1
|
Kalmer TL, Ancajas CMF, Cohen CI, McDaniel JM, Oyedele AS, Thirman HL, Walker AS. Statistical Coupling Analysis Predicts Correlated Motions in Dihydrofolate Reductase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.18.599103. [PMID: 38948820 PMCID: PMC11213021 DOI: 10.1101/2024.06.18.599103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
The role of dynamics in enzymatic function is a highly debated topic. Dihydrofolate reductase (DHFR), due to its universality and the depth with which it has been studied, is a model system in this debate. Myriad previous works have identified networks of residues in positions near to and remote from the active site that are involved in dynamics and others that are important for catalysis. For example, specific mutations on the Met20 loop in E. coli DHFR (N23PP/S148A) are known to disrupt millisecond-timescale motions and reduce catalytic activity. However, how and if networks of dynamically coupled residues influence the evolution of DHFR is still an unanswered question. In this study, we first identify, by statistical coupling analysis and molecular dynamic simulations, a network of coevolving residues, which possess increased correlated motions. We then go on to show that allosteric communication in this network is selectively knocked down in N23PP/S148A mutant E. coli DHFR. Finally, we identify two sites in the human DHFR sector which may accommodate the Met20 loop double proline mutation while preserving dynamics. These findings strongly implicate protein dynamics as a driving force for evolution.
Collapse
Affiliation(s)
- Thomas L. Kalmer
- Department of Chemistry, Vanderbilt University Nashville, TN, USA
| | | | - Cameron I. Cohen
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Jade M. McDaniel
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | | | - Hannah L. Thirman
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Immunobiology, Vanderbilt University Medical Center, Nashville, TN, USA
- Chemical & Physical Biology Program, Vanderbilt University, Nashville, TN, USA
| | - Allison S. Walker
- Department of Chemistry, Vanderbilt University Nashville, TN, USA
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, TN, USA
| |
Collapse
|
2
|
Greisman JB, Dalton KM, Brookner DE, Klureza MA, Sheehan CJ, Kim IS, Henning RW, Russi S, Hekstra DR. Perturbative diffraction methods resolve a conformational switch that facilitates a two-step enzymatic mechanism. Proc Natl Acad Sci U S A 2024; 121:e2313192121. [PMID: 38386706 PMCID: PMC10907320 DOI: 10.1073/pnas.2313192121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 12/18/2023] [Indexed: 02/24/2024] Open
Abstract
Enzymes catalyze biochemical reactions through precise positioning of substrates, cofactors, and amino acids to modulate the transition-state free energy. However, the role of conformational dynamics remains poorly understood due to poor experimental access. This shortcoming is evident with Escherichia coli dihydrofolate reductase (DHFR), a model system for the role of protein dynamics in catalysis, for which it is unknown how the enzyme regulates the different active site environments required to facilitate proton and hydride transfer. Here, we describe ligand-, temperature-, and electric-field-based perturbations during X-ray diffraction experiments to map the conformational dynamics of the Michaelis complex of DHFR. We resolve coupled global and local motions and find that these motions are engaged by the protonated substrate to promote efficient catalysis. This result suggests a fundamental design principle for multistep enzymes in which pre-existing dynamics enable intermediates to drive rapid electrostatic reorganization to facilitate subsequent chemical steps.
Collapse
Affiliation(s)
- Jack B. Greisman
- Department of Molecular & Cellular Biology, Harvard University, Cambridge, MA02138
| | - Kevin M. Dalton
- Department of Molecular & Cellular Biology, Harvard University, Cambridge, MA02138
| | - Dennis E. Brookner
- Department of Molecular & Cellular Biology, Harvard University, Cambridge, MA02138
| | - Margaret A. Klureza
- Department of Chemistry & Chemical Biology, Harvard University, Cambridge, MA02138
| | - Candice J. Sheehan
- Department of Molecular & Cellular Biology, Harvard University, Cambridge, MA02138
| | - In-Sik Kim
- BioCARS, Argonne National Laboratory, The University of Chicago, Lemont, IL60439
| | - Robert W. Henning
- BioCARS, Argonne National Laboratory, The University of Chicago, Lemont, IL60439
| | - Silvia Russi
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA94025
| | - Doeke R. Hekstra
- Department of Molecular & Cellular Biology, Harvard University, Cambridge, MA02138
- School of Engineering & Applied Sciences, Harvard University, Allston, MA02134
| |
Collapse
|
3
|
Greisman JB, Dalton KM, Brookner DE, Klureza MA, Sheehan CJ, Kim IS, Henning RW, Russi S, Hekstra DR. Resolving conformational changes that mediate a two-step catalytic mechanism in a model enzyme. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.02.543507. [PMID: 37398233 PMCID: PMC10312612 DOI: 10.1101/2023.06.02.543507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Enzymes catalyze biochemical reactions through precise positioning of substrates, cofactors, and amino acids to modulate the transition-state free energy. However, the role of conformational dynamics remains poorly understood due to lack of experimental access. This shortcoming is evident with E. coli dihydrofolate reductase (DHFR), a model system for the role of protein dynamics in catalysis, for which it is unknown how the enzyme regulates the different active site environments required to facilitate proton and hydride transfer. Here, we present ligand-, temperature-, and electric-field-based perturbations during X-ray diffraction experiments that enable identification of coupled conformational changes in DHFR. We identify a global hinge motion and local networks of structural rearrangements that are engaged by substrate protonation to regulate solvent access and promote efficient catalysis. The resulting mechanism shows that DHFR's two-step catalytic mechanism is guided by a dynamic free energy landscape responsive to the state of the substrate.
