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Amos C, Kiessling V, Kreutzberger AJB, Schenk NA, Mohan R, Nyenhuis S, Doyle CA, Wang HY, Levental K, Levental I, Anantharam A, Tamm LK. Membrane lipids couple synaptotagmin to SNARE-mediated granule fusion in insulin-secreting cells. Mol Biol Cell 2024; 35:ar12. [PMID: 38117594 PMCID: PMC10916878 DOI: 10.1091/mbc.e23-06-0225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 12/04/2023] [Accepted: 12/14/2023] [Indexed: 12/22/2023] Open
Abstract
Insulin secretion depends on the Ca2+-regulated fusion of granules with the plasma membrane. A recent model of Ca2+-triggered exocytosis in secretory cells proposes that lipids in the plasma membrane couple the calcium sensor Syt1 to the membrane fusion machinery (Kiessling et al., 2018). Specifically, Ca2+-mediated binding of Syt1's C2 domains to the cell membrane shifts the membrane-anchored SNARE syntaxin-1a to a more fusogenic conformation, straightening its juxtamembrane linker. To test this model in live cells and extend it to insulin secretion, we enriched INS1 cells with a panel of lipids with different acyl chain compositions. Fluorescence lifetime measurements demonstrate that cells with more disordered membranes show an increase in fusion efficiency, and vice versa. Experiments with granules purified from INS1 cells and recombinant SNARE proteins reconstituted in supported membranes confirmed that lipid acyl chain composition determines SNARE conformation and that lipid disordering correlates with increased fusion. Addition of Syt1's C2AB domains significantly decreased lipid order in target membranes and increased SNARE-mediated fusion probability. Strikingly, Syt's action on both fusion and lipid order could be partially bypassed by artificially increasing unsaturated phosphatidylserines in the target membrane. Thus, plasma membrane lipids actively participate in coupling Ca2+/synaptotagmin-sensing to the SNARE fusion machinery in cells.
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Affiliation(s)
- Chase Amos
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Alex J. B. Kreutzberger
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Noah A. Schenk
- Department of Neurosciences, University of Toledo, Toledo, OH 43614
| | - Ramkumar Mohan
- Department of Neurosciences, University of Toledo, Toledo, OH 43614
| | - Sarah Nyenhuis
- Department of Chemistry, University of Virginia, Charlottesville, VA, 22904
| | - Catherine A. Doyle
- Department of Pharmacology, University of Virginia Health System, Charlottesville, VA 22908
| | - Hong-Yin Wang
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Kandice Levental
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Ilya Levental
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Arun Anantharam
- Department of Neurosciences, University of Toledo, Toledo, OH 43614
| | - Lukas K. Tamm
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
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Odongo L, Habtegebrael BH, Kiessling V, White JM, Tamm LK. A novel in vitro system of supported planar endosomal membranes (SPEMs) reveals an enhancing role for cathepsin B in the final stage of Ebola virus fusion and entry. Microbiol Spectr 2023; 11:e0190823. [PMID: 37728342 PMCID: PMC10581071 DOI: 10.1128/spectrum.01908-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 07/17/2023] [Indexed: 09/21/2023] Open
Abstract
Ebola virus (EBOV) causes a hemorrhagic fever with fatality rates up to 90%. The EBOV entry process is complex and incompletely understood. Following attachment to host cells, EBOV is trafficked to late endosomes/lysosomes where its glycoprotein (GP) is processed to a 19-kDa form, which binds to the EBOV intracellular receptor Niemann-Pick type C1. We previously showed that the cathepsin protease inhibitor, E-64d, blocks infection by pseudovirus particles bearing 19-kDa GP, suggesting that further cathepsin action is needed to trigger fusion. This, however, has not been demonstrated directly. Since 19-kDa Ebola GP fusion occurs in late endosomes, we devised a system in which enriched late endosomes are used to prepare supported planar endosomal membranes (SPEMs), and fusion of fluorescent (pseudo)virus particles is monitored by total internal reflection fluorescence microscopy. We validated the system by demonstrating the pH dependencies of influenza virus hemagglutinin (HA)-mediated and Lassa virus (LASV) GP-mediated fusion. Using SPEMs, we showed that fusion mediated by 19-kDa Ebola GP is dependent on low pH, enhanced by Ca2+, and augmented by the addition of cathepsins. Subsequently, we found that E-64d inhibits full fusion, but not lipid mixing, mediated by 19-kDa GP, which we corroborated with the reversible cathepsin inhibitor VBY-825. Hence, we provide both gain- and loss-of-function evidence that further cathepsin action enhances the fusion activity of 19-kDa Ebola GP. In addition to providing new insights into how Ebola GP mediates fusion, the approach we developed employing SPEMs can now be broadly used for studies of virus and toxin entry through endosomes. IMPORTANCE Ebola virus is the causative agent of Ebola virus disease, which is severe and frequently lethal. EBOV gains entry into cells via late endosomes/lysosomes. The events immediately preceding fusion of the viral and endosomal membranes are incompletely understood. In this study, we report a novel in vitro system for studying virus fusion with endosomal membranes. We validated the system by demonstrating the low pH dependencies of influenza and Lassa virus fusion. Moreover, we show that further cathepsin B action enhances the fusion activity of the primed Ebola virus glycoprotein. Finally, this model endosomal membrane system should be useful in studying the mechanisms of bilayer breaching by other enveloped viruses, by non-enveloped viruses, and by acid-activated bacterial toxins.
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Affiliation(s)
- Laura Odongo
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA
| | - Betelihem H. Habtegebrael
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA
| | - Volker Kiessling
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA
| | - Judith M. White
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia, USA
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Lukas K. Tamm
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA
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Ward AE, Sokovikova D, Waxham MN, Heberle FA, Levental I, Levental KR, Kiessling V, White JM, Tamm LK. Serinc5 Restricts HIV Membrane Fusion by Altering Lipid Order and Heterogeneity in the Viral Membrane. ACS Infect Dis 2023; 9:773-784. [PMID: 36946615 PMCID: PMC10366416 DOI: 10.1021/acsinfecdis.2c00478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
The host restriction factor, Serinc5, incorporates into budding HIV particles and inhibits their infection by an incompletely understood mechanism. We have previously reported that Serinc5 but not its paralogue, Serinc2, blocks HIV cell entry by membrane fusion, specifically by inhibiting fusion pore formation and dilation. A body of work suggests that Serinc5 may alter the conformation and clustering of the HIV fusion protein, Env. To contribute an additional perspective to the developing model of Serinc5 restriction, we assessed Serinc2 and Serinc5's effects on HIV pseudoviral membranes. By measuring pseudoviral membrane thickness via cryo-electron microscopy and order via the fluorescent dye, FLIPPER-TR, Serinc5 was found to increase membrane heterogeneity, skewing the distribution toward a larger fraction of the viral membrane in an ordered phase. We also directly observed for the first time the coexistence of membrane domains within individual viral membrane envelopes. Using a total internal reflection fluorescence-based single particle fusion assay, we found that treatment of HIV pseudoviral particles with phosphatidylethanolamine (PE) rescued HIV pseudovirus fusion from restriction by Serinc5, which was accompanied by decreased membrane heterogeneity and order. This effect was specific for PE and did not depend on acyl chain length or saturation. Together, these data suggest that Serinc5 alters multiple interrelated properties of the viral membrane─lipid chain order, rigidity, line tension, and lateral pressure─which decrease the accessibility of fusion intermediates and disfavor completion of fusion. These biophysical insights into Serinc5 restriction of HIV infectivity could contribute to the development of novel antivirals that exploit the same weaknesses.
