1
|
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.
Collapse
Affiliation(s)
- Steven D Schwartz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Adesina AS, Luk LYP, Allemann RK. Cryo-kinetics Reveal Dynamic Effects on the Chemistry of Human Dihydrofolate Reductase. Chembiochem 2021; 22:2410-2414. [PMID: 33876533 PMCID: PMC8360168 DOI: 10.1002/cbic.202100017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 04/16/2021] [Indexed: 12/03/2022]
Abstract
Effects of isotopic substitution on the rate constants of human dihydrofolate reductase (HsDHFR), an important target for anti-cancer drugs, have not previously been characterized due to its complex fast kinetics. Here, we report the results of cryo-measurements of the kinetics of the HsDHFR catalyzed reaction and the effects of protein motion on catalysis. Isotopic enzyme labeling revealed an enzyme KIE (kHLE /kHHE ) close to unity above 0 °C; however, the enzyme KIE was increased to 1.72±0.15 at -20 °C, indicating that the coupling of protein motions to the chemical step is minimized under optimal conditions but enhanced at non-physiological temperatures. The presented cryogenic approach provides an opportunity to probe the kinetics of mammalian DHFRs, thereby laying the foundation for characterizing their transition state structure.
Collapse
Affiliation(s)
| | - Louis Y. P. Luk
- School of ChemistryCardiff UniversityPark PlaceCardiffCF10 3ATUK
| | | |
Collapse
|
4
|
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
| | | |
Collapse
|
5
|
Galdadas I, Qu S, Oliveira ASF, Olehnovics E, Mack AR, Mojica MF, Agarwal PK, Tooke CL, Gervasio FL, Spencer J, Bonomo RA, Mulholland AJ, Haider S. Allosteric communication in class A β-lactamases occurs via cooperative coupling of loop dynamics. eLife 2021; 10:e66567. [PMID: 33755013 PMCID: PMC8060031 DOI: 10.7554/elife.66567] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 03/19/2021] [Indexed: 12/16/2022] Open
Abstract
Understanding allostery in enzymes and tools to identify it offer promising alternative strategies to inhibitor development. Through a combination of equilibrium and nonequilibrium molecular dynamics simulations, we identify allosteric effects and communication pathways in two prototypical class A β-lactamases, TEM-1 and KPC-2, which are important determinants of antibiotic resistance. The nonequilibrium simulations reveal pathways of communication operating over distances of 30 Å or more. Propagation of the signal occurs through cooperative coupling of loop dynamics. Notably, 50% or more of clinically relevant amino acid substitutions map onto the identified signal transduction pathways. This suggests that clinically important variation may affect, or be driven by, differences in allosteric behavior, providing a mechanism by which amino acid substitutions may affect the relationship between spectrum of activity, catalytic turnover, and potential allosteric behavior in this clinically important enzyme family. Simulations of the type presented here will help in identifying and analyzing such differences.
