1
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Nguyen HNA, Sharp L, Lyman E, Saenz JP. Varying the position of phospholipid acyl chain unsaturation modulates hopanoid and sterol ordering. Biophys J 2024; 123:1896-1902. [PMID: 38850024 DOI: 10.1016/j.bpj.2024.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 05/31/2024] [Accepted: 06/04/2024] [Indexed: 06/09/2024] Open
Abstract
The cell membrane must balance mechanical stability with fluidity to function as both a barrier and an organizational platform. Key to this balance is the ordering of hydrocarbon chains and the packing of lipids. Many eukaryotes synthesize sterols, which are uniquely capable of modulating the lipid order to decouple membrane stability from fluidity. Ancient sterol analogs known as hopanoids are found in many bacteria and proposed as ancestral ordering lipids. The juxtaposition of sterols and hopanoids in extant organisms prompts us to ask why both pathways persist, especially in light of their convergent ability to order lipids. In this work, simulations, monolayer experiments, and cellular assays show that hopanoids and sterols order unsaturated phospholipids differently based on the position of double bonds in the phospholipid acyl chain. We find that cholesterol and diplopterol's methyl group distributions lead to distinct effects on unsaturated lipids. In Mesoplasma florum, diplopterol's constrained ordering capacity reduces membrane resistance to osmotic stress, unlike cholesterol. These findings suggest that cholesterol's broader lipid-ordering ability may have facilitated the exploration of a more diverse lipidomic landscape in eukaryotic membranes.
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Affiliation(s)
- Ha-Ngoc-Anh Nguyen
- Technische Universität Dresden, B CUBE Center for Molecular Bioengineering, Dresden, Germany
| | - Liam Sharp
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware; College of Arts and Sciences, Fairfield University, Fairfield, Connecticut
| | - Edward Lyman
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware; Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware
| | - James P Saenz
- Technische Universität Dresden, B CUBE Center for Molecular Bioengineering, Dresden, Germany; Medical Faculty, Technische Universität Dresden, Dresden, Germany.
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2
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Barbotin A, Billaudeau C, Sezgin E, Carballido-López R. Quantification of membrane fluidity in bacteria using TIR-FCS. Biophys J 2024:S0006-3495(24)00407-7. [PMID: 38877702 DOI: 10.1016/j.bpj.2024.06.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 05/28/2024] [Accepted: 06/10/2024] [Indexed: 06/16/2024] Open
Abstract
Plasma membrane fluidity is an important phenotypic feature that regulates the diffusion, function, and folding of transmembrane and membrane-associated proteins. In bacterial cells, variations in membrane fluidity are known to affect respiration, transport, and antibiotic resistance. Membrane fluidity must therefore be tightly regulated to adapt to environmental variations and stresses such as temperature fluctuations or osmotic shocks. Quantitative investigation of bacterial membrane fluidity has been, however, limited due to the lack of available tools, primarily due to the small size and membrane curvature of bacteria that preclude most conventional analysis methods used in eukaryotes. Here, we develop an assay based on total internal reflection-fluorescence correlation spectroscopy (TIR-FCS) to directly measure membrane fluidity in live bacteria via the diffusivity of fluorescent membrane markers. With simulations validated by experiments, we could determine how the small size, high curvature, and geometry of bacteria affect diffusion measurements and correct subsequent measurements for unbiased diffusion coefficient estimation. We used this assay to quantify the fluidity of the cytoplasmic membranes of the Gram-positive bacteria Bacillus subtilis (rod-shaped) and Staphylococcus aureus (coccus) at high (37°C) and low (20°C) temperatures in a steady state and in response to a cold shock, caused by a shift from high to low temperature. The steady-state fluidity was lower at 20°C than at 37°C, yet differed between B. subtilis and S. aureus at 37°C. Upon cold shock, the membrane fluidity decreased further below the steady-state fluidity at 20°C and recovered within 30 min in both bacterial species. Our minimally invasive assay opens up exciting perspectives for the study of a wide range of phenomena affecting the bacterial membrane, from disruption by chemicals or antibiotics to viral infection or change in nutrient availability.
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Affiliation(s)
- Aurélien Barbotin
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France.
| | - Cyrille Billaudeau
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Erdinc Sezgin
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden
| | - Rut Carballido-López
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France.
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3
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Bahammou D, Recorbet G, Mamode Cassim A, Robert F, Balliau T, Van Delft P, Haddad Y, Mongrand S, Fouillen L, Simon-Plas F. A combined lipidomic and proteomic profiling of Arabidopsis thaliana plasma membrane. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024. [PMID: 38761101 DOI: 10.1111/tpj.16810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 04/24/2024] [Accepted: 04/30/2024] [Indexed: 05/20/2024]
Abstract
The plant plasma membrane (PM) plays a key role in perception of environmental signals, and set-up of adaptive responses. An exhaustive and quantitative description of the whole set of lipids and proteins constituting the PM is necessary to understand how these components allow to fulfill such essential physiological functions. Here we provide by state-of-the-art approaches the first combined reference of the plant PM lipidome and proteome from Arabidopsis thaliana suspension cell culture. We identified and quantified a reproducible core set of 2165 proteins, which is by far the largest set of available data concerning this plant PM proteome. Using the same samples, combined lipidomic approaches, allowing the identification and quantification of an unprecedented repertoire of 414 molecular species of lipids showed that sterols, phospholipids, and sphingolipids are present in similar proportions in the plant PM. Within each lipid class, the precise amount of each lipid family and the relative proportion of each molecular species were further determined, allowing to establish the complete lipidome of Arabidopsis PM, and highlighting specific characteristics of the different molecular species of lipids. Results obtained point to a finely tuned adjustment of the molecular characteristics of lipids and proteins. More than a hundred proteins related to lipid metabolism, transport, or signaling have been identified and put in perspective of the lipids with which they are associated. This set of data represents an innovative resource to guide further research relative to the organization and functions of the plant PM.
