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Ramanthrikkovil Variyam A, Rzycki M, Yucknovsky A, Stuchebrukhov AA, Drabik D, Amdursky N. Proton diffusion on the surface of mixed lipid membranes highlights the role of membrane composition. Biophys J 2024:S0006-3495(24)00441-7. [PMID: 38961623 DOI: 10.1016/j.bpj.2024.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 06/13/2024] [Accepted: 07/01/2024] [Indexed: 07/05/2024] Open
Abstract
Proton circuits within biological membranes, the foundation of natural bioenergetic systems, are significantly influenced by the lipid compositions of different biological membranes. In this study, we investigate the influence of mixed lipid membrane composition on the proton transfer (PT) properties on the surface of the membrane. We track the excited-state PT (ESPT) process from a tethered probe to the membrane with timescales and length scales of PT relevant to bioenergetic systems. Two processes can happen during ESPT: the initial PT from the probe to the membrane at short timescales, followed by diffusion of dissociated protons around the probe on the membrane, and the possible geminate recombination with the probe at longer timescales. Here, we use membranes composed of mixtures of phosphatidylcholine (PC) and phosphatidic acid (PA). We show that the changes in the ESPT properties are not monotonous with the concentration of the lipid mixture; at a low concentration of PA in PC, we find that the membrane is a poor proton acceptor. Molecular dynamics simulations indicate that the membrane is more structured at this specific lipid mixture, with the least number of defects. Accordingly, we suggest that the structure of the membrane is an important factor in facilitating PT. We further show that the composition of the membrane affects the geminate proton diffusion around the probe, whereas, on a timescale of tens of nanoseconds, the dissociated proton is mostly lateral restricted to the membrane plane in PA membranes, while in PC, the diffusion is less restricted by the membrane.
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Affiliation(s)
| | - Mateusz Rzycki
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Anna Yucknovsky
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
| | | | - Dominik Drabik
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Nadav Amdursky
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel.
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2
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Fufina TY, Vasilieva LG. Role of hydrogen-bond networks on the donor side of photosynthetic reaction centers from purple bacteria. Biophys Rev 2023; 15:921-937. [PMID: 37974998 PMCID: PMC10643783 DOI: 10.1007/s12551-023-01109-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 08/01/2023] [Indexed: 11/19/2023] Open
Abstract
For the last decades, significant progress has been made in studying the biological functions of H-bond networks in membrane proteins, proton transporters, receptors, and photosynthetic reaction centers. Increasing availability of the X-ray crystal and cryo-electron microscopy structures of photosynthetic complexes resolved with high atomic resolution provides a platform for their comparative analysis. It allows identifying structural factors that are ensuring the high quantum yield of the photochemical reactions and are responsible for the stability of the membrane complexes. The H-bond networks are known to be responsible for proton transport associated with electron transfer from the primary to the secondary quinone as well as in the processes of water oxidation in photosystem II. Participation of such networks in reactions proceeding on the periplasmic side of bacterial photosynthetic reaction centers is less studied. This review summarizes the current understanding of the role of H-bond networks on the donor side of photosynthetic reaction centers from purple bacteria. It is discussed that the networks may be involved in providing close association with mobile electron carriers, in light-induced proton transport, in regulation of the redox properties of bacteriochlorophyll cofactors, and in stabilization of the membrane protein structure at the interface of membrane and soluble phases.
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Affiliation(s)
- T. Yu. Fufina
- Federal Research Center Pushchino Scientific Center for Biological Research, Institute of Basic Biological Problems, Russian Academy of Sciences, Institutskaya Str, 2, 142290 Pushchino, Russia
| | - L. G. Vasilieva
- Federal Research Center Pushchino Scientific Center for Biological Research, Institute of Basic Biological Problems, Russian Academy of Sciences, Institutskaya Str, 2, 142290 Pushchino, Russia
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3
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Vinutha AS, Rajasekaran R. Insight on the mechanism of hexameric Pseudin-4 against bacterial membrane-mimetic environment. J Comput Aided Mol Des 2023:10.1007/s10822-023-00516-2. [PMID: 37368161 DOI: 10.1007/s10822-023-00516-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 06/22/2023] [Indexed: 06/28/2023]
Abstract
As an alternative to antibiotics, Antimicrobial Peptides (AMPs) possess unique properties including cationic, amphipathic and their abundance in nature, but the exact characteristics of AMPs against bacterial membranes are still undetermined. To estimate the structural stability and functional activity of AMPs, the Pseudin AMPs (Pse-1, Pse-2, Pse-3, and Pse-4) from Hylid frog species, Pseudis paradoxa, an abundantly discovered source for AMPs were examined. We studied the intra-peptide interactions and thermal denaturation stability of peptides, as well as the geometrical parameters and secondary structure profiles of their conformational trajectories. On this basis, the peptides were screened out and the highly stable peptide, Pse-4 was subjected to membrane simulation in order to observe the changes in membrane curvature formed by Pse-4 insertion. Monomeric Pse-4 was found to initiate the membrane disruption; however, a stable multimeric form of Pse-4 might be competent to counterbalance the helix-coil transition and to resist the hydrophobic membrane environment. Eventually, hexameric Pse-4 on membrane simulation exhibited the hydrogen bond formation with E. coli bacterial membrane and thereby, leading to the formation of membrane spanning pore that allowed the entry of excess water molecules into the membrane shell, thus causing membrane deformation. Our report points out the mechanism of Pse-4 peptide against the bacterial membrane for the first time. Relatively, Pse-4 works on the barrel stave model against E. coli bacterial membrane; hence it might act as a good therapeutic scaffold in the treatment of multi-drug resistant bacterial strains.
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Affiliation(s)
- A S Vinutha
- Quantitative Biology Lab, Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology (VIT, Deemed to be University), Vellore, Tamil Nadu, India
| | - R Rajasekaran
- Quantitative Biology Lab, Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology (VIT, Deemed to be University), Vellore, Tamil Nadu, India.
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4
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White SH. Fifty Years of Biophysics at the Membrane Frontier. Annu Rev Biophys 2023; 52:21-67. [PMID: 36791747 DOI: 10.1146/annurev-biophys-051622-112341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
The author first describes his childhood in the South and the ways in which it fostered the values he has espoused throughout his life, his development of a keen fascination with science, and the influences that supported his progress toward higher education. His experiences in ROTC as a student, followed by two years in the US Army during the Vietnam War, honed his leadership skills. The bulk of the autobiography is a chronological journey through his scientific career, beginning with arrival at the University of California, Irvine in 1972, with an emphasis on the postdoctoral students and colleagues who have contributed substantially to each phase of his lab's progress. White's fundamental findings played a key role in the development of membrane biophysics, helping establish it as fertile ground for research. A story gradually unfolds that reveals the deeply collaborative and painstakingly executed work necessary for a successful career in science.
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Affiliation(s)
- Stephen H White
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA;
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5
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Cetin E, Atilgan AR, Atilgan C. DHFR Mutants Modulate Their Synchronized Dynamics with the Substrate by Shifting Hydrogen Bond Occupancies. J Chem Inf Model 2022; 62:6715-6726. [PMID: 35984987 PMCID: PMC9795552 DOI: 10.1021/acs.jcim.2c00507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Antibiotic resistance is a global health problem in which mutations occurring in functional proteins render drugs ineffective. The working mechanisms of the arising mutants are seldom apparent; a methodology to decipher these mechanisms systematically would render devising therapies to control the arising mutational pathways possible. Here we utilize Cα-Cβ bond vector relaxations obtained from moderate length MD trajectories to determine conduits for functionality of the resistance conferring mutants of Escherichia coli dihydrofolate reductase. We find that the whole enzyme is synchronized to the motions of the substrate, irrespective of the mutation introducing gain-of-function or loss-of function. The total coordination of the motions suggests changes in the hydrogen bond dynamics with respect to the wild type as a possible route to determine and classify the mode-of-action of individual mutants. As a result, nine trimethoprim-resistant point mutations arising frequently in evolution experiments are categorized. One group of mutants that display the largest occurrence (L28R, W30G) work directly by modifying the dihydrofolate binding region. Conversely, W30R works indirectly by the formation of the E139-R30 salt bridge which releases energy resulting from tight binding by distorting the binding cavity. A third group (D27E, F153S, I94L) arising as single, resistance invoking mutants in evolution experiment trajectories allosterically and dynamically affects a hydrogen bonding motif formed at residues 59-69-71 which in turn modifies the binding site dynamics. The final group (I5F, A26T, R98P) consists of those mutants that have properties most similar to the wild type; these only appear after one of the other mutants is fixed on the protein structure and therefore display clear epistasis. Thus, we show that the binding event is governed by the entire enzyme dynamics while the binding site residues play gating roles. The adjustments made in the total enzyme in response to point mutations are what make quantifying and pinpointing their effect a hard problem. Here, we show that hydrogen bond dynamics recorded on sub-μs time scales provide the necessary fingerprints to decipher the various mechanisms at play.
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6
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Colorado-Peralta R, María Rivera-Villanueva J, Manuel Mora-Hernández J, Morales-Morales D, Ángel Alfonso-Herrera L. An overview of the role of supramolecular interactions in gas storage using MOFs. Polyhedron 2022. [DOI: 10.1016/j.poly.2022.115995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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7
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Schoeman D, Cloete R, Fielding BC. The Flexible, Extended Coil of the PDZ-Binding Motif of the Three Deadly Human Coronavirus E Proteins Plays a Role in Pathogenicity. Viruses 2022; 14:v14081707. [PMID: 36016329 PMCID: PMC9416557 DOI: 10.3390/v14081707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/22/2022] [Accepted: 07/29/2022] [Indexed: 02/04/2023] Open
Abstract
The less virulent human (h) coronaviruses (CoVs) 229E, NL63, OC43, and HKU1 cause mild, self-limiting respiratory tract infections, while the more virulent SARS-CoV-1, MERS-CoV, and SARS-CoV-2 have caused severe outbreaks. The CoV envelope (E) protein, an important contributor to the pathogenesis of severe hCoV infections, may provide insight into this disparate severity of the disease. We, therefore, generated full-length E protein models for SARS-CoV-1 and -2, MERS-CoV, HCoV-229E, and HCoV-NL63 and docked C-terminal peptides of each model to the PDZ domain of the human PALS1 protein. The PDZ-binding motif (PBM) of the SARS-CoV-1 and -2 and MERS-CoV models adopted a more flexible, extended coil, while the HCoV-229E and HCoV-NL63 models adopted a less flexible alpha helix. All the E peptides docked to PALS1 occupied the same binding site and the more virulent hCoV E peptides generally interacted more stably with PALS1 than the less virulent ones. We hypothesize that the increased flexibility of the PBM in the more virulent hCoVs facilitates more stable binding to various host proteins, thereby contributing to more severe disease. This is the first paper to model full-length 3D structures for both the more virulent and less virulent hCoV E proteins, providing novel insights for possible drug and/or vaccine development.
