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Bykhovskaia M. Dynamic Formation of the Protein-Lipid Pre-fusion Complex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.17.589983. [PMID: 38659925 PMCID: PMC11042276 DOI: 10.1101/2024.04.17.589983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Synaptic vesicles (SVs) fuse with the presynaptic membrane (PM) to release neuronal transmitters. The SV protein Synaptotagmin 1 (Syt1) serves as a Ca2+ sensor for evoked fusion. Syt1 is thought to trigger fusion by penetrating into PM upon Ca2+ binding, however the mechanistic detail of this process is still debated. Syt1 interacts with the SNARE complex, a coiled-coil four-helical bundle that enables the SV-PM attachment. The SNARE-associated protein Complexin (Cpx) promotes the Ca2+-dependent fusion, possibly interacting with Syt1. We employed all-atom molecular dynamics (MD) to investigate the formation of the Syt1-SNARE-Cpx complex interacting with the lipid bilayers of PM and SV. Our simulations demonstrated that the PM-Syt1-SNARE-Cpx complex can transition to a "dead-end" state, wherein Syt1 attaches tightly to PM but does not immerse into it, as opposed to a pre-fusion state, which has the tips of the Ca2+-bound C2 domains of Syt1 inserted into PM. Our simulations unraveled the sequence of Syt1 conformational transitions, including the simultaneous Syt1 docking to the SNARE-Cpx bundle and PM, followed by the Ca2+ chelation and the penetration of the tips of Syt1 domains into PM, leading to the pre-fusion state of the protein-lipid complex. Importantly, we found that the direct Syt1-Cpx interactions are required to promote these transitions. Thus, we developed the all-atom dynamic model of the conformational transitions that lead to the formation of the pre-fusion PM-Syt1-SNARE-Cpx complex. Our simulations also revealed an alternative "dead-end" state of the protein-lipid complex that can be formed if this pathway is disrupted.
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2
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Huang W, Yang Y, Che F, Wu H, Ma Y, Zhao Y. Lethal variant in the C2A domain may cause severe SYT1-associated neurodevelopmental disorder in the newborns. Neurogenetics 2024; 25:27-31. [PMID: 37930470 DOI: 10.1007/s10048-023-00738-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 10/22/2023] [Indexed: 11/07/2023]
Abstract
Synaptotagmin-1 (SYT1) plays a pivotal role in regulating presynaptic processes, including neurotransmitter release. SYT1 variants perturb synaptic vesicle endocytosis and exocytosis, resulting in a series of neurodevelopmental disorders defined as Baker-Gordon syndrome. Herein, we report the case of a newborn with dysmorphic facial appearance, severe hypotonia, poor feeding, gastroesophageal reflux, and an inability to eat and breathe, diagnosed with Baker-Gordon syndrome. A retrospective search was performed on a newborn with Baker-Gordon syndrome. Medical charts were reviewed, with focus on the clinical presentation, diagnostic process, and treatment outcomes. Whole-genome high-throughput DNA sequencing was performed to identify genetic variants. Whole-exome sequencing identified the likely pathogenic variant as SYT1 C.551 T > C(p.V184A). Sanger sequencing results indicated that this variant was a de novo mutation in a conservative site located in the C2A domain of the protein. The patient died at 57 days old because of severe feeding and breathing problems. Our findings of a novel lethal variant in the C2A domain of SYT1 in the youngest patient diagnosed infantile Baker-Gordon syndrome who presented with the most severe hypotonia reported to date expands the spectrum of SYT1- associated neurodevelopmental disorders.
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Affiliation(s)
- Wendi Huang
- Department of Neonatology, Xi'an Children's Hospital, No. 69 Xijuyuan Lane, Lianhu District, Xi'an City, 710003, Shaanxi, China
| | - Ying Yang
- Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Xi'an, China
| | - Fengyu Che
- Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Xi'an, China
| | - Haibin Wu
- Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Xi'an, China
| | - Ying Ma
- Department of Neonatology, Xi'an Children's Hospital, No. 69 Xijuyuan Lane, Lianhu District, Xi'an City, 710003, Shaanxi, China
| | - Yujuan Zhao
- Department of Neonatology, Xi'an Children's Hospital, No. 69 Xijuyuan Lane, Lianhu District, Xi'an City, 710003, Shaanxi, China.
