1
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Jaufer AM, Bouhadana A, Kharrazizadeh A, Zhou M, Colina CM, Fanucci GE. Designing surface exposed sites on Bacillus subtilis lipase A for spin-labeling and hydration studies. Biophys Chem 2024; 308:107203. [PMID: 38382282 DOI: 10.1016/j.bpc.2024.107203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 02/09/2024] [Accepted: 02/15/2024] [Indexed: 02/23/2024]
Abstract
Spin-labeling with electron paramagnetic resonance spectroscopy (EPR) is a facile method for interrogating macromolecular flexibility, conformational changes, accessibility, and hydration. Within we present a computationally based approach for the rational selection of reporter sites in Bacillus subtilis lipase A (BSLA) for substitution to cysteine residues with subsequent modification with a spin-label that are expected to not significantly perturb the wild-type structure, dynamics, or enzymatic function. Experimental circular dichroism spectroscopy, Michaelis-Menten kinetic parameters and EPR spectroscopy data validate the success of this approach to computationally select reporter sites for future magnetic resonance investigations of hydration and hydration changes induced by polymer conjugation, tethering, immobilization, or amino acid substitution in BSLA. Analysis of molecular dynamic simulations of the impact of substitutions on the secondary structure agree well with experimental findings. We propose that this computationally guided approach for choosing spin-labeled EPR reporter sites, which evaluates relative surface accessibility coupled with hydrogen bonding occupancy of amino acids to the catalytic pocket via atomistic simulations, should be readily transferable to other macromolecular systems of interest including selecting sites for paramagnetic relaxation enhancement NMR studies, other spin-labeling EPR studies or any method requiring a tagging method where it is desirable to not alter enzyme stability or activity.
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Affiliation(s)
- Afnan M Jaufer
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611, USA; George and Josephine Butler Polymer Research Laboratory, University of Florida, Gainesville, FL 32611, USA.
| | - Adam Bouhadana
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611, USA.
| | - Amir Kharrazizadeh
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611, USA.
| | - Mingwei Zhou
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611, USA.
| | - Coray M Colina
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611, USA; George and Josephine Butler Polymer Research Laboratory, University of Florida, Gainesville, FL 32611, USA; Department of Materials Science and Engineering, University of Florida, PO BOX 117200, Gainesville, FL 32611, USA.
| | - Gail E Fanucci
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611, USA.
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2
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Awad SI, Smadi OA, Tomeh MF, Alzghoul SM. A guideline for the distance measurement plans of site-directed spin labels for structural prediction of nucleic acids. J Mol Model 2023; 30:16. [PMID: 38157075 DOI: 10.1007/s00894-023-05808-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 12/11/2023] [Indexed: 01/03/2024]
Abstract
CONTEXT AND RESULTS Site-directed spin labeling (SDSL) combined with electron paramagnetic resonance spectroscopy methods has been successfully used to predict the structures of nucleic acids. These methods measure the distances between spin labels yielding distance equations that are solved using numerical algorithms to provide one or several structural predictions. In this work, the minimum number of SDSL distance measurements and distance measurement types required to predict a unique nucleic acid structure were investigated. Our results indicate that at least six distance measurements should be obtained given that the distance measurements do not connect one SDSL on one arm with more than three SDSLs on the other arm. Moreover, there may be a preference for 1-to-1 SLs distance measurements rather than 1-to-many SLs as the latter was linked to undefined structures discussed in this study. METHODS Pairs of double-helical arms of nucleic acid were simulated using the finite element software Pro/ENGINEER (PTC Inc., Boston, MA). In each simulation, a specific SDSL distance measurement plan was adopted and the resulting structure was tested for movability. Immovable structures indicate that this plan will potentially result in a unique structural prediction of the nucleic acid. All the possible plans for SDSL distance measurements were investigated either by direct measurement or by extrapolation.
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Affiliation(s)
- Samer I Awad
- Department of Biomedical Engineering, Faculty of Engineering, The Hashemite University, P.O. Box 330127, Zarqa, 13133, Jordan.
| | - Othman A Smadi
- Department of Biomedical Engineering, Faculty of Engineering, The Hashemite University, P.O. Box 330127, Zarqa, 13133, Jordan
| | - Mohammed F Tomeh
- Department of Industrial Engineering, Faculty of Engineering, The Hashemite University, P.O. Box 330127, Zarqa, 13133, Jordan
| | - Salah M Alzghoul
- Department of Biomedical Engineering, Faculty of Engineering, The Hashemite University, P.O. Box 330127, Zarqa, 13133, Jordan
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3
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Dunleavy KM, Li T, Milshteyn E, Jaufer AM, Walker SA, Fanucci GE. Charge Distribution Patterns of IA 3 Impact Conformational Expansion and Hydration Diffusivity of the Disordered Ensemble. J Phys Chem B 2023; 127:9734-9746. [PMID: 37936402 DOI: 10.1021/acs.jpcb.3c06170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
IA3 is a 68 amino acid natural peptide/protein inhibitor of yeast aspartic proteinase A (YPRA) that is intrinsically disordered in solution with induced N-terminal helicity when in the protein complex with YPRA. Based on the intrinsically disordered protein (IDP) parameters of fractional net charge (FNC), net charge density per residue (NCPR), and charge patterning (κ), the two domains of IA3 are defined to occupy different domains within conformationally based subclasses of IDPs, thus making IA3 a bimodal domain IDP. Site-directed spin labeling (SDSL) electron paramagnetic resonance (EPR) spectroscopy and low-field Overhauser dynamic nuclear polarization (ODNP) spectroscopy results show that these two domains possess different degrees of compaction and hydration diffusivity behavior. This work suggests that SDSL EPR line shapes, analyzed in terms of their local tumbling volume (VL), provide insights into the compaction of the unstructured IDP ensemble in solution and that protein sequence and net charge distribution patterns within a conformational subclass can impact bound water hydration dynamics, thus possibly offering an alternative thermodynamic property that can encode conformational binding and behavior of IDPs and liquid-liquid phase separations.
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Affiliation(s)
- Katie M Dunleavy
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Tianyan Li
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Eugene Milshteyn
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Afnan M Jaufer
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Shamon A Walker
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States
| | - Gail E Fanucci
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
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4
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Khan RH, Rotich NC, Morris A, Ahammad T, Baral B, Sahu ID, Lorigan GA. Probing the Structural Topology and Dynamic Properties of gp28 Using Continuous Wave Electron Paramagnetic Resonance Spectroscopy. J Phys Chem B 2023; 127:9236-9247. [PMID: 37856870 DOI: 10.1021/acs.jpcb.3c03679] [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: 10/21/2023]
Abstract
Lysis of Gram-negative bacteria by dsDNA phages is accomplished through either the canonical holin-endolysin pathway or the pinholin-SAR endolysin pathway. During lysis, the outer membrane (OM) is disrupted, typically by two-component spanins or unimolecular spanins. However, in the absence of spanins, phages use alternative proteins called Disruptin to disrupt the OM. The Disruptin family includes the cationic antimicrobial peptide gp28, which is found in the virulent podophage φKT. In this study, EPR spectroscopy was used to analyze the dynamics and topology of gp28 incorporated into a lipid bilayer, revealing differences in mobility, depth parameter, and membrane interaction among different segments and residues of the protein. Our results indicate that multiple points of helix 2 and helix 3 interact with the phospholipid membrane, while others are solvent-exposed, suggesting that gp28 is a surface-bound peptide. The CW-EPR power saturation data and helical wheel analysis confirmed the amphipathic-helical structure of gp28. Additionally, course-grain molecular dynamics simulations were further used to develop the structural model of the gp28 peptide associated with the lipid bilayers. Based on the data obtained in this study, we propose a structural topology model for gp28 with respect to the membrane. This work provides important insights into the structural and dynamic properties of gp28 incorporated into a lipid bilayer environment.
