1
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Krishnan A, Waheed SO, Varghese A, Cherilakkudy FH, Schofield CJ, Karabencheva-Christova TG. Unusual catalytic strategy by non-heme Fe(ii)/2-oxoglutarate-dependent aspartyl hydroxylase AspH. Chem Sci 2024; 15:3466-3484. [PMID: 38455014 PMCID: PMC10915816 DOI: 10.1039/d3sc05974j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 02/02/2024] [Indexed: 03/09/2024] Open
Abstract
Biocatalytic C-H oxidation reactions are of important synthetic utility, provide a sustainable route for selective synthesis of important organic molecules, and are an integral part of fundamental cell processes. The multidomain non-heme Fe(ii)/2-oxoglutarate (2OG) dependent oxygenase AspH catalyzes stereoselective (3R)-hydroxylation of aspartyl- and asparaginyl-residues. Unusually, compared to other 2OG hydroxylases, crystallography has shown that AspH lacks the carboxylate residue of the characteristic two-His-one-Asp/Glu Fe-binding triad. Instead, AspH has a water molecule that coordinates Fe(ii) in the coordination position usually occupied by the Asp/Glu carboxylate. Molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) studies reveal that the iron coordinating water is stabilized by hydrogen bonding with a second coordination sphere (SCS) carboxylate residue Asp721, an arrangement that helps maintain the six coordinated Fe(ii) distorted octahedral coordination geometry and enable catalysis. AspH catalysis follows a dioxygen activation-hydrogen atom transfer (HAT)-rebound hydroxylation mechanism, unusually exhibiting higher activation energy for rebound hydroxylation than for HAT, indicating that the rebound step may be rate-limiting. The HAT step, along with substrate positioning modulated by the non-covalent interactions with SCS residues (Arg688, Arg686, Lys666, Asp721, and Gln664), are essential in determining stereoselectivity, which likely proceeds with retention of configuration. The tetratricopeptide repeat (TPR) domain of AspH influences substrate binding and manifests dynamic motions during catalysis, an observation of interest with respect to other 2OG oxygenases with TPR domains. The results provide unique insights into how non-heme Fe(ii) oxygenases can effectively catalyze stereoselective hydroxylation using only two enzyme-derived Fe-ligating residues, potentially guiding enzyme engineering for stereoselective biocatalysis, thus advancing the development of non-heme Fe(ii) based biomimetic C-H oxidation catalysts, and supporting the proposal that the 2OG oxygenase superfamily may be larger than once perceived.
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Affiliation(s)
- Anandhu Krishnan
- Department of Chemistry, Michigan Technological University Houghton MI 49931 USA
| | - Sodiq O Waheed
- Department of Chemistry, Michigan Technological University Houghton MI 49931 USA
| | - Ann Varghese
- Department of Chemistry, Michigan Technological University Houghton MI 49931 USA
| | | | - Christopher J Schofield
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford OX1 3TA Oxford UK
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2
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Nam K, Shao Y, Major DT, Wolf-Watz M. Perspectives on Computational Enzyme Modeling: From Mechanisms to Design and Drug Development. ACS OMEGA 2024; 9:7393-7412. [PMID: 38405524 PMCID: PMC10883025 DOI: 10.1021/acsomega.3c09084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/15/2024] [Accepted: 01/19/2024] [Indexed: 02/27/2024]
Abstract
Understanding enzyme mechanisms is essential for unraveling the complex molecular machinery of life. In this review, we survey the field of computational enzymology, highlighting key principles governing enzyme mechanisms and discussing ongoing challenges and promising advances. Over the years, computer simulations have become indispensable in the study of enzyme mechanisms, with the integration of experimental and computational exploration now established as a holistic approach to gain deep insights into enzymatic catalysis. Numerous studies have demonstrated the power of computer simulations in characterizing reaction pathways, transition states, substrate selectivity, product distribution, and dynamic conformational changes for various enzymes. Nevertheless, significant challenges remain in investigating the mechanisms of complex multistep reactions, large-scale conformational changes, and allosteric regulation. Beyond mechanistic studies, computational enzyme modeling has emerged as an essential tool for computer-aided enzyme design and the rational discovery of covalent drugs for targeted therapies. Overall, enzyme design/engineering and covalent drug development can greatly benefit from our understanding of the detailed mechanisms of enzymes, such as protein dynamics, entropy contributions, and allostery, as revealed by computational studies. Such a convergence of different research approaches is expected to continue, creating synergies in enzyme research. This review, by outlining the ever-expanding field of enzyme research, aims to provide guidance for future research directions and facilitate new developments in this important and evolving field.
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Affiliation(s)
- Kwangho Nam
- Department
of Chemistry and Biochemistry, University
of Texas at Arlington, Arlington, Texas 76019, United States
| | - Yihan Shao
- Department
of Chemistry and Biochemistry, University
of Oklahoma, Norman, Oklahoma 73019-5251, United States
| | - Dan T. Major
- Department
of Chemistry and Institute for Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
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3
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Abstract
Debate has been simmering for some years regarding the importance of internal thermal motions of enzymes to catalysis. Recent developments in protein design may bring resolution of the more contentious points a little closer.
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Affiliation(s)
- Jeremy R. H. Tame
- Protein Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Suehiro 1-7-29, Tsurumi, Yokohama, 230-0045 Japan
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4
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Antoniou D, Zoi I, Schwartz SD. Atomistic description of the relationship between protein dynamics and catalysis with transition path sampling. Methods Enzymol 2023; 685:319-340. [PMID: 37245906 PMCID: PMC10228753 DOI: 10.1016/bs.mie.2023.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Despite initial resistance, it has been increasingly accepted that protein dynamics plays a role in enzymatic catalysis. There have been two lines of research. Some works study slow conformational motions that are not coupled to the reaction coordinate, but guide the system towards catalytically competent conformations. Understanding at the atomistic level how this is accomplished has remained elusive except for a few systems. In this review we focus on fast sub-picosecond motions that are coupled to the reaction coordinate. The use of Transition Path Sampling has allowed us an atomistic description of how these rate-promoting vibrational motions are incorporated in the reaction mechanism. We will also show how we used insights from rate-promoting motions in protein design.
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Affiliation(s)
- Dimitri Antoniou
- Department of Biochemistry, University of Arizona, Tucson, AZ, United States
| | - Ioanna Zoi
- Department of Biochemistry, University of Arizona, Tucson, AZ, United States
| | - Steven D Schwartz
- Department of Biochemistry, University of Arizona, Tucson, AZ, United States.
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5
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Abstract
This Perspective presents a review of our work and that of others in the highly controversial topic of the coupling of protein dynamics to reaction in enzymes. We have been involved in studying this topic for many years. Thus, this perspective will naturally present our own views, but it also is designed to present an overview of the variety of viewpoints of this topic, both experimental and theoretical. This is obviously a large and contentious topic.
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Affiliation(s)
- Steven D Schwartz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
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6
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Ouedraogo D, Souffrant M, Yao XQ, Hamelberg D, Gadda G. Non-active Site Residue in Loop L4 Alters Substrate Capture and Product Release in d-Arginine Dehydrogenase. Biochemistry 2023; 62:1070-1081. [PMID: 36795942 PMCID: PMC9996824 DOI: 10.1021/acs.biochem.2c00697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Numerous studies demonstrate that enzymes undergo multiple conformational changes during catalysis. The malleability of enzymes forms the basis for allosteric regulation: residues located far from the active site can exert long-range dynamical effects on the active site residues to modulate catalysis. The structure of Pseudomonas aeruginosa d-arginine dehydrogenase (PaDADH) shows four loops (L1, L2, L3, and L4) that span the substrate and the FAD-binding domains. Loop L4 comprises residues 329-336, spanning over the flavin cofactor. The I335 residue on loop L4 is ∼10 Å away from the active site and ∼3.8 Å from N(1)-C(2)═O atoms of the flavin. In this study, we used molecular dynamics and biochemical techniques to investigate the effect of the mutation of I335 to histidine on the catalytic function of PaDADH. Molecular dynamics showed that the conformational dynamics of PaDADH are shifted to a more closed conformation in the I335H variant. In agreement with an enzyme that samples more in a closed conformation, the kinetic data of the I335H variant showed a 40-fold decrease in the rate constant of substrate association (k1), a 340-fold reduction in the rate constant of substrate dissociation from the enzyme-substrate complex (k2), and a 24-fold decrease in the rate constant of product release (k5), compared to that of the wild-type. Surprisingly, the kinetic data are consistent with the mutation having a negligible effect on the reactivity of the flavin. Altogether, the data indicate that the residue at position 335 has a long-range dynamical effect on the catalytic function in PaDADH.
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Affiliation(s)
- Daniel Ouedraogo
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Michael Souffrant
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Xin-Qiu Yao
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Donald Hamelberg
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.,Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30302, United States.,Center for Biotechnology and Drug Design, Georgia State University, Atlanta, Georgia 30302, United States
| | - Giovanni Gadda
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.,Department of Biology, Georgia State University, Atlanta, Georgia 30302, United States.,Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30302, United States.,Center for Biotechnology and Drug Design, Georgia State University, Atlanta, Georgia 30302, United States
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7
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Doukov T, Herschlag D, Yabukarski F. Obtaining anomalous and ensemble information from protein crystals from 220 K up to physiological temperatures. Acta Crystallogr D Struct Biol 2023; 79:212-223. [PMID: 36876431 PMCID: PMC9986799 DOI: 10.1107/s205979832300089x] [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: 11/03/2022] [Accepted: 01/31/2023] [Indexed: 03/01/2023] Open
Abstract
X-ray crystallography has been invaluable in delivering structural information about proteins. Previously, an approach has been developed that allows high-quality X-ray diffraction data to be obtained from protein crystals at and above room temperature. Here, this previous work is built on and extended by showing that high-quality anomalous signal can be obtained from single protein crystals using diffraction data collected at 220 K up to physiological temperatures. The anomalous signal can be used to directly determine the structure of a protein, i.e. to phase the data, as is routinely performed under cryoconditions. This ability is demonstrated by obtaining diffraction data from model lysozyme, thaumatin and proteinase K crystals, the anomalous signal from which allowed their structures to be solved experimentally at 7.1 keV X-ray energy and at room temperature with relatively low data redundancy. It is also demonstrated that the anomalous signal from diffraction data obtained at 310 K (37°C) can be used to solve the structure of proteinase K and to identify ordered ions. The method provides useful anomalous signal at temperatures down to 220 K, resulting in an extended crystal lifetime and increased data redundancy. Finally, we show that useful anomalous signal can be obtained at room temperature using X-rays of 12 keV energy as typically used for routine data collection, allowing this type of experiment to be carried out at widely accessible synchrotron beamline energies and enabling the simultaneous extraction of high-resolution data and anomalous signal. With the recent emphasis on obtaining conformational ensemble information for proteins, the high resolution of the data allows such ensembles to be built, while the anomalous signal allows the structure to be experimentally solved, ions to be identified, and water molecules and ions to be differentiated. Because bound metal-, phosphorus- and sulfur-containing ions all have anomalous signal, obtaining anomalous signal across temperatures and up to physiological temperatures will provide a more complete description of protein conformational ensembles, function and energetics.
