1
|
Zhu M, Xu H, Jin Y, Kong X, Xu B, Liu Y, Yu H. Synaptotagmin-1 undergoes phase separation to regulate its calcium-sensitive oligomerization. J Cell Biol 2024; 223:e202311191. [PMID: 38980206 PMCID: PMC11232894 DOI: 10.1083/jcb.202311191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 04/17/2024] [Accepted: 06/11/2024] [Indexed: 07/10/2024] Open
Abstract
Synaptotagmin-1 (Syt1) is a calcium sensor that regulates synaptic vesicle fusion in synchronous neurotransmitter release. Syt1 interacts with negatively charged lipids and the SNARE complex to control the fusion event. However, it remains incompletely understood how Syt1 mediates Ca2+-trigged synaptic vesicle fusion. Here, we discovered that Syt1 undergoes liquid-liquid phase separation (LLPS) to form condensates both in vitro and in living cells. Syt1 condensates play a role in vesicle attachment to the PM and efficiently recruit SNAREs and complexin, which may facilitate the downstream synaptic vesicle fusion. We observed that Syt1 condensates undergo a liquid-to-gel-like phase transition, reflecting the formation of Syt1 oligomers. The phase transition can be blocked or reversed by Ca2+, confirming the essential role of Ca2+ in Syt1 oligomer disassembly. Finally, we showed that the Syt1 mutations causing Syt1-associated neurodevelopmental disorder impair the Ca2+-driven phase transition. These findings reveal that Syt1 undergoes LLPS and a Ca2+-sensitive phase transition, providing new insights into Syt1-mediated vesicle fusion.
Collapse
Affiliation(s)
- Min Zhu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Han Xu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Yulei Jin
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Xiaoxu Kong
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Bingkuan Xu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| |
Collapse
|
2
|
Duan M, Gao G, Lin A, Mackey EJ, Banfield DK, Merz AJ. SM protein Sly1 and a SNARE Habc domain promote membrane fusion through multiple mechanisms. J Cell Biol 2024; 223:e202001034. [PMID: 38478017 PMCID: PMC10943372 DOI: 10.1083/jcb.202001034] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 12/20/2023] [Accepted: 02/22/2024] [Indexed: 03/17/2024] Open
Abstract
SM proteins including Sly1 are essential cofactors of SNARE-mediated membrane fusion. Using SNARE and Sly1 mutants and chemically defined in vitro assays, we separate and assess proposed mechanisms through which Sly1 augments fusion: (i) opening the closed conformation of the Qa-SNARE Sed5; (ii) close-range tethering of vesicles to target organelles, mediated by the Sly1-specific regulatory loop; and (iii) nucleation of productive trans-SNARE complexes. We show that all three mechanisms are important and operate in parallel, and that close-range tethering promotes trans-complex assembly when cis-SNARE assembly is a competing process. Further, we demonstrate that the autoinhibitory N-terminal Habc domain of Sed5 has at least two positive activities: it is needed for correct Sed5 localization, and it directly promotes Sly1-dependent fusion. "Split Sed5," with Habc presented solely as a soluble fragment, can function both in vitro and in vivo. Habc appears to facilitate events leading to lipid mixing rather than promoting opening or stability of the fusion pore.
Collapse
Affiliation(s)
- Mengtong Duan
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Guanbin Gao
- The Division of Life Science, The Hong Kong University of Science and Technology, Kowloon, Hong Kong
| | - Ariel Lin
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Emma J. Mackey
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - David K. Banfield
- The Division of Life Science, The Hong Kong University of Science and Technology, Kowloon, Hong Kong
| | - Alexey J. Merz
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| |
Collapse
|
3
|
Duan M, Plemel RL, Takenaka T, Lin A, Delgado BM, Nattermann U, Nickerson DP, Mima J, Miller EA, Merz AJ. SNARE chaperone Sly1 directly mediates close-range vesicle tethering. J Cell Biol 2024; 223:e202001032. [PMID: 38478018 PMCID: PMC10943277 DOI: 10.1083/jcb.202001032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 12/20/2023] [Accepted: 02/22/2024] [Indexed: 03/17/2024] Open
Abstract
The essential Golgi protein Sly1 is a member of the Sec1/mammalian Unc-18 (SM) family of SNARE chaperones. Sly1 was originally identified through remarkable gain-of-function alleles that bypass requirements for diverse vesicle tethering factors. Employing genetic analyses and chemically defined reconstitutions of ER-Golgi fusion, we discovered that a loop conserved among Sly1 family members is not only autoinhibitory but also acts as a positive effector. An amphipathic lipid packing sensor (ALPS)-like helix within the loop directly binds high-curvature membranes. Membrane binding is required for relief of Sly1 autoinhibition and also allows Sly1 to directly tether incoming vesicles to the Qa-SNARE on the target organelle. The SLY1-20 mutation bypasses requirements for diverse tethering factors but loses this ability if the tethering activity is impaired. We propose that long-range tethers, including Golgins and multisubunit tethering complexes, hand off vesicles to Sly1, which then tethers at close range to initiate trans-SNARE complex assembly and fusion in the early secretory pathway.
Collapse
Affiliation(s)
- Mengtong Duan
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Rachael L. Plemel
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | | | - Ariel Lin
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Department of Biology, California State University, San Bernardino, CA, USA
| | | | - Una Nattermann
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Biophysics, Structure, and Design Graduate Program, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
| | | | - Joji Mima
- Institute for Protein Research, Osaka University, Osaka, Japan
| | | | - Alexey J. Merz
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| |
Collapse
|
4
|
Liu F, He R, Xu X, Zhu M, Yu H, Liu Y. Munc18c accelerates SNARE-dependent membrane fusion in the presence of regulatory proteins α-SNAP and NSF. J Biol Chem 2024; 300:105782. [PMID: 38395304 PMCID: PMC10959665 DOI: 10.1016/j.jbc.2024.105782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 01/23/2024] [Accepted: 02/18/2024] [Indexed: 02/25/2024] Open
Abstract
Intracellular vesicle fusion is driven by the soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and their cofactors, including Sec1/Munc18 (SM), α-SNAP, and NSF. α-SNAP and NSF play multiple layers of regulatory roles in the SNARE assembly, disassembling the cis-SNARE complex and the prefusion SNARE complex. How SM proteins coupled with NSF and α-SNAP regulate SNARE-dependent membrane fusion remains incompletely understood. Munc18c, an SM protein involved in the exocytosis of the glucose transporter GLUT4, binds and activates target (t-) SNAREs to accelerate the fusion reaction through a SNARE-like peptide (SLP). Here, using an in vitro reconstituted system, we discovered that α-SNAP blocks the GLUT4 SNAREs-mediated membrane fusion. Munc18c interacts with t-SNAREs to displace α-SNAP, which overcomes the fusion inhibition. Furthermore, Munc18c shields the trans-SNARE complex from NSF/α-SNAP-mediated disassembly and accelerates SNARE-dependent fusion kinetics in the presence of NSF and α-SNAP. The SLP in domain 3a is indispensable in Munc18c-assisted resistance to NSF and α-SNAP. Together, our findings demonstrate that Munc18c protects the prefusion SNARE complex from α-SNAP and NSF, promoting SNARE-dependent membrane fusion through its SLP.
Collapse
Affiliation(s)
- Furong Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Ruyue He
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Xinyu Xu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Min Zhu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China.