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Affiliation(s)
- Delphine Bahammou
- Laboratoire de Biogenèse Membranaire, CNRS, Université, Bordeaux, (UMR 5200), F-33140, Villenave d'Ornon, France
| | - Ghislaine Recorbet
- UMR Agroécologie, INRAE, Institut Agro Dijon, Université Bourgogne Franche-Comté, F-21000, Dijon, France
| | - Adiilah Mamode Cassim
- UMR Agroécologie, INRAE, Institut Agro Dijon, Université Bourgogne Franche-Comté, F-21000, Dijon, France
| | - Franck Robert
- UMR Agroécologie, INRAE, Institut Agro Dijon, Université Bourgogne Franche-Comté, F-21000, Dijon, France
| | - Thierry Balliau
- Université Paris-Saclay, INRAE, CNRS, AgroParisTech, GQE-Le Moulon, PAPPSO, F-91190, Gif-Sur-Yvette, France
| | - Pierre Van Delft
- Laboratoire de Biogenèse Membranaire, CNRS, Université, Bordeaux, (UMR 5200), F-33140, Villenave d'Ornon, France
| | - Youcef Haddad
- Laboratoire de Biogenèse Membranaire, CNRS, Université, Bordeaux, (UMR 5200), F-33140, Villenave d'Ornon, France
| | - Sébastien Mongrand
- Laboratoire de Biogenèse Membranaire, CNRS, Université, Bordeaux, (UMR 5200), F-33140, Villenave d'Ornon, France
| | - Laetitia Fouillen
- Laboratoire de Biogenèse Membranaire, CNRS, Université, Bordeaux, (UMR 5200), F-33140, Villenave d'Ornon, France
| | - Françoise Simon-Plas
- UMR Agroécologie, INRAE, Institut Agro Dijon, Université Bourgogne Franche-Comté, F-21000, Dijon, France
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4
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Etherington GJ, Wu PS, Oliferenko S, Uhlmann F, Nieduszynski CA. Telomere-to-telomere Schizosaccharomyces japonicus genome assembly reveals hitherto unknown genome features. Yeast 2024; 41:73-86. [PMID: 38451028 DOI: 10.1002/yea.3912] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 10/27/2023] [Accepted: 11/10/2023] [Indexed: 03/08/2024] Open
Abstract
Schizosaccharomyces japonicus belongs to the single-genus class Schizosaccharomycetes, otherwise known as "fission yeasts." As part of a composite model system with its widely studied S. pombe sister species, S. japonicus has provided critical insights into the workings and the evolution of cell biological mechanisms. Furthermore, its divergent biology makes S. japonicus a valuable model organism in its own right. However, the currently available genome assembly contains gaps and has been unable to resolve centromeres and other repeat-rich chromosomal regions. Here we present a telomere-to-telomere long-read genome assembly of the S. japonicus genome. This includes the three megabase-length chromosomes, with centromeres hundreds of kilobases long, rich in 5S ribosomal RNA genes, transfer RNA genes, long terminal repeats, and short repeats. We identify a gene-sparse region on chromosome 2 that resembles a 331 kb centromeric duplication. We revise the genome size of S. japonicus to at least 16.6 Mb and possibly up to 18.12 Mb, at least 30% larger than previous estimates. Our whole genome assembly will support the growing S. japonicus research community and facilitate research in new directions, including centromere and DNA repeat evolution, and yeast comparative genomics.
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Affiliation(s)
| | | | - Snezhana Oliferenko
- The Francis Crick Institute, London, UK
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, UK
| | - Frank Uhlmann
- The Francis Crick Institute, London, UK
- Cell Biology Centre, Institute of Innovative Research, Tokyo Institute of Technology, Kanagawa, Japan
| | - Conrad A Nieduszynski
- The Earlham Institute, Norwich, UK
- School of Biological Sciences, University of East Anglia, Norwich, UK
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5
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Etherington GJ, Gil EG, Haerty W, Oliferenko S, Nieduszynski CA. Schizosaccharomyces versatilis represents a distinct evolutionary lineage of fission yeast. Yeast 2024; 41:95-107. [PMID: 38146786 DOI: 10.1002/yea.3919] [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: 09/04/2023] [Revised: 11/28/2023] [Accepted: 12/01/2023] [Indexed: 12/27/2023] Open
Abstract
The fission yeast species Schizosaccharomyces japonicus is currently divided into two varieties-S. japonicus var. japonicus and S. japonicus var. versatilis. Here we examine the var. versatilis isolate CBS5679. The CBS5679 genome shows 88% identity to the reference genome of S. japonicus var. japonicus at the coding sequence level, with phylogenetic analyses suggesting that it has split from the S. japonicus lineage 25 million years ago. The CBS5679 genome contains a reciprocal translocation between chromosomes 1 and 2, together with several large inversions. The products of genes linked to the major translocation are associated with 'metabolism' and 'cellular assembly' ontology terms. We further show that CBS5679 does not generate viable progeny with the reference strain of S. japonicus. Although CBS5679 shares closer similarity to the 'type' strain of var. versatilis as compared to S. japonicus, it is not identical to the type strain, suggesting population structure within var. versatilis. We recommend that the taxonomic status of S. japonicus var. versatilis is raised, with it being treated as a separate species, Schizosaccharomyces versatilis.