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Affiliation(s)
- Amanda E. Ward
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Daria Sokovikova
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Melvin Neal Waxham
- Department of Neurobiology and Anatomy, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX 77030
| | | | - Ilya Levental
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Kandice R. Levental
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Judith M. White
- Department of Cell Biology, University of Virginia Health System, Charlottesville, VA 22908
| | - Lukas K. Tamm
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
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Coffman RE, Kraichely KN, Kreutzberger AJB, Kiessling V, Tamm LK, Woodbury DJ. In a model of exocytosis, alcohol enhances vesicle fusion by acting on membrane lipids, not SNARE proteins. Biophys J 2023; 122:513a-514a. [PMID: 36784653 DOI: 10.1016/j.bpj.2022.11.2732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
| | - Katelyn N Kraichely
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA, USA
| | - Alex J B Kreutzberger
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA, USA
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA, USA
| | - Lukas K Tamm
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA, USA
| | - Dixon J Woodbury
- Neuroscience Center, Brigham Young University, Provo, UT, USA; Cell Biology and Physiology, Brigham Young University, Provo, UT, USA
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5
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Odongo L, Kiessling V, White JM, Tamm LK. Demonstration, using novel supported planar endosomal membranes (SPEM), that further cathepsin action augments the fusion activity of the primed (19-kDa) Ebola virus glycoprotein. Biophys J 2023; 122:321a-322a. [PMID: 36783621 DOI: 10.1016/j.bpj.2022.11.1801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Laura Odongo
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Judith M White
- Department of Cell Biology, University of Virginia, Charlottesville, VA, USA
| | - Lukas K Tamm
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
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6
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Tomaka W, Kiessling V, Tamm LK. Munc18-lipid interplay and spatial arrangements of Syntaxin-1a. Biophys J 2023; 122:516a. [PMID: 36784671 DOI: 10.1016/j.bpj.2022.11.2743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Weronika Tomaka
- Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Volker Kiessling
- Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Lukas K Tamm
- Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
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Prasad N, Tomaka W, Castellani F, Yau O, Kraichely K, Rathore S, Kreutzberger AJB, Kiessling V, Lindau M. Combining fluorescence and electrochemical imaging of chromaffin granule fusion with supported bilayers. Biophys J 2023; 122:498a. [PMID: 36784567 DOI: 10.1016/j.bpj.2022.11.2659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
| | | | | | | | | | | | | | | | - Manfred Lindau
- Cornell University, Ithaca, NY, USA; Miller School of Medicine, University of Miami, Miami, FL, USA
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8
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Coffman RE, Kraichely KN, Kreutzberger AJB, Kiessling V, Tamm LK, Woodbury DJ. Drunken lipid membranes, not drunken SNARE proteins, promote fusion in a model of neurotransmitter release. Front Mol Neurosci 2022; 15:1022756. [PMID: 36311016 PMCID: PMC9614348 DOI: 10.3389/fnmol.2022.1022756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 09/20/2022] [Indexed: 11/29/2022] Open
Abstract
Alcohol affects many neuronal proteins that are upstream or down-stream of synaptic vesicle fusion and neurotransmitter release. Less well studied is alcohol’s effect on the fusion machinery including SNARE proteins and lipid membranes. Using a SNARE-driven fusion assay we show that fusion probability is significantly increased at 0.4% v/v (68 mM) ethanol; but not with methanol up to 10%. Ethanol appears to act directly on membrane lipids since experiments focused on protein properties [circular dichroism spectrometry, site-directed fluorescence interference contrast (sdFLIC) microscopy, and vesicle docking results] showed no significant changes up to 5% ethanol, but a protein-free fusion assay also showed increased lipid membrane fusion rates with 0.4% ethanol. These data show that the effects of high physiological doses of ethanol on SNARE-driven fusion are mediated through ethanol’s interaction with the lipid bilayer of membranes and not SNARE proteins, and that methanol affects lipid membranes and SNARE proteins only at high doses.
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Affiliation(s)
- Robert E. Coffman
- Neuroscience Center, Brigham Young University, Provo, UT, United States
| | - Katelyn N. Kraichely
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA, United States
| | - Alex J. B. Kreutzberger
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA, United States
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA, United States
| | - Lukas K. Tamm
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA, United States
| | - Dixon J. Woodbury
- Neuroscience Center, Brigham Young University, Provo, UT, United States
- Department of Cell Biology and Physiology, Brigham Young University, Provo, UT, United States
- *Correspondence: Dixon J. Woodbury,
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9
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Liang Q, Ofosuhene AP, Kiessling V, Liang B, Kreutzberger AJB, Tamm LK, Cafiso DS. Complexin-1 and synaptotagmin-1 compete for binding sites on membranes containing PtdInsP 2. Biophys J 2022; 121:3370-3380. [PMID: 36016497 PMCID: PMC9515229 DOI: 10.1016/j.bpj.2022.08.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 07/28/2022] [Accepted: 08/19/2022] [Indexed: 11/25/2022] Open
Abstract
Complexin-1 is an essential protein for neuronal exocytosis that acts to depress spontaneous fusion events while enhancing evoked neurotransmitter release. In addition to binding soluble N-ethylmaleimide-sensitive factor attachment protein receptors, it is well established that complexin associates with membranes in a manner that depends upon membrane curvature. In the present work, we examine the membrane binding of complexin using electron paramagnetic resonance spectroscopy, fluorescence anisotropy, and total internal reflection fluorescence microscopy. The apparent membrane affinity of complexin is found to strongly depend upon the concentration of protein used in the binding assay, and this is a result of a limited number of binding sites for complexin on the membrane interface. Although both the N- and C-terminal regions of complexin associate with the membrane interface, membrane affinity is driven by its C-terminus. Complexin prefers to bind liquid-disordered membrane phases and shows an enhanced affinity toward membranes containing phosphatidylinositol 4-5-bisphosphate (PI(4,5)P2). In the presence of PI(4,5)P2, complexin is displaced from the membrane surface by proteins that bind to or sequester PI(4,5)P2. In particular, the neuronal calcium sensor synaptotagmin-1 displaces complexin from the membrane but only when PI(4,5)P2 is present. Complexin and synaptotagmin compete on the membrane interface in the presence of PI(4,5)P2, and this interaction may play a role in calcium-triggered exocytosis by displacing complexin from its fusion-inhibiting state.
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Affiliation(s)
- Qian Liang
- Department of Chemistry, University of Virginia, Charlottesville, Virginia
| | - Akosua P Ofosuhene
- Department of Chemistry, University of Virginia, Charlottesville, Virginia
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics University of Virginia, Charlottesville, Virginia; Center for Membrane Biology, University of Virginia, Charlottesville, Virginia
| | - Binyong Liang
- Department of Molecular Physiology and Biological Physics University of Virginia, Charlottesville, Virginia; Center for Membrane Biology, University of Virginia, Charlottesville, Virginia
| | - Alex J B Kreutzberger
- Department of Molecular Physiology and Biological Physics University of Virginia, Charlottesville, Virginia; Center for Membrane Biology, University of Virginia, Charlottesville, Virginia
| | - Lukas K Tamm
- Department of Molecular Physiology and Biological Physics University of Virginia, Charlottesville, Virginia; Center for Membrane Biology, University of Virginia, Charlottesville, Virginia
| | - David S Cafiso
- Department of Chemistry, University of Virginia, Charlottesville, Virginia; Center for Membrane Biology, University of Virginia, Charlottesville, Virginia.
