1
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Wang Y, Zhu Y, Li W, Yan S, Li C, Ma K, Hu M, Du C, Fu L, Sun J, Zhang CX. Synaptotagmin-11 Inhibits Synaptic Vesicle Endocytosis via Endophilin A1. J Neurosci 2023; 43:6230-6248. [PMID: 37474308 PMCID: PMC10490507 DOI: 10.1523/jneurosci.1348-21.2023] [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: 06/29/2021] [Revised: 05/12/2023] [Accepted: 06/02/2023] [Indexed: 07/22/2023] Open
Abstract
Synaptic vesicle (SV) endocytosis is a critical and well-regulated process for the maintenance of neurotransmission. We previously reported that synaptotagmin-11 (Syt11), an essential non-Ca2+-binding Syt associated with brain diseases, inhibits neuronal endocytosis (Wang et al., 2016). Here, we found that Syt11 deficiency caused accelerated SV endocytosis and vesicle recycling under sustained stimulation and led to the abnormal membrane partition of synaptic proteins in mouse hippocampal boutons of either sex. Furthermore, our study revealed that Syt11 has direct but Ca2+-independent binding with endophilin A1 (EndoA1), a membrane curvature sensor and endocytic protein recruiter, with high affinity. EndoA1-knockdown significantly reversed Syt11-KO phenotype, identifying EndoA1 as a main inhibitory target of Syt11 during SV endocytosis. The N-terminus of EndoA1 and the C2B domain of Syt11 were responsible for this interaction. A peptide (amino acids 314-336) derived from the Syt11 C2B efficiently blocked Syt11-EndoA1 binding both in vitro and in vivo Application of this peptide inhibited SV endocytosis in WT hippocampal neurons but not in EndoA1-knockdown neurons. Moreover, intracellular application of this peptide in mouse calyx of Held terminals of either sex effectively hampered both fast and slow SV endocytosis at physiological temperature. We thus propose that Syt11 ensures the precision of protein retrieval during SV endocytosis by inhibiting EndoA1 function at neuronal terminals.SIGNIFICANCE STATEMENT Endocytosis is a key stage of synaptic vesicle (SV) recycling. SV endocytosis retrieves vesicular membrane and protein components precisely to support sustained neurotransmission. However, the molecular mechanisms underlying the regulation of SV endocytosis remain elusive. Here, we reported that Syt11-KO accelerated SV endocytosis and impaired membrane partition of synaptic proteins. EndoA1 was identified as a main inhibitory target of Syt11 during SV endocytosis. Our study reveals a novel inhibitory mechanism of SV endocytosis in preventing hyperactivation of endocytosis, potentially safeguarding the recycling of synaptic proteins during sustained neurotransmission.
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Affiliation(s)
- Yalong Wang
- Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences; CAS Key Laboratory of Brain Connectome and Manipulation; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, Guangdong 518055, China
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Ying Zhu
- State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wanru Li
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Shuxin Yan
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Chao Li
- State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Kunpeng Ma
- Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences; CAS Key Laboratory of Brain Connectome and Manipulation; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, Guangdong 518055, China
| | - Meiqin Hu
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109
| | - Cuilian Du
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Lei Fu
- Academy of Pharmacy, Xi'an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
| | - Jianyuan Sun
- Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences; CAS Key Laboratory of Brain Connectome and Manipulation; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, Guangdong 518055, China
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, 100069, China
- State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Claire Xi Zhang
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, 100069, China
- Academy of Pharmacy, Xi'an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
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2
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Multivalent interactions between molecular components involved in fast endophilin mediated endocytosis drive protein phase separation. Nat Commun 2022; 13:5017. [PMID: 36028485 PMCID: PMC9418313 DOI: 10.1038/s41467-022-32529-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 08/03/2022] [Indexed: 11/30/2022] Open
Abstract
A specific group of transmembrane receptors, including the β1-adrenergic receptor (β1-AR), is internalized through a non-clathrin pathway known as Fast Endophilin Mediated Endocytosis (FEME). A key question is: how does the endocytic machinery assemble and how is it modulated by activated receptors during FEME. Here we show that endophilin, a major regulator of FEME, undergoes a phase transition into liquid-like condensates, which facilitates the formation of multi-protein assemblies by enabling the phase partitioning of endophilin binding proteins. The phase transition can be triggered by specific multivalent binding partners of endophilin in the FEME pathway such as the third intracellular loop (TIL) of the β1-AR, and the C-terminal domain of lamellipodin (LPD). Other endocytic accessory proteins can either partition into, or target interfacial regions of, these condensate droplets, and LPD also phase separates with the actin polymerase VASP. On the membrane, TIL promotes protein clustering in the presence of endophilin and LPD C-terminal domain. Our results demonstrate how the multivalent interactions between endophilin, LPD, and TIL regulate protein assembly formation on the membrane, providing mechanistic insights into the priming and initiation steps of FEME. Here the authors show that protein phase separation is a key mechanism in cellular receptor internalization via fast endophilin mediated endocytosis (FEME). Phase separation facilitates multivalent FEME-protein assembly in this clathrin-independent pathway.
