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Park K, Ju S, Choi H, Gao P, Bang G, Choi JH, Jang J, Morris AJ, Kang BH, Hsu VW, Park SY. PITPβ promotes COPI vesicle fission through lipid transfer and membrane contact formation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.27.596058. [PMID: 38853868 PMCID: PMC11160616 DOI: 10.1101/2024.05.27.596058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Lipid transfer through membrane contact has been implicated to support vesicular transport, but a mechanistic understanding of this process remains to be achieved. Here, examining Coat Protein I (COPI) transport, we find that phosphatidylcholine (PC) with short acyl chains (sPC), which is needed to support COPI vesicle fission, is delivered through membrane contact from the endoplasmic reticulum (ER) to the Golgi complex at sites of COPI vesicle formation. Phosphatidylinositol transfer protein beta (PITPβ) plays a central role in this delivery by not only catalyzing PC transfer, but also forming membrane contact. By combining cell-based studies with reconstitution approaches, we achieve spatial and temporal detail in explaining how sPC delivery occurs. Our findings advance the mechanistic understanding of how membrane contact is needed for vesicular transport in a model pathway and shed new insights into how PITPβ acts.
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Affiliation(s)
- Kunyou Park
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women’s Hospital, and Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Sungeun Ju
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Hyewon Choi
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Peng Gao
- School of Life Sciences, State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Geul Bang
- Research Center for Bioconvergence Analysis, Korea Basic Science Institute, Cheongju, Republic of Korea
| | - Jung Hoon Choi
- Department of Bio-Chemical Analysis, Korea Basic Science Institute, Cheongju, Republic of Korea
| | - Jiwon Jang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Andrew J. Morris
- University of Arkansas for Medical Sciences and Central Arkansas Veterans Affairs Healthcare System, Little Rock, AR 72205, USA
| | - Byung-Ho Kang
- School of Life Sciences, State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Victor W. Hsu
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women’s Hospital, and Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Seung-Yeol Park
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
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2
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Zhou H, Huo Y, Yang N, Wei T. Phosphatidic acid: from biophysical properties to diverse functions. FEBS J 2024; 291:1870-1885. [PMID: 37103336 DOI: 10.1111/febs.16809] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 03/15/2023] [Accepted: 04/26/2023] [Indexed: 04/28/2023]
Abstract
Phosphatidic acid (PA), the simplest phospholipid, acts as a key metabolic intermediate and second messenger that impacts diverse cellular and physiological processes across species ranging from microbes to plants and mammals. The cellular levels of PA dynamically change in response to stimuli, and multiple enzymatic reactions can mediate its production and degradation. PA acts as a signalling molecule and regulates various cellular processes via its effects on membrane tethering, enzymatic activities of target proteins, and vesicular trafficking. Because of its unique physicochemical properties compared to other phospholipids, PA has emerged as a class of new lipid mediators influencing membrane structure, dynamics, and protein interactions. This review summarizes the biosynthesis, dynamics, and cellular functions and properties of PA.
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Affiliation(s)
- Hejiang Zhou
- College of Food Science and Technology, Yunnan Agricultural University, Kunming, China
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yanwu Huo
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Na Yang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- Laboratory of Genetic and Genomics, National Institute on Aging, NIH, Baltimore, MD, USA
| | - Taotao Wei
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
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3
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Chu SL, Huang JR, Chang YT, Yao SY, Yang JS, Hsu VW, Hsu JW. Phosphoglycerate kinase 1 acts as a cargo adaptor to promote EGFR transport to the lysosome. Nat Commun 2024; 15:1021. [PMID: 38310114 PMCID: PMC10838266 DOI: 10.1038/s41467-024-45443-4] [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: 11/12/2022] [Accepted: 01/23/2024] [Indexed: 02/05/2024] Open
Abstract
The epidermal growth factor receptor (EGFR) plays important roles in multiple cellular events, including growth, differentiation, and motility. A major mechanism of downregulating EGFR function involves its endocytic transport to the lysosome. Sorting of proteins into intracellular pathways involves cargo adaptors recognizing sorting signals on cargo proteins. A dileucine-based sorting signal has been identified previously for the sorting of endosomal EGFR to the lysosome, but a cargo adaptor that recognizes this signal remains unknown. Here, we find that phosphoglycerate kinase 1 (PGK1) is recruited to endosomal membrane upon its phosphorylation, where it binds to the dileucine sorting signal in EGFR to promote the lysosomal transport of this receptor. We also elucidate two mechanisms that act in concert to promote PGK1 recruitment to endosomal membrane, a lipid-based mechanism that involves phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and a protein-based mechanism that involves hepatocyte growth factor receptor substrate (Hrs). These findings reveal an unexpected function for a metabolic enzyme and advance the mechanistic understanding of how EGFR is transported to the lysosome.