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10
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Cabot M, Kiessling V, White JM, Tamm LK. Endosomes supporting fusion mediated by vesicular stomatitis virus glycoprotein have distinctive motion and acidification. Traffic 2022; 23:221-234. [PMID: 35147273 PMCID: PMC10621750 DOI: 10.1111/tra.12836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 02/03/2022] [Accepted: 02/07/2022] [Indexed: 11/28/2022]
Abstract
Most enveloped viruses infect cells by binding receptors at the cell surface and undergo trafficking through the endocytic pathway to a compartment with the requisite conditions to trigger fusion with a host endosomal membrane. Broad categories of compartments in the endocytic pathway include early and late endosomes, which can be further categorized into subpopulations with differing rates of maturation and motility characteristics. Endocytic compartments have varying protein and lipid components, luminal ionic conditions and pH that provide uniquely hospitable environments for specific viruses to fuse. In order to characterize compartments that permit fusion, we studied the trafficking and fusion of viral particles pseudotyped with the vesicular stomatitis virus glycoprotein (VSV-G) on their surface and equipped with a novel pH sensor and a fluorescent content marker to measure pH, motion and fusion at the single particle level in live cells. We found that the VSV-G particles fuse predominantly from more acidic and more motile endosomes, and that a significant fraction of particles is trafficked to more static and less acidic endosomes that do not support their fusion. Moreover, the fusion-supporting endosomes undergo directed motion.
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Affiliation(s)
- Maya Cabot
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22903, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22903, USA
| | - Volker Kiessling
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22903, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22903, USA
| | - Judith M. White
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22903, USA
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22903, USA
| | - Lukas K. Tamm
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22903, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22903, USA
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22903, USA
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11
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Kreutzberger MA, Sobe R, Sauder AB, Chatterjee S, Wang F, Kiessling V, Conticello V, Frankel G, Kendall M, Scharf B, Egelman EH. Cryo-EM of bacterial flagellar filaments with screw-like surfaces and outer domain sheaths. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.2084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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12
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Odongo L, Kiessling V, White JM, Tamm LK. Lassa virus glycoprotein-mediated membrane fusion with endosomal model membranes. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.2347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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13
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Amos C, Kiessling V, Schenk N, Mohan R, Doyle CA, Kreutzberger AJ, Wang H, Levental KR, Levental I, Anantharam A, Tamm LK. Membrane order regulates SNARE mediated vesicle fusion in insulin-secreting cells. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.1281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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14
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Nyenhuis SB, Karandikar N, Kiessling V, Kreutzberger AJB, Thapa A, Liang B, Tamm LK, Cafiso DS. Conserved arginine residues in synaptotagmin 1 regulate fusion pore expansion through membrane contact. Nat Commun 2021; 12:761. [PMID: 33536412 PMCID: PMC7859215 DOI: 10.1038/s41467-021-21090-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 01/12/2021] [Indexed: 11/09/2022] Open
Abstract
Synaptotagmin 1 is a vesicle-anchored membrane protein that functions as the Ca2+ sensor for synchronous neurotransmitter release. In this work, an arginine containing region in the second C2 domain of synaptotagmin 1 (C2B) is shown to control the expansion of the fusion pore and thereby the concentration of neurotransmitter released. This arginine apex, which is opposite the Ca2+ binding sites, interacts with membranes or membrane reconstituted SNAREs; however, only the membrane interactions occur under the conditions in which fusion takes place. Other regions of C2B influence the fusion probability and kinetics but do not control the expansion of the fusion pore. These data indicate that the C2B domain has at least two distinct molecular roles in the fusion event, and the data are consistent with a model where the arginine apex of C2B positions the domain at the curved membrane surface of the expanding fusion pore.
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Affiliation(s)
- Sarah B Nyenhuis
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA.,Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD, USA
| | - Nakul Karandikar
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA.,Center for Membrane Biology, University of Virginia, Charlottesville, VA, USA
| | - Alex J B Kreutzberger
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA.,Center for Membrane Biology, University of Virginia, Charlottesville, VA, USA.,Department of Cell Biology, Harvard Medical School and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Anusa Thapa
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Binyong Liang
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA.,Center for Membrane Biology, University of Virginia, Charlottesville, VA, USA
| | - Lukas K Tamm
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA.,Center for Membrane Biology, University of Virginia, Charlottesville, VA, USA
| | - David S Cafiso
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA. .,Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA. .,Center for Membrane Biology, University of Virginia, Charlottesville, VA, USA.
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15
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Ward AE, Kiessling V, Pornillos O, White JM, Ganser-Pornillos BK, Tamm LK. HIV-Cell Membrane Fusion Intermediates are Restricted by Serinc3 and Serinc5. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.2030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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16
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Amos C, Kiessling V, Liang B, Tamm LK. Vesicle Membrane Order Controls Fusion by Determining Synaptobrevin's Conformation. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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17
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Lee J, Kreutzberger AJB, Odongo L, Nelson EA, Nyenhuis DA, Kiessling V, Liang B, Cafiso DS, White JM, Tamm LK. Ebola virus glycoprotein interacts with cholesterol to enhance membrane fusion and cell entry. Nat Struct Mol Biol 2021; 28:181-189. [PMID: 33462517 PMCID: PMC7992113 DOI: 10.1038/s41594-020-00548-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 12/07/2020] [Indexed: 12/14/2022]
Abstract
Cholesterol serves critical roles in enveloped virus fusion by modulating membrane properties. The glycoprotein (GP) of Ebola virus (EBOV) promotes fusion in the endosome, a process that requires the endosomal cholesterol transporter NPC1. However, the role of cholesterol in EBOV fusion is unclear. Here we show that cholesterol in GP-containing membranes enhances fusion and the membrane-proximal external region and transmembrane (MPER/TM) domain of GP interacts with cholesterol via several glycine residues in the GP2 TM domain, notably G660. Compared to wild-type (WT) counterparts, a G660L mutation caused a more open angle between MPER and TM domains in an MPER/TM construct, higher probability of stalling at hemifusion for GP2 proteoliposomes and lower cell entry of virus-like particles (VLPs). VLPs with depleted cholesterol show reduced cell entry, and VLPs produced under cholesterol-lowering statin conditions show less frequent entry than respective controls. We propose that cholesterol-TM interactions affect structural features of GP2, thereby facilitating fusion and cell entry.
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Affiliation(s)
- Jinwoo Lee
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA
| | - Alex J B Kreutzberger
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Laura Odongo
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Elizabeth A Nelson
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Cell Biology, University of Virginia, Charlottesville, VA, USA
| | - David A Nyenhuis
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Volker Kiessling
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Binyong Liang
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - David S Cafiso
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Judith M White
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Cell Biology, University of Virginia, Charlottesville, VA, USA
| | - Lukas K Tamm
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA.
