51
|
Cecchetti C, Pyle E, Byrne B. Transporter oligomerisation: roles in structure and function. Biochem Soc Trans 2019; 47:433-40. [PMID: 30578344 DOI: 10.1042/BST20180316] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/18/2018] [Accepted: 11/15/2018] [Indexed: 01/27/2023]
Abstract
Oligomerisation is a key feature of integral membrane transporters with roles in structure, function and stability. In this review, we cover some very recent advances in our understanding of how oligomerisation affects these key transporter features, with emphasis on a few groups of transporters, including the nucleobase ascorbate transporters, neurotransmitter sodium symporters and major facilitator superfamily members.
Collapse
|
52
|
Cuypers MG, Subramanian C, Gullett JM, Frank MW, White SW, Rock CO. Acyl-chain selectivity and physiological roles of Staphylococcus aureus fatty acid-binding proteins. J Biol Chem 2018; 294:38-49. [PMID: 30429218 DOI: 10.1074/jbc.ra118.006160] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 10/25/2018] [Indexed: 12/22/2022] Open
Abstract
Fatty acid (FA) kinase produces acyl-phosphate for the synthesis of membrane phospholipids in Gram-positive bacterial pathogens. FA kinase consists of a kinase protein (FakA) that phosphorylates an FA substrate bound to a second module, an FA-binding protein (FakB). Staphylococcus aureus expresses two distinct, but related, FakBs with different FA selectivities. Here, we report the structures of FakB1 bound to four saturated FAs at 1.6-1.93 Å resolution. We observed that the different FA structures are accommodated within a slightly curved hydrophobic cavity whose length is governed by the conformation of an isoleucine side chain at the end of the tunnel. The hydrophobic tunnel in FakB1 prevents the binding of cis-unsaturated FAs, which are instead accommodated by the kinked tunnel within the FakB2 protein. The differences in the FakB interiors are not propagated to the proteins' surfaces, preserving the protein-protein interactions with their three common partners, FakA, PlsX, and PlsY. Using cellular thermal shift analyses, we found that FakB1 binds FA in vivo, whereas a significant proportion of FakB2 does not. Incorporation of exogenous FA into phospholipid in ΔfakB1 and ΔfakB2 S. aureus knockout strains revealed that FakB1 does not efficiently activate unsaturated FAs. FakB2 preferred unsaturated FAs, but also allowed the incorporation of saturated FAs. These results are consistent with a model in which FakB1 primarily functions in the recycling of the saturated FAs produced by S. aureus metabolism, whereas FakB2 activates host-derived oleate, which S. aureus does not produce but is abundant at infection sites.
Collapse
Affiliation(s)
- Maxime G Cuypers
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Chitra Subramanian
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Jessica M Gullett
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Matthew W Frank
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Stephen W White
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Charles O Rock
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee 38105.
| |
Collapse
|
53
|
Nganga R, Oleinik N, Kim J, Selvam SP, De Palma R, Johnson KA, Parikh RY, Gangaraju V, Peterson Y, Dany M, Stahelin RV, Voelkel-Johnson C, Szulc ZM, Bieberich E, Ogretmen B. Receptor-interacting Ser/Thr kinase 1 (RIPK1) and myosin IIA-dependent ceramidosomes form membrane pores that mediate blebbing and necroptosis. J Biol Chem 2018; 294:502-519. [PMID: 30420430 DOI: 10.1074/jbc.ra118.005865] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 11/08/2018] [Indexed: 12/29/2022] Open
Abstract
Formation of membrane pores/channels regulates various cellular processes, such as necroptosis or stem cell niche signaling. However, the roles of membrane lipids in the formation of pores and their biological functions are largely unknown. Here, using the cellular stress model evoked by the sphingolipid analog drug FTY720, we show that formation of ceramide-enriched membrane pores, referred to here as ceramidosomes, is initiated by a receptor-interacting Ser/Thr kinase 1 (RIPK1)-ceramide complex transported to the plasma membrane by nonmuscle myosin IIA-dependent trafficking in human lung cancer cells. Molecular modeling/simulation coupled with site-directed mutagenesis revealed that Asp147 or Asn169 of RIPK1 are key for ceramide binding and that Arg258 or Leu293 residues are involved in the myosin IIA interaction, leading to ceramidosome formation and necroptosis. Moreover, generation of ceramidosomes independently of any external drug/stress stimuli was also detected in the plasma membrane of germ line stem cells in ovaries during the early stages of oogenesis in Drosophila melanogaster Inhibition of ceramidosome formation via myosin IIA silencing limited germ line stem cell signaling and abrogated oogenesis. In conclusion, our findings indicate that the RIPK1-ceramide complex forms large membrane pores we named ceramidosomes. They further suggest that, in addition to their roles in stress-mediated necroptosis, these ceramide-enriched pores also regulate membrane integrity and signaling and might also play a role in D. melanogaster ovary development.
