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Yamamoto R, Segawa R, Kato H, Niino Y, Sato T, Hiratsuka M, Hirasawa N. Identification of amino acids in transmembrane domains of mutated cytokine receptor-like factor 2 and interleukin-7 receptor α required for constitutive signal transduction. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184359. [PMID: 38862034 DOI: 10.1016/j.bbamem.2024.184359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 05/25/2024] [Accepted: 06/05/2024] [Indexed: 06/13/2024]
Abstract
Cytokine receptor-like factor 2 (CRLF2) and interleukin-7 receptor α (IL-7Rα) form a receptor for thymic stromal lymphopoietin (TSLP). A somatic mutation consisting of the substitution of five amino acids (SLLLL) in the transmembrane domain of CRLF2 with three amino acids, including glutamic acid, isoleucine, and methionine (insEIM), which has been identified in acute lymphocytic leukemia, causes the TSLP-independent dimerization with IL-7Rα and activation. However, the dimerization mechanism remains unclear. In this study, we examined the involvement of the amino acids in the transmembrane domains of EIM CRLF2 and IL-7Rα in TSLP-independent activation. HEK293 cells were transfected with vectors encoding CRLF2 and IL-7Rα, or their mutants, in which the amino acid of the transmembrane domain was replaced with alanine. STAT5 phosphorylation was detected using western blotting, and receptor dimerization was analyzed using the NanoBiT assay. The substitution of glutamic acid within the insEIM mutation for alanine failed to cause the STAT5 phosphorylation in the absence of TSLP. Moreover, the alanine substation of the specific leucine residues in the transmembrane domains of both CRLF2 and IL-7Rα abrogated the TSLP-independent signal transduction and dimerization. The mutation of IL-7Rα W264 partially reduced the phosphorylation of STAT5 without affecting receptor dimerization. These results suggest that the amino acids in the transmembrane domains of EIM CRLF2 and IL-7Rα play at least three possible functions: interaction through hydrogen bonds, hydrophobic interaction, and signal transduction. Our findings contribute to a better understanding of the function of the transmembrane domains of cytokine receptors in their dimerization and signal transduction.
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Affiliation(s)
- Rio Yamamoto
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Miyagi, Japan
| | - Ryosuke Segawa
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Miyagi, Japan
| | - Hiyori Kato
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Miyagi, Japan
| | - Yuya Niino
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Miyagi, Japan
| | - Takeshi Sato
- Division of Liberal Arts and Science, Kyoto Pharmaceutical University, 607-8414 Kyoto, Japan
| | - Masahiro Hiratsuka
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Miyagi, Japan
| | - Noriyasu Hirasawa
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Miyagi, Japan.
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2
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Elucidation of the molecular interactions that enable stable assembly and structural diversity in multicomponent immune receptors. Proc Natl Acad Sci U S A 2021; 118:2026318118. [PMID: 34155106 DOI: 10.1073/pnas.2026318118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Multicomponent immune receptors are essential complexes in which distinct ligand-recognition and signaling subunits are held together by interactions between acidic and basic residues of their transmembrane helices. A 2:1 acidic-to-basic motif in the transmembrane domains of the subunits is necessary and sufficient to assemble these receptor complexes. Here, we study a prototype for these receptors, a DAP12-NKG2C 2:1 heterotrimeric complex, in which the two DAP12 subunits each contribute a single transmembrane Asp residue, and the NKG2C subunit contributes a Lys to form the complex. DAP12 can also associate with 20 other subunits using a similar motif. Here, we use molecular-dynamics simulations to understand the basis for the high affinity and diversity of interactions in this group of receptors. Simulations of the transmembrane helices with differing protonation states of the Asp-Asp-Lys triad identified a structurally stable interaction in which a singly-protonated Asp-Asp pair forms a hydrogen-bonded carboxyl-carboxylate clamp that clasps onto a charged Lys side chain. This polar motif was also supported by density functional theory and a Protein Data Bank-wide search. In contrast, the helices are dynamic at sites distal to the stable carboxyl-carboxylate clamp motif. Such a locally stable but globally dynamic structure is well suited to accommodate the sequence and structural variations in the transmembrane helices of multicomponent receptors, which mix and match subunits to create combinatorial functional diversity from a limited number of subunits. It also supports a signaling mechanism based on multisubunit clustering rather than propagation of rigid conformational changes through the membrane.
