1
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Fischer P, Schiewer E, Broser M, Busse W, Spreen A, Grosse M, Hegemann P, Bartl F. The Functionality of the DC Pair in a Rhodopsin Guanylyl Cyclase from Catenaria anguillulae. J Mol Biol 2024; 436:168375. [PMID: 38092286 DOI: 10.1016/j.jmb.2023.168375] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 11/26/2023] [Accepted: 11/27/2023] [Indexed: 12/29/2023]
Abstract
Rhodopsin guanylyl cyclases (RGCs) belong to the class of enzymerhodopsins catalyzing the transition from GTP into the second messenger cGMP, whereas light-regulation of enzyme activity is mediated by a membrane-bound microbial rhodopsin domain, that holds the catalytic center inactive in the dark. Structural determinants for activation of the rhodopsin moiety eventually leading to catalytic activity are largely unknown. Here, we investigate the mechanistic role of the D283-C259 (DC) pair that is hydrogen bonded via a water molecule as a crucial functional motif in the homodimeric C. anguillulae RGC. Based on a structural model of the DC pair in the retinal binding pocket obtained by MD simulation, we analyzed formation and kinetics of early and late photocycle intermediates of the rhodopsin domain wild type and specific DC pair mutants by combined UV-Vis and FTIR spectroscopy at ambient and cryo-temperatures. By assigning specific infrared bands to S-H vibrations of C259 we are able to show that the DC pair residues are tightly coupled. We show that deprotonation of D283 occurs already in the inactive L state as a prerequisite for M state formation, whereas structural changes of C259 occur in the active M state and early cryo-trapped intermediates. We propose a comprehensive molecular model for formation of the M state that activates the catalytic moiety. It involves light induced changes in bond strength and hydrogen bonding of the DC pair residues from the early J state to the active M state and explains the retarding effect of C259 mutants.
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Affiliation(s)
- Paul Fischer
- Institut für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstr, 42, 10115 Berlin, Germany.
| | - Enrico Schiewer
- Institut für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstr, 42, 10115 Berlin, Germany.
| | - Matthias Broser
- Institut für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstr, 42, 10115 Berlin, Germany.
| | - Wayne Busse
- Institut für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstr, 42, 10115 Berlin, Germany.
| | - Anika Spreen
- Institut für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstr, 42, 10115 Berlin, Germany.
| | - Max Grosse
- Institut für Biologie, Biophysikalische Chemie, Humboldt Universität zu Berlin, Invalidenstr, 42, 10115 Berlin, Germany.
| | - Peter Hegemann
- Institut für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstr, 42, 10115 Berlin, Germany.
| | - Franz Bartl
- Institut für Biologie, Biophysikalische Chemie, Humboldt Universität zu Berlin, Invalidenstr, 42, 10115 Berlin, Germany.
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2
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Wilson C, Karttunen M, de Groot BL, Gapsys V. Accurately Predicting Protein p Ka Values Using Nonequilibrium Alchemy. J Chem Theory Comput 2023; 19:7833-7845. [PMID: 37820376 PMCID: PMC10653114 DOI: 10.1021/acs.jctc.3c00721] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Indexed: 10/13/2023]
Abstract
The stability, solubility, and function of a protein depend on both its net charge and the protonation states of its individual residues. pKa is a measure of the tendency for a given residue to (de)protonate at a specific pH. Although pKa values can be resolved experimentally, theory and computation provide a compelling alternative. To this end, we assess the applicability of a nonequilibrium (NEQ) alchemical free energy method to the problem of pKa prediction. On a data set of 144 residues that span 13 proteins, we report an average unsigned error of 0.77 ± 0.09, 0.69 ± 0.09, and 0.52 ± 0.04 pK for aspartate, glutamate, and lysine, respectively. This is comparable to current state-of-the-art predictors and the accuracy recently reached using free energy perturbation methods (e.g., FEP+). Moreover, we demonstrate that our open-source, pmx-based approach can accurately resolve the pKa values of coupled residues and observe a substantial performance disparity associated with the lysine partial charges in Amber14SB/Amber99SB*-ILDN, for which an underused fix already exists.
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Affiliation(s)
- Carter
J. Wilson
- Department
of Mathematics, The University of Western
Ontario, N6A 5B7 London, Canada
- Centre
for Advanced Materials and Biomaterials Research (CAMBR), The University of Western Ontario, N6A 5B7 London, Canada
| | - Mikko Karttunen
- Centre
for Advanced Materials and Biomaterials Research (CAMBR), The University of Western Ontario, N6A 5B7 London, Canada
- Department
of Physics & Astronomy, The University
of Western Ontario, N6A
5B7 London, Canada
- Department
of Chemistry, The University of Western
Ontario, N6A 5B7 London, Canada
| | - Bert L. de Groot
- Computational
Biomolecular Dynamics Group, Department of Theoretical and Computational
Biophysics, Max Planck Institute for Multidisciplinary
Sciences, 37077 Göttingen, Germany
| | - Vytautas Gapsys
- Computational
Biomolecular Dynamics Group, Department of Theoretical and Computational
Biophysics, Max Planck Institute for Multidisciplinary
Sciences, 37077 Göttingen, Germany
- Computational
Chemistry, Janssen Research & Development, Janssen Pharmaceutica N. V., Turnhoutseweg 30, B-2340 Beerse, Belgium
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3
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Dragelj J, Karafoulidi-Retsou C, Katz S, Lenz O, Zebger I, Caserta G, Sacquin-Mora S, Mroginski MA. Conformational and mechanical stability of the isolated large subunit of membrane-bound [NiFe]-hydrogenase from Cupriavidus necator. Front Microbiol 2023; 13:1073315. [PMID: 36733774 PMCID: PMC9886862 DOI: 10.3389/fmicb.2022.1073315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 12/23/2022] [Indexed: 01/18/2023] Open
Abstract
Comprising at least a bipartite architecture, the large subunit of [NiFe]-hydrogenase harbors the catalytic nickel-iron site while the small subunit houses an array of electron-transferring Fe-S clusters. Recently, some [NiFe]-hydrogenase large subunits have been isolated showing an intact and redox active catalytic cofactor. In this computational study we have investigated one of these metalloproteins, namely the large subunit HoxG of the membrane-bound hydrogenase from Cupriavidus necator (CnMBH), targeting its conformational and mechanical stability using molecular modelling and long all-atom Gaussian accelerated molecular dynamics (GaMD). Our simulations predict that isolated HoxG is stable in aqueous solution and preserves a large portion of its mechanical properties, but loses rigidity in regions around the active site, in contrast to the MBH heterodimer. Inspired by biochemical data showing dimerization of the HoxG protein and IR measurements revealing an increased stability of the [NiFe] cofactor in protein preparations with higher dimer content, corresponding simulations of homodimeric forms were also undertaken. While the monomeric subunit contains several flexible regions, our data predicts a regained rigidity in homodimer models. Furthermore, we computed the electrostatic properties of models obtained by enhanced sampling with GaMD, which displays a significant amount of positive charge at the protein surface, especially in solvent-exposed former dimer interfaces. These data offer novel insights on the way the [NiFe] core is protected from de-assembly and provide hints for enzyme anchoring to surfaces, which is essential information for further investigations on these minimal enzymes.