Collapse
Affiliation(s)
- Rose Nganga
- From the Department of Biochemistry and Molecular Biology and.,Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Natalia Oleinik
- From the Department of Biochemistry and Molecular Biology and.,Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Jisun Kim
- From the Department of Biochemistry and Molecular Biology and.,Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Shanmugam Panneer Selvam
- From the Department of Biochemistry and Molecular Biology and.,Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Ryan De Palma
- From the Department of Biochemistry and Molecular Biology and.,Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Kristen A Johnson
- Department of Chemistry and Biochemistry, University of Notre Dame, South Bend, Indiana, 46617
| | - Rasesh Y Parikh
- From the Department of Biochemistry and Molecular Biology and
| | - Vamsi Gangaraju
- From the Department of Biochemistry and Molecular Biology and
| | - Yuri Peterson
- the College of Pharmacy/Pharmaceutical and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, 29425
| | - Mohammed Dany
- From the Department of Biochemistry and Molecular Biology and.,Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Robert V Stahelin
- the Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907
| | | | | | - Erhard Bieberich
- the Department of Neuroscience and Regenerative Medicine, Augusta University, Augusta, Georgia 30912, and.,the Department of Physiology, University of Kentucky, Lexington, Kentucky 40506
| | - Besim Ogretmen
- From the Department of Biochemistry and Molecular Biology and .,Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina 29425
| |
Collapse
|
54
|
Tran DM, Takagi H, Kimata Y. Categorization of endoplasmic reticulum stress as accumulation of unfolded proteins or membrane lipid aberrancy using yeast Ire1 mutants. Biosci Biotechnol Biochem 2018; 83:326-329. [PMID: 30319071 DOI: 10.1080/09168451.2018.1530098] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Endoplasmic reticulum (ER)-located protein Ire1 triggers the unfolded protein response against ER-stressing stimuli, which are categorized as ER accumulation of unfolded proteins or membrane lipid-related aberrancy. Here we demonstrate that by using yeast Ire1 mutants, we can distinguish the category to which a stress-inducing stimulus belongs. For instance, ethanol was found to activate Ire1 through both types of cellular damage.