Collapse
Affiliation(s)
- Ioannis Galdadas
- University College London, Department of ChemistryLondonUnited Kingdom
| | - Shen Qu
- University College London School of Pharmacy, Pharmaceutical and Biological ChemistryLondonUnited Kingdom
| | - Ana Sofia F Oliveira
- University of Bristol, Centre for Computational Chemistry, School of ChemistryBristolUnited Kingdom
| | - Edgar Olehnovics
- University College London School of Pharmacy, Pharmaceutical and Biological ChemistryLondonUnited Kingdom
| | - Andrew R Mack
- Veterans Affairs Northeast Ohio Healthcare System, Research ServiceClevelandUnited States
- Case Western Reserve University, Department of Molecular Biology and MicrobiologyClevelandUnited States
| | - Maria F Mojica
- Veterans Affairs Northeast Ohio Healthcare System, Research ServiceClevelandUnited States
- Case Western Reserve University, Department of Infectious Diseases, School of MedicineClevelandUnited States
| | - Pratul K Agarwal
- Department of Physiological Sciences and High-Performance Computing Center, Oklahoma State UniversityStillwaterUnited States
| | - Catherine L Tooke
- University of Bristol, School of Cellular and Molecular MedicineBristolUnited Kingdom
| | - Francesco Luigi Gervasio
- University College London, Department of ChemistryLondonUnited Kingdom
- University College London, Institute of Structural and Molecular BiologyLondonUnited Kingdom
- University of Geneva, Pharmaceutical SciencesGenevaSwitzerland
| | - James Spencer
- University of Bristol, School of Cellular and Molecular MedicineBristolUnited Kingdom
| | - Robert A Bonomo
- Veterans Affairs Northeast Ohio Healthcare System, Research ServiceClevelandUnited States
- Case Western Reserve University, Department of Molecular Biology and MicrobiologyClevelandUnited States
- Case Western Reserve University, Department of Infectious Diseases, School of MedicineClevelandUnited States
- Case Western Reserve University, Department of BiochemistryClevelandUnited States
- Case Western Reserve University, Department of PharmacologyClevelandUnited States
- Case Western Reserve University, Department of Proteomics and BioinformaticsClevelandUnited States
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES)ClevelandUnited States
| | - Adrian J Mulholland
- University of Bristol, Centre for Computational Chemistry, School of ChemistryBristolUnited Kingdom
| | - Shozeb Haider
- University College London School of Pharmacy, Pharmaceutical and Biological ChemistryLondonUnited Kingdom
| |
Collapse
|
6
|
Acceleration of catalysis in dihydrofolate reductase by transient, site-specific photothermal excitation. Proc Natl Acad Sci U S A 2021; 118:2014592118. [PMID: 33468677 DOI: 10.1073/pnas.2014592118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have studied the role of protein dynamics in chemical catalysis in the enzyme dihydrofolate reductase (DHFR), using a pump-probe method that employs pulsed-laser photothermal heating of a gold nanoparticle (AuNP) to directly excite a local region of the protein structure and transient absorbance to probe the effect on enzyme activity. Enzyme activity is accelerated by pulsed-laser excitation when the AuNP is attached close to a network of coupled motions in DHFR (on the FG loop, containing residues 116-132, or on a nearby alpha helix). No rate acceleration is observed when the AuNP is attached away from the network (distal mutant and His-tagged mutant) with pulsed excitation, or for any attachment site with continuous wave excitation. We interpret these results within an energy landscape model in which transient, site-specific addition of energy to the enzyme speeds up the search for reactive conformations by activating motions that facilitate this search.
Collapse
|
7
|
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.
Collapse
|
8
|
Li Y, Zhang Y, Cheng Y, Du T, Zhang J. Solvent inhibition profiles and inverse solvent isotope effects for enzymatic methyl transfer catalyzed by nicotinamide N‐methyltransferase. J PHYS ORG CHEM 2020. [DOI: 10.1002/poc.4093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Yuping Li
- School of Pharmaceutical Science and Technology Tianjin University Tianjin China
| | - Yali Zhang
- School of Pharmaceutical Science and Technology Tianjin University Tianjin China
| | - Yiting Cheng
- School of Pharmaceutical Science and Technology Tianjin University Tianjin China
| | - Tianshu Du
- School of Pharmaceutical Science and Technology Tianjin University Tianjin China
| | - Jianyu Zhang
- School of Pharmaceutical Science and Technology Tianjin University Tianjin China
| |
Collapse
|
9
|
Chen JZ, Fowler DM, Tokuriki N. Comprehensive exploration of the translocation, stability and substrate recognition requirements in VIM-2 lactamase. eLife 2020; 9:e56707. [PMID: 32510322 PMCID: PMC7308095 DOI: 10.7554/elife.56707] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 06/06/2020] [Indexed: 12/12/2022] Open
Abstract
Metallo-β-lactamases (MBLs) degrade a broad spectrum of β-lactam antibiotics, and are a major disseminating source for multidrug resistant bacteria. Despite many biochemical studies in diverse MBLs, molecular understanding of the roles of residues in the enzyme's stability and function, and especially substrate specificity, is lacking. Here, we employ deep mutational scanning (DMS) to generate comprehensive single amino acid variant data on a major clinical MBL, VIM-2, by measuring the effect of thousands of VIM-2 mutants on the degradation of three representative classes of β-lactams (ampicillin, cefotaxime, and meropenem) and at two different temperatures (25°C and 37°C). We revealed residues responsible for expression and translocation, and mutations that increase resistance and/or alter substrate specificity. The distribution of specificity-altering mutations unveiled distinct molecular recognition of the three substrates. Moreover, these function-altering mutations are frequently observed among naturally occurring variants, suggesting that the enzymes have continuously evolved to become more potent resistance genes.