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3
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Makhlynets OV, Caputo GA. Characteristics and therapeutic applications of antimicrobial peptides. BIOPHYSICS REVIEWS 2021; 2:011301. [PMID: 38505398 PMCID: PMC10903410 DOI: 10.1063/5.0035731] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 12/31/2020] [Indexed: 12/20/2022]
Abstract
The demand for novel antimicrobial compounds is rapidly growing due to the phenomenon of antibiotic resistance in bacteria. In response, numerous alternative approaches are being taken including use of polymers, metals, combinatorial approaches, and antimicrobial peptides (AMPs). AMPs are a naturally occurring part of the immune system of all higher organisms and display remarkable broad-spectrum activity and high selectivity for bacterial cells over host cells. However, despite good activity and safety profiles, AMPs have struggled to find success in the clinic. In this review, we outline the fundamental properties of AMPs that make them effective antimicrobials and extend this into three main approaches being used to help AMPs become viable clinical options. These three approaches are the incorporation of non-natural amino acids into the AMP sequence to impart better pharmacological properties, the incorporation of AMPs in hydrogels, and the chemical modification of surfaces with AMPs for device applications. These approaches are being developed to enhance the biocompatibility, stability, and/or bioavailability of AMPs as clinical options.
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Affiliation(s)
- Olga V. Makhlynets
- Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244, USA
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4
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Hitchner MA, Santiago-Ortiz LE, Necelis MR, Shirley DJ, Palmer TJ, Tarnawsky KE, Vaden TD, Caputo GA. Activity and characterization of a pH-sensitive antimicrobial peptide. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:182984. [PMID: 31075228 DOI: 10.1016/j.bbamem.2019.05.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 12/20/2018] [Accepted: 01/06/2019] [Indexed: 12/11/2022]
Abstract
Antimicrobial peptides (AMPs) have been an area of great interest, due to the high selectivity of these molecules toward bacterial targets over host cells and the limited development of bacterial resistance to these molecules throughout evolution. Previous work showed that when Histidine was incorporated into the peptide C18G it lost antimicrobial activity. The role of pH on activity and biophysical properties of the peptide was investigated to explain this phenomenon. Minimal inhibitory concentration (MIC) results demonstrated that decreased media pH increased antimicrobial activity. Trichloroethanol (TCE) quenching and red-edge excitation spectroscopy (REES) showed a clear pH dependence on peptide aggregation in solution. Trp fluorescence was used to monitor binding to lipid vesicles and demonstrated the peptide binds to anionic bilayers at all pH values tested, however, binding to zwitterionic bilayers was enhanced at pH 7 and 8 (above the His pKa). Dual Quencher Analysis (DQA) confirmed the peptide inserted more deeply in PC:PG and PE:PG membranes, but could insert into PC bilayers at pH conditions above the His pKa. Bacterial membrane permeabilization assays which showed enhanced membrane permeabilization at pH 5 and 6 but vesicle leakage assays indicate enhanced permeabilization of PC and PC:PG bilayers at neutral pH. The results indicate the ionization of the His side chain affects the aggregation state of the peptide in solution and the conformation the peptide adopts when bound to bilayers, but there are likely more subtle influences of lipid composition and properties that impact the ability of the peptide to form pores in membranes.
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Affiliation(s)
- Morgan A Hitchner
- Department of Chemistry and Biochemistry, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028, United States of America
| | - Luis E Santiago-Ortiz
- Department of Chemistry and Biochemistry, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028, United States of America
| | - Matthew R Necelis
- Department of Chemistry and Biochemistry, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028, United States of America
| | - David J Shirley
- Department of Chemistry and Biochemistry, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028, United States of America
| | - Thaddeus J Palmer
- Department of Chemistry and Biochemistry, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028, United States of America
| | - Katharine E Tarnawsky
- Department of Chemistry and Biochemistry, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028, United States of America
| | - Timothy D Vaden
- Department of Chemistry and Biochemistry, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028, United States of America
| | - Gregory A Caputo
- Department of Chemistry and Biochemistry, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028, United States of America; Department of Molecular and Cellular Biosciences, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028, United States of America.
