1
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Sahu S, Saini R, Debnath A. Chlorophyll-Induced Lamellar to Nonlamellar Phase Transitions and Dynamical Heterogeneity in Plant Thylakoid Membranes. J Phys Chem B 2024; 128:10154-10164. [PMID: 39370833 DOI: 10.1021/acs.jpcb.4c04164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/08/2024]
Abstract
Chlorophyll a (CLA) pigments and thylakoid membranes are crucial components of plants for photosynthesis. To understand the effect of CLA on the structure and dynamics of thylakoid membranes, coarse-grained molecular dynamics (CG MD) simulations of thylakoid membranes are performed by varying the numbers of CLA at 293 K using MARTINI-2 force fields. The membrane undergoes a lamellar to nonlamellar phase transition above a critical concentration of CLA. The CLAs dynamically form aggregates of different orders and preferentially fetch the least unsaturated nonbilayer-forming lipids around them, resulting in a nonlamellar phase with fused regions. These fused regions cause a structural arrest of CLA and lipids, inducing dynamic heterogeneity manifested by non-Gaussian parameters and van Hove correlation functions. The lamellar to nonlamellar phase transition of the membrane is associated with a drastic reduction in correlation length of the immobile CLA and lipids governed by the fused topology. Such insights into CLA-induced structural transitions in thylakoid membranes are pertinent for understanding nonphotochemical quenching mechanisms and hold promise for designing future artificial photosynthetic materials and applications in photodynamic therapy.
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Affiliation(s)
- Samapika Sahu
- Department of Chemistry, IIT Jodhpur, Jodhpur, Rajasthan 342037, India
| | - Renu Saini
- Department of Chemistry, IIT Jodhpur, Jodhpur, Rajasthan 342037, India
| | - Ananya Debnath
- Department of Chemistry, IIT Jodhpur, Jodhpur, Rajasthan 342037, India
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2
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Wang L, Yang Z, Satoshi F, Prasanna X, Yan Z, Vihinen H, Chen Y, Zhao Y, He X, Bu Q, Li H, Zhao Y, Jiang L, Qin F, Dai Y, Zhang N, Qin M, Kuang W, Zhao Y, Jokitalo E, Vattulainen I, Kajander T, Zhao H, Cen X. Membrane remodeling by FAM92A1 during brain development regulates neuronal morphology, synaptic function, and cognition. Nat Commun 2024; 15:6209. [PMID: 39043703 PMCID: PMC11266426 DOI: 10.1038/s41467-024-50565-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 07/12/2024] [Indexed: 07/25/2024] Open
Abstract
The Bin/Amphiphysin/Rvs (BAR) domain protein FAM92A1 is a multifunctional protein engaged in regulating mitochondrial ultrastructure and ciliogenesis, but its physiological role in the brain remains unclear. Here, we show that FAM92A1 is expressed in neurons starting from embryonic development. FAM92A1 knockout in mice results in altered brain morphology and age-associated cognitive deficits, potentially due to neuronal degeneration and disrupted synaptic plasticity. Specifically, FAM92A1 deficiency impairs diverse neuronal membrane morphology, including the mitochondrial inner membrane, myelin sheath, and synapses, indicating its roles in membrane remodeling and maintenance. By determining the crystal structure of the FAM92A1 BAR domain, combined with atomistic molecular dynamics simulations, we uncover that FAM92A1 interacts with phosphoinositide- and cardiolipin-containing membranes to induce lipid-clustering and membrane curvature. Altogether, these findings reveal the physiological role of FAM92A1 in the brain, highlighting its impact on synaptic plasticity and neural function through the regulation of membrane remodeling and endocytic processes.
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Affiliation(s)
- Liang Wang
- Mental Health Center and National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, China
- Faculty of Biological and Environmental Sciences, University of Helsinki, 00014, Helsinki, Finland
| | - Ziyun Yang
- Mental Health Center and National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Fudo Satoshi
- Helsinki Institute of Life Science - Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Xavier Prasanna
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Ziyi Yan
- Faculty of Biological and Environmental Sciences, University of Helsinki, 00014, Helsinki, Finland
| | - Helena Vihinen
- Helsinki Institute of Life Science (HiLIFE) - Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Yaxing Chen
- Mental Health Center and National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Yue Zhao
- Mental Health Center and National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Xiumei He
- Mental Health Center and National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, China
- School of Life Sciences, Guangxi Normal University, Guilin, China
- Guangxi Universities Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, 541004, China
| | - Qian Bu
- Mental Health Center and National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Hongchun Li
- Mental Health Center and National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Ying Zhao
- Mental Health Center and National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Linhong Jiang
- Mental Health Center and National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Feng Qin
- Mental Health Center and National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Yanping Dai
- Mental Health Center and National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Ni Zhang
- Mental Health Center, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Meng Qin
- Mental Health Center and National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Weihong Kuang
- Mental Health Center, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Yinglan Zhao
- Mental Health Center and National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Eija Jokitalo
- Helsinki Institute of Life Science (HiLIFE) - Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Tommi Kajander
- Helsinki Institute of Life Science - Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Hongxia Zhao
- Faculty of Biological and Environmental Sciences, University of Helsinki, 00014, Helsinki, Finland.
- School of Life Sciences, Guangxi Normal University, Guilin, China.
- Guangxi Universities Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, 541004, China.
| | - Xiaobo Cen
- Mental Health Center and National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, China.
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3
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Majumder A, Straub JE. Machine Learning Derived Collective Variables for the Study of Protein Homodimerization in Membrane. J Chem Theory Comput 2024; 20:5774-5783. [PMID: 38918177 DOI: 10.1021/acs.jctc.4c00454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
The accurate calculation of equilibrium constants for protein-protein association is of fundamental importance to quantitative biology and remains an outstanding challenge for computational biophysics. Traditionally, equilibrium constants have been computed from one-dimensional free energy surfaces derived from sampling along a single collective variable. Importantly, recent advances in enhanced sampling methodology have facilitated the characterization of multidimensional free energy landscapes, often exposing multiple thermodynamically important minima missed by more restrictive sampling methods. A key to the effectiveness of this multidimensional sampling approach is the identification of collective variables that effectively define the configurational space of dissociated and associated states. Here we present the application of two machine learning methods for the unbiased determination of collective variables for enhanced sampling and analysis of protein-protein association. Our results both validate prior work, based on intuition derived collective variables, and demonstrate the effectiveness of the machine learning methods for the identification of collective variables for association reactions in complex biomolecular systems.
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Affiliation(s)
- Ayan Majumder
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - John E Straub
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
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4
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Fábián B, Javanainen M. Energetics of the Transmembrane Peptide Sorting by Hydrophobic Mismatch. J Phys Chem Lett 2024; 15:5344-5349. [PMID: 38738950 PMCID: PMC11129306 DOI: 10.1021/acs.jpclett.4c00651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 04/25/2024] [Accepted: 04/26/2024] [Indexed: 05/14/2024]
Abstract
Hydrophobic mismatch between a lipid membrane and embedded transmembrane peptides or proteins plays a role in their lateral localization and function. Earlier studies have resolved numerous mechanisms through which the peptides and membrane proteins adapt to mismatch, yet the energetics of lateral sorting due to hydrophobic mismatch have remained elusive due to the lack of suitable computational or experimental protocols. Here, we pioneer a molecular dynamics simulation approach to study the sorting of peptides along a membrane thickness gradient. Peptides of different lengths tilt and diffuse along the membrane to eliminate mismatch with a rate directly proportional to the magnitude of mismatch. We extract the 2-dimensional free energy profiles as a function of local thickness and peptide orientation, revealing the relative contributions of sorting and tilting, and suggesting their thermally accessible regimes. Our approach can readily be applied to study other membrane systems of biological interest where hydrophobic mismatch, or membrane thickness in general, plays a role.
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Affiliation(s)
- Balázs Fábián
- Department
of Theoretical Biophysics, MPI Biophysics, DE-60438 Frankfurt
am Main, Germany
| | - Matti Javanainen
- Institute
of Biotechnology, University of Helsinki, FI-00790 Helsinki, Finland
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5
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Allen P, Smith AC, Benedicto V, Abdulhasan A, Narayanaswami V, Tapavicza E. Molecular dynamics simulation of apolipoprotein E3 lipid nanodiscs. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184230. [PMID: 37704040 PMCID: PMC11318356 DOI: 10.1016/j.bbamem.2023.184230] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Revised: 09/06/2023] [Accepted: 09/07/2023] [Indexed: 09/15/2023]
Abstract
Nanodiscs are binary discoidal complexes of a phospholipid bilayer circumscribed by belt-like helical scaffold proteins. Using coarse-grained and all-atom molecular dynamics simulations, we explore the stability, size, and structure of nanodiscs formed between the N-terminal domain of apolipoprotein E3 (apoE3-NT) and variable number of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) molecules. We study both parallel and antiparallel double-belt configurations, consisting of four proteins per nanodisc. Our simulations predict nanodiscs containing between 240 and 420 DMPC molecules to be stable. The antiparallel configurations exhibit an average of 1.6 times more amino acid interactions between protein chains and 2 times more ionic contacts, compared to the parallel configuration. With one exception, DMPC order parameters are consistently larger in the antiparallel configuration than in the parallel one. In most cases, the root mean square deviation of the positions of the protein backbone atoms is smaller in the antiparallel configuration. We further report nanodisc size, thickness, radius of gyration, and solvent accessible surface area. Combining all investigated parameters, we hypothesize the antiparallel protein configuration leading to more stable and more rigid nanodiscs than the parallel one.
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Affiliation(s)
- Patrick Allen
- Department of Chemistry and Biochemistry, California State University, Long Beach, 1250 Bellflower Boulevard, Long Beach, 90840, CA, USA
| | - Adam C Smith
- Department of Chemistry and Biochemistry, California State University, Long Beach, 1250 Bellflower Boulevard, Long Beach, 90840, CA, USA
| | - Vernon Benedicto
- Department of Chemistry and Biochemistry, California State University, Long Beach, 1250 Bellflower Boulevard, Long Beach, 90840, CA, USA
| | - Abbas Abdulhasan
- Department of Chemistry and Biochemistry, California State University, Long Beach, 1250 Bellflower Boulevard, Long Beach, 90840, CA, USA
| | - Vasanthy Narayanaswami
- Department of Chemistry and Biochemistry, California State University, Long Beach, 1250 Bellflower Boulevard, Long Beach, 90840, CA, USA
| | - Enrico Tapavicza
- Department of Chemistry and Biochemistry, California State University, Long Beach, 1250 Bellflower Boulevard, Long Beach, 90840, CA, USA.
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6
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Saini R, Debnath A. Thylakoid Composition Facilitates Chlorophyll a Dimerization through Stronger Interlipid Interactions. J Phys Chem B 2023; 127:9082-9094. [PMID: 37819861 DOI: 10.1021/acs.jpcb.3c04942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Plant thylakoid membrane serves as a crucial matrix for the aggregation of chlororophyll a (CLA) pigments, essential for light harvesting. To understand the role of lipid compositions in the stability of CLA aggregates, dimerization of chlorophyll a molecules (CLA) is studied in the presence of the thylakoid and the bilayers comprising either the least or the highest unsaturated lipids by using coarse-grained molecular dynamics simulations. The thylakoid membrane enhances the stability of the CLA dimer compared with other membranes due to very strong lipid-lipid interactions. The thylakoid exhibits a distinct distribution of lipids around the CLA dimer. Less unsaturated lipids reside in close proximity to the dimer, promoting increased order and efficient packing. Conversely, higher unsaturated lipids are depleted from the dimer, imparting flexibility to the membrane. The combination of tight packing near the dimer and membrane flexibility away from the dimer enhances the stability of the dimer in the thylakoid membrane. Our results suggest that lipid mixing, rather than lipid unsaturation, plays a critical role in facilitating CLA dimerization by modulating the membrane microenvironment through stronger lipid-lipid interactions. These insights will be useful in understanding how lipid compositions affect efficient light absorption and energy transfer during photosynthesis in the future.