Collapse
Affiliation(s)
- John Z Chen
- Michael Smith Laboratories, University of British ColumbiaVancouverCanada
| | - Douglas M Fowler
- Department of Genome Sciences, University of WashingtonSeattleUnited States
- Department of Bioengineering, University of WashingtonSeattleUnited States
| | - Nobuhiko Tokuriki
- Michael Smith Laboratories, University of British ColumbiaVancouverCanada
| |
Collapse
|
10
|
Lansakara TI, Morris HS, Singh P, Kohen A, Tivanski AV. Rigid Double-Stranded DNA Linkers for Single Molecule Enzyme-Drug Interaction Measurements Using Molecular Recognition Force Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:4174-4183. [PMID: 32233509 DOI: 10.1021/acs.langmuir.9b03495] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Single-molecule studies can reveal the distribution of states and interactions between ligand-enzyme complexes not accessible for most studies that measure a large ensemble average response of many molecules. Furthermore, in some biological applications, the information regarding the outliers, not the average of measured properties, can be more important. The high spatial and force resolution provided by atomic force microscopy (AFM) under physiological conditions has been utilized in this study to quantify the force-distance relations of enzyme-drug interactions. Different immobilization techniques of the protein to a surface and the drug to AFM tip were quantitatively compared to improve the accuracy and precision of the measurement. Protein that is directly bound to the surface, forming a monolayer, was compared to enzyme molecules bound to the surface with rigid double-stranded (ds) DNA spacers. These surfaces immobilization techniques were studied with the drug bound directly to the AFM tip and drug bound via flexible poly(ethylene glycol) and rigid dsDNA linkers. The activity of the enzyme was found to be not significantly altered by immobilization methods relative to its activity in solution. The findings indicate that the approach for studying drug-enzyme interaction based on rigid dsDNA linker on the surface and either flexible or rigid linker on the tip affords straightforward, highly specific, reproducible, and accurate force measurements with a potential for single-molecule level studies. The method could facilitate in-depth examination of a broad spectrum of biological targets and potential drugs.
Collapse
Affiliation(s)
| | - Holly S Morris
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Priyanka Singh
- 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
| | - Alexei V Tivanski
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| |
Collapse
|
11
|
A novel method to determine antibiotic sensitivity in Bdellovibrio bacteriovorus reveals a DHFR-dependent natural trimethoprim resistance. Sci Rep 2020; 10:5315. [PMID: 32210253 PMCID: PMC7093396 DOI: 10.1038/s41598-020-62014-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/04/2020] [Indexed: 11/13/2022] Open
Abstract
Bdellovibrio bacteriovorus is a small Gram-negative bacterium and an obligate predator of other Gram-negative bacteria. Prey resistance to B. bacteriovorus attack is rare and transient. This consideration together with its safety and low immunogenicity makes B. bacteriovorus a valid alternative to antibiotics, especially in the treatment of multidrug resistant pathogens. In this study we developed a novel technique to estimate B. bacteriovorus sensitivity against antibiotics in order to make feasible the development and testing of co-therapies with antibiotics that would increase its antimicrobial efficacy and at the same time reduce the development of drug resistance. Results from tests performed with this technique show that among all tested antibiotics, trimethoprim has the lowest antimicrobial effect on B. bacteriovorus. Additional experiments revealed that the mechanism of trimethoprim resistance in B. bacteriovorus depends on the low affinity of this compound for the B. bacteriovorus dihydrofolate reductase (Bd DHFR).