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Affiliation(s)
- Dewald Schoeman
- Molecular Biology and Virology Research Laboratory, Department of Medical Biosciences, University of the Western Cape, Private Bag X17, Bellville, Cape Town 7535, South Africa;
| | - Ruben Cloete
- South African Medical Research Council Bioinformatics Unit, South African National Bioinformatics Institute, University of the Western Cape, Private Bag X17, Bellville, Cape Town 7535, South Africa;
| | - Burtram C. Fielding
- Molecular Biology and Virology Research Laboratory, Department of Medical Biosciences, University of the Western Cape, Private Bag X17, Bellville, Cape Town 7535, South Africa;
- Correspondence:
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8
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Matern J, Fernández Z, Bäumer N, Fernández G. Expanding the Scope of Metastable Species in Hydrogen Bonding-Directed Supramolecular Polymerization. Angew Chem Int Ed Engl 2022; 61:e202203783. [PMID: 35362184 PMCID: PMC9321731 DOI: 10.1002/anie.202203783] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Indexed: 12/23/2022]
Abstract
We reveal unique hydrogen (H-) bonding patterns and exploit them to control the kinetics, pathways and length of supramolecular polymers (SPs). New bisamide-containing monomers were designed to elucidate the role of competing intra- vs. intermolecular H-bonding interactions on the kinetics of supramolecular polymerization (SP). Remarkably, two polymerization-inactive metastable states were discovered. Contrary to previous examples, the commonly assumed intramolecularly H-bonded monomer does not evolve into intermolecularly H-bonded SPs via ring opening, but rather forms a metastable dimer. In this dimer, all H-bonding sites are saturated, either intra- or intermolecularly, hampering elongation. The dimers exhibit an advantageous preorganization, which upon opening of the intramolecular portion of the H-bonding motif facilitates SP in a consecutive process. The retardation of spontaneous self-assembly as a result of two metastable states enables length control in SP by seed-mediated growth.
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Affiliation(s)
- Jonas Matern
- Organisch-Chemisches InstitutWestfälische Wilhelms-Universität MünsterCorrensstraße 3648149MünsterGermany
| | - Zulema Fernández
- Organisch-Chemisches InstitutWestfälische Wilhelms-Universität MünsterCorrensstraße 3648149MünsterGermany
| | - Nils Bäumer
- Organisch-Chemisches InstitutWestfälische Wilhelms-Universität MünsterCorrensstraße 3648149MünsterGermany
| | - Gustavo Fernández
- Organisch-Chemisches InstitutWestfälische Wilhelms-Universität MünsterCorrensstraße 3648149MünsterGermany
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9
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Multiscale Dynamics of Lipid Vesicles in Polymeric Microenvironment. MEMBRANES 2022; 12:membranes12070640. [PMID: 35877843 PMCID: PMC9318666 DOI: 10.3390/membranes12070640] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/15/2022] [Accepted: 06/18/2022] [Indexed: 02/06/2023]
Abstract
Understanding dynamic and complex interaction of biological membranes with extracellular matrices plays a crucial role in controlling a variety of cell behavior and functions, from cell adhesion and growth to signaling and differentiation. Tremendous interest in tissue engineering has made it possible to design polymeric scaffolds mimicking the topology and mechanical properties of the native extracellular microenvironment; however, a fundamental question remains unanswered: that is, how the viscoelastic extracellular environment modifies the hierarchical dynamics of lipid membranes. In this work, we used aqueous solutions of poly(ethylene glycol) (PEG) with different molecular weights to mimic the viscous medium of cells and nearly monodisperse unilamellar DMPC/DMPG liposomes as a membrane model. Using small-angle X-ray scattering (SAXS), dynamic light scattering, temperature-modulated differential scanning calorimetry, bulk rheology, and fluorescence lifetime spectroscopy, we investigated the structural phase map and multiscale dynamics of the liposome–polymer mixtures. The results suggest an unprecedented dynamic coupling between polymer chains and phospholipid bilayers at different length/time scales. The microviscosity of the lipid bilayers is directly influenced by the relaxation of the whole chain, resulting in accelerated dynamics of lipids within the bilayers in the case of short chains compared to the polymer-free liposome case. At the macroscopic level, the gel-to-fluid transition of the bilayers results in a remarkable thermal-stiffening behavior of polymer–liposome solutions that can be modified by the concentration of the liposomes and the polymer chain length.
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10
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Bondar AN. Graphs of Hydrogen-Bond Networks to Dissect Protein Conformational Dynamics. J Phys Chem B 2022; 126:3973-3984. [PMID: 35639610 DOI: 10.1021/acs.jpcb.2c00200] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Dynamic hydrogen bonds and hydrogen-bond networks are ubiquitous in proteins and protein complexes. Functional roles that have been assigned to hydrogen-bond networks include structural plasticity for protein function, allosteric conformational coupling, long-distance proton transfers, and transient storage of protons. Advances in structural biology provide invaluable insights into architectures of large proteins and protein complexes of direct interest to human physiology and disease, including G Protein Coupled Receptors (GPCRs) and the SARS-Covid-19 spike protein S, and give rise to the challenge of how to identify those interactions that are more likely to govern protein dynamics. This Perspective discusses applications of graph-based algorithms to dissect dynamical hydrogen-bond networks of protein complexes, with illustrations for GPCRs and spike protein S. H-bond graphs provide an overview of sites in GPCR structures where hydrogen-bond dynamics would be required to assemble longer-distance networks between functionally important motifs. In the case of spike protein S, graphs identify regions of the protein where hydrogen bonds rearrange during the reaction cycle and where local hydrogen-bond networks likely change in a virus variant of concern.
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Affiliation(s)
- Ana-Nicoleta Bondar
- University of Bucharest, Faculty of Physics, Str. Atomiştilor 405, 077125 Bucharest-Măgurele, Romania.,Institute for Neuroscience and Medicine and Institute for Advanced Simulations (IAS-5/INM-9), Computational Biomedicine, Forschungszentrum Jülich, 52425 Jülich, Germany
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11
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Evaluation of antimicrobial activity and phytochemical qualitative analysis of Ephedra foliata Boiss. ex C.A. Mey. HERBA POLONICA 2022. [DOI: 10.2478/hepo-2022-0007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Summary
Introduction: Ephedra foliata Boiss. ex C.A. Mey of the Ephedraceae family is an evergreen shrub distributed throughout North Africa and Southwest Asia. It has been a characteristic source of alkaloids like ephedrine, pseudoephedrine and other related mixes, which are of great importance for their biological and pharmacological potential.
Objective: This study is aimed to evaluate the antimicrobial potential and phytochemical constituents studies on stem, leaves and flowers extracts of E. foliata.
Method: The air-dried plant sample was powdered with an electric grinder, then extracted successively with solvents, namely petroleum ether, petroleum benzene, ethyl acetate, methanol, and aqueous using Soxhlet apparatus for 72 hours. The solid matter was separated by filtration and then solvents were evaporated with a vacuum rotary evaporator to obtain the crude extracts. Freshly prepared crude extracts were subjected to the standard procedures of preliminary phytochemical screening for the investigation of the presence or absence of different phytoconstituents. The result showed the presence of reducing sugars, flavonoids, and cardiac glycosides. Antimicrobial activity of the crude extract was determined by agar well diffusion method.
Results: Ethyl acetate extract showed the highest antimicrobial activity against all the tested pathogens (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Yersinia enterocolitica, Streptococcus pneumonia, Aspergillus terreus, Cladosporium herbarum and Candida tropicalis). All five extracts inhibited the growth of Y. enterocolitica.
Conclusion: The antimicrobial properties of E. foliata extracts are of great interest in light of the ongoing threat of microbial resistance to conventional antibiotics. Phytoconstituents present in the E. foliata extracts might be a good alternative to modern antimicrobials as a natural compound.
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12
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Matern J, Fernandez Z, Bäumer N, Fernandez G. Expanding the Scope of Metastable Species in Hydrogen Bonding‐Directed Supramolecular Polymerization. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202203783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Jonas Matern
- WWU Münster: Westfalische Wilhelms-Universitat Munster Organisch-Chemisches Institut GERMANY
| | - Zulema Fernandez
- WWU Münster: Westfalische Wilhelms-Universitat Munster Organisch-Chemisches Institut GERMANY
| | - Nils Bäumer
- WWU Münster: Westfalische Wilhelms-Universitat Munster Organisch-Chemisches Institut GERMANY
| | - Gustavo Fernandez
- WWU Münster Organisch-Chemisches Institut Correnstraße, 4ß 48149 Münster GERMANY
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13
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Bondar AN. Mechanisms of long-distance allosteric couplings in proton-binding membrane transporters. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 128:199-239. [PMID: 35034719 DOI: 10.1016/bs.apcsb.2021.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Membrane transporters that use proton binding and proton transfer for function couple local protonation change with changes in protein conformation and water dynamics. Changes of protein conformation might be required to allow transient formation of hydrogen-bond networks that bridge proton donor and acceptor pairs separated by long distances. Inter-helical hydrogen-bond networks adjust rapidly to protonation change, and ensure rapid response of the protein structure and dynamics. Membrane transporters with known three-dimensional structures and proton-binding groups inform on general principles of protonation-coupled protein conformational dynamics. Inter-helical hydrogen bond motifs between proton-binding carboxylate groups and a polar sidechain are observed in unrelated membrane transporters, suggesting common principles of coupling protonation change with protein conformational dynamics.
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Affiliation(s)
- Ana-Nicoleta Bondar
- University of Bucharest, Faculty of Physics, Măgurele, Romania; Forschungszentrum Jülich, Institute of Computational Biomedicine, Jülich, Germany.
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14
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Bertalan É, Lesca E, Schertler GFX, Bondar AN. C-Graphs Tool with Graphical User Interface to Dissect Conserved Hydrogen-Bond Networks: Applications to Visual Rhodopsins. J Chem Inf Model 2021; 61:5692-5707. [PMID: 34670076 DOI: 10.1021/acs.jcim.1c00827] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Dynamic hydrogen-bond networks provide proteins with structural plasticity required to translate signals such as ligand binding into a cellular response or to transport ions and larger solutes across membranes and, thus, are of central interest to understand protein reaction mechanisms. Here, we present C-Graphs, an efficient tool with graphical user interface that analyzes data sets of static protein structures or of independent numerical simulations to identify conserved, vs unique, hydrogen bonds and hydrogen-bond networks. For static structures, which may belong to the same protein or to proteins with different sequences, C-Graphs uses a clustering algorithm to identify sites of the hydrogen-bond network where waters are conserved among the structures. Using C-Graphs, we identify an internal protein-water hydrogen-bond network common to static structures of visual rhodopsins and adenosine A2A G protein-coupled receptors (GPCRs). Molecular dynamics simulations of a visual rhodopsin indicate that the conserved hydrogen-bond network from static structure can recruit dynamic hydrogen bonds and extend throughout most of the receptor. We release with this work the code for C-Graphs and its graphical user interface.