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Affiliation(s)
- Renu Saini
- Department of Chemistry, Indian Institute of Technology, Jodhpur, Rajasthan 342030, India
| | - Ananya Debnath
- Department of Chemistry, Indian Institute of Technology, Jodhpur, Rajasthan 342030, India
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7
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Majumder A, Straub JE. The role of structural heterogeneity in the homodimerization of transmembrane proteins. J Chem Phys 2023; 159:134101. [PMID: 37782254 PMCID: PMC10547497 DOI: 10.1063/5.0159801] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 07/27/2023] [Indexed: 10/03/2023] Open
Abstract
The equilibrium association of transmembrane proteins plays a fundamental role in membrane protein function and cellular signaling. While the study of the equilibrium binding of single pass transmembrane proteins has received significant attention in experiment and simulation, the accurate assessment of equilibrium association constants remains a challenge to experiment and simulation. In experiment, there remain wide variations in association constants derived from experimental studies of the most widely studied transmembrane proteins. In simulation, state-of-the art methods have failed to adequately sample the thermodynamically relevant structures of the dimer state ensembles using coarse-grained models. In addition, all-atom force fields often fail to accurately assess the relative free energies of the dimer and monomer states. Given the importance of this fundamental biophysical process, it is essential to address these shortcomings. In this work, we establish an effective computational protocol for the calculation of equilibrium association constants for transmembrane homodimer formation. A set of transmembrane protein homodimers, used in the parameterization of the MARTINI v3 force field, are simulated using metadynamics, based on three collective variables. The method is found to be accurate and computationally efficient, providing a standard to be used in the future simulation studies using coarse-grained or all-atom models.
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Affiliation(s)
- Ayan Majumder
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
| | - John E. Straub
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
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8
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MacDermott-Opeskin HI, Wilson KA, O'Mara ML. The Impact of Antimicrobial Peptides on the Acinetobacter baumannii Inner Membrane Is Modulated by Lipid Polyunsaturation. ACS Infect Dis 2023; 9:815-826. [PMID: 36920795 DOI: 10.1021/acsinfecdis.2c00530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
The Gram-negative pathogen Acinetobacter baumannii is a primary contributor to nosocomial multi-drug-resistant (MDR) infections. To combat the rise of MDR infections, novel features of A. baumannii need to be considered for the development of new treatment options. One such feature is the preferential scavenging of exogenous lipids, including host-derived polyunsaturated fatty acids (PUFAs), for membrane phospholipid synthesis. These alterations in membrane composition impact both the lipid chemistry and the membrane biophysical properties. In this work we examine how antimicrobial peptides (AMPs) interact with the inner membranes of A. baumannii in the presence and absence of polyunsaturated phospholipids. Using coarse-grained molecular dynamics simulations of complex A. baumannii inner membrane models derived from lipidomes of bacteria grown in the presence and absence of PUFAs, we examine the impact of the adsorption of four prototypical AMPs (CAMEL, LL-37, pexiganan, and magainin-2) on the membrane biophysical properties. Our simulations reveal that the impact of AMP adsorption on the membrane biophysical properties was dependent on both the membrane composition and the specific AMP involved. Both lipid headgroup charge and tail unsaturation played important roles in driving the interactions that occurred both within the membrane and between the membrane and AMPs. The changes to the membrane biophysical properties also showed a complex relationship with the AMP's physical properties, such as AMP charge, chain length, and charge-to-mass ratio. Cumulatively, this work highlights the importance of studying AMPs using a complex membrane environment and provides insights into the mechanistic action of AMPs in polyunsaturated lipid-rich bacterial membranes.
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Affiliation(s)
- Hugo I MacDermott-Opeskin
- Research School of Chemistry, College of Science, The Australian National University, Canberra, ACT 2601, Australia
| | - Katie A Wilson
- Research School of Chemistry, College of Science, The Australian National University, Canberra, ACT 2601, Australia.,Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL A1C 5S7 Canada
| | - Megan L O'Mara
- Research School of Chemistry, College of Science, The Australian National University, Canberra, ACT 2601, Australia.,Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia
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9
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Yano Y, Morise T, Matsuzaki K. Effects of Gly Residue and Cholesterol on the GXXXG-Mediated Parallel Association of Transmembrane Helices: A Single-Pair FRET Study. Chembiochem 2022; 23:e202200160. [PMID: 36229427 DOI: 10.1002/cbic.202200160] [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: 03/23/2022] [Revised: 10/12/2022] [Indexed: 01/25/2023]
Abstract
Small residue-mediated interhelical packing is ubiquitous in helical membrane proteins: however, the lipid dependence of its stability remains unclear. We previously demonstrated that the introduction of a GXXXG sequence in the middle of de novo-designed (AALALAA)3 helices (AALALAA AGLALGA AALALAA) facilitated their dimerization, which was abolished by cholesterol. Here single-pair FRET measurements revealed that a longer GXXXGXXXG segment (AALALAA A GLALGA AAGALAA) promoted helix dimerization in POPC/cholesterol bilayers, but not without cholesterol. The predicted dimer structures and degrees of helix packing suggested that helix dimers with small (∼10°) and large (∼55°) crossing angles were only stabilized in POPC and POPC/cholesterol membranes, respectively. A steric hindrance in the dimer interface and the large flexibility of helices prevented the formation of stable dimers. Therefore, amino acid sequences and lipid compositions distinctively constrain stable dimer structures in membranes.
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Affiliation(s)
- Yoshiaki Yano
- School of Pharmacy and Pharmaceutical Sciences, Mukogawa Woman's University, Nishinomiya, 663-8179, Japan
| | - Takayuki Morise
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
| | - Katsumi Matsuzaki
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
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10
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Ho TH, Nguyen TT, Huynh LK. Formation of lipid raft nanodomains in homogeneous ternary lipid mixture of POPC/DPSM/cholesterol: Theoretical insights. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:184027. [PMID: 35995208 DOI: 10.1016/j.bbamem.2022.184027] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 07/16/2022] [Accepted: 08/04/2022] [Indexed: 06/15/2023]
Abstract
Lipid rafts, in biological membranes, are cholesterol-rich nanodomains that regulate many protein activities and cellular processes. Understanding the formation of the lipid-raft nanodomains helps us elucidate many complex interactions in the cell. In this study, the formation of lipid-raft nanodomains in a ternary palmitoyl-oleoyl-phosphatidylcholine/stearoyl-sphingomyelin/cholesterol (POPC/DPSM/Chol) lipid mixture, the most realistic surrogate model for biological membranes, has been successfully observed for the first time in-silico using microsecond timescale molecular dynamics simulations. The model reveals the formation of cholesterol-induced nanodomains with raft-like characteristics and their underlying mechanism: the cholesterol molecules segregate themselves into cholesterol nanodomains and then enrich the cholesterol-rich domain with sphingomyelin molecules to form a lipid raft thanks to the weak bonding of cholesterol with sphingomyelin. Besides, it is found that the increase in cholesterol concentration enhances the biophysical properties (e.g., bilayer thickness, area per lipid headgroup, and order parameter) of the lipid raft nanodomains. Such findings suggest that the POPC/DPSM/Chol bilayer is a suitable model to fundamentally extend the nanodomain evolution to investigate their lifetime and kinetics as well as to study protein-lipid interaction, protein-protein interaction, and selection of therapeutic molecules in the presence of lipid rafts.
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Affiliation(s)
- Tho H Ho
- Vietnam National University, Ho Chi Minh, Vietnam; Chemical Engineering Department, School of Biotechnology, International University, Quarter 6, Linh Trung Ward, Thu Duc City, Ho Chi Minh City 700000, Vietnam
| | - Trang T Nguyen
- Vietnam National University, Ho Chi Minh, Vietnam; Chemical Engineering Department, School of Biotechnology, International University, Quarter 6, Linh Trung Ward, Thu Duc City, Ho Chi Minh City 700000, Vietnam.
| | - Lam K Huynh
- Vietnam National University, Ho Chi Minh, Vietnam; Chemical Engineering Department, School of Biotechnology, International University, Quarter 6, Linh Trung Ward, Thu Duc City, Ho Chi Minh City 700000, Vietnam.
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11
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Polyvinyl Chloride Nanoparticles Affect Cell Membrane Integrity by Disturbing the Properties of the Multicomponent Lipid Bilayer in Arabidopsis thaliana. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27185906. [PMID: 36144641 PMCID: PMC9503312 DOI: 10.3390/molecules27185906] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 09/03/2022] [Accepted: 09/09/2022] [Indexed: 11/16/2022]
Abstract
The ubiquitous presence of nanoplastics (NPs) in natural ecosystems is a serious concern, as NPs are believed to threaten every life form on Earth. Micro- and nanoplastics enter living systems through multiple channels. Cell membranes function as the first barrier of entry to NPs, thus playing an important biological role. However, in-depth studies on the interactions of NPs with cell membranes have not been performed, and effective theoretical models of the underlying molecular details and physicochemical behaviors are lacking. In the present study, we investigated the uptake of polyvinyl chloride (PVC) nanoparticles by Arabidopsis thaliana root cells, which leads to cell membrane leakage and damage to membrane integrity. We performed all-atom molecular dynamics simulations to determine the effects of PVC NPs on the properties of the multicomponent lipid bilayer. These simulations revealed that PVCs easily permeate into model lipid membranes, resulting in significant changes to the membrane, including reduced density and changes in fluidity and membrane thickness. Our exploration of the interaction mechanisms between NPs and the cell membrane provided valuable insights into the effects of NPs on membrane structure and integrity.
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12
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MacDermott-Opeskin HI, Panizza A, Eijkelkamp BA, O'Mara ML. Dynamics of the Acinetobacter baumannii inner membrane under exogenous polyunsaturated fatty acid stress. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183908. [PMID: 35276227 DOI: 10.1016/j.bbamem.2022.183908] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 02/11/2022] [Accepted: 03/05/2022] [Indexed: 01/04/2023]
Abstract
Exogenous polyunsaturated fatty acids (PUFAs) are readily incorporated into the synthesis pathways of A. baumannii membrane phospholipids, where they contribute to reduced bacterial fitness and increased antimicrobial susceptibility. Here we examine the impact of PUFA membrane modification on membrane organisation and biophysical properties using coarse grained MARTINI simulations of chemically representative membrane models developed from mass-spectrometry datasets of an untreated, arachidonic acid (AA) treated and docosahexaenoic acid (DHA) treated A. baumannii membranes. Enzymatic integration of AA or DHA into phospholipids of the A. baumannii membrane resulted in modulation of membrane biophysical properties. Membrane thickness decreased slightly following PUFA treatment, concomitant with changes in the lateral area per lipid of each lipid headgroup class. PUFA treatment resulted in a decrease in membrane ordering and an increase in lipid lateral diffusion. Changes in lateral membrane organisation were observed in the PUFA treated membranes, with a concurrent increase in ordered cardiolipin domains and disordered PUFA-containing domains. Notably, separation between ordered and disordered domains was enhanced and was more pronounced for DHA relative to AA, providing a possible mechanism for greater antimicrobial action of DHA relative to AA observed experimentally. Furthermore, the membrane active antimicrobial, pentamidine, preferentially adsorbs to cardiolipin domains of the A. baumannii model membranes. This interaction, and membrane penetration of pentamidine, was enhanced following PUFA treatment. Cumulatively, this work explores the wide-ranging effects of PUFA incorporation on the A. baumannii membrane and provides a molecular basis for bacterial inner membrane disruption by PUFAs.
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Affiliation(s)
- Hugo I MacDermott-Opeskin
- Research School of Chemistry, College of Science, Australian National University, Canberra, ACT, 2601, Australia
| | - Alessandra Panizza
- Research School of Chemistry, College of Science, Australian National University, Canberra, ACT, 2601, Australia
| | - Bart A Eijkelkamp
- Molecular Science and Technology, College of Science and Engineering, Flinders University, Bedford Park, SA, 5042, Australia
| | - Megan L O'Mara
- Research School of Chemistry, College of Science, Australian National University, Canberra, ACT, 2601, Australia.