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Affiliation(s)
- Rasal H Khan
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Nancy C Rotich
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Andrew Morris
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Tanbir Ahammad
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Binaya Baral
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Indra D Sahu
- Natural Science Division, Campbellsville University, Campbellsville, Kentucky 42718, United States
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
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5
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Kumashiro M, Matsuo K. Characterization of membrane-interaction mechanisms of proteins using vacuum-ultraviolet circular dichroism spectroscopy. Chirality 2023; 35:826-837. [PMID: 37418251 DOI: 10.1002/chir.23607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/30/2023] [Accepted: 06/21/2023] [Indexed: 07/08/2023]
Abstract
Protein-membrane interactions play an important role in various biological phenomena, such as material transport, demyelinating diseases, and antimicrobial activity. We combined vacuum-ultraviolet circular dichroism (VUVCD) spectroscopy with theoretical (e.g., molecular dynamics and neural networks) and polarization experimental (e.g., linear dichroism and fluorescence anisotropy) methods to characterize the membrane interaction mechanisms of three soluble proteins (or peptides). α1 -Acid glycoprotein has the drug-binding ability, but the combination of VUVCD and neural-network method revealed that the membrane interaction causes the extension of helix in the N-terminal region, which reduces the binding ability. Myelin basic protein (MBP) is an essential component of the myelin sheath with a multi-layered structure. Molecular dynamics simulations using a VUVCD-guided system showed that MBP forms two amphiphilic and three non-amphiphilic helices as membrane interaction sites. These multivalent interactions may allow MBP to interact with two opposing membrane leaflets, contributing to the formation of a multi-layered myelin structure. The antimicrobial peptide magainin 2 interacts with the bacterial membrane, causing damage to its structure. VUVCD analysis revealed that the M2 peptides assemble in the membrane and turn into oligomers with a β-strand structure. Linear dichroism and fluorescence anisotropy suggested that the oligomers are inserted into the hydrophobic core of the membrane, disrupting the bacterial membrane. Overall, our findings demonstrate that VUVCD and its combination with theoretical and polarization experimental methods pave the way for unraveling the molecular mechanisms of biological phenomena related to protein-membrane interactions.
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Affiliation(s)
- Munehiro Kumashiro
- Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
| | - Koichi Matsuo
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
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6
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Scheyer MW, Campbell C, William PL, Hussain M, Begum A, Fonseca SE, Asare IK, Dabney P, Dabney-Smith C, Lorigan GA, Sahu ID. Electron paramagnetic resonance spectroscopic characterization of the human KCNE3 protein in lipodisq nanoparticles for structural dynamics of membrane proteins. Biophys Chem 2023; 301:107080. [PMID: 37531799 DOI: 10.1016/j.bpc.2023.107080] [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: 05/25/2023] [Revised: 07/07/2023] [Accepted: 07/24/2023] [Indexed: 08/04/2023]
Abstract
One of the major challenges in solubilization of membrane proteins is to find the optimal physiological environment for their biophysical studies. EPR spectroscopy is a powerful biophysical technique for studying the structural and dynamic properties of macromolecules. However, the challenges in the membrane protein sample preparation and flexible motion of the spin label limit the utilization of EPR spectroscopy to a majority of membrane protein systems in a physiological membrane-bound state. Recently, lipodisq nanoparticles or styrene-maleic acid copolymer-lipid nanoparticles (SMALPs) have emerged as a membrane mimetic system for investigating the structural studies of membrane proteins. However, its detail characterization for membrane protein studies is still poorly understood. Recently, we characterized the potassium channel membrane protein KCNQ1 voltage sensing domain (KCNQ1-VSD) and KCNE1 reconstituted into lipodisq nanoparticles using EPR spectroscopy. In this study, the potassium channel accessory protein KCNE3 containing flexible N- and C-termini was encapsulated into proteoliposomes and lipodisq nanoparticles and characterized for studying its structural and dynamic properties using nitroxide based site-directed spin labeling EPR spectroscopy. CW-EPR lineshape analysis data indicated an increase in spectral line broadenings with the addition of the styrene-maleic acid (SMA) polymer which approaches close to the rigid limit providing a homogeneous stabilization of the protein-lipid complex. Similarly, EPR DEER measurements indicated an enhanced quality of distance measurements with an increase in the phase memory time (Tm) values upon incorporation of the sample into lipodisq nanoparticles, when compared to proteoliposomes. These results agree with the solution NMR structural structure of the KCNE3 and EPR studies of other membrane proteins in lipodisq nanoparticles. This study along with our earlier studies will provide the reference characterization data that will provide benefit to the membrane protein researchers for studying structural dynamics of challenging membrane proteins.
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Affiliation(s)
- Matthew W Scheyer
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Conner Campbell
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Patrick L William
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Mustakim Hussain
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Afsana Begum
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | | | - Isaac K Asare
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Peyton Dabney
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Carole Dabney-Smith
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Indra D Sahu
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA; Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA.
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7
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Khoroshunova YV, Morozov DA, Kuznetsov DA, Rybalova TV, Glazachev YI, Bagryanskaya EG, Kirilyuk IA. Synthesis and Properties of (1 R( S),5 R( S),7 R( S),8 R( S))-1,8-Bis(hydroxymethyl)-6-azadispiro[4.1.4.2]tridecane-6-oxyl: Reduction-Resistant Spin Labels with High Spin Relaxation Times. Int J Mol Sci 2023; 24:11498. [PMID: 37511257 PMCID: PMC10380268 DOI: 10.3390/ijms241411498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 07/12/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023] Open
Abstract
Site-directed spin labeling followed by investigation using Electron Paramagnetic Resonance spectroscopy is a rapidly expanding powerful biophysical technique to study structure, local dynamics and functions of biomolecules using pulsed EPR techniques and nitroxides are the most widely used spin labels. Modern trends of this method include measurements directly inside a living cell, as well as measurements without deep freezing (below 70 K), which provide information that is more consistent with the behavior of the molecules under study in natural conditions. Such studies require nitroxides, which are resistant to the action of biogenic reductants and have high spin relaxation (dephasing) times, Tm. (1R(S),5R(S),7R(S),8R(S))-1,8-bis(hydroxymethyl)-6-azadispiro[4.1.4.2]tridecane-6-oxyl is a unique nitroxide that combines these features. We have developed a convenient method for the synthesis of this radical and studied the ways of its functionalization. Promising spin labels have been obtained, the parameters of their spin relaxation T1 and Tm have been measured, and the kinetics of reduction with ascorbate have been studied.
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Affiliation(s)
- Yulia V Khoroshunova
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, Academician Lavrentiev Ave. 9, 630090 Novosibirsk, Russia
- Department of Physics, Novosibirsk State University, Pirogova Str. 1, 630090 Novosibirsk, Russia
| | - Denis A Morozov
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, Academician Lavrentiev Ave. 9, 630090 Novosibirsk, Russia
| | - Danil A Kuznetsov
- Department of Physics, Novosibirsk State University, Pirogova Str. 1, 630090 Novosibirsk, Russia
| | - Tatyana V Rybalova
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, Academician Lavrentiev Ave. 9, 630090 Novosibirsk, Russia
| | - Yurii I Glazachev
- Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, Institutskaya 3, 630090 Novosibirsk, Russia
| | - Elena G Bagryanskaya
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, Academician Lavrentiev Ave. 9, 630090 Novosibirsk, Russia
| | - Igor A Kirilyuk
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, Academician Lavrentiev Ave. 9, 630090 Novosibirsk, Russia
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8
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Jaiswal M, Tran TT, Guo J, Zhou M, Kunda S, Guo Z, Fanucci G. Spin-labeling Insights into How Chemical Fixation Impacts Glycan Organization on Cells. RESEARCH SQUARE 2023:rs.3.rs-3039983. [PMID: 37398188 PMCID: PMC10312935 DOI: 10.21203/rs.3.rs-3039983/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
As new methods to interrogate glycan organization on cells develop, it is important to have a molecular level understanding of how chemical fixation can impact results and interpretations. Site-directed spin labeling technologies are well suited to study how the spin label mobility is impacted by local environmental conditions, such as those imposed by cross-linking effects of paraformaldehyde cell fixation methods. Here, we utilize three different azide-containing sugars for metabolic glycan engineering with HeLa cells to incorporate azido glycans that are modified with a DBCO-based nitroxide moiety via click reaction. Continuous wave X-band electron paramagnetic resonance spectroscopy is employed to characterize how the chronological sequence of chemical fixation and spin labeling impacts the local mobility and accessibility of the nitroxide-labeled glycans in the glycocalyx of HeLa cells. Results demonstrate that chemical fixation with paraformaldehyde can alter local glycan mobility and care should be taken in the analysis of data in any study where chemical fixation and cellular labeling occur.
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9
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Morris AK, Perera RS, Sahu ID, Lorigan GA. Topological examination of the bacteriophage lambda S holin by EPR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184083. [PMID: 36370910 PMCID: PMC9771973 DOI: 10.1016/j.bbamem.2022.184083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 10/26/2022] [Accepted: 10/31/2022] [Indexed: 11/11/2022]
Abstract
The S protein from bacteriophage lambda is a three-helix transmembrane protein produced by the prophage which accumulates in the host membrane during late gene expression. It is responsible for the first step in lysing the host cell at the end of the viral life cycle by multimerizing together to form large pores which permeabilize the host membrane to allow the escape of virions. Several previous studies have established a model for the assembly of holin into functional holes and the manner in which they pack together, but it is still not fully understood how the very rapid transition from monomer or dimer to multimeric pore occurs with such precise timing once the requisite threshold is reached. Here, site-directed spin labeling with a nitroxide label at introduced cysteine residues is used to corroborate existing topological data from a crosslinking study of the multimerized holin by EPR spectroscopy. CW-EPR spectral lineshape analysis and power saturation data are consistent with a three-helix topology with an unstructured C-terminal domain, as well as at least one interface on transmembrane domain 1 which is exposed to the lumen of the hole, and a highly constrained steric environment suggestive of a tight helical packing interface at transmembrane domain 2.