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Affiliation(s)
- Éva Bertalan
- Theoretical Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - Elena Lesca
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, ETH Zürich, 5303 Villigen-PSI, Switzerland.,Department of Biology, ETH Zürich, 8093 Zürich, Switzerland
| | - Gebhard F X Schertler
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, ETH Zürich, 5303 Villigen-PSI, Switzerland.,Department of Biology, ETH Zürich, 8093 Zürich, Switzerland
| | - Ana-Nicoleta Bondar
- Theoretical Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany.,Faculty of Physics, University of Bucharest, Strada Atomiştilor Nr. 405, Măgurele 077125, Romania.,Computational Biomedicine, IAS-5/INM-9, Institute for Neuroscience and Medicine and Institute for Advanced Simulations, Forschungszentrum Jülich, 52425 Jülich, Germany
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15
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Smułek W, Siejak P, Fathordoobady F, Masewicz Ł, Guo Y, Jarzębska M, Kitts DD, Kowalczewski PŁ, Baranowska HM, Stangierski J, Szwajca A, Pratap-Singh A, Jarzębski M. Whey Proteins as a Potential Co-Surfactant with Aesculus hippocastanum L. as a Stabilizer in Nanoemulsions Derived from Hempseed Oil. Molecules 2021; 26:molecules26195856. [PMID: 34641403 PMCID: PMC8510466 DOI: 10.3390/molecules26195856] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 09/07/2021] [Accepted: 09/20/2021] [Indexed: 12/19/2022] Open
Abstract
The use of natural surfactants including plant extracts, plant hydrocolloids and proteins in nanoemulsion systems has received commercial interest due to demonstrated safety of use and potential health benefits of plant products. In this study, a whey protein isolate (WPI) from a byproduct of cheese production was used to stabilize a nanoemulsion formulation that contained hempseed oil and the Aesculus hippocastanum L. extract (AHE). A Box-Behnken experimental design was used to set the formulation criteria and the optimal nanoemulsion conditions, used subsequently in follow-up experiments that measured specifically emulsion droplet size distribution, stability tests and visual quality. Regression analysis showed that the concentration of HSO and the interaction between HSO and the WPI were the most significant factors affecting the emulsion polydispersity index and droplet size (nm) (p < 0.05). Rheological tests, Fourier transform infrared spectroscopy (FTIR) analysis and L*a*b* color parameters were also taken to characterize the physicochemical properties of the emulsions. Emulsion systems with a higher concentration of the AHE had a potential metabolic activity up to 84% in a microbiological assay. It can be concluded from our results that the nanoemulsion system described herein is a safe and stable formulation with potential biological activity and health benefits that complement its use in the food industry.
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Affiliation(s)
- Wojciech Smułek
- Institute of Chemical Technology and Engineering, Poznan University of Technology, Berdychowo 4, 60-695 Poznań, Poland;
| | - Przemysław Siejak
- Department of Physics and Biophysics, Faculty of Food Science and Nutrition, Poznań University of Life Sciences, Wojska Polskiego 38/42, 60-637 Poznań, Poland; (P.S.); (Ł.M.); (H.M.B.)
| | - Farahnaz Fathordoobady
- Food, Nutrition and Health Program, Faculty of Land & Food Systems, The University of British Columbia, 2205 East Mall, Vancouver, BC V6T 1Z4, Canada; (F.F.); (Y.G.); (D.D.K.)
| | - Łukasz Masewicz
- Department of Physics and Biophysics, Faculty of Food Science and Nutrition, Poznań University of Life Sciences, Wojska Polskiego 38/42, 60-637 Poznań, Poland; (P.S.); (Ł.M.); (H.M.B.)
| | - Yigong Guo
- Food, Nutrition and Health Program, Faculty of Land & Food Systems, The University of British Columbia, 2205 East Mall, Vancouver, BC V6T 1Z4, Canada; (F.F.); (Y.G.); (D.D.K.)
| | | | - David D. Kitts
- Food, Nutrition and Health Program, Faculty of Land & Food Systems, The University of British Columbia, 2205 East Mall, Vancouver, BC V6T 1Z4, Canada; (F.F.); (Y.G.); (D.D.K.)
| | - Przemysław Łukasz Kowalczewski
- Department of Food Technology of Plant Origin, Poznań University of Life Sciences, 31 Wojska Polskiego St., 60-624 Poznań, Poland;
| | - Hanna Maria Baranowska
- Department of Physics and Biophysics, Faculty of Food Science and Nutrition, Poznań University of Life Sciences, Wojska Polskiego 38/42, 60-637 Poznań, Poland; (P.S.); (Ł.M.); (H.M.B.)
| | - Jerzy Stangierski
- Department of Food Quality and Safety Management, Faculty of Food Science and Nutrition, Poznań University of Life Sciences, Wojska Polskiego 31/33, 60-624 Poznań, Poland;
| | - Anna Szwajca
- Department of Synthesis and Structure of Organic Compounds, Faculty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland;
| | - Anubhav Pratap-Singh
- Food, Nutrition and Health Program, Faculty of Land & Food Systems, The University of British Columbia, 2205 East Mall, Vancouver, BC V6T 1Z4, Canada; (F.F.); (Y.G.); (D.D.K.)
- Correspondence: (A.P.-S.); (M.J.)
| | - Maciej Jarzębski
- Department of Physics and Biophysics, Faculty of Food Science and Nutrition, Poznań University of Life Sciences, Wojska Polskiego 38/42, 60-637 Poznań, Poland; (P.S.); (Ł.M.); (H.M.B.)
- Correspondence: (A.P.-S.); (M.J.)
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16
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Siemers M, Bondar AN. Interactive Interface for Graph-Based Analyses of Dynamic H-Bond Networks: Application to Spike Protein S. J Chem Inf Model 2021; 61:2998-3014. [PMID: 34133162 DOI: 10.1021/acs.jcim.1c00306] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Dynamic hydrogen-bond networks are key determinants of protein conformational dynamics. In the case of macromolecular protein complexes, which can have a large number of hydrogen bonds giving rise to extensive hydrogen-bond networks, efficient algorithms are required to analyze interactions that could be important for the dynamics and biological function of the complex. We present here a highly efficient, standalone interface designed for analyses of dynamical hydrogen-bond networks of biomolecules and macromolecular complexes. To facilitate a comprehensive description of protein dynamics, the interface includes analyses of hydrophobic interactions. We illustrate the usefulness and workflow of the interface by dissecting the dynamics of the ectodomain of SARS-CoV-2 protein S in its closed conformation. We find that protein S contains numerous local clusters of dynamic hydrogen bonds and identify hydrogen bonds that are sampled persistently. The receptor binding domain of the spike protein hosts only a handful of persistent hydrogen-bond clusters, suggesting structural plasticity. Our data analysis interface is released here for open use.
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Affiliation(s)
- Malte Siemers
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics, Arnimallee 14, D-14195 Berlin, Germany
| | - Ana-Nicoleta Bondar
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics, Arnimallee 14, D-14195 Berlin, Germany
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17
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Liscano Y, Medina L, Oñate-Garzón J, Gúzman F, Pickholz M, Delgado JP. In Silico Selection and Evaluation of Pugnins with Antibacterial and Anticancer Activity Using Skin Transcriptome of Treefrog ( Boana pugnax). Pharmaceutics 2021; 13:578. [PMID: 33919639 PMCID: PMC8074116 DOI: 10.3390/pharmaceutics13040578] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 04/10/2021] [Accepted: 04/10/2021] [Indexed: 12/14/2022] Open
Abstract
In order to combat bacterial and cancer resistance, we identified peptides (pugnins) with dual antibacterial l-anticancer activity from the Boana pugnax (B. pugnax) skin transcriptome through in silico analysis. Pugnins A and B were selected owing to their high similarity to the DS4.3 peptide, which served as a template for their alignment to the B. pugnax transcriptome, as well as their function as part of a voltage-dependent potassium channel protein. The secondary peptide structure stability in aqueous medium was evaluated as well, and after interaction with the Escherichia coli (E. coli) membrane model using molecular dynamics. These pugnins were synthesized via solid-phase synthesis strategy and verified by Reverse phase high-performance liquid chromatography (RP-HPLC) and mass spectrometry. Subsequently, their alpha-helix structure was determined by circular dichroism, after which antibacterial tests were then performed to evaluate their antimicrobial activity. Cytotoxicity tests against cancer cells also showed selectivity of pugnin A toward breast cancer (MFC7) cells, and pugnin B toward prostate cancer (PC3) cells. Alternatively, flow cytometry revealed necrotic cell damage with a major cytotoxic effect on human keratinocytes (HaCaT) control cells. Therefore, the pugnins found in the transcriptome of B. pugnax present dual antibacterial-anticancer activity with reduced selectivity to normal eukaryotic cells.
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Affiliation(s)
- Yamil Liscano
- Grupo de Investigación en Química y Biotecnología (QUIBIO), Facultad de Ciencias Básicas, Universidad Santiago de Cali, Calle 5 N° 62-00, Cali 760035, Colombia;
- Grupo Genética, Regeneración y Cáncer, Facultad de Ciencias Exactas y Naturales, Instituto de Biología, Universidad de Antioquia, Medellín 050010, Colombia;
| | - Laura Medina
- Grupo Genética, Regeneración y Cáncer, Facultad de Ciencias Exactas y Naturales, Instituto de Biología, Universidad de Antioquia, Medellín 050010, Colombia;
| | - Jose Oñate-Garzón
- Grupo de Investigación en Química y Biotecnología (QUIBIO), Facultad de Ciencias Básicas, Universidad Santiago de Cali, Calle 5 N° 62-00, Cali 760035, Colombia;
| | - Fanny Gúzman
- Núcleo de Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, 2374631 Av. Universidad, Curauma 330, Chile;
| | - Monica Pickholz
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA, CONICET-UBA, Ciudad Universitaria, Pabellón 1, Buenos Aires 1428, Argentina;
| | - Jean Paul Delgado
- Grupo Genética, Regeneración y Cáncer, Facultad de Ciencias Exactas y Naturales, Instituto de Biología, Universidad de Antioquia, Medellín 050010, Colombia;
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18
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Phosphatidylglyerol Lipid Binding at the Active Site of an Intramembrane Protease. J Membr Biol 2020; 253:563-576. [PMID: 33210155 PMCID: PMC7688093 DOI: 10.1007/s00232-020-00152-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 11/04/2020] [Indexed: 10/25/2022]
Abstract
Transmembrane substrate cleavage by the small Escherichia coli rhomboid protease GlpG informs on mechanisms by which lipid interactions shape reaction coordinates of membrane-embedded enzymes. Here, I review and discuss new work on the molecular picture of protein-lipid interactions that might govern the formation of the substrate-enzyme complex in fluid lipid membranes. Negatively charged PG-type lipids are of particular interest, because they are a major component of bacterial membranes. Atomistic computer simulations indicate POPG and DOPG lipids bridge remote parts of GlpG and might pre-occupy the substrate-docking site. Inhibition of catalytic activity by PG lipids could arise from ligand-like lipid binding at the active site, which could delay or prevent substrate docking. Dynamic protein-lipid H-bond networks, water access to the active site, and fluctuations in the orientation of GlpG suggest that GlpG has lipid-coupled dynamics that could shape the energy landscape of transmembrane substrate docking.
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19
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Karathanou K, Lazaratos M, Bertalan É, Siemers M, Buzar K, Schertler GFX, Del Val C, Bondar AN. A graph-based approach identifies dynamic H-bond communication networks in spike protein S of SARS-CoV-2. J Struct Biol 2020; 212:107617. [PMID: 32919067 PMCID: PMC7481144 DOI: 10.1016/j.jsb.2020.107617] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 09/03/2020] [Accepted: 09/06/2020] [Indexed: 02/07/2023]
Abstract
Corona virus spike protein S is a large homo-trimeric protein anchored in the membrane of the virion particle. Protein S binds to angiotensin-converting-enzyme 2, ACE2, of the host cell, followed by proteolysis of the spike protein, drastic protein conformational change with exposure of the fusion peptide of the virus, and entry of the virion into the host cell. The structural elements that govern conformational plasticity of the spike protein are largely unknown. Here, we present a methodology that relies upon graph and centrality analyses, augmented by bioinformatics, to identify and characterize large H-bond clusters in protein structures. We apply this methodology to protein S ectodomain and find that, in the closed conformation, the three protomers of protein S bring the same contribution to an extensive central network of H-bonds, and contribute symmetrically to a relatively large H-bond cluster at the receptor binding domain, and to a cluster near a protease cleavage site. Markedly different H-bonding at these three clusters in open and pre-fusion conformations suggest dynamic H-bond clusters could facilitate structural plasticity and selection of a protein S protomer for binding to the host receptor, and proteolytic cleavage. From analyses of spike protein sequences we identify patches of histidine and carboxylate groups that could be involved in transient proton binding.