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Affiliation(s)
| | - Elisa Gomez Gil
- Oliferenko Lab, The Francis Crick Institute, London, UK
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, UK
| | - Wilfried Haerty
- Research Faculty, The Earlham Institute, Norwich Research Park, Norwich, UK
| | - Snezhana Oliferenko
- Oliferenko Lab, The Francis Crick Institute, London, UK
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, UK
| | - Conrad A Nieduszynski
- Research Faculty, The Earlham Institute, Norwich Research Park, Norwich, UK
- School of Biological Sciences, University of East Anglia, Norwich, UK
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6
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Nguyen HNA, Sharp L, Lyman E, Saenz JP. Varying the position of phospholipid acyl chain unsaturation modulates hopanoid and sterol ordering. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.09.06.556521. [PMID: 38370701 PMCID: PMC10871177 DOI: 10.1101/2023.09.06.556521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
The cell membrane must balance mechanical stability with fluidity to function as both a barrier and an organizational platform. Key to this balance is the thermodynamic ordering of lipids. Most Eukaryotes employ sterols, which are uniquely capable of modulating lipid order to decouple membrane stability from fluidity. Ancient sterol analogues known as hopanoids are found in many bacteria and are proposed as ancestral ordering lipids. The juxtaposition of sterols and hopanoids in extant organisms prompts us to ask why both pathways persist, especially in light of their convergent ability to order lipids. We reveal that both hopanoids and sterols order unsaturated phospholipids differently based on the position of double bonds in the phospholipid's acyl chain. We find that cholesterol and diplopterol's methyl group distributions lead to distinct effects on unsaturated lipids. In Mesoplasma florum, diplopterol's constrained ordering capacity reduces membrane resistance to osmotic stress, unlike cholesterol. These findings suggest cholesterol's broader lipid ordering ability may have facilitated the exploration of a more diverse lipidomic landscape in eukaryotic membranes.
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Affiliation(s)
- Ha-Ngoc-Anh Nguyen
- Technische Universität Dresden, B CUBE Center for Molecular Bioengineering, 01307 Dresden, Germany
| | - Liam Sharp
- Department of Physics and Astronomy, University of Delaware, Newark DE 19716
- College of Arts and Sciences, Fairfield University, Fairfield, CT 06824
| | - Edward Lyman
- Department of Physics and Astronomy, University of Delaware, Newark DE 19716
- Department of Chemistry and Biochemistry, University of Delaware, Newark DE 19716
| | - James P Saenz
- Technische Universität Dresden, B CUBE Center for Molecular Bioengineering, 01307 Dresden, Germany
- Medical Faculty, Technische Universität Dresden, 01062 Dresden, Germany
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7
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Hall AR, Choi YK, Im W, Vavylonis D. Anillin-related Mid1 as an adaptive and multimodal contractile ring anchoring protein: A simulation study. Structure 2024; 32:242-252.e2. [PMID: 38103546 PMCID: PMC10872332 DOI: 10.1016/j.str.2023.11.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 10/13/2023] [Accepted: 11/21/2023] [Indexed: 12/19/2023]
Abstract
Cytokinesis of animal and fungi cells depends crucially on the anillin scaffold proteins. Fission yeast anillin-related Mid1 anchors cytokinetic ring precursor nodes to the membrane. However, it is unclear if both of its Pleckstrin Homology (PH) and C2 C-terminal domains bind to the membrane as monomers or dimers, and if one domain plays a dominant role. We studied Mid1 membrane binding with all-atom molecular dynamics near a membrane with yeast-like lipid composition. In simulations with the full C terminal region started away from the membrane, Mid1 binds through the disordered L3 loop of C2 in a vertical orientation, with the PH away from the membrane. However, a configuration with both C2 and PH initially bound to the membrane remains associated with the membrane. Simulations of C2-PH dimers show extensive asymmetric membrane contacts. These multiple modes of binding may reflect Mid1's multiple interactions with membranes, node proteins, and ability to sustain mechanical forces.
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Affiliation(s)
- Aaron R Hall
- Department of Physics, Lehigh University, Bethlehem, PA 18017, USA
| | - Yeol Kyo Choi
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18017, USA
| | - Wonpil Im
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18017, USA
| | - Dimitrios Vavylonis
- Department of Physics, Lehigh University, Bethlehem, PA 18017, USA; Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA.
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8
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Willet AH, Wos M, Igarashi MG, Ren L, Turner LA, Gould KL. Elevated levels of sphingolipid MIPC in the plasma membrane disrupt the coordination of cell growth with cell wall formation in fission yeast. PLoS Genet 2023; 19:e1010987. [PMID: 37792890 PMCID: PMC10578601 DOI: 10.1371/journal.pgen.1010987] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 10/16/2023] [Accepted: 09/19/2023] [Indexed: 10/06/2023] Open
Abstract
Coupling cell wall expansion with cell growth is a universal challenge faced by walled organisms. Mutations in Schizosaccharomyces pombe css1, which encodes a PM inositol phosphosphingolipid phospholipase C, prevent cell wall expansion but not synthesis of cell wall material. To probe how Css1 modulates cell wall formation we used classical and chemical genetics coupled with quantitative mass spectrometry. We found that elevated levels of the sphingolipid biosynthetic pathway's final product, mannosylinositol phosphorylceramide (MIPC), specifically correlated with the css1-3 phenotype. We also found that an apparent indicator of sphingolipids and a sterol biosensor accumulated at the cytosolic face of the PM at cell tips and the division site of css1-3 cells and, in accord, the PM in css1-3 was less dynamic than in wildtype cells. Interestingly, disrupting the protein glycosylation machinery recapitulated the css1-3 phenotype and led us to investigate Ghs2, a glycosylated PM protein predicted to modify cell wall material. Disrupting Ghs2 function led to aberrant cell wall material accumulation suggesting Ghs2 is dysfunctional in css1-3. We conclude that preventing an excess of MIPC in the S. pombe PM is critical to the function of key PM-localized proteins necessary for coupling growth with cell wall formation.