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5
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Caputo GA, London E. Analyzing Transmembrane Protein and Hydrophobic Helix Topography by Dual Fluorescence Quenching. Methods Mol Biol 2019; 2003:351-368. [PMID: 31218625 DOI: 10.1007/978-1-4939-9512-7_15] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The location of fluorescent groups relative to the lipid bilayer can be evaluated using fluorescence quenchers embedded in the membrane and/or dissolved in aqueous solution. Quenching can be used to define the membrane topography of membrane proteins and individual membrane-embedded hydrophobic helices by combining it with the placement of fluorescent groups, including Trp, at defined sequence positions. This chapter briefly discusses various quenching methods for studies of membrane protein topography, and provides detailed protocols for dual quencher analysis (DQA), a rapid, highly sensitive, and experimentally flexible approach in which the information gained from both a membrane-embedded and aqueous quencher is combined. The advantages of the DQA method include flexibility with regard to the bilayer compositions to which it can be applied, including membranes composed of lipids of varying head group and acyl chain compositions, as well as the ability to identify mixed populations of fluorophores residing at different depths within the bilayer.
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Affiliation(s)
- Gregory A Caputo
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ, USA
| | - Erwin London
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, USA.
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6
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Sandoval A, Eichler S, Madathil S, Reeves PJ, Fahmy K, Böckmann RA. The Molecular Switching Mechanism at the Conserved D(E)RY Motif in Class-A GPCRs. Biophys J 2017; 111:79-89. [PMID: 27410736 DOI: 10.1016/j.bpj.2016.06.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 05/31/2016] [Accepted: 06/08/2016] [Indexed: 10/21/2022] Open
Abstract
The disruption of ionic and H-bond interactions between the cytosolic ends of transmembrane helices TM3 and TM6 of class-A (rhodopsin-like) G protein-coupled receptors (GPCRs) is a hallmark for their activation by chemical or physical stimuli. In the bovine photoreceptor rhodopsin, this is accompanied by proton uptake at Glu(134) in the class-conserved D(E)RY motif. Studies on TM3 model peptides proposed a crucial role of the lipid bilayer in linking protonation to stabilization of an active state-like conformation. However, the molecular details of this linkage could not be resolved and have been addressed in this study by molecular dynamics (MD) simulations on TM3 model peptides in a bilayer of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). We show that protonation of the conserved glutamic acid alters the peptide insertion depth in the membrane, its side-chain rotamer preferences, and stabilizes the C-terminal helical structure. These factors contribute to the rise of the side-chain pKa (> 6) and to reduced polarity around the TM3 C terminus as confirmed by fluorescence spectroscopy. Helix stabilization requires the protonated carboxyl group; unexpectedly, this stabilization could not be evoked with an amide in MD simulations. Additionally, time-resolved Fourier transform infrared (FTIR) spectroscopy of TM3 model peptides revealed a different kinetics for lipid ester carbonyl hydration, suggesting that the carboxyl is linked to more extended H-bond clusters than an amide. Remarkably, this was seen as well in DOPC-reconstituted Glu(134)- and Gln(134)-containing bovine opsin mutants and demonstrates that the D(E)RY motif is a hydrated microdomain. The function of the D(E)RY motif as a proton switch is suggested to be based on the reorganization of the H-bond network at the membrane interface.
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Affiliation(s)
- Angelica Sandoval
- Computational Biology, Department of Biology, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Stefanie Eichler
- Helmholtz-Zentrum Dresden - Rossendorf, Institute of Resource Ecology, and Technische Universität Dresden, Dresden, Germany
| | - Sineej Madathil
- Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Philip J Reeves
- School of Biological Sciences, University of Essex, Colchester, United Kingdom
| | - Karim Fahmy
- Helmholtz-Zentrum Dresden - Rossendorf, Institute of Resource Ecology, and Technische Universität Dresden, Dresden, Germany.