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Affiliation(s)
- Tzanko Doukov
- SMB, Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Daniel Herschlag
- Deparment of Biochemistry, Stanford University, Stanford, CA 94305, USA
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
- Stanford ChEM-H, Stanford University, Stanford, CA 94305, USA
| | - Filip Yabukarski
- Deparment of Biochemistry, Stanford University, Stanford, CA 94305, USA
- Bristol-Myers Squibb, San Diego, CA 92121, USA
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8
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Borg AJE, Esquivias O, Coines J, Rovira C, Nidetzky B. Enzymatische C4-Epimerisierung von UDP-Glucuronsäure: präzise gesteuerte Rotation eines transienten 4-Ketointermediats für eine invertierende Reaktion ohne Decarboxylierung. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 135:e202211937. [PMID: 38515538 PMCID: PMC10952283 DOI: 10.1002/ange.202211937] [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: 08/12/2022] [Indexed: 03/23/2024]
Abstract
AbstractUDP‐Glucuronsäure(UDP‐GlcA)‐4‐Epimerase repräsentiert eine wichtige Fragestellung in der Enzymkatalyse: die Balance zwischen konformativer Flexibilität und genauer Positionierung. Das Enzym koordiniert die C4‐Oxidation des Substrats durch NAD+ mit der Rotation eines leicht decarboxylierbaren β‐Ketosäure‐Intermediats im aktiven Zentrum zur Ermöglichung der stereoinvertierenden Reduktion der Ketogruppe durch NADH. Wir zeigen hier die nur schwer erfassbare Rotationskoordinate des 4‐Ketointermediats. Distorsion des Zuckerrings in eine Boot‐Konformation erzeugt torsionale Mobilität in der Bindungstasche des Enzyms. Die Endpunkte der Rotation zeigen den 4‐Ketozucker in einer unverformten 4C1‐Sesselkonformation. Die äquatorial positionierte Carboxylatgruppe ist ungünstig für die 4‐Ketozucker‐Decarboxylierung. Varianten der Epimerase zeigen Decarboxylierung, wenn sie die Bindung mit der Carboxylatgruppe im entgegengesetzten Rotationsisomer des Substrats entfernen. R185A/D‐Substitutionen wandeln die Epimerase in UDP‐Xylose‐Synthasen um, welche UDP‐GlcA in stereospezifischen, konfigurationserhaltenden Reaktionen decarboxylieren.
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Affiliation(s)
- Annika J. E. Borg
- Institut für Biotechnologie und BioprozesstechnikTechnische Universität GrazPetersgasse 12/18010GrazÖsterreich
| | - Oriol Esquivias
- Department of Inorganic and Organic Chemistry (Section of Organic Chemistry)Institute of Computational and Theoretical Chemistry (IQTCUB)Martí i Franquès 108028BarcelonaSpanien
| | - Joan Coines
- Department of Inorganic and Organic Chemistry (Section of Organic Chemistry)Institute of Computational and Theoretical Chemistry (IQTCUB)Martí i Franquès 108028BarcelonaSpanien
- Derzeitige Adresse: Nostrum BiodiscoveryAv. De Josep Tarradellas, 8–1008029BarcelonaSpanien
| | - Carme Rovira
- Department of Inorganic and Organic Chemistry (Section of Organic Chemistry)Institute of Computational and Theoretical Chemistry (IQTCUB)Martí i Franquès 108028BarcelonaSpanien
- Institució Catalana de Recerca i Estudis Avançats (ICREA)Passeig Lluís Companys, 2308010BarcelonaSpanien
| | - Bernd Nidetzky
- Institut für Biotechnologie und BioprozesstechnikTechnische Universität GrazPetersgasse 12/18010GrazÖsterreich
- Austrian Center of Industrial Biotechnology (acib)Krenngasse 378010GrazÖsterreich
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9
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Borg AJE, Esquivias O, Coines J, Rovira C, Nidetzky B. Enzymatic C4-Epimerization of UDP-Glucuronic Acid: Precisely Steered Rotation of a Transient 4-Keto Intermediate for an Inverted Reaction without Decarboxylation. Angew Chem Int Ed Engl 2023; 62:e202211937. [PMID: 36308301 PMCID: PMC10107529 DOI: 10.1002/anie.202211937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 10/03/2022] [Accepted: 10/26/2022] [Indexed: 11/06/2022]
Abstract
UDP-glucuronic acid (UDP-GlcA) 4-epimerase illustrates an important problem regarding enzyme catalysis: balancing conformational flexibility with precise positioning. The enzyme coordinates the C4-oxidation of the substrate by NAD+ and rotation of a decarboxylation-prone β-keto acid intermediate in the active site, enabling stereoinverting reduction of the keto group by NADH. We reveal the elusive rotational landscape of the 4-keto intermediate. Distortion of the sugar ring into boat conformations induces torsional mobility in the enzyme's binding pocket. The rotational endpoints show that the 4-keto sugar has an undistorted 4 C1 chair conformation. The equatorially placed carboxylate group disfavors decarboxylation of the 4-keto sugar. Epimerase variants lead to decarboxylation upon removal of the binding interactions with the carboxylate group in the opposite rotational isomer of the substrate. Substitutions R185A/D convert the epimerase into UDP-xylose synthases that decarboxylate UDP-GlcA in stereospecific, configuration-retaining reactions.
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Affiliation(s)
- Annika J E Borg
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12/1, 8010, Graz, Austria
| | - Oriol Esquivias
- Department of Inorganic and Organic Chemistry (Section of Organic Chemistry), Institute of Computational and Theoretical Chemistry (IQTCUB), Martí i Franquès 1, 08028, Barcelona, Spain
| | - Joan Coines
- Department of Inorganic and Organic Chemistry (Section of Organic Chemistry), Institute of Computational and Theoretical Chemistry (IQTCUB), Martí i Franquès 1, 08028, Barcelona, Spain.,Present address: Nostrum Biodiscovery, Av. De Josep Tarradellas, 8-10, 08029, Barcelona, Spain
| | - Carme Rovira
- Department of Inorganic and Organic Chemistry (Section of Organic Chemistry), Institute of Computational and Theoretical Chemistry (IQTCUB), Martí i Franquès 1, 08028, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys, 23, 08010, Barcelona, Spain
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12/1, 8010, Graz, Austria.,Austrian Center of Industrial Biotechnology (acib), Krenngasse 37, 8010, Graz, Austria
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10
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Kumar A, DeGregorio N, Ricard T, Iyengar SS. Graph-Theoretic Molecular Fragmentation for Potential Surfaces Leads Naturally to a Tensor Network Form and Allows Accurate and Efficient Quantum Nuclear Dynamics. J Chem Theory Comput 2022; 18:7243-7259. [PMID: 36332133 DOI: 10.1021/acs.jctc.2c00484] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Molecular fragmentation methods have revolutionized quantum chemistry. Here, we use a graph-theoretically generated molecular fragmentation method, to obtain accurate and efficient representations for multidimensional potential energy surfaces and the quantum time-evolution operator, which plays a critical role in quantum chemical dynamics. In doing so, we find that the graph-theoretic fragmentation approach naturally reduces the potential portion of the time-evolution operator into a tensor network that contains a stream of coupled lower-dimensional propagation steps to potentially achieve quantum dynamics with reduced complexity. Furthermore, the fragmentation approach used here has previously been shown to allow accurate and efficient computation of post-Hartree-Fock electronic potential energy surfaces, which in many cases has been shown to be at density functional theory cost. Thus, by combining the advantages of molecular fragmentation with the tensor network formalism, the approach yields an on-the-fly quantum dynamics scheme where both the electronic potential calculation and nuclear propagation portion are enormously simplified through a single stroke. The method is demonstrated by computing approximations to the propagator and to potential surfaces for a set of coupled nuclear dimensions within a protonated water wire problem exhibiting the Grotthuss mechanism of proton transport. In all cases, our approach has been shown to reduce the complexity of representing the quantum propagator, and by extension action of the propagator on an initial wavepacket, by several orders, with minimal loss in accuracy.
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Affiliation(s)
- Anup Kumar
- Department of Chemistry, and the Indiana University Quantum Science and Engineering Center (IU-QSEC), Indiana University, Bloomington, Indiana 47405, United States
| | - Nicole DeGregorio
- Department of Chemistry, and the Indiana University Quantum Science and Engineering Center (IU-QSEC), Indiana University, Bloomington, Indiana 47405, United States
| | - Timothy Ricard
- Department of Chemistry, and the Indiana University Quantum Science and Engineering Center (IU-QSEC), Indiana University, Bloomington, Indiana 47405, United States
| | - Srinivasan S Iyengar
- Department of Chemistry, and the Indiana University Quantum Science and Engineering Center (IU-QSEC), Indiana University, Bloomington, Indiana 47405, United States
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11
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Tajoddin NN, Konermann L. Structural Dynamics of a Thermally Stressed Monoclonal Antibody Characterized by Temperature-Dependent H/D Exchange Mass Spectrometry. Anal Chem 2022; 94:15499-15509. [DOI: 10.1021/acs.analchem.2c03931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Nastaran N. Tajoddin
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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12
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Yabukarski F, Doukov T, Pinney MM, Biel JT, Fraser JS, Herschlag D. Ensemble-function relationships to dissect mechanisms of enzyme catalysis. SCIENCE ADVANCES 2022; 8:eabn7738. [PMID: 36240280 PMCID: PMC9565801 DOI: 10.1126/sciadv.abn7738] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 08/30/2022] [Indexed: 05/27/2023]
Abstract
Decades of structure-function studies have established our current extensive understanding of enzymes. However, traditional structural models are snapshots of broader conformational ensembles of interchanging states. We demonstrate the need for conformational ensembles to understand function, using the enzyme ketosteroid isomerase (KSI) as an example. Comparison of prior KSI cryogenic x-ray structures suggested deleterious mutational effects from a misaligned oxyanion hole catalytic residue. However, ensemble information from room-temperature x-ray crystallography, combined with functional studies, excluded this model. Ensemble-function analyses can deconvolute effects from altering the probability of occupying a state (P-effects) and changing the reactivity of each state (k-effects); our ensemble-function analyses revealed functional effects arising from weakened oxyanion hole hydrogen bonding and substrate repositioning within the active site. Ensemble-function studies will have an integral role in understanding enzymes and in meeting the future goals of a predictive understanding of enzyme catalysis and engineering new enzymes.
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Affiliation(s)
- Filip Yabukarski
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
| | - Tzanko Doukov
- Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Margaux M. Pinney
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
| | - Justin T. Biel
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - James S. Fraser
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Daniel Herschlag
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
- Stanford ChEM-H, Stanford University, Stanford, CA 94305, USA
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13
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Blazeck J, Karamitros CS, Ford K, Somody C, Qerqez A, Murray K, Burkholder NT, Marshall N, Sivakumar A, Lu WC, Tan B, Lamb C, Tanno Y, Siddiqui MY, Ashoura N, Coma S, Zhang XM, McGovern K, Kumada Y, Zhang YJ, Manfredi M, Johnson KA, D’Arcy S, Stone E, Georgiou G. Bypassing evolutionary dead ends and switching the rate-limiting step of a human immunotherapeutic enzyme. Nat Catal 2022; 5:952-967. [PMID: 36465553 PMCID: PMC9717613 DOI: 10.1038/s41929-022-00856-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 09/09/2022] [Indexed: 11/08/2022]
Abstract
The Trp metabolite kynurenine (KYN) accumulates in numerous solid tumours and mediates potent immunosuppression. Bacterial kynureninases (KYNases), which preferentially degrade kynurenine, can relieve immunosuppression in multiple cancer models, but immunogenicity concerns preclude their clinical use, while the human enzyme (HsKYNase) has very low activity for kynurenine and shows no therapeutic effect. Using fitness selections, we evolved a HsKYNase variant with 27-fold higher activity, beyond which exploration of >30 evolutionary trajectories involving the interrogation of >109 variants led to no further improvements. Introduction of two amino acid substitutions conserved in bacterial KYNases reduced enzyme fitness but potentiated rapid evolution of variants with ~500-fold improved activity and reversed substrate specificity, resulting in an enzyme capable of mediating strong anti-tumour effects in mice. Pre-steady-state kinetics revealed a switch in rate-determining step attributable to changes in both enzyme structure and conformational dynamics. Apart from its clinical significance, our work highlights how rationally designed substitutions can potentiate trajectories that overcome barriers in protein evolution.