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Affiliation(s)
- Shao-Ling Chu
- Institute of Biochemical Sciences, National Taiwan University, Taipei, 10617, Taiwan
| | - Jia-Rong Huang
- Institute of Biochemical Sciences, National Taiwan University, Taipei, 10617, Taiwan
| | - Yu-Tzu Chang
- Institute of Biochemical Sciences, National Taiwan University, Taipei, 10617, Taiwan
| | - Shu-Yun Yao
- Institute of Biochemical Sciences, National Taiwan University, Taipei, 10617, Taiwan
| | - Jia-Shu Yang
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital, and Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
| | - Victor W Hsu
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital, and Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA.
| | - Jia-Wei Hsu
- Institute of Biochemical Sciences, National Taiwan University, Taipei, 10617, Taiwan.
- Institute of Biological Chemistry, Academia Sinica, Taipei, 11529, Taiwan.
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4
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Liu L, Duan C, Wang R. Kinetic pathway and micromechanics of fusion/fission for polyelectrolyte vesicles. J Chem Phys 2024; 160:024908. [PMID: 38214388 DOI: 10.1063/5.0185934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 12/26/2023] [Indexed: 01/13/2024] Open
Abstract
Despite the wide existence of vesicles in living cells as well as their important applications like drug delivery, the underlying mechanism of vesicle fusion/fission remains under debate. Classical models cannot fully explain recent observations in experiments and simulations. Here, we develop a constrained self-consistent field theory that allows tracking the shape evolution and free energy as a function of center-of-mass separation distance. Fusion and fission are described in a unified framework. Both the kinetic pathway and the mechanical response can be simultaneously captured. By taking vesicles formed by polyelectrolytes as a model system, we predict discontinuous transitions between the three morphologies: parent vesicle with a single cavity, hemifission/hemifusion, and two separated child vesicles, as a result of breaking topological isomorphism. With the increase in inter-vesicle repulsion, we observe a great reduction in the cleavage energy, indicating that vesicle fission can be achieved without hemifission, in good agreement with simulation results. The force-extension relationship elucidates typical plasticity for separating two vesicles. The super extensibility in the mechanical response of vesicle is in stark contrast to soft particles with other morphologies, such as cylinder and sphere. Our work elucidates the fundamental physical chemistry based on intrinsic topological features of vesicle fusion/fission, which provides insights into various phenomena observed in experiments and simulations.
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Affiliation(s)
- Luofu Liu
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA
| | - Chao Duan
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA
| | - Rui Wang
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, USA
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5
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Pang X, Zhang Y, Park K, Liao Z, Li J, Xu J, Hong MT, Yin G, Zhang T, Wang Y, Egelman EH, Fan J, Park SY, Hsu VW, Sun F. Structural elucidation of how ARF small GTPases induce membrane tubulation for vesicle fission. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.19.572083. [PMID: 38187566 PMCID: PMC10769218 DOI: 10.1101/2023.12.19.572083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
The ADP-Ribosylation Factor (ARF) small GTPases have been found to act in vesicle fission through a direct ability to tubulate membrane. Here, we have used cryo-electron microscopy (EM) to solve the structure of an ARF6 protein lattice assembled on tubulated membrane to 3.9 Å resolution. ARF6 forms tetramers that polymerize into helical arrays to form this lattice. We identify, and confirm functionally, protein contacts critical for this lattice formation. The solved structure also suggests how the ARF amphipathic helix is positioned in the lattice for membrane insertion, and how a GTPase-activating protein (GAP) docks onto the lattice to catalyze ARF-GTP hydrolysis in completing membrane fission. As ARF1 and ARF6 are structurally conserved, we have also modeled ARF1 onto the ARF6 lattice, which has allowed us to pursue the reconstitution of Coat Protein I (COPI) vesicles to confirm more definitively that the ARF lattice acts in vesicle fission. Our findings are notable for having achieved the first detailed glimpse of how a small GTPase bends membrane and having provided a molecular understanding of how an ARF protein acts in vesicle fission.