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Affiliation(s)
- Jovan Dragelj
- Institut für Chemie, Technische Universität Berlin, Berlin, Germany
| | | | - Sagie Katz
- Institut für Chemie, Technische Universität Berlin, Berlin, Germany
| | - Oliver Lenz
- Institut für Chemie, Technische Universität Berlin, Berlin, Germany
| | - Ingo Zebger
- Institut für Chemie, Technische Universität Berlin, Berlin, Germany
| | - Giorgio Caserta
- Institut für Chemie, Technische Universität Berlin, Berlin, Germany
| | - Sophie Sacquin-Mora
- Institut für Chemie, Technische Universität Berlin, Berlin, Germany
- CNRS, UPR, Laboratoire de Biochimie Théorique, Université de Paris Cité, Paris, France
- Institut de Biologie Physico-Chimique-Fondation Edmond de Rotschild, PSL Research University, Paris, France
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4
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Fernandez Lahore RG, Pampaloni NP, Schiewer E, Heim MM, Tillert L, Vierock J, Oppermann J, Walther J, Schmitz D, Owald D, Plested AJR, Rost BR, Hegemann P. Calcium-permeable channelrhodopsins for the photocontrol of calcium signalling. Nat Commun 2022; 13:7844. [PMID: 36543773 PMCID: PMC9772239 DOI: 10.1038/s41467-022-35373-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 11/29/2022] [Indexed: 12/24/2022] Open
Abstract
Channelrhodopsins are light-gated ion channels used to control excitability of designated cells in large networks with high spatiotemporal resolution. While ChRs selective for H+, Na+, K+ and anions have been discovered or engineered, Ca2+-selective ChRs have not been reported to date. Here, we analyse ChRs and mutant derivatives with regard to their Ca2+ permeability and improve their Ca2+ affinity by targeted mutagenesis at the central selectivity filter. The engineered channels, termed CapChR1 and CapChR2 for calcium-permeable channelrhodopsins, exhibit reduced sodium and proton conductance in connection with strongly improved Ca2+ permeation at negative voltage and low extracellular Ca2+ concentrations. In cultured cells and neurons, CapChR2 reliably increases intracellular Ca2+ concentrations. Moreover, CapChR2 can robustly trigger Ca2+ signalling in hippocampal neurons. When expressed together with genetically encoded Ca2+ indicators in Drosophila melanogaster mushroom body output neurons, CapChRs mediate light-evoked Ca2+ entry in brain explants.
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Affiliation(s)
| | - Niccolò P Pampaloni
- Molecular Neuroscience and Biophysics, Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
- Institute of Biology, Cellular Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Enrico Schiewer
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - M-Marcel Heim
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Linda Tillert
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
- Neuroscience Research Center, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Johannes Vierock
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
- Neuroscience Research Center, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Johannes Oppermann
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Jakob Walther
- Department of Neurology with Experimental Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Dietmar Schmitz
- Neuroscience Research Center, Charité - Universitätsmedizin Berlin, Berlin, Germany
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - David Owald
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Andrew J R Plested
- Molecular Neuroscience and Biophysics, Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
- Institute of Biology, Cellular Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Benjamin R Rost
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Peter Hegemann
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
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5
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Vierock J, Peter E, Grimm C, Rozenberg A, Chen IW, Tillert L, Castro Scalise AG, Casini M, Augustin S, Tanese D, Forget BC, Peyronnet R, Schneider-Warme F, Emiliani V, Béjà O, Hegemann P. WiChR, a highly potassium-selective channelrhodopsin for low-light one- and two-photon inhibition of excitable cells. SCIENCE ADVANCES 2022; 8:eadd7729. [PMID: 36383037 PMCID: PMC9733931 DOI: 10.1126/sciadv.add7729] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Accepted: 10/28/2022] [Indexed: 05/30/2023]
Abstract
The electric excitability of muscle, heart, and brain tissue relies on the precise interplay of Na+- and K+-selective ion channels. The involved ion fluxes are controlled in optogenetic studies using light-gated channelrhodopsins (ChRs). While non-selective cation-conducting ChRs are well established for excitation, K+-selective ChRs (KCRs) for efficient inhibition have only recently come into reach. Here, we report the molecular analysis of recently discovered KCRs from the stramenopile Hyphochytrium catenoides and identification of a novel type of hydrophobic K+ selectivity filter. Next, we demonstrate that the KCR signature motif is conserved in related stramenopile ChRs. Among them, WiChR from Wobblia lunata features a so far unmatched preference for K+ over Na+, stable photocurrents under continuous illumination, and a prolonged open-state lifetime. Showing high expression levels in cardiac myocytes and neurons, WiChR allows single- and two-photon inhibition at low irradiance and reduced tissue heating. Therefore, we recommend WiChR as the long-awaited efficient and versatile optogenetic inhibitor.
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Affiliation(s)
- Johannes Vierock
- Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu Berlin, Berlin, Germany
- Neuroscience Research Center, Charité–Universitätsmedizin Berlin, Berlin, Germany
| | - Enrico Peter
- Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Christiane Grimm
- Wavefront Engineering Microscopy Group, Photonics Department, Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Andrey Rozenberg
- Faculty of Biology, Technion–Israel Institute of Technology, Haifa 32000, Israel
| | - I-Wen Chen
- Wavefront Engineering Microscopy Group, Photonics Department, Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Linda Tillert
- Neuroscience Research Center, Charité–Universitätsmedizin Berlin, Berlin, Germany
| | | | - Marilù Casini
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg · Bad Krozingen, Medical Center and Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
- Regenerative Medicine and Heart Transplantation Unit, Instituto de Investigación Sanitaria La Fe and ITACA Institute (COR), Universitat Politècnica de València, Valencia, Spain
| | - Sandra Augustin
- Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Dimitrii Tanese
- Wavefront Engineering Microscopy Group, Photonics Department, Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Benoît C. Forget
- Wavefront Engineering Microscopy Group, Photonics Department, Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Rémi Peyronnet
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg · Bad Krozingen, Medical Center and Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Franziska Schneider-Warme
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg · Bad Krozingen, Medical Center and Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Valentina Emiliani
- Wavefront Engineering Microscopy Group, Photonics Department, Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Oded Béjà
- Faculty of Biology, Technion–Israel Institute of Technology, Haifa 32000, Israel
| | - Peter Hegemann
- Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu Berlin, Berlin, Germany
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6
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Lin YC, Ren P, Webb LJ. AMOEBA Force Field Trajectories Improve Predictions of Accurate p Ka Values of the GFP Fluorophore: The Importance of Polarizability and Water Interactions. J Phys Chem B 2022; 126:7806-7817. [PMID: 36194474 PMCID: PMC10851343 DOI: 10.1021/acs.jpcb.2c03642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Precisely quantifying the magnitude, direction, and biological functions of electric fields in proteins has long been an outstanding challenge in the field. The most widely implemented experimental method to measure such electric fields at a particular residue in a protein has been through changes in pKa of titratable residues. While many computational strategies exist to predict these values, it has been difficult to do this accurately or connect predicted results to key structural or mechanistic features of the molecule. Here, we used experimentally determined pKa values of the fluorophore in superfolder green fluorescent protein (GFP) with amino acid mutations made at position Thr 203 to evaluate the pKa prediction ability of molecular dynamics (MD) simulations using a polarizable force field, AMOEBA. Structure ensembles from AMOEBA were used to calculate pKa values of the GFP fluorophore. The calculated pKa values were then compared to trajectories using a conventional fixed charge force field (Amber03 ff). We found that the position of water molecules included in the pKa calculation had opposite effects on the pKa values between the trajectories from AMOEBA and Amber03 force fields. In AMOEBA trajectories, the inclusion of water molecules within 35 Å of the fluorophore decreased the difference between the predicted and experimental values, resulting in calculated pKa values that were within an average of 0.8 pKa unit from the experimental results. On the other hand, in Amber03 trajectories, including water molecules that were more than 5 Å from the fluorophore increased the differences between the calculated and experimental pKa values. The inaccuracy of pKa predictions determined from Amber03 trajectories was caused by a significant stabilization of the deprotonated chromophore's free energy compared to the result in AMOEBA. We rationalize the cutoffs for explicit water molecules when calculating pKa to better predict the electrostatic environment surrounding the fluorophore buried in GFP. We discuss how the results from this work will assist the prospective prediction of pKa values or other electrostatic effects in a wide variety of folded proteins.