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Affiliation(s)
- Konstantina Karathanou
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics, Arnimallee 14, D-14195 Berlin, Germany
| | - Michalis Lazaratos
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics, Arnimallee 14, D-14195 Berlin, Germany
| | - Éva Bertalan
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics, Arnimallee 14, D-14195 Berlin, Germany
| | - Malte Siemers
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics, Arnimallee 14, D-14195 Berlin, Germany
| | - Krzysztof Buzar
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics, Arnimallee 14, D-14195 Berlin, Germany
| | - Gebhard F X Schertler
- Paul Scherrer Institut, Department of Biology and Chemistry, Laboratory of Biomolecular Research, CH-5303 Villigen-PSI, Switzerland; ETH Zürich, Department of Biology, 8093 Zürich, Switzerland
| | - Coral Del Val
- University of Granada, Department of Computer Science and Artificial Intelligence, E-18071 Granada, Spain; Instituto de Investigación Biosanitaria ibs.GRANADA, 18012 Granada, Spain; Andalusian Research Institute in Data Science and Computational Intelligence (DaSCI Institute), 18014 Granada, Spain
| | - Ana-Nicoleta Bondar
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics, Arnimallee 14, D-14195 Berlin, Germany.
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20
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Letter to the Editor: Distanced Inspiration from the Career of Stephen H. White. J Membr Biol 2020; 254:1-3. [PMID: 33097980 DOI: 10.1007/s00232-020-00146-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 10/10/2020] [Indexed: 10/23/2022]
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21
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Lazaratos M, Karathanou K, Bondar AN. Graphs of dynamic H-bond networks: from model proteins to protein complexes in cell signaling. Curr Opin Struct Biol 2020; 64:79-87. [DOI: 10.1016/j.sbi.2020.06.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 05/28/2020] [Accepted: 06/08/2020] [Indexed: 12/13/2022]
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22
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Dehury B, Kepp KP. Membrane dynamics of γ-secretase with the anterior pharynx-defective 1B subunit. J Cell Biochem 2020; 122:69-85. [PMID: 32830360 DOI: 10.1002/jcb.29832] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 07/13/2020] [Indexed: 01/12/2023]
Abstract
The four-subunit protease complex γ-secretase cleaves many single-pass transmembrane (TM) substrates, including Notch and β-amyloid precursor protein to generate amyloid-β (Aβ), central to Alzheimer's disease. Two of the subunits anterior pharynx-defective 1 (APH-1) and presenilin (PS) exist in two homologous forms APH1-A and APH1-B, and PS1 and PS2. The consequences of these variations are poorly understood and could affect Aβ production and γ-secretase medicine. Here, we developed the first complete structural model of the APH-1B subunit using the published cryo-electron microscopy (cryo-EM) structures of APH1-A (Protein Data Bank: 5FN2, 5A63, and 6IYC). We then performed all-atom molecular dynamics simulations at 303 K in a realistic bilayer system to understand both APH-1B alone and in γ-secretase without and with substrate C83-bound. We show that APH-1B adopts a 7TM topology with a water channel topology similar to APH-1A. We demonstrate direct transport of water through this channel, mainly via Glu84, Arg87, His170, and His196. The apo and holo states closely resemble the experimental cryo-EM structures with APH-1A, however with subtle differences: The substrate-bound APH-1B γ-secretase was quite stable, but some TM helices of PS1 and APH-1B rearranged in the membrane consistent with the disorder seen in the cryo-EM data. This produces different accessibility of water molecules for the catalytic aspartates of PS1, critical for Aβ production. In particular, we find that the typical distance between the catalytic aspartates of PS1 and the C83 cleavage sites are shorter in APH-1B, that is, it represents a more closed state, due to interactions with the C-terminal fragment of PS1. Our structural-dynamic model of APH-1B alone and in γ-secretase suggests generally similar topology but some notable differences in water accessibility which may be relevant to the protein's existence in two forms and their specific function and location.
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Affiliation(s)
- Budheswar Dehury
- DTU Chemistry, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Kasper P Kepp
- DTU Chemistry, Technical University of Denmark, Kongens Lyngby, Denmark
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23
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Holt GT, Jou JD, Gill NP, Lowegard AU, Martin JW, Madden DR, Donald BR. Computational Analysis of Energy Landscapes Reveals Dynamic Features That Contribute to Binding of Inhibitors to CFTR-Associated Ligand. J Phys Chem B 2019; 123:10441-10455. [PMID: 31697075 DOI: 10.1021/acs.jpcb.9b07278] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The CFTR-associated ligand PDZ domain (CALP) binds to the cystic fibrosis transmembrane conductance regulator (CFTR) and mediates lysosomal degradation of mature CFTR. Inhibition of this interaction has been explored as a therapeutic avenue for cystic fibrosis. Previously, we reported the ensemble-based computational design of a novel peptide inhibitor of CALP, which resulted in the most binding-efficient inhibitor to date. This inhibitor, kCAL01, was designed using osprey and evinced significant biological activity in in vitro cell-based assays. Here, we report a crystal structure of kCAL01 bound to CALP and compare structural features against iCAL36, a previously developed inhibitor of CALP. We compute side-chain energy landscapes for each structure to not only enable approximation of binding thermodynamics but also reveal ensemble features that contribute to the comparatively efficient binding of kCAL01. Finally, we compare the previously reported design ensemble for kCAL01 vs the new crystal structure and show that, despite small differences between the design model and crystal structure, significant biophysical features that enhance inhibitor binding are captured in the design ensemble. This suggests not only that ensemble-based design captured thermodynamically significant features observed in vitro, but also that a design eschewing ensembles would miss the kCAL01 sequence entirely.
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Affiliation(s)
- Graham T Holt
- Department of Computer Science , Duke University , Durham , North Carolina 27708 , United States.,Program in Computational Biology and Bioinformatics , Duke University , Durham , North Carolina 27708 , United States
| | - Jonathan D Jou
- Department of Computer Science , Duke University , Durham , North Carolina 27708 , United States
| | - Nicholas P Gill
- Department of Biochemistry & Cell Biology , Geisel School of Medicine at Dartmouth , Hanover , New Hampshire 03755 , United States
| | - Anna U Lowegard
- Department of Computer Science , Duke University , Durham , North Carolina 27708 , United States.,Program in Computational Biology and Bioinformatics , Duke University , Durham , North Carolina 27708 , United States
| | - Jeffrey W Martin
- Department of Computer Science , Duke University , Durham , North Carolina 27708 , United States
| | - Dean R Madden
- Department of Biochemistry & Cell Biology , Geisel School of Medicine at Dartmouth , Hanover , New Hampshire 03755 , United States
| | - Bruce R Donald
- Department of Computer Science , Duke University , Durham , North Carolina 27708 , United States.,Department of Biochemistry , Duke University , Durham , North Carolina 27710 , United States.,Department of Chemistry , Duke University , Durham , North Carolina 27710 , United States
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24
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Liscano Y, Salamanca CH, Vargas L, Cantor S, Laverde-Rojas V, Oñate-Garzón J. Increases in Hydrophilicity and Charge on the Polar Face of Alyteserin 1c Helix Change its Selectivity towards Gram-Positive Bacteria. Antibiotics (Basel) 2019; 8:E238. [PMID: 31783657 PMCID: PMC6963856 DOI: 10.3390/antibiotics8040238] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 11/20/2019] [Accepted: 11/25/2019] [Indexed: 11/16/2022] Open
Abstract
Recently, resistance of pathogens towards conventional antibiotics has increased, representing a threat to public health globally. As part of the fight against this, studies on alternative antibiotics such as antimicrobial peptides have been performed, and it has been shown that their sequence and structure are closely related to their antimicrobial activity. Against this background, we here evaluated the antibacterial activity of two peptides developed by solid-phase synthesis, Alyteserin 1c (WT) and its mutant derivative (ΔM), which shows increased net charge and reduced hydrophobicity. These structural characteristics were modified as a result of amino acid substitutions on the polar face of the WT helix. The minimum inhibitory concentration (MIC) of both peptides was obtained in Gram-positive and Gram-negative bacteria. The results showed that the rational substitutions of the amino acids increased the activity in Gram-positive bacteria, especially against Staphylococcus aureus, for which the MIC was one-third of that for the WT analog. In contrast to the case for Gram-positive bacteria, these substitutions decreased activity against Gram-negative bacteria, especially in Escherichia coli, for which the MIC was eight-fold higher than that exhibited by the WT peptide. To understand this, models of the peptide behavior upon interacting with membranes of E. coli and S. aureus created using molecular dynamics were studied and it was determined that the helical stability of the peptide is indispensable for antimicrobial activity. The hydrogen bonds between the His20 of the peptides and the phospholipids of the membranes should modulate the selectivity associated with structural stability at the carboxy-terminal region of the peptides.
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Affiliation(s)
- Yamil Liscano
- Grupo de Génetica, Regeneración y Cáncer, Instituto de Química, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia, A.A., Medellín 1226, Colombia;
| | - Constain H. Salamanca
- Laboratorio de Diseño y Formulación de Productos Químicos y Derivados, Departamento de Ciencias Farmacéuticas, Facultad de Ciencias Naturales, Universidad Icesi, Cali 760035, Colombia;
| | - Lina Vargas
- Grupo de Investigación en Química y Biotecnología (QUIBIO), Facultad de Ciencias Básicas, Universidad Santiago de Cali, Calle 5 No. 62-00, Cali 760035, Colombia; (L.V.); (S.C.); (V.L.-R.)
| | - Stefania Cantor
- Grupo de Investigación en Química y Biotecnología (QUIBIO), Facultad de Ciencias Básicas, Universidad Santiago de Cali, Calle 5 No. 62-00, Cali 760035, Colombia; (L.V.); (S.C.); (V.L.-R.)
| | - Valentina Laverde-Rojas
- Grupo de Investigación en Química y Biotecnología (QUIBIO), Facultad de Ciencias Básicas, Universidad Santiago de Cali, Calle 5 No. 62-00, Cali 760035, Colombia; (L.V.); (S.C.); (V.L.-R.)
| | - José Oñate-Garzón
- Grupo de Investigación en Química y Biotecnología (QUIBIO), Facultad de Ciencias Básicas, Universidad Santiago de Cali, Calle 5 No. 62-00, Cali 760035, Colombia; (L.V.); (S.C.); (V.L.-R.)