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA.
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18
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Lee J, Kreutzberger AJ, Odongo L, Nelson EA, Nyenhuis D, Kiessling V, Liang B, Cafiso DS, White JM, Tamm LK. Ebola Virus Glycoprotein Interacts with Cholesterol to Enhance Membrane Fusion and Cell Entry. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.1317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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19
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Narahari AK, Kreutzberger AJB, Gaete PS, Chiu YH, Leonhardt SA, Medina CB, Jin X, Oleniacz PW, Kiessling V, Barrett PQ, Ravichandran KS, Yeager M, Contreras JE, Tamm LK, Bayliss DA. ATP and large signaling metabolites flux through caspase-activated Pannexin 1 channels. eLife 2021; 10:e64787. [PMID: 33410749 PMCID: PMC7806264 DOI: 10.7554/elife.64787] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/05/2021] [Indexed: 12/16/2022] Open
Abstract
Pannexin 1 (Panx1) is a membrane channel implicated in numerous physiological and pathophysiological processes via its ability to support release of ATP and other cellular metabolites for local intercellular signaling. However, to date, there has been no direct demonstration of large molecule permeation via the Panx1 channel itself, and thus the permselectivity of Panx1 for different molecules remains unknown. To address this, we expressed, purified, and reconstituted Panx1 into proteoliposomes and demonstrated that channel activation by caspase cleavage yields a dye-permeable pore that favors flux of anionic, large-molecule permeants (up to ~1 kDa). Large cationic molecules can also permeate the channel, albeit at a much lower rate. We further show that Panx1 channels provide a molecular pathway for flux of ATP and other anionic (glutamate) and cationic signaling metabolites (spermidine). These results verify large molecule permeation directly through caspase-activated Panx1 channels that can support their many physiological roles.
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Affiliation(s)
- Adishesh K Narahari
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Alex JB Kreutzberger
- Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Pablo S Gaete
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers New Jersey Medical SchoolNewarkUnited States
| | - Yu-Hsin Chiu
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Susan A Leonhardt
- Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Christopher B Medina
- Department of Microbiology, Immunology, and Cancer Biology, University of VirginiaCharlottesvilleUnited States
| | - Xueyao Jin
- Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Patrycja W Oleniacz
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Paula Q Barrett
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Kodi S Ravichandran
- Department of Microbiology, Immunology, and Cancer Biology, University of VirginiaCharlottesvilleUnited States
| | - Mark Yeager
- Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Jorge E Contreras
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers New Jersey Medical SchoolNewarkUnited States
| | - Lukas K Tamm
- Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Douglas A Bayliss
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
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20
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Kreutzberger AJB, Kiessling V, Doyle CA, Schenk N, Upchurch CM, Elmer-Dixon M, Ward AE, Preobraschenski J, Hussein SS, Tomaka W, Seelheim P, Kattan I, Harris M, Liang B, Kenworthy AK, Desai BN, Leitinger N, Anantharam A, Castle JD, Tamm LK. Distinct insulin granule subpopulations implicated in the secretory pathology of diabetes types 1 and 2. eLife 2020; 9:e62506. [PMID: 33164744 PMCID: PMC7738183 DOI: 10.7554/elife.62506] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 11/06/2020] [Indexed: 12/12/2022] Open
Abstract
Insulin secretion from β-cells is reduced at the onset of type-1 and during type-2 diabetes. Although inflammation and metabolic dysfunction of β-cells elicit secretory defects associated with type-1 or type-2 diabetes, accompanying changes to insulin granules have not been established. To address this, we performed detailed functional analyses of insulin granules purified from cells subjected to model treatments that mimic type-1 and type-2 diabetic conditions and discovered striking shifts in calcium affinities and fusion characteristics. We show that this behavior is correlated with two subpopulations of insulin granules whose relative abundance is differentially shifted depending on diabetic model condition. The two types of granules have different release characteristics, distinct lipid and protein compositions, and package different secretory contents alongside insulin. This complexity of β-cell secretory physiology establishes a direct link between granule subpopulation and type of diabetes and leads to a revised model of secretory changes in the diabetogenic process.
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Affiliation(s)
- Alex J B Kreutzberger
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Volker Kiessling
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Catherine A Doyle
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Noah Schenk
- Department of Pharmacology, University of MichiganAnn ArborUnited States
| | - Clint M Upchurch
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Margaret Elmer-Dixon
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Amanda E Ward
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Julia Preobraschenski
- Department of Neurobiology, Max Planck Institute for Biophysical ChemistryGöttingenGermany
- Cluster of Excellence in Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells and Institute for Auditory Neuroscience, University of GöttingenGöttingenGermany
| | - Syed S Hussein
- Department of Microbiology, University of VirginiaCharlottesvilleUnited States
| | - Weronika Tomaka
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Patrick Seelheim
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Iman Kattan
- Department of Neurobiology, Max Planck Institute for Biophysical ChemistryGöttingenGermany
| | - Megan Harris
- Department of Cell Biology, University of VirginiaCharlottesvilleUnited States
| | - Binyong Liang
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Anne K Kenworthy
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Bimal N Desai
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Norbert Leitinger
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Arun Anantharam
- Department of Pharmacology, University of MichiganAnn ArborUnited States
| | - J David Castle
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department of Cell Biology, University of VirginiaCharlottesvilleUnited States
| | - Lukas K Tamm
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
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21
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Ward AE, Kiessling V, Pornillos O, White JM, Ganser-Pornillos BK, Tamm LK. HIV-cell membrane fusion intermediates are restricted by Serincs as revealed by cryo-electron and TIRF microscopy. J Biol Chem 2020; 295:15183-15195. [PMID: 32788212 PMCID: PMC7650252 DOI: 10.1074/jbc.ra120.014466] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/19/2020] [Indexed: 12/13/2022] Open
Abstract
To enter a cell and establish infection, HIV must first fuse its lipid envelope with the host cell plasma membrane. Whereas the process of HIV membrane fusion can be tracked by fluorescence microscopy, the 3D configuration of proteins and lipids at intermediate steps can only be resolved with cryo-electron tomography (cryoET). However, cryoET of whole cells is technically difficult. To overcome this problem, we have adapted giant plasma membrane vesicles (or blebs) from native cell membranes expressing appropriate receptors as targets for fusion with HIV envelope glycoprotein-expressing pseudovirus particles with and without Serinc host restriction factors. The fusion behavior of these particles was probed by TIRF microscopy on bleb-derived supported membranes. Timed snapshots of fusion of the same particles with blebs were examined by cryo-ET. The combination of these methods allowed us to characterize the structures of various intermediates on the fusion pathway and showed that when Serinc3 or Serinc5 (but not Serinc2) were present, later fusion products were more prevalent, suggesting that Serinc3/5 act at multiple steps to prevent progression to full fusion. In addition, the antifungal amphotericin B reversed Serinc restriction, presumably by intercalation into the fusing membranes. Our results provide a highly detailed view of Serinc restriction of HIV-cell membrane fusion and thus extend current structural and functional information on Serinc as a lipid-binding protein.
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Affiliation(s)
- Amanda E Ward
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Owen Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Judith M White
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Barbie K Ganser-Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia, USA.
| | - Lukas K Tamm
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia, USA; Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA.