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Affiliation(s)
- Alaina H. Willet
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States of America
| | - Marcin Wos
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States of America
| | - Maya G. Igarashi
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States of America
| | - Liping Ren
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States of America
| | - Lesley A. Turner
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States of America
| | - Kathleen L. Gould
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States of America
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9
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Panconi L, Lorenz CD, May RC, Owen DM, Makarova M. Phospholipid tail asymmetry allows cellular adaptation to anoxic environments. J Biol Chem 2023; 299:105134. [PMID: 37562570 PMCID: PMC10482748 DOI: 10.1016/j.jbc.2023.105134] [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: 06/02/2023] [Revised: 07/24/2023] [Accepted: 07/25/2023] [Indexed: 08/12/2023] Open
Abstract
Membrane biophysical properties are critical to cell fitness and depend on unsaturated phospholipid acyl tails. These can only be produced in aerobic environments since eukaryotic desaturases require molecular oxygen. This raises the question of how cells maintain bilayer properties in anoxic environments. Using advanced microscopy, molecular dynamics simulations, and lipidomics by mass spectrometry we demonstrated the existence of an alternative pathway to regulate membrane fluidity that exploits phospholipid acyl tail length asymmetry, replacing unsaturated species in the membrane lipidome. We show that the fission yeast, Schizosaccharomyces japonicus, which can grow in aerobic and anaerobic conditions, is capable of utilizing this strategy, whereas its sister species, the well-known model organism Schizosaccharomyces pombe, cannot. The incorporation of asymmetric-tailed phospholipids might be a general adaptation to hypoxic environmental niches.
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Affiliation(s)
- Luca Panconi
- Institute of Immunology and immunotherapy, School of Mathematics and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
| | - Chris D Lorenz
- Department of Physics, King's College London, London, UK
| | - Robin C May
- Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham, UK
| | - Dylan M Owen
- Institute of Immunology and immunotherapy, School of Mathematics and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
| | - Maria Makarova
- School of Biosciences, Institute of Metabolism and Systems Research and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK.
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10
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Melero A, Jiménez-Rojo N. Cracking the membrane lipid code. Curr Opin Cell Biol 2023; 83:102203. [PMID: 37437490 DOI: 10.1016/j.ceb.2023.102203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/01/2023] [Accepted: 06/16/2023] [Indexed: 07/14/2023]
Abstract
Why has nature acquired such a huge lipid repertoire? Although it would be theoretically possible to make a lipid bilayer fulfilling barrier functions with only one glycerophospholipid, there are diverse and numerous different lipid species. Lipids are heterogeneously distributed across the evolutionary tree with lipidomes evolving in parallel to organismal complexity. Moreover, lipids are different between organs and tissues and even within the same cell, different organelles have characteristic lipid signatures. At the molecular level, membranes are asymmetric and laterally heterogeneous. This lipid asymmetry at different scales indicates that these molecules may play very specific molecular functions in biology. Some of these roles have been recently uncovered: lipids have been shown to be essential in processes such as hypoxia and ferroptosis or in protein sorting and trafficking but many of them remain still unknown. In this review we will discuss the importance of understanding lipid diversity in biology across scales and we will share a toolbox with some of the emerging technologies that are helping us to uncover new lipid molecular functions in cell biology and, step by step, crack the membrane lipid code.
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Affiliation(s)
- Alejandro Melero
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Noemi Jiménez-Rojo
- Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), 48940, Leioa, Spain; Instituto Biofisika (UPV/EHU, CSIC), 48940, Leioa, Spain; Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain.
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11
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Alam S, Gu Y, Reichert P, Bähler J, Oliferenko S. Optimization of energy production and central carbon metabolism in a non-respiring eukaryote. Curr Biol 2023; 33:2175-2186.e5. [PMID: 37164017 PMCID: PMC7615655 DOI: 10.1016/j.cub.2023.04.046] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 03/30/2023] [Accepted: 04/18/2023] [Indexed: 05/12/2023]
Abstract
Most eukaryotes respire oxygen, using it to generate biomass and energy. However, a few organisms have lost the capacity to respire. Understanding how they manage biomass and energy production may illuminate the critical points at which respiration feeds into central carbon metabolism and explain possible routes to its optimization. Here, we use two related fission yeasts, Schizosaccharomyces pombe and Schizosaccharomyces japonicus, as a comparative model system. We show that although S. japonicus does not respire oxygen, unlike S. pombe, it is capable of efficient NADH oxidation, amino acid synthesis, and ATP generation. We probe possible optimization strategies through the use of stable isotope tracing metabolomics, mass isotopologue distribution analysis, genetics, and physiological experiments. S. japonicus appears to have optimized cytosolic NADH oxidation via glycerol-3-phosphate synthesis. It runs a fully bifurcated TCA pathway, sustaining amino acid production. Finally, we propose that it has optimized glycolysis to maintain high ATP/ADP ratio, in part by using the pentose phosphate pathway as a glycolytic shunt, reducing allosteric inhibition of glycolysis and supporting biomass generation. By comparing two related organisms with vastly different metabolic strategies, our work highlights the versatility and plasticity of central carbon metabolism in eukaryotes, illuminating critical adaptations supporting the preferential use of glycolysis over oxidative phosphorylation.
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Affiliation(s)
- Sara Alam
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London SE1 1UL, UK
| | - Ying Gu
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London SE1 1UL, UK
| | - Polina Reichert
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London SE1 1UL, UK; School of Biological and Behavioural Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Jürg Bähler
- Institute of Healthy Ageing, Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
| | - Snezhana Oliferenko
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London SE1 1UL, UK.