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25
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Siemers M, Lazaratos M, Karathanou K, Guerra F, Brown LS, Bondar AN. Bridge: A Graph-Based Algorithm to Analyze Dynamic H-Bond Networks in Membrane Proteins. J Chem Theory Comput 2019; 15:6781-6798. [DOI: 10.1021/acs.jctc.9b00697] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Malte Siemers
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics, Arnimallee 14, D14195 Berlin, Germany
| | - Michalis Lazaratos
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics, Arnimallee 14, D14195 Berlin, Germany
| | - Konstantina Karathanou
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics, Arnimallee 14, D14195 Berlin, Germany
| | - Federico Guerra
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics, Arnimallee 14, D14195 Berlin, Germany
| | - Leonid S. Brown
- Department of Physics and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada
| | - Ana-Nicoleta Bondar
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics, Arnimallee 14, D14195 Berlin, Germany
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26
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Mihailescu M, Sorci M, Seckute J, Silin VI, Hammer J, Perrin BS, Hernandez JI, Smajic N, Shrestha A, Bogardus KA, Greenwood AI, Fu R, Blazyk J, Pastor RW, Nicholson LK, Belfort G, Cotten ML. Structure and Function in Antimicrobial Piscidins: Histidine Position, Directionality of Membrane Insertion, and pH-Dependent Permeabilization. J Am Chem Soc 2019; 141:9837-9853. [PMID: 31144503 DOI: 10.1021/jacs.9b00440] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Piscidins are histidine-enriched antimicrobial peptides that interact with lipid bilayers as amphipathic α-helices. Their activity at acidic and basic pH in vivo makes them promising templates for biomedical applications. This study focuses on p1 and p3, both 22-residue-long piscidins with 68% sequence identity. They share three histidines (H3, H4, and H11), but p1, which is significantly more permeabilizing, has a fourth histidine (H17). This study investigates how variations in amphipathic character associated with histidines affect the permeabilization properties of p1 and p3. First, we show that the permeabilization ability of p3, but not p1, is strongly inhibited at pH 6.0 when the conserved histidines are partially charged and H17 is predominantly neutral. Second, our neutron diffraction measurements performed at low water content and neutral pH indicate that the average conformation of p1 is highly tilted, with its C-terminus extending into the opposite leaflet. In contrast, p3 is surface bound with its N-terminal end tilted toward the bilayer interior. The deeper membrane insertion of p1 correlates with its behavior at full hydration: an enhanced ability to tilt, bury its histidines and C-terminus, induce membrane thinning and defects, and alter membrane conductance and viscoelastic properties. Furthermore, its pH-resiliency relates to the neutral state favored by H17. Overall, these results provide mechanistic insights into how differences in the histidine content and amphipathicity of peptides can elicit different directionality of membrane insertion and pH-dependent permeabilization. This work features complementary methods, including dye leakage assays, NMR-monitored titrations, X-ray and neutron diffraction, oriented CD, molecular dynamics, electrochemical impedance spectroscopy, surface plasmon resonance, and quartz crystal microbalance with dissipation.
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Affiliation(s)
- Mihaela Mihailescu
- Institute for Bioscience and Biotechnology Research , University of Maryland , Rockville , Maryland 20850 , United States
| | - Mirco Sorci
- Department of Chemical and Biological Engineering and Center for Biotechnology and Interdisciplinary Studies , Rensselaer Polytechnic Institute , Troy , New York 12180 , United States
| | - Jolita Seckute
- Department of Molecular Biology and Genetics , Cornell University , Ithaca , New York 14853 , United States
| | - Vitalii I Silin
- Institute for Bioscience and Biotechnology Research , University of Maryland , Rockville , Maryland 20850 , United States
| | - Janet Hammer
- Department of Biomedical Sciences , Ohio University , Athens , Ohio 45701 , United States
| | - B Scott Perrin
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute , National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Jorge I Hernandez
- Department of Bioengineering , Clemson University , Clemson , South Carolina 29634 , United States
| | - Nedzada Smajic
- Department of Chemistry , Hamilton College , Clinton , New York 13323 , United States
| | - Akritee Shrestha
- Department of Chemistry , Hamilton College , Clinton , New York 13323 , United States
| | - Kimberly A Bogardus
- Department of Chemistry , Hamilton College , Clinton , New York 13323 , United States
| | - Alexander I Greenwood
- Department of Applied Science , College of William and Mary , Williamsburg , Virginia 23185 , United States
| | - Riqiang Fu
- National High Magnetic Field Laboratory , Tallahassee , Florida 32310 , United States
| | - Jack Blazyk
- Department of Biomedical Sciences , Ohio University , Athens , Ohio 45701 , United States
| | - Richard W Pastor
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute , National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Linda K Nicholson
- Department of Molecular Biology and Genetics , Cornell University , Ithaca , New York 14853 , United States
| | - Georges Belfort
- Department of Chemical and Biological Engineering and Center for Biotechnology and Interdisciplinary Studies , Rensselaer Polytechnic Institute , Troy , New York 12180 , United States
| | - Myriam L Cotten
- Department of Applied Science , College of William and Mary , Williamsburg , Virginia 23185 , United States
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27
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Bondar AN. Mechanisms by Which Lipids Influence Conformational Dynamics of the GlpG Intramembrane Protease. J Phys Chem B 2019; 123:4159-4172. [PMID: 31059259 DOI: 10.1021/acs.jpcb.8b11291] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Rhomboid intramembrane proteases are bound to lipid membranes, where they dock and cleave other transmembrane substrates. How the lipid membrane surrounding the protease impacts the conformational dynamics of the protease is essential to understand because it informs on the reaction coordinate of substrate binding. Atomistic molecular dynamics simulations allow us to probe protein motions and characterize the coupling between protein and lipids. Simulations performed here on GlpG, the rhomboid protease from Escherichia coli, indicate that the thickness of the lipid membrane close to GlpG depends on both the composition of the lipid membrane and the conformation of GlpG. Transient binding of a lipid headgroup at the active site of the protease, as observed in some of the simulations reported here, suggests that a lipid headgroup might compete with the substrate for access to the GlpG active site. Interactions identified between lipid headgroups and the protein influence the dynamics of lipid interactions close to the substrate-binding site. These observations suggest that the lipid membrane environment shapes the energy profile of the substrate-docking region of the enzyme reaction coordinate.
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Affiliation(s)
- Ana-Nicoleta Bondar
- Freie Universität Berlin , Department of Physics, Theoretical Molecular Biophysics Group , Arnimallee 14 , D-14195 Berlin , Germany
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28
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Abstract
Membranes surrounding the biological cell and its internal compartments host proteins that catalyze chemical reactions essential for the functioning of the cell. Rather than being a passive structural matrix that holds membrane-embedded proteins in place, the membrane can largely shape the conformational energy landscape of membrane proteins and impact the energetics of their chemical reaction. Here, we highlight the challenges in understanding how lipids impact the conformational energy landscape of macromolecular membrane complexes whose functioning involves chemical reactions including proton transfer. We review here advances in our understanding of how chemical reactions occur at membrane interfaces gleaned with both theoretical and experimental advances using simple protein systems as guides. Our perspective is that of bridging experiments with theory to understand general physicochemical principles of membrane reactions, with a long term goal of furthering our understanding of the role of the lipids on the functioning of complex macromolecular assemblies at the membrane interface.
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Affiliation(s)
- Ana-Nicoleta Bondar
- Freie Universität Berlin , Department of Physics, Theoretical Molecular Biophysics Group , Arnimallee 14 , D-14195 Berlin , Germany
| | - M Joanne Lemieux
- University of Alberta , Department of Biochemistry, Membrane Protein Disease Research Group , Edmonton , Alberta T6G 2H7 , Canada
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Schöppe J, Ehrenmann J, Klenk C, Rucktooa P, Schütz M, Doré AS, Plückthun A. Crystal structures of the human neurokinin 1 receptor in complex with clinically used antagonists. Nat Commun 2019; 10:17. [PMID: 30604743 PMCID: PMC6318301 DOI: 10.1038/s41467-018-07939-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/03/2018] [Indexed: 12/28/2022] Open
Abstract
Neurokinins (or tachykinins) are peptides that modulate a wide variety of human physiology through the neurokinin G protein-coupled receptor family, implicated in a diverse array of pathological processes. Here we report high-resolution crystal structures of the human NK1 receptor (NK1R) bound to two small-molecule antagonist therapeutics – aprepitant and netupitant and the progenitor antagonist CP-99,994. The structures reveal the detailed interactions between clinically approved antagonists and NK1R, which induce a distinct receptor conformation resulting in an interhelical hydrogen-bond network that cross-links the extracellular ends of helices V and VI. Furthermore, the high-resolution details of NK1R bound to netupitant establish a structural rationale for the lack of basal activity in NK1R. Taken together, these co-structures provide a comprehensive structural basis of NK1R antagonism and will facilitate the design of new therapeutics targeting the neurokinin receptor family. Neurokinin receptors are G protein-coupled receptors. Here the authors present three crystal structures of the neurokinin 1 receptor (NK1R) in complex with small-molecule antagonists including aprepitant and netupitant and observe that these clinically approved compounds induce a conformational change in the receptor.
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Affiliation(s)
- Jendrik Schöppe
- Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Janosch Ehrenmann
- Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Christoph Klenk
- Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Prakash Rucktooa
- Sosei Heptares, Steinmetz Building, Granta Park, Great Abington, Cambridge, CB21 6DG, UK
| | - Marco Schütz
- Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.,Heptares Therapeutics Zürich AG, Grabenstrasse 11a, 8952, Zürich, Switzerland
| | - Andrew S Doré
- Sosei Heptares, Steinmetz Building, Granta Park, Great Abington, Cambridge, CB21 6DG, UK
| | - Andreas Plückthun
- Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.
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Shear-thickening behavior of gelatinized waxy starch dispersions promoted by the starch molecular characteristics. Int J Biol Macromol 2019; 121:120-126. [DOI: 10.1016/j.ijbiomac.2018.09.137] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 09/05/2018] [Accepted: 09/22/2018] [Indexed: 11/23/2022]
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Jardón-Valadez E, Castillo-Guajardo D, Martínez-Luis I, Gutiérrez-Sagal R, Zariñán T, Ulloa-Aguirre A. Molecular dynamics simulation of the follicle-stimulating hormone receptor. Understanding the conformational dynamics of receptor variants at positions N680 and D408 from in silico analysis. PLoS One 2018; 13:e0207526. [PMID: 30462715 PMCID: PMC6248991 DOI: 10.1371/journal.pone.0207526] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 11/01/2018] [Indexed: 11/18/2022] Open
Abstract
Follicle-stimulating hormone receptor (FSHR) is a G-protein coupled receptor (GPCR) and a prototype of the glycoprotein hormone receptors subfamily of GPCRs. Structural data of the FSHR ectodomain in complex with follicle-stimulating hormone suggests a "pull and lift" activation mechanism that triggers a conformational change on the seven α-helix transmembrane domain (TMD). To analyze the conformational changes of the FSHR TMD resulting from sequence variants associated with reproductive impairment in humans, we set up a computational approach combining helix modeling and molecular simulation methods to generate conformational ensembles of the receptor at room (300 K) and physiological (310 K) temperatures. We examined the receptor dynamics in an explicit membrane environment of polyunsaturated phospholipids and solvent water molecules. The analysis of the conformational dynamics of the functional (N680 and S680) and dysfunctional (mutations at D408) variants of the FSHR allowed us to validate the FSHR-TMD model. Functional variants display a concerted motion of flexible intracellular regions at TMD helices 5 and 6. Disruption of side chain interactions and conformational dynamics were detected upon mutation at D408 when replaced with alanine, arginine, or tyrosine. Dynamical network analysis confirmed that TMD helices 2 and 5 may share communication pathways in the functional FSHR variants, whereas no connectivity was detected in the dysfunctional mutants, indicating that the global dynamics of the FSHR was sensitive to mutations at amino acid residue 408, a key position apparently linked to misfolding and variable cell surface plasma membrane expression of FSHRs with distinct mutations at this position.