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China.
| |
Collapse
|
5
|
Xu B, Fan F, Liu Y, Liu Y, Zhou L, Yu H. Distinct Effects of Familial Parkinson's Disease-Associated Mutations on α-Synuclein Phase Separation and Amyloid Aggregation. Biomolecules 2023; 13:biom13050726. [PMID: 37238596 DOI: 10.3390/biom13050726] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 04/16/2023] [Accepted: 04/19/2023] [Indexed: 05/28/2023] Open
Abstract
The Lewy bodies and Lewy neurites are key pathological hallmarks of Parkinson's disease (PD). Single-point mutations associated with familial PD cause α-synuclein (α-Syn) aggregation, leading to the formation of Lewy bodies and Lewy neurites. Recent studies suggest α-Syn nucleates through liquid-liquid phase separation (LLPS) to form amyloid aggregates in a condensate pathway. How PD-associated mutations affect α-Syn LLPS and its correlation with amyloid aggregation remains incompletely understood. Here, we examined the effects of five mutations identified in PD, A30P, E46K, H50Q, A53T, and A53E, on the phase separation of α-Syn. All other α-Syn mutants behave LLPS similarly to wild-type (WT) α-Syn, except that the E46K mutation substantially promotes the formation of α-Syn condensates. The mutant α-Syn droplets fuse to WT α-Syn droplets and recruit α-Syn monomers into their droplets. Our studies showed that α-Syn A30P, E46K, H50Q, and A53T mutations accelerated the formation of amyloid aggregates in the condensates. In contrast, the α-Syn A53E mutant retarded the aggregation during the liquid-to-solid phase transition. Finally, we observed that WT and mutant α-Syn formed condensates in the cells, whereas the E46K mutation apparently promoted the formation of condensates. These findings reveal that familial PD-associated mutations have divergent effects on α-Syn LLPS and amyloid aggregation in the phase-separated condensates, providing new insights into the pathogenesis of PD-associated α-Syn mutations.
Collapse
Affiliation(s)
- Bingkuan Xu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Fengshuo Fan
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Yunpeng Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Lin Zhou
- School of Chemistry and Bioengineering, Nanjing Normal University Taizhou College, Taizhou 225300, China
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| |
Collapse
|
6
|
Zhu M, Xu H, Jiang Y, Yu H, Liu Y. Epigallocatechin gallate inhibits SNARE-dependent membrane fusion by blocking trans-SNARE assembly. FEBS Open Bio 2022; 12:2111-2121. [PMID: 36111501 PMCID: PMC9714361 DOI: 10.1002/2211-5463.13488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/06/2022] [Accepted: 09/15/2022] [Indexed: 01/25/2023] Open
Abstract
Insulin secretion is a signal-triggered process that requires membrane fusion between the secretory granules and plasma membrane in pancreatic β cells. The exocytosis of insulin is mediated by target-soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs) on the plasma membrane and vesicle-SNAREs on the vesicles, which assemble into a quaternary trans-SNARE complex to initiate the fusion. Expression of fusion proteins is reduced in the islets of patients with type II diabetes, indicating that SNARE-mediated fusion defect is closely related to insulin-based metabolic diseases. Previous studies have suggested that epigallocatechin gallate (EGCG) has an inhibitory effect on membrane fusion. In the present study, we performed in vitro reconstitution assays to unravel the molecular mechanisms of EGCG in SNARE-mediated insulin secretory vesicle fusion. Our data show that EGCG efficiently inhibits insulin secretory SNARE-mediated membrane fusion. Mechanistic studies indicated that EGCG blocks the formation of the trans-SNARE complex. Furthermore, calcium/synaptotagmin-7-stimulated fusion kinetics were largely reduced by EGCG, confirming that it is a potential regulator of SNARE-dependent insulin secretion. Our findings suggest that the trans-SNARE complex might be a promising target for controlling SNARE-dependent vesicle fusion.
Collapse
Affiliation(s)
- Min Zhu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life SciencesNanjing Normal UniversityChina
| | - Han Xu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life SciencesNanjing Normal UniversityChina
| | - Yuting Jiang
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life SciencesNanjing Normal UniversityChina
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life SciencesNanjing Normal UniversityChina
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life SciencesNanjing Normal UniversityChina
| |
Collapse
|
7
|
Liu F, He R, Zhu M, Zhou L, Liu Y, Yu H. Assembly-promoting protein Munc18c stimulates SNARE-dependent membrane fusion through its SNARE-like peptide. J Biol Chem 2022; 298:102470. [PMID: 36087838 PMCID: PMC9547204 DOI: 10.1016/j.jbc.2022.102470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 09/02/2022] [Accepted: 09/03/2022] [Indexed: 11/19/2022] Open
Abstract
Intracellular vesicle fusion requires the soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and their cognate Sec1/Munc18 (SM) proteins. How SM proteins act in concert with trans-SNARE complexes to promote membrane fusion remains incompletely understood. Munc18c, a broadly distributed SM protein, selectively regulates multiple exocytotic pathways, including GLUT4 exocytosis. Here, using an in vitro reconstituted system, we discovered a SNARE-like peptide (SLP), conserved in Munc18-1 of synaptic exocytosis, is crucial to the stimulatory activity of Munc18c in vesicle fusion. The direct stimulation of the SNARE-mediated fusion reaction by SLP further supported the essential role of this fragment. Interestingly, we found SLP strongly accelerates the membrane fusion rate when anchored to the target membrane but not the vesicle membrane, suggesting it primarily interacts with t-SNAREs in cis to drive fusion. Furthermore, we determined the SLP fragment is competitive with the full-length Munc18c protein and specific to the cognate v-SNARE isoforms, supporting how it could resemble Munc18c’s activity in membrane fusion. Together, our findings demonstrate that Munc18c facilitates SNARE-dependent membrane fusion through SLP, revealing that the t-SNARE-SLP binding mode might be a conserved mechanism for the stimulatory function of SM proteins in vesicle fusion.
Collapse
Affiliation(s)
- Furong Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Ruyue He
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Min Zhu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Lin Zhou
- School of Chemistry and Bioengineering, Nanjing Normal University Taizhou College, Taizhou, China
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China.
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China.
| |
Collapse
|
8
|
Xu B, Chen J, Liu Y. Curcumin Interacts with α-Synuclein Condensates To Inhibit Amyloid Aggregation under Phase Separation. ACS OMEGA 2022; 7:30281-30290. [PMID: 36061735 PMCID: PMC9434619 DOI: 10.1021/acsomega.2c03534] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 08/03/2022] [Indexed: 05/27/2023]
Abstract
The amyloid aggregation of α-synuclein (α-Syn) is highly associated with Parkinson's disease (PD). Discovering α-Syn amyloid inhibitors is one of the strategies for PD therapies. Recent studies suggested that α-Syn undergoes phase separation to accelerate amyloid aggregation. Molecules modulating α-Syn phase separation or transition have the potential to regulate amyloid aggregation. Here, we discovered that curcumin, a small natural molecule, interacts with α-Syn during phase separation. Our study showed that curcumin neither affects the formation of α-Syn condensates nor influences the initial morphology of α-Syn condensates. However, curcumin decreases the fluidity of α-Syn inside the condensates and efficiently inhibits α-Syn from turning into an amyloid. It also inhibits the amyloid aggregations of PD disease-related α-Syn E46K and H50Q mutants under phase separation. Furthermore, curcumin can destabilize preformed α-Syn amyloid aggregates in the condensates. Together, our findings demonstrate that curcumin regulates α-Syn amyloid formation during protein phase separation and reveal that α-Syn amyloid aggregation under phase separation can be modulated by small molecules.
Collapse
|
9
|
You X, Baiz CR. Importance of Hydrogen Bonding in Crowded Environments: A Physical Chemistry Perspective. J Phys Chem A 2022; 126:5881-5889. [PMID: 35968816 DOI: 10.1021/acs.jpca.2c03803] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cells are heterogeneous on every length and time scale; cytosol contains thousands of proteins, lipids, nucleic acids, and small molecules, and molecular interactions within this crowded environment determine the structure, dynamics, and stability of biomolecules. For decades, the effects of crowding at the atomistic scale have been overlooked in favor of more tractable models largely based on thermodynamics. Crowding can affect the conformations and stability of biomolecules by modulating water structure and dynamics within the cell, and these effects are nonlocal and environment dependent. Thus, characterizing water's hydrogen-bond (H-bond) networks is a critical step toward a complete microscopic crowding model. This perspective provides an overview of molecular crowding and describes recent time-resolved spectroscopy approaches investigating H-bond networks and dynamics in crowded or otherwise complex aqueous environments. Ultrafast spectroscopy combined with atomistic simulations has emerged as a powerful combination for studying H-bond structure and dynamics in heterogeneous multicomponent systems. We discuss the ongoing challenges toward developing a complete atomistic description of macromolecular crowding from an experimental as well as a theoretical perspective.