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12
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Hall AR, Choi YK, Im W, Vavylonis D. Anillin Related Mid1 as an Adaptive and Multimodal Contractile Ring Anchoring Protein: A Simulation Study. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.27.525865. [PMID: 36747616 PMCID: PMC9900988 DOI: 10.1101/2023.01.27.525865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The organization of the cytokinetic ring at the cell equator of dividing animal and fungi cells depends crucially on the anillin scaffold proteins. In fission yeast, anillin related Mid1 binds to the plasma membrane and helps anchor and organize a medial broad band of cytokinetic nodes, which are the precursors of the contractile ring. Similar to other anillins, Mid1 contains a C terminal globular domain with two potential regions for membrane binding, the Pleckstrin Homology (PH) and C2 domains, and an N terminal intrinsically disordered region that is strongly regulated by phosphorylation. Previous studies have shown that both PH and C2 domains can associate with the membrane, preferring phosphatidylinositol-(4,5)-bisphosphate (PIP 2 ) lipids. However, it is unclear if they can simultaneously bind to the membrane in a way that allows dimerization or oligomerization of Mid1, and if one domain plays a dominant role. To elucidate Mid1's membrane binding mechanism, we used the available structural information of the C terminal region of Mid1 in all-atom molecular dynamics (MD) near a membrane with a lipid composition based on experimental measurements (including PIP 2 lipids). The disordered L3 loop of C2, as well as the PH domain, separately bind the membrane through charged lipid contacts. In simulations with the full C terminal region started away from the membrane, Mid1 binds through the L3 loop and is stabilized in a vertical orientation with the PH domain away from the membrane. However, a configuration with both C2 and PH initially bound to the membrane remains associated with the membrane. These multiple modes of binding may reflect Mid1's multiple interactions with membranes and other node proteins, and ability to sustain mechanical forces.
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13
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Nanoscale Bending Dynamics in Mixed-Chain Lipid Membranes. Symmetry (Basel) 2023. [DOI: 10.3390/sym15010191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Lipids that have two tails of different lengths are found throughout biomembranes in nature, yet the effects of this asymmetry on the membrane properties are not well understood, especially when it comes to the membrane dynamics. Here we study the nanoscale bending fluctuations in model mixed-chain 14:0–18:0 PC (MSPC) and 18:0–14:0 PC (SMPC) lipid bilayers using neutron spin echo (NSE) spectroscopy. We find that despite the partial interdigitation that is known to persist in the fluid phase of these membranes, the collective fluctuations are enhanced on timescales of tens of nanoseconds, and the chain-asymmetric lipid bilayers are softer than an analogous chain-symmetric lipid bilayer with the same average number of carbons in the acyl tails, di-16:0 PC (DPPC). Quantitative comparison of the NSE results suggests that the enhanced bending fluctuations at the nanosecond timescales are consistent with experimental and computational studies that showed the compressibility moduli of chain-asymmetric lipid membranes are 20% to 40% lower than chain-symmetric lipid membranes. These studies add to growing evidence that the partial interdigitation in mixed-chain lipid membranes is highly dynamic in the fluid phase and impacts membrane dynamic processes from the molecular to mesoscopic length scales without significantly changing the bilayer thickness or area per lipid.
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14
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Transient Complexity of E. coli Lipidome Is Explained by Fatty Acyl Synthesis and Cyclopropanation. Metabolites 2022; 12:metabo12090784. [PMID: 36144187 PMCID: PMC9500627 DOI: 10.3390/metabo12090784] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 08/22/2022] [Accepted: 08/23/2022] [Indexed: 12/04/2022] Open
Abstract
In the case of many bacteria, such as Escherichia coli, the composition of lipid molecules, termed the lipidome, temporally adapts to different environmental conditions and thus modifies membrane properties to permit growth and survival. Details of the relationship between the environment and lipidome composition are lacking, particularly for growing cultures under either favourable or under stress conditions. Here, we highlight compositional lipidome changes by describing the dynamics of molecular species throughout culture-growth phases. We show a steady cyclopropanation of fatty acyl chains, which acts as a driver for lipid diversity. There is a bias for the cyclopropanation of shorter fatty acyl chains (FA 16:1) over longer ones (FA 18:1), which likely reflects a thermodynamic phenomenon. Additionally, we observe a nearly two-fold increase in saturated fatty acyl chains in response to the presence of ampicillin and chloramphenicol, with consequences for membrane fluidity and elasticity, and ultimately bacterial stress tolerance. Our study provides the detailed quantitative lipidome composition of three E. coli strains across culture-growth phases and at the level of the fatty acyl chains and provides a general reference for phospholipid composition changes in response to perturbations. Thus, lipidome diversity is largely transient and the consequence of lipid synthesis and cyclopropanation.
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15
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Makarova M, Owen DM. Quantitative Measurements of Membrane Lipid Order in Yeast and Fungi. Methods Mol Biol 2022; 2402:291-298. [PMID: 34854052 DOI: 10.1007/978-1-0716-1843-1_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Membrane lateral heterogeneity, historically referred to as the lipid raft hypothesis, has been extensively investigated through physiochemical experiments on model membranes. Currently, the basic principles are well understood; however, the physiological relevance of these structures in living organisms is still not clear. Thus, studying membrane organization in vivo is extremely important and elucidates the role of such structures in various membrane-associated processes. This is particularly true when a whole single-celled organism can be studied rather than an isolated cell. The ordered and disordered membrane phases are characterized by the degree of acyl chain packing in the lipid bilayer. Polar water molecules can penetrate into the low-density lipid packing of the disordered phase, but are more excluded from the tightly packed ordered phase. Here, polarity-sensitive probes, embedded in the lipid bilayer, are used to report on membrane organization and to quantitate this parameter via 2-channel fluorescence microscopy. Coupling genetic approaches, which are easily accessible in yeast model organisms, with the imaging approach described here provides a great opportunity to investigate how membrane heterogeneity impacts physiology.