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Affiliation(s)
- Yu-Chun Lin
- Department of Chemistry, Texas Materials Institute, and Interdisciplinary Life Sciences Program, The University of Texas at Austin, 105 E 24th St. STOP A5300, Austin, TX 78712-1224
| | - Pengyu Ren
- Department of Chemistry, Texas Materials Institute, and Interdisciplinary Life Sciences Program, The University of Texas at Austin, 105 E 24th St. STOP A5300, Austin, TX 78712-1224
| | - Lauren J. Webb
- Department of Chemistry, Texas Materials Institute, and Interdisciplinary Life Sciences Program, The University of Texas at Austin, 105 E 24th St. STOP A5300, Austin, TX 78712-1224
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7
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Dragelj J, Mroginski MA, Knapp EW. Beating Heart of Cytochrome c Oxidase: The Shared Proton of Heme a3 Propionates. J Phys Chem B 2021; 125:9668-9677. [PMID: 34427096 DOI: 10.1021/acs.jpcb.1c03619] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Cytochrome c oxidase (CcO) pumps protons from the N-side to the P-side and consumes electrons from the P-side of the mitochondrial membrane driven by energy gained from reduction of dioxygen to water. ATP synthesis uses the resulting proton gradient and electrostatic potential difference. Since the distance a proton travels through CcO is too large for a one-step transfer process, proton-loading sites (PLS) that can carry protons transiently are necessary. One specific pump-active PLS couples to the redox reaction, thus energizing the proton to move across the membrane against electric potential and proton gradient. The PLS should also prevent proton backflow. Therefore, the propionates of the two redox-active hemes in CcO were suggested as PLS candidates although, according to CcO crystal structures, none of the four propionates can be protonated on account of strong H-bonds. Here, we show that modeling the local structure around heme a3 propionates enhances significantly their capability of carrying a proton jointly. This was not possible for the propionates of heme a. The modeled structures are stable in molecular dynamics simulations (MDS) and are energetically similar to the crystal structure. Precise electrostatic energy computations of MDS data are used to estimate the pKA values of all titratable residues in CcO. For the modeled structures, the heme a3 propionates have pKA values high enough to host a proton transiently but not too high to fix the proton permanently. The change in pKA throughout the redox reaction is sufficient to push the proton to the P-side of the membrane and to provide the protons with the necessary amount of energy for ATP synthesis.
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Affiliation(s)
- Jovan Dragelj
- Freie Universität Berlin, Institute for Chemistry and Biochemistry, Fabeckstrasse 36a, 14195 Berlin, Germany.,Department of Chemistry, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Maria Andrea Mroginski
- Department of Chemistry, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Ernst Walter Knapp
- Freie Universität Berlin, Institute for Chemistry and Biochemistry, Fabeckstrasse 36a, 14195 Berlin, Germany
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8
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Baserga F, Dragelj J, Kozuch J, Mohrmann H, Knapp EW, Stripp ST, Heberle J. Quantification of Local Electric Field Changes at the Active Site of Cytochrome c Oxidase by Fourier Transform Infrared Spectroelectrochemical Titrations. Front Chem 2021; 9:669452. [PMID: 33987170 PMCID: PMC8111224 DOI: 10.3389/fchem.2021.669452] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 03/24/2021] [Indexed: 11/30/2022] Open
Abstract
Cytochrome c oxidase (CcO) is a transmembrane protein complex that reduces molecular oxygen to water while translocating protons across the mitochondrial membrane. Changes in the redox states of its cofactors trigger both O2 reduction and vectorial proton transfer, which includes a proton-loading site, yet unidentified. In this work, we exploited carbon monoxide (CO) as a vibrational Stark effect (VSE) probe at the binuclear center of CcO from Rhodobacter sphaeroides. The CO stretching frequency was monitored as a function of the electrical potential, using Fourier transform infrared (FTIR) absorption spectroelectrochemistry. We observed three different redox states (R4CO, R2CO, and O), determined their midpoint potential, and compared the resulting electric field to electrostatic calculations. A change in the local electric field strength of +2.9 MV/cm was derived, which was induced by the redox transition from R4CO to R2CO. We performed potential jump experiments to accumulate the R2CO and R4CO species and studied the FTIR difference spectra in the protein fingerprint region. The comparison of the experimental and computational results reveals that the key glutamic acid residue E286 is protonated in the observed states, and that its hydrogen-bonding environment is disturbed upon the redox transition of heme a3. Our experiments also suggest propionate A of heme a3 changing its protonation state in concert with the redox state of a second cofactor, heme a. This supports the role of propionic acid side chains as part of the proton-loading site.
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Affiliation(s)
- Federico Baserga
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
| | - Jovan Dragelj
- Macromolecular Modelling Group, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.,Modeling of Biomolecular Systems, Technische Universität Berlin, Berlin, Germany
| | - Jacek Kozuch
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
| | - Hendrik Mohrmann
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
| | - Ernst-Walter Knapp
- Macromolecular Modelling Group, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Sven T Stripp
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
| | - Joachim Heberle
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
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9
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Chen J, Hu J, Xu Y, Krasny R, Geng W. Computing Protein pKas Using the TABI Poisson–Boltzmann Solver. JOURNAL OF COMPUTATIONAL BIOPHYSICS AND CHEMISTRY 2021. [DOI: 10.1142/s2737416520420065] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A common approach to computing protein pKas uses a continuum dielectric model in which the protein is a low dielectric medium with embedded atomic point charges, the solvent is a high dielectric medium with a Boltzmann distribution of ionic charges, and the pKa is related to the electrostatic free energy which is obtained by solving the Poisson–Boltzmann equation. Starting from the model pKa for a titrating residue, the method obtains the intrinsic pKa and then computes the protonation probability for a given pH including site–site interactions. This approach assumes that acid dissociation does not affect protein conformation aside from adding or deleting charges at titratable sites. In this work, we demonstrate our treecode-accelerated boundary integral (TABI) solver for the relevant electrostatic calculations. The pKa computing procedure is enclosed in a convenient Python wrapper which is publicly available at the corresponding author’s website. Predicted results are compared with experimental pKas for several proteins. Among ongoing efforts to improve protein pKa calculations, the advantage of TABI is that it reduces the numerical errors in the electrostatic calculations so that attention can be focused on modeling assumptions.