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Affiliation(s)
- Eduardo Jardón-Valadez
- Departamento de Recursos de la Tierra, Universidad Autónoma Metropolitana, Unidad Lerma, Estado de México, Mexico
| | - Derik Castillo-Guajardo
- Departamento de Ciencias Ambientales Universidad Autónoma Metropolitana, Unidad Lerma, Estado de México, Mexico
| | - Iván Martínez-Luis
- Red de Apoyo a la Investigación, National University of Mexico (UNAM) and Instituto Nacional de Ciencias Médicas y Nutrición SZ, Mexico City, Mexico
| | - Rubén Gutiérrez-Sagal
- Red de Apoyo a la Investigación, National University of Mexico (UNAM) and Instituto Nacional de Ciencias Médicas y Nutrición SZ, Mexico City, Mexico
| | - Teresa Zariñán
- Red de Apoyo a la Investigación, National University of Mexico (UNAM) and Instituto Nacional de Ciencias Médicas y Nutrición SZ, Mexico City, Mexico
| | - Alfredo Ulloa-Aguirre
- Red de Apoyo a la Investigación, National University of Mexico (UNAM) and Instituto Nacional de Ciencias Médicas y Nutrición SZ, Mexico City, Mexico
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Aguayo-Ortiz R, Straub JE, Dominguez L. Influence of membrane lipid composition on the structure and activity of γ-secretase. Phys Chem Chem Phys 2018; 20:27294-27304. [PMID: 30357233 PMCID: PMC11260083 DOI: 10.1039/c8cp04138e] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/06/2024]
Abstract
γ-Secretase (GS) is a multi-subunit membrane-embedded aspartyl protease that cleaves more than 80 integral membrane proteins, including the amyloid precursor protein (APP) to produce the amyloid-β (Aβ) peptide. Oligomerization and aggregation of the 42-amino acid length Aβ isoform in the brain has been associated with the development and progression of Alzheimer's disease (AD). Based on recent experimental structural studies and using multiscale computational modeling approaches, the conformational states and protein-membrane interactions of the GS complex embedded in six homogeneous and six heterogeneous lipid bilayers were characterized. In order to identify potential lipid and cholesterol binding sites, GS regions with high lipid/cholesterol occupancy values were analyzed using atomistic and coarse-grained simulations. Long lipid residence times were observed to be correlated with a large number of hydrogen bonds between the charged headgroups and key GS amino acids. This observation provides a plausible explanation for the inhibition of GS by charged lipids observed in previous experimental studies. Computed lateral pressure profiles suggest that higher transmembrane pressures favor active state conformations of the catalytic subunit. A probable mechanism for the regulation of the local stress response in cholesterol-rich multicomponent lipid bilayers is identified. Finally, it is demonstrated that interactions between the nicastrin extracellular domain and lipid headgroups leads to a compact structural conformation of the GS complex. Overall, this study provides valuable insight into the effect of bilayer lipid composition on the GS structural ensemble and its function.
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Affiliation(s)
- Rodrigo Aguayo-Ortiz
- Facultad de Química, Departamento de Fisicoquímica, Universidad Nacional Autónoma de México, Mexico City, 04510, Mexico.
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Padariya M, Kalathiya U, Baginski M. Structural and dynamic insights on the EmrE protein with TPP + and related substrates through molecular dynamics simulations. Chem Phys Lipids 2018; 212:1-11. [DOI: 10.1016/j.chemphyslip.2017.12.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 11/30/2017] [Accepted: 12/22/2017] [Indexed: 12/21/2022]
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Guerra F, Siemers M, Mielack C, Bondar AN. Dynamics of Long-Distance Hydrogen-Bond Networks in Photosystem II. J Phys Chem B 2018; 122:4625-4641. [PMID: 29589763 DOI: 10.1021/acs.jpcb.8b00649] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Photosystem II uses the energy of absorbed light to split water molecules, generating molecular oxygen, electrons, and protons. The four protons generated during each reaction cycle are released to the lumen via mechanisms that are poorly understood. Given the complexity of photosystem II, which consists of multiple protein subunits and cofactor molecules and hosts numerous waters, a fundamental issue is finding transient networks of hydrogen bonds that bridge potential proton donor and acceptor groups. Here, we address this issue by performing all-atom molecular dynamics simulations of wild-type and mutant photosystem II monomers, which we analyze using a new protocol designed to facilitate efficient analysis of hydrogen-bond networks. Our computations reveal that local protein/water hydrogen-bond networks can assemble transiently in photosystem II such that the reaction center connects to the lumen. The dynamics of the hydrogen-bond networks couple to the protonation state of specific carboxylate groups and are altered in a mutant with defective proton transfer. Simulations on photosystem II without its extrinsic PsbO subunit provide a molecular interpretation of the elusive functional role of this subunit.
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Affiliation(s)
- Federico Guerra
- Freie Universität Berlin, Department of Physics , Theoretical Molecular Biophysics Group , Arnimallee 14 , D-14195 Berlin , Germany
| | - Malte Siemers
- Freie Universität Berlin, Department of Physics , Theoretical Molecular Biophysics Group , Arnimallee 14 , D-14195 Berlin , Germany
| | - Christopher Mielack
- Freie Universität Berlin, Department of Physics , Theoretical Molecular Biophysics Group , Arnimallee 14 , D-14195 Berlin , Germany
| | - Ana-Nicoleta Bondar
- Freie Universität Berlin, Department of Physics , Theoretical Molecular Biophysics Group , Arnimallee 14 , D-14195 Berlin , Germany
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35
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Dynamic Water Hydrogen-Bond Networks at the Interface of a Lipid Membrane Containing Palmitoyl-Oleoyl Phosphatidylglycerol. J Membr Biol 2018. [DOI: 10.1007/s00232-018-0023-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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36
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Harris A, Saita M, Resler T, Hughes-Visentin A, Maia R, Pranga-Sellnau F, Bondar AN, Heberle J, Brown LS. Molecular details of the unique mechanism of chloride transport by a cyanobacterial rhodopsin. Phys Chem Chem Phys 2018; 20:3184-3199. [PMID: 29057415 DOI: 10.1039/c7cp06068h] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Microbial rhodopsins are well known as versatile and ubiquitous light-driven ion transporters and photosensors. While the proton transport mechanism has been studied in great detail, much less is known about various modes of anion transport. Until recently, only two main groups of light-driven anion pumps were known, archaeal halorhodopsins (HRs) and bacterial chloride pumps (known as ClRs or NTQs). Last year, another group of cyanobacterial anion pumps with a very distinct primary structure was reported. Here, we studied the chloride-transporting photocycle of a representative of this new group, Mastigocladopsis repens rhodopsin (MastR), using time-resolved spectroscopy in the infrared and visible ranges and site-directed mutagenesis. We found that, in accordance with its unique amino acid sequence containing many polar residues in the transmembrane region of the protein, its photocycle features a number of unusual molecular events not known for other anion-pumping rhodopsins. It appears that light-driven chloride ion transfers by MastR are coupled with translocation of protons and water molecules as well as perturbation of several polar sidechains. Of particular interest is transient deprotonation of Asp-85, homologous to the cytoplasmic proton donor of light-driven proton pumps (such as Asp-96 of bacteriorhodopsin), which may serve as a regulatory mechanism.
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Affiliation(s)
- Andrew Harris
- Department of Physics and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada.
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37
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Pollard AM, Sourjik V. Transmembrane region of bacterial chemoreceptor is capable of promoting protein clustering. J Biol Chem 2017; 293:2149-2158. [PMID: 29259129 DOI: 10.1074/jbc.m117.796722] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 12/06/2017] [Indexed: 11/06/2022] Open
Abstract
Many membrane proteins are known to form higher-order oligomers, but the degree to which membrane regions could facilitate protein complex assembly remains largely unclear. Clusters of chemotaxis receptors are among the most prominent structures in the bacterial cell membrane, and they play important functions in processing of chemotactic signals. Although much work has been done to elucidate mechanisms of cluster formation, it almost exclusively focused on cytoplasmic interactions among receptors and other chemotaxis proteins, whereas involvement of membrane-mediated interactions was only hypothesized. Here we used imaging of constructs composed of only a fluorescent protein and the TM helices of Tar to demonstrate that interactions between the lipid bilayer and transmembrane (TM) helices of Escherichia coli chemoreceptors alone are sufficient to mediate clustering. We found that the ability to cluster depends on the sequence or length of the TM helices, implying that certain conformations of these helices facilitate clustering, whereas others do not. Notably, observed sequence specificity was apparently consistent with differences in clustering between native E. coli receptors, with the TM sequence of better-clustering high-abundance receptors being more efficient in promoting membrane-mediated complex formation. These results indicate that being more than just membrane anchors, TM helices could play an important role in the clustering and organization of membrane proteins in bacteria.
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Affiliation(s)
- Abiola M Pollard
- From the Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), D-35043 Marburg, Germany
| | - Victor Sourjik
- From the Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), D-35043 Marburg, Germany
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38
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Kangur L, Jones MR, Freiberg A. Hydrogen bonds in the vicinity of the special pair of the bacterial reaction center probed by hydrostatic high-pressure absorption spectroscopy. Biophys Chem 2017; 231:27-33. [PMID: 28438349 DOI: 10.1016/j.bpc.2017.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 04/06/2017] [Accepted: 04/06/2017] [Indexed: 10/19/2022]
Abstract
Using the native bacteriochlorophyll a pigment cofactors as local probes, we investigated the response to external hydrostatic high pressure of reaction center membrane protein complexes from the photosynthetic bacterium Rhodobacter sphaeroides. Wild-type and engineered complexes were used with a varied number (0, 1 or 2) of hydrogen bonds that bind the reaction center primary donor bacteriochlorophyll cofactors to the surrounding protein scaffold. A pressure-induced breakage of hydrogen bonds was established for both detergent-purified and membrane-embedded reaction centers, but at rather different pressures: between 0.2 and 0.3GPa and at about 0.55GPa, respectively. The free energy change associated with the rupture of the single hydrogen bond present in wild-type reaction centers was estimated to be equal to 13-14kJ/mol. In the mutant with two symmetrical hydrogen bonds (FM197H) a single cooperative rupture of the two bonds was observed corresponding to an about twice stronger bond, rather than a sequential rupture of two individual bonds.
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Affiliation(s)
- Liina Kangur
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu, Estonia
| | - Michael R Jones
- School of Biochemistry, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, United Kingdom
| | - Arvi Freiberg
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu, Estonia; Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia.