Collapse
Affiliation(s)
- Duc Minh Tran
- a Graduate School of Science and Technology , Nara Institute of Science and Technology , Nara , Japan.,b Institute of Biotechnology , Vietnam Academy of Science and Technology , Ha Noi , Viet Nam
| | - Hiroshi Takagi
- a Graduate School of Science and Technology , Nara Institute of Science and Technology , Nara , Japan
| | - Yukio Kimata
- a Graduate School of Science and Technology , Nara Institute of Science and Technology , Nara , Japan
| |
Collapse
|
55
|
Bozelli JC, Jennings W, Black S, Hou YH, Lameire D, Chatha P, Kimura T, Berno B, Khondker A, Rheinstädter MC, Epand RM. Membrane curvature allosterically regulates the phosphatidylinositol cycle, controlling its rate and acyl-chain composition of its lipid intermediates. J Biol Chem 2018; 293:17780-17791. [PMID: 30237168 DOI: 10.1074/jbc.ra118.005293] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 09/04/2018] [Indexed: 01/17/2023] Open
Abstract
Signaling events at membranes are often mediated by membrane lipid composition or membrane physical properties. These membrane properties could act either by favoring the membrane binding of downstream effectors or by modulating their activity. Several proteins can sense/generate membrane physical curvature (i.e. shape). However, the modulation of the activity of enzymes by a membrane's shape has not yet been reported. Here, using a cell-free assay with purified diacylglycerol kinase ϵ (DGKϵ) and liposomes, we studied the activity and acyl-chain specificity of an enzyme of the phosphatidylinositol (PI) cycle, DGKϵ. By systematically varying the model membrane lipid composition and physical properties, we found that DGKϵ has low activity and lacks acyl-chain specificity in locally flat membranes, regardless of the lipid composition. On the other hand, these enzyme properties were greatly enhanced in membrane structures with a negative Gaussian curvature. We also found that this is not a consequence of preferential binding of the enzyme to those structures, but rather is due to a curvature-mediated allosteric regulation of DGKϵ activity and acyl-chain specificity. Moreover, in a fine-tuned interplay between the enzyme and the membrane, DGKϵ favored the formation of structures with greater Gaussian curvature. DGKϵ does not bear a regulatory domain, and these findings reveal the importance of membrane curvature in regulating DGKϵ activity and acyl-chain specificity. Hence, this study highlights that a hierarchic coupling of membrane physical property and lipid composition synergistically regulates membrane signaling events. We propose that this regulatory mechanism of membrane-associated enzyme activity is likely more common than is currently appreciated.
Collapse
Affiliation(s)
- José Carlos Bozelli
- From the Department of Biochemistry and Biomedical Sciences, Health Sciences Centre, McMaster University, Hamilton, Ontario L8S 4K1
| | - William Jennings
- From the Department of Biochemistry and Biomedical Sciences, Health Sciences Centre, McMaster University, Hamilton, Ontario L8S 4K1
| | - Stephanie Black
- From the Department of Biochemistry and Biomedical Sciences, Health Sciences Centre, McMaster University, Hamilton, Ontario L8S 4K1
| | - Yu Heng Hou
- From the Department of Biochemistry and Biomedical Sciences, Health Sciences Centre, McMaster University, Hamilton, Ontario L8S 4K1
| | - Darius Lameire
- From the Department of Biochemistry and Biomedical Sciences, Health Sciences Centre, McMaster University, Hamilton, Ontario L8S 4K1
| | - Preet Chatha
- From the Department of Biochemistry and Biomedical Sciences, Health Sciences Centre, McMaster University, Hamilton, Ontario L8S 4K1
| | - Tomohiro Kimura
- From the Department of Biochemistry and Biomedical Sciences, Health Sciences Centre, McMaster University, Hamilton, Ontario L8S 4K1
| | | | - Adree Khondker
- Physics and Astronomy; Origins Institute, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - Maikel C Rheinstädter
- Physics and Astronomy; Origins Institute, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - Richard M Epand
- From the Department of Biochemistry and Biomedical Sciences, Health Sciences Centre, McMaster University, Hamilton, Ontario L8S 4K1; Departments of Chemistry.
| |
Collapse
|
56
|
de Boer TE, Roelofs D, Vooijs R, Holmstrup M, Amorim MJB. Population-specific transcriptional differences associated with freeze tolerance in a terrestrial worm. Ecol Evol 2018; 8:3774-3786. [PMID: 29686857 PMCID: PMC5901168 DOI: 10.1002/ece3.3602] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 10/13/2017] [Accepted: 10/13/2017] [Indexed: 12/25/2022] Open
Abstract
Enchytraeus albidus is a terrestrial earthworm widespread along the coasts of northern Europe and the Arctic. This species tolerates freezing of body fluids and survives winters in a frozen state. Their acclimatory physiological mechanisms behind freeze tolerance involve increased fluidity of membrane lipids during cold exposure and accumulation of cryoprotectants (glucose) during the freezing process. Gene regulatory processes of these physiological responses have not been studied, partly because no gene expression tools were developed. The main aim of this study was to understand whether the freeze tolerance mechanisms have a transcriptomic basis in E. albidus. For that purpose, first the transcriptome of E. albidus was assembled with RNAseq data. Second, two strains from contrasting thermal environments (Germany and Greenland) were compared by mapping barcoded RNAseq data onto the assembled transcriptome. Both of these strains are freeze tolerant, but Greenland is extremely freeze tolerant. Results showed more plastic responses in the Greenland strain as well as higher constitutive expression of particular stress response genes. These altered transcriptional networks are associated with an adapted homeostasis coping with prolonged freezing conditions in Greenland animals. Previously identified physiological alterations in freeze‐tolerant strains of E. albidus are underpinned at the transcriptome level. These processes involve anion transport in the hemolymph, fatty acid metabolism, metabolism, and transport of cryoprotective sugars as well as protection against oxidative stress. Pathway analysis supported most of these processes, and identified additional differentially expressed pathways such as peroxisome and Toll‐like receptor signaling. We propose that the freeze‐tolerant phenotype is the consequence of genetic adaptation to cold stress and may have driven evolutionary divergence of the two strains.