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Affiliation(s)
- Jiahui Chen
- Department of Mathematics, Michigan State University, East Lansing, MI 48824, USA
| | - Jingzhen Hu
- Department of Mathematics, Duke University, Durham, NC 27710, USA
| | - Yongjia Xu
- Department of Mathematics, Southern Methodist University, Dallas, TX 75275, USA
| | - Robert Krasny
- Department of Mathematics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Weihua Geng
- Department of Mathematics, Southern Methodist University, Dallas, TX 75275, USA
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10
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Kruse F, Nguyen AD, Dragelj J, Heberle J, Hildebrandt P, Mroginski MA, Weidinger IM. A Resonance Raman Marker Band Characterizes the Slow and Fast Form of Cytochrome c Oxidase. J Am Chem Soc 2021; 143:2769-2776. [PMID: 33560128 DOI: 10.1021/jacs.0c10767] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Cytochrome c oxidase (CcO) in its as-isolated form is known to exist in a slow and fast form, which differ drastically in their ability to bind oxygen and other ligands. While preparation methods have been established that yield either the fast or the slow form of the protein, the underlying structural differences have not been identified yet. Here, we have performed surface enhanced resonance Raman (SERR) spectroscopy of CcO immobilized on electrodes in both forms. SERR spectra obtained in resonance with the heme a3 metal-to-ligand charge transfer (MLCT) transition at 650 nm displayed a sharp vibrational band at 748 or 750 cm-1 when the protein was in its slow or fast form, respectively. DFT calculations identified the band as a mode of the His-419 ligand that is sensitive to the oxygen ligand and the protonation state of Tyr-288 within the binuclear complex. Potential-dependent SERR spectroscopy showed a redox-induced change of this band around 525 mV versus Ag/AgCl exclusively for the fast form, which coincides with the redox potential of the Tyr-O/Tyr-O- transition. Our data points to a peroxide ligand in the resting state of CcO for both forms. The observed frequencies and redox sensitivities of the Raman marker band suggest that a radical Tyr-288 is present in the fast form and a protonated Tyr-288 in the slow form.
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Affiliation(s)
- Fabian Kruse
- Department of Chemistry and Food Chemistry, Technische Universität Dresden, 01069 Dresden, Germany
| | - Anh Duc Nguyen
- Department of Chemistry, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Jovan Dragelj
- Department of Chemistry, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Joachim Heberle
- Freie Universität Berlin, Department of Physics, Experimental Molecular Biophysics, Arnimallee 14, 14195 Berlin, Germany
| | - Peter Hildebrandt
- Department of Chemistry, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Maria Andrea Mroginski
- Department of Chemistry, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Inez M Weidinger
- Department of Chemistry and Food Chemistry, Technische Universität Dresden, 01069 Dresden, Germany
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11
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Mroginski MA, Adam S, Amoyal GS, Barnoy A, Bondar AN, Borin VA, Church JR, Domratcheva T, Ensing B, Fanelli F, Ferré N, Filiba O, Pedraza-González L, González R, González-Espinoza CE, Kar RK, Kemmler L, Kim SS, Kongsted J, Krylov AI, Lahav Y, Lazaratos M, NasserEddin Q, Navizet I, Nemukhin A, Olivucci M, Olsen JMH, Pérez de Alba Ortíz A, Pieri E, Rao AG, Rhee YM, Ricardi N, Sen S, Solov'yov IA, De Vico L, Wesolowski TA, Wiebeler C, Yang X, Schapiro I. Frontiers in Multiscale Modeling of Photoreceptor Proteins. Photochem Photobiol 2021; 97:243-269. [PMID: 33369749 DOI: 10.1111/php.13372] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 11/01/2020] [Indexed: 02/06/2023]
Abstract
This perspective article highlights the challenges in the theoretical description of photoreceptor proteins using multiscale modeling, as discussed at the CECAM workshop in Tel Aviv, Israel. The participants have identified grand challenges and discussed the development of new tools to address them. Recent progress in understanding representative proteins such as green fluorescent protein, photoactive yellow protein, phytochrome, and rhodopsin is presented, along with methodological developments.
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Affiliation(s)
| | - Suliman Adam
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Gil S Amoyal
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Avishai Barnoy
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ana-Nicoleta Bondar
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics Group, Berlin, Germany
| | - Veniamin A Borin
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Jonathan R Church
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Tatiana Domratcheva
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia.,Department Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Bernd Ensing
- Van 't Hoff Institute for Molecular Science and Amsterdam Center for Multiscale Modeling, University of Amsterdam, Amsterdam, The Netherlands
| | - Francesca Fanelli
- Department of Life Sciences, Center for Neuroscience and Neurotechnology, Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | | | - Ofer Filiba
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Laura Pedraza-González
- Department of Biotechnology, Chemistry and Pharmacy, Università degli Studi di Siena, Siena, Italy
| | - Ronald González
- Institut für Chemie, Technische Universität Berlin, Berlin, Germany
| | | | - Rajiv K Kar
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Lukas Kemmler
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics Group, Berlin, Germany
| | - Seung Soo Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon, Korea
| | - Jacob Kongsted
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Anna I Krylov
- Department of Chemistry, University of Southern California, Los Angeles, CA, USA
| | - Yigal Lahav
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel.,MIGAL - Galilee Research Institute, S. Industrial Zone, Kiryat Shmona, Israel
| | - Michalis Lazaratos
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics Group, Berlin, Germany
| | - Qays NasserEddin
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Isabelle Navizet
- MSME, Univ Gustave Eiffel, CNRS UMR 8208, Univ Paris Est Creteil, Marne-la-Vallée, France
| | - Alexander Nemukhin
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia.,Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Massimo Olivucci
- Department of Biotechnology, Chemistry and Pharmacy, Università degli Studi di Siena, Siena, Italy.,Chemistry Department, Bowling Green State University, Bowling Green, OH, USA
| | - Jógvan Magnus Haugaard Olsen
- Department of Chemistry, Aarhus University, Aarhus, Denmark.,Department of Chemistry, Hylleraas Centre for Quantum Molecular Sciences, UiT The Arctic University of Norway, Tromsø, Norway
| | - Alberto Pérez de Alba Ortíz
- Van 't Hoff Institute for Molecular Science and Amsterdam Center for Multiscale Modeling, University of Amsterdam, Amsterdam, The Netherlands
| | - Elisa Pieri
- Aix-Marseille Univ, CNRS, ICR, Marseille, France
| | - Aditya G Rao
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Young Min Rhee
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon, Korea
| | - Niccolò Ricardi
- Département de Chimie Physique, Université de Genève, Genève, Switzerland
| | - Saumik Sen
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ilia A Solov'yov
- Department of Physics, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Luca De Vico
- Department of Biotechnology, Chemistry and Pharmacy, Università degli Studi di Siena, Siena, Italy
| | | | - Christian Wiebeler
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Xuchun Yang
- Chemistry Department, Bowling Green State University, Bowling Green, OH, USA
| | - Igor Schapiro
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
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12
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Elghobashi-Meinhardt N, Tombolelli D, Mroginski MA. QM/MM computations reveal details of the acetyl-CoA synthase catalytic center. Biochim Biophys Acta Gen Subj 2020; 1864:129579. [DOI: 10.1016/j.bbagen.2020.129579] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 01/31/2020] [Accepted: 02/22/2020] [Indexed: 10/24/2022]
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13
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Cholesterol Transport in Wild-Type NPC1 and P691S: Molecular Dynamics Simulations Reveal Changes in Dynamical Behavior. Int J Mol Sci 2020; 21:ijms21082962. [PMID: 32331453 PMCID: PMC7215871 DOI: 10.3390/ijms21082962] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/14/2020] [Accepted: 04/15/2020] [Indexed: 12/22/2022] Open
Abstract
The Niemann–Pick C1 (NPC1) protein is the main protein involved in NPC disease, a fatal lysosomal lipid storage disease. NPC1, containing 1278 amino acids, is comprised of three lumenal domains (N-terminal, middle lumenal, C-terminal) and a transmembrane (TM) domain that contains a five helix bundle referred to as the sterol-sensing domain (SSD). The exact purpose of the SSD is not known, but it is believed that the SSD may bind cholesterol, either as a part of the lipid trafficking pathway or as part of a signaling mechanism. A recent cryo-EM structure has revealed an itraconazole binding site (IBS) in the SSD of human NPC1. Using this structural data, we constructed a model of cholesterol-bound wild-type (WT) and mutant P691S and performed molecular dynamics (MD) simulations of each cholesterol-bound protein. For WT NPC1, cholesterol migrates laterally, in the direction of the lipid bilayer. In the case of P691S, cholesterol is observed for the first time to migrate away from the SSD toward the N-terminal domain via a putative tunnel that connects the IBS with the lumenal domains. Structural features of the IBS are analyzed to identify the causes for different dynamical behavior between cholesterol-bound WT and cholesterol-bound P691S. The side chain of Ser691 in the P691S mutant introduces a hydrogen bond network that is not present in the WT protein. This change is likely responsible for the altered dynamical behavior observed in the P691S mutant and helps explain the disrupted cholesterol trafficking behavior observed in experiments.