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13
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Kawamoto S, Liu H, Miyazaki Y, Seo S, Dixit M, DeVane R, MacDermaid C, Fiorin G, Klein ML, Shinoda W. SPICA Force Field for Proteins and Peptides. J Chem Theory Comput 2022; 18:3204-3217. [PMID: 35413197 DOI: 10.1021/acs.jctc.1c01207] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A coarse-grained (CG) model for peptides and proteins was developed as an extension of the Surface Property fItting Coarse grAined (SPICA) force field (FF). The model was designed to examine membrane proteins that are fully compatible with the lipid membranes of the SPICA FF. A preliminary version of this protein model was created using thermodynamic properties, including the surface tension and density in the SPICA (formerly called SDK) FF. In this study, we improved the CG protein model to facilitate molecular dynamics (MD) simulations with a reproduction of multiple properties from both experiments and all-atom (AA) simulations. An elastic network model was adopted to maintain the secondary structure within a single chain. The side-chain analogues reproduced the transfer free energy profiles across the lipid membrane and demonstrated reasonable association free energy (potential of mean force) in water compared to those from AA MD. A series of peptides/proteins adsorbed onto or penetrated into the membrane simulated by the CG MD correctly predicted the penetration depths and tilt angles of peripheral and transmembrane peptides/proteins as comparable to those in the orientations of proteins in membranes (OPM) database. In addition, the dimerization free energies of several transmembrane helices within a lipid bilayer were comparable to those from experimental estimation. Application studies on a series of membrane protein assemblies, scramblases, and poliovirus capsids demonstrated the good performance of the SPICA FF.
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Affiliation(s)
- Shuhei Kawamoto
- Department of Materials Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Huihui Liu
- Department of Materials Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Yusuke Miyazaki
- Department of Materials Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.,Research Institute for Interdisciplinary Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Sangjae Seo
- Department of Materials Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.,Korea Institute of Science and Technology Information, 245 Daehak-ro, Daejeon 34141, Republic of Korea
| | - Mayank Dixit
- Department of Materials Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Russell DeVane
- Modeling & Simulation, Corporate Research & Development, The Procter and Gamble Company, West Chester, Ohio 45069, United States
| | - Christopher MacDermaid
- Institute for Computational Molecular Science, Temple University, 1925 North 12th Street, Philadelphia, Pennsylvania 19122, United States
| | - Giacomo Fiorin
- Institute for Computational Molecular Science, Temple University, 1925 North 12th Street, Philadelphia, Pennsylvania 19122, United States
| | - Michael L Klein
- Institute for Computational Molecular Science, Temple University, 1925 North 12th Street, Philadelphia, Pennsylvania 19122, United States
| | - Wataru Shinoda
- Department of Materials Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.,Research Institute for Interdisciplinary Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.,Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
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14
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Sunidhi S, Sacher S, Atul, Garg P, Ray A. Elucidating the Structural Features of ABCA1 in its Heterogeneous Membrane Environment. Front Mol Biosci 2022; 8:803078. [PMID: 35155567 PMCID: PMC8830745 DOI: 10.3389/fmolb.2021.803078] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 12/30/2021] [Indexed: 11/17/2022] Open
Abstract
ATP Binding Cassette Transporter A1 (ABCA1) plays an integral part in Reverse Cholesterol Transport (RCT) and is critical for maintaining lipid homeostasis. One theory of lipid efflux by the transporter (alternating access) proposes that ABCA1 harbours two different conformations that provide alternating access for lipid binding and release. This is followed by sequestration via a direct interaction between ABCA1 and its partner, ApoA1. The other theory (lateral access) proposes that ABCA1 obtains lipids laterally from the membrane to form a temporary extracellular “reservoir”. This reservoir contains an isolated lipid monolayer due to the net accumulation of lipids in the exofacial leaflet. Recently, a full-length Cryo-EM structure of this 2,261-residue transmembrane protein showed its discreetly folded domains and have detected the presence of a tunnel enclosed within the extracellular domains (ECDs) but not in the TMDs, giving it an outward-facing conformation. This structure was hypothesized to substantiate the lateral access theory. Utilizing long time-scale multiple replica atomistic molecular dynamics simulations (MDS), we simulated the structure in a large heterogeneous lipid environment and found that the protein undergoes several large conformational changes in its extremities. We observed that the cavity enclosed within ATP unbound form of ABCA1 is narrow at the distal ends of TMD as well as the ECD region substantiating the “lateral access” theory. We have also characterized ABCA1 and the lipid dynamics along with the protein-lipid interactions in the heterogeneous environment, providing novel insights into understanding ABCA1 conformation at an atomistic level.
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15
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Hitaishi P, Mandal P, Ghosh SK. Partitioning of a Hybrid Lipid in Domains of Saturated and Unsaturated Lipids in a Model Cellular Membrane. ACS OMEGA 2021; 6:34546-34554. [PMID: 34963939 PMCID: PMC8697375 DOI: 10.1021/acsomega.1c04835] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 11/30/2021] [Indexed: 06/14/2023]
Abstract
The cellular membranes are composed of hundreds of components such as lipids, proteins, and sterols that are chemically and physically distinct from each other. The lipid-lipid and lipid-protein interactions form domains in this membrane, which play vital roles in membrane physiology. The hybrid lipids (HLs) with one saturated and one unsaturated chain can control the shape and size of these domains, ensuring the thermodynamic stability of a membrane. In this study, the thermodynamics of mixing of a HL and its structural effects on the phase separated domains in a model membrane composed of a saturated and an unsaturated lipid have been investigated. The HL is observed to mix into an unsaturated lipid reducing the Gibbs free energy, whereas the mixing is unfavorable in a saturated lipid. The presence of an HL in an unsaturated lipid tends to increase its area fraction, which is reflected in the enhanced correlation length across the bilayers in a multilayered sample. There is a feeble effect on the domain structure of the saturated lipid due to the presence of the HLs at the phase boundary. This study concludes that the HLs preferentially participate in the unsaturated lipid regions compared to that of a saturated lipid.
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16
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Trofimenko E, Grasso G, Heulot M, Chevalier N, Deriu MA, Dubuis G, Arribat Y, Serulla M, Michel S, Vantomme G, Ory F, Dam LC, Puyal J, Amati F, Lüthi A, Danani A, Widmann C. Genetic, cellular, and structural characterization of the membrane potential-dependent cell-penetrating peptide translocation pore. eLife 2021; 10:69832. [PMID: 34713805 PMCID: PMC8639150 DOI: 10.7554/elife.69832] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 10/28/2021] [Indexed: 12/11/2022] Open
Abstract
Cell-penetrating peptides (CPPs) allow intracellular delivery of bioactive cargo molecules. The mechanisms allowing CPPs to enter cells are ill-defined. Using a CRISPR/Cas9-based screening, we discovered that KCNQ5, KCNN4, and KCNK5 potassium channels positively modulate cationic CPP direct translocation into cells by decreasing the transmembrane potential (Vm). These findings provide the first unbiased genetic validation of the role of Vm in CPP translocation in cells. In silico modeling and live cell experiments indicate that CPPs, by bringing positive charges on the outer surface of the plasma membrane, decrease the Vm to very low values (–150 mV or less), a situation we have coined megapolarization that then triggers formation of water pores used by CPPs to enter cells. Megapolarization lowers the free energy barrier associated with CPP membrane translocation. Using dyes of varying dimensions in CPP co-entry experiments, the diameter of the water pores in living cells was estimated to be 2 (–5) nm, in accordance with the structural characteristics of the pores predicted by in silico modeling. Pharmacological manipulation to lower transmembrane potential boosted CPP cellular internalization in zebrafish and mouse models. Besides identifying the first proteins that regulate CPP translocation, this work characterized key mechanistic steps used by CPPs to cross cellular membranes. This opens the ground for strategies aimed at improving the ability of cells to capture CPP-linked cargos in vitro and in vivo. Before a drug can have its desired effect, it must reach its target tissue or organ, and enter its cells. This is not easy because cells are surrounded by the plasma membrane, a fat-based barrier that separates the cell from its external environment. The plasma membrane contains proteins that act as channels, shuttling specific molecules in and out of the cell, and it also holds charge, with its inside surface being more negatively charged than its outside surface. Cell-penetrating peptides are short sequences of amino acids (the building blocks that form proteins) that carry positive charges. These positive charges allow them to cross the membrane easily, but it is not well understood how. To find out how cell-penetrating peptides cross the membrane, Trofimenko et al. attached them to dyes of different sizes. This revealed that the cell-penetrating peptides enter the cell through temporary holes called water pores, which measure about two nanometres across. The water pores form when the membrane becomes ‘megapolarized’, this is, when the difference in charge between the inside and the outside of the membrane becomes greater than normal. This can happen when the negative charge on the inside surface or the positive charge on the outer surface of the membrane increase. Megapolarization depends on potassium channels, which transport positive potassium ions outside the cell, making the outside of the membrane positive. When cell-penetrating peptides arrive at the outer surface of the cell near potassium channels, they make it even more positive. This increases the charge difference between the inside and the outside of the cell, allowing water pores to form. Once the peptides pass through the pores, the charge difference between the inside and the outside of the cell membrane dissipates, and the pores collapse. Drug developers are experimenting with attaching cell-penetrating peptides to drugs to help them get inside their target cells. Currently there are several experimental medications of this kind in clinical trials. Understanding how these peptides gain entry, and what size of molecule they could carry with them, provides solid ground for further drug development.
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Affiliation(s)
- Evgeniya Trofimenko
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Gianvito Grasso
- Dalle Molle Institute for Artificial Intelligence Research, Università della Svizzera italiana, Scuola Universitaria Professionale della Svizzera Italiana, Lugano, Switzerland
| | - Mathieu Heulot
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Nadja Chevalier
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Marco A Deriu
- PolitoBIOMed Lab Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Torino, Italy
| | - Gilles Dubuis
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Yoan Arribat
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Marc Serulla
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Sebastien Michel
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Gil Vantomme
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Florine Ory
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Linh Chi Dam
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Julien Puyal
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.,CURML (University Center of Legal Medicine), Lausanne University Hospital, Lausanne, Switzerland
| | - Francesca Amati
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Anita Lüthi
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Andrea Danani
- Dalle Molle Institute for Artificial Intelligence Research, Università della Svizzera italiana, Scuola Universitaria Professionale della Svizzera Italiana, Lugano, Switzerland
| | - Christian Widmann
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
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17
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Plant Sterol Clustering Correlates with Membrane Microdomains as Revealed by Optical and Computational Microscopy. MEMBRANES 2021; 11:membranes11100747. [PMID: 34677513 PMCID: PMC8539253 DOI: 10.3390/membranes11100747] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/22/2021] [Accepted: 09/27/2021] [Indexed: 11/26/2022]
Abstract
Local inhomogeneities in lipid composition play a crucial role in the regulation of signal transduction and membrane traffic. This is particularly the case for plant plasma membrane, which is enriched in specific lipids, such as free and conjugated forms of phytosterols and typical phytosphingolipids. Nevertheless, most evidence for microdomains in cells remains indirect, and the nature of membrane inhomogeneities has been difficult to characterize. We used a new push–pull pyrene probe and fluorescence lifetime imaging microscopy (FLIM) combined with all-atom multiscale molecular dynamics simulations to provide a detailed view on the interaction between phospholipids and phytosterol and the effect of modulating cellular phytosterols on membrane-associated microdomains and phase separation formation. Our understanding of the organization principles of biomembranes is limited mainly by the challenge to measure distributions and interactions of lipids and proteins within the complex environment of living cells. Comparing phospholipids/phytosterol compositions typical of liquid-disordered (Ld) and liquid-ordered (Lo) domains, we furthermore show that phytosterols play crucial roles in membrane homeostasis. The simulation work highlights how state-of-the-art modeling alleviates some of the prior concerns and how unrefuted discoveries can be made through a computational microscope. Altogether, our results support the role of phytosterols in the lateral structuring of the PM of plant cells and suggest that they are key compounds for the formation of plant PM microdomains and the lipid-ordered phase.