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Affiliation(s)
- John Blazeck
- Department of Chemical Engineering, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Christos S. Karamitros
- Department of Chemical Engineering, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Kyle Ford
- Department of Chemical Engineering, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Catrina Somody
- Department of Chemical Engineering, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Ahlam Qerqez
- Department of Chemical Engineering, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Kyle Murray
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, Richardson, Texas, USA
| | - Nathaniel T. Burkholder
- Department of Molecular Biosciences, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Nicholas Marshall
- Department of Chemical Engineering, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Anirudh Sivakumar
- Department of Chemical Engineering, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Wei-Cheng Lu
- Department of Chemical Engineering, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Bing Tan
- Department of Chemical Engineering, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Candice Lamb
- Department of Chemical Engineering, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Yuri Tanno
- Department of Chemical Engineering, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Menna Y. Siddiqui
- Department of Chemical Engineering, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Norah Ashoura
- Department of Molecular Biosciences, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Silvia Coma
- Ikena Oncology, Cambridge, Massachusetts, USA
| | | | | | - Yoichi Kumada
- Department of Molecular Chemistry and Engineering, Kyoto Institute of Technology, Kyoto, Japan
| | - Yan Jessie Zhang
- Department of Molecular Biosciences, University of Texas at Austin (UT Austin), Austin, Texas, USA
- Institute for Cellular and Molecular Biology, The University of Texas at Austin (UT Austin), Austin, Texas, USA
| | | | - Kenneth A. Johnson
- Department of Molecular Biosciences, University of Texas at Austin (UT Austin), Austin, Texas, USA
| | - Sheena D’Arcy
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, Richardson, Texas, USA
| | - Everett Stone
- Department of Molecular Biosciences, University of Texas at Austin (UT Austin), Austin, Texas, USA
- Institute for Cellular and Molecular Biology, The University of Texas at Austin (UT Austin), Austin, Texas, USA
- Department of Oncology, University of Texas Dell Medical School, LiveSTRONG Cancer Institutes, Austin, Texas, USA
| | - George Georgiou
- Department of Chemical Engineering, University of Texas at Austin (UT Austin), Austin, Texas, USA
- Department of Molecular Biosciences, University of Texas at Austin (UT Austin), Austin, Texas, USA
- Institute for Cellular and Molecular Biology, The University of Texas at Austin (UT Austin), Austin, Texas, USA
- Department of Oncology, University of Texas Dell Medical School, LiveSTRONG Cancer Institutes, Austin, Texas, USA
- Department of Biomedical Engineering, University of Texas at Austin (UT Austin), Austin, TX, USA
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14
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Gao S, Klinman JP. Functional roles of enzyme dynamics in accelerating active site chemistry: Emerging techniques and changing concepts. Curr Opin Struct Biol 2022; 75:102434. [PMID: 35872562 PMCID: PMC9901422 DOI: 10.1016/j.sbi.2022.102434] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/15/2022] [Accepted: 06/21/2022] [Indexed: 02/08/2023]
Abstract
With the growing acceptance of the contribution of protein conformational ensembles to enzyme catalysis and regulation, research in the field of protein dynamics has shifted toward an understanding of the atomistic properties of protein dynamical networks and the mechanisms and time scales that control such behavior. A full description of an enzymatic reaction coordinate is expected to extend beyond the active site and include site-specific networks that communicate with the protein/water interface. Advances in experimental tools for the spatial resolution of thermal activation pathways are being complemented by biophysical methods for visualizing dynamics in real time. An emerging multidimensional model integrates the impacts of bound substrate/effector on the distribution of protein substates that are in rapid equilibration near room temperature with reaction-specific protein embedded heat transfer conduits.
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Affiliation(s)
- Shuaihua Gao
- Department of Chemistry, University of California, Berkeley, CA, 94720, United States; California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, United States. https://twitter.com/S_H_Gao
| | - Judith P Klinman
- Department of Chemistry, University of California, Berkeley, CA, 94720, United States; California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, United States; Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, United States.
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15
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Rapp C, Nidetzky B. Hydride Transfer Mechanism of Enzymatic Sugar Nucleotide C2 Epimerization Probed with a Loose-Fit CDP-Glucose Substrate. ACS Catal 2022; 12:6816-6830. [PMID: 35747200 PMCID: PMC9207888 DOI: 10.1021/acscatal.2c00257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 05/12/2022] [Indexed: 11/29/2022]
Abstract
![]()
Transient oxidation–reduction
through hydride transfer with
tightly bound NAD coenzyme is used by a large class of sugar nucleotide
epimerases to promote configurational inversion of carbon stereocenters
in carbohydrate substrates. A requirement for the epimerases to coordinate
hydride abstraction and re-addition with substrate rotation in the
binding pocket poses a challenge for dynamical protein conformational
selection linked to enzyme catalysis. Here, we studied the thermophilic
C2 epimerase from Thermodesulfatator atlanticus (TaCPa2E) in combination with a slow CDP-glucose
substrate (kcat ≈ 1.0 min–1; 60 °C) to explore the sensitivity of the enzymatic hydride
transfer toward environmental fluctuations affected by temperature
(20–80 °C). We determined noncompetitive primary kinetic
isotope effects (KIE) due to 2H at the glucose C2 and showed
that a normal KIE on the kcat (Dkcat) reflects isotope sensitivity of
the hydrogen abstraction to enzyme-NAD+ in a rate-limiting
transient oxidation. The Dkcat peaked at 40 °C was 6.1 and decreased to 2.1 at low (20 °C)
and 3.3 at high temperature (80 °C). The temperature profiles
for kcat with the 1H and 2H substrate showed a decrease in the rate below a dynamically
important breakpoint (∼40 °C), suggesting an equilibrium
shift to an impaired conformational landscape relevant for catalysis
in the low-temperature region. Full Marcus-like model fits of the
rate and KIE profiles provided evidence for a high-temperature reaction
via low-frequency conformational sampling associated with a broad
distribution of hydride donor–acceptor distances (long-distance
population centered at 3.31 ± 0.02 Å), only poorly suitable
for quantum mechanical tunneling. Collectively, dynamical characteristics
of TaCPa2E-catalyzed hydride transfer during transient
oxidation of CDP-glucose reveal important analogies to mechanistically
simpler enzymes such as alcohol dehydrogenase and dihydrofolate reductase.
A loose-fit substrate (in TaCPa2E) resembles structural
variants of these enzymes by extensive dynamical sampling to balance
conformational flexibility and catalytic efficiency.
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Affiliation(s)
- Christian Rapp
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 10-12/1, 8010 Graz, Austria
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 10-12/1, 8010 Graz, Austria
- Austrian Centre of Industrial Biotechnology (ACIB), Petersgasse 14, 8010 Graz, Austria
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16
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Romero-Rivera A, Corbella M, Parracino A, Patrick WM, Kamerlin SCL. Complex Loop Dynamics Underpin Activity, Specificity, and Evolvability in the (βα) 8 Barrel Enzymes of Histidine and Tryptophan Biosynthesis. JACS AU 2022; 2:943-960. [PMID: 35557756 PMCID: PMC9088769 DOI: 10.1021/jacsau.2c00063] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 03/16/2022] [Accepted: 03/18/2022] [Indexed: 05/16/2023]
Abstract
Enzymes are conformationally dynamic, and their dynamical properties play an important role in regulating their specificity and evolvability. In this context, substantial attention has been paid to the role of ligand-gated conformational changes in enzyme catalysis; however, such studies have focused on tremendously proficient enzymes such as triosephosphate isomerase and orotidine 5'-monophosphate decarboxylase, where the rapid (μs timescale) motion of a single loop dominates the transition between catalytically inactive and active conformations. In contrast, the (βα)8-barrels of tryptophan and histidine biosynthesis, such as the specialist isomerase enzymes HisA and TrpF, and the bifunctional isomerase PriA, are decorated by multiple long loops that undergo conformational transitions on the ms (or slower) timescale. Studying the interdependent motions of multiple slow loops, and their role in catalysis, poses a significant computational challenge. This work combines conventional and enhanced molecular dynamics simulations with empirical valence bond simulations to provide rich details of the conformational behavior of the catalytic loops in HisA, PriA, and TrpF, and the role of their plasticity in facilitating bifunctionality in PriA and evolved HisA variants. In addition, we demonstrate that, similar to other enzymes activated by ligand-gated conformational changes, loops 3 and 4 of HisA and PriA act as gripper loops, facilitating the isomerization of the large bulky substrate ProFAR, albeit now on much slower timescales. This hints at convergent evolution on these different (βα)8-barrel scaffolds. Finally, our work reemphasizes the potential of engineering loop dynamics as a tool to artificially manipulate the catalytic repertoire of TIM-barrel proteins.
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Affiliation(s)
- Adrian Romero-Rivera
- Department
of Chemistry—BMC, Uppsala University, BMC Box 576, S-751 23 Uppsala, Sweden
| | - Marina Corbella
- Department
of Chemistry—BMC, Uppsala University, BMC Box 576, S-751 23 Uppsala, Sweden
| | - Antonietta Parracino
- Department
of Chemistry—BMC, Uppsala University, BMC Box 576, S-751 23 Uppsala, Sweden
| | - Wayne M. Patrick
- Centre
for Biodiscovery, School of Biological Sciences, Victoria University of Wellington, 6012 Wellington, New Zealand
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17
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Schmidt-Engler JM, von Berg S, Bredenbeck J. Temperature-Dependent Low-Frequency Modes in the Active Site of Bovine Carbonic Anhydrase II Probed by 2D-IR Spectroscopy. J Phys Chem Lett 2021; 12:7777-7782. [PMID: 34374547 DOI: 10.1021/acs.jpclett.1c01453] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Enzyme catalysis achieves tremendous rate accelerations. Enzyme reaction centers provide a constraint geometry that preferentially binds an activated form of the substrate and thus lowers the energy barrier. However, this transition state picture neglects the flexibility of proteins and its role in enzymatic catalysis. Especially for proton transfer reactions, it has been suggested that motions of the protein modulate the donor-acceptor distance and prepare a tunneling-ready state. We report the detection of frequency fluctuations of an azide anion (N3-) bound in the active site of the protein carbonic anhydrase II, where a low-frequency mode of the protein has been proposed to facilitate proton transfer over two water molecules during the catalyzed reaction. 2D-IR spectroscopy resolves an underdamped low-frequency mode at about 1 THz (30 cm-1). We find its frequency to be viscosity- and temperature-dependent and to decrease by 6 cm-1 between 230 and 320 K, reporting the softening of the mode's potential.
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Affiliation(s)
- Julian M Schmidt-Engler
- Institute of Biophysics, Johann Wolfgang Goethe-University, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany
| | - Sarah von Berg
- Institute of Biophysics, Johann Wolfgang Goethe-University, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany
| | - Jens Bredenbeck
- Institute of Biophysics, Johann Wolfgang Goethe-University, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany
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18
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Rabe P, Kamps JJAG, Sutherlin KD, Linyard JDS, Aller P, Pham CC, Makita H, Clifton I, McDonough MA, Leissing TM, Shutin D, Lang PA, Butryn A, Brem J, Gul S, Fuller FD, Kim IS, Cheah MH, Fransson T, Bhowmick A, Young ID, O'Riordan L, Brewster AS, Pettinati I, Doyle M, Joti Y, Owada S, Tono K, Batyuk A, Hunter MS, Alonso-Mori R, Bergmann U, Owen RL, Sauter NK, Claridge TDW, Robinson CV, Yachandra VK, Yano J, Kern JF, Orville AM, Schofield CJ. X-ray free-electron laser studies reveal correlated motion during isopenicillin N synthase catalysis. SCIENCE ADVANCES 2021; 7:eabh0250. [PMID: 34417180 PMCID: PMC8378823 DOI: 10.1126/sciadv.abh0250] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 06/29/2021] [Indexed: 05/23/2023]
Abstract
Isopenicillin N synthase (IPNS) catalyzes the unique reaction of l-δ-(α-aminoadipoyl)-l-cysteinyl-d-valine (ACV) with dioxygen giving isopenicillin N (IPN), the precursor of all natural penicillins and cephalosporins. X-ray free-electron laser studies including time-resolved crystallography and emission spectroscopy reveal how reaction of IPNS:Fe(II):ACV with dioxygen to yield an Fe(III) superoxide causes differences in active site volume and unexpected conformational changes that propagate to structurally remote regions. Combined with solution studies, the results reveal the importance of protein dynamics in regulating intermediate conformations during conversion of ACV to IPN. The results have implications for catalysis by multiple IPNS-related oxygenases, including those involved in the human hypoxic response, and highlight the power of serial femtosecond crystallography to provide insight into long-range enzyme dynamics during reactions presently impossible for nonprotein catalysts.