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Affiliation(s)
- Maria Makarova
- School of Biosciences, University of Birmingham, Birmingham, UK.
| | - Dylan M Owen
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK
- School of Mathematics, University of Birmingham, Birmingham, UK
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16
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Rutherford KM, Harris MA, Oliferenko S, Wood V. JaponicusDB: rapid deployment of a model organism database for an emerging model species. Genetics 2021; 220:6481558. [PMID: 35380656 PMCID: PMC9209809 DOI: 10.1093/genetics/iyab223] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 11/09/2021] [Indexed: 02/03/2023] Open
Abstract
The fission yeast Schizosaccharomyces japonicus has recently emerged as a powerful system for studying the evolution of essential cellular processes, drawing on similarities as well as key differences between S. japonicus and the related, well-established model Schizosaccharomyces pombe. We have deployed the open-source, modular code and tools originally developed for PomBase, the S. pombe model organism database (MOD), to create JaponicusDB (www.japonicusdb.org), a new MOD dedicated to S. japonicus. By providing a central resource with ready access to a growing body of experimental data, ontology-based curation, seamless browsing and querying, and the ability to integrate new data with existing knowledge, JaponicusDB supports fission yeast biologists to a far greater extent than any other source of S. japonicus data. JaponicusDB thus enables S. japonicus researchers to realize the full potential of studying a newly emerging model species and illustrates the widely applicable power and utility of harnessing reusable PomBase code to build a comprehensive, community-maintainable repository of species-relevant knowledge.
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Affiliation(s)
- Kim M Rutherford
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Midori A Harris
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Snezhana Oliferenko
- The Francis Crick Institute, London NW1 1AT, UK,Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King’s College London, London SE1 1UL, UK,Corresponding author: (S.O.); (V.W.)
| | - Valerie Wood
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK,Corresponding author: (S.O.); (V.W.)
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17
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Yagüe N, Gómez-Delgado L, Curto MÁ, Carvalho VSD, Moreno MB, Pérez P, Ribas JC, Cortés JCG. Echinocandin Drugs Induce Differential Effects in Cytokinesis Progression and Cell Integrity. Pharmaceuticals (Basel) 2021; 14:ph14121332. [PMID: 34959732 PMCID: PMC8706178 DOI: 10.3390/ph14121332] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 12/14/2022] Open
Abstract
Fission yeast contains three essential β(1,3)-D-glucan synthases (GSs), Bgs1, Bgs3, and Bgs4, with non-overlapping roles in cell integrity and morphogenesis. Only the bgs4+ mutants pbr1-8 and pbr1-6 exhibit resistance to GS inhibitors, even in the presence of the wild-type (WT) sequences of bgs1+ and bgs3+. Thus, Bgs1 and Bgs3 functions seem to be unaffected by those GS inhibitors. To learn more about echinocandins' mechanism of action and resistance, cytokinesis progression and cell death were examined by time-lapse fluorescence microscopy in WT and pbr1-8 cells at the start of treatment with sublethal and lethal concentrations of anidulafungin, caspofungin, and micafungin. In WT, sublethal concentrations of the three drugs caused abundant cell death that was either suppressed (anidulafungin and micafungin) or greatly reduced (caspofungin) in pbr1-8 cells. Interestingly, the lethal concentrations induced differential phenotypes depending on the echinocandin used. Anidulafungin and caspofungin were mostly fungistatic, heavily impairing cytokinesis progression in both WT and pbr1-8. As with sublethal concentrations, lethal concentrations of micafungin were primarily fungicidal in WT cells, causing cell lysis without impairing cytokinesis. The lytic phenotype was suppressed again in pbr1-8 cells. Our results suggest that micafungin always exerts its fungicidal effect by solely inhibiting Bgs4. In contrast, lethal concentrations of anidulafungin and caspofungin cause an early cytokinesis arrest, probably by the combined inhibition of several GSs.
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18
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Lipids and Trehalose Actively Cooperate in Heat Stress Management of Schizosaccharomyces pombe. Int J Mol Sci 2021; 22:ijms222413272. [PMID: 34948069 PMCID: PMC8707580 DOI: 10.3390/ijms222413272] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/04/2021] [Accepted: 12/08/2021] [Indexed: 01/22/2023] Open
Abstract
Homeostatic maintenance of the physicochemical properties of cellular membranes is essential for life. In yeast, trehalose accumulation and lipid remodeling enable rapid adaptation to perturbations, but their crosstalk was not investigated. Here we report about the first in-depth, mass spectrometry-based lipidomic analysis on heat-stressed Schizosaccharomyces pombe mutants which are unable to synthesize (tps1Δ) or degrade (ntp1Δ) trehalose. Our experiments provide data about the role of trehalose as a membrane protectant in heat stress. We show that under conditions of trehalose deficiency, heat stress induced a comprehensive, distinctively high-degree lipidome reshaping in which structural, signaling and storage lipids acted in concert. In the absence of trehalose, membrane lipid remodeling was more pronounced and increased with increasing stress dose. It could be characterized by decreasing unsaturation and increasing acyl chain length, and required de novo synthesis of stearic acid (18:0) and very long-chain fatty acids to serve membrane rigidification. In addition, we detected enhanced and sustained signaling lipid generation to ensure transient cell cycle arrest as well as more intense triglyceride synthesis to accommodate membrane lipid-derived oleic acid (18:1) and newly synthesized but unused fatty acids. We also demonstrate that these changes were able to partially substitute for the missing role of trehalose and conferred measurable stress tolerance to fission yeast cells.