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18
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Talandashti R, Mehrnejad F, Rostamipour K, Doustdar F, Lavasanifar A. Molecular Insights into Pore Formation Mechanism, Membrane Perturbation, and Water Permeation by the Antimicrobial Peptide Pleurocidin: A Combined All-Atom and Coarse-Grained Molecular Dynamics Simulation Study. J Phys Chem B 2021; 125:7163-7176. [PMID: 34171196 DOI: 10.1021/acs.jpcb.1c01954] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The antimicrobial peptide (AMP) pleurocidin has a broad antimicrobial activity against Gram-negative and Gram-positive bacteria by perturbation and permeabilizing their membranes; however, understanding the mechanism of action of pleurocidin, a promising AMP for replacing current antibiotic agents, has tremendous importance for future applications. Hence, we applied all-atom (AA) and coarse-grained (CG) molecular dynamics (MD) simulations to provide molecular-level insights into the pore-forming process. The early stages of pore formation were examined by 500 ns AA simulations. The results demonstrated that pleurocidin has the ability to create a pore with two peptides through which water molecules can flow. However, the results of the 25 μs CG simulations indicate that the final pore will be created by accumulation of more than two peptides. The results show that after 2.5 μs of simulations, peptides will aggregate and create a channel-like pore across the membrane. Pleurocidin can construct a more efficient and stable pore in the anionic membranes than in the zwitterionic membranes. Moreover, the structure amphipathicity, polarity, and basic residues play crucial roles in the pore formation and flow of water molecules across the lipid bilayers. In general, the findings revealed that based on the lipid compositions of the membranes, pleurocidin could act by forming either toroidal or disordered toroidal pores with different peptide arrangements.
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Affiliation(s)
- Reza Talandashti
- Infectious Diseases and Tropical Medicine Research Center, Shahid Beheshti University of Medical Sciences, P. O. Box: 1985717443 Tehran, Iran.,Department of Life Sciences Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran 14395-1561, Iran
| | - Faramarz Mehrnejad
- Department of Life Sciences Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran 14395-1561, Iran
| | - Kiana Rostamipour
- Department of Life Sciences Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran 14395-1561, Iran
| | - Farahnoosh Doustdar
- Department of Life Sciences Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran 14395-1561, Iran.,Department of Microbiology, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran 19839-63113, Iran
| | - Afsaneh Lavasanifar
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
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19
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Kjølbye LR, De Maria L, Wassenaar TA, Abdizadeh H, Marrink SJ, Ferkinghoff-Borg J, Schiøtt B. General Protocol for Constructing Molecular Models of Nanodiscs. J Chem Inf Model 2021; 61:2869-2883. [PMID: 34048229 DOI: 10.1021/acs.jcim.1c00157] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nanodisc technology is increasingly being applied for structural and biophysical studies of membrane proteins. In this work, we present a general protocol for constructing molecular models of nanodiscs for molecular dynamics simulations. The protocol is written in python and based on geometric equations, making it fast and easy to modify, enabling automation and customization of nanodiscs in silico. The novelty being the ability to construct any membrane scaffold protein (MSP) variant fast and easy given only an input sequence. We validated and tested the protocol by simulating seven different nanodiscs of various sizes and with different membrane scaffold proteins, both circularized and noncircularized. The structural and biophysical properties were analyzed and shown to be in good agreement with previously reported experimental data and simulation studies.
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Affiliation(s)
- Lisbeth R Kjølbye
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark.,Novo Nordisk A/S, Novo Nordisk Park 1, 2760 Måløv, Denmark
| | | | - Tsjerk A Wassenaar
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Haleh Abdizadeh
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | | | - Birgit Schiøtt
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark.,Interdisciplinary Nanoscience Center, Aarhus University, Gustav Wieds vej 14, 8000 Aarhus C, Denmark
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20
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van den Broek K, Epple M, Kersten LS, Kuhn H, Zielesny A. Quantitative Estimation of Cyclotide-Induced Bilayer Membrane Disruption by Lipid Extraction with Mesoscopic Simulation. J Chem Inf Model 2021; 61:3027-3040. [PMID: 34008405 DOI: 10.1021/acs.jcim.1c00332] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cyclotide-induced membrane disruption is studied at the microsecond timescale by dissipative particle dynamics to quantitatively estimate a kinetic rate constant for membrane lipid extraction with a ″sandwich″ interaction model where two bilayer membranes enclose a cyclotide/water compartment. The obtained bioactivity trends for cyclotides Kalata B1, Cycloviolacin O2, and selected mutants with different membrane types are in agreement with experimental findings: For all membranes investigated, Cycloviolacin O2 shows a higher lipid extraction activity than Kalata B1. The presence of cholesterol leads to a decreased cyclotide activity compared to cholesterol-free membranes. Phosphoethanolamine-rich membranes exhibit an increased membrane disruption. A cyclotide's ″hydrophobic patch″ surface area is important for its bioactivity. A replacement of or with charged amino acid residues may lead to super-mutants with above-native activity but without simple charge-activity patterns. Cyclotide mixtures show linearly additive bioactivities without significant sub- or over-additive effects. The proposed method can be applied as a fast and easy-to-use tool for exploring structure-activity relationships of cyclotide/membrane systems: With the open software provided, the rate constant of a single cyclotide/membrane system can be determined in about 1 day by a scientific end-user without programming skills.
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Affiliation(s)
- Karina van den Broek
- Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, 45141 Essen, Germany.,Institute for Bioinformatics and Chemoinformatics, Westphalian University of Applied Sciences, 45665 Recklinghausen, Germany
| | - Matthias Epple
- Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, 45141 Essen, Germany
| | - Lisa Sophie Kersten
- Institute for Bioinformatics and Chemoinformatics, Westphalian University of Applied Sciences, 45665 Recklinghausen, Germany
| | - Hubert Kuhn
- CAM-D Technologies GmbH, 42697 Solingen, Germany
| | - Achim Zielesny
- Institute for Bioinformatics and Chemoinformatics, Westphalian University of Applied Sciences, 45665 Recklinghausen, Germany
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21
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The antibiotic darobactin mimics a β-strand to inhibit outer membrane insertase. Nature 2021; 593:125-129. [PMID: 33854236 DOI: 10.1038/s41586-021-03455-w] [Citation(s) in RCA: 114] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 03/15/2021] [Indexed: 02/02/2023]
Abstract
Antibiotics that target Gram-negative bacteria in new ways are needed to resolve the antimicrobial resistance crisis1-3. Gram-negative bacteria are protected by an additional outer membrane, rendering proteins on the cell surface attractive drug targets4,5. The natural compound darobactin targets the bacterial insertase BamA6-the central unit of the essential BAM complex, which facilitates the folding and insertion of outer membrane proteins7-13. BamA lacks a typical catalytic centre, and it is not obvious how a small molecule such as darobactin might inhibit its function. Here we resolve the mode of action of darobactin at the atomic level using a combination of cryo-electron microscopy, X-ray crystallography, native mass spectrometry, in vivo experiments and molecular dynamics simulations. Two cyclizations pre-organize the darobactin peptide in a rigid β-strand conformation. This creates a mimic of the recognition signal of native substrates with a superior ability to bind to the lateral gate of BamA. Upon binding, darobactin replaces a lipid molecule from the lateral gate to use the membrane environment as an extended binding pocket. Because the interaction between darobactin and BamA is largely mediated by backbone contacts, it is particularly robust against potential resistance mutations. Our results identify the lateral gate as a functional hotspot in BamA and will allow the rational design of antibiotics that target this bacterial Achilles heel.
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22
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Lamprakis C, Andreadelis I, Manchester J, Velez-Vega C, Duca JS, Cournia Z. Evaluating the Efficiency of the Martini Force Field to Study Protein Dimerization in Aqueous and Membrane Environments. J Chem Theory Comput 2021; 17:3088-3102. [PMID: 33913726 DOI: 10.1021/acs.jctc.0c00507] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Protein-protein complex assembly is one of the major drivers of biological response. Understanding the mechanisms of protein oligomerization/dimerization would allow one to elucidate how these complexes participate in biological activities and could ultimately lead to new approaches in designing novel therapeutic agents. However, determining the exact association pathways and structures of such complexes remains a challenge. Here, we use parallel tempering metadynamics simulations in the well-tempered ensemble to evaluate the performance of Martini 2.2P and Martini open-beta 3 (Martini 3) force fields in reproducing the structure and energetics of the dimerization process of membrane proteins and proteins in an aqueous solution in reasonable accuracy and throughput. We find that Martini 2.2P systematically overestimates the free energy of association by estimating large barriers in distinct areas, which likely leads to overaggregation when multiple monomers are present. In comparison, the less viscous Martini 3 results in a systematic underestimation of the free energy of association for proteins in solution, while it performs well in describing the association of membrane proteins. In all cases, the near-native dimer complexes are identified as minima in the free energy surface albeit not always as the lowest minima. In the case of Martini 3, we find that the spurious supramolecular protein aggregation present in Martini 2.2P multimer simulations is alleviated and thus this force field may be more suitable for the study of protein oligomerization. We propose that the use of enhanced sampling simulations with a refined coarse-grained force field and appropriately defined collective variables is a robust approach for studying the protein dimerization process, although one should be cautious of the ranking of energy minima.
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Affiliation(s)
- Christos Lamprakis
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece
| | - Ioannis Andreadelis
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece
| | - John Manchester
- Computer-Aided Drug Discovery, Global Discovery Chemistry, Novartis Institutes for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Camilo Velez-Vega
- Computer-Aided Drug Discovery, Global Discovery Chemistry, Novartis Institutes for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - José S Duca
- Computer-Aided Drug Discovery, Global Discovery Chemistry, Novartis Institutes for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Zoe Cournia
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece
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23
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Souza PCT, Limongelli V, Wu S, Marrink SJ, Monticelli L. Perspectives on High-Throughput Ligand/Protein Docking With Martini MD Simulations. Front Mol Biosci 2021; 8:657222. [PMID: 33855050 PMCID: PMC8039319 DOI: 10.3389/fmolb.2021.657222] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 03/05/2021] [Indexed: 01/12/2023] Open
Abstract
Molecular docking is central to rational drug design. Current docking techniques suffer, however, from limitations in protein flexibility and solvation models and by the use of simplified scoring functions. All-atom molecular dynamics simulations, on the other hand, feature a realistic representation of protein flexibility and solvent, but require knowledge of the binding site. Recently we showed that coarse-grained molecular dynamics simulations, based on the most recent version of the Martini force field, can be used to predict protein/ligand binding sites and pathways, without requiring any a priori information, and offer a level of accuracy approaching all-atom simulations. Given the excellent computational efficiency of Martini, this opens the way to high-throughput drug screening based on dynamic docking pipelines. In this opinion article, we sketch the roadmap to achieve this goal.
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Affiliation(s)
- Paulo C. T. Souza
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
- PharmCADD, Busan, South Korea
- Molecular Microbiology and Structural Biochemistry (MMSB, UMR 5086), CNRS, University of Lyon, Lyon, France
| | - Vittorio Limongelli
- Faculty of Biomedical Sciences, Institute of Computational Science, Università della Svizzera Italiana (USI), Lugano, Switzerland
- Department of Pharmacy, University of Naples “Federico II”, Naples, Italy
| | - Sangwook Wu
- PharmCADD, Busan, South Korea
- Department of Physics, Pukyong National University, Busan, South Korea
| | - Siewert J. Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Luca Monticelli
- Molecular Microbiology and Structural Biochemistry (MMSB, UMR 5086), CNRS, University of Lyon, Lyon, France
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24
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Wilson KA, Wang L, Lin YC, O'Mara ML. Investigating the lipid fingerprint of SLC6 neurotransmitter transporters: a comparison of dDAT, hDAT, hSERT, and GlyT2. BBA ADVANCES 2021; 1:100010. [PMID: 37082011 PMCID: PMC10074915 DOI: 10.1016/j.bbadva.2021.100010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The local lipid annulus, or "fingerprint", of four SLC6 transporters (dDAT, hDAT, hSERT, and GlyT2) embedded in a complex neuronal membrane were compared and characterised using molecular dynamics. Our analysis included the development of new tools to improve membrane leaflet detection and the analysis of leaflet-dependent properties. Overall, the lipid fingerprints of the four transporters are comprised of similar lipids when grouped by headgroup or tail saturation. The enrichment and depletion of specific lipids, including sites of cholesterol contacts, varies between transporters. The subtle differences in lipid fingerprints results in varying membrane biophysical properties near the transporter. Our results highlight that the lipid-fingerprint of SLC6 transporters in complex membranes is highly dependent on membrane composition. Our results further characterize how the presence and identity of membrane proteins affects the complex interplay of lipid-protein interactions, influencing the local lipid environment and membrane biophysical properties.