Collapse
Affiliation(s)
- Jack B. Greisman
- Department of Molecular & Cellular Biology, Harvard University, Cambridge, MA, United States
| | - Kevin M. Dalton
- Department of Molecular & Cellular Biology, Harvard University, Cambridge, MA, United States
| | - Dennis E. Brookner
- Department of Molecular & Cellular Biology, Harvard University, Cambridge, MA, United States
| | - Margaret A. Klureza
- Department of Chemistry & Chemical Biology, Harvard University, Cambridge, MA, United States
| | - Candice J. Sheehan
- Department of Molecular & Cellular Biology, Harvard University, Cambridge, MA, United States
| | - In-Sik Kim
- BioCARS, The University of Chicago, Argonne National Laboratory, Lemont, IL, United States
| | - Robert W. Henning
- BioCARS, The University of Chicago, Argonne National Laboratory, Lemont, IL, United States
| | - Silvia Russi
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, United States
| | - Doeke R. Hekstra
- Department of Molecular & Cellular Biology, Harvard University, Cambridge, MA, United States
- School of Engineering & Applied Sciences, Harvard University, Allston, MA, United States
| |
Collapse
|
4
|
Li J, Lin J, Kohen A, Singh P, Francis K, Cheatum CM. Evolution of Optimized Hydride Transfer Reaction and Overall Enzyme Turnover in Human Dihydrofolate Reductase. Biochemistry 2021; 60:3822-3828. [PMID: 34875176 PMCID: PMC8697555 DOI: 10.1021/acs.biochem.1c00558] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Evolution of dihydrofolate
reductase (DHFR) has been studied using
the enzyme from Escherichia coli DHFR
(ecDHFR) as a model, but less studies have used the enzyme from Homo sapiens DHFR (hsDHFR). Each enzyme maintains
a short and narrow distribution of hydride donor-acceptor distances
(DAD) at the tunneling ready state (TRS). Evolution of the enzyme
was previously studied in ecDHFR where three key sites were identified
as important to the catalyzed reaction. The corresponding sites in
hsDHFR are F28, 62-PEKN, and 26-PPLR. Each of these sites was studied
here through the creation of mutant variants of the enzyme and measurements
of the temperature dependence of the intrinsic kinetic isotope effects
(KIEs) on the reaction. F28 is mutated first to M (F28M) and then
to the L of the bacterial enzyme (F28L). The KIEs of the F28M variant
are larger and more temperature-dependent than wild-type (WT), suggesting
a broader and longer average DAD at the TRS. To more fully mimic ecDHFR,
we also study a triple mutant of the human enzyme (F32L-PP26N-PEKN62G).
Remarkably, the intrinsic KIEs, while larger in magnitude, are temperature-independent
like the WT enzymes. We also construct deletion mutations of hsDHFR
removing both the 62-PEKN and 26-PPLR sequences. The results mirror
those described previously for insertion mutants of ecDHFR. Taken
together, these results suggest a balancing act during DHFR evolution
between achieving an optimal TRS for hydride transfer and preventing
product inhibition arising from the different intercellular pools
of NADPH and NADP+ in prokaryotic and eukaryotic cells.