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Bondar AN, Smith JC. Protonation-state-Coupled Conformational Dynamics in Reaction Mechanisms of Channel and Pump Rhodopsins. Photochem Photobiol 2017; 93:1336-1344. [DOI: 10.1111/php.12790] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Accepted: 04/20/2017] [Indexed: 01/27/2023]
Affiliation(s)
- Ana-Nicoleta Bondar
- Theoretical Molecular Biophysics Group; Department of Physics; Freie Universität Berlin; Berlin Germany
| | - Jeremy C. Smith
- University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics; Oak Ridge TN
- Department of Biochemistry and Cellular and Molecular Biology; University of Tennessee; Knoxville TN
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40
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Lipid-Mediated Regulation of Embedded Receptor Kinases via Parallel Allosteric Relays. Biophys J 2017; 112:643-654. [PMID: 28256224 DOI: 10.1016/j.bpj.2016.12.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 11/15/2016] [Accepted: 12/12/2016] [Indexed: 01/29/2023] Open
Abstract
Membrane-anchored receptors are essential cellular signaling elements for stimulus sensing, propagation, and transmission inside cells. However, the contributions of lipid interactions to the function and dynamics of embedded receptor kinases have not been described in detail. In this study, we used amide hydrogen/deuterium exchange mass spectrometry, a sensitive biophysical approach, to probe the dynamics of a membrane-embedded receptor kinase, EnvZ, together with functional assays to describe the role of lipids in receptor kinase function. Our results reveal that lipids play an important role in regulating receptor function through interactions with transmembrane segments, as well as through peripheral interactions with nonembedded domains. Specifically, the lipid membrane allosterically modulates the activity of the embedded kinase by altering the dynamics of a glycine-rich motif that is critical for phosphotransfer from ATP. This allostery in EnvZ is independent of membrane composition and involves direct interactions with transmembrane and periplasmic segments, as well as peripheral interactions with nonembedded domains of the protein. In the absence of the membrane-spanning regions, lipid allostery is propagated entirely through peripheral interactions. Whereas lipid allostery impacts the phosphotransferase function of the kinase, extracellular stimulus recognition is mediated via a four-helix bundle subdomain located in the cytoplasm, which functions as the osmosensing core through osmolality-dependent helical stabilization. Our findings emphasize the functional modularity in a membrane-embedded kinase, separated into membrane association, phosphotransferase function, and stimulus recognition. These components are integrated through long-range communication relays, with lipids playing an essential role in regulation.
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Venko K, Roy Choudhury A, Novič M. Computational Approaches for Revealing the Structure of Membrane Transporters: Case Study on Bilitranslocase. Comput Struct Biotechnol J 2017; 15:232-242. [PMID: 28228927 PMCID: PMC5312651 DOI: 10.1016/j.csbj.2017.01.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 01/19/2017] [Accepted: 01/20/2017] [Indexed: 11/23/2022] Open
Abstract
The structural and functional details of transmembrane proteins are vastly underexplored, mostly due to experimental difficulties regarding their solubility and stability. Currently, the majority of transmembrane protein structures are still unknown and this present a huge experimental and computational challenge. Nowadays, thanks to X-ray crystallography or NMR spectroscopy over 3000 structures of membrane proteins have been solved, among them only a few hundred unique ones. Due to the vast biological and pharmaceutical interest in the elucidation of the structure and the functional mechanisms of transmembrane proteins, several computational methods have been developed to overcome the experimental gap. If combined with experimental data the computational information enables rapid, low cost and successful predictions of the molecular structure of unsolved proteins. The reliability of the predictions depends on the availability and accuracy of experimental data associated with structural information. In this review, the following methods are proposed for in silico structure elucidation: sequence-dependent predictions of transmembrane regions, predictions of transmembrane helix–helix interactions, helix arrangements in membrane models, and testing their stability with molecular dynamics simulations. We also demonstrate the usage of the computational methods listed above by proposing a model for the molecular structure of the transmembrane protein bilitranslocase. Bilitranslocase is bilirubin membrane transporter, which shares similar tissue distribution and functional properties with some of the members of the Organic Anion Transporter family and is the only member classified in the Bilirubin Transporter Family. Regarding its unique properties, bilitranslocase is a potentially interesting drug target.
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Affiliation(s)
- Katja Venko
- Department of Cheminformatics, National Institute of Chemistry, Ljubljana, Slovenia
| | - A Roy Choudhury
- Department of Cheminformatics, National Institute of Chemistry, Ljubljana, Slovenia
| | - Marjana Novič
- Department of Cheminformatics, National Institute of Chemistry, Ljubljana, Slovenia
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42
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Fischermeier E, Pospíšil P, Sayed A, Hof M, Solioz M, Fahmy K. Dipolar Relaxation Dynamics at the Active Site of an ATPase Regulated by Membrane Lateral Pressure. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201611582] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Elisabeth Fischermeier
- Helmholtz-Zentrum Dresden-Rossendorf Institute of Resource Ecology Bautzner Landstrasse 400 01328 Dresden Germany
- Technische Universität Dresden Biotechnology Center Tatzberg 47-49, 01307 Dresden Germany
- Nationales Zentrum für Tumorerkrankungen Heidelberg Im Neuenheimer Feld 460 69120 Heidelberg Germany
| | - Petr Pospíšil
- J. Heyrovský Inst. Physical Chemistry of the A.S.C.R. v.v.i. Prague Czech Republic
| | - Ahmed Sayed
- Helmholtz-Zentrum Dresden-Rossendorf Institute of Resource Ecology Bautzner Landstrasse 400 01328 Dresden Germany
- Technische Universität Dresden Biotechnology Center Tatzberg 47-49, 01307 Dresden Germany
- Institute for Experimental Physics I Universität Leipzig Linnéstrasse 5 04103 Leipzig Germany
| | - Martin Hof
- J. Heyrovský Inst. Physical Chemistry of the A.S.C.R. v.v.i. Prague Czech Republic
| | - Marc Solioz
- University of Bern Dept. of Clinical Pharmacology Murtenstrasse 35 3008 Bern Switzerland
| | - Karim Fahmy
- Helmholtz-Zentrum Dresden-Rossendorf Institute of Resource Ecology Bautzner Landstrasse 400 01328 Dresden Germany
- Technische Universität Dresden Biotechnology Center Tatzberg 47-49, 01307 Dresden Germany
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Fischermeier E, Pospíšil P, Sayed A, Hof M, Solioz M, Fahmy K. Dipolar Relaxation Dynamics at the Active Site of an ATPase Regulated by Membrane Lateral Pressure. Angew Chem Int Ed Engl 2016; 56:1269-1272. [DOI: 10.1002/anie.201611582] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Indexed: 01/07/2023]
Affiliation(s)
- Elisabeth Fischermeier
- Helmholtz-Zentrum Dresden-Rossendorf Institute of Resource Ecology Bautzner Landstrasse 400 01328 Dresden Germany
- Technische Universität Dresden Biotechnology Center Tatzberg 47-49, 01307 Dresden Germany
- Nationales Zentrum für Tumorerkrankungen Heidelberg Im Neuenheimer Feld 460 69120 Heidelberg Germany
| | - Petr Pospíšil
- J. Heyrovský Inst. Physical Chemistry of the A.S.C.R. v.v.i. Prague Czech Republic
| | - Ahmed Sayed
- Helmholtz-Zentrum Dresden-Rossendorf Institute of Resource Ecology Bautzner Landstrasse 400 01328 Dresden Germany
- Technische Universität Dresden Biotechnology Center Tatzberg 47-49, 01307 Dresden Germany
- Institute for Experimental Physics I Universität Leipzig Linnéstrasse 5 04103 Leipzig Germany
| | - Martin Hof
- J. Heyrovský Inst. Physical Chemistry of the A.S.C.R. v.v.i. Prague Czech Republic
| | - Marc Solioz
- University of Bern Dept. of Clinical Pharmacology Murtenstrasse 35 3008 Bern Switzerland
| | - Karim Fahmy
- Helmholtz-Zentrum Dresden-Rossendorf Institute of Resource Ecology Bautzner Landstrasse 400 01328 Dresden Germany
- Technische Universität Dresden Biotechnology Center Tatzberg 47-49, 01307 Dresden Germany
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Bondar AN. Biophysical mechanism of rhomboid proteolysis: Setting a foundation for therapeutics. Semin Cell Dev Biol 2016; 60:46-51. [DOI: 10.1016/j.semcdb.2016.09.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Revised: 08/12/2016] [Accepted: 09/12/2016] [Indexed: 11/16/2022]
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45
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Milenkovic S, Bondar AN. Mechanism of conformational coupling in SecA: Key role of hydrogen-bonding networks and water interactions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:374-85. [PMID: 26607006 DOI: 10.1016/j.bbamem.2015.11.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 11/05/2015] [Accepted: 11/18/2015] [Indexed: 11/16/2022]
Abstract
SecA uses the energy yielded by the binding and hydrolysis of adenosine triphosphate (ATP) to push secretory pre-proteins across the plasma membrane in bacteria. Hydrolysis of ATP occurs at the nucleotide-binding site, which contains the conserved carboxylate groups of the DEAD-box helicases. Although crystal structures provide valuable snapshots of SecA along its reaction cycle, the mechanism that ensures conformational coupling between the nucleotide-binding site and the other domains of SecA remains unclear. The observation that SecA contains numerous hydrogen-bonding groups raises important questions about the role of hydrogen-bonding networks and hydrogen-bond dynamics in long-distance conformational couplings. To address these questions, we explored the molecular dynamics of SecA from three different organisms, with and without bound nucleotide, in water. By computing two-dimensional hydrogen-bonding maps we identify networks of hydrogen bonds that connect the nucleotide-binding site to remote regions of the protein, and sites in the protein that respond to specific perturbations. We find that the nucleotide-binding site of ADP-bound SecA has a preferred geometry whereby the first two carboxylates of the DEAD motif bridge via hydrogen-bonding water. Simulations of a mutant with perturbed ATP hydrolysis highlight the water-bridged geometry as a key structural element of the reaction path.
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Affiliation(s)
- Stefan Milenkovic
- Theoretical Molecular Biophysics, Department of Physics, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - Ana-Nicoleta Bondar
- Theoretical Molecular Biophysics, Department of Physics, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin, Germany.
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46
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Cournia Z, Allen TW, Andricioaei I, Antonny B, Baum D, Brannigan G, Buchete NV, Deckman JT, Delemotte L, del Val C, Friedman R, Gkeka P, Hege HC, Hénin J, Kasimova MA, Kolocouris A, Klein ML, Khalid S, Lemieux MJ, Lindow N, Roy M, Selent J, Tarek M, Tofoleanu F, Vanni S, Urban S, Wales DJ, Smith JC, Bondar AN. Membrane Protein Structure, Function, and Dynamics: a Perspective from Experiments and Theory. J Membr Biol 2015; 248:611-40. [PMID: 26063070 PMCID: PMC4515176 DOI: 10.1007/s00232-015-9802-0] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 03/26/2015] [Indexed: 01/05/2023]
Abstract
Membrane proteins mediate processes that are fundamental for the flourishing of biological cells. Membrane-embedded transporters move ions and larger solutes across membranes; receptors mediate communication between the cell and its environment and membrane-embedded enzymes catalyze chemical reactions. Understanding these mechanisms of action requires knowledge of how the proteins couple to their fluid, hydrated lipid membrane environment. We present here current studies in computational and experimental membrane protein biophysics, and show how they address outstanding challenges in understanding the complex environmental effects on the structure, function, and dynamics of membrane proteins.