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25
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Yano Y, Watanabe Y, Matsuzaki K. Thermodynamic and kinetic stabilities of transmembrane helix bundles as revealed by single-pair FRET analysis: Effects of the number of membrane-spanning segments and cholesterol. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1863:183532. [PMID: 33316240 DOI: 10.1016/j.bbamem.2020.183532] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/02/2020] [Accepted: 12/07/2020] [Indexed: 12/23/2022]
Abstract
The tertiary structures and conformational dynamics of transmembrane (TM) helical proteins are maintained by the interhelical interaction network in membranes, although it is complicated to analyze the underlying driving forces because the amino acid sequences can involve multiple and various types of interactions. To obtain insights into basal and common effects of the number of membrane-spanning segments and membrane cholesterol, we measured stabilities of helix bundles composed of simple TM helices (AALALAA)3 (1TM) and (AALALAA)3-G5-(AALALAA)3 (2TM). Association-dissociation dynamics for 1TM-1TM, 1TM-2TM, and 2TM-2TM pairs were monitored to compare stabilities of 2-, 3-, and 4-helical bundles, respectively, with single-pair fluorescence resonance energy transfer (sp-FRET) in liposome membranes. Both thermodynamic and kinetic stabilities of the helix bundles increased with a greater number of membrane-spanning segments in POPC. The presence of 30 mol% cholesterol strongly enhanced the formation of 1TM-1TM and 1TM-2TM bundles (~ - 9 kJ mol-1), whereas it only weakly stabilized the 2TM-2TM bundle (~ - 3 kJ mol-1). Fourier transform infrared-polarized attenuated total reflection (ATR-FTIR) spectroscopy revealed an ~30° tilt of the helix axis relative to bilayer normal for the 1TM-2TM pair in the presence of cholesterol, suggesting the formation of a tilted helix bundle to release high lateral pressure at the center of cholesterol-containing membranes. These results demonstrate that the number of membrane-spanning segments affects the stability and structure of the helix bundle, and their cholesterol-dependences. Such information is useful to understand the basics of folding and assembly of multispanning TM proteins.
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Affiliation(s)
- Yoshiaki Yano
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yuta Watanabe
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Katsumi Matsuzaki
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
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26
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Complexity of seemingly simple lipid nanodiscs. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183420. [DOI: 10.1016/j.bbamem.2020.183420] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 06/26/2020] [Accepted: 07/07/2020] [Indexed: 12/15/2022]
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27
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Sun D, Peyear TA, Bennett WFD, Holcomb M, He S, Zhu F, Lightstone FC, Andersen OS, Ingólfsson HI. Assessing the Perturbing Effects of Drugs on Lipid Bilayers Using Gramicidin Channel-Based In Silico and In Vitro Assays. J Med Chem 2020; 63:11809-11818. [PMID: 32945672 PMCID: PMC7586341 DOI: 10.1021/acs.jmedchem.0c00958] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Indexed: 01/07/2023]
Abstract
Partitioning of bioactive molecules, including drugs, into cell membranes may produce indiscriminate changes in membrane protein function. As a guide to safe drug development, it therefore becomes important to be able to predict the bilayer-perturbing potency of hydrophobic/amphiphilic drugs candidates. Toward this end, we exploited gramicidin channels as molecular force probes and developed in silico and in vitro assays to measure drugs' bilayer-modifying potency. We examined eight drug-like molecules that were found to enhance or suppress gramicidin channel function in a thick 1,2-dierucoyl-sn-glycero-3-phosphocholine (DC22:1PC) but not in thin 1,2-dioleoyl-sn-glycero-3-phosphocholine (DC18:1PC) lipid bilayer. The mechanism underlying this difference was attributable to the changes in gramicidin dimerization free energy by drug-induced perturbations of lipid bilayer physical properties and bilayer-gramicidin interactions. The combined in silico and in vitro approaches, which allow for predicting the perturbing effects of drug candidates on membrane protein function, have implications for preclinical drug safety assessment.
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Affiliation(s)
- Delin Sun
- Biosciences
and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Thasin A. Peyear
- Department
of Physiology and Biophysics, Weill Cornell
Medicine, New York, New York 10065, United States
| | - W. F. Drew Bennett
- Biosciences
and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Matthew Holcomb
- Biosciences
and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Stewart He
- Biosciences
and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Fangqiang Zhu
- Biosciences
and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Felice C. Lightstone
- Biosciences
and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Olaf S. Andersen
- Department
of Physiology and Biophysics, Weill Cornell
Medicine, New York, New York 10065, United States
| | - Helgi I. Ingólfsson
- Biosciences
and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
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28
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Buyan A, Cox CD, Barnoud J, Li J, Chan HSM, Martinac B, Marrink SJ, Corry B. Piezo1 Forms Specific, Functionally Important Interactions with Phosphoinositides and Cholesterol. Biophys J 2020; 119:1683-1697. [PMID: 32949489 PMCID: PMC7642233 DOI: 10.1016/j.bpj.2020.07.043] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/06/2020] [Accepted: 07/15/2020] [Indexed: 10/25/2022] Open
Abstract
Touch, hearing, and blood pressure regulation require mechanically gated ion channels that convert mechanical stimuli into electrical currents. One such channel is Piezo1, which plays a key role in the transduction of mechanical stimuli in humans and is implicated in diseases, such as xerocytosis and lymphatic dysplasia. There is building evidence that suggests Piezo1 can be regulated by the membrane environment, with the activity of the channel determined by the local concentration of lipids, such as cholesterol and phosphoinositides. To better understand the interaction of Piezo1 with its environment, we conduct simulations of the protein in a complex mammalian bilayer containing more than 60 different lipid types together with electrophysiology and mutagenesis experiments. We find that the protein alters its local membrane composition, enriching specific lipids and forming essential binding sites for phosphoinositides and cholesterol that are functionally relevant and often related to Piezo1-mediated pathologies. We also identify a number of key structural connections between the propeller and pore domains located close to lipid-binding sites.
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Affiliation(s)
- Amanda Buyan
- Research School of Biology, Australian National University, Acton, Canberra, Australia
| | - Charles D Cox
- Victor Chang Cardiac Research Institute, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales, Australia.
| | - Jonathan Barnoud
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania; Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Jinyuan Li
- Victor Chang Cardiac Research Institute, New South Wales, Australia
| | - Hannah S M Chan
- Research School of Biology, Australian National University, Acton, Canberra, Australia
| | - Boris Martinac
- Victor Chang Cardiac Research Institute, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales, Australia
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Ben Corry
- Research School of Biology, Australian National University, Acton, Canberra, Australia.
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29
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Triacylglycerols sequester monotopic membrane proteins to lipid droplets. Nat Commun 2020; 11:3944. [PMID: 32769983 PMCID: PMC7414839 DOI: 10.1038/s41467-020-17585-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 07/08/2020] [Indexed: 01/05/2023] Open
Abstract
Triacylglycerols (TG) are synthesized at the endoplasmic reticulum (ER) bilayer and packaged into organelles called lipid droplets (LDs). LDs are covered by a single phospholipid monolayer contiguous with the ER bilayer. This connection is used by several monotopic integral membrane proteins, with hydrophobic membrane association domains (HDs), to diffuse between the organelles. However, how proteins partition between ER and LDs is not understood. Here, we employed synthetic model systems and found that HD-containing proteins strongly prefer monolayers and returning to the bilayer is unfavorable. This preference for monolayers is due to a higher affinity of HDs for TG over membrane phospholipids. Protein distribution is regulated by PC/PE ratio via alterations in monolayer packing and HD-TG interaction. Thus, HD-containing proteins appear to non-specifically accumulate to the LD surface. In cells, protein editing mechanisms at the ER membrane would be necessary to prevent unspecific relocation of HD-containing proteins to LDs. Triacylglycerols (TG) are synthesized at the endoplasmic reticulum (ER) bilayer and packaged into monolayer lipid droplets (LDs), but how proteins partition between ER and LDs is poorly understood. Here authors use synthetic model systems and find that proteins containing hydrophobic membrane association domains strongly prefer monolayers and that returning to the bilayer is unfavorable.
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30
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Krah A, Marzinek JK, Bond PJ. Characterizing the Hydration Properties of Proton Binding Sites in the ATP Synthase c-Rings of Bacillus Species. J Phys Chem B 2020; 124:7176-7183. [PMID: 32687713 DOI: 10.1021/acs.jpcb.0c03896] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The membrane-embedded domain of ATP synthases contains the c-ring, which translocates ions across the membrane, and its resultant rotation is coupled to ATP synthesis in the extramembranous domain. During rotation, the c-ring becomes accessible on both sides of the lipid bilayer to solvent via channels connected to the other membrane-embedded component, the a subunit, and thereby allows the ion to be released into the solvent environment. In recent times, many experimental structures of c-rings from different species have been solved. In some of these, a water molecule with a proposed "structural role" has been identified within the c-ring ion binding site, but in general, the requirement for high resolution to resolve specific water densities complicates their interpretation. In the present study, we use molecular dynamics (MD) simulations and rigorous free energy calculations to characterize the dynamics and energetics of a water molecule within the ion binding site of the c-ring from Bacillus pseudofirmus OF4, in its wild type (WT) and P51A mutant forms, along with the c-ring from thermophilic Bacillus PS3. Our data suggest that a water molecule stably binds to the P51A mutant, as well as helping to identify a bound water molecule in Bacillus PS3 whose presence was previously overlooked due to the limited resolution of the structural data. Sequence analysis further identifies a novel conserved sequence motif that is likely required to harbor a water molecule for stable ion coordination in the binding site of such proteins.
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Affiliation(s)
- Alexander Krah
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671
| | - Jan K Marzinek
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671
| | - Peter J Bond
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671.,Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543
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31
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Favarin BZ, Bolean M, Ramos AP, Magrini A, Rosato N, Millán JL, Bottini M, Costa-Filho AJ, Ciancaglini P. Lipid composition modulates ATP hydrolysis and calcium phosphate mineral propagation by TNAP-harboring proteoliposomes. Arch Biochem Biophys 2020; 691:108482. [PMID: 32710882 DOI: 10.1016/j.abb.2020.108482] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/09/2020] [Accepted: 06/22/2020] [Indexed: 01/13/2023]
Abstract
Bone biomineralization is mediated by a special class of extracellular vesicles, named matrix vesicles (MVs), released by osteogenic cells. The MV membrane is enriched in sphingomyelin (SM), cholesterol (Chol) and tissue non-specific alkaline phosphatase (TNAP) compared with the parent cells' plasma membrane. TNAP is an ATP phosphohydrolase bound to cell and MV membranes via a glycosylphosphatidylinositol (GPI) anchor. Previous studies have shown that the lipid microenvironment influences the catalytic activity of enzymes incorporated into lipid bilayers. However, there is a lack of information about how the lipid microenvironment controls the ability of MV membrane-bound enzymes to induce mineral precipitation. Herein, we used TNAP-harboring proteoliposomes made of either pure dimyristoylphosphatidylcholine (DMPC) or DMPC mixed with either Chol, SM or both of them as MV biomimetic systems to evaluate how the composition modulates the lipid microenvironment and, in turn, TNAP incorporation into the lipid bilayer by means of calorimetry. These results were correlated with the proteoliposomes' catalytic activity and ability to induce the precipitation of amorphous calcium phosphate (ACP) in vitro. DMPC:SM proteoliposomes displayed the highest efficiency of mineral propagation, apparent affinity for ATP and substrate hydrolysis efficiency, which correlated with their highest degree of membrane organization (highest ΔH), among the tested proteoliposomes. Results obtained from turbidimetry and Fourier transformed infrared (FTIR) spectroscopy showed that the tested proteoliposomes induced ACP precipitation with the order DMPC:SM>DMPC:Chol:SM≈DMPC:Chol>DMPC which correlated with the lipid organization and the presence of SM in the proteoliposome membrane. Our study arises important insights regarding the physical properties and role of lipid organization in MV-mediated mineralization.