Collapse
Affiliation(s)
- Xiao You
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 19104, United States
| | - Carlos R Baiz
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 19104, United States
| |
Collapse
|
10
|
Xu B, Mo X, Chen J, Yu H, Liu Y. Myricetin Inhibits α-Synuclein Amyloid Aggregation by Delaying the Liquid-to-Solid Phase Transition. Chembiochem 2022; 23:e202200216. [PMID: 35657723 DOI: 10.1002/cbic.202200216] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 06/02/2022] [Indexed: 11/12/2022]
Abstract
The aggregation of α-synuclein (α-Syn) is a critical pathological hallmark of Parkinson's disease (PD). Prevention of α-Syn aggregation has become a key strategy for treating PD. Recent studies have suggested that α-Syn undergoes liquid-liquid phase separation (LLPS) to facilitate nucleation and amyloid formation. Here, we examined the modulation of α-Syn aggregation by myricetin, a polyhydroxyflavonol compound, under the conditions of LLPS. Unexpectedly, neither the initial morphology nor the phase-separated fraction of α-Syn was altered by myricetin. However, the dynamics of α-Syn condensates decreased upon myricetin binding. Further studies showed that myricetin dose-dependently inhibits amyloid aggregation in the condensates by delaying the liquid-to-solid phase transition. In addition, myricetin could disassemble the preformed α-Syn amyloid aggregates matured from the condensates. Together, our study shows that myricetin inhibits α-Syn amyloid aggregation in the condensates by retarding the liquid-to-solid phase transition and reveals that α-Syn phase transition can be targeted to inhibit amyloid aggregation.
Collapse
Affiliation(s)
- Bingkuan Xu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, No. 1 Wenyuan Road, Nanjing, 210046, (P. R. China)
| | - Xiaoli Mo
- Biology Department, Clark University 950 Main Street, Worcester, Massachusetts (USA) 01610
| | - Jing Chen
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, No. 1 Wenyuan Road, Nanjing, 210046, (P. R. China)
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, No. 1 Wenyuan Road, Nanjing, 210046, (P. R. China)
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, No. 1 Wenyuan Road, Nanjing, 210046, (P. R. China)
| |
Collapse
|
11
|
Circularized fluorescent nanodiscs for probing protein-lipid interactions. Commun Biol 2022; 5:507. [PMID: 35618817 PMCID: PMC9135701 DOI: 10.1038/s42003-022-03443-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 05/03/2022] [Indexed: 12/29/2022] Open
Abstract
Protein–lipid interactions are vital for numerous transmembrane signaling pathways. However, simple tools to characterize these interactions remain scarce and are much needed to advance our understanding of signal transduction across lipid bilayers. To tackle this challenge, we herein engineer nanodisc as a robust fluorescent sensor for reporting membrane biochemical reactions. We circularize nanodiscs via split GFP and thereby create an intensity-based fluorescent sensor (isenND) for detecting membrane binding and remodeling events. We show that isenND responds robustly and specifically to the action of a diverse array of membrane-interacting proteins and peptides, ranging from synaptotagmin and synuclein involved in neurotransmission to viral fusion peptides of HIV-1 and SARS-CoV-2. Together, isenND can serve as a versatile biochemical reagent useful for basic and translational research of membrane biology. A fluorescent probe for detecting membrane protein binding and remodeling events is presented, which relies on split-GFP technology to generate circularized nanodiscs useful in membrane protein biophysics and structural biology.
Collapse
|
12
|
Huang S, Mo X, Wang J, Ye X, Yu H, Liu Y. α-Synuclein phase separation and amyloid aggregation are modulated by C-terminal truncations. FEBS Lett 2022; 596:1388-1400. [PMID: 35485974 DOI: 10.1002/1873-3468.14361] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 04/10/2022] [Accepted: 04/16/2022] [Indexed: 11/11/2022]
Abstract
The aggregation of α-synuclein (α-Syn) is a key pathological hallmark of Parkinson's disease (PD). α-Syn undergoes liquid-liquid phase separation (LLPS) to drive amyloid aggregation. How the LLPS of α-Syn is regulated remains largely unknown. Here, we discovered that the C-terminal region modulates α-Syn phase separation through electrostatic interactions. The wild-type (WT) and PD disease-related truncated α-Syn can co-exist in the condensates. The truncated α-Syn could dramatically promote WT α-Syn phase separation. Further studies demonstrated that the truncated α-Syn accelerated WT α-Syn turning to amyloid aggregates by modulation of phase separation. Together, our findings disclose the role of the C-terminal domain in the LLPS of α-Syn and pave the path for understanding the mechanism of truncated α-Syn in PD pathology.
Collapse
Affiliation(s)
- Shuai Huang
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, China
| | - Xiaoli Mo
- Biology Department, Clark University, Worcester, Massachusetts, 01610, USA
| | - Jieyi Wang
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, China
| | - Xinyi Ye
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, China
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, China
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, China
| |
Collapse
|
13
|
Qian T, Li C, Liu F, Xu K, Wan C, Liu Y, Yu H. Arabidopsis synaptotagmin 1 mediates lipid transport in a lipid composition-dependent manner. Traffic 2022; 23:346-356. [PMID: 35451158 DOI: 10.1111/tra.12844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 04/11/2022] [Accepted: 04/15/2022] [Indexed: 11/29/2022]
Abstract
The endoplasmic reticulum (ER) - plasma membrane (PM) contact sites (EPCSs) are structurally conserved in eukaryotes. The Arabidopsis ER-anchored synaptotagmin 1 (SYT1), enriched in EPCSs, plays a critical role in plant abiotic stress tolerance. It has become clear that SYT1 interacts with PM to mediate ER-PM connectivity. However, whether SYT1 performs additional functions at EPCSs remains unknown. Here, we reported that SYT1 efficiently transfers phospholipids between membranes. The lipid transfer activity of SYT1 is highly dependent on PI(4,5)P2 , a signal lipid accumulated at the PM under abiotic stress. Mechanically, while SYT1 transfers lipids fundamentally through the synaptotagmin-like mitochondrial-lipid-binding protein (SMP) domain, the efficient lipid transport requires the C2A domain-mediated membrane tethering. Interestingly, we observed that Ca2+ could stimulate SYT1-mediated lipid transport. In addition to PI(4,5)P2 , the Ca2+ activation requires the phosphatidylserine, another negatively charged lipid on the opposed membrane. Together, our studies identified Arabidopsis SYT1 as a lipid transfer protein at EPCSs and demonstrated it takes conserved as well as divergent mechanisms with other extend-synaptotagmins. The critical role of lipid composition and Ca2+ reveals SYT1-mediated lipid transport is highly regulated by signals in response to abiotic stresses.
Collapse
Affiliation(s)
- Tiantian Qian
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Chenlu Li
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Furong Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Kai Xu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Chun Wan
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| |
Collapse
|
14
|
Wang S, Ma C. Neuronal SNARE complex assembly guided by Munc18-1 and Munc13-1. FEBS Open Bio 2022; 12:1939-1957. [PMID: 35278279 PMCID: PMC9623535 DOI: 10.1002/2211-5463.13394] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 02/28/2022] [Accepted: 03/10/2022] [Indexed: 01/25/2023] Open
Abstract
Neurotransmitter release by Ca2+ -triggered synaptic vesicle exocytosis is essential for information transmission in the nervous system. The soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs) syntaxin-1, SNAP-25, and synaptobrevin-2 form the SNARE complex to bring synaptic vesicles and the plasma membranes together and to catalyze membrane fusion. Munc18-1 and Munc13-1 regulate synaptic vesicle priming via orchestrating neuronal SNARE complex assembly. In this review, we summarize recent advances toward the functions and molecular mechanisms of Munc18-1 and Munc13-1 in guiding neuronal SNARE complex assembly, and discuss the functional similarities and differences between Munc18-1 and Munc13-1 in neurons and their homologs in other intracellular membrane trafficking systems.