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Affiliation(s)
- Zoe Cournia
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527, Athens, Greece
| | - Toby W. Allen
- School of Applied Sciences & Health Innovations Research Institute, RMIT University, GPO Box 2476, Melbourne, Vic, 3001, Australia; and Department of Chemistry, University of California, Davis. Davis, CA 95616, USA
| | - Ioan Andricioaei
- Department of Chemistry, University of California, Irvine, CA 92697
| | - Bruno Antonny
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis and Centre National de la Recherche Scientifique, UMR 7275, 06560 Valbonne, France
| | - Daniel Baum
- Department of Visualization and Data Analysis, Zuse Institute Berlin, Takustrasse 7, D-14195 Berlin, Germany
| | - Grace Brannigan
- Center for Computational and Integrative Biology and Department of Physics, Rutgers University-Camden, Camden, NJ, USA
| | - Nicolae-Viorel Buchete
- School of Physics and Complex and Adaptive Systems Laboratory, University College Dublin, Belfield, Dublin 4, Ireland
| | | | - Lucie Delemotte
- Institute of Computational and Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Coral del Val
- Department of Artificial Intelligence, University of Granada, E-18071 Granada, Spain
| | - Ran Friedman
- Linnæus University, Department of Chemistry and Biomedical Sciences & Centre for Biomaterials Chemistry, 391 82 Kalmar, Sweden
| | - Paraskevi Gkeka
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527, Athens, Greece
| | - Hans-Christian Hege
- Department of Visualization and Data Analysis, Zuse Institute Berlin, Takustrasse 7, D-14195 Berlin, Germany
| | - Jérôme Hénin
- Laboratoire de Biochimie Théorique, IBPC and CNRS, Paris, France
| | - Marina A. Kasimova
- Université de Lorraine, SRSMC, UMR 7565, Vandoeuvre-lès-Nancy, F-54500, France
- Lomonosov Moscow State University, Moscow, 119991, Russian Federation
| | - Antonios Kolocouris
- Faculty of Pharmacy, Department of Pharmaceutical Chemistry, University of Athens, Panepistimioupolis-Zografou, 15771 Athens, Greece
| | - Michael L. Klein
- Institute of Computational and Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Syma Khalid
- Department of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, UK
| | - M. Joanne Lemieux
- Department of Biochemistry, Faculty of Medicine & Dentistry, Membrane Protein Disease Research Group, and Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
| | - Norbert Lindow
- Department of Visualization and Data Analysis, Zuse Institute Berlin, Takustrasse 7, D-14195 Berlin, Germany
| | - Mahua Roy
- Department of Chemistry, University of California, Irvine
| | - Jana Selent
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences, Universitat Pompeu Fabra, IMIM (Hospital del Mar Medical Research Institute), Dr. Aiguader 88, E-08003 Barcelona, Spain
| | - Mounir Tarek
- Université de Lorraine, SRSMC, UMR 7565, Vandoeuvre-lès-Nancy, F-54500, France
- CNRS, SRSMC, UMR 7565, Vandoeuvre-lès-Nancy, F-54500, France
| | - Florentina Tofoleanu
- School of Physics and Complex and Adaptive Systems Laboratory, University College Dublin, Belfield, Dublin 4, Ireland
| | - Stefano Vanni
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis and Centre National de la Recherche Scientifique, UMR 7275, 06560 Valbonne, France
| | - Sinisa Urban
- Johns Hopkins University School of Medicine, Howard Hughes Medical Institute, Department of Molecular Biology & Genetics, 725 N. Wolfe Street, 507 Preclinical Teaching Building, Baltimore, MD 21205, USA
| | - David J. Wales
- University Chemical Laboratories, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Jeremy C. Smith
- Oak Ridge National Laboratory, PO BOX 2008 MS6309, Oak Ridge, TN 37831-6309, USA
| | - Ana-Nicoleta Bondar
- Theoretical Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
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47
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Dai X, Zhang Y, Gao L, Bai T, Wang W, Cui Y, Liu W. A Mechanically Strong, Highly Stable, Thermoplastic, and Self-Healable Supramolecular Polymer Hydrogel. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:3566-3571. [PMID: 25946310 DOI: 10.1002/adma.201500534] [Citation(s) in RCA: 481] [Impact Index Per Article: 53.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Revised: 04/06/2015] [Indexed: 06/04/2023]
Abstract
Polymerization of glycinamide-conjugated monomer alone in concentrated aqueous solution enables facile formation of a mechanically strong and a highly stable supramolecular polymer (SP) hydrogel because of the cooperatively hydrogen-bonded crosslinking and strengthening effect from dual amide motifs. This SP hydrogel exhibits thermoplastic processability, injectability, and self-reparability because of the dynamic destruction and reconstruction of hydrogen bonds in response to temperature change.
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Affiliation(s)
- Xiyang Dai
- School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin, 300072, PR China
| | - Yinyu Zhang
- School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin, 300072, PR China
| | - Lina Gao
- Research Center of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 300193, PR China
| | - Tao Bai
- School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin, 300072, PR China
| | - Wei Wang
- School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin, 300072, PR China
| | - Yuanlu Cui
- Research Center of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 300193, PR China
| | - Wenguang Liu
- School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin, 300072, PR China
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48
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Jardón-Valadez E, Bondar AN, Tobias DJ. Electrostatic interactions and hydrogen bond dynamics in chloride pumping by halorhodopsin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1837:1964-1972. [PMID: 25256652 DOI: 10.1016/j.bbabio.2014.09.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 09/15/2014] [Accepted: 09/17/2014] [Indexed: 10/24/2022]
Abstract
Translocation of negatively charged ions across cell membranes by ion pumps raises the question as to how protein interactions control the location and dynamics of the ion. Here we address this question by performing extensive molecular dynamics simulations of wild type and mutant halorhodopsin, a seven-helical transmembrane protein that translocates chloride ions upon light absorption. We find that inter-helical hydrogen bonds mediated by a key arginine group largely govern the dynamics of the protein and water groups coordinating the chloride ion.
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Affiliation(s)
- Eduardo Jardón-Valadez
- Departamento de Recursos de la Tierra, Universidad Autónoma Metropolitana-Lerma, Lerma de Villada, Estado de México 52005, México
| | - Ana-Nicoleta Bondar
- Theoretical Molecular Biophysics Department of Physics, Freie University Arnimallee 14, Berlin 14195, Germany.
| | - Douglas J Tobias
- Department of Chemistry, University of California, Irvine, CA 92697-2025, USA
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49
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Correa-Basurto J, Cuevas-Hernández RI, Phillips-Farfán BV, Martínez-Archundia M, Romo-Mancillas A, Ramírez-Salinas GL, Pérez-González ÓA, Trujillo-Ferrara J, Mendoza-Torreblanca JG. Identification of the antiepileptic racetam binding site in the synaptic vesicle protein 2A by molecular dynamics and docking simulations. Front Cell Neurosci 2015; 9:125. [PMID: 25914622 PMCID: PMC4392693 DOI: 10.3389/fncel.2015.00125] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 03/17/2015] [Indexed: 01/21/2023] Open
Abstract
Synaptic vesicle protein 2A (SV2A) is an integral membrane protein necessary for the proper function of the central nervous system and is associated to the physiopathology of epilepsy. SV2A is the molecular target of the anti-epileptic drug levetiracetam and its racetam analogs. The racetam binding site in SV2A and the non-covalent interactions between racetams and SV2A are currently unknown; therefore, an in silico study was performed to explore these issues. Since SV2A has not been structurally characterized with X-ray crystallography or nuclear magnetic resonance, a three-dimensional (3D) model was built. The model was refined by performing a molecular dynamics simulation (MDS) and the interactions of SV2A with the racetams were determined by docking studies. A reliable 3D model of SV2A was obtained; it reached structural equilibrium during the last 15 ns of the MDS (50 ns) with remaining structural motions in the N-terminus and long cytoplasmic loop. The docking studies revealed that hydrophobic interactions and hydrogen bonds participate importantly in ligand recognition within the binding site. Residues T456, S665, W666, D670 and L689 were important for racetam binding within the trans-membrane hydrophilic core of SV2A. Identifying the racetam binding site within SV2A should facilitate the synthesis of suitable radio-ligands to study treatment response and possibly epilepsy progression.
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Affiliation(s)
- José Correa-Basurto
- Laboratorio de Modelado Molecular y Diseño de fármacos, Departamento de Bioquímica de la Escuela Superior de Medicina del Instituto Politécnico Nacional, México City Mexico
| | - Roberto I Cuevas-Hernández
- Laboratorio de Modelado Molecular y Diseño de fármacos, Departamento de Bioquímica de la Escuela Superior de Medicina del Instituto Politécnico Nacional, México City Mexico
| | - Bryan V Phillips-Farfán
- Laboratorio de Nutrición Experimental, Laboratorio de Oncología Experimental and Laboratorio de Neuroquímica, Instituto Nacional de Pediatría, México City Mexico
| | - Marlet Martínez-Archundia
- Laboratorio de Modelado Molecular y Diseño de fármacos, Departamento de Bioquímica de la Escuela Superior de Medicina del Instituto Politécnico Nacional, México City Mexico
| | - Antonio Romo-Mancillas
- División de Estudios de Posgrado, Facultad de Química, Universidad Autónoma de Querétaro, Santiago de Querétaro Mexico
| | - Gema L Ramírez-Salinas
- Laboratorio de Modelado Molecular y Diseño de fármacos, Departamento de Bioquímica de la Escuela Superior de Medicina del Instituto Politécnico Nacional, México City Mexico
| | - Óscar A Pérez-González
- Laboratorio de Nutrición Experimental, Laboratorio de Oncología Experimental and Laboratorio de Neuroquímica, Instituto Nacional de Pediatría, México City Mexico
| | - José Trujillo-Ferrara
- Laboratorio de Modelado Molecular y Diseño de fármacos, Departamento de Bioquímica de la Escuela Superior de Medicina del Instituto Politécnico Nacional, México City Mexico
| | - Julieta G Mendoza-Torreblanca
- Laboratorio de Nutrición Experimental, Laboratorio de Oncología Experimental and Laboratorio de Neuroquímica, Instituto Nacional de Pediatría, México City Mexico
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50
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Shelar A, Bansal M. Sequence and conformational preferences at termini of α-helices in membrane proteins: role of the helix environment. Proteins 2014; 82:3420-36. [PMID: 25257385 DOI: 10.1002/prot.24696] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/05/2014] [Accepted: 09/16/2014] [Indexed: 11/09/2022]
Abstract
α-Helices are amongst the most common secondary structural elements seen in membrane proteins and are packed in the form of helix bundles. These α-helices encounter varying external environments (hydrophobic, hydrophilic) that may influence the sequence preferences at their N and C-termini. The role of the external environment in stabilization of the helix termini in membrane proteins is still unknown. Here we analyze α-helices in a high-resolution dataset of integral α-helical membrane proteins and establish that their sequence and conformational preferences differ from those in globular proteins. We specifically examine these preferences at the N and C-termini in helices initiating/terminating inside the membrane core as well as in linkers connecting these transmembrane helices. We find that the sequence preferences and structural motifs at capping (Ncap and Ccap) and near-helical (N' and C') positions are influenced by a combination of features including the membrane environment and the innate helix initiation and termination property of residues forming structural motifs. We also find that a large number of helix termini which do not form any particular capping motif are stabilized by formation of hydrogen bonds and hydrophobic interactions contributed from the neighboring helices in the membrane protein. We further validate the sequence preferences obtained from our analysis with data from an ultradeep sequencing study that identifies evolutionarily conserved amino acids in the rat neurotensin receptor. The results from our analysis provide insights for the secondary structure prediction, modeling and design of membrane proteins.
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Affiliation(s)
- Ashish Shelar
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, Karnataka, India
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