Collapse
|
12
|
Li J, Fortunato G, Lin J, Agarwal PK, Kohen A, Singh P, Cheatum CM. Evolution Conserves the Network of Coupled Residues in Dihydrofolate Reductase. Biochemistry 2019; 58:3861-3868. [PMID: 31423766 PMCID: PMC7296831 DOI: 10.1021/acs.biochem.9b00460] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Understanding protein motions and their role in enzymatic reactions is an important and timely topic in enzymology. Protein motions that are involved in the chemical step of catalysis are particularly intriguing but difficult to identify. A global network of coupled residues in Escherichia coli dihydrofolate reductase (E. coli DHFR), which assists in catalyzing the chemical step, has previously been demonstrated through quantum mechanical/molecular mechanical and molecular dynamics simulations as well as bioinformatic analyses. A few specific residues (M42, G121, F125, and I14) were shown to function synergistically with measurements of single-turnover rates and the temperature dependence of intrinsic kinetic isotope effects (KIEsint) of site-directed mutants. This study hypothesizes that the global network of residues involved in the chemical step is evolutionarily conserved and probes homologous residues of the potential global network in human DHFR through measurements of the temperature dependence of KIEsint and computer simulations based on the empirical valence bond method. We study mutants M53W and S145V. Both of these remote residues are homologous to network residues in E. coli DHFR. Non-additive isotope effects on activation energy are observed between M53 and S145, indicating their synergistic effect on the chemical step in human DHFR, which suggests that both of these residues are part of a network affecting the chemical step in enzyme catalysis. This finding supports the hypothesis that human and E. coli DHFR share similar networks, consistent with evolutionary preservation of such networks.
Collapse
Affiliation(s)
- Jiayue Li
- Department of Chemistry, University of Iowa, Iowa City, IA 52242
| | | | - Jennifer Lin
- Department of Chemistry, University of Iowa, Iowa City, IA 52242
| | - Pratul K. Agarwal
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996
| | - Amnon Kohen
- Department of Chemistry, University of Iowa, Iowa City, IA 52242
| | - Priyanka Singh
- Department of Chemistry, University of Iowa, Iowa City, IA 52242
| | | |
Collapse
|
13
|
Stadler AM, Schneidewind J, Zamponi M, Knieps-Grünhagen E, Gholami S, Schwaneberg U, Rivalta I, Garavelli M, Davari MD, Jaeger KE, Krauss U. Ternary Complex Formation and Photoactivation of a Photoenzyme Results in Altered Protein Dynamics. J Phys Chem B 2019; 123:7372-7384. [PMID: 31380636 DOI: 10.1021/acs.jpcb.9b06608] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The interplay between protein dynamics and catalysis remains a fundamental question in enzymology. We here investigate the ns-timescale dynamics of a light-dependent NADPH:protochlorophyllide oxidoreductase (LPOR), a photoenzyme crucial for chlorophyll synthesis. LPORs catalyze the light-triggered trans addition of a hydride and a proton across the C17═C18 double bond of the chlorophyll precursor protochlorophyllide (Pchlide). Because of the lack of an LPOR structure, the global structural and dynamic consequences of LPOR/Pchlide/NADPH ternary complex formation remain elusive. Moreover, photoactivation of LPORs by low-light preillumination is controversially discussed as unequivocal proof for this phenomenon is lacking. By employing quasielastic neutron spectroscopy (QENS), we show that the formation of the ternary holoprotein complex as well as photoactivation lead to progressive rigidification of the protein. These findings are supported by thermostability measurements, which reveal different melting behavior and thermostabilities for the apo- and holoprotein ternary complexes. Molecular dynamics simulations in good agreement with the experimental QENS results suggest that the increased flexibility observed for the apoprotein stems from structural fluctuations of the NADPH and Pchlide substrate binding sites of the enzyme. On the basis of our results, in conjunction with activity and stability measurements, we provide independent proof for LPOR photoactivation, defined as a process that modifies the protein structure and dynamics, resulting in an increased substrate turnover. Our findings advance the structural and dynamic understanding of LPORs and provide a first link between protein dynamics and catalysis for this enzyme class.