Collapse
Affiliation(s)
| | - Dick Roelofs
- Department of Ecological Science Faculty of Earth and Life Sciences VU University, Amsterdam Amsterdam The Netherlands
| | - Riet Vooijs
- Department of Ecological Science Faculty of Earth and Life Sciences VU University, Amsterdam Amsterdam The Netherlands
| | | | - Mónica J B Amorim
- Department of Biology and CESAM (Centre for Environmental and Marine Studies) University of Aveiro Aveiro Portugal
| |
Collapse
|
57
|
Lin Y, Bogdanov M, Lu S, Guan Z, Margolin W, Weiss J, Zheng L. The phospholipid-repair system LplT/Aas in Gram-negative bacteria protects the bacterial membrane envelope from host phospholipase A 2 attack. J Biol Chem 2018; 293:3386-3398. [PMID: 29348168 PMCID: PMC5836115 DOI: 10.1074/jbc.ra117.001231] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 01/15/2018] [Indexed: 11/06/2022] Open
Abstract
Secretory phospholipases A2 (sPLA2s) are potent components of mammalian innate-immunity antibacterial mechanisms. sPLA2 enzymes attack bacteria by hydrolyzing bacterial membrane phospholipids, causing membrane disorganization and cell lysis. However, most Gram-negative bacteria are naturally resistant to sPLA2 Here we report a novel resistance mechanism to mammalian sPLA2 in Escherichia coli, mediated by a phospholipid repair system consisting of the lysophospholipid transporter LplT and the acyltransferase Aas in the cytoplasmic membrane. Mutation of the lplT or aas gene abolished bacterial lysophospholipid acylation activity and drastically increased bacterial susceptibility to the combined actions of inflammatory fluid components and sPLA2, resulting in bulk phospholipid degradation and loss of colony-forming ability. sPLA2-mediated hydrolysis of the three major bacterial phospholipids exhibited distinctive kinetics and deacylation of cardiolipin to its monoacyl-derivative closely paralleled bacterial death. Characterization of the membrane envelope in lplT- or aas-knockout mutant bacteria revealed reduced membrane packing and disruption of lipid asymmetry with more phosphatidylethanolamine present in the outer leaflet of the outer membrane. Moreover, modest accumulation of lysophospholipids in these mutant bacteria destabilized the inner membrane and rendered outer membrane-depleted spheroplasts much more sensitive to sPLA2 These findings indicated that LplT/Aas inactivation perturbs both the outer and inner membranes by bypassing bacterial membrane maintenance mechanisms to trigger specific interfacial activation of sPLA2 We conclude that the LplT/Aas system is important for maintaining the integrity of the membrane envelope in Gram-negative bacteria. Our insights may help inform new therapeutic strategies to enhance host sPLA2 antimicrobial activity.