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22
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Bendahmane M, Morales A, Kreutzberger AJB, Schenk NA, Mohan R, Bakshi S, Philippe JM, Zhang S, Kiessling V, Tamm LK, Giovannucci DR, Jenkins PM, Anantharam A. Synaptotagmin-7 enhances calcium-sensing of chromaffin cell granules and slows discharge of granule cargos. J Neurochem 2020; 154:598-617. [PMID: 32058590 DOI: 10.1111/jnc.14986] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 02/04/2020] [Accepted: 02/07/2020] [Indexed: 12/30/2022]
Abstract
Synaptotagmin-7 (Syt-7) is one of two major calcium sensors for exocytosis in adrenal chromaffin cells, the other being synaptotagmin-1 (Syt-1). Despite a broad appreciation for the importance of Syt-7, questions remain as to its localization, function in mediating discharge of dense core granule cargos, and role in triggering release in response to physiological stimulation. These questions were addressed using two distinct experimental preparations-mouse chromaffin cells lacking endogenous Syt-7 (KO cells) and a reconstituted system employing cell-derived granules expressing either Syt-7 or Syt-1. First, using immunofluorescence imaging and subcellular fractionation, it is shown that Syt-7 is widely distributed in organelles, including dense core granules. Total internal reflection fluorescence (TIRF) imaging demonstrates that the kinetics and probability of granule fusion in Syt-7 KO cells stimulated by a native secretagogue, acetylcholine, are markedly lower than in WT cells. When fusion is observed, fluorescent cargo proteins are discharged more rapidly when only Syt-1 is available to facilitate release. To determine the extent to which the aforementioned results are attributable purely to Syt-7, granules expressing only Syt-7 or Syt-1 were triggered to fuse on planar supported bilayers bearing plasma membrane SNARE proteins. Here, as in cells, Syt-7 confers substantially greater calcium sensitivity to granule fusion than Syt-1 and slows the rate at which cargos are released. Overall, this study demonstrates that by virtue of its high affinity for calcium and effects on fusion pore expansion, Syt-7 plays a central role in regulating secretory output from adrenal chromaffin cells.
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Affiliation(s)
- Mounir Bendahmane
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | - Alina Morales
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | - Alex J B Kreutzberger
- Center for Membrane and Cell Physiology and Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Noah A Schenk
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | - Ramkumar Mohan
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | - Shreeya Bakshi
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | - Julie M Philippe
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | - Shuang Zhang
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | - Volker Kiessling
- Center for Membrane and Cell Physiology and Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Lukas K Tamm
- Center for Membrane and Cell Physiology and Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - David R Giovannucci
- Department of Neuroscience, University of Toledo Medical School, Toledo, OH, USA
| | - Paul M Jenkins
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | - Arun Anantharam
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
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23
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Liang Q, Kiessling V, Liang B, Tamm LK, Cafiso DS. Complexin 1 and Synaptotagmin 1 Compete for Membrane Binding in a PIP2 Dependent Manner. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.3015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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24
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Narahari AK, Kreutzberger AJ, Leonhardt S, Jin X, Pauchard P, Medina CB, Kiessling V, Ravichandran K, Contreras JE, Tamm LK, Yeager M, Bayliss DA. Permeation Properties of Purified Pannexin 1 Channels in Proteoliposomes. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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25
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Amos C, Schenk N, Kiessling V, Kreutzberger AJ, Tomaka W, Bendahmane M, Seki H, Niko Y, Klymchenko AS, Tamm LK, Anantharam A. Plasma Membrane Order Regulates Insulin Granule Exocytosis. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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26
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Liang B, Stashower J, Kreutzberger AJ, Kiessling V, Tamm LK. Binding of Complexin to t-SNARE Complex is Mediated by SNAP25. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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27
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Kiessling V, Kreutzberger AJ, Liang B, Nyenhuis SB, Seelheim P, Castle JD, Cafiso DS, Tamm LK. How Ca2+ And Synaptotagmin Trigger Snare-Mediated Membrane Fusion. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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28
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Schenk NA, Kreutzberger AJ, Harris MT, Doyle CA, Seelheim P, Liang B, Kiessling V, Anantharam A, Tamm LK, Castle JD. Two Populations of Insulin Granules with Distinct Fusion Properties are Maintained by ABC Transporters ABCG1 and ABCA1. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.1701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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29
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Kiessling V, Kreutzberger AJB, Liang B, Nyenhuis SB, Seelheim P, Castle JD, Cafiso DS, Tamm LK. A molecular mechanism for calcium-mediated synaptotagmin-triggered exocytosis. Nat Struct Mol Biol 2018; 25:911-917. [PMID: 30291360 PMCID: PMC6176490 DOI: 10.1038/s41594-018-0130-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 07/31/2018] [Indexed: 12/01/2022]
Abstract
The regulated exocytotic release of neurotransmitter and hormones is accomplished by a complex protein machinery consisting in its core of SNARE proteins and the calcium sensor synaptotagmin-1. We propose a mechanism where the lipid membrane is intimately involved in coupling calcium sensing to release. We demonstrate that fusion of dense core vesicles, derived from rat PC12 cells is strongly linked to the angle between the cytoplasmic domain of the SNARE complex and the plane of the target membrane. We propose that, as this tilt angle increases, force is exerted on the SNARE transmembrane domains to drive the merger of the two bilayers. The tilt angle dramatically increases upon calcium-mediated binding of synaptotagmin to membranes, strongly depends on the surface electrostatics of the membrane, and is strictly coupled to lipid order of the target membrane.
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Affiliation(s)
- Volker Kiessling
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA. .,Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA.
| | - Alex J B Kreutzberger
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA.,Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Binyong Liang
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA.,Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Sarah B Nyenhuis
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Patrick Seelheim
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA.,Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - J David Castle
- Department of Cell Biology, University of Virginia, Charlottesville, VA, USA
| | - David S Cafiso
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Lukas K Tamm
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA.,Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
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30
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Sanganna Gari RR, Seelheim P, Marsh B, Kiessling V, Creutz CE, Tamm LK. Quaternary structure of the small amino acid transporter OprG from Pseudomonas aeruginosa. J Biol Chem 2018; 293:17267-17277. [PMID: 30237175 DOI: 10.1074/jbc.ra118.004461] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 09/13/2018] [Indexed: 02/01/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen that causes nosocomial infections. The P. aeruginosa outer membrane contains specific porins that enable substrate uptake, with the outer membrane protein OprG facilitating transport of small, uncharged amino acids. However, the pore size of an eight-stranded β-barrel monomer of OprG is too narrow to accommodate even the smallest transported amino acid, glycine, raising the question of how OprG facilitates amino acid uptake. Pro-92 of OprG is critically important for amino acid transport, with a P92A substitution inhibiting transport and the NMR structure of this variant revealing that this substitution produces structural changes in the barrel rim and restricts loop motions. OprG may assemble into oligomers in the outer membrane (OM) whose subunit interfaces could form a transport channel. Here, we explored the contributions of the oligomeric state and the extracellular loops to OprG's function. Using chemical cross-linking to determine the oligomeric structures of both WT and P92A OprG in native outer membranes and atomic force microscopy, and single-molecule fluorescence of the purified proteins reconstituted into lipid bilayers, we found that both protein variants form oligomers, supporting the notion that subunit interfaces in the oligomer could provide a pathway for amino acid transport. Furthermore, performing transport assays with loop-deleted OprG variants, we found that these variants also can transport small amino acids, indicating that the loops are not solely responsible for substrate transport. We propose that OprG functions as an oligomer and that conformational changes in the barrel-loop region might be crucial for its activity.