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3
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Ali Moussa HY, Shin KC, Ponraj J, Kim SJ, Ryu JK, Mansour S, Park Y. Requirement of Cholesterol for Calcium-Dependent Vesicle Fusion by Strengthening Synaptotagmin-1-Induced Membrane Bending. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2206823. [PMID: 37058136 DOI: 10.1002/advs.202206823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 02/09/2023] [Indexed: 05/27/2023]
Abstract
Cholesterol is essential for neuronal activity and function. Cholesterol depletion in the plasma membrane impairs synaptic transmission. However, the molecular mechanisms by which cholesterol deficiency leads to defects in vesicle fusion remain poorly understood. Here, it is shown that cholesterol is required for Ca2+ -dependent native vesicle fusion using the in vitro reconstitution of fusion and amperometry to monitor exocytosis in chromaffin cells. Purified native vesicles are crucial for the reconstitution of physiological Ca2+ -dependent fusion, because vesicle-mimicking liposomes fail to reproduce the cholesterol effect. Intriguingly, cholesterol has no effect on the membrane binding of synaptotagmin-1, a Ca2+ sensor for ultrafast fusion. Cholesterol strengthens local membrane deformation and bending induced by synaptotagmin-1, thereby lowering the energy barrier for Ca2+ -dependent fusion to occur. The data provide evidence that cholesterol depletion abolishes Ca2+ -dependent vesicle fusion by disrupting synaptotagmin-1-induced membrane bending, and suggests that cholesterol is an essential lipid regulator for Ca2+ -dependent fusion.
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Affiliation(s)
- Houda Yasmine Ali Moussa
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | - Kyung Chul Shin
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | | | - Soo Jin Kim
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Republic of Korea
| | - Je-Kyung Ryu
- Department of Physics & Astronomy, Seoul National University. 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea
| | - Said Mansour
- HBKU Core Labs, Hamad Bin Khalifa University (HBKU), Doha, Qatar
| | - Yongsoo Park
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
- College of Health & Life Sciences (CHLS), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
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Uzay B, Kavalali ET. Genetic disorders of neurotransmitter release machinery. Front Synaptic Neurosci 2023; 15:1148957. [PMID: 37066095 PMCID: PMC10102358 DOI: 10.3389/fnsyn.2023.1148957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 03/10/2023] [Indexed: 04/03/2023] Open
Abstract
Synaptic neurotransmitter release is an evolutionarily conserved process that mediates rapid information transfer between neurons as well as several peripheral tissues. Release of neurotransmitters are ensured by successive events such as synaptic vesicle docking and priming that prepare synaptic vesicles for rapid fusion. These events are orchestrated by interaction of different presynaptic proteins and are regulated by presynaptic calcium. Recent studies have identified various mutations in different components of neurotransmitter release machinery resulting in aberrant neurotransmitter release, which underlie a wide spectrum of psychiatric and neurological symptoms. Here, we review how these genetic alterations in different components of the core neurotransmitter release machinery affect the information transfer between neurons and how aberrant synaptic release affects nervous system function.
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Affiliation(s)
- Burak Uzay
- Vanderbilt Brain Institute, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - Ege T. Kavalali
- Vanderbilt Brain Institute, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States
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5
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Prakash S, Krishna A, Sengupta D. Cofilin-Membrane Interactions: Electrostatic Effects in Phosphoinositide Lipid Binding. Chemphyschem 2023; 24:e202200509. [PMID: 36200760 DOI: 10.1002/cphc.202200509] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 10/06/2022] [Indexed: 02/04/2023]
Abstract
The actin cytoskeleton interacts with the cell membrane primarily through the indirect interactions of actin-binding proteins such as cofilin-1. The molecular mechanisms underlying the specific interactions of cofilin-1 with membrane lipids are still unclear. Here, we performed coarse-grain molecular dynamics simulations of cofilin-1 with complex lipid bilayers to analyze the specificity of protein-lipid interactions. We observed the maximal interactions with phosphoinositide (PIP) lipids, especially PIP2 and PIP3 lipids. A good match was observed between the residues predicted to interact and previous experimental studies. The clustering of PIP lipids around the membrane bound protein leads to an overall lipid demixing and gives rise to persistent membrane curvature. Further, through a series of control simulations, we observe that both electrostatics and geometry are critical for specificity of lipid binding. Our current study is a step towards understanding the physico-chemical basis of cofilin-PIP lipid interactions.