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19
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A squalene-hopene cyclase in Schizosaccharomyces japonicus represents a eukaryotic adaptation to sterol-limited anaerobic environments. Proc Natl Acad Sci U S A 2021; 118:2105225118. [PMID: 34353908 PMCID: PMC8364164 DOI: 10.1073/pnas.2105225118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Biosynthesis of sterols requires oxygen. This study identifies a previously unknown evolutionary adaptation in a eukaryote, which enables anaerobic growth in absence of exogenous sterols. A squalene–hopene cyclase, proposed to have been acquired by horizontal gene transfer from an acetic acid bacterium, is implicated in a unique ability of the yeast Schizosaccharomyces japonicus to synthesize hopanoids and grow in anaerobic, sterol-free media. Expression of this cyclase in Saccharomyces cerevisiae confirmed that at least one of its hopanoid products acts as sterol surrogate. These observations provide leads for research into the structure and function of eukaryotic membranes and into the development of sterol-independent yeast cell factories for application in anaerobic processes. Biosynthesis of sterols, which are key constituents of canonical eukaryotic membranes, requires molecular oxygen. Anaerobic protists and deep-branching anaerobic fungi are the only eukaryotes in which a mechanism for sterol-independent growth has been elucidated. In these organisms, tetrahymanol, formed through oxygen-independent cyclization of squalene by a squalene–tetrahymanol cyclase, acts as a sterol surrogate. This study confirms an early report [C. J. E. A. Bulder, Antonie Van Leeuwenhoek, 37, 353–358 (1971)] that Schizosaccharomyces japonicus is exceptional among yeasts in growing anaerobically on synthetic media lacking sterols and unsaturated fatty acids. Mass spectrometry of lipid fractions of anaerobically grown Sch. japonicus showed the presence of hopanoids, a class of cyclic triterpenoids not previously detected in yeasts, including hop-22(29)-ene, hop-17(21)-ene, hop-21(22)-ene, and hopan-22-ol. A putative gene in Sch. japonicus showed high similarity to bacterial squalene–hopene cyclase (SHC) genes and in particular to those of Acetobacter species. No orthologs of the putative Sch. japonicus SHC were found in other yeast species. Expression of the Sch. japonicus SHC gene (Sjshc1) in Saccharomyces cerevisiae enabled hopanoid synthesis and stimulated anaerobic growth in sterol-free media, thus indicating that one or more of the hopanoids produced by SjShc1 could at least partially replace sterols. Use of hopanoids as sterol surrogates represents a previously unknown adaptation of eukaryotic cells to anaerobic growth. The fast anaerobic growth of Sch. japonicus in sterol-free media is an interesting trait for developing robust fungal cell factories for application in anaerobic industrial processes.
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20
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Gómez-Gil E, Franco A, Vázquez-Marín B, Prieto-Ruiz F, Pérez-Díaz A, Vicente-Soler J, Madrid M, Soto T, Cansado J. Specific Functional Features of the Cell Integrity MAP Kinase Pathway in the Dimorphic Fission Yeast Schizosaccharomyces japonicus. J Fungi (Basel) 2021; 7:jof7060482. [PMID: 34198697 PMCID: PMC8232204 DOI: 10.3390/jof7060482] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 06/10/2021] [Accepted: 06/11/2021] [Indexed: 11/16/2022] Open
Abstract
Mitogen activated protein kinase (MAPK) signaling pathways execute essential functions in eukaryotic organisms by transducing extracellular stimuli into adaptive cellular responses. In the fission yeast model Schizosaccharomyces pombe the cell integrity pathway (CIP) and its core effector, MAPK Pmk1, play a key role during regulation of cell integrity, cytokinesis, and ionic homeostasis. Schizosaccharomyces japonicus, another fission yeast species, shows remarkable differences with respect to S. pombe, including a robust yeast to hyphae dimorphism in response to environmental changes. We show that the CIP MAPK module architecture and its upstream regulators, PKC orthologs Pck1 and Pck2, are conserved in both fission yeast species. However, some of S. pombe's CIP-related functions, such as cytokinetic control and response to glucose availability, are regulated differently in S. japonicus. Moreover, Pck1 and Pck2 antagonistically regulate S. japonicus hyphal differentiation through fine-tuning of Pmk1 activity. Chimeric MAPK-swapping experiments revealed that S. japonicus Pmk1 is fully functional in S. pombe, whereas S. pombe Pmk1 shows a limited ability to execute CIP functions and promote S. japonicus mycelial development. Our findings also suggest that a modified N-lobe domain secondary structure within S. japonicus Pmk1 has a major influence on the CIP signaling features of this evolutionarily diverged fission yeast.
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21
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Smith P, Owen DM, Lorenz CD, Makarova M. Asymmetric glycerophospholipids impart distinctive biophysical properties to lipid bilayers. Biophys J 2021; 120:1746-1754. [PMID: 33705758 DOI: 10.1016/j.bpj.2021.02.046] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 02/23/2021] [Accepted: 02/24/2021] [Indexed: 01/25/2023] Open
Abstract
Phospholipids are a diverse group of biomolecules consisting of a hydrophilic headgroup and two hydrophobic acyl tails. The nature of the head and length and saturation of the acyl tails are important for defining the biophysical properties of lipid bilayers. It has recently been shown that the membranes of certain yeast species contain high levels of unusual asymmetric phospholipids consisting of one long and one medium-chain acyl moiety, a configuration not common in mammalian cells or other well-studied model yeast species. This raises the possibility that structurally asymmetric glycerophospholipids impart distinctive biophysical properties to the yeast membranes. Previously, it has been shown that lipids with asymmetric length tails form a mixed interdigitated gel phase and exhibit unusual endotherm behavior upon heating and cooling. Here, however, we address physiologically relevant temperature conditions and, using atomistic molecular dynamics simulations and environmentally sensitive fluorescent membrane probes, characterize key biophysical parameters (such as lipid packing, diffusion coefficient, membrane thickness, and area per lipid) in membranes composed of both length-asymmetric glycerophospholipids and ergosterol. Interestingly, we show that saturated but asymmetric glycerophospholipids maintain membrane lipid order across a wide range of temperatures. We also show that these asymmetric lipids can substiture of unsaturated symmetric lipids in the phase behaviour of ternary lipid bilayers. This may allow cells to maintain membrane fluidity, even in environments that lack oxygen, which is required for the synthesis of unsaturated lipids and sterols.