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3
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Zhang L, Wang Y, Dong Y, Pant A, Liu Y, Masserman L, Xu Y, McLaughlin RN, Bai J. The endophilin curvature-sensitive motif requires electrostatic guidance to recycle synaptic vesicles in vivo. Dev Cell 2022; 57:750-766.e5. [PMID: 35303431 PMCID: PMC8969179 DOI: 10.1016/j.devcel.2022.02.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 01/21/2022] [Accepted: 02/22/2022] [Indexed: 12/29/2022]
Abstract
Curvature-sensing mechanisms assist proteins in executing particular actions on various membrane organelles. Here, we investigate the functional specificity of curvature-sensing amphipathic motifs in Caenorhabditis elegans through the study of endophilin, an endocytic protein for synaptic vesicle recycling. We generate chimeric endophilin proteins by replacing the endophilin amphipathic motif H0 with other curvature-sensing amphipathic motifs. We find that the role of amphipathic motifs cannot simply be extrapolated from the identity of their parental proteins. For example, the amphipathic motif of the nuclear pore complex protein NUP133 functionally replaces the synaptic role of endophilin H0. Interestingly, non-functional endophilin chimeras have similar defects-producing fewer synaptic vesicles but more endosomes-and this indicates that the curvature-sensing motifs in these chimeras have a common deficiency for reforming synaptic vesicles. Finally, we convert non-functional endophilin chimeras into functional proteins by changing the cationic property of amphipathic motifs, successfully reprogramming the functional specificity of curvature-sensing motifs in vivo.
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Affiliation(s)
- Lin Zhang
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Yu Wang
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, P.R. China; Fudan University, Shanghai 200433, P.R. China
| | - Yongming Dong
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Aaradhya Pant
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Yan Liu
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Laura Masserman
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Ye Xu
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | | | - Jihong Bai
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
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4
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Aryal CM, Bui NN, Khadka NK, Song L, Pan J. The helix 0 of endophilin modifies membrane material properties and induces local curvature. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183397. [PMID: 32533976 DOI: 10.1016/j.bbamem.2020.183397] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 06/04/2020] [Accepted: 06/09/2020] [Indexed: 11/26/2022]
Abstract
The amphipathic helix 0 of endophilin (i.e., H0-Endo) is important to membrane binding, but its function of curvature generation remains controversial. We used electron paramagnetic resonance (EPR) spectroscopy to study effects of H0-Endo on membrane material properties. We found that H0-Endo reduced lipid chain mobility and increased bilayer polarity, i.e., making the bilayer interior more polar. Lipid-dependent examination revealed that anionic lipids augmented the effect of H0-Endo, while cholesterol had a minimal impact. Our EPR spectroscopy of magnetically aligned bicelles showed that as the peptide-to-lipid ratio increased, the lipid chain orientational order decreased gradually, followed by a sudden loss. We discuss an interfacial-bound model of the amphipathic H0-Endo to account for all EPR data. We used atomic force microscopy and fluorescence microscopy to explore membrane morphological changes. We found that H0-Endo caused the formation of micron-sized holes in mica-supported planar bilayers. Hole formation is likely caused by two competing forces - the adhesion force exerted by the substrate represses bilayer budging, whereas the line tension originating from peptide clustering has a tendency of destabilizing bilayer organization. In the absence of substrate influences, membrane curvature induction was manifested by generating small vesicles surrounding giant unilamellar vesicles. Our results of membrane perforation and vesiculation suggest that the functionality of H0-Endo is more than just coordinating membrane binding of endophilin.