Collapse
Affiliation(s)
- Jiayue Li
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Jennifer Lin
- 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
| | - Priyanka Singh
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Kevin Francis
- Texas A&M University-Kingsville, Kingsville, Texas 78363, United States
| | | |
Collapse
|
5
|
Singh A, Fenwick RB, Dyson HJ, Wright PE. Role of Active Site Loop Dynamics in Mediating Ligand Release from E. coli Dihydrofolate Reductase. Biochemistry 2021; 60:2663-2671. [PMID: 34428034 DOI: 10.1021/acs.biochem.1c00461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Conformational fluctuations from ground-state to sparsely populated but functionally important excited states play a key role in enzyme catalysis. For Escherichia coli dihydrofolate reductase (DHFR), the release of the product tetrahydrofolate (THF) and oxidized cofactor NADP+ occurs through exchange between closed and occluded conformations of the Met20 loop. A "dynamic knockout" mutant of E. coli DHFR, where the E. coli sequence in the Met20 loop is replaced by the human sequence (N23PP/S148A), models human DHFR and is incapable of accessing the occluded conformation. 1H and 15N CPMG relaxation dispersion analysis for the ternary product complex of the mutant enzyme with NADP+ and the product analogue 5,10-dideazatetrahydrofolate (ddTHF) (E:ddTHF:NADP+) reveals the mechanism by which NADP+ is released when the Met20 loop cannot undergo the closed-to-occluded conformational transition. Two excited states were observed: one related to a faster, relatively high-amplitude conformational fluctuation in areas near the active site, associated with the shuttling of the nicotinamide ring of the cofactor out of the active site, and the other to a slower process where ddTHF undergoes small-amplitude motions within the binding site that are consistent with disorder observed in a room-temperature X-ray crystal structure of the N23PP/S148A mutant protein. These motions likely arise due to steric conflict of the pterin ring of ddTHF with the ribose-nicotinamide moiety of NADP+ in the closed active site. These studies demonstrate that site-specific kinetic information from relaxation dispersion experiments can provide intimate details of the changes in catalytic mechanism that result from small changes in local amino acid sequence.
Collapse
Affiliation(s)
- Amrinder Singh
- Department of Integrative Structural and Computational Biology, Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - R Bryn Fenwick
- Department of Integrative Structural and Computational Biology, Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - H Jane Dyson
- Department of Integrative Structural and Computational Biology, Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Peter E Wright
- Department of Integrative Structural and Computational Biology, Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| |
Collapse
|
6
|
Mhashal AR, Major DT. Temperature-Dependent Kinetic Isotope Effects in R67 Dihydrofolate Reductase from Path-Integral Simulations. J Phys Chem B 2021; 125:1369-1377. [PMID: 33522797 PMCID: PMC7883348 DOI: 10.1021/acs.jpcb.0c10318] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/05/2021] [Indexed: 11/28/2022]
Abstract
Calculation of temperature-dependent kinetic isotope effects (KIE) in enzymes presents a significant theoretical challenge. Additionally, it is not trivial to identify enzymes with available experimental accurate intrinsic KIEs in a range of temperatures. In the current work, we present a theoretical study of KIEs in the primitive R67 dihydrofolate reductase (DHFR) enzyme and compare with experimental work. The advantage of R67 DHFR is its significantly lower kinetic complexity compared to more evolved DHFR isoforms. We employ mass-perturbation-based path-integral simulations in conjunction with umbrella sampling and a hybrid quantum mechanics-molecular mechanics Hamiltonian. We obtain temperature-dependent KIEs in good agreement with experiments and ascribe the temperature-dependent KIEs primarily to zero-point energy effects. The active site in the primitive enzyme is found to be poorly preorganized, which allows excessive water access to the active site and results in loosely bound reacting ligands.
