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Westerfield JM, Barrera FN. Membrane receptor activation mechanisms and transmembrane peptide tools to elucidate them. J Biol Chem 2019; 295:1792-1814. [PMID: 31879273 DOI: 10.1074/jbc.rev119.009457] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Single-pass membrane receptors contain extracellular domains that respond to external stimuli and transmit information to intracellular domains through a single transmembrane (TM) α-helix. Because membrane receptors have various roles in homeostasis, signaling malfunctions of these receptors can cause disease. Despite their importance, there is still much to be understood mechanistically about how single-pass receptors are activated. In general, single-pass receptors respond to extracellular stimuli via alterations in their oligomeric state. The details of this process are still the focus of intense study, and several lines of evidence indicate that the TM domain (TMD) of the receptor plays a central role. We discuss three major mechanistic hypotheses for receptor activation: ligand-induced dimerization, ligand-induced rotation, and receptor clustering. Recent observations suggest that receptors can use a combination of these activation mechanisms and that technical limitations can bias interpretation. Short peptides derived from receptor TMDs, which can be identified by screening or rationally developed on the basis of the structure or sequence of their targets, have provided critical insights into receptor function. Here, we explore recent evidence that, depending on the target receptor, TMD peptides cannot only inhibit but also activate target receptors and can accommodate novel, bifunctional designs. Furthermore, we call for more sharing of negative results to inform the TMD peptide field, which is rapidly transforming into a suite of unique tools with the potential for future therapeutics.
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Affiliation(s)
- Justin M Westerfield
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996
| | - Francisco N Barrera
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996.
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2
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Nguyen VP, Alves DS, Scott HL, Davis FL, Barrera FN. A Novel Soluble Peptide with pH-Responsive Membrane Insertion. Biochemistry 2015; 54:6567-75. [DOI: 10.1021/acs.biochem.5b00856] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Vanessa P. Nguyen
- Department of Biochemistry
and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Daiane S. Alves
- Department of Biochemistry
and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Haden L. Scott
- Department of Biochemistry
and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Forrest L. Davis
- Department of Biochemistry
and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Francisco N. Barrera
- Department of Biochemistry
and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996, United States
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3
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Andreu-Fernández V, Genoves A, Lee TH, Stellato M, Lucantoni F, Orzáez M, Mingarro I, Aguilar MI, Pérez-Payá E. Peptides derived from the transmembrane domain of Bcl-2 proteins as potential mitochondrial priming tools. ACS Chem Biol 2014; 9:1799-811. [PMID: 24905660 DOI: 10.1021/cb5002679] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The Bcl-2 family of proteins is crucial for apoptosis regulation. Members of this family insert through a specific C-terminal anchoring transmembrane domain (TMD) in the mitochondrial outer membrane where they hierarchically interact to determine cell fate. While the mitochondrial membrane has been proposed to actively participate in these protein-protein interactions, the influence of the TMD in the membrane-mediated interaction is poorly understood. Synthetic peptides (TMD-pepts) corresponding to the putative TMD of antiapoptotic (Bcl-2, Bcl-xL, Bcl-w, and Mcl-1) and pro-apoptotic (Bax, Bak) members were synthesized and characterized. TMD-pepts bound more efficiently to mitochondria-like bilayers than to plasma membrane-like bilayers, and higher binding correlated with greater membrane perturbation. The Bcl-2 TMD peptides promoted mitochondrial outer membrane permeabilization (MOMP) and cytochrome c release from isolated mitochondria and different cell lines. TMD-pepts exhibited nonapoptotic pro-death activity when apoptosis stimuli were absent. In addition, the peptides enhanced the apoptotic pathway induced by chemotherapeutic agents in cotreatment. Overall, the membrane perturbation effects of the TMD-pepts observed in the present study open the way for their use as new chemical tools to sensitize tumor cells to chemotherapeutic agents, in accordance with the concept of mitochondria priming.