Collapse
Affiliation(s)
- Shen Wang
- Key Laboratory of Molecular Biophysics of the Ministry of EducationCollege of Life Science and TechnologyHuazhong University of Science and TechnologyWuhanChina
| | - Cong Ma
- Key Laboratory of Molecular Biophysics of the Ministry of EducationCollege of Life Science and TechnologyHuazhong University of Science and TechnologyWuhanChina
| |
Collapse
|
15
|
Huang S, Xu B, Liu Y. Calcium promotes α-synuclein liquid-liquid phase separation to accelerate amyloid aggregation. Biochem Biophys Res Commun 2022; 603:13-20. [PMID: 35276458 DOI: 10.1016/j.bbrc.2022.02.097] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 02/23/2022] [Indexed: 12/26/2022]
Abstract
α-Synuclein (α-Syn) is an aggregation-prone protein whose accumulation in Lewy bodies leads to neurodegenerative diseases like Parkinson's disease (PD). Calcium plays a critical role in neurons, and calcium dysregulation is one of the risk factors of PD. It is known that Ca2+ interacts with α-Syn and affects its assembly. However, how Ca2+ regulates α-Syn aggregation remains unclear. Here, we reported that Ca2+ accelerates α-Syn amyloid aggregation through the modulation of protein phase separation. We observed that Ca2+ promotes the formation of α-Syn liquid droplets but does not change the protein fluidity inside the droplets. Further studies showed Ca2+-involved α-Syn droplets are still able to fuse. A metal chelator eliminated Ca2+-induced enlargement of α-Syn droplets, suggesting the influence of Ca2+ on α-Syn assembly could be reversed at the stage of liquid-liquid phase separation (LLPS). Interestingly, our data showed Ca2+ still promoted α-Syn phase separation in the presence of the lipid membranes. In addition, Ca2+/α-syn droplets could efficiently recruit lipid vesicles to the surface of these condensates. Our findings demonstrate that Ca2+ facilitates α-Syn phase separation to accelerate amyloid aggregation and pave the path for understanding the implications of Ca2+ in α-Syn accumulation and PD.
Collapse
Affiliation(s)
- Shuai Huang
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, China
| | - Bingkuan Xu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, China
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, China.
| |
Collapse
|
16
|
Manganese promotes α-synuclein amyloid aggregation through the induction of protein phase transition. J Biol Chem 2021; 298:101469. [PMID: 34871547 PMCID: PMC8717548 DOI: 10.1016/j.jbc.2021.101469] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 11/24/2021] [Accepted: 11/25/2021] [Indexed: 01/31/2023] Open
Abstract
α-Synuclein (α-Syn) is the major protein component of Lewy bodies, a key pathological feature of Parkinson’s disease (PD). The manganese ion Mn2+ has been identified as an environmental risk factor of PD. However, it remains unclear how Mn2+ regulates α-Syn aggregation. Here, we discovered that Mn2+accelerates α-Syn amyloid aggregation through the regulation of protein phase separation. We found that Mn2+ not only promotes α-Syn liquid-to-solid phase transition but also directly induces soluble α-Syn monomers to form solid-like condensates. Interestingly, the lipid membrane is integrated into condensates during Mn2+-induced α-Syn phase transition; however, the preformed Mn2+/α-syn condensates can only recruit lipids to the surface of condensates. In addition, this phase transition can largely facilitate α-Syn amyloid aggregation. Although the Mn2+-induced condensates do not fuse, our results demonstrated that they could recruit soluble α-Syn monomers into the existing condensates. Furthermore, we observed that a manganese chelator reverses Mn2+-induced α-Syn aggregation during the phase transition stage. However, after maturation, α-Syn aggregation becomes irreversible. These findings demonstrate that Mn2+ facilitates α-Syn phase transition to accelerate the formation of α-Syn aggregates and provide new insights for targeting α-Syn phase separation in PD treatment.
Collapse
|
17
|
Le Saux S, Aubert-Pouëssel A, Mohamed KE, Martineau P, Guglielmi L, Devoisselle JM, Legrand P, Chopineau J, Morille M. Interest of extracellular vesicles in regards to lipid nanoparticle based systems for intracellular protein delivery. Adv Drug Deliv Rev 2021; 176:113837. [PMID: 34144089 DOI: 10.1016/j.addr.2021.113837] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 06/04/2021] [Accepted: 06/12/2021] [Indexed: 12/14/2022]
Abstract
Compared to chemicals that continue to dominate the overall pharmaceutical market, protein therapeutics offer the advantages of higher specificity, greater activity, and reduced toxicity. While nearly all existing therapeutic proteins were developed against soluble or extracellular targets, the ability for proteins to enter cells and target intracellular compartments can significantly broaden their utility for a myriad of exiting targets. Given their physical, chemical, biological instability that could induce adverse effects, and their limited ability to cross cell membranes, delivery systems are required to fully reveal their biological potential. In this context, as natural protein nanocarriers, extracellular vesicles (EVs) hold great promise. Nevertheless, if not present naturally, bringing an interest protein into EV is not an easy task. In this review, we will explore methods used to load extrinsic protein into EVs and compare these natural vectors to their close synthetic counterparts, liposomes/lipid nanoparticles, to induce intracellular protein delivery.
Collapse
|
18
|
Qian T, Li C, He R, Wan C, Liu Y, Yu H. Calcium-dependent and -independent lipid transfer mediated by tricalbins in yeast. J Biol Chem 2021; 296:100729. [PMID: 33933446 PMCID: PMC8163979 DOI: 10.1016/j.jbc.2021.100729] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 04/23/2021] [Accepted: 04/28/2021] [Indexed: 11/12/2022] Open
Abstract
Membrane contact sites (MCSs) formed between the endoplasmic reticulum (ER) and the plasma membrane (PM) provide a platform for nonvesicular lipid exchange. The ER-anchored tricalbins (Tcb1, Tcb2, and Tcb3) are critical tethering factors at ER–PM MCSs in yeast. Tricalbins possess a synaptotagmin-like mitochondrial-lipid-binding protein (SMP) domain and multiple Ca2+-binding C2 domains. Although tricalbins have been suggested to be involved in lipid exchange at the ER–PM MCSs, it remains unclear whether they directly mediate lipid transport. Here, using in vitro lipid transfer assays, we discovered that tricalbins are capable of transferring phospholipids between membranes. Unexpectedly, while its lipid transfer activity was markedly elevated by Ca2+, Tcb3 constitutively transferred lipids even in the absence of Ca2+. The stimulatory activity of Ca2+ on Tcb3 required intact Ca2+-binding sites on both the C2C and C2D domains of Tcb3, while Ca2+-independent lipid transport was mediated by the SMP domain that transferred lipids via direct interactions with phosphatidylserine and other negatively charged lipid molecules. These findings establish tricalbins as lipid transfer proteins, and reveal Ca2+-dependent and -independent lipid transfer activities mediated by these tricalbins, providing new insights into their mechanism in maintaining PM integrity at ER–PM MCSs.
Collapse
Affiliation(s)
- Tiantian Qian
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Chenlu Li
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Ruyue He
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Chun Wan
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, USA
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China.
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China.
| |
Collapse
|
19
|
Liu Y, Wan C, Rathore SS, Stowell MHB, Yu H, Shen J. SNARE Zippering Is Suppressed by a Conformational Constraint that Is Removed by v-SNARE Splitting. Cell Rep 2021; 34:108611. [PMID: 33440145 PMCID: PMC7837384 DOI: 10.1016/j.celrep.2020.108611] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/18/2020] [Accepted: 12/16/2020] [Indexed: 12/05/2022] Open
Abstract
Intracellular vesicle fusion is catalyzed by soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs). Vesicle-anchored v-SNAREs pair with target membrane-associated t-SNAREs to form trans-SNARE complexes, releasing free energy to drive membrane fusion. However, trans-SNARE complexes are unable to assemble efficiently unless activated by Sec1/Munc18 (SM) proteins. Here, we demonstrate that SNAREs become fully active when the v-SNARE is split into two fragments, eliminating the requirement of SM protein activation. Mechanistically, v-SNARE splitting accelerates the zippering of trans-SNARE complexes, mimicking the stimulatory function of SM proteins. Thus, SNAREs possess the full potential to drive efficient membrane fusion but are suppressed by a conformational constraint. This constraint is removed by SM protein activation or v-SNARE splitting. We suggest that ancestral SNAREs originally evolved to be fully active in the absence of SM proteins. Later, a conformational constraint coevolved with SM proteins to achieve the vesicle fusion specificity demanded by complex endomembrane systems. SNAREs are unable to drive efficient membrane fusion unless activated by Sec1/Munc18 (SM) proteins. In this work, Liu et al. demonstrate that v-SNARE splitting mimics SM protein activation and unleashes the full membrane fusion potential of SNAREs.