Collapse
Affiliation(s)
- Anil R. Mhashal
- Department of Chemistry and Institute
for Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Dan Thomas Major
- Department of Chemistry and Institute
for Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
| |
Collapse
|
7
|
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
|
8
|
Hu S, Offenbacher AR, Thompson EM, Gee CL, Wilcoxen J, Carr CAM, Prigozhin DM, Yang V, Alber T, Britt RD, Fraser JS, Klinman J. Biophysical Characterization of a Disabled Double Mutant of Soybean Lipoxygenase: The "Undoing" of Precise Substrate Positioning Relative to Metal Cofactor and an Identified Dynamical Network. J Am Chem Soc 2019; 141:1555-1567. [PMID: 30645119 PMCID: PMC6353671 DOI: 10.1021/jacs.8b10992] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Soybean lipoxygenase (SLO) has served as a prototype for understanding the molecular origin of enzymatic rate accelerations. The double mutant (DM) L546A/L754A is considered a dramatic outlier, due to the unprecedented size and near temperature-independence of its primary kinetic isotope effect, low catalytic efficiency, and elevated enthalpy of activation. To uncover the physical basis of these features, we herein apply three structural probes: hydrogen-deuterium exchange mass spectrometry, room-temperature X-ray crystallography and EPR spectroscopy on four SLO variants (wild-type (WT) enzyme, DM, and the two parental single mutants, L546A and L754A). DM is found to incorporate features of each parent, with the perturbation at position 546 predominantly influencing thermally activated motions that connect the active site to a protein-solvent interface, while mutation at position 754 disrupts the ligand field and solvation near the cofactor iron. However, the expanded active site in DM leads to more active site water molecules and their associated hydrogen bond network, and the individual features from L546A and L754A alone cannot explain the aggregate kinetic properties for DM. Using recently published QM/MM-derived ground-state SLO-substrate complexes for WT and DM, together with the thorough structural analyses presented herein, we propose that the impairment of DM is the combined result of a repositioning of the reactive carbon of linoleic acid substrate with regard to both the iron cofactor and a catalytically linked dynamic region of protein.
Collapse
Affiliation(s)
- Shenshen Hu
- California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, United States
- 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
| | - Adam R. Offenbacher
- California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, United States
- 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
- Department of Chemistry, East Carolina University, Greenville, NC 27858
| | - Erin M. Thompson
- Department of Bioengineering and Therapeutic Science, University of California, San Francisco, San Francisco, California 94158, United States
| | - Christine L. Gee
- California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, United States
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, United States
| | - Jarett Wilcoxen
- Department of Chemistry, University of California, Davis, California 95695, United States
| | - Cody A. M. Carr
- California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, United States
- 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
| | - Daniil M. Prigozhin
- California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, United States
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, United States
| | - Vanessa Yang
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Tom Alber
- California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, United States
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, United States
| | - R. David Britt
- Department of Chemistry, University of California, Davis, California 95695, United States
| | - James S. Fraser
- Department of Bioengineering and Therapeutic Science, University of California, San Francisco, San Francisco, California 94158, United States
| | - Judith Klinman
- California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, United States
- 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
| |
Collapse
|
9
|
Folate biosynthesis pathway: mechanisms and insights into drug design for infectious diseases. Future Med Chem 2018; 10:935-959. [PMID: 29629843 DOI: 10.4155/fmc-2017-0168] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Folate pathway is a key target for the development of new drugs against infectious diseases since the discovery of sulfa drugs and trimethoprim. The knowledge about this pathway has increased in the last years and the catalytic mechanism and structures of all enzymes of the pathway are fairly understood. In addition, differences among enzymes from prokaryotes and eukaryotes could be used for the design of specific inhibitors. In this review, we show a panorama of progress that has been achieved within the folate pathway obtained in the last years. We explored the structure and mechanism of enzymes, several genetic features, strategies, and approaches used in the design of new inhibitors that have been used as targets in pathogen chemotherapy.
Collapse
|
10
|
Reyes AC, Amyes TL, Richard JP. Enzyme Architecture: Self-Assembly of Enzyme and Substrate Pieces of Glycerol-3-Phosphate Dehydrogenase into a Robust Catalyst of Hydride Transfer. J Am Chem Soc 2016; 138:15251-15259. [PMID: 27792325 PMCID: PMC5291162 DOI: 10.1021/jacs.6b09936] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The stabilization of the transition
state for hlGPDH-catalyzed reduction of DHAP due
to the action of the phosphodianion
of DHAP and the cationic side chain of R269 is between 12.4 and 17
kcal/mol. The R269A mutation of glycerol-3-phosphate dehydrogenase
(hlGPDH) results in a 9.1 kcal/mol destabilization
of the transition state for enzyme-catalyzed reduction of dihydroxyacetone
phosphate (DHAP) by NADH, and there is a 6.7 kcal/mol stabilization of this transition state by 1.0 M guanidine cation (Gua+) [J. Am. Chem. Soc.2015, 137, 5312–5315]. The R269A mutant shows no detectable
activity toward reduction of glycolaldehyde (GA), or activation of
this reaction by 30 mM HPO32–. We report
the unprecedented self-assembly of R269A hlGPDH,
dianions (X2– = FPO32–, HPO32–, or SO42–), Gua+ and GA into a functioning catalyst of the reduction
of GA, and fourth-order reaction rate constants kcat/KGAKXKGua. The linear logarithmic correlation
(slope = 1.0) between values of kcat/KGAKX for dianion
activation of wildtype hlGPDH-catalyzed reduction
of GA and kcat/KGAKXKGua shows that the electrostatic interaction between exogenous dianions
and the side chain of R269 is not significantly perturbed by cutting hlGPDH into R269A and Gua+ pieces. The advantage
for connection of hlGPDH (R269A mutant + Gua+) and substrate pieces (GA + HPi) pieces, (ΔGS‡)HPi+E+Gua = 5.6 kcal/mol, is nearly equal to the sum
of the advantage to connection of the substrate pieces, (ΔGS‡)GA+HPi = 3.3 kcal/mol, for wildtype hlGPDH-catalyzed reaction of GA + HPi, and for connection
of the enzyme pieces, (ΔGS‡)E+Gua = 2.4
kcal/mol, for Gua+ activation of the R269A hlGPDH-catalyzed reaction of DHAP.