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Affiliation(s)
- Patrick Rabe
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Jos J A G Kamps
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA, UK
| | - Kyle D Sutherlin
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - James D S Linyard
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Pierre Aller
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA, UK
| | - Cindy C Pham
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Hiroki Makita
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Ian Clifton
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Michael A McDonough
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Thomas M Leissing
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Denis Shutin
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Pauline A Lang
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Agata Butryn
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA, UK
| | - Jürgen Brem
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Sheraz Gul
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Franklin D Fuller
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - In-Sik Kim
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Mun Hon Cheah
- Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, SE 751 20 Uppsala, Sweden
| | - Thomas Fransson
- Interdisciplinary Center for Scientific Computing, University of Heidelberg, 69120 Heidelberg, Germany
| | - Asmit Bhowmick
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Iris D Young
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, 600 16th Street, San Francisco, CA 94158, USA
| | - Lee O'Riordan
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Aaron S Brewster
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Ilaria Pettinati
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Margaret Doyle
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Yasumasa Joti
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Shigeki Owada
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Kensuke Tono
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Alexander Batyuk
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Mark S Hunter
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Roberto Alonso-Mori
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Uwe Bergmann
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, WI 53706, USA
| | - Robin L Owen
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
| | - Nicholas K Sauter
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Timothy D W Claridge
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Carol V Robinson
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Vittal K Yachandra
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Junko Yano
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Jan F Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA.
| | - Allen M Orville
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK.
- Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA, UK
| | - Christopher J Schofield
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK.
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19
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Singh P, Vandemeulebroucke A, Li J, Schulenburg C, Fortunato G, Kohen A, Hilvert D, Cheatum CM. Evolution of the Chemical Step in Enzyme Catalysis. ACS Catal 2021. [DOI: 10.1021/acscatal.1c00442] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Priyanka Singh
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | | | - Jiayue Li
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Cindy Schulenburg
- Laboratory of Organic Chemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Gabriel Fortunato
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Amnon Kohen
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Donald Hilvert
- Laboratory of Organic Chemistry, ETH Zurich, 8093 Zurich, Switzerland
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20
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Leisinger F, Miarzlou DA, Seebeck FP. Non-Coordinative Binding of O 2 at the Active Center of a Copper-Dependent Enzyme. Angew Chem Int Ed Engl 2021; 60:6154-6159. [PMID: 33245183 DOI: 10.1002/anie.202014981] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Indexed: 12/28/2022]
Abstract
Molecular oxygen (O2 ) is a sustainable oxidation reagent. O2 is strongly oxidizing but kinetically stable and its final reaction product is water. For these reasons learning how to activate O2 and how to steer its reactivity along desired reaction pathways is a longstanding challenge in chemical research.[1] Activation of ground-state diradical O2 can occur either via conversion to singlet oxygen or by one-electron reduction to superoxide. Many enzymes facilitate activation of O2 by direct fomation of a metal-oxygen coordination complex concomitant with inner sphere electron transfer. The formylglycine generating enzyme (FGE) is an unusual mononuclear copper enzyme that appears to follow a different strategy. Atomic-resolution crystal structures of the precatalytic complex of FGE demonstrate that this enzyme binds O2 juxtaposed, but not coordinated to the catalytic CuI . Isostructural complexes that contain AgI instead of CuI or nitric oxide instead of O2 confirm that formation of the initial oxygenated complex of FGE does not depend on redox activity. A stepwise mechanism that decouples binding and activation of O2 is unprecedented for metal-dependent oxidases, but is reminiscent of flavin-dependent enzymes.
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Affiliation(s)
- Florian Leisinger
- Department of Chemistry, University of Basel, Mattenstrasse 24a, 4002, Basel, Switzerland
| | - Dzmitry A Miarzlou
- Department of Chemistry, University of Basel, Mattenstrasse 24a, 4002, Basel, Switzerland
| | - Florian P Seebeck
- Department of Chemistry, University of Basel, Mattenstrasse 24a, 4002, Basel, Switzerland
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21
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Leisinger F, Miarzlou DA, Seebeck FP. Non‐Coordinative Binding of O
2
at the Active Center of a Copper‐Dependent Enzyme. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202014981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Florian Leisinger
- Department of Chemistry University of Basel Mattenstrasse 24a 4002 Basel Switzerland
| | - Dzmitry A. Miarzlou
- Department of Chemistry University of Basel Mattenstrasse 24a 4002 Basel Switzerland
| | - Florian P. Seebeck
- Department of Chemistry University of Basel Mattenstrasse 24a 4002 Basel Switzerland
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22
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Thompson EJ, Paul A, Iavarone AT, Klinman JP. Identification of Thermal Conduits That Link the Protein-Water Interface to the Active Site Loop and Catalytic Base in Enolase. J Am Chem Soc 2021; 143:785-797. [PMID: 33395523 DOI: 10.1021/jacs.0c09423] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We report here on the salient role of protein mobility in accessing conformational landscapes that enable efficient enzyme catalysis. We are focused on yeast enolase, a highly conserved lyase with a TIM barrel domain and catalytic loop, as part of a larger study of the relationship of site selective protein motions to chemical reactivity within superfamilies. Enthalpically hindered variants were developed by replacement of a conserved hydrophobic side chain (Leu 343) with smaller side chains. Leu343 is proximal to the active site base in enolase, and comparative pH rate profiles for the valine and alanine variants indicate a role for side chain hydrophobicity in tuning the pKa of the catalytic base. However, the magnitude of a substrate deuterium isotope effect is almost identical for wild-type (WT) and Leu343Ala, supporting an unchanged rate-determining proton abstraction step. The introduced hydrophobic side chains at position 343 lead to a discontinuous break in both activity and activation energy as a function of side chain volume. Hydrogen-deuterium exchange mass spectrometry (HDX-MS) experiments were performed as a function of time and temperature for WT and Leu343Ala, and provide a spatially resolved map of changes in protein flexibility following mutation. Impacts on protein flexibility are localized to specific networks that arise at the protein-solvent interface and terminate in a loop that has been shown by X-ray crystallography to close over the active site. These interrelated effects are discussed in the context of long-range, solvent-accessible and thermally activated networks that play key roles in tuning the precise distances and interactions among reactants.
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Affiliation(s)
- Emily J Thompson
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, United States
| | - Adhayana Paul
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, United States
| | - Anthony T Iavarone
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, United States
| | - Judith P Klinman
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, United States.,Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, United States
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23
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Abstract
This review examines low-frequency vibrational modes of proteins and their coupling to enzyme catalytic sites. That protein motions are critical to enzyme function is clear, but the kinds of motions present in proteins and how they are involved in function remain unclear. Several models of enzyme-catalyzed reaction suggest that protein dynamics may be involved in the chemical step of the catalyzed reaction, but the evidence in support of such models is indirect. Spectroscopic studies of low-frequency protein vibrations consistently show that there are underdamped modes of the protein with frequencies in the tens of wavenumbers where overdamped behavior would be expected. Recent studies even show that such underdamped vibrations modulate enzyme active sites. These observations suggest that increasingly sophisticated spectroscopic methods will be able to unravel the link between low-frequency protein vibrations and enzyme function.
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24
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Assessment of enzyme active site positioning and tests of catalytic mechanisms through X-ray-derived conformational ensembles. Proc Natl Acad Sci U S A 2020; 117:33204-33215. [PMID: 33376217 DOI: 10.1073/pnas.2011350117] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
How enzymes achieve their enormous rate enhancements remains a central question in biology, and our understanding to date has impacted drug development, influenced enzyme design, and deepened our appreciation of evolutionary processes. While enzymes position catalytic and reactant groups in active sites, physics requires that atoms undergo constant motion. Numerous proposals have invoked positioning or motions as central for enzyme function, but a scarcity of experimental data has limited our understanding of positioning and motion, their relative importance, and their changes through the enzyme's reaction cycle. To examine positioning and motions and test catalytic proposals, we collected "room temperature" X-ray crystallography data for Pseudomonas putida ketosteroid isomerase (KSI), and we obtained conformational ensembles for this and a homologous KSI from multiple PDB crystal structures. Ensemble analyses indicated limited change through KSI's reaction cycle. Active site positioning was on the 1- to 1.5-Å scale, and was not exceptional compared to noncatalytic groups. The KSI ensembles provided evidence against catalytic proposals invoking oxyanion hole geometric discrimination between the ground state and transition state or highly precise general base positioning. Instead, increasing or decreasing positioning of KSI's general base reduced catalysis, suggesting optimized Ångstrom-scale conformational heterogeneity that allows KSI to efficiently catalyze multiple reaction steps. Ensemble analyses of surrounding groups for WT and mutant KSIs provided insights into the forces and interactions that allow and limit active-site motions. Most generally, this ensemble perspective extends traditional structure-function relationships, providing the basis for a new era of "ensemble-function" interrogation of enzymes.
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25
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Gao S, Thompson EJ, Barrow SL, Zhang W, Iavarone AT, Klinman JP. Hydrogen-Deuterium Exchange within Adenosine Deaminase, a TIM Barrel Hydrolase, Identifies Networks for Thermal Activation of Catalysis. J Am Chem Soc 2020; 142:19936-19949. [PMID: 33181018 DOI: 10.1021/jacs.0c07866] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Proteins are intrinsically flexible macromolecules that undergo internal motions with time scales spanning femtoseconds to milliseconds. These fluctuations are implicated in the optimization of reaction barriers for enzyme catalyzed reactions. Time, temperature, and mutation dependent hydrogen-deuterium exchange coupled to mass spectrometry (HDX-MS) has been previously employed to identify spatially resolved, catalysis-linked dynamical regions of enzymes. We now extend this technique to pursue the correlation of protein flexibility and chemical reactivity within the diverse and widespread TIM barrel proteins, targeting murine adenosine deaminase (mADA) that catalyzes the irreversible deamination of adenosine to inosine and ammonia. Following a structure-function analysis of rate and activation energy for a series of mutations at a second sphere phenylalanine positioned in proximity to the bound substrate, the catalytically impaired Phe61Ala with an elevated activation energy (Ea = 7.5 kcal/mol) and the wild type (WT) mADA (Ea = 5.0 kcal/mol) were selected for HDX-MS experiments. The rate constants and activation energies of HDX for peptide segments are quantified and used to assess mutation-dependent changes in local and distal motions. Analyses reveal that approximately 50% of the protein sequence of Phe61Ala displays significant changes in the temperature dependence of HDX behaviors, with the dominant change being an increase in protein flexibility. Utilizing Phe61Ile, which displays the same activation energy for kcat as WT, as a control, we were able to further refine the HDX analysis, highlighting the regions of mADA that are altered in a functionally relevant manner. A map is constructed that illustrates the regions of protein that are proposed to be essential for the thermal optimization of active site configurations that dominate reaction barrier crossings in the native enzyme.
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Affiliation(s)
| | | | | | - Wenju Zhang
- David R. Cheriton School of Computer Science, University of Waterloo, Waterloo, ON N2L 3G1, Canada
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26
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Beikzadeh M, Latham MP. The dynamic nature of the Mre11-Rad50 DNA break repair complex. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 163:14-22. [PMID: 33121960 DOI: 10.1016/j.pbiomolbio.2020.10.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 10/02/2020] [Accepted: 10/23/2020] [Indexed: 01/18/2023]
Abstract
The Mre11-Rad50-Nbs1/Xrs2 protein complex plays a pivotal role in the detection and repair of DNA double strand breaks. Through traditional and emerging structural biology techniques, various functional structural states of this complex have been visualized; however, relatively little is known about the transitions between these states. Indeed, it is these structural transitions that are important for Mre11-Rad50-mediated DNA unwinding at a break and the activation of downstream repair signaling events. Here, we present a brief overview of the current understanding of the structure of the core Mre11-Rad50 complex. We then highlight our recent studies emphasizing the contributions of solution state NMR spectroscopy and other biophysical techniques in providing insight into the structures and dynamics associated with Mre11-Rad50 functions.