| | - Rainer A Böckmann
- Computational Biology, Department of Biology, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
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7
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LeBarron J, London E. Highly Hydrophilic Segments Attached to Hydrophobic Peptides Translocate Rapidly across Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10752-10760. [PMID: 27649909 DOI: 10.1021/acs.langmuir.6b02597] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Hydrophilic segments attached to transmembrane helices often cross membranes. In an increasing number of cases, it has become apparent that this occurs in a biologically relevant post-translational event. In this study, we investigate whether juxta-membrane (JM) hydrophilic sequences attached to hydrophobic helices are able to rapidly cross lipid bilayers via their ability or inability to block hydrophobic helix interconversion between a transmembrane (TM) and non-TM membrane-associated state. Interconversion was triggered by changing the protonation state of an Asp residue in the hydrophobic core of the peptides, and peptide configuration was monitored by the fluorescence of a Trp residue at the center of the hydrophobic sequence. In POPC vesicles, conversion of the TM to non-TM state at high pH and the non-TM to TM state at low pH was rapid (seconds or less) for KK, KKNN, and the KKNNNNNN flanking sequences on both N- and C-termini and the KLFAGHQ sequence that flanks the spontaneously TM-inserting 3A protein of polio virus. In vesicles composed of 6:4 (mol/mol) POPC/cholesterol, interconversion was still rapid, with the exception of the peptide flanked by KKNNNNNN sequences, for which the half time of interconversion slowed to minutes. This behavior suggests that, at least in membranes with low levels of cholesterol, movement of hydrophilic JM segments (and analogous hydrophobic loops in multipass TM proteins) across membranes may be more facile than previously thought. This may have important biological implications.
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Affiliation(s)
- Jamie LeBarron
- Stony Brook University Stony Brook, New York 11794-5215, United States
| | - Erwin London
- Stony Brook University Stony Brook, New York 11794-5215, United States
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8
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Lewis AK, Valley CC, Peery SL, Brummel B, Braun AR, Karim CB, Sachs JN. Death Receptor 5 Networks Require Membrane Cholesterol for Proper Structure and Function. J Mol Biol 2016; 428:4843-4855. [PMID: 27720987 DOI: 10.1016/j.jmb.2016.10.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 09/16/2016] [Accepted: 10/02/2016] [Indexed: 12/13/2022]
Abstract
Death receptor 5 (DR5) is an apoptosis-inducing member of the tumor necrosis factor receptor superfamily, whose activity has been linked to membrane cholesterol content. Upon ligand binding, DR5 forms large clusters within the plasma membrane that have often been assumed to be manifestations of receptor co-localization in cholesterol-rich membrane domains. However, we have recently shown that DR5 clusters are more than just randomly aggregated receptors. Instead, these are highly structured networks held together by receptor dimers. These dimers are stabilized by specific transmembrane helix-helix interactions, including a disulfide bond in the long isoform of the receptor. The complex relationships among DR5 network formation, transmembrane helix dimerization, membrane cholesterol, and receptor activity has not been established. It is unknown whether the membrane itself plays an active role in driving DR5 transmembrane helix interactions or in the formation of the networks. We show that cholesterol depletion in cells does not inhibit the formation of DR5 networks. However, the networks that form in cholesterol-depleted cells fail to induce caspase cleavage. These results suggest a potential structural difference between active and inactive networks. As evidence, we show that cholesterol is necessary for the covalent dimerization of DR5 transmembrane domains. Molecular simulations and experiments in synthetic vesicles on the DR5 transmembrane dimer suggest that dimerization is facilitated by increased helicity in a thicker bilayer.
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Affiliation(s)
- Andrew K Lewis
- Department of Biomedical Engineering, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Christopher C Valley
- Department of Biomedical Engineering, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Stephen L Peery
- Department of Biomedical Engineering, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Benjamin Brummel
- Department of Biomedical Engineering, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Anthony R Braun
- Department of Biomedical Engineering, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Christine B Karim
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Jonathan N Sachs
- Department of Biomedical Engineering, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA.