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Affiliation(s)
| | - Patrick Seelheim
- From the Department of Molecular Physiology and Biological Physics, Center for Cell and Membrane Physiology and
| | - Brendan Marsh
- the Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 OWA, United Kingdom
| | - Volker Kiessling
- From the Department of Molecular Physiology and Biological Physics, Center for Cell and Membrane Physiology and
| | - Carl E Creutz
- the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908 and
| | - Lukas K Tamm
- From the Department of Molecular Physiology and Biological Physics, Center for Cell and Membrane Physiology and
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31
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Liang B, JB Kreutzberger A, Zdanowicz R, Kiessling V, Cafiso DS, Tamm LK. Complexin Binding to Membranes and Acceptor t-SNARE Complex Explains its Clamping and Stimulatory Effects on Fusion. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.3321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Blackburn MR, Hubbard C, Kiessling V, Bi Y, Kloss B, Tamm LK, Zimmer J. Distinct reaction mechanisms for hyaluronan biosynthesis in different kingdoms of life. Glycobiology 2018; 28:108-121. [PMID: 29190396 PMCID: PMC6192386 DOI: 10.1093/glycob/cwx096] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 11/17/2017] [Accepted: 11/22/2017] [Indexed: 12/19/2022] Open
Abstract
Hyaluronan (HA) is an acidic high molecular weight cell surface polysaccharide ubiquitously expressed by vertebrates, some pathogenic bacteria and even viruses. HA modulates many essential physiological processes and is implicated in numerous pathological conditions ranging from autoimmune diseases to cancer. In various pathogens, HA functions as a non-immunogenic surface polymer that reduces host immune responses. It is a linear polymer of strictly alternating glucuronic acid and N-acetylglucosamine units synthesized by HA synthase (HAS), a membrane-embedded family-2 glycosyltransferase. The enzyme synthesizes HA and secretes the polymer through a channel formed by its own membrane-integrated domain. To reveal how HAS achieves these tasks, we determined the biologically functional units of bacterial and viral HAS in a lipid bilayer environment by co-immunoprecipitation, single molecule fluorescence photobleaching, and site-specific cross-linking analyses. Our results demonstrate that bacterial HAS functions as an obligate homo-dimer with two functional HAS copies required for catalytic activity. In contrast, the viral enzyme, closely related to vertebrate HAS, functions as a monomer. Using site-specific cross-linking, we identify the dimer interface of bacterial HAS and show that the enzyme uses a reaction mechanism distinct from viral HAS that necessitates a dimeric assembly.
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Affiliation(s)
- Matthew R Blackburn
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA
| | - Caitlin Hubbard
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
| | - Yunchen Bi
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA
| | - Brian Kloss
- Center on Membrane Protein Production and Analysis (COMPPÅ), New York Structural Biology Center (NYSBC), 89 Convent Avenue, New York, NY 10027, USA
| | - Lukas K Tamm
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
| | - Jochen Zimmer
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA
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Reddy Sanganna Gari R, Seelheim P, Marsh B, Kiessling V, Creutz C, Tamm L. Quaternary Structure of Small Amino Acids Transporter OprG of Pseudomonas aeruginosa. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.1316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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34
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Lee J, Kreutzberger AJ, Nyenhuis DA, Nelson EA, Kiessling V, Cafiso DS, White JM, Tamm LK. Ebola Virus Spike Glycoprotein Recruits Cholesterol for Efficient Fusion. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.3305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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35
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Kreutzberger AJB, Kiessling V, Liang B, Yang ST, Castle JD, Tamm LK. Asymmetric Phosphatidylethanolamine Distribution Controls Fusion Pore Lifetime and Probability. Biophys J 2017; 113:1912-1915. [PMID: 29037600 DOI: 10.1016/j.bpj.2017.09.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/11/2017] [Accepted: 09/13/2017] [Indexed: 01/18/2023] Open
Abstract
Little attention has been given to how the asymmetric lipid distribution of the plasma membrane might facilitate fusion pore formation during exocytosis. Phosphatidylethanolamine (PE), a cone-shaped phospholipid, is predominantly located in the inner leaflet of the plasma membrane and has been proposed to promote membrane deformation and stabilize fusion pores during exocytotic events. To explore this possibility, we modeled exocytosis using plasma membrane SNARE-containing planar-supported bilayers and purified neuroendocrine dense core vesicles (DCVs) as fusion partners, and we examined how different PE distributions between the two leaflets of the supported bilayers affected SNARE-mediated fusion. Using total internal reflection fluorescence microscopy, the fusion of single DCVs with the planar-supported bilayer was monitored by observing DCV-associated neuropeptide Y tagged with a fluorescent protein. The time-dependent line shape of the fluorescent signal enables detection of DCV docking, fusion-pore opening, and vesicle collapse into the planar membrane. Four different distributions of PE in the planar bilayer mimicking the plasma membrane were examined: exclusively in the leaflet facing the DCVs; exclusively in the opposite leaflet; equally distributed in both leaflets; and absent from both leaflets. With PE in the leaflet facing the DCVs, overall fusion was most efficient and the extended fusion pore lifetime (0.7 s) enabled notable detection of content release preceding vesicle collapse. All other PE distributions decreased fusion efficiency, altered pore lifetime, and reduced content release. With PE exclusively in the opposite leaflet, resolution of pore opening and content release was lost.
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Affiliation(s)
- Alex J B Kreutzberger
- Department of Molecular Physiology and Biological Physics, Center for Cell and Membrane Physiology at the University of Virginia, Charlottesville, Virginia
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics, Center for Cell and Membrane Physiology at the University of Virginia, Charlottesville, Virginia
| | - Binyong Liang
- Department of Molecular Physiology and Biological Physics, Center for Cell and Membrane Physiology at the University of Virginia, Charlottesville, Virginia
| | - Sung-Tae Yang
- Department of Molecular Physiology and Biological Physics, Center for Cell and Membrane Physiology at the University of Virginia, Charlottesville, Virginia
| | - J David Castle
- Department of Cell Biology, Center for Cell and Membrane Physiology at the University of Virginia, Charlottesville, Virginia
| | - Lukas K Tamm
- Department of Molecular Physiology and Biological Physics, Center for Cell and Membrane Physiology at the University of Virginia, Charlottesville, Virginia.
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36
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Kreutzberger AJB, Kiessling V, Liang B, Seelheim P, Jakhanwal S, Jahn R, Castle JD, Tamm LK. Reconstitution of calcium-mediated exocytosis of dense-core vesicles. Sci Adv 2017; 3:e1603208. [PMID: 28776026 PMCID: PMC5517108 DOI: 10.1126/sciadv.1603208] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 06/15/2017] [Indexed: 05/11/2023]
Abstract
Regulated exocytosis is a process by which neurotransmitters, hormones, and secretory proteins are released from the cell in response to elevated levels of calcium. In cells, secretory vesicles are targeted to the plasma membrane, where they dock, undergo priming, and then fuse with the plasma membrane in response to calcium. The specific roles of essential proteins and how calcium regulates progression through these sequential steps are currently incompletely resolved. We have used purified neuroendocrine dense-core vesicles and artificial membranes to reconstruct in vitro the serial events that mimic SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor)-dependent membrane docking and fusion during exocytosis. Calcium recruits these vesicles to the target membrane aided by the protein CAPS (calcium-dependent activator protein for secretion), whereas synaptotagmin catalyzes calcium-dependent fusion; both processes are dependent on phosphatidylinositol 4,5-bisphosphate. The soluble proteins Munc18 and complexin-1 are necessary to arrest vesicles in a docked state in the absence of calcium, whereas CAPS and/or Munc13 are involved in priming the system for an efficient fusion reaction.