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Affiliation(s)
- Chinta M Aryal
- Department of Physics, University of South Florida, Tampa, FL 33620, United States of America
| | - Nhat Nguyen Bui
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, United States of America
| | - Nawal K Khadka
- Department of Physics, University of South Florida, Tampa, FL 33620, United States of America
| | - Likai Song
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, United States of America.
| | - Jianjun Pan
- Department of Physics, University of South Florida, Tampa, FL 33620, United States of America.
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5
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Zhukovsky MA, Filograna A, Luini A, Corda D, Valente C. Protein Amphipathic Helix Insertion: A Mechanism to Induce Membrane Fission. Front Cell Dev Biol 2019; 7:291. [PMID: 31921835 PMCID: PMC6914677 DOI: 10.3389/fcell.2019.00291] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 11/06/2019] [Indexed: 12/19/2022] Open
Abstract
One of the fundamental features of biomembranes is the ability to fuse or to separate. These processes called respectively membrane fusion and fission are central in the homeostasis of events such as those related to intracellular membrane traffic. Proteins that contain amphipathic helices (AHs) were suggested to mediate membrane fission via shallow insertion of these helices into the lipid bilayer. Here we analyze the AH-containing proteins that have been identified as essential for membrane fission and categorize them in few subfamilies, including small GTPases, Atg proteins, and proteins containing either the ENTH/ANTH- or the BAR-domain. AH-containing fission-inducing proteins may require cofactors such as additional proteins (e.g., lipid-modifying enzymes), or lipids (e.g., phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2], phosphatidic acid [PA], or cardiolipin). Both PA and cardiolipin possess a cone shape and a negative charge (-2) that favor the recruitment of the AHs of fission-inducing proteins. Instead, PtdIns(4,5)P2 is characterized by an high negative charge able to recruit basic residues of the AHs of fission-inducing proteins. Here we propose that the AHs of fission-inducing proteins contain sequence motifs that bind lipid cofactors; accordingly (K/R/H)(K/R/H)xx(K/R/H) is a PtdIns(4,5)P2-binding motif, (K/R)x6(F/Y) is a cardiolipin-binding motif, whereas KxK is a PA-binding motif. Following our analysis, we show that the AHs of many fission-inducing proteins possess five properties: (a) at least three basic residues on the hydrophilic side, (b) ability to oligomerize, (c) optimal (shallow) depth of insertion into the membrane, (d) positive cooperativity in membrane curvature generation, and (e) specific interaction with one of the lipids mentioned above. These lipid cofactors favor correct conformation, oligomeric state and optimal insertion depth. The most abundant lipid in a given organelle possessing high negative charge (more negative than -1) is usually the lipid cofactor in the fission event. Interestingly, naturally occurring mutations have been reported in AH-containing fission-inducing proteins and related to diseases such as centronuclear myopathy (amphiphysin 2), Charcot-Marie-Tooth disease (GDAP1), Parkinson's disease (α-synuclein). These findings add to the interest of the membrane fission process whose complete understanding will be instrumental for the elucidation of the pathogenesis of diseases involving mutations in the protein AHs.
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Affiliation(s)
- Mikhail A. Zhukovsky
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | | | | | - Daniela Corda
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Carmen Valente
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
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6
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Muller MP, Jiang T, Sun C, Lihan M, Pant S, Mahinthichaichan P, Trifan A, Tajkhorshid E. Characterization of Lipid-Protein Interactions and Lipid-Mediated Modulation of Membrane Protein Function through Molecular Simulation. Chem Rev 2019; 119:6086-6161. [PMID: 30978005 PMCID: PMC6506392 DOI: 10.1021/acs.chemrev.8b00608] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The cellular membrane constitutes one of the most fundamental compartments of a living cell, where key processes such as selective transport of material and exchange of information between the cell and its environment are mediated by proteins that are closely associated with the membrane. The heterogeneity of lipid composition of biological membranes and the effect of lipid molecules on the structure, dynamics, and function of membrane proteins are now widely recognized. Characterization of these functionally important lipid-protein interactions with experimental techniques is however still prohibitively challenging. Molecular dynamics (MD) simulations offer a powerful complementary approach with sufficient temporal and spatial resolutions to gain atomic-level structural information and energetics on lipid-protein interactions. In this review, we aim to provide a broad survey of MD simulations focusing on exploring lipid-protein interactions and characterizing lipid-modulated protein structure and dynamics that have been successful in providing novel insight into the mechanism of membrane protein function.
