelling Group, Center of Molecular Biology "Severo Ochoa" (CSIC-UAM), Madrid, Spain
| | - Daniel G Trabada
- Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, Spain
| | - Paulino Gómez-Puertas
- Molecular Modelling Group, Center of Molecular Biology "Severo Ochoa" (CSIC-UAM), Madrid, Spain
| | - José Ortega
- Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, Spain.
| | - Jesús Mendieta
- Molecular Modelling Group, Center of Molecular Biology "Severo Ochoa" (CSIC-UAM), Madrid, Spain; Biomol-Informatics SL, Campus UAM, Madrid, Spain
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41
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Kumar K, Muthamilarasan M, Bonthala VS, Roy R, Prasad M. Unraveling 14-3-3 proteins in C4 panicoids with emphasis on model plant Setaria italica reveals phosphorylation-dependent subcellular localization of RS splicing factor. PLoS One 2015; 10:e0123236. [PMID: 25849294 PMCID: PMC4388342 DOI: 10.1371/journal.pone.0123236] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 03/01/2015] [Indexed: 11/18/2022] Open
Abstract
14-3-3 proteins are a large multigenic family of regulatory proteins ubiquitously found in eukaryotes. In plants, 14-3-3 proteins are reported to play significant role in both development and response to stress stimuli. Therefore, considering their importance, genome-wide analyses have been performed in many plants including Arabidopsis, rice and soybean. But, till date, no comprehensive investigation has been conducted in any C4 panicoid crops. In view of this, the present study was performed to identify 8, 5 and 26 potential 14-3-3 gene family members in foxtail millet (Si14-3-3), sorghum (Sb14-3-3) and maize (Zm14-3-3), respectively. In silico characterization revealed large variations in their gene structures; segmental and tandem duplications have played a major role in expansion of these genes in foxtail millet and maize. Gene ontology annotation showed the participation of 14-3-3 proteins in diverse biological processes and molecular functions, and in silico expression profiling indicated their higher expression in all the investigated tissues. Comparative mapping was performed to derive the orthologous relationships between 14-3-3 genes of foxtail millet and other Poaceae members, which showed a higher, as well as similar percentage of orthology among these crops. Expression profiling of Si14-3-3 genes during different time-points of abiotic stress and hormonal treatments showed a differential expression pattern of these genes, and sub-cellular localization studies revealed the site of action of Si14-3-3 proteins within the cells. Further downstream characterization indicated the interaction of Si14-3-3 with a nucleocytoplasmic shuttling phosphoprotein (SiRSZ21A) in a phosphorylation-dependent manner, and this demonstrates that Si14-3-3 might regulate the splicing events by binding with phosphorylated SiRSZ21A. Taken together, the present study is a comprehensive analysis of 14-3-3 gene family members in foxtail millet, sorghum and maize, which provides interesting information on their gene structure, protein domains, phylogenetic and evolutionary relationships, and expression patterns during abiotic stresses and hormonal treatments, which could be useful in choosing candidate members for further functional characterization. In addition, demonstration of interaction between Si14-3-3 and SiRSZ21A provides novel clues on the involvement of 14-3-3 proteins in the splicing events.
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Affiliation(s)
- Karunesh Kumar
- National Institute of Plant Genome Research (NIPGR), New Delhi, India
| | | | | | - Riti Roy
- National Institute of Plant Genome Research (NIPGR), New Delhi, India
| | - Manoj Prasad
- National Institute of Plant Genome Research (NIPGR), New Delhi, India
- * E-mail:
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Proteomic Analysis Reveals PGAM1 Altering cis-9, trans-11 Conjugated Linoleic Acid Synthesis in Bovine Mammary Gland. Lipids 2015; 50:469-81. [PMID: 25820808 DOI: 10.1007/s11745-015-4009-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 03/09/2015] [Indexed: 10/23/2022]
Abstract
cis-9, trans-11 Conjugated linoleic acid (CLA) is one of the most extensively studied CLA isomers due to its multiple isomer-specific effects. However, the molecular mechanisms of cis-9,trans-11 CLA synthesis in ruminant mammary gland are still not clearly understood. This process may be mediated, to a certain extent, by trans-11 C18:1 regulated by stearoyl-CoA desaturase-1 (SCD1) and/or its syntrophic proteins. This study aimed to investigate the effects of TVA on SCD1-mediated cis-9,trans-11 CLA synthesis in MAC-T cells and its potential molecular mechanism. Results showed that trans-11 C18:1 was continually taken up and converted into cis-9,trans-11 CLA in MAC-T cells during the 4-h incubation of 50 μM trans-11 C18:1. SCD1 protein expression increased more than twofold at 2 h (P < 0.01) and 2.5 h (P < 0.05) before decreasing to less than half of the normal level at 4 h (P < 0.05). One up-regulated (RAS guanyl releasing protein 4 isoform 1 [RASGRP4]) and six down-regulated proteins (glucosamine-6-phosphate deaminase 1 [GNPDA1], triosephosphate isomerase [TPI1], phosphoglycerate mutase 1 [PGAM1], heat shock protein beta-1 [HSPB1], annexin A3 [ANXA3], thiopurine S-methyltransferase [TPMT]) were found in MAC-T cells treated with trans-11 C18:1. Of these seven identified proteins, the presence of GNPDA1 and PGAM1 was verified in several models. More trans-11 C18:1 was taken up after PGAM1 knockdown by small interfering RNA (siRNA). In conclusion, our data suggested that PGAM1 may have a negative relationship with SCD1 and seemed to be involved in cis-9, trans-11 CLA synthesis by facilitating the absorption of trans-11 C18:1 in the bovine mammary gland.