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Affiliation(s)
- Xiaoyun Pang
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- Equal contribution
| | - Yan Zhang
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- Equal contribution
| | - Kunyou Park
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
- Equal contribution
| | - Zhenyu Liao
- City University of Hong Kong, Hong Kong, China
| | - Jian Li
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital, and Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
| | - Jiashu Xu
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- School of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Minh-Triet Hong
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Guoliang Yin
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- School of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tongming Zhang
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yaoyu Wang
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia, VA 22908 USA
| | - Jun Fan
- City University of Hong Kong, Hong Kong, China
| | - Seung-Yeol Park
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Victor W Hsu
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital, and Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
| | - Fei Sun
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- School of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Center for Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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Choi H, Park K, Hsu VW, Park SY. Studying the Role of Lipid Geometry in COPI Vesicle Formation. Methods Mol Biol 2022; 2557:519-528. [PMID: 36512234 DOI: 10.1007/978-1-0716-2639-9_30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The Coat Protein I (COPI) complex forms vesicles from Golgi membrane for retrograde transport among the Golgi stacks, and also from the Golgi to the endoplasmic reticulum (ER). We have been elucidating the mechanistic details of COPI vesicle formation through a reconstitution system that involves the incubation of Golgi membrane with purified components. This approach has enabled us recently to gain new insight into how certain lipids are critical for the fission stage of COPI vesicle formation. Lipid geometry has been proposed to act in the formation of transport carriers by promoting membrane curvature. However, evidence for this role has come from studies using simplified membranes, while confirmation in the more physiologic setting of native membranes has been challenging, as such membranes contain a complex composition of lipids and proteins. We have recently refined the COPI reconstitution system to overcome this experimental obstacle. This has led us to identify an unanticipated type of lipid geometry needed for COPI vesicle fission. This chapter describes the approach that we have developed to enable this discovery. The methodologies include: (i) preparation Golgi membrane from cells that are deficient in a particular lipid enzyme activity and (ii) functional rescue of this deficiency by introducing the product of the lipid enzyme, with experiments being performed at the in vitro level to gain mechanistic clarity and at the in vivo level to confirm physiologic relevance.
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Affiliation(s)
- Hyewon Choi
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Republic of Korea
| | - Kunyou Park
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Republic of Korea
| | - Victor W Hsu
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital, Boston, MA, USA. .,Department of Medicine, Harvard Medical School, Boston, MA, USA.
| | - Seung-Yeol Park
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Republic of Korea.
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Lipid Dyshomeostasis and Inherited Cerebellar Ataxia. Mol Neurobiol 2022; 59:3800-3828. [PMID: 35420383 PMCID: PMC9148275 DOI: 10.1007/s12035-022-02826-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 04/01/2022] [Indexed: 12/04/2022]
Abstract
Cerebellar ataxia is a form of ataxia that originates from dysfunction of the cerebellum, but may involve additional neurological tissues. Its clinical symptoms are mainly characterized by the absence of voluntary muscle coordination and loss of control of movement with varying manifestations due to differences in severity, in the site of cerebellar damage and in the involvement of extracerebellar tissues. Cerebellar ataxia may be sporadic, acquired, and hereditary. Hereditary ataxia accounts for the majority of cases. Hereditary ataxia has been tentatively divided into several subtypes by scientists in the field, and nearly all of them remain incurable. This is mainly because the detailed mechanisms of these cerebellar disorders are incompletely understood. To precisely diagnose and treat these diseases, studies on their molecular mechanisms have been conducted extensively in the past. Accumulating evidence has demonstrated that some common pathogenic mechanisms exist within each subtype of inherited ataxia. However, no reports have indicated whether there is a common mechanism among the different subtypes of inherited cerebellar ataxia. In this review, we summarize the available references and databases on neurological disorders characterized by cerebellar ataxia and show that a subset of genes involved in lipid homeostasis form a new group that may cause ataxic disorders through a common mechanism. This common signaling pathway can provide a valuable reference for future diagnosis and treatment of ataxic disorders.
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Abstract
The Golgi complex plays a central role in protein secretion by regulating cargo sorting and trafficking. As these processes are of functional importance to cell polarity, motility, growth, and division, there is considerable interest in achieving a comprehensive understanding of Golgi complex biology. However, the unique stack structure of this organelle has been a major hurdle to our understanding of how proteins are secreted through the Golgi apparatus. Herein, we summarize available relevant research to gain an understanding of protein secretion via the Golgi complex. This includes the molecular mechanisms of intra-Golgi trafficking and cargo export in the trans-Golgi network. Moreover, we review recent insights on signaling pathways regulated by the Golgi complex and their physiological significance.