Collapse
Affiliation(s)
| | | | - Michaela Zamponi
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ) , Forschungszentrum Jülich GmbH , Lichtenbergstr. 1 , 85748 Garching , Germany
| | | | - Samira Gholami
- Dipartimento di Chimica Industriale , Università degli Studi di Bologna , Viale del Risorgimento 4 , I-40136 Bologna , Italy
| | - Ulrich Schwaneberg
- Institute of Biotechnology , RWTH Aachen University , Worringer Weg 3 , D-52074 Aachen , Germany.,DWI-Leibniz Institute for Interactive Materials , Forckenbeckstraße 50 , 52056 Aachen , Germany
| | - Ivan Rivalta
- Université de Lyon, École Normale Supérieure de Lyon, CNRS, Université Claude Bernard Lyon 1, Laboratoire de Chimie UMR 5182 , F-69342 Lyon , France
| | - Marco Garavelli
- Dipartimento di Chimica Industriale , Università degli Studi di Bologna , Viale del Risorgimento 4 , I-40136 Bologna , Italy.,École Normale Supérieure de Lyon, CNRS, Laboratoire de Chimie UMR 5182, Université de Lyon , 46 Allée d'Italie , F-69364 Lyon Cedex 07 , France
| | - Mehdi D Davari
- Institute of Biotechnology , RWTH Aachen University , Worringer Weg 3 , D-52074 Aachen , Germany
| | - Karl-Erich Jaeger
- IBG-1: Biotechnologie , Forschungszentrum Jülich GmbH , D-52425 Jülich , Germany
| | | |
Collapse
|
14
|
Abstract
Advances in computational and experimental methods in enzymology have aided comprehension of enzyme-catalyzed chemical reactions. The main difficulty in comparing computational findings to rate measurements is that the first examines a single energy barrier, while the second frequently reflects a combination of many microscopic barriers. We present here intrinsic kinetic isotope effects and their temperature dependence as a useful experimental probe of a single chemical step in a complex kinetic cascade. Computational predictions are tested by this method for two model enzymes: dihydrofolate reductase and thymidylate synthase. The description highlights the significance of collaboration between experimentalists and theoreticians to develop a better understanding of enzyme-catalyzed chemical conversions.
Collapse
Affiliation(s)
- P Singh
- University of Iowa, Iowa City, IA, United States
| | - Z Islam
- University of Iowa, Iowa City, IA, United States
| | - A Kohen
- University of Iowa, Iowa City, IA, United States.
| |
Collapse
|
15
|
Ludwiczak J, Maj P, Wilk P, Frączyk T, Ruman T, Kierdaszuk B, Jarmuła A, Rode W. Phosphorylation of thymidylate synthase affects slow-binding inhibition by 5-fluoro-dUMP and N(4)-hydroxy-dCMP. MOLECULAR BIOSYSTEMS 2016; 12:1333-41. [PMID: 26916840 DOI: 10.1039/c6mb00026f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Endogenous thymidylate synthases, isolated from tissues or cultured cells of the same specific origin, have been reported to show differing slow-binding inhibition patterns. These were reflected by biphasic or linear dependence of the inactivation rate on time and accompanied by differing inhibition parameters. Considering its importance for chemotherapeutic drug resistance, the possible effect of thymidylate synthase inhibition by post-translational modification was tested, e.g. phosphorylation, by comparing sensitivities to inhibition by two slow-binding inhibitors, 5-fluoro-dUMP and N(4)-hydroxy-dCMP, of two fractions of purified recombinant mouse enzyme preparations, phosphorylated and non-phosphorylated, separated by metal oxide/hydroxide affinity chromatography on Al(OH)3 beads. The modification, found to concern histidine residues and influence kinetic properties by lowering Vmax, altered both the pattern of dependence of the inactivation rate on time from linear to biphasic, as well as slow-binding inhibition parameters, with each inhibitor studied. Being present on only one subunit of at least a great majority of phosphorylated enzyme molecules, it probably introduced dimer asymmetry, causing the altered time dependence of the inactivation rate pattern (biphasic with the phosphorylated enzyme) and resulting in asymmetric binding of each inhibitor studied. The latter is reflected by the ternary complexes, stable under denaturing conditions, formed by only the non-phosphorylated subunit of the phosphorylated enzyme with each of the two inhibitors and N(5,10)-methylenetetrahydrofolate. Inhibition of the phosphorylated enzyme by N(4)-hydroxy-dCMP was found to be strongly dependent on [Mg(2+)], cations demonstrated previously to also influence the activity of endogenous mouse TS isolated from tumour cells.