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Affiliation(s)
- Shikha Prakash
- CSIR - National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India
| | - Anjali Krishna
- CSIR - National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India.,Current Address: School of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
| | - Durba Sengupta
- CSIR - National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India
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Palfreyman MT, West SE, Jorgensen EM. SNARE Proteins in Synaptic Vesicle Fusion. ADVANCES IN NEUROBIOLOGY 2023; 33:63-118. [PMID: 37615864 DOI: 10.1007/978-3-031-34229-5_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Neurotransmitters are stored in small membrane-bound vesicles at synapses; a subset of synaptic vesicles is docked at release sites. Fusion of docked vesicles with the plasma membrane releases neurotransmitters. Membrane fusion at synapses, as well as all trafficking steps of the secretory pathway, is mediated by SNARE proteins. The SNAREs are the minimal fusion machinery. They zipper from N-termini to membrane-anchored C-termini to form a 4-helix bundle that forces the apposed membranes to fuse. At synapses, the SNAREs comprise a single helix from syntaxin and synaptobrevin; SNAP-25 contributes the other two helices to complete the bundle. Unc13 mediates synaptic vesicle docking and converts syntaxin into the permissive "open" configuration. The SM protein, Unc18, is required to initiate and proofread SNARE assembly. The SNAREs are then held in a half-zippered state by synaptotagmin and complexin. Calcium removes the synaptotagmin and complexin block, and the SNAREs drive vesicle fusion. After fusion, NSF and alpha-SNAP unwind the SNAREs and thereby recharge the system for further rounds of fusion. In this chapter, we will describe the discovery of the SNAREs, their relevant structural features, models for their function, and the central role of Unc18. In addition, we will touch upon the regulation of SNARE complex formation by Unc13, complexin, and synaptotagmin.
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Affiliation(s)
- Mark T Palfreyman
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Sam E West
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Erik M Jorgensen
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA.
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Riggs E, Shakkour Z, Anderson CL, Carney PR. SYT1-Associated Neurodevelopmental Disorder: A Narrative Review. CHILDREN 2022; 9:children9101439. [PMID: 36291375 PMCID: PMC9601251 DOI: 10.3390/children9101439] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/13/2022] [Accepted: 09/15/2022] [Indexed: 11/16/2022]
Abstract
Synaptic dysregulations often result in damaging effects on the central nervous system, resulting in a wide range of brain and neurodevelopment disorders that are caused by mutations disrupting synaptic proteins. SYT1, an identified synaptotagmin protein, plays an essential role in mediating the release of calcium-triggered neurotransmitters (NT) involved in regular synaptic vesicle exocytosis. Considering the significant role of SYT1 in the physiology of synaptic neurotransmission, dysfunction and degeneration of this protein can result in a severe neurological impairment. Genetic variants lead to a newly discovered rare disorder, known as SYT1-associated neurodevelopment disorder. In this review, we will discuss in depth the function of SYT1 in synapse and the underlying molecular mechanisms. We will highlight the genetic basis of SYT1-associated neurodevelopmental disorder along with known phenotypes, with possible interventions and direction of research.
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Affiliation(s)
- Edith Riggs
- College of Osteopathic Medicine, Kansas City University School of Medicine, Kansas City, MO 64106, USA
| | - Zaynab Shakkour
- School of Medicine, University of Missouri Child Health, Columbia, MO 65201, USA
| | - Christopher L. Anderson
- School of Medicine, University of Missouri Child Health, Columbia, MO 65201, USA
- Correspondence:
| | - Paul R. Carney
- School of Medicine, University of Missouri Child Health, Columbia, MO 65201, USA
- Department of Engineering, University of Missouri Biomedical Engineering, Columbia, MO 65201, USA
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8
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Kobbersmed JRL, Berns MMM, Ditlevsen S, Sørensen JB, Walter AM. Allosteric stabilization of calcium and phosphoinositide dual binding engages several synaptotagmins in fast exocytosis. eLife 2022; 11:74810. [PMID: 35929728 PMCID: PMC9489213 DOI: 10.7554/elife.74810] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 08/04/2022] [Indexed: 12/04/2022] Open
Abstract