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Affiliation(s)
- Kunyou Park
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Sungeun Ju
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Nari Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Seung-Yeol Park
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Korea
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Tokuoka SM, Kita Y, Sato M, Shimizu T, Yatomi Y, Oda Y. Development of Tandem Mass Tag Labeling Method for Lipid Molecules Containing Carboxy and Phosphate Groups, and Their Stability in Human Serum. Metabolites 2020; 11:metabo11010019. [PMID: 33396791 PMCID: PMC7824108 DOI: 10.3390/metabo11010019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/21/2020] [Accepted: 12/28/2020] [Indexed: 12/26/2022] Open
Abstract
In clinical lipidomics, it is a challenge to measure a large number of samples and to reproduce the quantitative results. We expanded the range of application of the tandem mass tag (TMT) method, which is widely used in proteomics, to lipidomic fields. There are various types of lipid molecule, for example, eicosanoids have a carboxyl group and phosphatidic acid has a phosphate group. We modified these functional groups simultaneously with TMT. This approach allows for a single analysis by mixing six samples and using one of the six samples as a bridging sample; the quantitative data can be easily normalized even if the number of measurements increases. To accommodate a large number of samples, we utilize a pooled serum sample of 300 individuals as a bridging sample. The stability of these lipid molecules in serum was examined as an analytical validation for the simultaneous TMT labeling. It was found that the stability of these lipid molecules in serum differs greatly depending on the lipid species. These findings reaffirmed the importance of proper sample preparation and storage to obtain reliable data. The TMT labeling method is expected to be a useful method for lipidomics with high-throughput and reliable reproducibility.
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Affiliation(s)
- Suzumi M. Tokuoka
- Department of Lipidomics, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8654, Japan; (S.M.T.); (Y.K.); (T.S.)
| | - Yoshihiro Kita
- Department of Lipidomics, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8654, Japan; (S.M.T.); (Y.K.); (T.S.)
| | - Masaya Sato
- Department of Clinical Laboratory Medicine, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8654, Japan; (M.S.); (Y.Y.)
| | - Takao Shimizu
- Department of Lipidomics, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8654, Japan; (S.M.T.); (Y.K.); (T.S.)
- Department of Lipid Signaling, National Center for Global Health and Medicine, Toyama 1-21-1, Shinjuku-ku, Tokyo 162-8655, Japan
| | - Yutaka Yatomi
- Department of Clinical Laboratory Medicine, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8654, Japan; (M.S.); (Y.Y.)
| | - Yoshiya Oda
- Department of Lipidomics, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8654, Japan; (S.M.T.); (Y.K.); (T.S.)
- Correspondence: ; Tel.: +81-3-5841-3540
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The roles of the diversity of amphipathic lipids in shaping membranes by membrane-shaping proteins. Biochem Soc Trans 2020; 48:837-851. [PMID: 32597479 DOI: 10.1042/bst20190376] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 06/02/2020] [Accepted: 06/05/2020] [Indexed: 12/23/2022]
Abstract
Lipid compositions of cells differ according to cell types and intracellular organelles. Phospholipids are major cell membrane lipids and have hydrophilic head groups and hydrophobic fatty acid tails. The cellular lipid membrane without any protein adapts to spherical shapes, and protein binding to the membrane is thought to be required for shaping the membrane for various cellular events. Until recently, modulation of cellular lipid membranes was initially shown to be mediated by proteins recognizing lipid head groups, including the negatively charged ones of phosphatidylserine and phosphoinositides. Recent studies have shown that the abilities of membrane-deforming proteins are also regulated by the composition of fatty acid tails, which cause different degrees of packing defects. The binding of proteins to cellular lipid membranes is affected by the packing defects, presumably through modulation of their interactions with hydrophobic amino acid residues. Therefore, lipid composition can be characterized by both packing defects and charge density. The lipid composition regarding fatty acid tails affects membrane bending via the proteins with amphipathic helices, including those with the ArfGAP1 lipid packing sensor (ALPS) motif and via membrane-deforming proteins with structural folding, including those with the Bin-Amphiphysin-Rvs167 (BAR) domains. This review focuses on how the fatty acid tails, in combination with the head groups of phospholipids, affect protein-mediated membrane deformation.
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11
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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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