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Affiliation(s)
- Andrew K Morris
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA.
| | - Rehani S Perera
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA.
| | - Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA; Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA.
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA.
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10
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Brahma R, Raghuraman H. Measuring Membrane Penetration Depths and Conformational Changes in Membrane Peptides and Proteins. J Membr Biol 2022; 255:469-483. [PMID: 35274157 DOI: 10.1007/s00232-022-00224-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 02/23/2022] [Indexed: 10/18/2022]
Abstract
The structural organization and dynamic nature of the biomembrane components are important determinants for numerous cellular functions. Particularly, membrane proteins are critically important for various physiological functions and are important drug targets. The mechanistic insights on the complex functionality of membrane lipids and proteins can be elucidated by understanding the interplay between structure and dynamics. In this regard, membrane penetration depth represents an important parameter to obtain the precise depth of membrane-embedded molecules that often define the conformation and topology of membrane probes and proteins. In this review, we discuss about the widely used fluorescence quenching-based methods (parallax method, distribution analysis, and dual-quencher analysis) to accurately determine the membrane penetration depths of fluorescent probes that are either membrane-embedded or attached to lipids and proteins. Further, we also discuss a relatively novel fluorescence quenching method that utilizes tryptophan residue as the quencher, namely the tryptophan-induced quenching, which is sensitive to monitor small-scale conformational changes (short distances of < 15 Å) and useful in mapping distances in proteins. We have provided numerous examples for the benefit of readers to appreciate the importance and applicability of these simple yet powerful methods to study membrane proteins.
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Affiliation(s)
- Rupasree Brahma
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, 1/AF, Bidhannagar, Kolkata, 700 064, India
| | - H Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, 1/AF, Bidhannagar, Kolkata, 700 064, India.
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11
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Puthenveetil R, Christenson ET, Vinogradova O. New Horizons in Structural Biology of Membrane Proteins: Experimental Evaluation of the Role of Conformational Dynamics and Intrinsic Flexibility. MEMBRANES 2022; 12:227. [PMID: 35207148 PMCID: PMC8877495 DOI: 10.3390/membranes12020227] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 02/13/2022] [Accepted: 02/14/2022] [Indexed: 02/08/2023]
Abstract
A plethora of membrane proteins are found along the cell surface and on the convoluted labyrinth of membranes surrounding organelles. Since the advent of various structural biology techniques, a sub-population of these proteins has become accessible to investigation at near-atomic resolutions. The predominant bona fide methods for structure solution, X-ray crystallography and cryo-EM, provide high resolution in three-dimensional space at the cost of neglecting protein motions through time. Though structures provide various rigid snapshots, only an amorphous mechanistic understanding can be inferred from interpolations between these different static states. In this review, we discuss various techniques that have been utilized in observing dynamic conformational intermediaries that remain elusive from rigid structures. More specifically we discuss the application of structural techniques such as NMR, cryo-EM and X-ray crystallography in studying protein dynamics along with complementation by conformational trapping by specific binders such as antibodies. We finally showcase the strength of various biophysical techniques including FRET, EPR and computational approaches using a multitude of succinct examples from GPCRs, transporters and ion channels.
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Affiliation(s)
- Robbins Puthenveetil
- Section on Structural and Chemical Biology of Membrane Proteins, Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 35A Convent Dr., Bethesda, MD 20892, USA
| | | | - Olga Vinogradova
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA
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12
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Biondi B, Syryamina VN, Rocchio G, Barbon A, Formaggio F, Toniolo C, Raap J, Dzuba SA. Is Cys(MTSL) the Best α-Amino Acid Residue to Electron Spin Labeling of Synthetically Accessible Peptide Molecules with Nitroxides? ACS OMEGA 2022; 7:5154-5165. [PMID: 35187331 PMCID: PMC8851612 DOI: 10.1021/acsomega.1c06227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 12/27/2021] [Indexed: 06/14/2023]
Abstract
Electron paramagnetic resonance spectroscopy, particularly its pulse technique double electron-electron resonance (DEER) (also termed PELDOR), is rapidly becoming an extremely useful tool for the experimental determination of side chain-to-side chain distances between free radicals in molecules fundamental for life, such as polypeptides. Among appropriate probes, the most popular are undoubtedly nitroxide electron spin labels. In this context, suitable biosynthetically derived, helical regions of proteins, along with synthetic peptides with amphiphilic properties and antibacterial activities, are the most extensively investigated compounds. A strict requirement for a precise distance measurement has been identified in a minimal dynamic flexibility of the two nitroxide-bearing α-amino acid side chains. To this end, in this study, we have experimentally compared in detail the side-chain mobility properties of the two currently most widely utilized residues, namely, Cys(MTSL) and 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC). In particular, two double-labeled, chemically synthesized 20-mer peptide molecules have been adopted as appropriate templates for our investigation on the determination of the model intramolecular separations. These double-Cys(MTSL) and double-TOAC compounds are both analogues of the almost completely rigid backbone peptide ruler which we have envisaged and 3D structurally analyzed as our original, unlabeled compound. Here, we have clearly found that the TOAC side-chain labels are largely more 3D structurally restricted than the MTSL labels. From this result, we conclude that the TOAC residue offers more precise information than the Cys(MTSL) residue on the side chain-to-side chain distance distribution in synthetically accessible peptide molecules.
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Affiliation(s)
- Barbara Biondi
- Institute
of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| | - Victoria N. Syryamina
- Institute
of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russian Federation
| | - Gabriele Rocchio
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Antonio Barbon
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Fernando Formaggio
- Institute
of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Claudio Toniolo
- Institute
of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Jan Raap
- Leiden
Institute of Chemistry, Gorlaeus Laboratories,
Leiden University, 2300 RA Leiden, The Netherlands
| | - Sergei A. Dzuba
- Institute
of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russian Federation
- Department
of Physics, Novosibirsk State University, 630090 Novosibirsk, Russian Federation
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13
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Ahammad T, Khan RH, Sahu ID, Drew DL, Faul E, Li T, McCarrick RM, Lorigan GA. Pinholin S 21 mutations induce structural topology and conformational changes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183771. [PMID: 34499883 DOI: 10.1016/j.bbamem.2021.183771] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 08/30/2021] [Accepted: 09/01/2021] [Indexed: 12/23/2022]
Abstract
The bacteriophage infection cycle is terminated at a predefined time to release the progeny virions via a robust lytic system composed of holin, endolysin, and spanin proteins. Holin is the timekeeper of this process. Pinholin S21 is a prototype holin of phage Φ21, which determines the timing of host cell lysis through the coordinated efforts of pinholin and antipinholin. However, mutations in pinholin and antipinholin play a significant role in modulating the timing of lysis depending on adverse or favorable growth conditions. Earlier studies have shown that single point mutations of pinholin S21 alter the cell lysis timing, a proxy for pinholin function as lysis is also dependent on other lytic proteins. In this study, continuous wave electron paramagnetic resonance (CW-EPR) power saturation and double electron-electron resonance (DEER) spectroscopic techniques were used to directly probe the effects of mutations on the structure and conformational changes of pinholin S21 that correlate with pinholin function. DEER and CW-EPR power saturation data clearly demonstrate that increased hydrophilicity induced by residue mutations accelerate the externalization of antipinholin transmembrane domain 1 (TMD1), while increased hydrophobicity prevents the externalization of TMD1. This altered hydrophobicity is potentially accelerating or delaying the activation of pinholin S21. It was also found that mutations can influence intra- or intermolecular interactions in this system, which contribute to the activation of pinholin and modulate the cell lysis timing. This could be a novel approach to analyze the mutational effects on other holin systems, as well as any other membrane protein in which mutation directly leads to structural and conformational changes.
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Affiliation(s)
- Tanbir Ahammad
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Rasal H Khan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA; Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Daniel L Drew
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Emily Faul
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Tianyan Li
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Robert M McCarrick
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA.