Collapse
Affiliation(s)
- Archie C Reyes
- Department of Chemistry, University at Buffalo, SUNY , Buffalo, New York 14260-3000, United States
| | - Tina L Amyes
- Department of Chemistry, University at Buffalo, SUNY , Buffalo, New York 14260-3000, United States
| | - John P Richard
- Department of Chemistry, University at Buffalo, SUNY , Buffalo, New York 14260-3000, United States
| |
Collapse
|
11
|
Swiderek K, Kohen A, Moliner V. The influence of active site conformations on the hydride transfer step of the thymidylate synthase reaction mechanism. Phys Chem Chem Phys 2016; 17:30793-804. [PMID: 25868526 DOI: 10.1039/c5cp01239b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The hydride transfer from C6 of tetrahydrofolate to the reaction's exocyclic methylene-dUMP intermediate is the rate limiting step in thymidylate synthase (TSase) catalysis. This step has been studied by means of QM/MM molecular dynamics simulations to generate the corresponding free energy surfaces. The use of two different initial X-ray structures has allowed exploring different conformational spaces and the existence of chemical paths with not only different reactivities but also different reaction mechanisms. The results confirm that this chemical conversion takes place preferentially via a concerted mechanism where the hydride transfer is conjugated to thiol-elimination from the product. The findings also confirm the labile character of the substrate-enzyme covalent bond established between the C6 of the nucleotide substrate and a conserved cysteine residue. The calculations also reproduce and rationalize a normal H/T 2° kinetic isotope effect measured for that step. From a computational point of view, the results demonstrate that the use of an incomplete number of coordinates to describe the real reaction coordinate can render biased results.
Collapse
Affiliation(s)
- Katarzyna Swiderek
- Departament de Química Física i Analítica, Universitat Jaume I, 12071 Castelló, Spain. and Institute of Applied Radiation Chemistry, Lodz University of Technology, 90-924 Lodz, Poland
| | - Amnon Kohen
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Vicent Moliner
- Departament de Química Física i Analítica, Universitat Jaume I, 12071 Castelló, Spain.
| |
Collapse
|
12
|
Vardi-Kilshtain A, Nitoker N, Major DT. Nuclear quantum effects and kinetic isotope effects in enzyme reactions. Arch Biochem Biophys 2015; 582:18-27. [DOI: 10.1016/j.abb.2015.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 03/02/2015] [Accepted: 03/03/2015] [Indexed: 11/28/2022]
|
13
|
Oyen D, Fenwick RB, Stanfield RL, Dyson HJ, Wright PE. Cofactor-Mediated Conformational Dynamics Promote Product Release From Escherichia coli Dihydrofolate Reductase via an Allosteric Pathway. J Am Chem Soc 2015; 137:9459-68. [PMID: 26147643 PMCID: PMC4521799 DOI: 10.1021/jacs.5b05707] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Indexed: 11/29/2022]
Abstract
The enzyme dihydrofolate reductase (DHFR, E) from Escherichia coli is a paradigm for the role of protein dynamics in enzyme catalysis. Previous studies have shown that the enzyme progresses through the kinetic cycle by modulating the dynamic conformational landscape in the presence of substrate dihydrofolate (DHF), product tetrahydrofolate (THF), and cofactor (NADPH or NADP(+)). This study focuses on the quantitative description of the relationship between protein fluctuations and product release, the rate-limiting step of DHFR catalysis. NMR relaxation dispersion measurements of millisecond time scale motions for the E:THF:NADP(+) and E:THF:NADPH complexes of wild-type and the Leu28Phe (L28F) point mutant reveal conformational exchange between an occluded ground state and a low population of a closed state. The backbone structures of the occluded ground states of the wild-type and mutant proteins are very similar, but the rates of exchange with the closed excited states are very different. Integrated analysis of relaxation dispersion data and THF dissociation rates measured by stopped-flow spectroscopy shows that product release can occur by two pathways. The intrinsic pathway consists of spontaneous product dissociation and occurs for all THF-bound complexes of DHFR. The allosteric pathway features cofactor-assisted product release from the closed excited state and is utilized only in the E:THF:NADPH complexes. The L28F mutation alters the partitioning between the pathways and results in increased flux through the intrinsic pathway relative to the wild-type enzyme. This repartitioning could represent a general mechanism to explain changes in product release rates in other E. coli DHFR mutants.