Collapse
Affiliation(s)
- Jan Ludwiczak
- Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warszawa, Poland.
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Francis K, Sapienza PJ, Lee AL, Kohen A. The Effect of Protein Mass Modulation on Human Dihydrofolate Reductase. Biochemistry 2016; 55:1100-6. [PMID: 26813442 DOI: 10.1021/acs.biochem.5b00945] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dihydrofolate reductase (DHFR) from Escherichia coli has long served as a model enzyme with which to elucidate possible links between protein dynamics and the catalyzed reaction. Such physical properties of its human counterpart have not been rigorously studied so far, but recent computer-based simulations suggest that these two DHFRs differ significantly in how closely coupled the protein dynamics and the catalyzed C-H → C hydride transfer step are. To test this prediction, two contemporary probes for studying the effect of protein dynamics on catalysis were combined here: temperature dependence of intrinsic kinetic isotope effects (KIEs), which are sensitive to the physical nature of the chemical step, and protein mass modulation, which slows down fast dynamics (femto- to picosecond time scale) throughout the protein. The intrinsic H/T KIEs of human DHFR, like those of E. coli DHFR, are shown to be temperature-independent in the range from 5 to 45 °C, indicating fast sampling of donor and acceptor distances (DADs) at the reaction's transition state (or tunneling ready state, TRS). Mass modulation of these enzymes through isotopic labeling with (13)C, (15)N, and (2)H at nonexchangeable hydrogens yields an 11% heavier enzyme. The additional mass has no effect on the intrinsic KIEs of the human enzyme. This finding indicates that the mass modulation of the human DHFR affects neither DAD distribution nor the DAD's conformational sampling dynamics. Furthermore, reduction in the enzymatic turnover number and the dissociation rate constant for the product indicate that the isotopic substitution affects kinetic steps that are not the catalyzed C-H → C hydride transfer. The findings are discussed in terms of fast dynamics and their role in catalysis, the comparison of calculations and experiments, and the interpretation of isotopically modulated heavy enzymes in general.
Collapse
Affiliation(s)
- Kevin Francis
- The Department of Chemistry, The University of Iowa , Iowa City, Iowa 52242, United States
| | - Paul J Sapienza
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina , Chapel Hill, North Carolina 27599, United States
| | - Andrew L Lee
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina , Chapel Hill, North Carolina 27599, United States
| | - Amnon Kohen
- The Department of Chemistry, The University of Iowa , Iowa City, Iowa 52242, United States
| |
Collapse
|
17
|
Matsuoka R, Shimada A, Komuro Y, Sugita Y, Kohda D. Rational design of crystal contact-free space in protein crystals for analyzing spatial distribution of motions within protein molecules. Protein Sci 2016; 25:754-68. [PMID: 26694222 DOI: 10.1002/pro.2867] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Revised: 12/18/2015] [Accepted: 12/18/2015] [Indexed: 12/16/2022]
Abstract
Contacts with neighboring molecules in protein crystals inevitably restrict the internal motions of intrinsically flexible proteins. The resultant clear electron densities permit model building, as crystallographic snapshot structures. Although these still images are informative, they could provide biased pictures of the protein motions. If the mobile parts are located at a site lacking direct contacts in rationally designed crystals, then the amplitude of the movements can be experimentally analyzed. We propose a fusion protein method, to create crystal contact-free space (CCFS) in protein crystals and to place the mobile parts in the CCFS. Conventional model building fails when large amplitude motions exist. In this study, the mobile parts appear as smeared electron densities in the CCFS, by suitable processing of the X-ray diffraction data. We applied the CCFS method to a highly mobile presequence peptide bound to the mitochondrial import receptor, Tom20, and a catalytically relevant flexible segment in the oligosaccharyltransferase, AglB. These two examples demonstrated the general applicability of the CCFS method to the analysis of the spatial distribution of motions within protein molecules.