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Bonjack-Shterengartz M, Avnir D. The near-symmetry of proteins. Proteins 2015; 83:722-34. [PMID: 25354765 DOI: 10.1002/prot.24706] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 10/06/2014] [Accepted: 10/18/2014] [Indexed: 11/07/2022]
Abstract
The majority of protein oligomers form clusters which are nearly symmetric. Understanding of that imperfection, its origins, and perhaps also its advantages requires the conversion of the currently used vague qualitative descriptive language of the near-symmetry into an accurate quantitative measure that will allow to answer questions such as: "What is the degree of symmetry deviation of the protein?," "how do these deviations compare within a family of proteins?," and so on. We developed quantitative methods to answer this type of questions, which are capable of analyzing the whole protein, its backbone or selected portions of it, down to comparison of symmetry-related specific amino-acids, and which are capable of visualizing the various levels of symmetry deviations in the form of symmetry maps. We have applied these methods on an extensive list of homomers and heteromers and found that apparently all proteins never reach perfect symmetry. Strikingly, even homomeric protein clusters are never ideally symmetric. We also found that the main burden of symmetry distortion is on the amino-acids near the symmetry axis; that it is mainly the more hydrophilic amino-acids that take place in symmetry-distortive interactions; and more. The remarkable ability of heteromers to preserve near-symmetry, despite the different sequences, was also shown and analyzed. The comprehensive literature on the suggested advantages symmetric oligomerizations raises a yet-unsolved key question: If symmetry is so advantageous, why do proteins stop shy of perfect symmetry? Some tentative answers to be tested in further studies are suggested in a concluding outlook.
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Affiliation(s)
- Maayan Bonjack-Shterengartz
- Institute of Chemistry and the Lise Meitner Minerva Center for Computational Quantum Chemistry, the Hebrew University of Jerusalem, Jerusalem, 91904, Israel
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Triosephosphate isomerase I170V alters catalytic site, enhances stability and induces pathology in a Drosophila model of TPI deficiency. Biochim Biophys Acta Mol Basis Dis 2014; 1852:61-9. [PMID: 25463631 DOI: 10.1016/j.bbadis.2014.10.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 10/01/2014] [Accepted: 10/10/2014] [Indexed: 12/13/2022]
Abstract
Triosephosphate isomerase (TPI) is a glycolytic enzyme which homodimerizes for full catalytic activity. Mutations of the TPI gene elicit a disease known as TPI Deficiency, a glycolytic enzymopathy noted for its unique severity of neurological symptoms. Evidence suggests that TPI Deficiency pathogenesis may be due to conformational changes of the protein, likely affecting dimerization and protein stability. In this report, we genetically and physically characterize a human disease-associated TPI mutation caused by an I170V substitution. Human TPI(I170V) elicits behavioral abnormalities in Drosophila. An examination of hTPI(I170V) enzyme kinetics revealed this substitution reduced catalytic turnover, while assessments of thermal stability demonstrated an increase in enzyme stability. The crystal structure of the homodimeric I170V mutant reveals changes in the geometry of critical residues within the catalytic pocket. Collectively these data reveal new observations of the structural and kinetic determinants of TPI Deficiency pathology, providing new insights into disease pathogenesis.
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Richard JP, Zhai X, Malabanan MM. Reflections on the catalytic power of a TIM-barrel. Bioorg Chem 2014; 57:206-212. [PMID: 25092608 DOI: 10.1016/j.bioorg.2014.07.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 07/03/2014] [Accepted: 07/04/2014] [Indexed: 12/14/2022]
Abstract
The TIM-barrel fold is described and its propagation throughout the enzyme universe noted. The functions of the individual front loops of the eponymous TIM-barrel of triosephosphate isomerase are presented in a discussion of: (a) electrophilic catalysis, by amino acid side chains from loops 1 and 4, of abstraction of an α-carbonyl hydrogen from substrate dihydroxyacetone phosphate (DHAP) or d-glyceraldehyde 3-phosphate (DGAP). (b) The engineering of loop 3 to give the monomeric variant monoTIM and the structure and catalytic properties of this monomer. (c) The interaction between loops 6, 7 and 8 and the phosphodianion of DHAP or DGAP. (d) The mechanism by which a ligand-gated conformational change, dominated by motion of loops 6 and 7, activates TIM for catalysis of deprotonation of DHAP or DGAP. (e) The conformational plasticity of TIM, and the utilization of substrate binding energy to "mold" the distorted active site loops of TIM mutants into catalytically active enzymes. The features of the TIM-barrel fold that favor effective protein catalysis are discussed.