Collapse
Affiliation(s)
- David Oyen
- Department of Integrative
Structural and Computational Biology and Skaggs Institute for Chemical
Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - R. Bryn Fenwick
- Department of Integrative
Structural and Computational Biology and Skaggs Institute for Chemical
Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Robyn L. Stanfield
- Department of Integrative
Structural and Computational Biology and Skaggs Institute for Chemical
Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - H. Jane Dyson
- Department of Integrative
Structural and Computational Biology and Skaggs Institute for Chemical
Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Peter E. Wright
- Department of Integrative
Structural and Computational Biology and Skaggs Institute for Chemical
Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| |
Collapse
|
14
|
Singh P, Francis K, Kohen A. Network of remote and local protein dynamics in dihydrofolate reductase catalysis. ACS Catal 2015; 5:3067-3073. [PMID: 27182453 DOI: 10.1021/acscatal.5b00331] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular dynamics calculations and bionformatic studies of dihydrofolate reductase (DHFR) have suggested a network of coupled motions across the whole protein that is correlated to the reaction coordinate. Experimental studies demonstrated that distal residues G121, M42 and F125 in E. coli DHFR participate in that network. The missing link in our understanding of DHFR catalysis is the lack of a mechanism by which such remote residues can affect the catalyzed chemistry at the active site. Here, we present a study of the temperature dependence of intrinsic kinetic isotope effects (KIEs) that indicates synergism between a remote residue in that dynamic network, G121, and the active site's residue I14. The intrinsic KIEs for the I14A-G121V double mutant showed steeper temperature dependence (ΔEa(T-H)) than expected from comparison of the wild type and two single mutants. That effect was non-additive, i.e., ΔEa(T-H)G121V +ΔEa(T-H) I14A < ΔEa(T-H) double mutant, which indicates a synergism between the two residues. This finding links the remote residues in the network under investigation to the enzyme's active site, providing a mechanism by which these residues can be coupled to the catalyzed chemistry. This experimental evidence validates calculations proposing that both remote and active site residues constitute a network of coupled promoting motions correlated to the bond activation step (C-H→C hydride transfer in this case). Additionally, the effect of I14A and G121V mutations on single turnover rates was additive rather than synergistic. Although single turnover rate measurements are more readily available and thus more popular than assessing intrinsic kinetic isotope effects, the current finding demonstrates that for these rates, which in DHFR reflect several microscopic rate constants, can fall short of revealing the nature of the C-H bond activation per se.
Collapse
Affiliation(s)
- Priyanka Singh
- The Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States
| | - Kevin Francis
- The Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States
| | - Amnon Kohen
- The Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States
| |
Collapse
|
15
|
Abstract
![]()
The active
site of an enzyme is surrounded by a fluctuating environment of protein
and solvent conformational states, and a realistic calculation of
chemical reaction rates and kinetic isotope effects of enzyme-catalyzed
reactions must take account of this environmental diversity. Ensemble-averaged
variational transition state theory with multidimensional tunneling
(EA-VTST/MT) was developed as a way to carry out such calculations.