Collapse
Affiliation(s)
- Yinghui Liu
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA; Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Chun Wan
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Shailendra S Rathore
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Michael H B Stowell
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Haijia Yu
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA; Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
| | - Jingshi Shen
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA.
| |
Collapse
|
20
|
Zhang X, Xu Q, Zi Z, Liu Z, Wan C, Crisman L, Shen J, Liu X. Programmable Extracellular Vesicles for Macromolecule Delivery and Genome Modifications. Dev Cell 2020; 55:784-801.e9. [PMID: 33296682 DOI: 10.1016/j.devcel.2020.11.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 05/13/2020] [Accepted: 11/04/2020] [Indexed: 12/19/2022]
Abstract
Getting large macromolecules through the plasma membrane and endosomal barriers remains a major challenge. Here, we report a generalizable method of delivering proteins and ribonucleoproteins (RNPs) to cells in vitro and mouse liver tissue in vivo with engineered ectosomes. These ectosomes, referred to as "Gectosomes," are designed to co-encapsulate vesicular stomatitis virus G protein (VSV-G) with bioactive macromolecules via split GFP complementation. We found that this method enables active cargo loading, improves the specific activity of cargo delivery, and facilitates Gectosome purification. Experimental and mathematical modeling analyses suggest that active cargo loading reduces non-specific encapsulation of cellular proteins, particularly nucleic-acid-binding proteins. Using Gectosomes that encapsulate Cre, Ago2, and SaCas9, we demonstrate their ability to execute designed modifications of endogenous genes in cell lines in vitro and mouse liver tissue in vivo, paving the way toward applications of this technology for the treatment of a wide range of human diseases.
Collapse
Affiliation(s)
- Xiaojuan Zhang
- Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA
| | - Quanbin Xu
- Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA
| | - Zhike Zi
- Max Planck Institute for Molecular Genetics, Otto Warburg Laboratory, 14195 Berlin, Germany; German Federal Institute for Risk Assessment, Department of Experimental Toxicology and ZEBET, 10589 Berlin, Germany
| | - Zeyu Liu
- Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA
| | - Chun Wan
- Department of MCD-Biology, University of Colorado, Boulder, CO 80309, USA
| | - Lauren Crisman
- Department of MCD-Biology, University of Colorado, Boulder, CO 80309, USA
| | - Jingshi Shen
- Department of MCD-Biology, University of Colorado, Boulder, CO 80309, USA
| | - Xuedong Liu
- Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA.
| |
Collapse
|
21
|
Rathore SS, Liu Y, Yu H, Wan C, Lee M, Yin Q, Stowell MHB, Shen J. Intracellular Vesicle Fusion Requires a Membrane-Destabilizing Peptide Located at the Juxtamembrane Region of the v-SNARE. Cell Rep 2019; 29:4583-4592.e3. [PMID: 31875562 PMCID: PMC6990648 DOI: 10.1016/j.celrep.2019.11.107] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 10/13/2019] [Accepted: 11/26/2019] [Indexed: 12/11/2022] Open
Abstract
Intracellular vesicle fusion is mediated by soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs) and Sec1/Munc18 (SM) proteins. It is generally accepted that membrane fusion occurs when the vesicle and target membranes are brought into close proximity by SNAREs and SM proteins. In this work, we demonstrate that, for fusion to occur, membrane bilayers must be destabilized by a conserved membrane-embedded motif located at the juxtamembrane region of the vesicle-anchored v-SNARE. Comprised of basic and hydrophobic residues, the juxtamembrane motif perturbs the lipid bilayer structure and promotes SNARE-SM-mediated membrane fusion. The juxtamembrane motif can be functionally substituted with an unrelated membrane-disrupting peptide in the membrane fusion reaction. These findings establish the juxtamembrane motif of the v-SNARE as a membrane-destabilizing peptide. Requirement of membrane-destabilizing peptides is likely a common feature of biological membrane fusion.
Collapse
Affiliation(s)
- Shailendra S Rathore
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, 347 UCB, Boulder, CO 80309, USA
| | - Yinghui Liu
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, 347 UCB, Boulder, CO 80309, USA; Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Haijia Yu
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, 347 UCB, Boulder, CO 80309, USA; Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
| | - Chun Wan
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, 347 UCB, Boulder, CO 80309, USA
| | - MyeongSeon Lee
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, 347 UCB, Boulder, CO 80309, USA
| | - Qian Yin
- Department of Biological Sciences and Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Michael H B Stowell
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, 347 UCB, Boulder, CO 80309, USA
| | - Jingshi Shen
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, 347 UCB, Boulder, CO 80309, USA.
| |
Collapse
|
22
|
Sec17 (α-SNAP) and Sec18 (NSF) restrict membrane fusion to R-SNAREs, Q-SNAREs, and SM proteins from identical compartments. Proc Natl Acad Sci U S A 2019; 116:23573-23581. [PMID: 31685636 DOI: 10.1073/pnas.1913985116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Membrane fusion at each organelle requires conserved proteins: Rab-GTPases, effector tethering complexes, Sec1/Munc18 (SM)-family SNARE chaperones, SNAREs of the R, Qa, Qb, and Qc families, and the Sec17/α-SNAP and ATP-dependent Sec18/NSF SNARE chaperone system. The basis of organelle-specific fusion, which is essential for accurate protein compartmentation, has been elusive. Rab family GTPases, SM proteins, and R- and Q-SNAREs may contribute to this specificity. We now report that the fusion supported by SNAREs alone is both inefficient and promiscuous with respect to organelle identity and to stimulation by SM family proteins or complexes. SNARE-only fusion is abolished by the disassembly chaperones Sec17 and Sec18. Efficient fusion in the presence of Sec17 and Sec18 requires a tripartite match between the organellar identities of the R-SNARE, the Q-SNAREs, and the SM protein or complex. The functions of Sec17 and Sec18 are not simply negative regulation; they stimulate fusion with either vacuolar SNAREs and their SM protein complex HOPS or endoplasmic reticulum/cis-Golgi SNAREs and their SM protein Sly1. The fusion complex of each organelle is assembled from its own functionally matching pieces to engage Sec17/Sec18 for fusion stimulation rather than inhibition.
Collapse
|
23
|
Courtney NA, Bao H, Briguglio JS, Chapman ER. Synaptotagmin 1 clamps synaptic vesicle fusion in mammalian neurons independent of complexin. Nat Commun 2019; 10:4076. [PMID: 31501440 PMCID: PMC6733930 DOI: 10.1038/s41467-019-12015-w] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 08/12/2019] [Indexed: 02/01/2023] Open
Abstract
Synaptic vesicle (SV) exocytosis is mediated by SNARE proteins. Reconstituted SNAREs are constitutively active, so a major focus has been to identify fusion clamps that regulate their activity in synapses: the primary candidates are synaptotagmin (syt) 1 and complexin I/II. Syt1 is a Ca2+ sensor for SV release that binds Ca2+ via tandem C2-domains, C2A and C2B. Here, we first determined whether these C2-domains execute distinct functions. Remarkably, the C2B domain profoundly clamped all forms of SV fusion, despite synchronizing residual evoked release and rescuing the readily-releasable pool. Release was strongly enhanced by an adjacent C2A domain, and by the concurrent binding of complexin to trans-SNARE complexes. Knockdown of complexin had no impact on C2B-mediated clamping of fusion. We postulate that the C2B domain of syt1, independent of complexin, is the molecular clamp that arrests SVs prior to Ca2+-triggered fusion.