Synaptic communication relies on the fusion of synaptic vesicles with the plasma membrane, which leads to neurotransmitter release. This exocytosis is triggered by brief and local elevations of intracellular Ca2+ with remarkably high sensitivity. How this is molecularly achieved is unknown. While synaptotagmins confer the Ca2+ sensitivity of neurotransmitter exocytosis, biochemical measurements reported Ca2+ affinities too low to account for synaptic function. However, synaptotagmin’s Ca2+ affinity increases upon binding the plasma membrane phospholipid PI(4,5)P2 and, vice versa, Ca2+ binding increases synaptotagmin’s PI(4,5)P2 affinity, indicating a stabilization of the Ca2+/PI(4,5)P2 dual-bound state. Here, we devise a molecular exocytosis model based on this positive allosteric stabilization and the assumptions that (1.) synaptotagmin Ca2+/PI(4,5)P2 dual binding lowers the energy barrier for vesicle fusion and that (2.) the effect of multiple synaptotagmins on the energy barrier is additive. The model, which relies on biochemically measured Ca2+/PI(4,5)P2 affinities and protein copy numbers, reproduced the steep Ca2+ dependency of neurotransmitter release. Our results indicate that each synaptotagmin engaging in Ca2+/PI(4,5)P2 dual-binding lowers the energy barrier for vesicle fusion by ~5 kBT and that allosteric stabilization of this state enables the synchronized engagement of several (typically three) synaptotagmins for fast exocytosis. Furthermore, we show that mutations altering synaptotagmin’s allosteric properties may show dominant-negative effects, even though synaptotagmins act independently on the energy barrier, and that dynamic changes of local PI(4,5)P2 (e.g. upon vesicle movement) dramatically impact synaptic responses. We conclude that allosterically stabilized Ca2+/PI(4,5)P2 dual binding enables synaptotagmins to exert their coordinated function in neurotransmission. For our brains and nervous systems to work properly, the nerve cells within them must be able to ‘talk’ to each other. They do this by releasing chemical signals called neurotransmitters which other cells can detect and respond to. Neurotransmitters are packaged in tiny membrane-bound spheres called vesicles. When a cell of the nervous system needs to send a signal to its neighbours, the vesicles fuse with the outer membrane of the cell, discharging their chemical contents for other cells to detect. The initial trigger for neurotransmitter release is a short, fast increase in the amount of calcium ions inside the signalling cell. One of the main proteins that helps regulate this process is synaptotagmin which binds to calcium and gives vesicles the signal to start unloading their chemicals. Despite acting as a calcium sensor, synaptotagmin actually has a very low affinity for calcium ions by itself, meaning that it would not be efficient for the protein to respond alone. Synpatotagmin is more likely to bind to calcium if it is attached to a molecule called PIP2, which is found in the membranes of cells The effect also occurs in reverse, as the binding of calcium to synaptotagmin increases the protein’s affinity for PIP2. However, how these three molecules – synaptotagmin, PIP2, and calcium – work together to achieve the physiological release of neurotransmitters is poorly understood. To help answer this question, Kobbersmed, Berns et al. set up a computer simulation of ‘virtual vesicles’ using available experimental data on synaptotagmin’s affinity with calcium and PIP2. In this simulation, synaptotagmin could only trigger the release of neurotransmitters when bound to both calcium and PIP2. The model also showed that each ‘complex’ of synaptotagmin/calcium/PIP2 made the vesicles more likely to fuse with the outer membrane of the cell – to the extent that only a handful of synaptotagmin molecules were needed to start neurotransmitter release from a single vesicle. These results shed new light on a biological process central to the way nerve cells communicate with each other. In the future, Kobbersmed, Berns et al. hope that this insight will help us to understand the cause of diseases where communication in the nervous system is impaired.
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Affiliation(s)
- Janus R L Kobbersmed
- Department of Mathematical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Manon M M Berns
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Susanne Ditlevsen
- Department of Mathematical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Alexander M Walter
- Department of Mathematical Sciences, University of Copenhagen, Copenhagen, Denmark
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9
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Ma X, Li X, Wang W, Zhang M, Yang B, Miao Z. Phosphatidylserine, inflammation, and central nervous system diseases. Front Aging Neurosci 2022; 14:975176. [PMID: 35992593 PMCID: PMC9382310 DOI: 10.3389/fnagi.2022.975176] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 07/15/2022] [Indexed: 11/13/2022] Open
Abstract
Phosphatidylserine (PS) is an anionic phospholipid in the eukaryotic membrane and is abundant in the brain. Accumulated studies have revealed that PS is involved in the multiple functions of the brain, such as activation of membrane signaling pathways, neuroinflammation, neurotransmission, and synaptic refinement. Those functions of PS are related to central nervous system (CNS) diseases. In this review, we discuss the metabolism of PS, the anti-inflammation function of PS in the brain; the alterations of PS in different CNS diseases, and the possibility of PS to serve as a therapeutic agent for diseases. Clinical studies have showed that PS has no side effects and is well tolerated. Therefore, PS and PS liposome could be a promising supplementation for these neurodegenerative and neurodevelopmental diseases.