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14
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Schuller JM, Saura P, Thiemann J, Schuller SK, Gamiz-Hernandez AP, Kurisu G, Nowaczyk MM, Kaila VRI. Redox-coupled proton pumping drives carbon concentration in the photosynthetic complex I. Nat Commun 2020; 11:494. [PMID: 31980611 PMCID: PMC6981117 DOI: 10.1038/s41467-020-14347-4] [Citation(s) in RCA: 44] [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: 10/13/2019] [Accepted: 12/22/2019] [Indexed: 11/25/2022] Open
Abstract
Photosynthetic organisms capture light energy to drive their energy metabolism, and employ the chemical reducing power to convert carbon dioxide (CO2) into organic molecules. Photorespiration, however, significantly reduces the photosynthetic yields. To survive under low CO2 concentrations, cyanobacteria evolved unique carbon-concentration mechanisms that enhance the efficiency of photosynthetic CO2 fixation, for which the molecular principles have remained unknown. We show here how modular adaptations enabled the cyanobacterial photosynthetic complex I to concentrate CO2 using a redox-driven proton-pumping machinery. Our cryo-electron microscopy structure at 3.2 Å resolution shows a catalytic carbonic anhydrase module that harbours a Zn2+ active site, with connectivity to proton-pumping subunits that are activated by electron transfer from photosystem I. Our findings illustrate molecular principles in the photosynthetic complex I machinery that enabled cyanobacteria to survive in drastically changing CO2 conditions.
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Affiliation(s)
- Jan M Schuller
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany.
| | - Patricia Saura
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91, Stockholm, Sweden
- Center of Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Garching, Germany
| | - Jacqueline Thiemann
- Plant Biochemistry, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44780, Bochum, Germany
| | - Sandra K Schuller
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Ana P Gamiz-Hernandez
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91, Stockholm, Sweden
- Center of Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Garching, Germany
| | - Genji Kurisu
- Institute for Protein Research, Osaka University, Suita, Osaka, 565-0871, Japan
- Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, 560-0043, Japan
| | - Marc M Nowaczyk
- Plant Biochemistry, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44780, Bochum, Germany.
| | - Ville R I Kaila
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91, Stockholm, Sweden.
- Center of Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Garching, Germany.
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15
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Oppermann J, Fischer P, Silapetere A, Liepe B, Rodriguez-Rozada S, Flores-Uribe J, Schiewer E, Keidel A, Vierock J, Kaufmann J, Broser M, Luck M, Bartl F, Hildebrandt P, Wiegert JS, Béjà O, Hegemann P, Wietek J. MerMAIDs: a family of metagenomically discovered marine anion-conducting and intensely desensitizing channelrhodopsins. Nat Commun 2019; 10:3315. [PMID: 31346176 PMCID: PMC6658528 DOI: 10.1038/s41467-019-11322-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 06/24/2019] [Indexed: 01/07/2023] Open
Abstract
Channelrhodopsins (ChRs) are algal light-gated ion channels widely used as optogenetic tools for manipulating neuronal activity. ChRs desensitize under continuous bright-light illumination, resulting in a significant decline of photocurrents. Here we describe a metagenomically identified family of phylogenetically distinct anion-conducting ChRs (designated MerMAIDs). MerMAIDs almost completely desensitize during continuous illumination due to accumulation of a late non-conducting photointermediate that disrupts the ion permeation pathway. MerMAID desensitization can be fully explained by a single photocycle in which a long-lived desensitized state follows the short-lived conducting state. A conserved cysteine is the critical factor in desensitization, as its mutation results in recovery of large stationary photocurrents. The rapid desensitization of MerMAIDs enables their use as optogenetic silencers for transient suppression of individual action potentials without affecting subsequent spiking during continuous illumination. Our results could facilitate the development of optogenetic tools from metagenomic databases and enhance general understanding of ChR function.
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Affiliation(s)
- Johannes Oppermann
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Paul Fischer
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Arita Silapetere
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Bernhard Liepe
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Silvia Rodriguez-Rozada
- Research Group Synaptic Wiring and Information Processing, Center for Molecular Neurobiology Hamburg, Falkenried 94, 20251, Hamburg, Germany
| | - José Flores-Uribe
- Technion-Israel Institute of Technology, 32000, Haifa, Israel
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, 50829, Germany
| | - Enrico Schiewer
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Anke Keidel
- Institute for Chemistry, Physical Chemistry/Biophysical Chemistry, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - Johannes Vierock
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Joel Kaufmann
- Institute for Biology, Biophysical Chemistry, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Matthias Broser
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Meike Luck
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Franz Bartl
- Institute for Biology, Biophysical Chemistry, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Peter Hildebrandt
- Institute for Chemistry, Physical Chemistry/Biophysical Chemistry, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - J Simon Wiegert
- Research Group Synaptic Wiring and Information Processing, Center for Molecular Neurobiology Hamburg, Falkenried 94, 20251, Hamburg, Germany
| | - Oded Béjà
- Technion-Israel Institute of Technology, 32000, Haifa, Israel
| | - Peter Hegemann
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany.
| | - Jonas Wietek
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany.
- Department of Neurobiology, Weizmann Institute of Science, 7610001, Rehovot, Israel.
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16
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Sakipov SN, Flores-Canales JC, Kurnikova MG. A Hierarchical Approach to Predict Conformation-Dependent Histidine Protonation States in Stable and Flexible Proteins. J Phys Chem B 2019; 123:5024-5034. [PMID: 31095377 DOI: 10.1021/acs.jpcb.9b00656] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Solution acidity measured by pH is an important environmental factor that affects protein structure. It influences the protonation state of protein residues, which in turn may be coupled to protein conformational changes, unfolding, and ligand binding. It remains difficult to compute and measure the p Ka of individual residues, as well as to relate them to pH-dependent protein transitions. This paper presents a hierarchical approach to compute the p Ka of individual protonatable residues, specifically histidines, coupled with underlying structural changes of a protein. A fast and efficient free energy perturbation (FEP) algorithm has also been developed utilizing a fast implementation of standard molecular dynamics (MD) algorithms. Specifically, a CUDA version of the AMBER MD engine is used in this paper. Eight histidine p Ka's are computed in a diverse set of pH stable proteins to demonstrate the proposed approach's utility and assess the predictive quality of the AMBER FF99SB force field. A reference molecule is carefully selected and tested for convergence. A hierarchical approach is used to model p Ka's of the six histidine residues of the diphtheria toxin translocation domain (DTT), which exhibits a diverse ensemble of individual conformations and pH-dependent unfolding. The hierarchical approach consists of first sampling equilibrium conformational ensembles of a protein with protonated and neutral histidine residues via long equilibrium MD simulations (Flores-Canales, J. C.; et al. bioRxiv, 2019, 572040). A clustering method is then used to identify sampled protein conformations, and p Ka's of histidines in each protein conformation are computed. Finally, an ensemble averaging formalism is developed to compute weighted average histidine p Ka's. These can be compared with an apparent experimentally measured p Ka of the DTT protein and thus allows us to propose a mechanism of pH-dependent unfolding of the DTT protein.