Collapse
Affiliation(s)
- Nicholas A Courtney
- Department of Neuroscience and Howard Hughes Medical Institute, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Huan Bao
- Department of Neuroscience and Howard Hughes Medical Institute, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Joseph S Briguglio
- Department of Neuroscience and Howard Hughes Medical Institute, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Edwin R Chapman
- Department of Neuroscience and Howard Hughes Medical Institute, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA.
| |
Collapse
|
24
|
Gulbranson DR, Crisman L, Lee M, Ouyang Y, Menasche BL, Demmitt BA, Wan C, Nomura T, Ye Y, Yu H, Shen J. AAGAB Controls AP2 Adaptor Assembly in Clathrin-Mediated Endocytosis. Dev Cell 2019; 50:436-446.e5. [PMID: 31353312 DOI: 10.1016/j.devcel.2019.06.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 04/29/2019] [Accepted: 06/20/2019] [Indexed: 12/26/2022]
Abstract
Multimeric adaptors are broadly involved in vesicle-mediated membrane trafficking. AP2 adaptor, in particular, plays a central role in clathrin-mediated endocytosis (CME) by recruiting cargo and clathrin to endocytic sites. It is generally thought that trafficking adaptors such as AP2 adaptor assemble spontaneously. In this work, however, we discovered that AP2 adaptor assembly is an ordered process controlled by alpha and gamma adaptin binding protein (AAGAB), an uncharacterized factor identified in our genome-wide genetic screen of CME. AAGAB guides the sequential association of AP2 subunits and stabilizes assembly intermediates. Without the assistance of AAGAB, AP2 subunits fail to form the adaptor complex, leading to their degradation. The function of AAGAB is abrogated by a mutation that causes punctate palmoplantar keratoderma type 1 (PPKP1), a human skin disease. Since other multimeric trafficking adaptors operate in an analogous manner to AP2 adaptor, their assembly likely involves a similar regulatory mechanism.
Collapse
Affiliation(s)
- Daniel R Gulbranson
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Lauren Crisman
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - MyeongSeon Lee
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Yan Ouyang
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Bridget L Menasche
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Brittany A Demmitt
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA; Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80309, USA
| | - Chun Wan
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Toshifumi Nomura
- Department of Dermatology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Yihong Ye
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Haijia Yu
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA; Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
| | - Jingshi Shen
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA.
| |
Collapse
|
25
|
Jiang X, Zhang Z, Cheng K, Wu Q, Jiang L, Pielak GJ, Liu M, Li C. Membrane-mediated disorder-to-order transition of SNAP25 flexible linker facilitates its interaction with syntaxin-1 and SNARE-complex assembly. FASEB J 2019; 33:7985-7994. [PMID: 30916996 DOI: 10.1096/fj.201802796r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex comprises synaptosome-associated protein of 25 kDa (SNAP25), syntaxin-1a (syx-1), and synaptobrevin 2, which is essential for many physiologic processes requiring membrane fusion. Several studies imply that the loop region of SNAP25 plays important roles in SNARE-complex assembly. However, why and how the flexible loop facilitates the complex assembly remains poorly understood because it is purposely deleted in almost all structural studies. By using NMR spectroscopy and circular dichroism spectropolarimetry, we characterized SNAP25 structure and interactions with other SNAREs in aqueous buffer and in the membrane. We found that the N-terminal of the SNAP25 loop region binds with membrane, and this interaction induced a disorder-to-order conformational change of the loop, resulting in enhanced interaction between the C-terminal of the SNAP25 loop and syx-1. We further proved that SNARE-complex assembly efficiency decreased when we disrupted the electrostatic interaction between C-terminal of the SNAP25 loop and syx-1, suggesting that the SNAP25 loop region facilitates SNARE-complex assembly through promoting prefusion SNARE binary complex formation. Our work elucidates the role of the flexible loop and the membrane environment in SNARE-complex assembly at the residue level, which helps to understand membrane fusion, a fundamental transport and communication process in cells.-Jiang, X., Zhang, Z., Cheng, K., Wu, Q., Jiang, L., Pielak, G. J., Liu, M., Li, C. Membrane-mediated disorder-to-order transition of SNAP25 flexible linker facilitates its interaction with syntaxin-1 and SNARE-complex assembly.
Collapse
Affiliation(s)
- Xin Jiang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China.,Graduate University of Chinese Academy of Sciences, Beijing, China
| | - Zeting Zhang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
| | - Kai Cheng
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
| | - Qiong Wu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
| | - Ling Jiang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China.,Graduate University of Chinese Academy of Sciences, Beijing, China
| | - Gary J Pielak
- Department of Chemistry and Department of Biochemistry and Biophysics, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina, USA.,Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina, USA.,Integrative Program for Biological and Genome Sciences, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina, USA
| | - Maili Liu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China.,Graduate University of Chinese Academy of Sciences, Beijing, China
| | - Conggang Li
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China.,Graduate University of Chinese Academy of Sciences, Beijing, China
| |
Collapse
|
26
|
Yu H, Crisman L, Stowell MHB, Shen J. Functional Reconstitution of Intracellular Vesicle Fusion Using Purified SNAREs and Sec1/Munc18 (SM) Proteins. Methods Mol Biol 2019; 1860:237-249. [PMID: 30317509 DOI: 10.1007/978-1-4939-8760-3_15] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The fusion of intracellular vesicles with target membranes is mediated by two classes of conserved molecules-soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAP receptors or SNAREs) and Sec1/Munc18 (SM) proteins. A conserved function of SM proteins is to recognize their cognate trans-SNARE complexes and accelerate fusion kinetics. Here, we describe a physiologically relevant reconstitution system in which macromolecular crowding agents are included to recapitulate the crowded intracellular environment. Through this system, we elucidate the molecular mechanisms by which SNAREs and SM proteins drive vesicle fusion.
Collapse
Affiliation(s)
- Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China. .,Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, USA.
| | - Lauren Crisman
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Michael H B Stowell
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Jingshi Shen
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, USA.
| |
Collapse
|
27
|
Shen C, Liu Y, Yu H, Gulbranson DR, Kogut I, Bilousova G, Zhang C, Stowell MHB, Shen J. The N-peptide-binding mode is critical to Munc18-1 function in synaptic exocytosis. J Biol Chem 2018; 293:18309-18317. [PMID: 30275014 DOI: 10.1074/jbc.ra118.005254] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 09/25/2018] [Indexed: 01/09/2023] Open
Abstract
Sec1/Munc18 (SM) proteins promote intracellular vesicle fusion by binding to N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs). A key SNARE-binding mode of SM proteins involves the N-terminal peptide (N-peptide) motif of syntaxin, a SNARE subunit localized to the target membrane. In in vitro membrane fusion assays, inhibition of N-peptide motif binding previously has been shown to abrogate the stimulatory function of Munc18-1, a SM protein involved in synaptic exocytosis in neurons. The physiological role of the N-peptide-binding mode, however, remains unclear. In this work, we addressed this key question using a "clogged" Munc18-1 protein, in which an ectopic copy of the syntaxin N-peptide motif was directly fused to Munc18-1. We found that the ectopic N-peptide motif blocks the N-peptide-binding pocket of Munc18-1, preventing the latter from binding to the native N-peptide motif on syntaxin-1. In a reconstituted system, we observed that clogged Munc18-1 is defective in promoting SNARE zippering. When introduced into induced neuronal cells (iN cells) derived from human pluripotent stem cells, clogged Munc18-1 failed to mediate synaptic exocytosis. As a result, both spontaneous and evoked synaptic transmission was abolished. These genetic findings provide direct evidence for the crucial role of the N-peptide-binding mode of Munc18-1 in synaptic exocytosis. We suggest that clogged SM proteins will also be instrumental in defining the physiological roles of the N-peptide-binding mode in other vesicle-fusion pathways.