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Affiliation(s)
- John P Richard
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, NY 14260, United States.
| | - Xiang Zhai
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, NY 14260, United States
| | - M Merced Malabanan
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, NY 14260, United States
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Zhai X, Malabanan MM, Amyes TL, Richard JP. Mechanistic Imperatives for Deprotonation of Carbon Catalyzed by Triosephosphate Isomerase: Enzyme-Activation by Phosphite Dianion. J PHYS ORG CHEM 2014; 27:269-276. [PMID: 24729658 PMCID: PMC3979633 DOI: 10.1002/poc.3195] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The mechanistic imperatives for catalysis of deprotonation of α-carbonyl carbon by triosephosphate isomerase (TIM) are discussed. There is a strong imperative to reduce the large thermodynamic barrier for deprotonation of carbon to form an enediolate reaction intermediate; and, a strong imperative for specificity in the expression of the intrinsic phosphodianion binding energy at the transition state for the enzyme-catalyzed reaction. Binding energies of 2 and 6 kcal/mol, respectively, have been determined for formation of phosphite dianion complexes to TIM and to the transition state for TIM-catalyzed deprotonation of the truncated substrate glycolaldehyde [T. L. Amyes, J. P. Richard, Biochemistry2007, 46, 5841]. We propose that the phosphite dianion binding energy, which is specifically expressed at the transition state complex, is utilized to stabilize a rare catalytically active loop-closed form of TIM. The results of experiments to probe the role of the side chains of Ile172 and Leu232 in activating the loop-closed form of TIM for catalysis of substrate deprotonation are discussed. Evidence is presented that the hydrophobic side chain of Ile172 assists in activating TIM for catalysis of substrate deprotonation through an enhancement of the basicity of the carboxylate side-chain of Glu167. Our experiments link the two imperatives for TIM-catalyzed deprotonation of carbon by providing evidence that the phosphodianion binding energy is utilized to drive an enzyme conformational change, which results in a reduction in the thermodynamic barrier to deprotonation of the carbon acid substrate at TIM compared with the barrier for deprotonation in water. The effects of a P168A mutation on the kinetic parameters for the reactions of whole and truncated substrates are discussed.
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Affiliation(s)
- Xiang Zhai
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, NY 14260, USA
| | - M Merced Malabanan
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, NY 14260, USA
| | - Tina L Amyes
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, NY 14260, USA
| | - John P Richard
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, NY 14260, USA
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Richard JP, Amyes TL, Goryanova B, Zhai X. Enzyme architecture: on the importance of being in a protein cage. Curr Opin Chem Biol 2014; 21:1-10. [PMID: 24699188 DOI: 10.1016/j.cbpa.2014.03.001] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 03/01/2014] [Indexed: 11/30/2022]
Abstract
Substrate binding occludes water from the active sites of many enzymes. There is a correlation between the burden to enzymatic catalysis of deprotonation of carbon acids and the substrate immobilization at solvent-occluded active sites for ketosteroid isomerase (KSI--small burden, substrate pKa=13), triosephosphate isomerase (TIM, substrate pKa≈18) and diaminopimelate epimerase (DAP epimerase, large burden, substrate pKa≈29) catalyzed reaction. KSI binds substrates at a surface cleft, TIM binds substrate at an exposed 'cage' formed by closure of flexible loops; and, DAP epimerase binds substrate in a tight cage formed by an 'oyster-like' clamping motion of protein domains. Directed evolution of a solvent-occluded active site at a designed protein catalyst of the Kemp elimination reaction is discussed.