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Affiliation(s)
- Mahtab Beikzadeh
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, USA
| | - Michael P Latham
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, USA.
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27
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Das A, Hessin C, Ren Y, Desage-El Murr M. Biological concepts for catalysis and reactivity: empowering bioinspiration. Chem Soc Rev 2020; 49:8840-8867. [PMID: 33107878 DOI: 10.1039/d0cs00914h] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Biological systems provide attractive reactivity blueprints for the design of challenging chemical transformations. Emulating the operating mode of natural systems may however not be so easy and direct translation of structural observations does not always afford the anticipated efficiency. Metalloenzymes rely on earth-abundant metals to perform an incredibly wide range of chemical transformations. To do so, enzymes in general have evolved tools and tricks to enable control of such reactivity. The underlying concepts related to these tools are usually well-known to enzymologists and bio(inorganic) chemists but may be a little less familiar to organometallic chemists. So far, the field of bioinspired catalysis has greatly focused on the coordination sphere and electronic effects for the design of functional enzyme models but might benefit from a paradigm shift related to recent findings in biological systems. The goal of this review is to bring these fields closer together as this could likely result in the development of a new generation of highly efficient bioinspired systems. This contribution covers the fields of redox-active ligands, entatic state reactivity, energy conservation through electron bifurcation, and quantum tunneling for C-H activation.
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Affiliation(s)
- Agnideep Das
- Université de Strasbourg, Institut de Chimie, UMR CNRS 7177, 67000 Strasbourg, France.
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28
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Srinivas V, Banerjee R, Lebrette H, Jones JC, Aurelius O, Kim IS, Pham CC, Gul S, Sutherlin KD, Bhowmick A, John J, Bozkurt E, Fransson T, Aller P, Butryn A, Bogacz I, Simon P, Keable S, Britz A, Tono K, Kim KS, Park SY, Lee SJ, Park J, Alonso-Mori R, Fuller FD, Batyuk A, Brewster AS, Bergmann U, Sauter NK, Orville AM, Yachandra VK, Yano J, Lipscomb JD, Kern J, Högbom M. High-Resolution XFEL Structure of the Soluble Methane Monooxygenase Hydroxylase Complex with its Regulatory Component at Ambient Temperature in Two Oxidation States. J Am Chem Soc 2020; 142:14249-14266. [PMID: 32683863 PMCID: PMC7457426 DOI: 10.1021/jacs.0c05613] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Soluble methane monooxygenase (sMMO) is a multicomponent metalloenzyme that catalyzes the conversion of methane to methanol at ambient temperature using a nonheme, oxygen-bridged dinuclear iron cluster in the active site. Structural changes in the hydroxylase component (sMMOH) containing the diiron cluster caused by complex formation with a regulatory component (MMOB) and by iron reduction are important for the regulation of O2 activation and substrate hydroxylation. Structural studies of metalloenzymes using traditional synchrotron-based X-ray crystallography are often complicated by partial X-ray-induced photoreduction of the metal center, thereby obviating determination of the structure of the enzyme in pure oxidation states. Here, microcrystals of the sMMOH:MMOB complex from Methylosinus trichosporium OB3b were serially exposed to X-ray free electron laser (XFEL) pulses, where the ≤35 fs duration of exposure of an individual crystal yields diffraction data before photoreduction-induced structural changes can manifest. Merging diffraction patterns obtained from thousands of crystals generates radiation damage-free, 1.95 Å resolution crystal structures for the fully oxidized and fully reduced states of the sMMOH:MMOB complex for the first time. The results provide new insight into the manner by which the diiron cluster and the active site environment are reorganized by the regulatory protein component in order to enhance the steps of oxygen activation and methane oxidation. This study also emphasizes the value of XFEL and serial femtosecond crystallography (SFX) methods for investigating the structures of metalloenzymes with radiation sensitive metal active sites.
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Affiliation(s)
- Vivek Srinivas
- Department of Biochemistry and Biophysics, Stockholm University, Arrhenius Laboratories for Natural Sciences, Stockholm, Sweden
| | - Rahul Banerjee
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55391 U.S.A
| | - Hugo Lebrette
- Department of Biochemistry and Biophysics, Stockholm University, Arrhenius Laboratories for Natural Sciences, Stockholm, Sweden
| | - Jason C. Jones
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55391 U.S.A
| | - Oskar Aurelius
- Department of Biochemistry and Biophysics, Stockholm University, Arrhenius Laboratories for Natural Sciences, Stockholm, Sweden
| | - In-Sik Kim
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 U.S.A
| | - Cindy C. Pham
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 U.S.A
| | - Sheraz Gul
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 U.S.A
| | - Kyle D. Sutherlin
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 U.S.A
| | - Asmit Bhowmick
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 U.S.A
| | - Juliane John
- Department of Biochemistry and Biophysics, Stockholm University, Arrhenius Laboratories for Natural Sciences, Stockholm, Sweden
| | - Esra Bozkurt
- Department of Biochemistry and Biophysics, Stockholm University, Arrhenius Laboratories for Natural Sciences, Stockholm, Sweden
| | - Thomas Fransson
- Interdisciplinary Center for Scientific Computing, University of Heidelberg, 69120 Heidelberg, Germany
| | - Pierre Aller
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Agata Butryn
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Isabel Bogacz
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 U.S.A
| | - Philipp Simon
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 U.S.A
| | - Stephen Keable
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 U.S.A
| | - Alexander Britz
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025 U.S.A
| | - Kensuke Tono
- Japan Synchrotron Radiation Research Institute, Sayo-gun 679 5198, Japan
| | - Kyung Sook Kim
- Pohang Accelerator Laboratory, Gyeongsangbuk-do 37673, South Korea
| | - Sang-Youn Park
- Pohang Accelerator Laboratory, Gyeongsangbuk-do 37673, South Korea
| | - Sang Jae Lee
- Pohang Accelerator Laboratory, Gyeongsangbuk-do 37673, South Korea
| | - Jaehyun Park
- Pohang Accelerator Laboratory, Gyeongsangbuk-do 37673, South Korea
| | - Roberto Alonso-Mori
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025 U.S.A
| | - Franklin D. Fuller
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025 U.S.A
| | - Alexander Batyuk
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025 U.S.A
| | - Aaron S. Brewster
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 U.S.A
| | - Uwe Bergmann
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California, 94025 U.S.A
| | - Nicholas K. Sauter
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 U.S.A
| | - Allen M. Orville
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
- Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire, OX11 0FA, UK
| | - Vittal K. Yachandra
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 U.S.A
| | - Junko Yano
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 U.S.A
| | - John D. Lipscomb
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55391 U.S.A
| | - Jan Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 U.S.A
| | - Martin Högbom
- Department of Biochemistry and Biophysics, Stockholm University, Arrhenius Laboratories for Natural Sciences, Stockholm, Sweden
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29
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Crean RM, Gardner JM, Kamerlin SCL. Harnessing Conformational Plasticity to Generate Designer Enzymes. J Am Chem Soc 2020; 142:11324-11342. [PMID: 32496764 PMCID: PMC7467679 DOI: 10.1021/jacs.0c04924] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Indexed: 02/08/2023]
Abstract
Recent years have witnessed an explosion of interest in understanding the role of conformational dynamics both in the evolution of new enzymatic activities from existing enzymes and in facilitating the emergence of enzymatic activity de novo on scaffolds that were previously non-catalytic. There are also an increasing number of examples in the literature of targeted engineering of conformational dynamics being successfully used to alter enzyme selectivity and activity. Despite the obvious importance of conformational dynamics to both enzyme function and evolvability, many (although not all) computational design approaches still focus either on pure sequence-based approaches or on using structures with limited flexibility to guide the design. However, there exist a wide variety of computational approaches that can be (re)purposed to introduce conformational dynamics as a key consideration in the design process. Coupled with laboratory evolution and more conventional existing sequence- and structure-based approaches, these techniques provide powerful tools for greatly expanding the protein engineering toolkit. This Perspective provides an overview of evolutionary studies that have dissected the role of conformational dynamics in facilitating the emergence of novel enzymes, as well as advances in computational approaches that allow one to target conformational dynamics as part of enzyme design. Harnessing conformational dynamics in engineering studies is a powerful paradigm with which to engineer the next generation of designer biocatalysts.
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Affiliation(s)
- Rory M. Crean
- Department of Chemistry -
BMC, Uppsala University, Box 576, 751 23 Uppsala, Sweden
| | - Jasmine M. Gardner
- Department of Chemistry -
BMC, Uppsala University, Box 576, 751 23 Uppsala, Sweden
| | - Shina C. L. Kamerlin
- Department of Chemistry -
BMC, Uppsala University, Box 576, 751 23 Uppsala, Sweden
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30
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Rosenberg MM, Yao T, Patton GC, Redfield AG, Roberts MF, Hedstrom L. Enzyme-Substrate-Cofactor Dynamical Networks Revealed by High-Resolution Field Cycling Relaxometry. Biochemistry 2020; 59:2359-2370. [PMID: 32479091 PMCID: PMC8364753 DOI: 10.1021/acs.biochem.0c00212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The remarkable power and specificity of enzyme catalysis rely on the dynamic alignment of the enzyme, substrates, and cofactors, yet the role of dynamics has usually been approached from the perspective of the protein. We have been using an underappreciated NMR technique, subtesla high-resolution field cycling 31P NMR relaxometry, to investigate the dynamics of the enzyme-bound substrates and cofactor on guanosine-5'-monophosphate reductase (GMPR). GMPR forms two dead end, yet catalytically competent, complexes that mimic distinct steps in the catalytic cycle: E·IMP·NADP+ undergoes a partial hydride transfer reaction, while E·GMP·NADP+ undergoes a partial deamination reaction. A different cofactor conformation is required for each partial reaction. Here we report the effects of mutations designed to perturb cofactor conformation and ammonia binding with the goal of identifying the structural features that contribute to the distinct dynamic signatures of the hydride transfer and deamination complexes. These experiments suggest that Asp129 is a central cog in a dynamic network required for both hydride transfer and deamination. In contrast, Lys77 modulates the conformation and mobility of substrates and cofactors in a reaction-specific manner. Thr105 and Tyr318 are part of a deamination-specific dynamic network that includes the 2'-OH of GMP. These residues have comparatively little effect on the dynamic properties of the hydride transfer complex. These results further illustrate the potential of high-resolution field cycling NMR relaxometry for the investigation of ligand dynamics. In addition, exchange experiments indicate that NH3/NH4+ has a high affinity for the deamination complex but a low affinity for the hydride transfer complex, suggesting that the movement of ammonia may gate the cofactor conformational change. Collectively, these experiments reinforce the view that the enzyme, substrates, and cofactor are linked in intricate, reaction-specific, dynamic networks and demonstrate that distal portions of the substrates and cofactors are critical features in these networks.