Collapse
Affiliation(s)
- Chong Shen
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
| | - Yinghui Liu
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309,; the Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Haijia Yu
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309,; the Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China,.
| | - Daniel R Gulbranson
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
| | - Igor Kogut
- the Department of Dermatology and Charles C. Gates Center for Regenerative Medicine, University of Colorado School of Medicine, Aurora, Colorado 80045, and
| | - Ganna Bilousova
- the Department of Dermatology and Charles C. Gates Center for Regenerative Medicine, University of Colorado School of Medicine, Aurora, Colorado 80045, and
| | - Chen Zhang
- the School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China
| | - Michael H B Stowell
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
| | - Jingshi Shen
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309,.
| |
Collapse
|
28
|
SNARE zippering requires activation by SNARE-like peptides in Sec1/Munc18 proteins. Proc Natl Acad Sci U S A 2018; 115:E8421-E8429. [PMID: 30127032 DOI: 10.1073/pnas.1802645115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) catalyze membrane fusion by forming coiled-coil bundles between membrane bilayers. The SNARE bundle zippers progressively toward the membranes, pulling the lipid bilayers into close proximity to fuse. In this work, we found that the +1 and +2 layers in the C-terminal domains (CTDs) of SNAREs are dispensable for reconstituted SNARE-mediated fusion reactions. By contrast, all CTD layers are required for fusion reactions activated by the cognate Sec1/Munc18 (SM) protein or a synthetic Vc peptide derived from the vesicular (v-) SNARE, correlating with strong acceleration of fusion kinetics. These results suggest a similar mechanism underlying the stimulatory functions of SM proteins and Vc peptide in SNARE-dependent membrane fusion. Unexpectedly, we identified a conserved SNARE-like peptide (SLP) in SM proteins that structurally and functionally resembles Vc peptide. Like Vc peptide, SLP binds and activates target (t-) SNAREs, accelerating the fusion reaction. Disruption of the t-SNARE-SLP interaction inhibits exocytosis in vivo. Our findings demonstrated that a t-SNARE-SLP intermediate must form before SNAREs can drive efficient vesicle fusion.
Collapse
|
29
|
Abstract
Up to 40% of intracellular water is confined due to the dense packing of macromolecules, ions, and osmolytes. Despite the large body of work concerning the effect of additives on the biomolecular structure and stability, the role of crowding and heterogeneity in these interactions is not well understood. Here, infrared spectroscopy and molecular dynamics simulations are used to describe the mechanisms by which crowding modulates hydrogen bonding interactions between water and dimethyl sulfoxide (DMSO). Specifically, we use formamide and dimethylformamide (DMF) as molecular crowders and show that the S═O hydrogen bond populations in aqueous mixtures are increased by both amides. These additives increase the amount of water within the DMSO first solvation shell through two mechanisms: (a) directly stabilizing water-DMSO hydrogen bonds; (b) increasing water exposure by destabilizing DMSO-DMSO self-interactions. Further, we quantified the hydrogen bond enthalpies between the different components: DMSO-water (61 kJ/mol) > DMSO-formamide (32 kJ/mol) > water-water (23 kJ/mol) ≫ formamide-water (4.7 kJ/mol). Spectra of carbonyl stretching vibrations show that DMSO induces the dehydration of amides as a result of strong DMSO-water interactions, which has been suggested as the main mechanism of protein destabilization.
Collapse
Affiliation(s)
- Kwang-Im Oh
- Department of Chemistry , University of Texas at Austin , 105 E 24th St. Stop A5300 , Austin , TX 78712 , United States
| | - Carlos R Baiz
- Department of Chemistry , University of Texas at Austin , 105 E 24th St. Stop A5300 , Austin , TX 78712 , United States
| |
Collapse
|
30
|
D'Agostino M, Risselada HJ, Lürick A, Ungermann C, Mayer A. A tethering complex drives the terminal stage of SNARE-dependent membrane fusion. Nature 2017; 551:634-638. [PMID: 29088698 DOI: 10.1038/nature24469] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 10/03/2017] [Indexed: 11/09/2022]
Abstract
Membrane fusion in eukaryotic cells mediates the biogenesis of organelles, vesicular traffic between them, and exo- and endocytosis of important signalling molecules, such as hormones and neurotransmitters. Distinct tasks in intracellular membrane fusion have been assigned to conserved protein systems. Tethering proteins mediate the initial recognition and attachment of membranes, whereas SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) protein complexes are considered as the core fusion engine. SNARE complexes provide mechanical energy to distort membranes and drive them through a hemifusion intermediate towards the formation of a fusion pore. This last step is highly energy-demanding. Here we combine the in vivo and in vitro fusion of yeast vacuoles with molecular simulations to show that tethering proteins are critical for overcoming the final energy barrier to fusion pore formation. SNAREs alone drive vacuoles only into the hemifused state. Tethering proteins greatly increase the volume of SNARE complexes and deform the site of hemifusion, which lowers the energy barrier for pore opening and provides the driving force. Thereby, tethering proteins assume a crucial mechanical role in the terminal stage of membrane fusion that is likely to be conserved at multiple steps of vesicular traffic. We therefore propose that SNAREs and tethering proteins should be considered as a single, non-dissociable device that drives fusion. The core fusion machinery may then be larger and more complex than previously thought.
Collapse
Affiliation(s)
- Massimo D'Agostino
- Département de Biochimie, Université de Lausanne, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
| | - Herre Jelger Risselada
- Georg-August University, Department of Theoretical Physics, Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany.,Leibniz Institute of Surface Modification, Chemical Department, Permoserstrasse 15, D-04318, Leipzig, Germany
| | - Anna Lürick
- University of Osnabrück, Department of Biology/Chemistry, Barbarastrasse 13, D-49076 Osnabrück, Germany
| | - Christian Ungermann
- University of Osnabrück, Department of Biology/Chemistry, Barbarastrasse 13, D-49076 Osnabrück, Germany
| | - Andreas Mayer
- Département de Biochimie, Université de Lausanne, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
| |
Collapse
|
31
|
Schwartz ML, Nickerson DP, Lobingier BT, Plemel RL, Duan M, Angers CG, Zick M, Merz AJ. Sec17 (α-SNAP) and an SM-tethering complex regulate the outcome of SNARE zippering in vitro and in vivo. eLife 2017; 6:27396. [PMID: 28925353 PMCID: PMC5643095 DOI: 10.7554/elife.27396] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 09/15/2017] [Indexed: 02/02/2023] Open
Abstract
Zippering of SNARE complexes spanning docked membranes is essential for most intracellular fusion events. Here, we explore how SNARE regulators operate on discrete zippering states. The formation of a metastable trans-complex, catalyzed by HOPS and its SM subunit Vps33, is followed by subsequent zippering transitions that increase the probability of fusion. Operating independently of Sec18 (NSF) catalysis, Sec17 (α-SNAP) either inhibits or stimulates SNARE-mediated fusion. If HOPS or Vps33 are absent, Sec17 inhibits fusion at an early stage. Thus, Vps33/HOPS promotes productive SNARE assembly in the presence of otherwise inhibitory Sec17. Once SNAREs are partially zipped, Sec17 promotes fusion in either the presence or absence of HOPS, but with faster kinetics when HOPS is absent, suggesting that ejection of the SM is a rate-limiting step.