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Affiliation(s)
- B Z Favarin
- Department of Chemistry, FFCLRP, University of São Paulo, Ribeirão Preto, SP, Brazil; Department of Physics, FFCLRP, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - M Bolean
- Department of Chemistry, FFCLRP, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - A P Ramos
- Department of Chemistry, FFCLRP, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - A Magrini
- Department of Biopathology and Imaging Diagnostics, University of Rome Tor Vergata, Rome, Italy
| | - N Rosato
- Department of Experimental Medicine, University of Rome Tor Vergata, Rome, Italy
| | - J L Millán
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - M Bottini
- Department of Experimental Medicine, University of Rome Tor Vergata, Rome, Italy; Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
| | - A J Costa-Filho
- Department of Physics, FFCLRP, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - P Ciancaglini
- Department of Chemistry, FFCLRP, University of São Paulo, Ribeirão Preto, SP, Brazil.
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32
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Menon S, Sengupta N, Das P. Nanoscale Interplay of Membrane Composition and Amyloid Self-Assembly. J Phys Chem B 2020; 124:5837-5846. [DOI: 10.1021/acs.jpcb.0c03796] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Sneha Menon
- Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Neelanjana Sengupta
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India
| | - Payel Das
- IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, United States
- Applied Physics and Applied Math Department, Columbia University, New York, New York 10027, United States
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33
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Du D, Neuberger A, Orr MW, Newman CE, Hsu PC, Samsudin F, Szewczak-Harris A, Ramos LM, Debela M, Khalid S, Storz G, Luisi BF. Interactions of a Bacterial RND Transporter with a Transmembrane Small Protein in a Lipid Environment. Structure 2020; 28:625-634.e6. [PMID: 32348749 PMCID: PMC7267776 DOI: 10.1016/j.str.2020.03.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 02/14/2020] [Accepted: 03/27/2020] [Indexed: 12/01/2022]
Abstract
The small protein AcrZ in Escherichia coli interacts with the transmembrane portion of the multidrug efflux pump AcrB and increases resistance of the bacterium to a subset of the antibiotic substrates of that transporter. It is not clear how the physical association of the two proteins selectively changes activity of the pump for defined substrates. Here, we report cryo-EM structures of AcrB and the AcrBZ complex in lipid environments, and comparisons suggest that conformational changes occur in the drug-binding pocket as a result of AcrZ binding. Simulations indicate that cardiolipin preferentially interacts with the AcrBZ complex, due to increased contact surface, and we observe that chloramphenicol sensitivity of bacteria lacking AcrZ is exacerbated when combined with cardiolipin deficiency. Taken together, the data suggest that AcrZ and lipid cooperate to allosterically modulate AcrB activity. This mode of regulation by a small protein and lipid may occur for other membrane proteins.
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Affiliation(s)
- Dijun Du
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK.
| | - Arthur Neuberger
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
| | - Mona Wu Orr
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892-4417, USA
| | - Catherine E Newman
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
| | - Pin-Chia Hsu
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK
| | - Firdaus Samsudin
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK
| | - Andrzej Szewczak-Harris
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
| | - Leana M Ramos
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892-4417, USA
| | - Mekdes Debela
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK.
| | - Gisela Storz
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892-4417, USA.
| | - Ben F Luisi
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK.
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34
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Lavagna E, Barnoud J, Rossi G, Monticelli L. Size-dependent aggregation of hydrophobic nanoparticles in lipid membranes. NANOSCALE 2020; 12:9452-9461. [PMID: 32328605 DOI: 10.1039/d0nr00868k] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The aggregation of nanoparticles affects their reactivity, transport across biological membranes, uptake into cells, toxicity, and fate in the environment. In the case of membrane-embedded, hydrophobic nanoparticles the relationship between size and aggregation pattern is not well understood. Here, we explore this relationship for the case of spherically symmetrical nanoparticles using the MARTINI coarse-grained force field. We find that the free energy of dimerization depends strongly on nanoparticle size: the smallest molecules (mimicking C60 fullerene) aggregate only weakly, the largest ones form large three-dimensional aggregates causing major deformations in the host membrane, and the intermediate-sized particles show a tendency to form linear aggregates. Suppressing membrane undulations reduces very significantly aggregation, and substantially abolishes linear aggregation, suggesting a relationship between membrane curvature and aggregation geometry. At low concentration, when placed on membranes of variable curvature, the intermediate size nanoparticles move rapidly to high curvature regions - suggesting that they can sense membrane curvature. At high concentration, the same nanoparticles induce massive membrane deformations, without affecting the mechanical stability of the membrane - suggesting that they can generate membrane curvature.
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Affiliation(s)
- Enrico Lavagna
- Department of Physics, University of Genoa, Via Dodecaneso 33, 16146 Genoa, Italy.
| | - Jonathan Barnoud
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Giulia Rossi
- Department of Physics, University of Genoa, Via Dodecaneso 33, 16146 Genoa, Italy.
| | - Luca Monticelli
- Univ Lyon, CNRS, Molecular Microbiology and Structural Biochemistry (MMSB, UMR 5086), F-69007, Lyon, France.
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35
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Gopal SM, Pawar AB, Wassenaar TA, Sengupta D. Lipid-dependent conformational landscape of the ErbB2 growth factor receptor dimers. Chem Phys Lipids 2020; 230:104911. [PMID: 32353357 DOI: 10.1016/j.chemphyslip.2020.104911] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 03/04/2020] [Accepted: 03/27/2020] [Indexed: 01/31/2023]
Abstract
Altered lipid metabolism has been linked to cancer development and progression. Several roles have been attributed to the increased saturation and length of lipid acyl tails observed in tumors, but its effect on signaling receptors is still emerging. In this work, we have analyzed the lipid dependence of the ErbB2 growth factor receptor dimerization that plays an important role in the pathogenesis of breast cancer. We have performed coarse-grain ensemble molecular dynamics simulations to comprehensively sample the ErbB2 monomer-dimer association. Our results indicate a dynamic dimer state with a complex conformational landscape that is modulated with increasing lipid tail length. We resolve the native N-terminal "active" and C-terminal "inactive" conformations in all membrane compositions. However, the relative population of the N-terminal and C-terminal conformers is dependent on length of the saturated lipid tails. In short-tail membranes, additional non-specific dimers are observed which are reduced or absent in long-tailed bilayers. Our results indicate that the relative population as well as the structure of the dimer state is modulated by membrane composition. We have correlated these differences to local perturbations of the membrane around the receptor. Our work is an important step in characterizing ErbB dimers in healthy and diseased states and emphasize the importance of sampling lipid dynamics in understanding receptor association.
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Affiliation(s)
- Srinivasa M Gopal
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008, India; Lehrstuhl fur Theoretische Chemie, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Aiswarya B Pawar
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008, India; AcSIR, Mathura Road, New Delhi, 110 025, India
| | - Tsjerk A Wassenaar
- Molecular Dynamics, University of Groningen, Nijenborgh 7, 9747AG Groningen, the Netherlands
| | - Durba Sengupta
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008, India; AcSIR, Mathura Road, New Delhi, 110 025, India.
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36
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Noh SY, Nash A, Notman R. The aggregation of striped nanoparticles in mixed phospholipid bilayers. NANOSCALE 2020; 12:4868-4881. [PMID: 31916561 DOI: 10.1039/c9nr07106g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The unique and adjustable properties of nanoparticles present enormous opportunities for their use as targeted drug delivery vectors. For example, nanoparticles functionalized with key surface ligands have been shown to pass through phospholipid bilayers without causing localised disruption. However, the further effects nanoparticles have on multi-component phospholipid bilayers remain unclear. We use coarse-grained computational models to investigate the structural properties of mixed phospholipid bilayers in the presence of ligand-functionalized nanoparticles. Model bilayers are composed of DPPC, DUPC, DFPC and cholesterol, and the nanoparticles are striped with a hydrophobic-ligand band and charged-ligand spherical caps. Our results show that nanoparticles aggregate near unsaturated phospholipid regions, phospholipid bilayer phase-separation is promoted in the presence of nanoparticles, and the heterogeneous components of a phospholipid bilayer play a significant role in the lateral organization of nanoparticles. This study highlights the need for considering the complexity of realistic phospholipid bilayers when optimising ligand functionalized nanoparticles for efficient drug delivery vectors.
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Affiliation(s)
- Sang Young Noh
- Department of Chemistry, University of Warwick, Coventry, UK.
| | - Anthony Nash
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Rebecca Notman
- Department of Chemistry, University of Warwick, Coventry, UK.
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37
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Loschwitz J, Olubiyi OO, Hub JS, Strodel B, Poojari CS. Computer simulations of protein-membrane systems. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 170:273-403. [PMID: 32145948 PMCID: PMC7109768 DOI: 10.1016/bs.pmbts.2020.01.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The interactions between proteins and membranes play critical roles in signal transduction, cell motility, and transport, and they are involved in many types of diseases. Molecular dynamics (MD) simulations have greatly contributed to our understanding of protein-membrane interactions, promoted by a dramatic development of MD-related software, increasingly accurate force fields, and available computer power. In this chapter, we present available methods for studying protein-membrane systems with MD simulations, including an overview about the various all-atom and coarse-grained force fields for lipids, and useful software for membrane simulation setup and analysis. A large set of case studies is discussed.
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Affiliation(s)
- Jennifer Loschwitz
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
| | - Olujide O Olubiyi
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany; Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Nigeria
| | - Jochen S Hub
- Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken, Germany
| | - Birgit Strodel
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
| | - Chetan S Poojari
- Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken, Germany.
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38
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Jefferies D, Khalid S. Atomistic and coarse-grained simulations of membrane proteins: A practical guide. Methods 2020; 185:15-27. [PMID: 32084518 DOI: 10.1016/j.ymeth.2020.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 02/07/2020] [Accepted: 02/14/2020] [Indexed: 12/12/2022] Open
Abstract
Membrane proteins are amphipathic macromolecules whose exposed hydrophobic surfaces promote interactions with lipid membranes. Membrane proteins are remarkably diverse in terms of chemical composition and correspondingly, their biological functions and general biophysical behavior. Conventional experimental techniques provide an approach to study specific properties of membrane proteins e.g. their surface features, the nature and abundance of stabilizing intramolecular forces, preferred bilayer orientation, and the characteristics of their annular lipid shells. Molecular modeling software-and in particular, the suite of molecular dynamics algorithms-enables a more comprehensive exploration of dynamic membrane protein behavior. Molecular dynamics methods enable users to produce stepwise trajectories of proteins on arbitrary spatiotemporal scales that enable the easy identification of dynamic interactions that are beyond the scope of conventional analytical techniques. This article explains the molecular dynamics theoretical framework and popular step-by-step approaches for simulating membrane proteins in planar, and to a lesser extent, nonplanar lipid geometries. We detail popular procedures and computational tools that produce well-packed configurations of lipids and proteins and additionally, the efficient molecular dynamics simulation algorithms that reproduce their dynamic interactions.
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Affiliation(s)
- Damien Jefferies
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK.