Collapse
Affiliation(s)
- Yibin Lin
- From the Center for Membrane Biology, Department of Biochemistry and Molecular Biology and
| | | | - Shuo Lu
- From the Center for Membrane Biology, Department of Biochemistry and Molecular Biology and
| | - Ziqiang Guan
- the Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina 27710, and
| | - William Margolin
- Microbiology and Molecular Genetics, University of Texas McGovern Medical School, Houston, Texas 77030
| | - Jerrold Weiss
- the Inflammation Program and Departments of Internal Medicine and Microbiology, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - Lei Zheng
- From the Center for Membrane Biology, Department of Biochemistry and Molecular Biology and
| |
Collapse
|
58
|
Laursen L, Severinsen K, Kristensen KB, Periole X, Overby M, Müller HK, Schiøtt B, Sinning S. Cholesterol binding to a conserved site modulates the conformation, pharmacology, and transport kinetics of the human serotonin transporter. J Biol Chem 2018; 293:3510-3523. [PMID: 29352106 DOI: 10.1074/jbc.m117.809046] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 01/14/2018] [Indexed: 12/31/2022] Open
Abstract
The serotonin transporter (SERT) is important for reuptake of the neurotransmitter serotonin from the synaptic cleft and is also the target of most antidepressants. It has previously been shown that cholesterol in the membrane bilayer affects the conformation of SERT. Although recent crystal structures have identified several potential cholesterol-binding sites, it is unclear whether any of these potential cholesterol sites are occupied by cholesterol and functionally relevant. In the present study, we focus on the conserved cholesterol site 1 (CHOL1) located in a hydrophobic groove between TM1a, TM5, and TM7. By molecular dynamics simulations, we demonstrate a strong binding of cholesterol to CHOL1 in a membrane bilayer environment. In biochemical experiments, we find that cholesterol depletion induces a more inward-facing conformation favoring substrate analog binding. Consistent with this, we find that mutations in CHOL1 with a negative impact on cholesterol binding induce a more inward-facing conformation, and, vice versa, mutations with a positive impact on cholesterol binding induce a more outward-facing conformation. This shift in transporter conformation dictated by the ability to bind cholesterol in CHOL1 affects the apparent substrate affinity, maximum transport velocity, and turnover rates. Taken together, we show that occupation of CHOL1 by cholesterol is of major importance in the transporter conformational equilibrium, which in turn dictates ligand potency and serotonin transport activity. Based on our findings, we propose a mechanistic model that incorporates the role of cholesterol binding to CHOL1 in the function of SERT.
Collapse
Affiliation(s)
- Louise Laursen
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark and
| | - Kasper Severinsen
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark and
| | - Kristina Birch Kristensen
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark and
| | - Xavier Periole
- the Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Malene Overby
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark and
| | - Heidi Kaastrup Müller
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark and
| | - Birgit Schiøtt
- the Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Steffen Sinning
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark and
| |
Collapse
|
59
|
Chen H, Yu X, Zhang X, Yang L, Huang X, Zhang J, Pritchard HW, Li W. Phospholipase Dα1-mediated phosphatidic acid change is a key determinant of desiccation-induced viability loss in seeds. Plant Cell Environ 2018; 41:50-63. [PMID: 28152567 DOI: 10.1111/pce.12925] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 12/31/2016] [Indexed: 06/06/2023]
Abstract
High sensitivity of seeds to water loss is a widespread phenomenon in the world's plant species. The molecular basis of this trait is poorly understood but thought to be associated with critical changes in membrane function. We profiled membrane lipids of seeds in eight species with varying levels of desiccation tolerance and found a close association between reducing seed viability and increasing phosphatidic acid (PA). We applied hydration-dehydration cycles to Arabidopsis seeds, which are normally desiccation tolerant, to mimic the onset of desiccation sensitivity with progression towards germination and examined the role of phospholipase D (PLD) in desiccation stress-induced production of PA. We found that PLDα1 became more abundant and migrated from the cytosol to the membrane during desiccation, whereas PLDδ did not change, and that all desiccation-induced PA was derived from PLDα1 hydrolysis. When PLDα1 was suppressed, the germination level after each hydration-dehydration cycle improved significantly. We further demonstrated that PLDα1-mediated PA formation modulates desiccation sensitivity as applying its inhibitor improved seed desiccation tolerance and its suppression in protoplasts enhanced survival under dehydration. The insights provided by comparative lipidomics enable us to propose a new membrane-based model for seed desiccation stress and survival.