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Affiliation(s)
- Xiaohua Ma
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, China
- Institute of Neuroscience, Soochow University, Suzhou, China
| | - Xiaojing Li
- Suzhou Science and Technology Town Hospital, Suzhou, China
| | - Wenjuan Wang
- Institute of Neuroscience, Soochow University, Suzhou, China
| | - Meng Zhang
- Institute of Neuroscience, Soochow University, Suzhou, China
| | - Bo Yang
- Department of Anesthesiology, The Second Affiliated Hospital of Soochow University, Suzhou, China
- *Correspondence: Bo Yang,
| | - Zhigang Miao
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, China
- Institute of Neuroscience, Soochow University, Suzhou, China
- Zhigang Miao,
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10
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Grauffel C, Weng WH, Lim C. Factors allowing small monovalent Li + to displace Ca 2+ in proteins. Phys Chem Chem Phys 2022; 24:17759-17769. [PMID: 35848546 DOI: 10.1039/d2cp02072f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Because Li+ and Ca2+ differ in both charge and size, the possibility that monovalent Li+ could dislodge the bulkier, divalent Ca2+ in Ca2+ proteins had not been considered. However, our recent density functional theory/continuum dielectric calculations predicted that Li+ could displace the native Ca2+ from the C2 domain of cytosolic PKCα/γ. This would reduce electrostatic interactions between the Li+-bound C2 domain and the membrane, consistent with experimental studies showing that Li+ can inhibit the translocation of cytoplasmic PKC to membranes. Besides the trinuclear Ca2+-site in the PKCα/γ C2 domain, it is not known whether other Ca2+-sites in human proteins may be susceptible to Li+ substitution. Furthermore, it is unclear what factors determine the outcome of the competition between divalent Ca2+ and monovalent Li+. Here we show that the net charge of residues in the first and second coordination shell is a key determinant of the selectivity for divalent Ca2+ over monovalent Li+ in proteins: neutral/anionic Ca2+-carboxylate sites are protected against Li+ attack. They are further protected by outer-shell Asp-/Glu- and the protein matrix rigidifying the Ca2+-site or limiting water entry. In contrast, buried, cationic Ca2+-sites surrounded by Arg+/Lys+, which are found in the C2 domains of PKCα/γ, as well as certain synaptotagmins, are prone to Li+ attack.
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Affiliation(s)
- Cédric Grauffel
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan.
| | - Wei-Hsiang Weng
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan.
| | - Carmay Lim
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan. .,Department of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan
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11
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Dietz J, Oelkers M, Hubrich R, Pérez-Lara A, Jahn R, Steinem C, Janshoff A. Forces, Kinetics, and Fusion Efficiency Altered by the Full-Length Synaptotagmin-1 -PI(4,5)P 2 Interaction in Constrained Geometries. NANO LETTERS 2022; 22:1449-1455. [PMID: 34855407 DOI: 10.1021/acs.nanolett.1c02491] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
A mechanism for full-length synaptotagmin-1 (syt-1) to interact with anionic bilayers and to promote fusion in the presence of SNAREs is proposed. Colloidal probe force spectroscopy in conjunction with tethered particle motion monitoring showed that in the absence of Ca2+ the binding of syt-1 to membranes depends on the presence and content of PI(4,5)P2. Addition of Ca2+ switches the interaction forces from weak to strong, eventually exceeding the cohesion of the C2A domain of syt-1 leading to partial unfolding of the protein. Fusion of single unilamellar vesicles equipped with syt-1 and synaptobrevin 2 with planar pore-spanning target membranes containing PS and PI(4,5)P2 shows an almost complete suppression of stalled intermediate fusion states and an accelerated fusion kinetics in the presence of Ca2+, which is further enhanced upon addition of ATP.