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Affiliation(s)
- Serzhan N Sakipov
- Chemistry Department , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Jose C Flores-Canales
- Chemistry Department , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Maria G Kurnikova
- Chemistry Department , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
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17
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Chen A, Xu T, Ge Y, Wang L, Tang W, Li S. Hydrogen-bond-based protein engineering for the acidic adaptation of Bacillus acidopullulyticus pullulanase. Enzyme Microb Technol 2019; 124:79-83. [DOI: 10.1016/j.enzmictec.2019.01.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 01/12/2019] [Accepted: 01/29/2019] [Indexed: 01/05/2023]
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18
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Elghobashi-Meinhardt N. Computational Tools Unravel Putative Sterol Binding Sites in the Lysosomal NPC1 Protein. J Chem Inf Model 2019; 59:2432-2441. [PMID: 30942586 DOI: 10.1021/acs.jcim.9b00186] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Two proteins have been linked as the critical components in the molecular mechanisms involved in the Niemann Pick type C (NPC) disease: NPC1, a 140 kDa polytopic membrane-bound protein, and the smaller (132 residues), water-soluble NPC2 protein. NPC1 is believed to act in tandem with NPC2, transferring cholesterol and other sterols out of the LE/Lys compartments. Mutations in either NPC1 or NPC2 can lead to an accumulation of cholesterol and lipids in the LE/Lys, the primary phenotype of the NPC disease, but approximately 95% of identified disease-causing mutations have been mapped to the membrane-bound NPC1 protein. Here, we investigate the full length, membrane-bound NPC1 protein computationally using a combination of molecular modeling, docking, and molecular dynamics (MD) simulations. An analysis of titratable amino acid side chains, several buried in protein pockets, reveals several nonstandard protonation states for the low-pH scenario (pH 5) that is realized in the lysosome. Together with the location of these buried amino acids, docking studies have identified putative lipid binding domains that are in close proximity to amino acids that, when mutated, are connected to NPC1 loss-of-function. Using energy analyses and MD simulations, we analyze these domains as potential cholesterol binding sites and propose the possibility of multiple sterol binding pockets enabling the intramolecular transport of sterol molecules to the transmembrane domain.
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19
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Farahvash A, Leontyev I, Stuchebrukhov A. Dynamic and Electronic Polarization Corrections to the Dielectric Constant of Water. J Phys Chem A 2018; 122:9243-9250. [DOI: 10.1021/acs.jpca.8b07953] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ardavan Farahvash
- Department of Chemistry, University of California Davis, One Shields Avenue, Davis, California 95616, United States
| | - Igor Leontyev
- Department of Chemistry, University of California Davis, One Shields Avenue, Davis, California 95616, United States
| | - Alexei Stuchebrukhov
- Department of Chemistry, University of California Davis, One Shields Avenue, Davis, California 95616, United States
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20
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Abstract
Complex I couples the free energy released from quinone (Q) reduction to pump protons across the biological membrane in the respiratory chains of mitochondria and many bacteria. The Q reduction site is separated by a large distance from the proton-pumping membrane domain. To address the molecular mechanism of this long-range proton-electron coupling, we perform here full atomistic molecular dynamics simulations, free energy calculations, and continuum electrostatics calculations on complex I from Thermus thermophilus We show that the dynamics of Q is redox-state-dependent, and that quinol, QH2, moves out of its reduction site and into a site in the Q tunnel that is occupied by a Q analog in a crystal structure of Yarrowia lipolytica We also identify a second Q-binding site near the opening of the Q tunnel in the membrane domain, where the Q headgroup forms strong interactions with a cluster of aromatic and charged residues, while the Q tail resides in the lipid membrane. We estimate the effective diffusion coefficient of Q in the tunnel, and in turn the characteristic time for Q to reach the active site and for QH2 to escape to the membrane. Our simulations show that Q moves along the Q tunnel in a redox-state-dependent manner, with distinct binding sites formed by conserved residue clusters. The motion of Q to these binding sites is proposed to be coupled to the proton-pumping machinery in complex I.
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21
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Rossini E, Bochevarov AD, Knapp EW. Empirical Conversion of p K a Values between Different Solvents and Interpretation of the Parameters: Application to Water, Acetonitrile, Dimethyl Sulfoxide, and Methanol. ACS OMEGA 2018; 3:1653-1662. [PMID: 31458485 PMCID: PMC6641400 DOI: 10.1021/acsomega.7b01895] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 01/26/2018] [Indexed: 05/08/2023]
Abstract
An empirical conversion method (ECM) that transforms pK a values of arbitrary organic compounds from one solvent to the other is introduced. We demonstrate the method's usefulness and performance on pK a conversions involving water and organic solvents acetonitrile (MeCN), dimethyl sulfoxide (Me2SO), and methanol (MeOH). We focus on the pK a conversion from the known reference value in water to the other three organic solvents, although such a conversion can also be performed between any pair of the considered solvents. The ECM works with an additive parameter that is specific to a solvent and a molecular family (essentially characterized by a functional group that is titrated). We formally show that the method can be formulated with a single additive parameter, and that the extra multiplicative parameter used in other works is not required. The values of the additive parameter are determined from known pK a data, and their interpretation is provided on the basis of physicochemical concepts. The data set of known pK a values is augmented with pK a values computed with the recently introduced electrostatic transform method, whose validity is demonstrated. For a validation of our method, we consider pK a conversions for two data sets of titratable compounds. The first data set involves 81 relatively small molecules belonging to 19 different molecular families, with the pK a data available in all four considered solvents. The second data set involves 76 titratable molecules from 5 additional molecular families. These molecules are typically larger, and their experimental pK a values are available only in Me2SO and water. The validation tests show that the agreement between the experimental pK a data and the ECM predictions is generally good, with absolute errors often on the order of 0.5 pH units. The presence of a few outliers is rationalized, and observed trends with respect to molecular families are discussed.
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Affiliation(s)
- Emanuele Rossini
- Freie
Universität Berlin, Institute of
Chemistry and Biochemistry, Fabeck Strasse 36A, Berlin D-14195, Germany
- Theoretical
Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, Frankfurt a. M. 60438, Germany
| | - Art D. Bochevarov
- Schrödinger
Inc, 120 West 45th Street,
17th floor, New York, New
York 10036, United
States
| | - Ernst Walter Knapp
- Freie
Universität Berlin, Institute of
Chemistry and Biochemistry, Fabeck Strasse 36A, Berlin D-14195, Germany
- E-mail: (E.W.K.)
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22
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Batebi H, Dragelj J, Imhof P. Role of AP-endonuclease (Ape1) active site residues in stabilization of the reactant enzyme-DNA complex. Proteins 2018; 86:439-453. [PMID: 29344998 DOI: 10.1002/prot.25460] [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: 08/02/2017] [Revised: 01/08/2018] [Accepted: 01/11/2018] [Indexed: 11/11/2022]
Abstract
Apurinic/apyrimidinic endonuclease 1 (Ape1) is an important metal-dependent enzyme in the base excision repair mechanism, responsible for the backbone cleavage of abasic DNA through a phosphate hydrolysis reaction. Molecular dynamics simulations of Ape1 complexed to its substrate DNA performed for models containing 1 or 2 Mg2+ -ions as cofactor located at different positions show a complex with 1 metal ion bound on the leaving group site of the scissile phosphate to be the most likely reaction-competent conformation. Active-site residue His309 is found to be protonated based on pKa calculations and the higher conformational stability of the Ape1-DNA substrate complex compared to scenarios with neutral His309. Simulations of the D210N mutant further support the prevalence of protonated His309 and strongly suggest Asp210 as the general base for proton acceptance by a nucleophilic water molecule.