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Affiliation(s)
- Masha M. Rosenberg
- Department of Biology, Brandeis University, MS009, 415 South St., Waltham MA 02453-9110 USA
| | - Tianjiong Yao
- Department of Biology, Brandeis University, MS009, 415 South St., Waltham MA 02453-9110 USA
| | - Gregory C. Patton
- Department of Biology, Brandeis University, MS009, 415 South St., Waltham MA 02453-9110 USA
| | - Alfred G. Redfield
- Department of Biochemistry, Brandeis University, MS009, 415 South Street, Waltham, MA 02453-9110 USA
| | - Mary F. Roberts
- Department of Chemistry, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467-9110 USA
| | - Lizbeth Hedstrom
- Department of Biology, Brandeis University, MS009, 415 South St., Waltham MA 02453-9110 USA
- Department of Chemistry, Brandeis University, 415 South Street, Waltham, MA 02453-3808 USA
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31
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Tajoddin NN, Konermann L. Analysis of Temperature-Dependent H/D Exchange Mass Spectrometry Experiments. Anal Chem 2020; 92:10058-10067. [DOI: 10.1021/acs.analchem.0c01828] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Nastaran N. Tajoddin
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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32
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Kim K, Plapp BV. Substitutions of Amino Acid Residues in the Substrate Binding Site of Horse Liver Alcohol Dehydrogenase Have Small Effects on the Structures but Significantly Affect Catalysis of Hydrogen Transfer. Biochemistry 2020; 59:862-879. [PMID: 31994873 DOI: 10.1021/acs.biochem.9b01074] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Previous studies showed that the L57F and F93W alcohol dehydrogenases catalyze the oxidation of benzyl alcohol with some quantum mechanical hydrogen tunneling, whereas the V203A enzyme has diminished tunneling. Here, steady-state kinetics for the L57F and F93W enzymes were studied, and microscopic rate constants for the ordered bi-bi mechanism were estimated from simulations of transient kinetics for the S48T, F93A, S48T/F93A, F93W, and L57F enzymes. Catalytic efficiencies for benzyl alcohol oxidation (V1/EtKb) vary over a range of ∼100-fold for the less active enzymes up to the L57F enzyme and are mostly associated with the binding of alcohol rather than the rate constants for hydride transfer. In contrast, catalytic efficiencies for benzaldehyde reduction (V2/EtKp) are ∼500-fold higher for the L57F enzyme than for the less active enzymes and are mostly associated with the rate constants for hydride transfer. Atomic-resolution structures (1.1 Å) for the F93W and L57F enzymes complexed with NAD+ and 2,3,4,5,6-pentafluorobenzyl alcohol or 2,2,2-trifluoroethanol are almost identical to previous structures for the wild-type, S48T, and V203A enzymes. Least-squares refinement with SHELXL shows that the nicotinamide ring is slightly strained in all complexes and that the apparent donor-acceptor distances from C4N of NAD to C7 of pentafluorobenzyl alcohol range from 3.28 to 3.49 Å (±0.02 Å) and are not correlated with the rate constants for hydride transfer or hydrogen tunneling. How the substitutions affect the dynamics of reorganization during hydrogen transfer and the extent of tunneling remain to be determined.
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Affiliation(s)
- Keehyuk Kim
- Department of Biochemistry , The University of Iowa , Iowa City , Iowa 52242 , United States
| | - Bryce V Plapp
- Department of Biochemistry , The University of Iowa , Iowa City , Iowa 52242 , United States
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33
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Karković Marković A, Jakobušić Brala C, Pilepić V, Uršić S. Hydrogen Tunnelling as a Probe of the Involvement of Water Vibrational Dynamics in Aqueous Chemistry? Molecules 2019; 25:E172. [PMID: 31906197 PMCID: PMC6983115 DOI: 10.3390/molecules25010172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 12/14/2019] [Accepted: 12/28/2019] [Indexed: 11/17/2022] Open
Abstract
Our study of tunnelling in proton-coupled electron transfer (PCET) oxidation of ascorbate with hexacyanoferrate(III) follows the insights obtained from ultrafast 2D IR spectroscopy and theoretical studies of the vibrational water dynamics that led to the proposal of the involvement of collective intermolecular excitonic vibrational water dynamics in aqueous chemistry. To test the proposal, the hydrogen tunnelling modulation observed in the PCET reaction studied in the presence of low concentrations of various partial hydrophobic solutes in the water reaction system has been analyzed in terms of the proposed involvement of the collective intermolecular vibrational water dynamics in activation process in the case. The strongly linear correlation between common tunnelling signatures, isotopic values of Arrhenius prefactor ratios ln AH/AD and isotopic differences in activation enthalpies ΔΔH‡ (H,D) observed in the process in fairly diluted water solutions containing various partial hydrophobic solutes (such as dioxane, acetonitrile, ethanol, and quaternary ammonium ions) points to the common physical origin of the phenomenon in all the cases. It is suggested that the phenomenon can be rooted in an interplay of delocalized collective intermolecular vibrational dynamics of water correlated with vibrations of the coupled transition configuration, where the donor-acceptor oscillations, the motions being to some degree along the reaction coordinate, lead to modulation of hydrogen tunnelling in the reaction.
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Affiliation(s)
| | - Cvijeta Jakobušić Brala
- Faculty of Pharmacy and Biochemistry, University of Zagreb, A. Kovačića 1, 10 000 Zagreb, Croatia; (A.K.M.); (V.P.)
| | | | - Stanko Uršić
- Faculty of Pharmacy and Biochemistry, University of Zagreb, A. Kovačića 1, 10 000 Zagreb, Croatia; (A.K.M.); (V.P.)
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34
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Pagano P, Guo Q, Ranasinghe C, Schroeder E, Robben K, Häse F, Ye H, Wickersham K, Aspuru-Guzik A, Major DT, Gakhar L, Kohen A, Cheatum CM. Oscillatory Active-site Motions Correlate with Kinetic Isotope Effects in Formate Dehydrogenase. ACS Catal 2019; 9:11199-11206. [PMID: 33996196 PMCID: PMC8118594 DOI: 10.1021/acscatal.9b03345] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Thermal motions of enzymes have been invoked to explain the temperature dependence of kinetic isotope effects (KIE) in enzyme-catalyzed hydride transfers. Formate dehydrogenase (FDH) from Candida boidinii exhibits a temperature independent KIE that becomes temperature dependent upon mutation of hydrophobic residues in the active site. Ternary complexes of FDH that mimic the transition state structure allow investigation of how these mutations influence active-site dynamics. A combination of X-ray crystallography, two-dimensional infrared (2D IR) spectroscopy, and molecular dynamic simulations characterize the structure and dynamics of the active site. FDH exhibits oscillatory frequency fluctuations on the picosecond timescale, and the amplitude of these fluctuations correlates with the temperature dependence of the KIE. Both the kinetic and dynamic phenomena can be reproduced computationally. These results provide experimental evidence for a connection between the temperature dependence of KIEs and motions of the active site in an enzyme-catalyzed reaction consistent with activated tunneling models of the hydride transfer reaction.
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Affiliation(s)
- Philip Pagano
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Qi Guo
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Chethya Ranasinghe
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Evan Schroeder
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Kevin Robben
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Florian Häse
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Hepeng Ye
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Kyle Wickersham
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Alán Aspuru-Guzik
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
- Senior Fellow, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario M5G 1Z8, Canada
| | - Dan T. Major
- Chemistry Department, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Lokesh Gakhar
- Protein Crystallography Facility and Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Amnon Kohen
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
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35
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Hu S, Offenbacher AR, Lu ED, Klinman JP. Comparative kinetic isotope effects on first- and second-order rate constants of soybean lipoxygenase variants uncover a substrate-binding network. J Biol Chem 2019; 294:18069-18076. [PMID: 31624150 PMCID: PMC6885649 DOI: 10.1074/jbc.ra119.010826] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 10/14/2019] [Indexed: 01/08/2023] Open
Abstract
Lipoxygenases are widespread enzymes found in virtually all eukaryotes, including fungi, and, more recently, in prokaryotes. These enzymes act on long-chain polyunsaturated fatty acid substrates (C18 to C20), raising questions regarding how the substrate threads its way from solvent to the active site. Herein, we report a comparison of the temperature dependence of isotope effects on first- and second-order rate constants among single-site variants of the prototypic plant enzyme soybean lipoxygenase-1 substituted at amino acid residues inferred to impact substrate binding. We created 10 protein variants including four amino acid positions, Val-750, Ile-552, Ile-839, and Trp-500, located within a previously proposed substrate portal. The conversion of these bulky hydrophobic side chains to smaller side chains is concluded to increase the mobility of flanking helices, giving rise to increased off rates for substrate dissociation from the enzyme. In this manner, we identified a specific "binding network" that can regulate movement of the substrate from the solvent to the active site. Taken together with our previous findings on C-H and O2 activation of soybean lipoxygenase-1, these results support the emergence of multiple complementary networks within a single protein scaffold that modulate different steps along the enzymatic reaction coordinate.
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Affiliation(s)
- Shenshen Hu
- Department of Chemistry, University of California, Berkeley, California 94720; California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720
| | - Adam R Offenbacher
- Department of Chemistry, University of California, Berkeley, California 94720; California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720; Department of Chemistry, East Carolina University, Greenville, North Carolina 27858
| | - Edbert D Lu
- Department of Chemistry, University of California, Berkeley, California 94720; California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720
| | - Judith P Klinman
- Department of Chemistry, University of California, Berkeley, California 94720; Department of Molecular and Cell Biology, University of California, Berkeley, California 94720; California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720.
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36
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Zaragoza JPT, Nguy A, Minnetian N, Deng Z, Iavarone AT, Offenbacher AR, Klinman JP. Detecting and Characterizing the Kinetic Activation of Thermal Networks in Proteins: Thermal Transfer from a Distal, Solvent-Exposed Loop to the Active Site in Soybean Lipoxygenase. J Phys Chem B 2019; 123:8662-8674. [PMID: 31580070 PMCID: PMC6944211 DOI: 10.1021/acs.jpcb.9b07228] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The rate-limiting chemical reaction catalyzed by soybean lipoxygenase (SLO) involves quantum mechanical tunneling of a hydrogen atom from substrate to its active site ferric-hydroxide cofactor. SLO has emerged as a prototypical system for linking the thermal activation of a protein scaffold to the efficiency of active site chemistry. Significantly, hydrogen-deuterium exchange-mass spectrometry (HDX-MS) experiments on wild type and mutant forms of SLO have uncovered trends in the enthalpic barriers for HDX within a solvent-exposed loop (positions 317-334) that correlate well with trends in the corresponding enthalpic barriers for kcat. A model for this behavior posits that collisions between water and loop 317-334 initiate thermal activation at the protein surface that is then propagated 15-34 Å inward toward the reactive carbon of substrate in proximity to the iron catalyst. In this study, we have prepared protein samples containing cysteine residues either at the tip of the loop 317-334 (Q322C) or on a control loop, 586-603 (S596C). Chemical modification of cysteines with the fluorophore 6-bromoacetyl-2-dimethylaminonaphthalene (Badan, BD) provides site-specific probes for the measurement of fluorescence relaxation lifetimes and Stokes shift decays as a function of temperature. Computational studies indicate that surface water structure is likely to be largely preserved in each sample. While both loops exhibit temperature-independent fluorescence relaxation lifetimes as do the Stokes shifts for S596C-BD, the activation enthalpy for the nanosecond solvent reorganization at Q322C-BD (Ea(ksolv) = 2.8(0.9) kcal/mol)) approximates the enthalpy of activation for catalytic C-H activation (Ea(kcat) = 2.3(0.4) kcal/mol). This study establishes and validates the methodology for measuring rates of rapid local motions at the protein/solvent interface of SLO. These new findings, when combined with previously published correlations between protein motions and the rate-limiting hydride transfer in a thermophilic alcohol dehydrogenase, provide experimental evidence for thermally induced "protein quakes" as the origin of enthalpic barriers in catalysis.
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Affiliation(s)
- Jan Paulo T. Zaragoza
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, California 94720, United States
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, United States
| | - Andy Nguy
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, United States
| | - Natalie Minnetian
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, United States
| | - Zhenyu Deng
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, United States
| | - Anthony T. Iavarone
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, California 94720, United States
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, United States
| | - Adam R. Offenbacher
- Department of Chemistry, East Carolina University, Greenville, North Carolina 27858
| | - Judith P. Klinman
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, California 94720, United States
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, United States
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California 94720, United States
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37
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Zhu W, Radadiya A, Bisson C, Wenzel S, Nordin BE, Martínez-Márquez F, Imasaki T, Sedelnikova SE, Coricello A, Baumann P, Berry AH, Nomanbhoy TK, Kozarich JW, Jin Y, Rice DW, Takagi Y, Richards NGJ. High-resolution crystal structure of human asparagine synthetase enables analysis of inhibitor binding and selectivity. Commun Biol 2019; 2:345. [PMID: 31552298 PMCID: PMC6748925 DOI: 10.1038/s42003-019-0587-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 08/21/2019] [Indexed: 12/20/2022] Open
Abstract
Expression of human asparagine synthetase (ASNS) promotes metastatic progression and tumor cell invasiveness in colorectal and breast cancer, presumably by altering cellular levels of L-asparagine. Human ASNS is therefore emerging as a bona fide drug target for cancer therapy. Here we show that a slow-onset, tight binding inhibitor, which exhibits nanomolar affinity for human ASNS in vitro, exhibits excellent selectivity at 10 μM concentration in HCT-116 cell lysates with almost no off-target binding. The high-resolution (1.85 Å) crystal structure of human ASNS has enabled us to identify a cluster of negatively charged side chains in the synthetase domain that plays a key role in inhibitor binding. Comparing this structure with those of evolutionarily related AMP-forming enzymes provides insights into intermolecular interactions that give rise to the observed binding selectivity. Our findings demonstrate the feasibility of developing second generation human ASNS inhibitors as lead compounds for the discovery of drugs against metastasis. Wen Zhu et al. report the crystal structure of human asparagine synthetase at a 1.85 Å resolution, enabling computational analysis of inhibitor binding. They also find new insights into the intermolecular interactions contributing to binding specificity of inhibitors.
