1
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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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2
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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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3
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A photoswitchable helical peptide with light-controllable interface/transmembrane topology in lipidic membranes. iScience 2021; 24:102771. [PMID: 34286233 PMCID: PMC8273423 DOI: 10.1016/j.isci.2021.102771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 06/02/2021] [Accepted: 06/19/2021] [Indexed: 11/21/2022] Open
Abstract
The spontaneous insertion of helical transmembrane (TM) polypeptides into lipid bilayers is driven by three sequential equilibria: solution-to-membrane interface (MI) partition, unstructured-to-helical folding, and MI-to-TM helix insertion. A bottleneck for understanding these three steps is the lack of experimental approaches to perturb membrane-bound hydrophobic polypeptides out of equilibrium rapidly and reversibly. Here, we report on a 24-residues-long hydrophobic α-helical polypeptide, covalently coupled to an azobenzene photoswitch (KCALP-azo), which displays a light-controllable TM/MI equilibrium in hydrated lipid bilayers. FTIR spectroscopy reveals that trans KCALP-azo folds as a TM α-helix (TM topology). After trans-to-cis photoisomerization of the azobenzene moiety with UV light (reversed with blue light), the helical structure of KCALP-azo is maintained, but its helix tilt increased from 32 ± 5° to 79 ± 8°, indication of a reversible TM-to-MI transition. Further analysis indicates that this transition is incomplete, with cis KCALP-azo existing in a ∼90% TM and ∼10% MI mixture. We present an α-helical transmembrane peptide modified with a molecular photoswitch The peptide exhibits reversible photocontrol of its membrane topology A fraction moves to the membrane interface with UV and inserts back with blue light This system will be useful to address the molecular mechanism for membrane insertion
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Tkach I, Diederichsen U, Bennati M. Studies of transmembrane peptides by pulse dipolar spectroscopy with semi-rigid TOPP spin labels. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2021; 50:143-157. [PMID: 33640998 PMCID: PMC8071797 DOI: 10.1007/s00249-021-01508-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 01/25/2021] [Accepted: 01/29/2021] [Indexed: 12/01/2022]
Abstract
Electron paramagnetic resonance (EPR)-based pulsed dipolar spectroscopy measures the dipolar interaction between paramagnetic centers that are separated by distances in the range of about 1.5-10 nm. Its application to transmembrane (TM) peptides in combination with modern spin labelling techniques provides a valuable tool to study peptide-to-lipid interactions at a molecular level, which permits access to key parameters characterizing the structural adaptation of model peptides incorporated in natural membranes. In this mini-review, we summarize our approach for distance and orientation measurements in lipid environment using novel semi-rigid TOPP [4-(3,3,5,5-tetramethyl-2,6-dioxo-4-oxylpiperazin-1-yl)-L-phenylglycine] labels specifically designed for incorporation in TM peptides. TOPP labels can report single peak distance distributions with sub-angstrom resolution, thus offering new capabilities for a variety of TM peptide investigations, such as monitoring of various helix conformations or measuring of tilt angles in membranes.
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Affiliation(s)
- Igor Tkach
- Max Planck Institute for Biophysical Chemistry, RG Electron-Spin Resonance Spectroscopy, 37077, Göttingen, Germany.
| | - Ulf Diederichsen
- Department of Organic and Biomolecular Chemistry, University of Göttingen, 37077, Göttingen, Germany
| | - Marina Bennati
- Max Planck Institute for Biophysical Chemistry, RG Electron-Spin Resonance Spectroscopy, 37077, Göttingen, Germany
- Department of Organic and Biomolecular Chemistry, University of Göttingen, 37077, Göttingen, Germany
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5
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Golysheva EA, Boyle AL, Biondi B, Ruzza P, Kros A, Raap J, Toniolo C, Formaggio F, Dzuba SA. Probing the E/K Peptide Coiled-Coil Assembly by Double Electron-Electron Resonance and Circular Dichroism. Biochemistry 2020; 60:19-30. [PMID: 33320519 DOI: 10.1021/acs.biochem.0c00773] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Double electron-electron resonance (DEER, also known as PELDOR) and circular dichroism (CD) spectroscopies were explored for the purpose of studying the specificity of the conformation of peptides induced by their assembly into a self-recognizing system. The E and K peptides are known to form a coiled-coil heterodimer. Two paramagnetic TOAC α-amino acid residues were incorporated into each of the peptides (denoted as K** and E**), and a three-dimensional structural investigation in the presence or absence of their unlabeled counterparts E and K was performed. The TOAC spin-labels, replacing two Ala residues in each compound, are covalently and quasi-rigidly connected to the peptide backbone. They are known not to disturb the native structure, so that any conformational change can easily be monitored and assigned. DEER spectroscopy enables the measurement of the intramolecular electron spin-spin distance distribution between the two TOAC labels, within a length range of 1.5-8 nm. This method allows the individual conformational changes for the K**, K**/E, E**, and E**/K molecules to be investigated in glassy frozen solutions. Our data reveal that the conformations of the E** and K** peptides are strongly influenced by the presence of their counterparts. The results are discussed with those from CD spectroscopy and with reference to the already reported nuclear magnetic resonance data. We conclude that the combined DEER/TOAC approach allows us to obtain accurate and reliable information about the conformation of the peptides before and after their assembly into coiled-coil heterodimers. Applications of this induced fit method to other two-component, but more complex, systems, like a receptor and antagonists, a receptor and a hormone, and an enzyme and a ligand, are discussed.