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Affiliation(s)
- Alex J. B. Kreutzberger
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
| | - Volker Kiessling
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
| | - Binyong Liang
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
| | - Patrick Seelheim
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
| | - Shrutee Jakhanwal
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Reinhard Jahn
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - J. David Castle
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908, USA
| | - Lukas K. Tamm
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
- Corresponding author.
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Yang ST, Kreutzberger AJB, Kiessling V, Ganser-Pornillos BK, White JM, Tamm LK. HIV virions sense plasma membrane heterogeneity for cell entry. Sci Adv 2017; 3:e1700338. [PMID: 28782011 PMCID: PMC5489272 DOI: 10.1126/sciadv.1700338] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 05/12/2017] [Indexed: 05/20/2023]
Abstract
It has been proposed that cholesterol in host cell membranes plays a pivotal role for cell entry of HIV. However, it remains largely unknown why virions prefer cholesterol-rich heterogeneous membranes to uniformly fluid membranes for membrane fusion. Using giant plasma membrane vesicles containing cholesterol-rich ordered and cholesterol-poor fluid lipid domains, we demonstrate that the HIV receptor CD4 is substantially sequestered into ordered domains, whereas the co-receptor CCR5 localizes preferentially at ordered/disordered domain boundaries. We also show that HIV does not fuse from within ordered regions of the plasma membrane but rather at their boundaries. Ordered/disordered lipid domain coexistence is not required for HIV attachment but is a prerequisite for successful fusion. We propose that HIV virions sense and exploit membrane discontinuities to gain entry into cells. This study provides surprising answers to the long-standing question about the roles of cholesterol and ordered lipid domains in cell entry of HIV and perhaps other enveloped viruses.
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Affiliation(s)
- Sung-Tae Yang
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
| | - Alex J. B. Kreutzberger
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
| | - Volker Kiessling
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
| | - Barbie K. Ganser-Pornillos
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
| | - Judith M. White
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908, USA
| | - Lukas K. Tamm
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
- Corresponding author.
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Zdanowicz R, Kreutzberger A, Liang B, Kiessling V, Tamm LK, Cafiso DS. Complexin Binding to Membranes and Acceptor t-SNAREs Explains Its Clamping Effect on Fusion. Biophys J 2017; 113:1235-1250. [PMID: 28456331 DOI: 10.1016/j.bpj.2017.04.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 03/31/2017] [Accepted: 04/04/2017] [Indexed: 02/07/2023] Open
Abstract
Complexin-1 is a SNARE effector protein that decreases spontaneous neurotransmitter release and enhances evoked release. Complexin binds to the fully assembled four-helical neuronal SNARE core complex as revealed in competing molecular models derived from x-ray crystallography. Presently, it is unclear how complexin binding to the postfusion complex accounts for its effects upon spontaneous and evoked release in vivo. Using a combination of spectroscopic and imaging methods, we characterize in molecular detail how complexin binds to the 1:1 plasma membrane t-SNARE complex of syntaxin-1a and SNAP-25 while simultaneously binding the lipid bilayer at both its N- and C-terminal ends. These interactions are cooperative, and binding to the prefusion acceptor t-SNARE complex is stronger than to the postfusion core complex. This complexin interaction reduces the affinity of synaptobrevin-2 for the 1:1 complex, thereby retarding SNARE assembly and vesicle docking in vitro. The results provide the basis for molecular models that account for the observed clamping effect of complexin beginning with the acceptor t-SNARE complex and the subsequent activation of the clamped complex by Ca2+ and synaptotagmin.
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Affiliation(s)
- Rafal Zdanowicz
- Department of Chemistry, University of Virginia, Charlottesville, Virginia; Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia
| | - Alex Kreutzberger
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia; Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia
| | - Binyong Liang
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia; Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia
| | - Volker Kiessling
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia; Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia
| | - Lukas K Tamm
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia; Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia.
| | - David S Cafiso
- Department of Chemistry, University of Virginia, Charlottesville, Virginia; Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia.
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Kiessling V, Liang B, Kreutzberger AJB, Tamm LK. Planar Supported Membranes with Mobile SNARE Proteins and Quantitative Fluorescence Microscopy Assays to Study Synaptic Vesicle Fusion. Front Mol Neurosci 2017; 10:72. [PMID: 28360838 PMCID: PMC5352703 DOI: 10.3389/fnmol.2017.00072] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/03/2017] [Indexed: 12/31/2022] Open
Abstract
Synaptic vesicle membrane fusion, the process by which neurotransmitter gets released at the presynaptic membrane is mediated by a complex interplay between proteins and lipids. The realization that the lipid bilayer is not just a passive environment where other molecular players like SNARE proteins act, but is itself actively involved in the process, makes the development of biochemical and biophysical assays particularly challenging. We summarize in vitro assays that use planar supported membranes and fluorescence microscopy to address some of the open questions regarding the molecular mechanisms of SNARE-mediated membrane fusion. Most of the assays discussed in this mini-review were developed in our lab over the last 15 years. We emphasize the sample requirements that we found are important for the successful application of these methods.
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Affiliation(s)
- Volker Kiessling
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesville, VA, USA
| | - Binyong Liang
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesville, VA, USA
| | - Alex J B Kreutzberger
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesville, VA, USA
| | - Lukas K Tamm
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesville, VA, USA
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Kreutzberger A, Kiessling V, Liang B, Seelheim P, Castle JD, Tamm LK. Calcium-Mediated Docking and Fusion of Purified Dense Core Vesicles with Reconstituted Membranes. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.2147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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41
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Yang ST, Kiessling V, Tamm LK. HIV Entry: Receptors Cooperate with Membrane Domain Boundaries to form Entry Sites in Host Cells. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Yang ST, Lim SI, Kiessling V, Kwon I, Tamm LK. Site-specific fluorescent labeling to visualize membrane translocation of a myristoyl switch protein. Sci Rep 2016; 6:32866. [PMID: 27605302 PMCID: PMC5015116 DOI: 10.1038/srep32866] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/16/2016] [Indexed: 12/20/2022] Open
Abstract
Fluorescence approaches have been widely used for elucidating the dynamics of protein-membrane interactions in cells and model systems. However, non-specific multi-site fluorescent labeling often results in a loss of native structure and function, and single cysteine labeling is not feasible when native cysteines are required to support a protein's folding or catalytic activity. Here, we develop a method using genetic incorporation of non-natural amino acids and bio-orthogonal chemistry to site-specifically label with a single fluorescent small molecule or protein the myristoyl-switch protein recoverin, which is involved in rhodopsin-mediated signaling in mammalian visual sensory neurons. We demonstrate reversible Ca(2+)-responsive translocation of labeled recoverin to membranes and show that recoverin favors membranes with negative curvature and high lipid fluidity in complex heterogeneous membranes, which confers spatio-temporal control over down-stream signaling events. The site-specific orthogonal labeling technique is promising for structural, dynamical, and functional studies of many lipid-anchored membrane protein switches.