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Affiliation(s)
- Wen Zhu
- 1School of Chemistry, Cardiff University, Cardiff, UK.,8Present Address: Department of Chemistry and California Institute for Quantitative Biosciences, University of California, Berkeley, CA USA
| | | | - Claudine Bisson
- 2Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK.,8Present Address: Department of Chemistry and California Institute for Quantitative Biosciences, University of California, Berkeley, CA USA
| | - Sabine Wenzel
- 3Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN USA
| | - Brian E Nordin
- 4ActivX Biosciences, Inc, La Jolla, CA USA.,Present Address: Vividion Therapeutics, San Diego, CA USA
| | - Francisco Martínez-Márquez
- 3Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN USA
| | - Tsuyoshi Imasaki
- 3Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN USA.,5Division of Structural Medicine and Anatomy, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Svetlana E Sedelnikova
- 2Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | | | | | - Alexandria H Berry
- 6Department of Biology, California Institute of Technology, Pasadena, CA USA
| | | | | | - Yi Jin
- 1School of Chemistry, Cardiff University, Cardiff, UK
| | - David W Rice
- 2Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - Yuichiro Takagi
- 3Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN USA
| | - Nigel G J Richards
- 1School of Chemistry, Cardiff University, Cardiff, UK.,7Foundation for Applied Molecular Evolution, Alachua, FL USA
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38
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The Structural Dynamics of Engineered β-Lactamases Vary Broadly on Three Timescales yet Sustain Native Function. Sci Rep 2019; 9:6656. [PMID: 31040324 PMCID: PMC6491436 DOI: 10.1038/s41598-019-42866-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 04/10/2019] [Indexed: 12/20/2022] Open
Abstract
Understanding the principles of protein dynamics will help guide engineering of protein function: altering protein motions may be a barrier to success or may be an enabling tool for protein engineering. The impact of dynamics on protein function is typically reported over a fraction of the full scope of motional timescales. If motional patterns vary significantly at different timescales, then only by monitoring motions broadly will we understand the impact of protein dynamics on engineering functional proteins. Using an integrative approach combining experimental and in silico methodologies, we elucidate protein dynamics over the entire span of fast to slow timescales (ps to ms) for a laboratory-engineered system composed of five interrelated β-lactamases: two natural homologs and three laboratory-recombined variants. Fast (ps-ns) and intermediate (ns-µs) dynamics were mostly conserved. However, slow motions (µs-ms) were few and conserved in the natural homologs yet were numerous and widely dispersed in their recombinants. Nonetheless, modified slow dynamics were functionally tolerated. Crystallographic B-factors from high-resolution X-ray structures were partly predictive of the conserved motions but not of the new slow motions captured in our solution studies. Our inspection of protein dynamics over a continuous range of timescales vividly illustrates the complexity of dynamic impacts of protein engineering as well as the functional tolerance of an engineered enzyme system to new slow motions.
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39
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On the use of noncompetitive kinetic isotope effects to investigate flavoenzyme mechanism. Methods Enzymol 2019; 620:115-143. [PMID: 31072484 DOI: 10.1016/bs.mie.2019.03.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This account describes the application of kinetic isotope effects (KIEs) to investigate the mechanistic properties of flavin dependent enzymes. Assays can be conducted during steady-state catalytic turnover of the flavoenzyme with its substrate or by using rapid-kinetic techniques to measure either the reductive or oxidative half-reactions of the enzyme. Great care should be taken to ensure that the observed effects are due to isotopic substitution and not other factors such as pH effects or changes in the solvent viscosity of the reaction mixture. Different types of KIEs are described along with a physical description of their origins and the unique information each can provide about the mechanism of an enzyme. Detailed experimental techniques are outlined with special emphasis on the proper controls and data analysis that must be carried out to avoid erroneous conclusions. Examples are provided for each type of KIE measurement from references in the literature. It is our hope that this article will clarify any confusion concerning the utility of KIEs in the study of flavoprotein mechanism and encourage their use by the community.
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40
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Johnson LE, Ginovska B, Fenton AW, Raugei S. Chokepoints in Mechanical Coupling Associated with Allosteric Proteins: The Pyruvate Kinase Example. Biophys J 2019; 116:1598-1608. [PMID: 31010662 DOI: 10.1016/j.bpj.2019.03.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/14/2019] [Accepted: 03/21/2019] [Indexed: 12/14/2022] Open
Abstract
Although the critical role of allostery in controlling enzymatic processes is well appreciated, there is a current dearth in our understanding of its underlying mechanisms, including communication between binding sites. One potential key aspect of intersite communication is the mechanical coupling between residues in a protein. Here, we introduce a graph-based computational approach to investigate the mechanical coupling between distant parts of a protein, highlighting effective pathways via which protein motion can transfer energy between sites. In this method, each residue is treated as a node on a weighted, undirected graph, in which the edges are defined by locally correlated motions of those residues and weighted by the strength of the correlation. The method was validated against experimental data on allosteric regulation in the human liver pyruvate kinase as obtained from full-protein alanine-scanning mutagenesis (systematic mutation) studies, as well as computational data on two G-protein-coupled receptors. The method provides semiquantitative information on the regulatory importance of specific structural elements. It is shown that these elements are key for the mechanical coupling between distant parts of the protein by providing effective pathways for energy transfer. It is also shown that, although there are a multitude of energy transfer pathways between distant parts of a protein, these pathways share a few common nodes that represent effective "chokepoints" for the communication.
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Affiliation(s)
- Lewis E Johnson
- Department of Chemistry, University of Washington, Seattle, Washington; Physical and Computational Sciences Directorate, Pacific Northwestern National Laboratory, Richland, Washington
| | - Bojana Ginovska
- Physical and Computational Sciences Directorate, Pacific Northwestern National Laboratory, Richland, Washington
| | - Aron W Fenton
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas
| | - Simone Raugei
- Physical and Computational Sciences Directorate, Pacific Northwestern National Laboratory, Richland, Washington.
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41
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Wongnate T, Surawatanawong P, Chuaboon L, Lawan N, Chaiyen P. The Mechanism of Sugar C−H Bond Oxidation by a Flavoprotein Oxidase Occurs by a Hydride Transfer Before Proton Abstraction. Chemistry 2019; 25:4460-4471. [DOI: 10.1002/chem.201806078] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 01/16/2019] [Indexed: 11/06/2022]
Affiliation(s)
- Thanyaporn Wongnate
- School of Biomolecular Science & EngineeringVidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley Rayong 21210 Thailand
| | - Panida Surawatanawong
- Department of Chemistry and Center of Excellence, for Innovation in ChemistryMahidol University Bangkok 10400 Thailand
| | - Litavadee Chuaboon
- Department of Biochemistry and Center for Excellence, in Protein and Enzyme Technology, Faculty of ScienceMahidol University Bangkok 10400 Thailand
| | - Narin Lawan
- Department of Chemistry, Faculty of ScienceChiang Mai University Chiang Mai 50200 Thailand
| | - Pimchai Chaiyen
- School of Biomolecular Science & EngineeringVidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley Rayong 21210 Thailand
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42
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Iorgu AI, Baxter NJ, Cliff MJ, Levy C, Waltho JP, Hay S, Scrutton NS. Nonequivalence of Second Sphere "Noncatalytic" Residues in Pentaerythritol Tetranitrate Reductase in Relation to Local Dynamics Linked to H-Transfer in Reactions with NADH and NADPH Coenzymes. ACS Catal 2018; 8:11589-11599. [PMID: 31119061 PMCID: PMC6516726 DOI: 10.1021/acscatal.8b02810] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 10/23/2018] [Indexed: 11/28/2022]
Abstract
![]()
Many enzymes that
catalyze hydride transfer reactions work via
a mechanism dominated by quantum mechanical tunneling. The involvement
of fast vibrational modes of the reactive complex is often inferred
in these reactions, as in the case of the NAD(P)H-dependent pentaerythritol
tetranitrate reductase (PETNR). Herein, we interrogated the H-transfer
mechanism in PETNR by designing conservative (L25I and I107L) and
side chain shortening (L25A and I107A) PETNR variants and using a
combination of experimental approaches (stopped-flow rapid kinetics,
X-ray crystallography, isotope/temperature dependence studies of H-transfer
and NMR spectroscopy). X-ray data show subtle changes in the local
environment of the targeted side chains but no major structural perturbation
caused by mutagenesis of these two second sphere active site residues.
However, temperature dependence studies of H-transfer revealed a coenzyme-specific
and complex thermodynamic equilibrium between different reactive configurations
in PETNR–coenzyme complexes. We find that mutagenesis of these
second sphere “noncatalytic” residues affects differently
the reactivity of PETNR with NADPH and NADH coenzymes. We attribute
this to subtle, dynamic structural changes in the PETNR active site,
the effects of which impact differently in the nonequivalent reactive
geometries of PETNR−NADH and PETNR−NADPH complexes.
This inference is confirmed through changes observed in the NMR chemical
shift data for PETNR complexes with unreactive 1,4,5,6-tetrahydro-NAD(P)
analogues. We show that H-transfer rates can (to some extent) be buffered
through entropy–enthalpy compensation, but that use of integrated
experimental tools reveals hidden complexities that implicate a role
for dynamics in this relatively simple H-transfer reaction. Similar
approaches are likely to be informative in other enzymes to understand
the relative importance of (distal) hydrophobic side chains and dynamics
in controlling the rates of enzymatic H-transfer.
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Affiliation(s)
- Andreea I. Iorgu
- Manchester Institute of Biotechnology and School of Chemistry, Faculty of Science and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Nicola J. Baxter
- Manchester Institute of Biotechnology and School of Chemistry, Faculty of Science and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, United Kingdom
| | - Matthew J. Cliff
- Manchester Institute of Biotechnology and School of Chemistry, Faculty of Science and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Colin Levy
- Manchester Institute of Biotechnology and School of Chemistry, Faculty of Science and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Jonathan P. Waltho
- Manchester Institute of Biotechnology and School of Chemistry, Faculty of Science and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, United Kingdom
| | - Sam Hay
- Manchester Institute of Biotechnology and School of Chemistry, Faculty of Science and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Nigel S. Scrutton
- Manchester Institute of Biotechnology and School of Chemistry, Faculty of Science and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
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43
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Roca M, Ruiz-Pernía JJ, Castillo R, Oliva M, Moliner V. Temperature dependence of dynamic, tunnelling and kinetic isotope effects in formate dehydrogenase. Phys Chem Chem Phys 2018; 20:25722-25737. [PMID: 30280169 DOI: 10.1039/c8cp04244f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The origin of the catalytic power of enzymes has been a question of debate for a long time. In this regard, the possible contribution of protein dynamics in enzymatic catalysis has become one of the most controversial topics. In the present work, the hydride transfer step in the formate dehydrogenase (FDH EC 1.2.1.2) enzyme is studied by means of molecular dynamic (MD) simulations with quantum mechanics/molecular mechanics (QM/MM) potentials in order to explore any correlation between dynamics, tunnelling effects and the rate constant. The temperature dependence of the kinetic isotope effects (KIEs), which is one of the few tests that can be studied by experiments and simulations to shed light on this debate, has been computed and the results have been compared with previous experimental data. The classical mechanical free energy barrier and the number of recrossing trajectories seem to be temperature-independent while the quantum vibrational corrections and the tunnelling effects are slightly temperature-dependent over the interval of 5-45 °C. The computed primary KIEs are in very good agreement with previous experimental data, being almost temperature-independent within the standard deviations. The modest dependence on the temperature is due to just the quantum vibrational correction contribution. These results, together with the analysis of the evolution of the collective variables such as the electrostatic potential or the electric field created by the protein on the key atoms involved in the reaction, confirm that while the protein is well preorganised, some changes take place along the reaction that favour the hydride transfer and the product release. Coordinates defining these movements are, in fact, part of the real reaction coordinate.