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14
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Kaddah S, Khreich N, Kaddah F, Charcosset C, Greige-Gerges H. Pentacyclic triterpenes modulate liposome membrane fluidity and permeability depending on membrane cholesterol content. Int J Pharm 2021; 610:121232. [PMID: 34744000 DOI: 10.1016/j.ijpharm.2021.121232] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 10/05/2021] [Accepted: 10/23/2021] [Indexed: 12/08/2022]
Abstract
Since the membrane-related processes represent an integral part of the biological activities of drugs, their effect on the membrane dynamics is actually considered. In this study, we investigated the effect of pentacyclic triterpenes (TTPs), oleanolic acid (OA) and erythrodiol (ER), on the fluidity and permeability of liposomes membranes differing by their cholesterol content. All liposomes were prepared by reverse phase evaporation technique (REV). Spin-labeled liposomes exposed or not to TTPs were used for fluidity studies by using 5- and 16-doxyl stearic acids (DSA). TTPs-loaded liposomes (phospholipid:cholesterol of 1:1), and preformed vesicles exposed to TTPs were used for permeability studies by monitoring the release of sulforhodamine B (SRB) at 37 °C. The apparent release constants of SRB were determined by Higuchi model based on a biphasic curve shape (0-10 h; 10-48 h). TTPs-loaded liposomes were characterized for their size and homogeneity. Results showed that ER increased the membrane fluidity at the upper region of the membrane while the both TTPs produced a condensing effect at the deeper region of the membrane. The membrane composition was a critical parameter modulating the effect of TTPs on the membrane permeability. Also, this study consolidated the fact that a fluidizing membrane agent is not necessarily a permeabilizing-membrane compound.
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Affiliation(s)
- Samar Kaddah
- Bioactive Molecules Research Laboratory, Faculty of Sciences, Lebanese University, Lebanon; Univ Lyon, Université Claude Bernard Lyon 1, CNRS, LAGEPP UMR 5007, France
| | - Nathalie Khreich
- Bioactive Molecules Research Laboratory, Faculty of Sciences, Lebanese University, Lebanon
| | - Fouad Kaddah
- École Supérieure d'ingénieurs de Beyrouth, Université Saint Joseph, Beyrouth, Mar Roukoz-Dekwaneh, Lebanon
| | | | - Hélène Greige-Gerges
- Bioactive Molecules Research Laboratory, Faculty of Sciences, Lebanese University, Lebanon.
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15
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Zhu S, Kachooei E, Harmer JR, Brown LJ, Separovic F, Sani MA. TOAC spin-labeled peptides tailored for DNP-NMR studies in lipid membrane environments. Biophys J 2021; 120:4501-4511. [PMID: 34480924 DOI: 10.1016/j.bpj.2021.08.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 07/08/2021] [Accepted: 08/10/2021] [Indexed: 12/15/2022] Open
Abstract
The benefit of combining in-cell solid-state dynamic nuclear polarization (DNP) NMR and cryogenic temperatures is providing sufficient signal/noise and preservation of bacterial integrity via cryoprotection to enable in situ biophysical studies of antimicrobial peptides. The radical source required for DNP was delivered into cells by adding a nitroxide-tagged peptide based on the antimicrobial peptide maculatin 1.1 (Mac1). In this study, the structure, localization, and signal enhancement properties of a single (T-MacW) and double (T-T-MacW) TOAC (2,2,6,6-tetramethylpiperidine-N-oxyl-4-amino-4-carboxylic acid) spin-labeled Mac1 analogs were determined within micelles or lipid vesicles. The solution NMR and circular dichroism results showed that the spin-labeled peptides adopted helical structures in contact with micelles. The peptides behaved as an isolated radical source in the presence of multilamellar vesicles, and the electron paramagnetic resonance (EPR) electron-electron distance for the doubly spin-labeled peptide was ∼1 nm. The strongest paramagnetic relaxation enhancement (PRE) was observed for the lipid NMR signals near the glycerol-carbonyl backbone and was stronger for the doubly spin-labeled peptide. Molecular dynamics simulation of the T-T-MacW radical source in phospholipid bilayers supported the EPR and PRE observations while providing further structural insights. Overall, the T-T-MacW peptide achieved better 13C and 15N signal NMR enhancements and 1H spin-lattice T1 relaxation than T-MacW.
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Affiliation(s)
- Shiying Zhu
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Ehsan Kachooei
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Jeffrey R Harmer
- Centre for Advanced Imaging, University of Queensland, Brisbane, Queensland, Australia
| | - Louise J Brown
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia.
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16
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Majeed S, Ahmad AB, Sehar U, Georgieva ER. Lipid Membrane Mimetics in Functional and Structural Studies of Integral Membrane Proteins. MEMBRANES 2021; 11:685. [PMID: 34564502 PMCID: PMC8470526 DOI: 10.3390/membranes11090685] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/18/2021] [Accepted: 08/30/2021] [Indexed: 12/12/2022]
Abstract
Integral membrane proteins (IMPs) fulfill important physiological functions by providing cell-environment, cell-cell and virus-host communication; nutrients intake; export of toxic compounds out of cells; and more. However, some IMPs have obliterated functions due to polypeptide mutations, modifications in membrane properties and/or other environmental factors-resulting in damaged binding to ligands and the adoption of non-physiological conformations that prevent the protein from returning to its physiological state. Thus, elucidating IMPs' mechanisms of function and malfunction at the molecular level is important for enhancing our understanding of cell and organism physiology. This understanding also helps pharmaceutical developments for restoring or inhibiting protein activity. To this end, in vitro studies provide invaluable information about IMPs' structure and the relation between structural dynamics and function. Typically, these studies are conducted on transferred from native membranes to membrane-mimicking nano-platforms (membrane mimetics) purified IMPs. Here, we review the most widely used membrane mimetics in structural and functional studies of IMPs. These membrane mimetics are detergents, liposomes, bicelles, nanodiscs/Lipodisqs, amphipols, and lipidic cubic phases. We also discuss the protocols for IMPs reconstitution in membrane mimetics as well as the applicability of these membrane mimetic-IMP complexes in studies via a variety of biochemical, biophysical, and structural biology techniques.
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Affiliation(s)
- Saman Majeed
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Akram Bani Ahmad
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Ujala Sehar
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Elka R Georgieva
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
- Department of Cell Physiology and Molecular Biophysics, Texas Tech University Health Science Center, Lubbock, TX 79409, USA
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17
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Pan Y, Li H, Li Q, Lenertz M, Schuster I, Jordahl D, Zhu X, Chen B, Yang Z. Protocol for resolving enzyme orientation and dynamics in advanced porous materials via SDSL-EPR. STAR Protoc 2021; 2:100676. [PMID: 34308381 PMCID: PMC8287244 DOI: 10.1016/j.xpro.2021.100676] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Enzyme encapsulation in metal-organic frameworks (MOFs)/covalent-organic frameworks (COFs) provides advancement in biocatalysis, yet the structural basis underlying the catalytic performance is challenging to probe. Here, we present an effective protocol to determine the orientation and dynamics of enzymes in MOFs/COFs using site-directed spin labeling and electron paramagnetic resonance spectroscopy. The protocol is demonstrated using lysozyme and can be generalized to other enzymes. For complete information on the generation and use of this protocol, please refer to Pan et al. (2021a). A protocol to resolve protein orientation/dynamics in porous materials is provided Site-directed spin labeling is combined with electron paramagnetic resonance Principles of protein labeling and key data acquisition steps are summarized Spectral simulation details with troubleshooting procedures are detailed
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Affiliation(s)
- Yanxiong Pan
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58102, USA
| | - Hui Li
- Department of Plant Sciences, North Dakota State University, Fargo, ND 58102, USA
| | - Qiaobin Li
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58102, USA
| | - Mary Lenertz
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58102, USA
| | - Isabelle Schuster
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58102, USA
| | - Drew Jordahl
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58102, USA
| | - Xiao Zhu
- Research Computing, Information Technology at Purdue (ITaP), Purdue University, West Lafayette, IN 47907, USA.,Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Bingcan Chen
- Department of Plant Sciences, North Dakota State University, Fargo, ND 58102, USA
| | - Zhongyu Yang
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58102, USA
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18
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Herr K, Fleckenstein M, Brodrecht M, Höfler MV, Heise H, Aussenac F, Gutmann T, Reggelin M, Buntkowsky G. A novel strategy for site selective spin-labeling to investigate bioactive entities by DNP and EPR spectroscopy. Sci Rep 2021; 11:13714. [PMID: 34211027 PMCID: PMC8249612 DOI: 10.1038/s41598-021-92975-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/18/2021] [Indexed: 11/09/2022] Open
Abstract
A novel specific spin-labeling strategy for bioactive molecules is presented for eptifibatide (integrilin) an antiplatelet aggregation inhibitor, which derives from the venom of certain rattlesnakes. By specifically labeling the disulfide bridge this molecule becomes accessible for analytical techniques such as Electron Paramagnetic Resonance (EPR) and solid state Dynamic Nuclear Polarization (DNP). The necessary spin-label was synthesized and inserted into the disulfide bridge of eptifibatide via reductive followed by insertion by a double Michael addition under physiological conditions. This procedure is universally applicable for disulfide containing biomolecules and is expected to preserve their tertiary structure with minimal change due to the small size of the label and restoring of the previous disulfide connection. HPLC and MS analysis show the successful introduction of the spin label and EPR spectroscopy confirms its activity. DNP-enhanced solid state NMR experiments show signal enhancement factors of up to 19 in 13C CP MAS experiments which corresponds to time saving factors of up to 361. This clearly shows the high potential of our new spin labeling strategy for the introduction of site selective radical spin labels into biomolecules and biosolids without compromising its conformational integrity for structural investigations employing solid-state DNP or advanced EPR techniques.