This theory incorporates ensemble averaging, quantized vibrational
energies, energy, tunneling, and recrossing of transition state dividing
surfaces in a systematic way. It has been applied successfully to
a number of hydrogen-, proton-, and hydride-transfer reactions. The
theory also exposes the set of effects that should be considered in
reliable rate constants calculations. We first review the basic
theory and the steps in the calculation. A key role is played by the
generalized free energy of activation profile, which is obtained by
quantizing the classical potential of mean force as a function of
a reaction coordinate because the one-way flux through the transition
state dividing surface can be written in terms of the generalized
free energy of activation. A recrossing transmission coefficient accounts
for the difference between the one-way flux through the chosen transition
state dividing surface and the net flux, and a tunneling transmission
coefficient converts classical motion along the reaction coordinate
to quantum mechanical motion. The tunneling calculation is multidimensional,
accounting for the change in vibrational frequencies along the tunneling
path and shortening of the tunneling path with respect to the minimum
energy path (MEP), as promoted by reaction-path curvature. The generalized
free energy of activation and the transmission coefficients both involve
averaging over an ensemble of reaction paths and conformations, and
this includes the coupling of protein motions to the rearrangement
of chemical bonds in a statistical mechanically correct way. The standard
deviations of the transmissions coefficients provide information on
the diversity of the distribution of reaction paths, barriers, and
protein conformations along the members of an ensemble of reaction
paths passing through the transition state. We first illustrate
the theory by discussing the application to both wild-type and mutant Escherichia coli dihydrofolate reductase and hyperthermophilic Thermotoga maritima dihydrofolate reductase (DHFR); DHFR
is of special interest because the protein conformational changes
have been widely studied. Then we present shorter discussions of several
other applications of EA-VTST/MT to transfer of protons, hydrogen
atoms, and hydride ions and their deuterated analogs. Systems discussed
include hydride transfer in alcohol dehydrogenase, xylose isomerase,
and thymidylate synthase, proton transfer in methylamine dehydrogenase,
hydrogen atom transfer in methylmalonyl-CoA mutase, and nucleophilic
substitution in haloalkane dehalogenase and two-dimensional potentials
of mean force for potentially coupled proton and hydride transfer
in the β-oxidation of butyryl-coenzyme A catalyzed by short-chain
acyl-CoA dehydrogenase and in the pyruvate to lactate transformation
catalyzed by lactate dehydrogenase.
Collapse
Affiliation(s)
- Laura Masgrau
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
| | - Donald G. Truhlar
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455-0431, United States
| |
Collapse
|
16
|
Reyes A, Zhai X, Morgan KT, Reinhardt CJ, Amyes TL, Richard JP. The activating oxydianion binding domain for enzyme-catalyzed proton transfer, hydride transfer, and decarboxylation: specificity and enzyme architecture. J Am Chem Soc 2015; 137:1372-82. [PMID: 25555107 PMCID: PMC4311969 DOI: 10.1021/ja5123842] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Indexed: 11/29/2022]
Abstract
The kinetic parameters for activation of yeast triosephosphate isomerase (ScTIM), yeast orotidine monophosphate decarboxylase (ScOMPDC), and human liver glycerol 3-phosphate dehydrogenase (hlGPDH) for catalysis of reactions of their respective phosphodianion truncated substrates are reported for the following oxydianions: HPO3(2-), FPO3(2-), S2O3(2-), SO4(2-) and HOPO3(2-). Oxydianions bind weakly to these unliganded enzymes and tightly to the transition state complex (E·S(‡)), with intrinsic oxydianion Gibbs binding free energies that range from -8.4 kcal/mol for activation of hlGPDH-catalyzed reduction of glycolaldehyde by FPO3(2-) to -3.0 kcal/mol for activation of ScOMPDC-catalyzed decarboxylation of 1-β-d-erythrofuranosyl)orotic acid by HOPO3(2-). Small differences in the specificity of the different oxydianion binding domains are observed. We propose that the large -8.4 kcal/mol and small -3.8 kcal/mol intrinsic oxydianion binding energy for activation of hlGPDH by FPO3(2-) and S2O3(2-), respectively, compared with activation of ScTIM and ScOMPDC reflect stabilizing and destabilizing interactions between the oxydianion -F and -S with the cationic side chain of R269 for hlGPDH. These results are consistent with a cryptic function for the similarly structured oxydianion binding domains of ScTIM, ScOMPDC and hlGPDH. Each enzyme utilizes the interactions with tetrahedral inorganic oxydianions to drive a conformational change that locks the substrate in a caged Michaelis complex that provides optimal stabilization of the different enzymatic transition states. The observation of dianion activation by stabilization of active caged Michaelis complexes may be generalized to the many other enzymes that utilize substrate binding energy to drive changes in enzyme conformation, which induce tight substrate fits.