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Affiliation(s)
- John P Richard
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, NY 14260-3000, USA.
| | - Tina L Amyes
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, NY 14260-3000, USA
| | - Bogdana Goryanova
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, NY 14260-3000, USA
| | - Xiang Zhai
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, NY 14260-3000, USA
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Zhai X, Amyes TL, Richard JP. Enzyme architecture: remarkably similar transition states for triosephosphate isomerase-catalyzed reactions of the whole substrate and the substrate in pieces. J Am Chem Soc 2014; 136:4145-8. [PMID: 24588650 PMCID: PMC3985921 DOI: 10.1021/ja501103b] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Values of (kcat/Km)GAP for triosephosphate
isomerase-catalyzed reactions
of (R)-glyceraldehyde 3-phosphate and kcat/KHPiKGA for reactions of the substrate pieces glycolaldehyde
and HPO32– have been determined for wild-type
and the following TIM mutants: I172V, I172A, L232A, and P168A (TIM
from Trypanosoma brucei brucei); a
208-TGAG for 208-YGGS loop 7 replacement mutant (L7RM, TIM from chicken
muscle); and, Y208T, Y208S, Y208A, Y208F and S211A (yeast TIM). A
superb linear logarithmic correlation, with slope of 1.04 ± 0.03,
is observed between the kinetic parameters for wild-type and most
mutant enzymes, with positive deviations for L232A and L7RM. The unit
slope shows that most mutations result in an identical change in the
activation barriers for the catalyzed reactions of whole substrate
and substrate pieces, so that the two transition states are stabilized
by similar interactions with the protein catalyst. This is consistent
with a role for dianions as active spectators, which hold TIM in a
catalytically active caged form.
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Affiliation(s)
- Xiang Zhai
- Department of Chemistry, University at Buffalo, State University of New York , Buffalo, New York 14260, United States
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Grüning NM, Du D, Keller MA, Luisi BF, Ralser M. Inhibition of triosephosphate isomerase by phosphoenolpyruvate in the feedback-regulation of glycolysis. Open Biol 2014; 4:130232. [PMID: 24598263 PMCID: PMC3971408 DOI: 10.1098/rsob.130232] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The inhibition of triosephosphate isomerase (TPI) in glycolysis by the pyruvate kinase (PK) substrate phosphoenolpyruvate (PEP) results in a newly discovered feedback loop that counters oxidative stress in cancer and actively respiring cells. The mechanism underlying this inhibition is illuminated by the co-crystal structure of TPI with bound PEP at 1.6 Å resolution, and by mutational studies guided by the crystallographic results. PEP is bound to the catalytic pocket of TPI and occludes substrate, which accounts for the observation that PEP competitively inhibits the interconversion of glyceraldehyde-3-phosphate and dihydroxyacetone phosphate. Replacing an isoleucine residue located in the catalytic pocket of TPI with valine or threonine altered binding of substrates and PEP, reducing TPI activity in vitro and in vivo. Confirming a TPI-mediated activation of the pentose phosphate pathway (PPP), transgenic yeast cells expressing these TPI mutations accumulate greater levels of PPP intermediates and have altered stress resistance, mimicking the activation of the PK-TPI feedback loop. These results support a model in which glycolytic regulation requires direct catalytic inhibition of TPI by the pyruvate kinase substrate PEP, mediating a protective metabolic self-reconfiguration of central metabolism under conditions of oxidative stress.
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Affiliation(s)
- Nana-Maria Grüning
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
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Katebi AR, Jernigan RL. The critical role of the loops of triosephosphate isomerase for its oligomerization, dynamics, and functionality. Protein Sci 2013; 23:213-28. [PMID: 24318986 DOI: 10.1002/pro.2407] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 12/01/2013] [Accepted: 12/03/2013] [Indexed: 11/11/2022]
Abstract
Triosephosphate isomerase (TIM) catalyzes the reaction to convert dihydroxyacetone phosphate into glyceraldehyde 3-phosphate, and vice versa. In most organisms, its functional oligomeric state is a homodimer; however, tetramer formation in hyperthermophiles is required for functional activity. The tetrameric TIM structure also provides added stability to the structure, enabling it to function at more extreme temperatures. We apply Principal Component Analysis to find that the TIM structure space is clearly divided into two groups--the open and the closed TIM structures. The distribution of the structures in the open set is much sparser than that in the closed set, showing a greater conformational diversity of the open structures. We also apply the Elastic Network Model to four different TIM structures--an engineered monomeric structure, a dimeric structure from a mesophile--Trypanosoma brucei, and two tetrameric structures from hyperthermophiles Thermotoga maritima and Pyrococcus woesei. We find that dimerization not only stabilizes the structures, it also enhances their functional dynamics. Moreover, tetramerization of the hyperthermophilic structures increases their functional loop dynamics, enabling them to function in the destabilizing environment of extreme temperatures. Computations also show that the functional loop motions, especially loops 6 and 7, are highly coordinated. In summary, our computations reveal the underlying mechanism of the allosteric regulation of the functional loops of the TIM structures, and show that tetramerization of the structure as found in the hyperthermophilic organisms is required to maintain the coordination of the functional loops at a level similar to that in the dimeric mesophilic structure.
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Affiliation(s)
- Ataur R Katebi
- Department of Biochemistry, Biophysics and Molecular Biology, LH Baker Center for Bioinformatics and Biological Statistics, Interdepartmental Program for Bioinformatics and Computational Biology, Iowa State University, Ames, Iowa, 50011-3020
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