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Affiliation(s)
- Kevin Herr
- Institute of Physical Chemistry, Technical University Darmstadt, Alarich-Weiss-Straße 8, 64287, Darmstadt, Germany
| | - Max Fleckenstein
- Institute of Organic Chemistry, Technical University Darmstadt, Alarich-Weiss-Straße 4, 64287, Darmstadt, Germany
| | - Martin Brodrecht
- Institute of Physical Chemistry, Technical University Darmstadt, Alarich-Weiss-Straße 8, 64287, Darmstadt, Germany
| | - Mark V Höfler
- Institute of Physical Chemistry, Technical University Darmstadt, Alarich-Weiss-Straße 8, 64287, Darmstadt, Germany
| | - Henrike Heise
- Structural Biochemistry (ICS-6), Institute of Complex Systems, Forschungszentrum Jülich, 52425, Jülich, Germany.,Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - Fabien Aussenac
- Bruker France SAS, 34 rue de l'industrie, 67160, Wissembourg, France
| | - Torsten Gutmann
- Institute of Physical Chemistry, Technical University Darmstadt, Alarich-Weiss-Straße 8, 64287, Darmstadt, Germany
| | - Michael Reggelin
- Institute of Organic Chemistry, Technical University Darmstadt, Alarich-Weiss-Straße 4, 64287, Darmstadt, Germany.
| | - Gerd Buntkowsky
- Institute of Physical Chemistry, Technical University Darmstadt, Alarich-Weiss-Straße 8, 64287, Darmstadt, Germany.
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19
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Probing Structural Dynamics of Membrane Proteins Using Electron Paramagnetic Resonance Spectroscopic Techniques. BIOPHYSICA 2021. [DOI: 10.3390/biophysica1020009] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Membrane proteins are essential for the survival of living organisms. They are involved in important biological functions including transportation of ions and molecules across the cell membrane and triggering the signaling pathways. They are targets of more than half of the modern medical drugs. Despite their biological significance, information about the structural dynamics of membrane proteins is lagging when compared to that of globular proteins. The major challenges with these systems are low expression yields and lack of appropriate solubilizing medium required for biophysical techniques. Electron paramagnetic resonance (EPR) spectroscopy coupled with site directed spin labeling (SDSL) is a rapidly growing powerful biophysical technique that can be used to obtain pertinent structural and dynamic information on membrane proteins. In this brief review, we will focus on the overview of the widely used EPR approaches and their emerging applications to answer structural and conformational dynamics related questions on important membrane protein systems.
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20
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Ahammad T, Drew DL, Sahu ID, Khan RH, Butcher BJ, Serafin RA, Galende AP, McCarrick RM, Lorigan GA. Conformational Differences Are Observed for the Active and Inactive Forms of Pinholin S 21 Using DEER Spectroscopy. J Phys Chem B 2020; 124:11396-11405. [PMID: 33289567 DOI: 10.1021/acs.jpcb.0c09081] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Bacteriophages have evolved with an efficient host cell lysis mechanism to terminate the infection cycle and release the new progeny virions at the optimum time, allowing adaptation with the changing host and environment. Among the lytic proteins, holin controls the first and rate-limiting step of host cell lysis by permeabilizing the inner membrane at an allele-specific time known as "holin triggering". Pinholin S21 is a prototype holin of phage Φ21 which makes many nanoscale holes and destroys the proton motive force, which in turn activates the signal anchor release (SAR) endolysin system to degrade the peptidoglycan layer of the host cell and destruction of the outer membrane by the spanin complex. Like many others, phage Φ21 has two holin proteins: active pinholin and antipinholin. The antipinholin form differs only by three extra amino acids at the N-terminus; however, it has a different structural topology and conformation with respect to the membrane. Predefined combinations of active pinholin and antipinholin fine-tune the lysis timing through structural dynamics and conformational changes. Previously, the dynamics and topology of active pinholin and antipinholin were investigated (Ahammad et al. JPCB 2019, 2020) using continuous wave electron paramagnetic resonance (CW-EPR) spectroscopy. However, detailed structural studies and direct comparison of these two forms of pinholin S21 are absent in the literature. In this study, the structural topology and conformations of active pinholin (S2168) and inactive antipinholin (S2168IRS) in DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) proteoliposomes were investigated using the four-pulse double electron-electron resonance (DEER) EPR spectroscopic technique to measure distances between transmembrane domains 1 and 2 (TMD1 and TMD2). Five sets of interlabel distances were measured via DEER spectroscopy for both the active and inactive forms of pinholin S21. Structural models of the active pinholin and inactive antipinholin forms in DMPC proteoliposomes were obtained using the experimental DEER distances coupled with the simulated annealing software package Xplor-NIH. TMD2 of S2168 remains in the lipid bilayer, and TMD1 is partially externalized from the bilayer with some residues located on the surface. However, both TMDs remain incorporated in the lipid bilayer for the inactive S2168IRS form. This study demonstrates, for the first time, clear structural topology and conformational differences between the two forms of pinholin S21. This work will pave the way for further studies of other holin systems using the DEER spectroscopic technique and will give structural insight into these biological clocks in molecular detail.
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Affiliation(s)
- Tanbir Ahammad
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Daniel L Drew
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States.,Natural Science Division, Campbellsville University, Campbellsville, Kentucky 42718, United States
| | - Rasal H Khan
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Brandon J Butcher
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Rachel A Serafin
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Alberto P Galende
- Natural Science Division, Campbellsville University, Campbellsville, Kentucky 42718, United States
| | - Robert M McCarrick
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
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21
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Yu L, Fang W, He Y, Cai W, Wei W, Tian C. Secondary structure and transmembrane topology analysis of the N-terminal domain of the inner membrane protein EccE 1 from M. smegmatis using site-directed spin labeling EPR. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1863:183515. [PMID: 33245893 DOI: 10.1016/j.bbamem.2020.183515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 10/29/2020] [Accepted: 11/20/2020] [Indexed: 10/22/2022]
Abstract
Protein EccE1 is an essential component of the mycobacterial ESX-1 secretion system, which plays a crucial part in the process of virulence factors secretion, especially for pathogenic mycobacteria such as Mycobacterium tuberculosis. While EccE1 was previously postulated to be the inner membrane pore-forming unit of a membrane complex through which substrates are transported, the structural properties of EccE1 remains to be explored. In the present study, systematic Site-Directed Spin Labeling (SDSL) and Electron Paramagnetic Resonance (EPR) spectroscopic studies was carried out to reveal the secondary structure and transmembrane topology of the N-terminal Domain of EccE1 protein (EccE1-NTD) from M. smegmatis in detergent micelles. EPR-based mobility and accessibility analysis of the R1 side chain for 64 residue positions of EccE1-NTD indicates that the transmembrane domain adopts two α-helices spanning Phe7-Cys30 and Leu36-Ile54. A tentative structural topology model of EccE1-NTD embedded in membrane is also suggested based on EPR spectroscopic data in this study, which will provide further insights into this protein and the ESX secretion systems of mycobacteria.
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Affiliation(s)
- Lu Yu
- High Magnetic Field Laboratory, Chinese Academy of Science, Hefei, Anhui 230031, China.
| | - Wei Fang
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yao He
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Wenguang Cai
- School of Life Sciences, Anhui University, 111 Jiulong Road, Hefei, Anhui 230601, China
| | - Wei Wei
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Changlin Tian
- High Magnetic Field Laboratory, Chinese Academy of Science, Hefei, Anhui 230031, China; Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China.