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9
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LeBarron J, London E. Effect of lipid composition and amino acid sequence upon transmembrane peptide-accelerated lipid transleaflet diffusion (flip-flop). BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1812-20. [PMID: 27131444 DOI: 10.1016/j.bbamem.2016.04.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 03/21/2016] [Accepted: 04/21/2016] [Indexed: 12/15/2022]
Abstract
We examined how hydrophobic peptide-accelerated transleaflet lipid movement (flip-flop) was affected by peptide sequence and vesicle composition and properties. A peptide with a completely hydrophobic sequence had little if any effect upon flip-flop. While peptides with a somewhat less hydrophobic sequence accelerated flip-flop, the half-time remained slow (hours) with substantial (0.5mol%) peptide in the membranes. It appears that peptide-accelerated lipid flip-flop involves a rare event that may reflect a rare state of the peptide or lipid bilayer. There was no simple relationship between peptide overall hydrophobicity and flip-flop. In addition, flip-flop was not closely linked to whether the peptides were in a transmembrane or non-transmembrane (interfacial) inserted state. Flip-flop was also not associated with peptide-induced pore formation. We found that peptide-accelerated flip-flop is initially faster in small (highly curved) unilamellar vesicles relative to that in large unilamellar vesicles. Peptide-accelerated flip-flop was also affected by lipid composition, being slowed in vesicles with thick bilayers or those containing 30% cholesterol. Interestingly, these factors also slow spontaneous lipid flip-flop in the absence of peptide. Combined with previous studies, the results are most consistent with acceleration of lipid flip-flop by peptide-induced thinning of bilayer width.
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Affiliation(s)
- Jamie LeBarron
- Dept. of Biochemistry and Cell Biology, Stony Brook, NY 11794-5215, United States
| | - Erwin London
- Dept. of Biochemistry and Cell Biology, Stony Brook, NY 11794-5215, United States
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10
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Lin Q, London E. The influence of natural lipid asymmetry upon the conformation of a membrane-inserted protein (perfringolysin O). J Biol Chem 2014; 289:5467-78. [PMID: 24398685 DOI: 10.1074/jbc.m113.533943] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Eukaryotic membrane proteins generally reside in membrane bilayers that have lipid asymmetry. However, in vitro studies of the impact of lipids upon membrane proteins are generally carried out in model membrane vesicles that lack lipid asymmetry. Our recently developed method to prepare lipid vesicles with asymmetry similar to that in plasma membranes and with controlled amounts of cholesterol was used to investigate the influence of lipid composition and lipid asymmetry upon the conformational behavior of the pore-forming, cholesterol-dependent cytolysin perfringolysin O (PFO). PFO conformational behavior in asymmetric vesicles was found to be distinct both from that in symmetric vesicles with the same lipid composition as the asymmetric vesicles and from that in vesicles containing either only the inner leaflet lipids from the asymmetric vesicles or only the outer leaflet lipids from the asymmetric vesicles. The presence of phosphatidylcholine in the outer leaflet increased the cholesterol concentration required to induce PFO binding, whereas phosphatidylethanolamine and phosphatidylserine in the inner leaflet of asymmetric vesicles stabilized the formation of a novel deeply inserted conformation that does not form pores, even though it contains transmembrane segments. This conformation may represent an important intermediate stage in PFO pore formation. These studies show that lipid asymmetry can strongly influence the behavior of membrane-inserted proteins.
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Affiliation(s)
- Qingqing Lin
- From the Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York 11794-5215
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11
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Analyzing transmembrane protein and hydrophobic helix topography by dual fluorescence quenching. Methods Mol Biol 2013; 974:279-95. [PMID: 23404281 DOI: 10.1007/978-1-62703-275-9_13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The location of fluorescent groups relative to the lipid bilayer can be evaluated using fluorescence quenchers embedded in the membrane and/or dissolved in aqueous solution. Quenching can be used to define the membrane topography of membrane proteins and individual membrane-embedded hydrophobic helices by combining it with the placement of fluorescent groups, including Trp, at defined sequence positions. This chapter briefly discusses various quenching methods for studies of membrane protein topography and provides detailed protocols for dual quencher analysis, a rapid, highly sensitive, and experimentally flexible approach in which the information gained from both a membrane-embedded and aqueous quencher is combined.