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Affiliation(s)
- Melanie P. Muller
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- College of Medicine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Tao Jiang
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Chang Sun
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Muyun Lihan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Shashank Pant
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Paween Mahinthichaichan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Anda Trifan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Emad Tajkhorshid
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- College of Medicine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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7
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Simunovic M, Šarić A, Henderson JM, Lee KYC, Voth GA. Long-Range Organization of Membrane-Curving Proteins. ACS CENTRAL SCIENCE 2017; 3:1246-1253. [PMID: 29296664 PMCID: PMC5746856 DOI: 10.1021/acscentsci.7b00392] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Indexed: 05/02/2023]
Abstract
Biological membranes have a central role in mediating the organization of membrane-curving proteins, a dynamic process that has proven to be challenging to probe experimentally. Using atomic force microscopy, we capture the hierarchically organized assemblies of Bin/amphiphysin/Rvs (BAR) proteins on supported lipid membranes. Their structure reveals distinct long linear aggregates of proteins, regularly spaced by up to 300 nm. Employing accurate free-energy calculations from large-scale coarse-grained computer simulations, we found that the membrane mediates the interaction among protein filaments as a combination of short- and long-ranged interactions. The long-ranged component acts at strikingly long distances, giving rise to a variety of micron-sized ordered patterns. This mechanism may contribute to the long-ranged spatiotemporal control of membrane remodeling by proteins in the cell.
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Affiliation(s)
- Mijo Simunovic
- Department
of Chemistry, Institute for Biophysical Dynamics, and James Franck
Institute, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States
| | - Anđela Šarić
- Department
of Physics and Astronomy, Institute for the Physics of Living Systems, University College London, Gower Street, London, WC1E 6BT, U.K.
| | - J. Michael Henderson
- Department
of Chemistry, Institute for Biophysical Dynamics, and James Franck
Institute, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States
| | - Ka Yee C. Lee
- Department
of Chemistry, Institute for Biophysical Dynamics, and James Franck
Institute, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States
| | - Gregory A. Voth
- Department
of Chemistry, Institute for Biophysical Dynamics, and James Franck
Institute, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States
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8
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Li J, Barylko B, Eichorst JP, Mueller JD, Albanesi JP, Chen Y. Association of Endophilin B1 with Cytoplasmic Vesicles. Biophys J 2017; 111:565-576. [PMID: 27508440 DOI: 10.1016/j.bpj.2016.06.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 06/14/2016] [Accepted: 06/16/2016] [Indexed: 01/21/2023] Open
Abstract
Endophilins are SH3- and BAR domain-containing proteins implicated in membrane remodeling and vesicle formation. Endophilins A1 and A2 promote the budding of endocytic vesicles from the plasma membrane, whereas endophilin B1 has been implicated in vesicle budding from intracellular organelles, including the trans-Golgi network and late endosomes. We previously reported that endophilins A1 and A2 exist almost exclusively as soluble dimers in the cytosol. Here, we present results of fluorescence fluctuation spectroscopy analyses indicating that, in contrast, the majority of endophilin B1 is present in multiple copies on small, highly mobile cytoplasmic vesicles. Formation of these vesicles was enhanced by overexpression of wild-type dynamin 2, but suppressed by expression of a catalytically inactive dynamin 2 mutant. Using dual-color heterospecies partition analysis, we identified the epidermal growth factor receptor on endophilin B1 vesicles. Moreover, a proportion of endophilin B1 vesicles also contained caveolin, whereas clathrin was almost undetectable on those vesicles. These results raise the possibility that endophilin B1 participates in dynamin 2-dependent formation of a population of transport vesicles distinct from those generated by A-type endophilins.
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Affiliation(s)
- Jinhui Li
- Department of Physics, University of Minnesota, Minneapolis, Minnesota
| | | | - John P Eichorst
- Department of Physics, University of Minnesota, Minneapolis, Minnesota
| | - Joachim D Mueller
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota
| | | | - Yan Chen
- Department of Physics, University of Minnesota, Minneapolis, Minnesota.
