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Abstract
Atlastins are mechanochemical GTPases that catalyze homotypic fusion of ER tubules. Recent work has demonstrated that tethering and fusion by the three mammalian atlastin paralogs are differentially regulated by their variable N- and C-terminal extensions. These new findings have profound implications for atlastin-mediated homeostasis of the tubular ER network.
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Affiliation(s)
- Shivaani Krishna
- Bay Area Institute of Science, Altos Labs Inc., Redwood City, CA, USA
| | - Marijn G.J. Ford
- Bay Area Institute of Science, Altos Labs Inc., Redwood City, CA, USA
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Jang E, Moon Y, Yoon SY, Diaz JAR, Lee M, Ko N, Park J, Eom SH, Lee C, Jun Y. Human atlastins are sufficient to drive the fusion of liposomes with a physiological lipid composition. J Cell Biol 2023; 222:e202109090. [PMID: 36757370 PMCID: PMC9949273 DOI: 10.1083/jcb.202109090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 10/20/2022] [Accepted: 01/17/2023] [Indexed: 02/10/2023] Open
Abstract
The dynamin-like GTPase atlastin is believed to be the minimal machinery required for homotypic endoplasmic reticulum (ER) membrane fusion, mainly because Drosophila atlastin is sufficient to drive liposome fusion. However, it remains unclear whether mammalian atlastins, including the three human atlastins, are sufficient to induce liposome fusion, raising doubts about their major roles in mammalian cells. Here, we show that all human atlastins are sufficient to induce fusion when reconstituted into liposomes with a lipid composition mimicking that of the ER. Although the fusogenic activity of ATL1, which is predominantly expressed in neuronal cells, was weaker than that of ATL2 or ATL3, the addition of M1-spastin, a neuron-specific factor, markedly increased ATL1-mediated liposome fusion. Although we observed efficient fusion between ER microsomes isolated from cultured, non-neuronal cells that predominantly express ATL2-1, an autoinhibited isoform of ATL2, ATL2-1 failed to support liposome fusion by itself as reported previously, indicating that cellular factors enable ATL2-1 to mediate ER fusion in vivo.
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Affiliation(s)
- Eunhong Jang
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Yeojin Moon
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - So Young Yoon
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Joyce Anne R. Diaz
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Miriam Lee
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Naho Ko
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Jongseo Park
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Soo Hyun Eom
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Changwook Lee
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Youngsoo Jun
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
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Joardar A, Pattnaik GP, Chakraborty H. Mechanism of Membrane Fusion: Interplay of Lipid and Peptide. J Membr Biol 2022; 255:211-224. [PMID: 35435451 PMCID: PMC9014786 DOI: 10.1007/s00232-022-00233-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 03/25/2022] [Indexed: 11/26/2022]
Abstract
Membrane fusion is an essential process for the survival of eukaryotes and the entry of enveloped viruses into host cells. A proper understanding of the mechanism of membrane fusion would provide us a handle to manipulate several biological pathways, and design efficient vaccines against emerging and re-emerging viral infections. Although fusion proteins take the central stage in catalyzing the process, role of lipid composition is also of paramount importance. Lipid composition modulates membrane organization and dynamics and impacts the lipid–protein (peptide) interaction. Moreover, the intrinsic curvature of lipids has strong impact on the formation of stalk and hemifusion diaphragm. Detection of transiently stable intermediates remains the bottleneck in the understanding of fusion mechanism. In order to circumvent this challenge, analytical methods can be employed to determine the kinetic parameters from ensemble average measurements of observables, such as lipid mixing, content mixing, and content leakage. The current review aims to present an analytical method that would aid our understanding of the fusion mechanism, provides a better insight into the role of lipid shape, and discusses the interplay of lipid and peptide in membrane fusion.
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Affiliation(s)
- Ankita Joardar
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha, 768019, India
| | | | - Hirak Chakraborty
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha, 768019, India.
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Katic A, Hüsler D, Letourneur F, Hilbi H. Dictyostelium Dynamin Superfamily GTPases Implicated in Vesicle Trafficking and Host-Pathogen Interactions. Front Cell Dev Biol 2021; 9:731964. [PMID: 34746129 PMCID: PMC8565484 DOI: 10.3389/fcell.2021.731964] [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: 06/28/2021] [Accepted: 09/14/2021] [Indexed: 11/21/2022] Open
Abstract
The haploid social amoeba Dictyostelium discoideum is a powerful model organism to study vesicle trafficking, motility and migration, cell division, developmental processes, and host cell-pathogen interactions. Dynamin superfamily proteins (DSPs) are large GTPases, which promote membrane fission and fusion, as well as membrane-independent cellular processes. Accordingly, DSPs play crucial roles for vesicle biogenesis and transport, organelle homeostasis, cytokinesis and cell-autonomous immunity. Major progress has been made over the last years in elucidating the function and structure of mammalian DSPs. D. discoideum produces at least eight DSPs, which are involved in membrane dynamics and other processes. The function and structure of these large GTPases has not been fully explored, despite the elaborate genetic and cell biological tools available for D. discoideum. In this review, we focus on the current knowledge about mammalian and D. discoideum DSPs, and we advocate the use of the genetically tractable amoeba to further study the role of DSPs in cell and infection biology. Particular emphasis is put on the virulence mechanisms of the facultative intracellular bacterium Legionella pneumophila.
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Affiliation(s)
- Ana Katic
- Institute of Medical Microbiology, University of Zürich, Zurich, Switzerland
| | - Dario Hüsler
- Institute of Medical Microbiology, University of Zürich, Zurich, Switzerland
| | - François Letourneur
- Laboratory of Pathogen Host Interactions, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Hubert Hilbi
- Institute of Medical Microbiology, University of Zürich, Zurich, Switzerland
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