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Fuladi S, Jannat RW, Shen L, Weber CR, Khalili-Araghi F. Computational Modeling of Claudin Structure and Function. Int J Mol Sci 2020; 21:ijms21030742. [PMID: 31979311 PMCID: PMC7037046 DOI: 10.3390/ijms21030742] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 01/16/2020] [Accepted: 01/16/2020] [Indexed: 12/18/2022] Open
Abstract
Tight junctions form a barrier to control passive transport of ions and small molecules across epithelia and endothelia. In addition to forming a barrier, some of claudins control transport properties of tight junctions by forming charge- and size-selective ion channels. It has been suggested claudin monomers can form or incorporate into tight junction strands to form channels. Resolving the crystallographic structure of several claudins in recent years has provided an opportunity to examine structural basis of claudins in tight junctions. Computational and theoretical modeling relying on atomic description of the pore have contributed significantly to our understanding of claudin pores and paracellular transport. In this paper, we review recent computational and mathematical modeling of claudin barrier function. We focus on dynamic modeling of global epithelial barrier function as a function of claudin pores and molecular dynamics studies of claudins leading to a functional model of claudin channels.
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Affiliation(s)
- Shadi Fuladi
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA; (S.F.); (R.-W.J.)
| | - Ridaka-Wal Jannat
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA; (S.F.); (R.-W.J.)
| | - Le Shen
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA;
- Department of Surgery, University of Chicago, Chicago, IL 60637, USA
| | - Christopher R. Weber
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA;
- Correspondence: (C.R.W.); (F.K.-A.)
| | - Fatemeh Khalili-Araghi
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA; (S.F.); (R.-W.J.)
- Correspondence: (C.R.W.); (F.K.-A.)
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40
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Rajagopal N, Irudayanathan FJ, Nangia S. Computational Nanoscopy of Tight Junctions at the Blood-Brain Barrier Interface. Int J Mol Sci 2019; 20:E5583. [PMID: 31717316 PMCID: PMC6888702 DOI: 10.3390/ijms20225583] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 11/05/2019] [Accepted: 11/06/2019] [Indexed: 12/16/2022] Open
Abstract
The selectivity of the blood-brain barrier (BBB) is primarily maintained by tight junctions (TJs), which act as gatekeepers of the paracellular space by blocking blood-borne toxins, drugs, and pathogens from entering the brain. The BBB presents a significant challenge in designing neurotherapeutics, so a comprehensive understanding of the TJ architecture can aid in the design of novel therapeutics. Unraveling the intricacies of TJs with conventional experimental techniques alone is challenging, but recently developed computational tools can provide a valuable molecular-level understanding of TJ architecture. We employed the computational methods toolkit to investigate claudin-5, a highly expressed TJ protein at the BBB interface. Our approach started with the prediction of claudin-5 structure, evaluation of stable dimer conformations and nanoscale assemblies, followed by the impact of lipid environments, and posttranslational modifications on these claudin-5 assemblies. These led to the study of TJ pores and barriers and finally understanding of ion and small molecule transport through the TJs. Some of these in silico, molecular-level findings, will need to be corroborated by future experiments. The resulting understanding can be advantageous towards the eventual goal of drug delivery across the BBB. This review provides key insights gleaned from a series of state-of-the-art nanoscale simulations (or computational nanoscopy studies) performed on the TJ architecture.
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Affiliation(s)
| | | | - Shikha Nangia
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY 13244, USA
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41
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Discovery of Novel Multi-target Inhibitor of angiotensin type 1 receptor and neprilysin inhibitors from Traditional Chinese Medicine. Sci Rep 2019; 9:16205. [PMID: 31700033 PMCID: PMC6838339 DOI: 10.1038/s41598-019-52309-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 10/14/2019] [Indexed: 12/11/2022] Open
Abstract
Angiotensin II type-1 receptor–neprilysin inhibitor (ARNi) is consisted of Angiotensin II type-1 receptor (AT1) antagonist and neprilysin (NEP) inhibitor, which could simultaneously increase the vasodilators of the natriuretic peptides and antagonize vasoconstrictors of Ang II. ARNi has been proved a superior effect and lower risks of death on chronic heart failure (CHF) and hypertension. In this paper, ARNi from Traditional Chinese Medicines (TCM) was discovered based on target combination of AT1 and NEP by virtual screening, biological assay and molecular dynamics (MD) simulations. Two customized strategies of combinatorial virtual screening were implemented to discover AT1 antagonist and NEP inhibitor based on pharmacophore modeling and docking computation respectively. Gyrophoric acid (PubChem CID: 135728) from Parmelia saxatilis was selected as AT1 antagonist and assayed with IC50 of 29.76 μM by calcium influx assay. And 3,5,3′-triiodothyronine (PubChem CID: 861) from Bos taurus domesticus was screened as NEP inhibitor and has a dose dependent inhibitory activity by biochemistry fluorescence assay. Combined with MD simulations, these compounds can generate interaction with the target, key interactive residues of ARG167, TRP84, and VAL108 in AT1, and HIS711 in NEP were also identified respectively. This study designs the combinatorial strategy to discover novel frames of ARNi from TCM, and gyrophoric acid and 3,5,3′-triiodothyronine could provide the clues and revelations of drug design and therapeutic method of CHF and hypertension for TCM clinical applications.
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42
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Augustyn B, Stepien P, Poojari C, Mobarak E, Polit A, Wisniewska-Becker A, Róg T. Cholesteryl Hemisuccinate Is Not a Good Replacement for Cholesterol in Lipid Nanodiscs. J Phys Chem B 2019; 123:9839-9845. [DOI: 10.1021/acs.jpcb.9b07853] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
| | - Piotr Stepien
- Bionanoscience and Biochemistry Laboratory, Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7A, 30-387 Krakow, Poland
| | - Chetan Poojari
- Department of Physics, Faculty of Science, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Theoretical Physics and Center for Biophysics, Saarland University, 66123 Saarbrücken, Germany
| | - Edouard Mobarak
- Department of Physics, Faculty of Science, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | | | | | - Tomasz Róg
- Department of Physics, Faculty of Science, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
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43
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Nangia S, Boyd KJ, May ER. Molecular dynamics study of membrane permeabilization by wild-type and mutant lytic peptides from the non-enveloped Flock House virus. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183102. [PMID: 31678020 DOI: 10.1016/j.bbamem.2019.183102] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 09/16/2019] [Accepted: 10/14/2019] [Indexed: 12/19/2022]
Abstract
Flock House virus (FHV) serves as a model system for understanding infection mechanisms utilized by non-enveloped viruses to transport across cellular membranes. During the infection cycle of FHV, a fundamental stage involves disruption of the endosomal membrane by membrane active peptides, following externalization of the peptides from the capsid interior. The FHV lytic agents are the 44 C-terminal amino acids residues of the capsid protein, which are auto-catalytically cleaved during the capsid maturation process. The cleaved peptides are termed γ peptides. In this study, we perform multi-scale molecular dynamics simulations including 40 μs all-atom molecular dynamics simulations to study the behavior of pre-inserted transmembrane lytic peptides at a high concentration in a neutral membrane. We study the dynamical organization among peptides to form oligomeric bundles in four systems including the wild-type γ peptide and three mutant forms; namely, a truncation mutant in which the 23 C-terminal residues are deleted (γ1), a construct where the 8 C-terminal residues of γ are fused to γ1 (Δ385-399 γ) and a single-point mutant (F402A γ), all of which have been experimentally shown to drastically affect infectivity and lytic activity compared to the wild-type γ. Our results shed light on the actions of varied forms of the FHV lytic peptide including membrane insertion, trans-membrane stability, peptide oligomerization, water permeation activity and dynamic pore formation. Findings from this study provide detailed structural information and rationale for the differences in lytic activity among variants of FHV γ.
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Affiliation(s)
- Shivangi Nangia
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, United States of America
| | - Kevin J Boyd
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, United States of America
| | - Eric R May
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, United States of America.
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44
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Bhatia H, Ingólfsson HI, Carpenter TS, Lightstone FC, Bremer PT. MemSurfer: A Tool for Robust Computation and Characterization of Curved Membranes. J Chem Theory Comput 2019; 15:6411-6421. [DOI: 10.1021/acs.jctc.9b00453] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Harsh Bhatia
- Center for Applied Scientific Computing, Computation Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Helgi I. Ingólfsson
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Timothy S. Carpenter
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Felice C. Lightstone
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Peer-Timo Bremer
- Center for Applied Scientific Computing, Computation Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
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45
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Mesa-Galloso H, Valiente PA, Valdés-Tresanco ME, Epand RF, Lanio ME, Epand RM, Alvarez C, Tieleman DP, Ros U. Membrane Remodeling by the Lytic Fragment of SticholysinII: Implications for the Toroidal Pore Model. Biophys J 2019; 117:1563-1576. [PMID: 31587828 DOI: 10.1016/j.bpj.2019.09.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 09/07/2019] [Accepted: 09/09/2019] [Indexed: 01/15/2023] Open
Abstract
Sticholysins are pore-forming toxins of biomedical interest and represent a prototype of proteins acting through the formation of protein-lipid or toroidal pores. Peptides spanning the N-terminus of sticholysins can mimic their permeabilizing activity and, together with the full-length toxins, have been used as a tool to understand the mechanism of pore formation in membranes. However, the lytic mechanism of these peptides and the lipid shape modulating their activity are not completely clear. In this article, we combine molecular dynamics simulations and experimental biophysical tools to dissect different aspects of the pore-forming mechanism of StII1-30, a peptide derived from the N-terminus of sticholysin II (StII). With this combined approach, membrane curvature induction and flip-flop movement of the lipids were identified as two important membrane remodeling steps mediated by StII1-30. Pore formation by this peptide was enhanced by the presence of the negatively curved lipid phosphatidylethanolamine in membranes. This lipid emerged not only as a facilitator of membrane interactions but also as a structural element of the StII1-30 pore that is recruited to the ring upon its assembly. Collectively, these, to our knowledge, new findings support a toroidal model for the architecture of the pore formed by StII1-30 and provide new molecular insight into the role of phosphatidylethanolamine as a membrane component that can easily integrate into the ring of toroidal pores, thus probably aiding in their stabilization. This study contributes to a better understanding of the molecular mechanism underlying the permeabilizing activity of StII1-30 and peptides or proteins acting via a toroidal pore mechanism and offers an informative framework for the optimization of the biomedical application of this and similar molecules.
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Affiliation(s)
- Haydee Mesa-Galloso
- Department of Biological Sciences and Centre for Molecular Simulation, University of Calgary, Calgary, Alberta, Canada; Center for Protein Studies, Faculty of Biology, University of Havana, Havana, Cuba
| | - Pedro A Valiente
- Center for Protein Studies, Faculty of Biology, University of Havana, Havana, Cuba
| | - Mario E Valdés-Tresanco
- Department of Biological Sciences and Centre for Molecular Simulation, University of Calgary, Calgary, Alberta, Canada; Center for Protein Studies, Faculty of Biology, University of Havana, Havana, Cuba
| | - Raquel F Epand
- Department of Biochemistry and Biomedical Sciences, Health Science Center, McMaster University, Hamilton, Ontario, Canada
| | - Maria E Lanio
- Center for Protein Studies, Faculty of Biology, University of Havana, Havana, Cuba
| | - Richard M Epand
- Department of Biochemistry and Biomedical Sciences, Health Science Center, McMaster University, Hamilton, Ontario, Canada
| | - Carlos Alvarez
- Center for Protein Studies, Faculty of Biology, University of Havana, Havana, Cuba
| | - D Peter Tieleman
- Department of Biological Sciences and Centre for Molecular Simulation, University of Calgary, Calgary, Alberta, Canada.
| | - Uris Ros
- Center for Protein Studies, Faculty of Biology, University of Havana, Havana, Cuba; Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany.