Collapse
Affiliation(s)
- Rei Matsuoka
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Higashi-Ku, Fukuoka, 812-8582, Japan
| | - Atsushi Shimada
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Higashi-Ku, Fukuoka, 812-8582, Japan.,RIKEN Structural Biology Laboratory, Tsurumi, Yokohama, 230-0045, Japan
| | - Yasuaki Komuro
- RIKEN Theoretical Molecular Science Laboratory and iTHES, Wako, Saitama, 351-0198, Japan.,Department of physics, Graduate School of Science and Engineering, Chuo University, Bunkyo-Ku, Tokyo, 112-8551, Japan
| | - Yuji Sugita
- RIKEN Theoretical Molecular Science Laboratory and iTHES, Wako, Saitama, 351-0198, Japan
| | - Daisuke Kohda
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Higashi-Ku, Fukuoka, 812-8582, Japan.,Research Center for Live-Protein Dynamics, Kyushu University, Higashi-Ku, Fukuoka, 812-8582, Japan
| |
Collapse
|
18
|
Duff MR, Chopra S, Strader MB, Agarwal PK, Howell EE. Tales of Dihydrofolate Binding to R67 Dihydrofolate Reductase. Biochemistry 2015; 55:133-45. [PMID: 26637016 PMCID: PMC5147970 DOI: 10.1021/acs.biochem.5b00981] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Homotetrameric R67 dihydrofolate reductase possesses 222 symmetry and a single active site pore. This situation results in a promiscuous binding site that accommodates either the substrate, dihydrofolate (DHF), or the cofactor, NADPH. NADPH interacts more directly with the protein as it is larger than the substrate. In contrast, the p-aminobenzoyl-glutamate tail of DHF, as monitored by nuclear magnetic resonance and crystallography, is disordered when bound. To explore whether smaller active site volumes (which should decrease the level of tail disorder by confinement effects) alter steady state rates, asymmetric mutations that decreased the half-pore volume by ∼35% were constructed. Only minor effects on k(cat) were observed. To continue exploring the role of tail disorder in catalysis, 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide-mediated cross-linking between R67 DHFR and folate was performed. A two-folate, one-tetramer complex results in the loss of enzyme activity where two symmetry-related K32 residues in the protein are cross-linked to the carboxylates of two bound folates. The tethered folate could be reduced, although with a ≤30-fold decreased rate, suggesting decreased dynamics and/or suboptimal positioning of the cross-linked folate for catalysis. Computer simulations that restrain the dihydrofolate tail near K32 indicate that cross-linking still allows movement of the p-aminobenzoyl ring, which allows the reaction to occur. Finally, a bis-ethylene-diamine-α,γ-amide folate adduct was synthesized; both negatively charged carboxylates in the glutamate tail were replaced with positively charged amines. The K(i) for this adduct was ∼9-fold higher than for folate. These various results indicate a balance between folate tail disorder, which helps the enzyme bind substrate while dynamics facilitates catalysis.
Collapse
Affiliation(s)
- Michael R Duff
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996-0840, United States
| | - Shaileja Chopra
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996-0840, United States
| | - Michael Brad Strader
- Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration , Silver Spring, Maryland 20993, United States
| | - Pratul K Agarwal
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996-0840, United States.,Computer Science and Mathematics Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Elizabeth E Howell
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996-0840, United States
| |
Collapse
|
19
|
Abstract
An assay was developed for measuring the active-site concentration, activity, and thereby the catalytic turnover rate (kcat) of an immobilized dihydrofolate reductase model system (Singh et al., (2015), Anal. Biochem). This data article contains a calibration plot for the developed assay. In the calibration plot rate is plotted as a function of DHFR concentration and shows linear relationship. The concentration of immobilized enzyme was varied by using 5 different size mica chips. The dsDNA concentration was the same for all chips, assuming that the surface area of the mica chip dictates the resulting amount of bound enzyme (i.e. larger sized chip would have more bound DHFR). The activity and concentration of each chip was measured.
Collapse
|