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Affiliation(s)
- Hossein Batebi
- Department of Physics, Institute of Theoretical Physics, Freie Universität Berlin, Arnimallee 14, Berlin, 14195, Germany
| | - Jovan Dragelj
- Department of Biology, Chemistry, and Pharmacy, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Fabeckstrasse 36A, Berlin, 14195, Germany
| | - Petra Imhof
- Department of Physics, Institute of Theoretical Physics, Freie Universität Berlin, Arnimallee 14, Berlin, 14195, Germany
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23
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Zhu G, Liu W, Bao C, Tong D, Ji H, Shen Z, Yang D, Lu L. Investigating energy-based pool structure selection in the structure ensemble modeling with experimental distance constraints: The example from a multidomain protein Pub1. Proteins 2018; 86:501-514. [PMID: 29383828 DOI: 10.1002/prot.25468] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 12/26/2017] [Accepted: 01/23/2018] [Indexed: 12/25/2022]
Abstract
The structural variations of multidomain proteins with flexible parts mediate many biological processes, and a structure ensemble can be determined by selecting a weighted combination of representative structures from a simulated structure pool, producing the best fit to experimental constraints such as interatomic distance. In this study, a hybrid structure-based and physics-based atomistic force field with an efficient sampling strategy is adopted to simulate a model di-domain protein against experimental paramagnetic relaxation enhancement (PRE) data that correspond to distance constraints. The molecular dynamics simulations produce a wide range of conformations depicted on a protein energy landscape. Subsequently, a conformational ensemble recovered with low-energy structures and the minimum-size restraint is identified in good agreement with experimental PRE rates, and the result is also supported by chemical shift perturbations and small-angle X-ray scattering data. It is illustrated that the regularizations of energy and ensemble-size prevent an arbitrary interpretation of protein conformations. Moreover, energy is found to serve as a critical control to refine the structure pool and prevent data overfitting, because the absence of energy regularization exposes ensemble construction to the noise from high-energy structures and causes a more ambiguous representation of protein conformations. Finally, we perform structure-ensemble optimizations with a topology-based structure pool, to enhance the understanding on the ensemble results from different sources of pool candidates.
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Affiliation(s)
- Guanhua Zhu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
| | - Wei Liu
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore
| | - Chenglong Bao
- Department of Mathematics, National University of Singapore, 10 Lower Kent Ridge Road, Singapore, 119076, Singapore.,Yau Mathematical Sciences Center, Tsinghua University, Haidian District, Beijing, 100084, China
| | - Dudu Tong
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
| | - Hui Ji
- Department of Mathematics, National University of Singapore, 10 Lower Kent Ridge Road, Singapore, 119076, Singapore
| | - Zuowei Shen
- Department of Mathematics, National University of Singapore, 10 Lower Kent Ridge Road, Singapore, 119076, Singapore
| | - Daiwen Yang
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore
| | - Lanyuan Lu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
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24
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Zhou HX, Pang X. Electrostatic Interactions in Protein Structure, Folding, Binding, and Condensation. Chem Rev 2018; 118:1691-1741. [PMID: 29319301 DOI: 10.1021/acs.chemrev.7b00305] [Citation(s) in RCA: 477] [Impact Index Per Article: 79.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Charged and polar groups, through forming ion pairs, hydrogen bonds, and other less specific electrostatic interactions, impart important properties to proteins. Modulation of the charges on the amino acids, e.g., by pH and by phosphorylation and dephosphorylation, have significant effects such as protein denaturation and switch-like response of signal transduction networks. This review aims to present a unifying theme among the various effects of protein charges and polar groups. Simple models will be used to illustrate basic ideas about electrostatic interactions in proteins, and these ideas in turn will be used to elucidate the roles of electrostatic interactions in protein structure, folding, binding, condensation, and related biological functions. In particular, we will examine how charged side chains are spatially distributed in various types of proteins and how electrostatic interactions affect thermodynamic and kinetic properties of proteins. Our hope is to capture both important historical developments and recent experimental and theoretical advances in quantifying electrostatic contributions of proteins.
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Affiliation(s)
- Huan-Xiang Zhou
- Department of Chemistry and Department of Physics, University of Illinois at Chicago , Chicago, Illinois 60607, United States.,Department of Physics and Institute of Molecular Biophysics, Florida State University , Tallahassee, Florida 32306, United States
| | - Xiaodong Pang
- Department of Physics and Institute of Molecular Biophysics, Florida State University , Tallahassee, Florida 32306, United States
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25
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Yu D, Du R, Xiao JC, Xu S, Rong C, Liu S. Theoretical Study of pKa Values for Trivalent Rare-Earth Metal Cations in Aqueous Solution. J Phys Chem A 2018; 122:700-707. [DOI: 10.1021/acs.jpca.7b12074] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Donghai Yu
- Key
Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic
Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
- Key
Laboratory of Chemical Biology and Traditional Chinese Medicine Research
(Ministry of Education of China), College of Chemistry and Chemical
Engineering, Hunan Normal University, Changsha, Hunan 410081, China
| | - Ruobing Du
- Key
Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic
Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Ji-Chang Xiao
- Key
Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic
Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Shengming Xu
- Institute
of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
| | - Chunying Rong
- Key
Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic
Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Shubin Liu
- Research
Computing Center, University of North Carolina, Chapel Hill, North Carolina 27599-3420, United States
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26
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Mohrmann H, Dragelj J, Baserga F, Knapp EW, Stripp ST, Heberle J. The reductive phase of Rhodobacter sphaeroides cytochrome c oxidase disentangled by CO ligation. Phys Chem Chem Phys 2017. [PMID: 29067359 DOI: 10.1039/c7cp06480b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cytochrome c oxidase (CcO) is a membrane protein of the respiratory chain that catalytically reduces molecular oxygen (O2) to water while translocating protons across the membrane. The enzyme hosts two copper and two heme iron moieties (heme a/heme a3). The atomic details of the sequential steps that go along with this redox-driven proton translocation are a matter of debate. Particularly for the reductive phase of CcO that precedes oxygen binding experimental data are scarce. Here, we use CcO under anaerobic conditions where carbon monoxide (CO) is bound to heme a3 which in tandem with CuB forms the binuclear center (BNC). Fourier-transform infrared (FTIR) absorption spectroscopy is combined with electro-chemistry to probe different redox and protonation states populated by variation of the external electrostatic potential. With this approach, the redox behavior of heme a and the BNC could be separated and the corresponding redox potentials were determined. We also infer the protonation of one of the propionate side chains of heme a3 to correlate with the oxidation of heme a. Experimental changes in the local electric field surrounding CO bound to heme a3 are determined by their vibrational Stark effect and agree well with electrostatic computations. The comparison of experimental and computational results indicates that changes of the heme a3/CuB redox state are coupled to proton transfer towards heme a3. The latter supports the role of the heme a3 propionate D as proton loading site.