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9
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Advances on the Transfer of Lipids by Lipid Transfer Proteins. Trends Biochem Sci 2017; 42:516-530. [PMID: 28579073 PMCID: PMC5486777 DOI: 10.1016/j.tibs.2017.05.001] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 05/02/2017] [Accepted: 05/03/2017] [Indexed: 12/22/2022]
Abstract
Transfer of lipid across the cytoplasm is an essential process for intracellular lipid traffic. Lipid transfer proteins (LTPs) are defined by highly controlled in vitro experiments. The functional relevance of these is supported by evidence for the same reactions inside cells. Major advances in the LTP field have come from structural bioinformatics identifying new LTPs, and from the development of countercurrent models for LTPs. However, the ultimate aim is to unite in vitro and in vivo data, and this is where much progress remains to be made. Even where in vitro and in vivo experiments align, rates of transfer tend not to match. Here we set out some of the advances that might test how LTPs work. LTPs facilitate the essential movement of lipid across aqueous spaces and are defined by in vitro experiments. Recent developments include a novel concept of countercurrent lipid transfer and identification of additional LTP families by bioinformatics. In vivo and in vitro data have yet to converge to one complete model. Advances in in vitro characterisation of LTPs provide an opportunity to unite biochemical experimentation to cellular function.
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10
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Poudel KR, Dong Y, Yu H, Su A, Ho T, Liu Y, Schulten K, Bai J. A time course of orchestrated endophilin action in sensing, bending, and stabilizing curved membranes. Mol Biol Cell 2016; 27:2119-32. [PMID: 27170174 PMCID: PMC4927284 DOI: 10.1091/mbc.e16-04-0264] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 05/06/2016] [Indexed: 11/11/2022] Open
Abstract
Endophilin is a founding member of the membrane-bending protein family. It promotes rapid endocytosis on a milliseconds-to-seconds time scale. The short duration of rapid endocytosis requires endophilin to act quickly. High-resolution kinetic measurements show the sequential action that endophilin takes to quickly deform membranes. Numerous proteins act in concert to sculpt membrane compartments for cell signaling and metabolism. These proteins may act as curvature sensors, membrane benders, and scaffolding molecules. Here we show that endophilin, a critical protein for rapid endocytosis, quickly transforms from a curvature sensor into an active bender upon membrane association. We find that local membrane deformation does not occur until endophilin inserts its amphipathic helices into lipid bilayers, supporting an active bending mechanism through wedging. Our time-course studies show that endophilin continues to drive membrane changes on a seconds-to-minutes time scale, indicating that the duration of endocytosis events constrains the mode of endophilin action. Finally, we find a requirement of coordinated activities between wedging and scaffolding for endophilin to produce stable membrane tubules in vitro and to promote synaptic activity in vivo. Together these data demonstrate that endophilin is a multifaceted molecule that precisely integrates activities of sensing, bending, and stabilizing curvature to sculpt membranes with speed.
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Affiliation(s)
- Kumud R Poudel
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109 Department of Biochemistry, University of Washington, Seattle, WA 98195
| | - Yongming Dong
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109 Department of Biochemistry, University of Washington, Seattle, WA 98195
| | - Hang Yu
- Beckman Institute, University of Illinois, Urbana, IL 61801
| | - Allen Su
- Department of Biochemistry, University of Washington, Seattle, WA 98195
| | - Thuong Ho
- Department of Biochemistry, University of Washington, Seattle, WA 98195
| | - Yan Liu
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109 Department of Biochemistry, University of Washington, Seattle, WA 98195
| | - Klaus Schulten
- Beckman Institute, University of Illinois, Urbana, IL 61801 Department of Physics, University of Illinois, Urbana, IL 61801
| | - Jihong Bai
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109 Department of Biochemistry, University of Washington, Seattle, WA 98195
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11
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Gupta R, Ghosh S. Bax and Bif-1 proteins interact on Bilayer Lipid Membrane and form pore. Biochem Biophys Res Commun 2015; 463:751-5. [DOI: 10.1016/j.bbrc.2015.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 06/02/2015] [Indexed: 10/23/2022]
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12
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Capraro BR, Shi Z, Wu T, Chen Z, Dunn JM, Rhoades E, Baumgart T. Kinetics of endophilin N-BAR domain dimerization and membrane interactions. J Biol Chem 2013; 288:12533-43. [PMID: 23482561 DOI: 10.1074/jbc.m112.435511] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The recruitment to plasma membrane invaginations of the protein endophilin is a temporally regulated step in clathrin-mediated endocytosis. Endophilin is believed to sense or stabilize membrane curvature, which in turn likely depends on the dimeric structure of the protein. The dynamic nature of the membrane association and dimerization of endophilin is thus functionally important and is illuminated herein. Using subunit exchange Förster resonance energy transfer (FRET), we determine dimer dissociation kinetics and find a dimerization equilibrium constant orders of magnitude lower than previously published values. We characterize N-BAR domain membrane association kinetics under conditions where the dimeric species predominates, by stopped flow, observing prominent electrostatic sensitivity of membrane interaction kinetics. Relative to membrane binding, we find that protein monomer/dimer species equilibrate with far slower kinetics. Complementary optical microscopy studies reveal strikingly slow membrane dissociation and an increase of dissociation rate constant for a construct lacking the amphipathic segment helix 0 (H0). We attribute the slow dissociation kinetics to higher-order protein oligomerization on the membrane. We incorporate our findings into a kinetic scheme for endophilin N-BAR membrane binding and find a significant separation of time scales for endophilin membrane binding and subsequent oligomerization. This separation may facilitate the regulation of membrane trafficking phenomena.