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22
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Georgieva ER. Protein Conformational Dynamics upon Association with the Surfaces of Lipid Membranes and Engineered Nanoparticles: Insights from Electron Paramagnetic Resonance Spectroscopy. Molecules 2020; 25:E5393. [PMID: 33218036 PMCID: PMC7698768 DOI: 10.3390/molecules25225393] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 11/15/2020] [Accepted: 11/16/2020] [Indexed: 11/16/2022] Open
Abstract
Detailed study of conformational rearrangements and dynamics of proteins is central to our understanding of their physiological functions and the loss of function. This review outlines the applications of the electron paramagnetic resonance (EPR) technique to study the structural aspects of proteins transitioning from a solution environment to the states in which they are associated with the surfaces of biological membranes or engineered nanoobjects. In the former case these structural transitions generally underlie functional protein states. The latter case is mostly relevant to the application of protein immobilization in biotechnological industries, developing methods for protein purification, etc. Therefore, evaluating the stability of the protein functional state is particularly important. EPR spectroscopy in the form of continuous-wave EPR or pulse EPR distance measurements in conjunction with protein spin labeling provides highly versatile and sensitive tools to characterize the changes in protein local dynamics as well as large conformational rearrangements. The technique can be widely utilized in studies of both protein-membrane and engineered nanoobject-protein complexes.
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Affiliation(s)
- Elka R Georgieva
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
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23
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Murakami K, Yamaguchi T, Izuo N, Kume T, Hara H, Irie K. Synthetic and Biophysical Studies on the Toxic Conformer in Amyloid β with the E22Δ Mutation in Alzheimer Pathology. ACS Chem Neurosci 2020; 11:3017-3024. [PMID: 32790274 DOI: 10.1021/acschemneuro.0c00331] [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] [Indexed: 12/15/2022] Open
Abstract
The toxic conformer of the 40- or 42-mer-amyloid β-proteins (Aβ) (Aβ40, Aβ42) with a turn at positions 22 and 23 plays a role in oligomer formation, leading to neurotoxicity as part of the pathogenesis of Alzheimer's disease (AD). A deletion mutant at Glu22 (E22Δ) of Aβ, known as an Osaka mutation, accelerates oligomerization. Although E22Δ-Aβ has not been found to be toxic to cultured neuronal cells and is instead synaptotoxic in long-term potentiation, there is no information on the toxic conformer of E22Δ-Aβ in AD. The site-directed spin labeling study of E22Δ-Aβ40 by continuous wave-electron spin resonance (CW-ESR) spectroscopy in part showed the spatial proximity between positions 10 and 35, which are characteristic of the toxic conformation of Aβ, indicating the existence of a toxic conformer of Aβ with the E22Δ mutation. To obtain structural insight, E22Δ-Aβ42 substitutes with proline (F20P, A21P, D23P, and V24P), in which proline is known as a turn inducer but is a β-sheet breaker, were synthesized. An enzyme immunoassay using the 24B3 antibody recognizing toxic conformer of Aβ was carried out. 24B3 reacted with these substitutes of E22Δ-Aβ42 as well as E22Δ-Aβ42 in a similar manner to WT-Aβ42. Notably, only A21P-E22Δ-Aβ42 exhibited strong neurotoxicity in rat primary neurons after 8 days of incubation, with potent high-order oligomerization compared with E22Δ-Aβ42. These results suggest that E22Δ-Aβ42 could enhance neurotoxicity by generating a toxic oligomer conformation with a turn near position 21.
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Affiliation(s)
- Kazuma Murakami
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Tomomi Yamaguchi
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Naotaka Izuo
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Toshiaki Kume
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Hideyuki Hara
- BioSpin Division, Bruker Japan K. K., Yokohama 221-0022, Japan
| | - Kazuhiro Irie
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
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24
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Poncelet M, Driesschaert B. A 13 C-Labeled Triarylmethyl Radical as an EPR Spin Probe Highly Sensitive to Molecular Tumbling. Angew Chem Int Ed Engl 2020; 59:16451-16454. [PMID: 32542924 PMCID: PMC7901239 DOI: 10.1002/anie.202006591] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Indexed: 12/21/2022]
Abstract
A stable triarylmethyl spin probe whose electron paramagnetic resonance (EPR) spectrum is highly sensitive to molecular tumbling is reported. The strong anisotropy of the hyperfine coupling tensor with the central carbon of a 13 C1 -labeled triarylmethyl radical enables the measurement of the probe rotational correlation time with applications to measure microviscosity and molecular dynamics.
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Affiliation(s)
- Martin Poncelet
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, WV, 26506, USA
- In Vivo Multifunctional Magnetic Resonance Center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV, 26506, USA
| | - Benoit Driesschaert
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, WV, 26506, USA
- In Vivo Multifunctional Magnetic Resonance Center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV, 26506, USA
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25
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Ahammad T, Drew DL, Khan RH, Sahu ID, Faul E, Li T, Lorigan GA. Structural Dynamics and Topology of the Inactive Form of S 21 Holin in a Lipid Bilayer Using Continuous-Wave Electron Paramagnetic Resonance Spectroscopy. J Phys Chem B 2020; 124:5370-5379. [PMID: 32501696 DOI: 10.1021/acs.jpcb.0c03575] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The bacteriophage infection cycle plays a crucial role in recycling the world's biomass. Bacteriophages devise various cell lysis systems to strictly control the length of the infection cycle for an efficient phage life cycle. Phages evolved with lysis protein systems, which can control and fine-tune the length of this infection cycle depending on the host and growing environment. Among these lysis proteins, holin controls the first and rate-limiting step of host cell lysis by permeabilizing the inner membrane at an allele-specific time and concentration hence known as the simplest molecular clock. Pinholin S21 is the holin from phage Φ21, which defines the cell lysis time through a predefined ratio of active pinholin and antipinholin (inactive form of pinholin). Active pinholin and antipinholin fine-tune the lysis timing through structural dynamics and conformational changes. Previously we reported the structural dynamics and topology of active pinholin S2168. Currently, there is no detailed structural study of the antipinholin using biophysical techniques. In this study, the structural dynamics and topology of antipinholin S2168IRS in DMPC proteoliposomes is investigated using electron paramagnetic resonance (EPR) spectroscopic techniques. Continuous-wave (CW) EPR line shape analysis experiments of 35 different R1 side chains of S2168IRS indicated restricted mobility of the transmembrane domains (TMDs), which were predicted to be inside the lipid bilayer when compared to the N- and C-termini R1 side chains. In addition, the R1 accessibility test performed on 24 residues using the CW-EPR power saturation experiment indicated that TMD1 and TMD2 of S2168IRS were incorporated into the lipid bilayer where N- and C-termini were located outside of the lipid bilayer. Based on this study, a tentative model of S2168IRS is proposed where both TMDs remain incorporated into the lipid bilayer and N- and C-termini are located outside of the lipid bilayer. This work will pave the way for the further studies of other holins using biophysical techniques and will give structural insights into these biological clocks in molecular detail.
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Affiliation(s)
- Tanbir Ahammad
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Daniel L Drew
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Rasal H Khan
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States.,Natural Science Division, Campbellsville University, Campbellsville, Kentucky 42718, United States
| | - Emily Faul
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Tianyan Li
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
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26
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Sahu ID, Lorigan GA. Electron Paramagnetic Resonance as a Tool for Studying Membrane Proteins. Biomolecules 2020; 10:E763. [PMID: 32414134 PMCID: PMC7278021 DOI: 10.3390/biom10050763] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 04/24/2020] [Accepted: 04/24/2020] [Indexed: 12/13/2022] Open
Abstract
Membrane proteins possess a variety of functions essential to the survival of organisms. However, due to their inherent hydrophobic nature, it is extremely difficult to probe the structure and dynamic properties of membrane proteins using traditional biophysical techniques, particularly in their native environments. Electron paramagnetic resonance (EPR) spectroscopy in combination with site-directed spin labeling (SDSL) is a very powerful and rapidly growing biophysical technique to study pertinent structural and dynamic properties of membrane proteins with no size restrictions. In this review, we will briefly discuss the most commonly used EPR techniques and their recent applications for answering structure and conformational dynamics related questions of important membrane protein systems.