Collapse
Affiliation(s)
- Hongying Chen
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
| | - Xiaomei Yu
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
| | - Xudong Zhang
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
| | - Lan Yang
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
| | - Xing Huang
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
- Department of Phytopathology, College of Plant Protection, Yunnan Agriculture University, 650201, China
| | - Jie Zhang
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
| | - Hugh W Pritchard
- Royal Botanic Gardens, Kew, Wakehurst Place, West Sussex, RH17 6TN, UK
| | - Weiqi Li
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
| |
Collapse
|
60
|
Qi Y, Liu H, Yu J, Chen X, Liu L. Med15B Regulates Acid Stress Response and Tolerance in Candida glabrata by Altering Membrane Lipid Composition. Appl Environ Microbiol 2017; 83:e01128-17. [PMID: 28710262 DOI: 10.1128/AEM.01128-17] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 07/04/2017] [Indexed: 12/16/2022] Open
Abstract
Candida glabrata is a promising producer of organic acids. To elucidate the physiological function of the Mediator tail subunit Med15B in the response to low-pH stress, we constructed a deletion strain, C. glabratamed15BΔ, and an overexpression strain, C. glabrata HTUΔ/CgMED15B Deletion of MED15B caused biomass production, glucose consumption rate, and cell viability to decrease by 28.3%, 31.7%, and 26.5%, respectively, compared with those of the parent (HTUΔ) strain at pH 2.0. Expression of lipid metabolism-related genes was significantly downregulated in the med15BΔ strain, whereas key genes of ergosterol biosynthesis showed abnormal upregulation. This caused the proportion of C18:1 fatty acids, the ratio of unsaturated to saturated fatty acids (UFA/SFA), and the total phospholipid content to decrease by 11.6%, 27.4%, and 37.6%, respectively. Cells failed to synthesize fecosterol and ergosterol, leading to the accumulation and a 60.3-fold increase in the concentration of zymosterol. Additionally, cells showed reductions of 69.2%, 11.6%, and 21.8% in membrane integrity, fluidity, and H+-ATPase activity, respectively. In contrast, overexpression of Med15B increased the C18:1 levels, total phospholipids, ergosterol content, and UFA/SFA by 18.6%, 143.5%, 94.5%, and 18.7%, respectively. Membrane integrity, fluidity, and H+-ATPase activity also increased by 30.2%, 6.9%, and 51.8%, respectively. Furthermore, in the absence of pH buffering, dry weight of cells and pyruvate concentrations were 29.3% and 61.2% higher, respectively, than those of the parent strain. These results indicated that in C. glabrata, Med15B regulates tolerance toward low pH via transcriptional regulation of acid stress response genes and alteration in lipid composition.IMPORTANCE This study explored the role of the Mediator tail subunit Med15B in the metabolism of Candida glabrata under acidic conditions. Overexpression of MED15B enhanced yeast tolerance to low pH and improved biomass production, cell viability, and pyruvate yield. Membrane lipid composition data indicated that Med15B might play a critical role in membrane integrity, fluidity, and H+-ATPase activity homeostasis at low pH. Thus, controlling membrane composition may serve to increase C. glabrata productivity at low pH.