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Affiliation(s)
- Elena A Golysheva
- Novosibirsk State University, Novosibirsk 630090, Russian Federation.,V. V. Voevodsky Institute of Chemical Kinetics and Combustion, Novosibirsk 630090, Russian Federation
| | - Aimee L Boyle
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Barbara Biondi
- Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy.,Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Paolo Ruzza
- Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy.,Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Alexander Kros
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Jan Raap
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Claudio Toniolo
- Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy.,Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.,Department of Chemistry, 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
| | - Sergei A Dzuba
- Novosibirsk State University, Novosibirsk 630090, Russian Federation.,V. V. Voevodsky Institute of Chemical Kinetics and Combustion, Novosibirsk 630090, Russian Federation
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6
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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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7
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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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8
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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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9
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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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10
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Miranda C, Booth VK, Morrow MR. Effects of Amphipathic Polypeptides on Membrane Organization Inferred from Studies Using Bicellar Lipid Mixtures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:11759-11771. [PMID: 30196696 DOI: 10.1021/acs.langmuir.8b02257] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
SP-B63-78, a lung surfactant protein fragment, and magainin 2, an antimicrobial peptide, are amphipathic peptides with the same overall charge but different biological functions. Deuterium nuclear magnetic resonance has been used to compare the interactions of these peptides with dispersions of 1,2-dimyristoyl- sn-glycero-3-phophocholine (DMPC)/1,2-dihexanoyl- sn-glycero-3-phophocholine (DHPC) (4:1) and DMPC/1,2-dimyristoyl- sn-glycero-3-phopho-(1'-rac-glycerol) (DMPG)/DHPC (3:1:1), two mixtures of long-chain and short-chain lipids that display bicellar behavior. This study exploited the sensitivity of a bicellar system structural organization to factors that modify partitioning of their lipid components between different environments. In small bicelle particles formed at low temperatures, short-chain components preferentially occupy curved rim environments around bilayer disks of the long-chain components. Changes in chain order and lipid mixing, on heating, can drive transitions to more extended assemblies including a magnetically orientable phase at intermediate temperature. In this work, neither peptide had a substantial effect on the behavior of the zwitterionic DMPC/DHPC mixture. For bicellar mixtures containing the anionic lipid DMPG, the peptide SP-B63-78 lowered the temperature at which magnetically orientable particles coalesced into more extended lamellar structures. SP-B63-78 did not promote partitioning of the zwitterionic and anionic long-chain lipid components into different environments. Magainin 2, on the other hand, was found to promote separation of the anionic lipid, DMPG, and the zwitterionic lipid, DMPC, into different environments for temperatures above 34 °C. The contrast between the effects of these two peptides on the lipid mixtures studied appears to be consistent with their functional roles in biological systems.
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Affiliation(s)
- Chris Miranda
- Department of Physics and Physical Oceanography , Memorial University of Newfoundland , St. John's , Newfoundland and Labrador , Canada A1B 3X7
| | - Valerie K Booth
- Department of Biochemistry , Memorial University of Newfoundland , St. John's , Newfoundland and Labrador , Canada A1B 3X9
| | - Michael R Morrow
- Department of Physics and Physical Oceanography , Memorial University of Newfoundland , St. John's , Newfoundland and Labrador , Canada A1B 3X7
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