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Affiliation(s)
- Maite Roca
- Departament de Química Física i Analítica, Universitat Jaume I, 12071 Castellón, Spain.
| | | | - Raquel Castillo
- Departament de Química Física i Analítica, Universitat Jaume I, 12071 Castellón, Spain.
| | - Mónica Oliva
- Departament de Química Física i Analítica, Universitat Jaume I, 12071 Castellón, Spain.
| | - Vicent Moliner
- Departament de Química Física i Analítica, Universitat Jaume I, 12071 Castellón, Spain.
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44
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Pinney MM, Natarajan A, Yabukarski F, Sanchez DM, Liu F, Liang R, Doukov T, Schwans JP, Martinez TJ, Herschlag D. Structural Coupling Throughout the Active Site Hydrogen Bond Networks of Ketosteroid Isomerase and Photoactive Yellow Protein. J Am Chem Soc 2018; 140:9827-9843. [DOI: 10.1021/jacs.8b01596] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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45
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Boehr DD, D'Amico RN, O'Rourke KF. Engineered control of enzyme structural dynamics and function. Protein Sci 2018; 27:825-838. [PMID: 29380452 DOI: 10.1002/pro.3379] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 01/20/2018] [Accepted: 01/24/2018] [Indexed: 12/20/2022]
Abstract
Enzymes undergo a range of internal motions from local, active site fluctuations to large-scale, global conformational changes. These motions are often important for enzyme function, including in ligand binding and dissociation and even preparing the active site for chemical catalysis. Protein engineering efforts have been directed towards manipulating enzyme structural dynamics and conformational changes, including targeting specific amino acid interactions and creation of chimeric enzymes with new regulatory functions. Post-translational covalent modification can provide an additional level of enzyme control. These studies have not only provided insights into the functional role of protein motions, but they offer opportunities to create stimulus-responsive enzymes. These enzymes can be engineered to respond to a number of external stimuli, including light, pH, and the presence of novel allosteric modulators. Altogether, the ability to engineer and control enzyme structural dynamics can provide new tools for biotechnology and medicine.
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Affiliation(s)
- David D Boehr
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Rebecca N D'Amico
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Kathleen F O'Rourke
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
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46
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Carro J, Martínez-Júlvez M, Medina M, Martínez AT, Ferreira P. Protein dynamics promote hydride tunnelling in substrate oxidation by aryl-alcohol oxidase. Phys Chem Chem Phys 2018; 19:28666-28675. [PMID: 29043303 DOI: 10.1039/c7cp05904c] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The temperature dependence of hydride transfer from the substrate to the N5 of the FAD cofactor during the reductive half-reaction of Pleurotus eryngii aryl-alcohol oxidase (AAO) is assessed here. Kinetic isotope effects on both the pre-steady state reduction of the enzyme and its steady-state kinetics, with differently deuterated substrates, suggest an environmentally-coupled quantum-mechanical tunnelling process. Moreover, those kinetic data, along with the crystallographic structure of the enzyme in complex with a substrate analogue, indicate that AAO shows a pre-organized active site that would only require the approaching of the hydride donor and acceptor for the tunnelled transfer to take place. Modification of the enzyme's active-site architecture by replacement of Tyr92, a residue establishing hydrophobic interactions with the substrate analogue in the crystal structure, in the Y92F, Y92L and Y92W variants resulted in different temperature dependence patterns that indicated a role of this residue in modulating the transfer reaction.
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Affiliation(s)
- Juan Carro
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, E-28040, Madrid, Spain.
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47
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Shanmuganatham KK, Wallace RS, Ting-I Lee A, Plapp BV. Contribution of buried distal amino acid residues in horse liver alcohol dehydrogenase to structure and catalysis. Protein Sci 2018; 27:750-768. [PMID: 29271062 DOI: 10.1002/pro.3370] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 12/18/2017] [Accepted: 12/20/2017] [Indexed: 01/06/2023]
Abstract
The dynamics of enzyme catalysis range from the slow time scale (∼ms) for substrate binding and conformational changes to the fast time (∼ps) scale for reorganization of substrates in the chemical step. The contribution of global dynamics to catalysis by alcohol dehydrogenase was tested by substituting five different, conserved amino acid residues that are distal from the active site and located in the hinge region for the conformational change or in hydrophobic clusters. X-ray crystallography shows that the structures for the G173A, V197I, I220 (V, L, or F), V222I, and F322L enzymes complexed with NAD+ and an analogue of benzyl alcohol are almost identical, except for small perturbations at the sites of substitution. The enzymes have very similar kinetic constants for the oxidation of benzyl alcohol and reduction of benzaldehyde as compared to the wild-type enzyme, and the rates of conformational changes are not altered. Less conservative substitutions of these amino acid residues, such as G173(V, E, K, or R), V197(G, S, or T), I220(G, S, T, or N), and V222(G, S, or T) produced unstable or poorly expressed proteins, indicating that the residues are critical for global stability. The enzyme scaffold accommodates conservative substitutions of distal residues, and there is no evidence that fast, global dynamics significantly affect the rate constants for hydride transfers. In contrast, other studies show that proximal residues significantly participate in catalysis.
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Affiliation(s)
- Karthik K Shanmuganatham
- Department of Biochemistry, The University of Iowa, Iowa City, IA, 52242-1109.,Diagnostic Virology Laboratory, USDA, Ames, IA, 50010
| | - Rachel S Wallace
- Department of Biochemistry, The University of Iowa, Iowa City, IA, 52242-1109.,Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, 9054, New Zealand
| | - Ann Ting-I Lee
- Department of Biochemistry, The University of Iowa, Iowa City, IA, 52242-1109.,No 92, Jing Mao 1st Rd., Taichung, Taiwan, 406, Republic of China
| | - Bryce V Plapp
- Department of Biochemistry, The University of Iowa, Iowa City, IA, 52242-1109
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48
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Klinman JP, Offenbacher AR, Hu S. Origins of Enzyme Catalysis: Experimental Findings for C-H Activation, New Models, and Their Relevance to Prevailing Theoretical Constructs. J Am Chem Soc 2017; 139:18409-18427. [PMID: 29244501 PMCID: PMC5812730 DOI: 10.1021/jacs.7b08418] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The physical basis for enzymatic rate accelerations is a subject of great fundamental interest and of direct relevance to areas that include the de novo design of green catalysts and the pursuit of new drug regimens. Extensive investigations of C-H activating systems have provided considerable insight into the relationship between an enzyme's overall structure and the catalytic chemistry at its active site. This Perspective highlights recent experimental data for two members of distinct, yet iconic C-H activation enzyme classes, lipoxygenases and prokaryotic alcohol dehydrogenases. The data necessitate a reformulation of the dominant textbook definition of biological catalysis. A multidimensional model emerges that incorporates a range of protein motions that can be parsed into a combination of global stochastic conformational thermal fluctuations and local donor-acceptor distance sampling. These motions are needed to achieve a high degree of precision with regard to internuclear distances, geometries, and charges within the active site. The available model also suggests a physical framework for understanding the empirical enthalpic barrier in enzyme-catalyzed processes. We conclude by addressing the often conflicting interface between computational and experimental chemists, emphasizing the need for computation to predict experimental results in advance of their measurement.
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Affiliation(s)
- Judith P Klinman
- Department of Chemistry, University of California , Berkeley, California 94720, United States
- Department of Molecular and Cell Biology, University of California , Berkeley, California 94720, United States
- California Institute for Quantitative Biosciences, University of California , Berkeley, California 94720, United States
| | - Adam R Offenbacher
- Department of Chemistry, University of California , Berkeley, California 94720, United States
- California Institute for Quantitative Biosciences, University of California , Berkeley, California 94720, United States
| | - Shenshen Hu
- Department of Chemistry, University of California , Berkeley, California 94720, United States
- California Institute for Quantitative Biosciences, University of California , Berkeley, California 94720, United States
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49
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Ranasinghe C, Guo Q, Sapienza PJ, Lee AL, Quinn DM, Cheatum CM, Kohen A. Protein Mass Effects on Formate Dehydrogenase. J Am Chem Soc 2017; 139:17405-17413. [PMID: 29083897 PMCID: PMC5800309 DOI: 10.1021/jacs.7b08359] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Isotopically labeled enzymes (denoted as "heavy" or "Born-Oppenheimer" enzymes) have been used to test the role of protein dynamics in catalysis. The original idea was that the protein's higher mass would reduce the frequency of its normal-modes without altering its electrostatics. Heavy enzymes have been used to test if the vibrations in the native enzyme are coupled to the chemistry it catalyzes, and different studies have resulted in ambiguous findings. Here the temperature-dependence of intrinsic kinetic isotope effects of the enzyme formate dehydrogenase is used to examine the distribution of H-donor to H-acceptor distance as a function of the protein's mass. The protein dynamics are altered in the heavy enzyme to diminish motions that determine the transition state sampling in the native enzyme, in accordance with a Born-Oppenheimer-like effect on bond activation. Findings of this work suggest components related to fast frequencies that can be explained by Born-Oppenheimer enzyme hypothesis (vibrational) and also slower time scale events that are non-Born-Oppenheimer in nature (electrostatic), based on evaluations of protein mass dependence of donor-acceptor distance and forward commitment to catalysis along with steady state and single turnover measurements. Together, the findings suggest that the mass modulation affected both local, fast, protein vibrations associated with the catalyzed chemistry and the protein's macromolecular electrostatics at slower time scales; that is, both Born-Oppenheimer and non-Born-Oppenheimer effects are observed. Comparison to previous studies leads to the conclusion that isotopic labeling of the protein may have different effects on different systems, however, making heavy enzyme studies a very exciting technique for exploring the dynamics link to catalysis in proteins.
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Affiliation(s)
- Chethya Ranasinghe
- Department of Chemistry, University of Iowa, Iowa City, IA 52242-1727, USA
| | - Qi Guo
- Department of Chemistry, University of Iowa, Iowa City, IA 52242-1727, USA
| | - Paul J. Sapienza
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Andrew L. Lee
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Daniel M. Quinn
- Department of Chemistry, University of Iowa, Iowa City, IA 52242-1727, USA
| | | | - Amnon Kohen
- Department of Chemistry, University of Iowa, Iowa City, IA 52242-1727, USA
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Abstract
Enzyme isotope effects, or the kinetic effects of "heavy" enzymes, refer to the effect of isotopically labeled protein residues on the enzyme's activity or physical properties. These effects are increasingly employed in the examination of the possible contributions of protein dynamics to enzyme catalysis. One hypothesis assumed that isotopic substitution of all 12C, 14N, and nonexchangeable 1H by 13C, 15N, and 2H, would slow down protein picosecond to femtosecond dynamics without any effect on the system's electrostatics following the Born-Oppenheimer approximation. It was suggested that reduced reaction rates reported for several "heavy" enzymes accords with that hypothesis. However, numerous deviations from the predictions of that hypothesis were also reported. Current studies also attempt to test the role of individual residues by site-specific labeling or by labeling a pattern of residues on activity. It appears that in several systems the protein's fast dynamics are indeed reduced in "heavy" enzymes in a way that reduces the probability of barrier crossing of its chemical step. Other observations, however, indicated that slower protein dynamics are electrostatically altered in isotopically labeled enzymes. Interestingly, these effects appear to be system dependent, thus it might be premature to suggest a general role of "heavy" enzymes' effect on catalysis.
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