Collapse
Affiliation(s)
- Archie
C. Reyes
- Department
of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, United States
| | - Xiang Zhai
- Department
of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, United States
| | - Kelsey T. Morgan
- Department
of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, United States
| | - Christopher J. Reinhardt
- Department
of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, United States
| | - Tina L. Amyes
- Department
of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, United States
| | - John P. Richard
- Department
of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, United States
| |
Collapse
|
17
|
Świderek K, Tuñón I, Martí S, Moliner V. Protein Conformational Landscapes and Catalysis. Influence of Active Site Conformations in the Reaction Catalyzed by L-Lactate Dehydrogenase. ACS Catal 2015; 5:1172-1185. [PMID: 25705562 DOI: 10.1021/cs501704f] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
In the last decade L-Lactate Dehydrogenase (LDH) has become an extremely useful marker in both clinical diagnosis and in monitoring the course of many human diseases. It has been assumed from the 80s that the full catalytic process of LDH starts with the binding of the cofactor and the substrate followed by the enclosure of the active site by a mobile loop of the protein before the reaction to take place. In this paper we show that the chemical step of the LDH catalyzed reaction can proceed within the open loop conformation, and the different reactivity of the different protein conformations would be in agreement with the broad range of rate constants measured in single molecule spectrometry studies. Starting from a recently solved X-ray diffraction structure that presented an open loop conformation in two of the four chains of the tetramer, QM/MM free energy surfaces have been obtained at different levels of theory. Depending on the level of theory used to describe the electronic structure, the free energy barrier for the transformation of pyruvate into lactate with the open conformation of the protein varies between 12.9 and 16.3 kcal/mol, after quantizing the vibrations and adding the contributions of recrossing and tunneling effects. These values are very close to the experimentally deduced one (14.2 kcal·mol-1) and ~2 kcal·mol-1 smaller than the ones obtained with the closed loop conformer. Calculation of primary KIEs and IR spectra in both protein conformations are also consistent with our hypothesis and in agreement with experimental data. Our calculations suggest that the closure of the active site is mainly required for the inverse process; the oxidation of lactate to pyruvate. According to this hypothesis H4 type LDH enzyme molecules, where it has been propose that lactate is transformed into pyruvate, should have a better ability to close the mobile loop than the M4 type LDH molecules.
Collapse
Affiliation(s)
- Katarzyna Świderek
- Departament
de Química Física, Universitat de València, 46100 Burjassot, Spain
- Institute
of Applied Radiation Chemistry, Lodz University of Technology, 90-924 Lodz, Poland
| | - Iñaki Tuñón
- Departament
de Química Física, Universitat de València, 46100 Burjassot, Spain
| | - Sergio Martí
- Departament
de Química Física i Analítica, Universitat Jaume I, 12071 Castelló, Spain
| | - Vicent Moliner
- Departament
de Química Física i Analítica, Universitat Jaume I, 12071 Castelló, Spain
| |
Collapse
|
18
|
Carvalho ATP, Barrozo A, Doron D, Kilshtain AV, Major DT, Kamerlin SCL. Challenges in computational studies of enzyme structure, function and dynamics. J Mol Graph Model 2014; 54:62-79. [PMID: 25306098 DOI: 10.1016/j.jmgm.2014.09.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 09/13/2014] [Accepted: 09/16/2014] [Indexed: 01/23/2023]
Abstract
In this review we give an overview of the field of Computational enzymology. We start by describing the birth of the field, with emphasis on the work of the 2013 chemistry Nobel Laureates. We then present key features of the state-of-the-art in the field, showing what theory, accompanied by experiments, has taught us so far about enzymes. We also briefly describe computational methods, such as quantum mechanics-molecular mechanics approaches, reaction coordinate treatment, and free energy simulation approaches. We finalize by discussing open questions and challenges.
Collapse
Affiliation(s)
- Alexandra T P Carvalho
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, S-751 24 Uppsala, Sweden
| | - Alexandre Barrozo
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, S-751 24 Uppsala, Sweden
| | - Dvir Doron
- Department of Chemistry and the Lise Meitner-Minerva Center of Computational Quantum Chemistry Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Alexandra Vardi Kilshtain
- Department of Chemistry and the Lise Meitner-Minerva Center of Computational Quantum Chemistry Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Dan Thomas Major
- Department of Chemistry and the Lise Meitner-Minerva Center of Computational Quantum Chemistry Bar-Ilan University, Ramat-Gan 52900, Israel.
| | - Shina Caroline Lynn Kamerlin
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, S-751 24 Uppsala, Sweden.
| |
Collapse
|