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Affiliation(s)
- Hendrik Mohrmann
- Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | - Jovan Dragelj
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Fabeckstraße 36A, 14195 Berlin, Germany
| | - Federico Baserga
- Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | - Ernst-Walter Knapp
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Fabeckstraße 36A, 14195 Berlin, Germany
| | - Sven T Stripp
- Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | - Joachim Heberle
- Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
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27
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Slocum JD, First JT, Webb LJ. Orthogonal Electric Field Measurements near the Green Fluorescent Protein Fluorophore through Stark Effect Spectroscopy and pKa Shifts Provide a Unique Benchmark for Electrostatics Models. J Phys Chem B 2017. [DOI: 10.1021/acs.jpcb.7b03935] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Joshua D. Slocum
- Department of Chemistry,
Center for Nano and Molecular Science and Technology, and Institute
for Cell and Molecular Biology, The University of Texas at Austin, 105
E 24th St. STOP A5300, Austin, Texas 78712-1224, United States
| | - Jeremy T. First
- Department of Chemistry,
Center for Nano and Molecular Science and Technology, and Institute
for Cell and Molecular Biology, The University of Texas at Austin, 105
E 24th St. STOP A5300, Austin, Texas 78712-1224, United States
| | - Lauren J. Webb
- Department of Chemistry,
Center for Nano and Molecular Science and Technology, and Institute
for Cell and Molecular Biology, The University of Texas at Austin, 105
E 24th St. STOP A5300, Austin, Texas 78712-1224, United States
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28
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Li L, Chakravorty A, Alexov E. DelPhiForce, a tool for electrostatic force calculations: Applications to macromolecular binding. J Comput Chem 2017; 38:584-593. [PMID: 28130775 PMCID: PMC5315605 DOI: 10.1002/jcc.24715] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 12/10/2016] [Indexed: 12/31/2022]
Abstract
Long-range electrostatic forces play an important role in molecular biology, particularly in macromolecular interactions. However, calculating the electrostatic forces for irregularly shaped molecules immersed in water is a difficult task. Here, we report a new tool, DelPhiForce, which is a tool in the DelPhi package that calculates and visualizes the electrostatic forces in biomolecular systems. In parallel, the DelPhi algorithm for modeling electrostatic potential at user-defined positions has been enhanced to include triquadratic and tricubic interpolation methods. The tricubic interpolation method has been tested against analytical solutions and it has been demonstrated that the corresponding errors are negligibly small at resolution 4 grids/Å. The DelPhiForce is further applied in the study of forces acting between partners of three protein-protein complexes. It has been demonstrated that electrostatic forces play a dual role by steering binding partners (so that the partners recognize their native interfaces) and exerting an electrostatic torque (if the mutual orientations of the partners are not native-like). The output of DelPhiForce is in a format that VMD can read and visualize, and provides additional options for analysis of protein-protein binding. DelPhiForce is available for download from the DelPhi webpage at http://compbio.clemson.edu/downloadDir/delphiforce.tar.gz © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Lin Li
- Department of Physics, Clemson University, Clemson, SC 29634, USA
| | | | - Emil Alexov
- Department of Physics, Clemson University, Clemson, SC 29634, USA
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29
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Stenrup M, Pieri E, Ledentu V, Ferré N. pH-Dependent absorption spectrum of a protein: a minimal electrostatic model of Anabaena sensory rhodopsin. Phys Chem Chem Phys 2017; 19:14073-14084. [DOI: 10.1039/c7cp00991g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A minimal electrostatic model is introduced which aims at reproducing and analyzing the visible-light absorption energy shift of a protein with pH.
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30
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Bochevarov AD, Watson MA, Greenwood JR, Philipp DM. Multiconformation, Density Functional Theory-Based pKa Prediction in Application to Large, Flexible Organic Molecules with Diverse Functional Groups. J Chem Theory Comput 2016; 12:6001-6019. [PMID: 27951674 DOI: 10.1021/acs.jctc.6b00805] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Art D. Bochevarov
- Schrödinger, Inc., 120 West 45th Street, New York, New York 10036, United States
| | - Mark A. Watson
- Schrödinger, Inc., 120 West 45th Street, New York, New York 10036, United States
| | - Jeremy R. Greenwood
- Schrödinger, Inc., 120 West 45th Street, New York, New York 10036, United States
| | - Dean M. Philipp
- Schrödinger, Inc., 101 SW Main Street, Suite 1300, Portland, Oregon 97204, United States
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31
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Gunner MR, Baker NA. Continuum Electrostatics Approaches to Calculating pKas and Ems in Proteins. Methods Enzymol 2016; 578:1-20. [PMID: 27497160 DOI: 10.1016/bs.mie.2016.05.052] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Proteins change their charge state through protonation and redox reactions as well as through binding charged ligands. The free energy of these reactions is dominated by solvation and electrostatic energies and modulated by protein conformational relaxation in response to the ionization state changes. Although computational methods for calculating these interactions can provide very powerful tools for predicting protein charge states, they include several critical approximations of which users should be aware. This chapter discusses the strengths, weaknesses, and approximations of popular computational methods for predicting charge states and understanding the underlying electrostatic interactions. The goal of this chapter is to inform users about applications and potential caveats of these methods as well as outline directions for future theoretical and computational research.
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Affiliation(s)
- M R Gunner
- City College of New York in the City University of New York, New York, United States.
| | - N A Baker
- Pacific Northwest National Laboratory, Richland, DC, United States; Brown University, Providence, RI, United States
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32
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Yu D, Du R, Xiao JC. pK
a prediction for acidic phosphorus-containing compounds using multiple linear regression with computational descriptors. J Comput Chem 2016; 37:1668-71. [DOI: 10.1002/jcc.24381] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 01/12/2016] [Accepted: 03/05/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Donghai Yu
- Key Laboratory of Organofluorine Chemistry; Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences; Shanghai China
| | - Ruobing Du
- Key Laboratory of Organofluorine Chemistry; Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences; Shanghai China
| | - Ji-Chang Xiao
- Key Laboratory of Organofluorine Chemistry; Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences; Shanghai China
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33
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Sakalli I, Knapp EW. pK(A) in proteins solving the Poisson-Boltzmann equation with finite elements. J Comput Chem 2015; 36:2147-57. [PMID: 26284944 DOI: 10.1002/jcc.24053] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 06/24/2015] [Accepted: 07/30/2015] [Indexed: 11/12/2022]
Abstract
Knowledge on pK(A) values is an eminent factor to understand the function of proteins in living systems. We present a novel approach demonstrating that the finite element (FE) method of solving the linearized Poisson-Boltzmann equation (lPBE) can successfully be used to compute pK(A) values in proteins with high accuracy as a possible replacement to finite difference (FD) method. For this purpose, we implemented the software molecular Finite Element Solver (mFES) in the framework of the Karlsberg+ program to compute pK(A) values. This work focuses on a comparison between pK(A) computations obtained with the well-established FD method and with the new developed FE method mFES, solving the lPBE using protein crystal structures without conformational changes. Accurate and coarse model systems are set up with mFES using a similar number of unknowns compared with the FD method. Our FE method delivers results for computations of pK(A) values and interaction energies of titratable groups, which are comparable in accuracy. We introduce different thermodynamic cycles to evaluate pK(A) values and we show for the FE method how different parameters influence the accuracy of computed pK(A) values.
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Affiliation(s)
- Ilkay Sakalli
- Freie Universität Berlin, Department of Biology, Chemistry and Pharmacy, Institute of Chemistry and Biochemistry, Fabeckstr. 36a, 14195, Berlin, Germany
| | - Ernst-Walter Knapp
- Freie Universität Berlin, Department of Biology, Chemistry and Pharmacy, Institute of Chemistry and Biochemistry, Fabeckstr. 36a, 14195, Berlin, Germany
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