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Affiliation(s)
- Benjamin R Capraro
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Membrane curvature and its generation by BAR proteins. Trends Biochem Sci 2012; 37:526-33. [PMID: 23058040 DOI: 10.1016/j.tibs.2012.09.001] [Citation(s) in RCA: 190] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 09/12/2012] [Accepted: 09/13/2012] [Indexed: 01/26/2023]
Abstract
Membranes are flexible barriers that surround the cell and its compartments. To execute vital functions such as locomotion or receptor turnover, cells need to control the shapes of their membranes. In part, this control is achieved through membrane-bending proteins, such as the Bin/amphiphysin/Rvs (BAR) domain proteins. Many open questions remain about the mechanisms by which membrane-bending proteins function. Addressing this shortfall, recent structures of BAR protein:membrane complexes support existing mechanistic models, but also produced novel insights into how BAR domain proteins sense, stabilize, and generate curvature. Here we review these recent findings, focusing on how BAR proteins interact with the membrane, and how the resulting scaffold structures might aid the recruitment of other proteins to the sites where membranes are bent.
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Sun S, Suresh S, Liu H, Tepp WH, Johnson EA, Edwardson JM, Chapman ER. Receptor binding enables botulinum neurotoxin B to sense low pH for translocation channel assembly. Cell Host Microbe 2012; 10:237-47. [PMID: 21925111 DOI: 10.1016/j.chom.2011.06.012] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 06/21/2011] [Accepted: 06/21/2011] [Indexed: 12/21/2022]
Abstract
Botulinum neurotoxins (BoNTs, serotypes A-G), elaborated by Clostridium botulinum, can induce lethal paralysis and are classified as Category A bioterrorism agents. However, how BoNTs translocate from endosomes into the cytosol of neurons to gain access to their intracellular targets remains enigmatic. We discovered that binding to the ganglioside GT1b, a toxin coreceptor, enables BoNT/B to sense low pH, undergo a significant change in secondary structure, and transform into a hydrophobic oligomeric membrane protein. Imaging of the toxin on lipid bilayers using atomic force microscopy revealed donut-shaped channel-like structures that resemble other protein translocation assemblies. Toosendanin, a drug with therapeutic effects against botulism, inhibited GT1b-dependent BoNT/B oligomerization and in parallel truncated BoNT/B single-channel conductance, suggesting that oligomerization plays a role in the translocation reaction. Thus, BoNT/B functions as a coincidence detector for receptor and low pH to ensure spatial and temporal accuracy for toxin conversion into a translocation channel.
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Affiliation(s)
- Shihu Sun
- Howard Hughes Medical Institute, USA
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Interplay between VGLUT isoforms and endophilin A1 regulates neurotransmitter release and short-term plasticity. Neuron 2011; 69:1147-59. [PMID: 21435559 DOI: 10.1016/j.neuron.2011.02.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2011] [Indexed: 12/13/2022]
Abstract
Vesicular glutamate transporters (VGLUTs) are essential for filling synaptic vesicles with glutamate and mammals express three VGLUT isoforms (VGLUT1-3) with distinct spatiotemporal expression patterns. Here, we find that neurons expressing VGLUT1 have lower release probability and less short-term depression than neurons expressing VGLUT2 or VGLUT3. Investigation of the underlying mechanism identified endophilin A1 as a positive regulator of exocytosis whose expression levels are positively correlated with release efficiency and showed that the differences in release efficiency between VGLUT1- and VGLUT2-expressing neurons are due to VGLUT1's ability to bind endophilin A1 and inhibit endophilin-induced enhancement of release probability.
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