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Affiliation(s)
- Indra D. Sahu
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Gary A. Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
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27
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Sahu ID, Dixit G, Reynolds WD, Kaplevatsky R, Harding BD, Jaycox CK, McCarrick RM, Lorigan GA. Characterization of the Human KCNQ1 Voltage Sensing Domain (VSD) in Lipodisq Nanoparticles for Electron Paramagnetic Resonance (EPR) Spectroscopic Studies of Membrane Proteins. J Phys Chem B 2020; 124:2331-2342. [PMID: 32130007 DOI: 10.1021/acs.jpcb.9b11506] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Membrane proteins are responsible for conducting essential biological functions that are necessary for the survival of living organisms. In spite of their physiological importance, limited structural information is currently available as a result of challenges in applying biophysical techniques for studying these protein systems. Electron paramagnetic resonance (EPR) spectroscopy is a very powerful technique to study the structural and dynamic properties of membrane proteins. However, the application of EPR spectroscopy to membrane proteins in a native membrane-bound state is extremely challenging due to the complexity observed in inhomogeneity sample preparation and the dynamic motion of the spin label. Detergent micelles are very popular membrane mimetics for membrane proteins due to their smaller size and homogeneity, providing high-resolution structure analysis by solution NMR spectroscopy. However, it is important to test whether the protein structure in a micelle environment is the same as that of its membrane-bound state. Lipodisq nanoparticles or styrene-maleic acid copolymer-lipid nanoparticles (SMALPs) have been introduced as a potentially good membrane-mimetic system for structural studies of membrane proteins. Recently, we reported on the EPR characterization of the KCNE1 membrane protein having a single transmembrane incorporated into lipodisq nanoparticles. In this work, lipodisq nanoparticles were used as a membrane mimic system for probing the structural and dynamic properties of the more complicated membrane protein system human KCNQ1 voltage sensing domain (Q1-VSD) having four transmembrane helices using site-directed spin-labeling EPR spectroscopy. Characterization of spin-labeled Q1-VSD incorporated into lipodisq nanoparticles was carried out using CW-EPR spectral line shape analysis and pulsed EPR double-electron electron resonance (DEER) measurements. The CW-EPR spectra indicate an increase in spectral line broadening with the addition of the styrene-maleic acid (SMA) polymer which approaches close to the rigid limit providing a homogeneous stabilization of the protein-lipid complex. Similarly, EPR DEER measurements indicated a superior quality of distance measurement with an increase in the phase memory time (Tm) values upon incorporation of the sample into lipodisq nanoparticles when compared to proteoliposomes. These results are consistent with the solution NMR structural studies on the Q1-VSD. This study will be beneficial for researchers working on investigating the structural and dynamic properties of more complicated membrane protein systems using lipodisq nanoparticles.
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Affiliation(s)
- Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States.,Natural Science Division, Campbellsville University, Campbellsville, Kentucky 42718, United States
| | - Gunjan Dixit
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Warren D Reynolds
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Ryan Kaplevatsky
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Benjamin D Harding
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Colleen K Jaycox
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Robert M McCarrick
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
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28
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Del Alamo D, Tessmer MH, Stein RA, Feix JB, Mchaourab HS, Meiler J. Rapid Simulation of Unprocessed DEER Decay Data for Protein Fold Prediction. Biophys J 2020; 118:366-375. [PMID: 31892409 PMCID: PMC6976798 DOI: 10.1016/j.bpj.2019.12.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 11/13/2019] [Accepted: 12/04/2019] [Indexed: 01/02/2023] Open
Abstract
Despite advances in sampling and scoring strategies, Monte Carlo modeling methods still struggle to accurately predict de novo the structures of large proteins, membrane proteins, or proteins of complex topologies. Previous approaches have addressed these shortcomings by leveraging sparse distance data gathered using site-directed spin labeling and electron paramagnetic resonance spectroscopy to improve protein structure prediction and refinement outcomes. However, existing computational implementations entail compromises between coarse-grained models of the spin label that lower the resolution and explicit models that lead to resource-intense simulations. These methods are further limited by their reliance on distance distributions, which are calculated from a primary refocused echo decay signal and contain uncertainties that may require manual refinement. Here, we addressed these challenges by developing RosettaDEER, a scoring method within the Rosetta software suite capable of simulating double electron-electron resonance spectroscopy decay traces and distance distributions between spin labels fast enough to fold proteins de novo. We demonstrate that the accuracy of resulting distance distributions match or exceed those generated by more computationally intensive methods. Moreover, decay traces generated from these distributions recapitulate intermolecular background coupling parameters even when the time window of data collection is truncated. As a result, RosettaDEER can discriminate between poorly folded and native-like models by using decay traces that cannot be accurately converted into distance distributions using regularized fitting approaches. Finally, using two challenging test cases, we demonstrate that RosettaDEER leverages these experimental data for protein fold prediction more effectively than previous methods. These benchmarking results confirm that RosettaDEER can effectively leverage sparse experimental data for a wide array of modeling applications built into the Rosetta software suite.
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Affiliation(s)
- Diego Del Alamo
- Department of Chemistry and Center for Structural Biology; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | | | - Richard A Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Jimmy B Feix
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Hassane S Mchaourab
- Department of Chemistry and Center for Structural Biology; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Jens Meiler
- Department of Chemistry and Center for Structural Biology; Institut for Drug Discovery, Leipzig University, Leipzig, Germany.
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29
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Vuong W, Mosquera-Guagua F, Sanichar R, McDonald TR, Ernst OP, Wang L, Vederas JC. Synthesis of Chiral Spin-Labeled Amino Acids. Org Lett 2019; 21:10149-10153. [DOI: 10.1021/acs.orglett.9b04216] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wayne Vuong
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | | | - Randy Sanichar
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | - Tyler R. McDonald
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | - Oliver P. Ernst
- Departments of Biochemistry & Molecular Genetics, University of Toronto, Toronto, ON, Canada M5S 1A8
| | - Lei Wang
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, United States
| | - John C. Vederas
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
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30
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Bondarenko V, Wells MM, Chen Q, Singewald KC, Saxena S, Xu Y, Tang P. 19F Paramagnetic Relaxation-Based NMR for Quaternary Structural Restraints of Ion Channels. ACS Chem Biol 2019; 14:2160-2165. [PMID: 31525026 DOI: 10.1021/acschembio.9b00692] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Quaternary distance restraints are essential to define the three-dimensional structures of protein assemblies. These distances often fall within a range of 10-18 Å, which challenges the high and low measurement limits of conventional nuclear magnetic resonance (NMR) and double electron-electron resonance electron spin resonance spectroscopies. Here, we report the use of 19F paramagnetic relaxation enhancement (PRE) NMR in combination with 19F/paramagnetic labeling to equivalent sites in different subunits of a protein complex in micelles to determine intersubunit distances. The feasibility of this strategy was evaluated on a pentameric ligand-gated ion channel, for which we found excellent agreement of the 19F PRE NMR results with previous structural information. The study suggests that 19F PRE NMR is a viable tool in extracting distance restraints to define quaternary structures.
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Affiliation(s)
- Vasyl Bondarenko
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Marta M. Wells
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Qiang Chen
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Kevin C. Singewald
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Yan Xu
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Structural Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Pei Tang
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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31
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Ahammad T, Drew DL, Sahu ID, Serafin RA, Clowes KR, Lorigan GA. Continuous Wave Electron Paramagnetic Resonance Spectroscopy Reveals the Structural Topology and Dynamic Properties of Active Pinholin S 2168 in a Lipid Bilayer. J Phys Chem B 2019; 123:8048-8056. [PMID: 31478671 DOI: 10.1021/acs.jpcb.9b06480] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Pinholin S2168 is an essential part of the phage Φ21 lytic protein system to release the virus progeny at the end of the infection cycle. It is known as the simplest natural timing system for its precise control of hole formation in the inner cytoplasmic membrane. Pinholin S2168 is a 68 amino acid integral membrane protein consisting of two transmembrane domains (TMDs) called TMD1 and TMD2. Despite its biological importance, structural and dynamic information of the S2168 protein in a membrane environment is not well understood. Systematic site-directed spin labeling and continuous wave electron paramagnetic resonance (CW-EPR) spectroscopic studies of pinholin S2168 in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) proteoliposomes are used to reveal the structural topology and dynamic properties in a native-like environment. CW-EPR spectral line-shape analysis of the R1 side chain for 39 residue positions of S2168 indicates that the TMDs have more restricted mobility when compared to the N- and C-termini. CW-EPR power saturation data indicate that TMD1 partially externalizes from the lipid bilayer and interacts with the membrane surface, whereas TMD2 remains buried in the lipid bilayer in the active conformation of pinholin S2168. A tentative structural topology model of pinholin S2168 is also suggested based on EPR spectroscopic data reported in this study.