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12
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Caputo GA. Analyzing the effects of hydrophobic mismatch on transmembrane α-helices using tryptophan fluorescence spectroscopy. Methods Mol Biol 2013; 1063:95-116. [PMID: 23975773 DOI: 10.1007/978-1-62703-583-5_5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hydrophobic matching between transmembrane protein segments and the lipid bilayer in which they are embedded is a significant factor in the behavior and orientation of such transmembrane segments. The condition of hydrophobic mismatch occurs when the hydrophobic thickness of a lipid bilayer is significantly different than the length of the membrane spanning segment of a protein, resulting in a mismatch. This mismatch can result in altered function of proteins as well as nonnative structural arrangements including effects on transmembrane α-helix tilt angles, oligomerization state, and/or the formation of non-transmembrane topographies. Here, a fluorescence-based protocol is described for testing model transmembrane α-helices and their sensitivity to hydrophobic mismatch by measuring the propensity of these helices to form non-transmembrane structures. Overall, good hydrophobic matching between the bilayer and transmembrane segments is an important factor that must be considered when designing membrane proteins or peptides.
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Affiliation(s)
- Gregory A Caputo
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ, USA
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13
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Prasanna X, Praveen PJ, Sengupta D. Sequence dependent lipid-mediated effects modulate the dimerization of ErbB2 and its associative mutants. Phys Chem Chem Phys 2013; 15:19031-41. [DOI: 10.1039/c3cp52447g] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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14
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Polyansky AA, Volynsky PE, Efremov RG. Multistate Organization of Transmembrane Helical Protein Dimers Governed by the Host Membrane. J Am Chem Soc 2012; 134:14390-400. [DOI: 10.1021/ja303483k] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Anton A. Polyansky
- Department of Structural and
Computational Biology, Max F. Perutz Laboratories, University of Vienna, Campus Vienna Biocenter 5, Vienna, AT-1030,
Austria
- M.M. Shemyakin
and Yu.A. Ovchinnikov
Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - Pavel E. Volynsky
- M.M. Shemyakin
and Yu.A. Ovchinnikov
Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - Roman G. Efremov
- M.M. Shemyakin
and Yu.A. Ovchinnikov
Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
- Moscow Institute of Physics and Technology (State University), Dolgoprudny,
Moscow Region, 141700, Russia
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15
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Beevers AJ, Nash A, Salazar-Cancino M, Scott DJ, Notman R, Dixon AM. Effects of the Oncogenic V664E Mutation on Membrane Insertion, Structure, and Sequence-Dependent Interactions of the Neu Transmembrane Domain in Micelles and Model Membranes: An Integrated Biophysical and Simulation Study. Biochemistry 2012; 51:2558-68. [DOI: 10.1021/bi201269w] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | - David J. Scott
- Department of Biosciences, University of Nottingham, Nottingham, U.K
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16
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Li E, Wimley WC, Hristova K. Transmembrane helix dimerization: beyond the search for sequence motifs. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:183-93. [PMID: 21910966 DOI: 10.1016/j.bbamem.2011.08.031] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 08/25/2011] [Accepted: 08/26/2011] [Indexed: 01/07/2023]
Abstract
Studies of the dimerization of transmembrane (TM) helices have been ongoing for many years now, and have provided clues to the fundamental principles behind membrane protein (MP) folding. Our understanding of TM helix dimerization has been dominated by the idea that sequence motifs, simple recognizable amino acid sequences that drive lateral interaction, can be used to explain and predict the lateral interactions between TM helices in membrane proteins. But as more and more unique interacting helices are characterized, it is becoming clear that the sequence motif paradigm is incomplete. Experimental evidence suggests that the search for sequence motifs, as mediators of TM helix dimerization, cannot solve the membrane protein folding problem alone. Here we review the current understanding in the field, as it has evolved from the paradigm of sequence motifs into a view in which the interactions between TM helices are much more complex. This article is part of a Special Issue entitled: Membrane protein structure and function.
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Affiliation(s)
- Edwin Li
- Department of Biology, Saint Joseph's University, Philadelphia, PA 19131, USA
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Beevers AJ, Damianoglou A, Oates J, Rodger A, Dixon AM. Sequence-Dependent Oligomerization of the Neu Transmembrane Domain Suggests Inhibition of “Conformational Switching” by an Oncogenic Mutant. Biochemistry 2010; 49:2811-20. [DOI: 10.1021/bi902087v] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Andrew J. Beevers
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | | | - Joanne Oates
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Alison Rodger
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Ann M. Dixon
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
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