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Affiliation(s)
- Paul Smith
- Department of Physics, King's College London, London, United Kingdom
| | - Dylan M Owen
- Institute of Immunology and Immunotherapy, College of Medical and Dental Sciences and School of Mathematics, College of Engineering and Physical Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | | | - Maria Makarova
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
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22
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23
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Reinhard J, Mattes C, Väth K, Radanović T, Surma MA, Klose C, Ernst R. A Quantitative Analysis of Cellular Lipid Compositions During Acute Proteotoxic ER Stress Reveals Specificity in the Production of Asymmetric Lipids. Front Cell Dev Biol 2020; 8:756. [PMID: 32850859 PMCID: PMC7417482 DOI: 10.3389/fcell.2020.00756] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 07/20/2020] [Indexed: 12/12/2022] Open
Abstract
The unfolded protein response (UPR) is central to endoplasmic reticulum (ER) homeostasis by controlling its size and protein folding capacity. When activated by unfolded proteins in the ER-lumen or aberrant lipid compositions, the UPR adjusts the expression of hundreds of target genes to counteract ER stress. The proteotoxic drugs dithiothreitol (DTT) and tunicamycin (TM) are commonly used to induce misfolding of proteins in the ER and to study the UPR. However, their potential impact on the cellular lipid composition has never been systematically addressed. Here, we report the quantitative, cellular lipid composition of Saccharomyces cerevisiae during acute, proteotoxic stress in both rich and synthetic media. We show that DTT causes rapid remodeling of the lipidome when used in rich medium at growth-inhibitory concentrations, while TM has only a marginal impact on the lipidome under our conditions of cultivation. We formulate recommendations on how to study UPR activation by proteotoxic stress without interferences from a perturbed lipid metabolism. Furthermore, our data suggest an intricate connection between the cellular growth rate, the abundance of the ER, and the metabolism of fatty acids. We show that Saccharomyces cerevisiae can produce asymmetric lipids with two saturated fatty acyl chains differing substantially in length. These observations indicate that the pairing of saturated fatty acyl chains is tightly controlled and suggest an evolutionary conservation of asymmetric lipids and their biosynthetic machineries.
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Affiliation(s)
- John Reinhard
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | - Carsten Mattes
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | - Kristina Väth
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | - Toni Radanović
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | | | | | - Robert Ernst
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
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24
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Lee IJ, Stokasimov E, Dempsey N, Varberg JM, Jacob E, Jaspersen SL, Pellman D. Factors promoting nuclear envelope assembly independent of the canonical ESCRT pathway. J Cell Biol 2020; 219:e201908232. [PMID: 32243490 PMCID: PMC7265314 DOI: 10.1083/jcb.201908232] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 01/11/2020] [Accepted: 03/03/2020] [Indexed: 01/15/2023] Open
Abstract
The nuclear envelope (NE) undergoes dynamic remodeling to maintain NE integrity, a process involving the inner nuclear membrane protein LEM2 recruiting CHMP7/Cmp7 and then ESCRT-III. However, prior work has hinted at CHMP7/ESCRT-independent mechanisms. To identify such mechanisms, we studied NE assembly in Schizosaccharomyces japonicus, a fission yeast that undergoes partial mitotic NE breakdown and reassembly. S. japonicus cells lacking Cmp7 have compromised NE sealing after mitosis but are viable. A genetic screen identified mutations that promote NE integrity in cmp7Δ cells. Unexpectedly, loss of Lem2 or its interacting partner Nur1 suppressed cmp7Δ defects. In the absence of Cmp7, Lem2 formed aggregates that appear to interfere with ESCRT-independent NE sealing. A gain-of-function mutation implicated a membrane and ESCRT-III regulator, Alx1, in this alternate pathway. Additional results suggest a potentially general role for unsaturated fatty acids in NE integrity. These findings establish the existence of mechanisms for NE sealing independent of the canonical ESCRT pathway.
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Affiliation(s)
- I-Ju Lee
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Ema Stokasimov
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Nathaniel Dempsey
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | | | - Etai Jacob
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
| | - Sue L. Jaspersen
- Stowers Institute for Medical Research, Kansas City, MO
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS
| | - David Pellman
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
- Howard Hughes Medical Institute, Chevy Chase, MD
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25
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López-García P, Moreira D. The Syntrophy hypothesis for the origin of eukaryotes revisited. Nat Microbiol 2020; 5:655-667. [DOI: 10.1038/s41564-020-0710-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 03/13/2020] [Indexed: 11/10/2022]
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26
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Abstract
A new study compares two sister species of fission yeast that use very different fatty acids to make membrane lipids and reveals an adaptation in transmembrane helix lengths that maintains membrane protein functions.
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Affiliation(s)
- Takeshi Harayama
- Department of Biochemistry and National Centre of Competence in Research in Chemical Biology, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland.
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