Collapse
Affiliation(s)
- Matthew L Schwartz
- Department of Biochemistry, University of Washington School of Medicine, Seattle, United States
| | - Daniel P Nickerson
- Department of Biology, California State University, San Bernardino, United States
| | - Braden T Lobingier
- Department of Biochemistry, University of Washington School of Medicine, Seattle, United States
| | - Rachael L Plemel
- Department of Biochemistry, University of Washington School of Medicine, Seattle, United States
| | - Mengtong Duan
- Department of Biochemistry, University of Washington School of Medicine, Seattle, United States
| | - Cortney G Angers
- Department of Biochemistry, University of Washington School of Medicine, Seattle, United States
| | - Michael Zick
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, United States
| | - Alexey J Merz
- Department of Biochemistry, University of Washington School of Medicine, Seattle, United States.,Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, United States
| |
Collapse
|
32
|
Zhang Y. Energetics, kinetics, and pathway of SNARE folding and assembly revealed by optical tweezers. Protein Sci 2017; 26:1252-1265. [PMID: 28097727 PMCID: PMC5477538 DOI: 10.1002/pro.3116] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/03/2017] [Indexed: 01/17/2023]
Abstract
Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are universal molecular engines that drive membrane fusion. Particularly, synaptic SNAREs mediate fast calcium-triggered fusion of neurotransmitter-containing vesicles with plasma membranes for synaptic transmission, the basis of all thought and action. During membrane fusion, complementary SNAREs located on two apposed membranes (often called t- and v-SNAREs) join together to assemble into a parallel four-helix bundle, releasing the energy to overcome the energy barrier for fusion. A long-standing hypothesis suggests that SNAREs act like a zipper to draw the two membranes into proximity and thereby force them to fuse. However, a quantitative test of this SNARE zippering hypothesis was hindered by difficulties to determine the energetics and kinetics of SNARE assembly and to identify the relevant folding intermediates. Here, we first review different approaches that have been applied to study SNARE assembly and then focus on high-resolution optical tweezers. We summarize the folding energies, kinetics, and pathways of both wild-type and mutant SNARE complexes derived from this new approach. These results show that synaptic SNAREs assemble in four distinct stages with different functions: slow N-terminal domain association initiates SNARE assembly; a middle domain suspends and controls SNARE assembly; and rapid sequential zippering of the C-terminal domain and the linker domain directly drive membrane fusion. In addition, the kinetics and pathway of the stagewise assembly are shared by other SNARE complexes. These measurements prove the SNARE zippering hypothesis and suggest new mechanisms for SNARE assembly regulated by other proteins.
Collapse
Affiliation(s)
- Yongli Zhang
- Department of Cell Biology, Yale School of MedicineYale UniversityNew HavenConnecticut06511
| |
Collapse
|
33
|
Klink VP, Sharma K, Pant SR, McNeece B, Niraula P, Lawrence GW. Components of the SNARE-containing regulon are co-regulated in root cells undergoing defense. PLANT SIGNALING & BEHAVIOR 2017; 12:e1274481. [PMID: 28010187 PMCID: PMC5351740 DOI: 10.1080/15592324.2016.1274481] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 12/14/2016] [Accepted: 12/15/2016] [Indexed: 05/23/2023]
Abstract
The term regulon has been coined in the genetic model plant Arabidopsis thaliana, denoting a structural and physiological defense apparatus defined genetically through the identification of the penetration (pen) mutants. The regulon is composed partially by the soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor (SNARE) syntaxin PEN1. PEN1 has homology to a Saccharomyces cerevisae gene that regulates a Secretion (Sec) protein, Suppressor of Sec 1 (Sso1p). The regulon is also composed of the β-glucosidase (PEN2) and an ATP binding cassette (ABC) transporter (PEN3). While important in inhibiting pathogen infection, limited observations have been made regarding the transcriptional regulation of regulon genes until now. Experiments made using the model agricultural Glycine max (soybean) have identified co-regulated gene expression of regulon components. The results explain the observation of hundreds of genes expressed specifically in the root cells undergoing the natural process of defense. Data regarding additional G. max genes functioning within the context of the regulon are presented here, including Sec 14, Sec 4 and Sec 23. Other examined G. max homologs of membrane fusion genes include an endosomal bromo domain-containing protein1 (Bro1), syntaxin6 (SYP6), SYP131, SYP71, SYP8, Bet1, coatomer epsilon (ϵ-COP), a coatomer zeta (ζ-COP) paralog and an ER to Golgi component (ERGIC) protein. Furthermore, the effectiveness of biochemical pathways that would function within the context of the regulon ave been examined, including xyloglucan xylosyltransferase (XXT), reticuline oxidase (RO) and galactinol synthase (GS). The experiments have unveiled the importance of the regulon during defense in the root and show how the deposition of callose relates to the process.
Collapse
Affiliation(s)
- Vincent P. Klink
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS, USA
| | - Keshav Sharma
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS, USA
| | - Shankar R. Pant
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS, USA
| | - Brant McNeece
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS, USA
| | - Prakash Niraula
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS, USA
| | - Gary W. Lawrence
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State, MS, USA
| |
Collapse
|
34
|
Ma L, Rebane AA, Yang G, Xi Z, Kang Y, Gao Y, Zhang Y. Munc18-1-regulated stage-wise SNARE assembly underlying synaptic exocytosis. eLife 2015; 4. [PMID: 26701912 PMCID: PMC4744192 DOI: 10.7554/elife.09580] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 12/22/2015] [Indexed: 12/20/2022] Open
Abstract
Synaptic-soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) proteins couple their stage-wise folding/assembly to rapid exocytosis of neurotransmitters in a Munc18-1-dependent manner. The functions of the different assembly stages in exocytosis and the role of Munc18-1 in SNARE assembly are not well understood. Using optical tweezers, we observed four distinct stages of assembly in SNARE N-terminal, middle, C-terminal, and linker domains (or NTD, MD, CTD, and LD, respectively). We found that SNARE layer mutations differentially affect SNARE assembly. Comparison of their effects on SNARE assembly and on exocytosis reveals that NTD and CTD are responsible for vesicle docking and fusion, respectively, whereas MD regulates SNARE assembly and fusion. Munc18-1 initiates SNARE assembly and structures t-SNARE C-terminus independent of syntaxin N-terminal regulatory domain (NRD) and stabilizes the half-zippered SNARE complex dependent upon the NRD. Our observations demonstrate distinct functions of SNARE domains whose assembly is intimately chaperoned by Munc18-1. DOI:http://dx.doi.org/10.7554/eLife.09580.001 Plants, animals and other eukaryotes transport many large molecules within their cells inside membrane-bound packages called vesicles. These vesicles can fuse with the membrane of a target compartment in the cell to deliver their contents inside, or fuse with the cell’s membrane to release the contents outside of the cell. Membrane fusion is carried out by a group of proteins called SNAREs. These proteins are embedded on the membranes of both the vesicle and its target, and they bind to each other to form a tight complex. This complex docks the vesicle to the target and then acts like a “zipper” to pull the two membranes close enough to fuse. The best-studied SNARE proteins act in nerve cells and fuse vesicles to the cell’s membrane in order to release molecules called neurotransmitters. This process is essential for communication between nerve cells, and relies on a protein called Munc18-1. However, it is not well understood how SNARE proteins assemble into the complex and how Munc18-1 regulates this process. Ma et al. have now used a tool called “optical tweezers” to pull an assembled SNARE complex apart in the laboratory and then observe how it folds and assembles in a step-by-step process. These experiments showed that the complex assembled in four stages and not three as has been reported in previous work. SNARE proteins are made up of four parts called domains, and Ma et al. observed that the N-terminal domains were the first to bind to each other. Next, the binding progressed to the middle domain, then to the C-terminal domain and finally to the linker domain. An intermediate, half-zippered form was also observed. Ma et al. next analysed each domain in more detail and found that the N-terminal and C-terminal domains drive the docking of vesicles to the target membrane, the middle domain is crucial for assembling the SNARE complex correctly, and all three domains regulate the fusing of the membranes. Further experiments showed that Munc18-1 promoted the assembly of new SNARE complexes and stabilized the half-zippered form, rather than stabilizing the complex after it had fully assembled. This study will provide a new tool to examine many other proteins that regulate SNARE assembly, and a basis to understand the role of SNARE proteins in brain activity. DOI:http://dx.doi.org/10.7554/eLife.09580.002
Collapse
Affiliation(s)
- Lu Ma
- Department of Cell Biology, Yale School of Medicine, New Haven, United States
| | - Aleksander A Rebane
- Department of Cell Biology, Yale School of Medicine, New Haven, United States.,Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, United States.,Department of Physics, Yale University, New Haven, United States
| | - Guangcan Yang
- Department of Cell Biology, Yale School of Medicine, New Haven, United States.,Department of Physics, Wenzhou University, Wenzhou, China
| | - Zhiqun Xi
- Department of Cell Biology, Yale School of Medicine, New Haven, United States
| | - Yuhao Kang
- Department of Cell Biology, Yale School of Medicine, New Haven, United States
| | - Ying Gao
- Department of Cell Biology, Yale School of Medicine, New Haven, United States
| | - Yongli Zhang
- Department of Cell Biology, Yale School of Medicine, New Haven, United States
| |
Collapse
|