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46
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Nikte S, Gahankari A, Mulla J, Sengupta D, Joshi M, Tamhane V. In vitro and in silico studies on membrane interactions of diverseCapsicum annuumflower γ‐thionin peptides. Proteins 2019; 88:227-236. [DOI: 10.1002/prot.25791] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 07/15/2019] [Accepted: 07/27/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Siddhanta Nikte
- Bioinformatics CentreSavitribai Phule Pune University Pune Maharashtra India
- Physical Chemistry DivisionNational Chemical Laboratory Pune Maharashtra India
| | - Apurva Gahankari
- Institute of Bioinformatics and BiotechnologySavitribai Phule Pune University Pune Maharashtra India
| | - Javed Mulla
- Institute of Bioinformatics and BiotechnologySavitribai Phule Pune University Pune Maharashtra India
| | - Durba Sengupta
- Physical Chemistry DivisionNational Chemical Laboratory Pune Maharashtra India
| | - Manali Joshi
- Bioinformatics CentreSavitribai Phule Pune University Pune Maharashtra India
| | - Vaijayanti Tamhane
- Institute of Bioinformatics and BiotechnologySavitribai Phule Pune University Pune Maharashtra India
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47
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Kumar S, Thakur J, Yadav K, Mitra M, Pal S, Ray A, Gupta S, Medatwal N, Gupta R, Mishra D, Rani P, Padhi S, Sharma P, Kapil A, Srivastava A, Priyakumar UD, Dasgupta U, Thukral L, Bajaj A. Cholic Acid-Derived Amphiphile which Combats Gram-Positive Bacteria-Mediated Infections via Disintegration of Lipid Clusters. ACS Biomater Sci Eng 2019; 5:4764-4775. [PMID: 33448819 DOI: 10.1021/acsbiomaterials.9b00706] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Inappropriate and uncontrolled use of antibiotics results in the emergence of antibiotic resistance, thereby threatening the present clinical regimens to treat infectious diseases. Therefore, new antimicrobial agents that can prevent bacteria from developing drug resistance are urgently needed. Selective disruption of bacterial membranes is the most effective strategy for combating microbial infections as accumulation of genetic mutations will not allow for the emergence of drug resistance against these antimicrobials. In this work, we tested cholic acid (CA) derived amphiphiles tethered with different alkyl chains for their ability to combat Gram-positive bacterial infections. In-depth biophysical and biomolecular simulation studies suggested that the amphiphile with a hexyl chain (6) executes more effective interactions with Gram-positive bacterial membranes as compared to other hydrophobic counterparts. Amphiphile 6 is effective against multidrug resistant Gram-positive bacterial strains as well and does not allow the adherence of S. aureus on amphiphile 6 coated catheters implanted in mice. Further, treatment of wound infections with amphiphile 6 clears the bacterial infections. Therefore, the current study presents strategic guidelines in design and development of CA-derived membrane-targeting antimicrobials for Gram-positive bacterial infections.
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Affiliation(s)
- Sandeep Kumar
- Laboratory of Nanotechnology and Chemical Biology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad-121001, Haryana, India.,Manipal Academy of Higher Education, Tiger Circle Road, Madhav Nagar, Manipal-576104, Karnataka, India
| | - Jyoti Thakur
- Department of Chemistry, Indian Institute of Science Education and Research, Bhopal Bypass Road, Bhauri, Bhopal-462066, Madhya Pradesh, India
| | - Kavita Yadav
- Laboratory of Nanotechnology and Chemical Biology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad-121001, Haryana, India.,Manipal Academy of Higher Education, Tiger Circle Road, Madhav Nagar, Manipal-576104, Karnataka, India
| | - Madhurima Mitra
- Laboratory of Nanotechnology and Chemical Biology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad-121001, Haryana, India
| | - Sanjay Pal
- Laboratory of Nanotechnology and Chemical Biology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad-121001, Haryana, India.,Kalinga Institute of Industrial Technology, KIIT Road, Patia, Bhubaneswar-751024, Odisha, India
| | - Arjun Ray
- CSIR-Institute of Genomics and Integrative Biology, South Campus, Mathura Road, Opp: Sukhdev Vihar Bus Depot, New Delhi-110025, India
| | - Siddhi Gupta
- Laboratory of Nanotechnology and Chemical Biology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad-121001, Haryana, India
| | - Nihal Medatwal
- Laboratory of Nanotechnology and Chemical Biology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad-121001, Haryana, India
| | - Ragini Gupta
- Laboratory of Nanotechnology and Chemical Biology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad-121001, Haryana, India
| | - Deepakkumar Mishra
- Laboratory of Nanotechnology and Chemical Biology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad-121001, Haryana, India
| | - Parul Rani
- Laboratory of Nanotechnology and Chemical Biology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad-121001, Haryana, India
| | - Siladitya Padhi
- Centre for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology, Professor CR Rao Road, Gachibowli, Hyderabad-500032, India
| | - Priyanka Sharma
- Department of Microbiology, All India Institute of Medical Sciences, Sri Aurobindo Marg, Ansari Nagar, New Delhi-110029, India
| | - Arti Kapil
- Department of Microbiology, All India Institute of Medical Sciences, Sri Aurobindo Marg, Ansari Nagar, New Delhi-110029, India
| | - Aasheesh Srivastava
- Department of Chemistry, Indian Institute of Science Education and Research, Bhopal Bypass Road, Bhauri, Bhopal-462066, Madhya Pradesh, India
| | - U Deva Priyakumar
- Centre for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology, Professor CR Rao Road, Gachibowli, Hyderabad-500032, India
| | - Ujjaini Dasgupta
- Amity Institute of Integrative Sciences and Health, Amity University, Amity Education Valley Gurugram, Panchgaon, Manesar, Gurugram-122413, Haryana, India
| | - Lipi Thukral
- CSIR-Institute of Genomics and Integrative Biology, South Campus, Mathura Road, Opp: Sukhdev Vihar Bus Depot, New Delhi-110025, India
| | - Avinash Bajaj
- Laboratory of Nanotechnology and Chemical Biology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad-121001, Haryana, India
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48
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Marrink SJ, Corradi V, Souza PC, Ingólfsson HI, Tieleman DP, Sansom MS. Computational Modeling of Realistic Cell Membranes. Chem Rev 2019; 119:6184-6226. [PMID: 30623647 PMCID: PMC6509646 DOI: 10.1021/acs.chemrev.8b00460] [Citation(s) in RCA: 435] [Impact Index Per Article: 87.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 12/15/2022]
Abstract
Cell membranes contain a large variety of lipid types and are crowded with proteins, endowing them with the plasticity needed to fulfill their key roles in cell functioning. The compositional complexity of cellular membranes gives rise to a heterogeneous lateral organization, which is still poorly understood. Computational models, in particular molecular dynamics simulations and related techniques, have provided important insight into the organizational principles of cell membranes over the past decades. Now, we are witnessing a transition from simulations of simpler membrane models to multicomponent systems, culminating in realistic models of an increasing variety of cell types and organelles. Here, we review the state of the art in the field of realistic membrane simulations and discuss the current limitations and challenges ahead.
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Affiliation(s)
- Siewert J. Marrink
- Groningen
Biomolecular Sciences and Biotechnology Institute & Zernike Institute
for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Valentina Corradi
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Paulo C.T. Souza
- Groningen
Biomolecular Sciences and Biotechnology Institute & Zernike Institute
for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Helgi I. Ingólfsson
- Biosciences
and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - D. Peter Tieleman
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Mark S.P. Sansom
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
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49
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Shearer J, Jefferies D, Khalid S. Outer Membrane Proteins OmpA, FhuA, OmpF, EstA, BtuB, and OmpX Have Unique Lipopolysaccharide Fingerprints. J Chem Theory Comput 2019; 15:2608-2619. [PMID: 30848905 DOI: 10.1021/acs.jctc.8b01059] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The outer membrane of Gram-negative bacteria has a highly complex asymmetrical architecture, containing a mixture of phospholipids in the inner leaflet and almost exclusively lipopolysaccharide (LPS) molecules in the outer leaflet. In E. coli, the outer membrane contains a wide range of proteins with a β barrel architecture, that vary in size from the smallest having eight strands to larger barrels composed of 22 strands. Here we report coarse-grained molecular dynamics simulations of six proteins from the E. coli outer membrane OmpA, OmpX, BtuB, FhuA, OmpF, and EstA in a range of membrane environments, which are representative of the in vivo conditions for different strains of E. coli. We show that each protein has a unique pattern of interaction with the surrounding membrane, which is influenced by the composition of the protein, the level of LPS in the outer leaflet, and the differing mobilities of the lipids in the two leaflets of the membrane. Overall we present analyses from over 200 μs of simulation for each protein.
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Affiliation(s)
- Jonathan Shearer
- School of Chemistry , University of Southampton, Highfield , Southampton , SO17 1BJ United Kingdom
| | - Damien Jefferies
- School of Chemistry , University of Southampton, Highfield , Southampton , SO17 1BJ United Kingdom
| | - Syma Khalid
- School of Chemistry , University of Southampton, Highfield , Southampton , SO17 1BJ United Kingdom
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50
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Gupta A, Marzinek JK, Jefferies D, Bond PJ, Harryson P, Wohland T. The disordered plant dehydrin Lti30 protects the membrane during water-related stress by cross-linking lipids. J Biol Chem 2019; 294:6468-6482. [PMID: 30819802 DOI: 10.1074/jbc.ra118.007163] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 02/14/2019] [Indexed: 12/13/2022] Open
Abstract
Dehydrins are intrinsically disordered proteins, generally expressed in plants as a response to embryogenesis and water-related stress. Their suggested functions are in membrane stabilization and cell protection. All dehydrins contain at least one copy of the highly conserved K-segment, proposed to be a membrane-binding motif. The dehydrin Lti30 (Arabidopsis thaliana) is up-regulated during cold and drought stress conditions and comprises six K-segments, each with two adjacent histidines. Lti30 interacts with the membrane electrostatically via pH-dependent protonation of the histidines. In this work, we seek a molecular understanding of the membrane interaction mechanism of Lti30 by determining the diffusion and molecular organization of Lti30 on model membrane systems by imaging total internal reflection- fluorescence correlation spectroscopy (ITIR-FCS) and molecular dynamics (MD) simulations. The dependence of the diffusion coefficient explored by ITIR-FCS together with MD simulations yields insights into Lti30 binding, domain partitioning, and aggregation. The effect of Lti30 on membrane lipid diffusion was studied on fluorescently labeled supported lipid bilayers of different lipid compositions at mechanistically important pH conditions. In parallel, we compared the mode of diffusion for short individual K-segment peptides. The results indicate that Lti30 binds the lipid bilayer via electrostatics, which restricts the mobility of lipids and bound protein molecules. At low pH, Lti30 binding induced lipid microdomain formation as well as protein aggregation, which could be correlated with one another. Moreover, at physiological pH, Lti30 forms nanoscale aggregates when proximal to the membrane suggesting that Lti30 may protect the cell by "cross-linking" the membrane lipids.
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Affiliation(s)
- Anjali Gupta
- From the Center for BioImaging Sciences and.,the Department of Biological Sciences, National University of Singapore, 14 Science Dr. 4, Singapore 117543, Singapore
| | - Jan K Marzinek
- the Bioinformatics Institute (A*STAR), 30 Biopolis St., 07-01 Matrix, Singapore 138671, Singapore
| | - Damien Jefferies
- the Bioinformatics Institute (A*STAR), 30 Biopolis St., 07-01 Matrix, Singapore 138671, Singapore.,the School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - Peter J Bond
- the Department of Biological Sciences, National University of Singapore, 14 Science Dr. 4, Singapore 117543, Singapore.,the Bioinformatics Institute (A*STAR), 30 Biopolis St., 07-01 Matrix, Singapore 138671, Singapore
| | - Pia Harryson
- the Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden, and
| | - Thorsten Wohland
- From the Center for BioImaging Sciences and .,the Department of Biological Sciences, National University of Singapore, 14 Science Dr. 4, Singapore 117543, Singapore.,Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
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