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Affiliation(s)
- Vicente Andreu-Fernández
- Laboratory
of Peptide and Protein Chemistry, Centro de Investigación Príncipe Felipe, E-46012 Valencia, Spain
| | - Ainhoa Genoves
- Laboratory
of Peptide and Protein Chemistry, Centro de Investigación Príncipe Felipe, E-46012 Valencia, Spain
- Instituto de Biomedicina de Valencia, IBV-CSIC, E-46010 Valencia, Spain
| | - Tzong-Hsien Lee
- Department
of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800 Australia
| | - Matthew Stellato
- Department
of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800 Australia
| | - Federico Lucantoni
- Laboratory
of Peptide and Protein Chemistry, Centro de Investigación Príncipe Felipe, E-46012 Valencia, Spain
| | - Mar Orzáez
- Laboratory
of Peptide and Protein Chemistry, Centro de Investigación Príncipe Felipe, E-46012 Valencia, Spain
| | - Ismael Mingarro
- Departament
de Bioquímica i Biologia Molecular, Universitat de València, 46100 Burjassot, Spain
| | - Marie-Isabel Aguilar
- Department
of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800 Australia
| | - Enrique Pérez-Payá
- Laboratory
of Peptide and Protein Chemistry, Centro de Investigación Príncipe Felipe, E-46012 Valencia, Spain
- Instituto de Biomedicina de Valencia, IBV-CSIC, E-46010 Valencia, Spain
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4
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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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Godfroy JI, Roostan M, Moroz YS, Korendovych IV, Yin H. Isolated Toll-like receptor transmembrane domains are capable of oligomerization. PLoS One 2012; 7:e48875. [PMID: 23155421 PMCID: PMC3498381 DOI: 10.1371/journal.pone.0048875] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Accepted: 10/01/2012] [Indexed: 12/13/2022] Open
Abstract
Toll-like receptors (TLRs) act as the first line of defense against bacterial and viral pathogens by initiating critical defense signals upon dimer activation. The contribution of the transmembrane domain in the dimerization and signaling process has heretofore been overlooked in favor of the extracellular and intracellular domains. As mounting evidence suggests that the transmembrane domain is a critical region in several protein families, we hypothesized that this was also the case for Toll-like receptors. Using a combined biochemical and biophysical approach, we investigated the ability of isolated Toll-like receptor transmembrane domains to interact independently of extracellular domain dimerization. Our results showed that the transmembrane domains had a preference for the native dimer partners in bacterial membranes for the entire receptor family. All TLR transmembrane domains showed strong homotypic interaction potential. The TLR2 transmembrane domain demonstrated strong heterotypic interactions in bacterial membranes with its known interaction partners, TLR1 and TLR6, as well as with a proposed interaction partner, TLR10, but not with TLR4, TLR5, or unrelated transmembrane receptors providing evidence for the specificity of TLR2 transmembrane domain interactions. Peptides for the transmembrane domains of TLR1, TLR2, and TLR6 were synthesized to further study this subfamily of receptors. These peptides validated the heterotypic interactions seen in bacterial membranes and demonstrated that the TLR2 transmembrane domain had moderately strong interactions with both TLR1 and TLR6. Combined, these results suggest a role for the transmembrane domain in Toll-like receptor oligomerization and as such, may be a novel target for further investigation of new therapeutic treatments of Toll-like receptor mediated diseases.
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Affiliation(s)
- James I. Godfroy
- Department of Chemical and Biological Engineering, University of Colorado at Boulder, Boulder, Colorado, United States of America
| | - Mohammad Roostan
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado, United States of America
| | - Yurii S. Moroz
- Department of Chemistry, Syracuse University, Syracuse, New York, United States of America
| | - Ivan V. Korendovych
- Department of Chemistry, Syracuse University, Syracuse, New York, United States of America
| | - Hang Yin
- Department of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado at Boulder, Boulder, Colorado, United States of America
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Abstract
Membrane-spanning α-helices represent major sites of protein-protein interaction in membrane protein oligomerization and folding. As such, these interactions may be of exquisite specificity. Specificity often rests on a complex interplay of different types of residues forming the helix-helix interfaces via dense packing and different non-covalent forces, including van der Waal’s forces, hydrogen bonding, charge-charge interactions, and aromatic interactions. These interfaces often contain complex residue motifs where the contribution of constituent amino acids depends on the context of the surrounding sequence. Moreover, transmembrane helix-helix interactions are increasingly recognized as being dynamic and dependent on the functional state of a given protein.
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Langosch D, Arkin IT. Interaction and conformational dynamics of membrane-spanning protein helices. Protein Sci 2009; 18:1343-58. [PMID: 19530249 PMCID: PMC2775205 DOI: 10.1002/pro.154] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 04/19/2009] [Accepted: 04/20/2009] [Indexed: 12/23/2022]
Abstract
Within 1 or 2 decades, the reputation of membrane-spanning alpha-helices has changed dramatically. Once mostly regarded as dull membrane anchors, transmembrane domains are now recognized as major instigators of protein-protein interaction. These interactions may be of exquisite specificity in mediating assembly of stable membrane protein complexes from cognate subunits. Further, they can be reversible and regulatable by external factors to allow for dynamic changes of protein conformation in biological function. Finally, these helices are increasingly regarded as dynamic domains. These domains can move relative to each other in different functional protein conformations. In addition, small-scale backbone fluctuations may affect their function and their impact on surrounding lipid shells. Elucidating the ways by which these intricate structural features are encoded by the amino acid sequences will be a fascinating subject of research for years to come.
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Affiliation(s)
- Dieter Langosch
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany.
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Tang J, Yin H, Qiu J, Tucker MJ, DeGrado WF, Gai F. Using two fluorescent probes to dissect the binding, insertion, and dimerization kinetics of a model membrane peptide. J Am Chem Soc 2009; 131:3816-7. [PMID: 19256494 DOI: 10.1021/ja809007f] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Helix-helix association within a membrane environment represents one of the fundamental processes in membrane protein folding. However, studying the kinetics of such processes has been difficult because most membrane proteins are insoluble in aqueous solution. Here we present a stopped-flow fluorescence study of the membrane-interaction kinetics of a designed, water-soluble transmembrane (TM) peptide, anti-alpha(IIb), which is known to dimerize in phospholipid bilayers. We show that by using two fluorescent amino acids, tryptophan and p-cyanophenylalanine, we are able to kinetically dissect distinct phases in the peptide-membrane interaction, representing membrane binding, membrane insertion, and TM helix-helix association. Our results further show that the last process occurs on a time scale of seconds, indicating that the association of two TM helices is an intrinsically slow event.
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Affiliation(s)
- Jia Tang
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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