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Affiliation(s)
- Joern Dietz
- Institute for Physical Chemistry, Georg-August Universität, Tammannstr. 6, 37077 Göttingen, Germany
| | - Marieelen Oelkers
- Institute for Physical Chemistry, Georg-August Universität, Tammannstr. 6, 37077 Göttingen, Germany
| | - Raphael Hubrich
- Institute for Organic and Biomolecular Chemistry, Georg-August Universität, Tammannstr. 2, 37077 Göttingen, Germany
| | - Angel Pérez-Lara
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Am Faβberg 11, 37077 Göttingen, Germany
| | - Reinhard Jahn
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Am Faβberg 11, 37077 Göttingen, Germany
| | - Claudia Steinem
- Institute for Organic and Biomolecular Chemistry, Georg-August Universität, Tammannstr. 2, 37077 Göttingen, Germany
| | - Andreas Janshoff
- Institute for Physical Chemistry, Georg-August Universität, Tammannstr. 6, 37077 Göttingen, Germany
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12
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Di Bartolo AL, Masone D. Synaptotagmin-1 C2B domains cooperatively stabilize the fusion stalk via a master-servant mechanism. Chem Sci 2022; 13:3437-3446. [PMID: 35432859 PMCID: PMC8943895 DOI: 10.1039/d1sc06711g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 02/22/2022] [Indexed: 11/21/2022] Open
Abstract
Synaptotagmin-1 is a low-affinity Ca2+ sensor that triggers synchronous vesicle fusion. It contains two similar C2 domains (C2A and C2B) that cooperate in membrane binding, being the C2B domain the...
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Affiliation(s)
- Ary Lautaro Di Bartolo
- Instituto de Histología y Embriología de Mendoza (IHEM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo (UNCuyo) 5500 Mendoza Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo (UNCuyo) 5500 Mendoza Argentina
| | - Diego Masone
- Instituto de Histología y Embriología de Mendoza (IHEM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo (UNCuyo) 5500 Mendoza Argentina
- Facultad de Ingeniería, Universidad Nacional de Cuyo (UNCuyo) 5500 Mendoza Argentina
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13
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Tagoe DNA, Drozda AA, Falco JA, Bechtel TJ, Weerapana E, Gubbels MJ. Ferlins and TgDOC2 in Toxoplasma Microneme, Rhoptry and Dense Granule Secretion. Life (Basel) 2021; 11:217. [PMID: 33803212 PMCID: PMC7999867 DOI: 10.3390/life11030217] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 03/02/2021] [Accepted: 03/05/2021] [Indexed: 12/25/2022] Open
Abstract
The host cell invasion process of apicomplexan parasites like Toxoplasma gondii is facilitated by sequential exocytosis of the microneme, rhoptry and dense granule organelles. Exocytosis is facilitated by a double C2 domain (DOC2) protein family. This class of C2 domains is derived from an ancestral calcium (Ca2+) binding archetype, although this feature is optional in extant C2 domains. DOC2 domains provide combinatorial power to the C2 domain, which is further enhanced in ferlins that harbor 5-7 C2 domains. Ca2+ conditionally engages the C2 domain with lipids, membranes, and/or proteins to facilitating vesicular trafficking and membrane fusion. The widely conserved T. gondii ferlins 1 (FER1) and 2 (FER2) are responsible for microneme and rhoptry exocytosis, respectively, whereas an unconventional TgDOC2 is essential for microneme exocytosis. The general role of ferlins in endolysosmal pathways is consistent with the repurposed apicomplexan endosomal pathways in lineage specific secretory organelles. Ferlins can facilitate membrane fusion without SNAREs, again pertinent to the Apicomplexa. How temporal raises in Ca2+ combined with spatiotemporally available membrane lipids and post-translational modifications mesh to facilitate sequential exocytosis events is discussed. In addition, new data on cross-talk between secretion events together with the identification of a new microneme protein, MIC21, is presented.
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Affiliation(s)
- Daniel N. A. Tagoe
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA; (D.N.A.T.); (A.A.D.)
| | - Allison A. Drozda
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA; (D.N.A.T.); (A.A.D.)
| | - Julia A. Falco
- Department of Chemistry, Boston College, Chestnut Hill, MA 02467, USA; (J.A.F.); (T.J.B.); (E.W.)
| | - Tyler J. Bechtel
- Department of Chemistry, Boston College, Chestnut Hill, MA 02467, USA; (J.A.F.); (T.J.B.); (E.W.)
| | - Eranthie Weerapana
- Department of Chemistry, Boston College, Chestnut Hill, MA 02467, USA; (J.A.F.); (T.J.B.); (E.W.)
| | - Marc-Jan Gubbels
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA; (D.N.A.T.); (A.A.D.)
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