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Affiliation(s)
- Sung-Tae Yang
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Sung In Lim
- Department of Chemical Engineering, University of Virginia, Charlottesville, VA 22904, USA
| | - Volker Kiessling
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Inchan Kwon
- Department of Chemical Engineering, University of Virginia, Charlottesville, VA 22904, USA
- School of Materials Science and Engineering, and Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Lukas K. Tamm
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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Kreutzberger AJB, Liang B, Kiessling V, Tamm LK. Assembly and Comparison of Plasma Membrane SNARE Acceptor Complexes. Biophys J 2016; 110:2147-50. [PMID: 27178662 DOI: 10.1016/j.bpj.2016.04.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 03/11/2016] [Accepted: 04/08/2016] [Indexed: 12/16/2022] Open
Abstract
Neuronal exocytotic membrane fusion occurs on a fast timescale and is dependent on interactions between the vesicle SNARE synaptobrevin-2 and the plasma membrane SNAREs syntaxin-1a and SNAP-25 with a 1:1:1 stoichiometry. Reproducing fast fusion rates as observed in cells by reconstitution in vitro has been hindered by the spontaneous assembly of a 2:1 syntaxin-1a:SNAP-25 complex on target membranes that kinetically alters the binding of synaptobrevin-2. Previously, an artificial SNARE acceptor complex consisting of 1:1:1 syntaxin-1a(residues 183-288):SNAP-25:syb(residues 49-96) was found to greatly accelerate the rates of lipid mixing of reconstituted target and vesicle SNARE proteoliposomes. Here we present two (to our knowledge) new procedures to assemble membrane-bound 1:1 SNARE acceptor complexes that produce fast and efficient fusion without the need of the syb(49-96) peptide. In the first procedure, syntaxin-1a is purified in a strictly monomeric form and subsequently assembled with SNAP-25 in detergent with the correct 1:1 stoichiometry. In the second procedure, monomeric syntaxin-1a and dodecylated (d-)SNAP-25 are separately reconstituted into proteoliposomes and subsequently assembled in the plane of merged target lipid bilayers. Examining single particle fusion between synaptobrevin-2 proteoliposomes and planar-supported bilayers containing the two different SNARE acceptor complexes revealed similar fast rates of fusion. Changing the stoichiometry of syntaxin-1a and d-SNAP-25 in the target bilayer had significant effects on docking, but little effect on the rates of synaptobrevin-2 proteoliposome fusion.
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Affiliation(s)
- Alex J B Kreutzberger
- Center for Membrane and Cell Physiology and Department of Molecular Physiology & Biological Physics, University of Virginia, Charlottesville, Virginia
| | - Binyong Liang
- Center for Membrane and Cell Physiology and Department of Molecular Physiology & Biological Physics, University of Virginia, Charlottesville, Virginia
| | - Volker Kiessling
- Center for Membrane and Cell Physiology and Department of Molecular Physiology & Biological Physics, University of Virginia, Charlottesville, Virginia
| | - Lukas K Tamm
- Center for Membrane and Cell Physiology and Department of Molecular Physiology & Biological Physics, University of Virginia, Charlottesville, Virginia.
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Kiessling V, Liang B, Tamm LK. FLIC Microscopy Reveals Different Conformational States of Syntaxin 1a in Supported Lipid Bilayers. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.1365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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46
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Kreutzberger AJ, Liang B, Kiessling V, Tamm LK. Assembly and Comparison of Plasma Membrane SNARE Acceptor Complexes. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.1378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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47
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Yang ST, Kiessling V, Simmons JA, White JM, Tamm LK. HIV gp41-mediated membrane fusion occurs at edges of cholesterol-rich lipid domains. Nat Chem Biol 2015; 11:424-31. [PMID: 25915200 PMCID: PMC4433777 DOI: 10.1038/nchembio.1800] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 03/25/2015] [Indexed: 12/31/2022]
Abstract
Lipid rafts in plasma membranes have emerged as possible platforms for entry of HIV and other viruses into cells. However, how lipid phase heterogeneity contributes to viral entry is little known due to the fine-grained and still poorly understood complexity of biological membranes. We used model systems mimicking HIV envelopes and T-cell membranes and showed that raft-like (Lo phase) lipid domains are necessary and sufficient for efficient membrane targeting and fusion. Interestingly, membrane binding and fusion was low in homogeneous Ld and Lo phase membranes, indicating that lipid phase heterogeneity is essential. The HIV fusion peptide preferentially targeted to Lo/Ld boundary regions and promoted full fusion at the interface between ordered and disordered lipids. Ld phase vesicles proceeded only to hemifusion. Thus, we propose that the edges, but not the areas of raft-like ordered lipid domains are vital for HIV entry and membrane fusion.
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Affiliation(s)
- Sung-Tae Yang
- 1] Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA. [2] Center for Membrane Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Volker Kiessling
- 1] Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA. [2] Center for Membrane Biology, University of Virginia, Charlottesville, Virginia, USA
| | - James A Simmons
- 1] Center for Membrane Biology, University of Virginia, Charlottesville, Virginia, USA. [2] Department of Cell Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Judith M White
- 1] Center for Membrane Biology, University of Virginia, Charlottesville, Virginia, USA. [2] Department of Cell Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Lukas K Tamm
- 1] Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA. [2] Center for Membrane Biology, University of Virginia, Charlottesville, Virginia, USA
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Abstract
Successful reconstitutions of SNARE-mediated intracellular membrane fusion have been achieved in bulk fusion assays since 1998 and in single liposome fusion assays since 2004. Especially in neuronal presynaptic SNARE-mediated exocytosis, fusion is controlled by numerous accessory proteins, of which some functions have also been reconstituted in vitro. The development of and results obtained with two fundamentally different single liposome fusion assays, namely liposome-to-supported membrane and liposome-to-liposome, are reviewed. Both assays distinguish between liposome docking and fusion steps of the overall fusion reaction and both assays are capable of resolving hemi-and full-fusion intermediates and end states. They have opened new windows for elucidating the mechanisms of these fundamentally important cellular reactions with unprecedented time and molecular resolution. Although many of the molecular actors in this process have been discovered, we have only scratched the surface of looking at their fascinating plays, interactions, and choreographies that lead to vesicle traffic as well as neurotransmitter and hormone release in the cell.
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Affiliation(s)
- Volker Kiessling
- Center for Membrane Biology and Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Binyong Liang
- Center for Membrane Biology and Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Lukas K Tamm
- Center for Membrane Biology and Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
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49
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Liang B, Kiessling V, Dawidowski D, Cafiso DS, Tamm LK. Prefusion Structures of Lipid-Bound SNARE Proteins Suggest Folding Pathways of Trans-SNARE Complex. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.1937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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50
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Kiessling V, Lu B, Tamm LK, Cafiso DS. Chasing the Functional Asymmetry between C2A and C2B in Full-Length Synaptotagmin 1 during Ca2+-Dependent Membrane Binding. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.2242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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