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Affiliation(s)
- Tanbir Ahammad
- Department of Chemistry and Biochemistry , Miami University , Oxford , Ohio 45056 , United States
| | - Daniel L Drew
- Department of Chemistry and Biochemistry , Miami University , Oxford , Ohio 45056 , United States
| | - Indra D Sahu
- Department of Chemistry and Biochemistry , Miami University , Oxford , Ohio 45056 , United States
| | - Rachel A Serafin
- Department of Chemistry and Biochemistry , Miami University , Oxford , Ohio 45056 , United States
| | - Katherine R Clowes
- Department of Chemistry and Biochemistry , Miami University , Oxford , Ohio 45056 , United States
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry , Miami University , Oxford , Ohio 45056 , United States
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32
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Ding Y, Kathiresan V, Zhang X, Haworth IS, Qin PZ. Experimental Validation of the ALLNOX Program for Studying Protein-Nucleic Acid Complexes. J Phys Chem A 2019; 123:3592-3598. [PMID: 30978022 DOI: 10.1021/acs.jpca.9b01027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Measurement of distances between spectroscopic labels (e.g., spin labels, fluorophores) attached to specific sites of biomolecules is an important method for studying biomolecular complexes. ALLNOX (Addition of Labels and Linkers) has been developed as a program to model interlabel distances based on an input macromolecule structure. Here, we report validation of ALLNOX using measured distances between nitroxide spin labels attached to specific sites of a protein-DNA complex. The results demonstrate that ALLNOX predicts average interspin distances that matched with values measured with pairs of labels attached at the protein and/or DNA. This establishes a solid foundation for using spin labeling in conjunction with ALLNOX to investigate complexes without high-resolution structures. With its high degree of flexibility for the label or the target biomolecule, ALLNOX provides a useful tool for investigating the structure-function relationship in a large variety of biological molecules.
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Affiliation(s)
- Yuan Ding
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - Venkatesan Kathiresan
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - Xiaojun Zhang
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - Ian S Haworth
- Department of Pharmacology and Pharmaceutical Sciences , University of Southern California , Los Angeles , California 90089 , United States
| | - Peter Z Qin
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States.,Department of Biological Sciences , University of Southern California , Los Angeles , California 90089 , United States
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33
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Bolla JR, Agasid MT, Mehmood S, Robinson CV. Membrane Protein-Lipid Interactions Probed Using Mass Spectrometry. Annu Rev Biochem 2019; 88:85-111. [PMID: 30901263 DOI: 10.1146/annurev-biochem-013118-111508] [Citation(s) in RCA: 125] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Membrane proteins that exist in lipid bilayers are not isolated molecular entities. The lipid molecules that surround them play crucial roles in maintaining their full structural and functional integrity. Research directed at investigating these critical lipid-protein interactions is developing rapidly. Advancements in both instrumentation and software, as well as in key biophysical and biochemical techniques, are accelerating the field. In this review, we provide a brief outline of structural techniques used to probe protein-lipid interactions and focus on the molecular aspects of these interactions obtained from native mass spectrometry (native MS). We highlight examples in which lipids have been shown to modulate membrane protein structure and show how native MS has emerged as a complementary technique to X-ray crystallography and cryo-electron microscopy. We conclude with a short perspective on future developments that aim to better understand protein-lipid interactions in the native environment.
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Affiliation(s)
- Jani Reddy Bolla
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, United Kingdom;
| | - Mark T Agasid
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, United Kingdom;
| | - Shahid Mehmood
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, United Kingdom;
| | - Carol V Robinson
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, United Kingdom;
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34
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Bali AP, Sahu ID, Craig AF, Clark EE, Burridge KM, Dolan MT, Dabney-Smith C, Konkolewicz D, Lorigan GA. Structural characterization of styrene-maleic acid copolymer-lipid nanoparticles (SMALPs) using EPR spectroscopy. Chem Phys Lipids 2019; 220:6-13. [PMID: 30796886 DOI: 10.1016/j.chemphyslip.2019.02.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 01/29/2019] [Accepted: 02/18/2019] [Indexed: 12/31/2022]
Abstract
Spectroscopic studies of membrane proteins (MPs) are challenging due to difficulties in preparing homogenous and functional lipid membrane mimetic systems into which membrane proteins can properly fold and function. It has recently been shown that styrene-maleic acid (SMA) copolymers act as a macromolecular surfactant and therefore facilitate the formation of disk-shaped lipid bilayer nanoparticles (styrene-maleic acid copolymer-lipid nanoparticles (SMALPs)) that retain structural characteristics of native lipid membranes. We have previously reported controlled synthesis of SMA block copolymers using reversible addition-fragmentation chain transfer (RAFT) polymerization, and that alteration of the weight ratio of styrene to maleic acid affects nanoparticle size. RAFT-synthesis offers superior control over SMA polymer architecture compared to conventional radical polymerization techniques used for commercially available SMA. However, the interactions between the lipid bilayer and the solubilized RAFT-synthesized SMA polymer are currently not fully understood. In this study, EPR spectroscopy was used to detect the perturbation on the acyl chain upon introduction of the RAFT-synthesized SMA polymer by attaching PC-based nitroxide spin labels to the 5th, 12th, and 16th positions along the acyl chain of the lipid bilayer. EPR spectra showed high rigidity at the 12th position compared to the other two regions, displaying similar qualities to commercially available polymers synthesized via conventional methods. In addition, central EPR linewidths and correlation time data were obtained that are consistent with previous findings.
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Affiliation(s)
- Avnika P Bali
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Andrew F Craig
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Emily E Clark
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Kevin M Burridge
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Madison T Dolan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Carole Dabney-Smith
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Dominik Konkolewicz
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA.
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA.
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35
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Smith DJ, Klauda JB, Sodt AJ. Simulation Best Practices for Lipid Membranes [Article v1.0]. LIVING JOURNAL OF COMPUTATIONAL MOLECULAR SCIENCE 2019; 1:5966. [PMID: 36204133 PMCID: PMC9534443 DOI: 10.33011/livecoms.1.1.5966] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/06/2023]
Abstract
We establish a reliable and robust standardization of settings for practical molecular dynamics (MD) simulations of pure and mixed (single- and multi-component) lipid bilayer membranes. In lipid membranes research, particle-based molecular simulations are a powerful tool alongside continuum theory, lipidomics, and model, in vitro, and in vivo experiments. Molecular simulations can provide precise and reproducible spatiotemporal (atomic- and femtosecond-level) information about membrane structure, mechanics, thermodynamics, kinetics, and dynamics. Yet the simulation of lipid membranes can be a daunting task, given the uniqueness of lipid membranes relative to conventional liquid-liquid and solid-liquid interfaces, the immense and complex thermodynamic and statistical mechanical theory, the diversity of multiscale lipid models, limitations of modern computing power, the difficulty and ambiguity of simulation controls, finite size effects, competitive continuum simulation alternatives, and the desired application, including vesicle experiments and biological membranes. These issues can complicate an essential understanding of the field of lipid membranes, and create major bottlenecks to simulation advancement. In this article, we clarify these issues and present a consistent, thorough, and user-friendly framework for the design of state-of-the-art lipid membrane MD simulations. We hope to allow early-career researchers to quickly overcome common obstacles in the field of lipid membranes and reach maximal impact in their simulations.
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Affiliation(s)
- David J. Smith
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA, USA
| | - Jeffery B. Klauda
- Department of Chemical and Biomolecular Engineering and Biophysics Program, University of Maryland, College Park, MD, USA
| | - Alexander J. Sodt
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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36
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Drew DL, Ahammad T, Serafin RA, Butcher BJ, Clowes KR, Drake Z, Sahu ID, McCarrick RM, Lorigan GA. Solid phase synthesis and spectroscopic characterization of the active and inactive forms of bacteriophage S 21 pinholin protein. Anal Biochem 2018; 567:14-20. [PMID: 30528914 DOI: 10.1016/j.ab.2018.12.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 11/29/2018] [Accepted: 12/03/2018] [Indexed: 01/06/2023]
Abstract
The mechanism for the lysis pathway of double-stranded DNA bacteriophages involves a small hole-forming class of membrane proteins, the holins. This study focuses on a poorly characterized class of holins, the pinholin, of which the S21 protein of phage ϕ21 is the prototype. Here we report the first in vitro synthesis of the wildtype form of the S21 pinholin, S2168, and negative-dominant mutant form, S21IRS, both prepared using solid phase peptide synthesis and studied using biophysical techniques. Both forms of the pinholin were labeled with a nitroxide spin label and successfully incorporated into both bicelles and multilamellar vesicles which are membrane mimetic systems. Circular dichroism revealed the two forms were both >80% alpha helical, in agreement with the predictions based on the literature. The molar ellipticity ratio [θ]222/[θ]208 for both forms of the pinholin was 1.4, suggesting a coiled-coil tertiary structure in the bilayer consistent with the proposed oligomerization step in models for the mechanism of hole formation. 31P solid-state NMR spectroscopic data on pinholin indicate a strong interaction of both forms of the pinholin with the membrane headgroups. The 31P NMR data has an axially symmetric line shape which is consistent with lamellar phase proteoliposomes lipid mimetics.
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Affiliation(s)
- Daniel L Drew
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Tanbir Ahammad
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Rachel A Serafin
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Brandon J Butcher
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Katherine R Clowes
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Zachary Drake
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Robert M McCarrick
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, 45056, USA.
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