Collapse
|
61
|
Lin X, Qi Y, Yan D, Liu H, Chen X, Liu L. CgMED3 Changes Membrane Sterol Composition To Help Candida glabrata Tolerate Low-pH Stress. Appl Environ Microbiol 2017; 83:e00972-17. [PMID: 28667115 DOI: 10.1128/AEM.00972-17] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 06/23/2017] [Indexed: 12/11/2022] Open
Abstract
Candida glabrata is a promising microorganism for organic acid production. The present study aimed to investigate the role of C. glabrata Mediator complex subunit 3 (CgMed3p) in protecting C. glabrata under low-pH conditions. To this end, genes CgMED3A and CgMED3B were deleted, resulting in the double-deletion Cgmed3ABΔ strain. The final biomass and cell viability levels of Cgmed3ABΔ decreased by 64.5% and 35.8%, respectively, compared to the wild-type strain results at pH 2.0. In addition, lack of CgMed3ABp resulted in selective repression of a subset of genes in the lipid biosynthesis and metabolism pathways. Furthermore, C18:1, lanosterol, zymosterol, fecosterol, and ergosterol were 13.2%, 80.4%, 40.4%, 78.1%, and 70.4% less abundant, respectively, in the Cgmed3ABΔ strain. In contrast, the concentration of squalene increased by about 44.6-fold. As a result, membrane integrity, rigidity, and H+-ATPase activity in the Cgmed3ABΔ strain were reduced by 62.7%, 13.0%, and 50.3%, respectively. In contrast, overexpression of CgMED3AB increased the levels of C18:0, C18:1, and ergosterol by 113.2%, 5.9%, and 26.4%, respectively. Moreover, compared to the wild-type results, dry cell weight and pyruvate production increased, irrespective of pH buffering. These results suggest that CgMED3AB regulates membrane composition, which in turn enables cells to tolerate low-pH stress. We propose that regulation of CgMed3ABp may provide a novel strategy for enhancing low-pH tolerance and increasing organic acid production by C. glabrataIMPORTANCE The objective of this study was to investigate the role of Candida glabrata Mediator complex subunit 3 (CgMed3ABp) and its regulation of gene expression at low pH in C. glabrata We found that CgMed3ABp was critical for cellular survival and pyruvate production during low-pH stress. Measures of the levels of plasma membrane fatty acids and sterol composition indicated that CgMed3ABp could play an important role in regulating homeostasis in C. glabrata We propose that controlling membrane lipid composition may enhance the robustness of C. glabrata for the production of organic acids.
Collapse
|
62
|
Shindou H, Koso H, Sasaki J, Nakanishi H, Sagara H, Nakagawa KM, Takahashi Y, Hishikawa D, Iizuka-Hishikawa Y, Tokumasu F, Noguchi H, Watanabe S, Sasaki T, Shimizu T. Docosahexaenoic acid preserves visual function by maintaining correct disc morphology in retinal photoreceptor cells. J Biol Chem 2017; 292:12054-12064. [PMID: 28578316 PMCID: PMC5519357 DOI: 10.1074/jbc.m117.790568] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Revised: 06/01/2017] [Indexed: 12/31/2022] Open
Abstract
Docosahexaenoic acid (DHA) has essential roles in photoreceptor cells in the retina and is therefore crucial to healthy vision. Although the influence of dietary DHA on visual acuity is well known and the retina has an abundance of DHA-containing phospholipids (PL-DHA), the mechanisms associated with DHA's effects on visual function are unknown. We previously identified lysophosphatidic acid acyltransferase 3 (LPAAT3) as a PL-DHA biosynthetic enzyme. Here, using comprehensive phospholipid analyses and imaging mass spectroscopy, we found that LPAAT3 is expressed in the inner segment of photoreceptor cells and that PL-DHA disappears from the outer segment in the LPAAT3-knock-out mice. Dynamic light-scattering analysis of liposomes and molecular dynamics simulations revealed that the physical characteristics of DHA reduced membrane-bending rigidity. Following loss of PL-DHA, LPAAT3-knock-out mice exhibited abnormalities in the retinal layers, such as incomplete elongation of the outer segment and decreased thickness of the outer nuclear layers and impaired visual function, as well as disordered disc morphology in photoreceptor cells. Our results indicate that PL-DHA contributes to visual function by maintaining the disc shape in photoreceptor cells and that this is a function of DHA in the retina. This study thus provides the reason why DHA is required for visual acuity and may help inform approaches for overcoming retinal disorders associated with DHA deficiency or dysfunction.
Collapse
Affiliation(s)
- Hideo Shindou
- Department of Lipid Signaling, National Center for Global Health and Medicine, Shinjuku-ku, Tokyo 162-8655; Department of Lipid Science, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033; Agency for Medical Research and Development (AMED)-Core Research for Evolution Science and Technology (CREST), Chiyoda-ku, Tokyo 100-0004.
| | - Hideto Koso
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Shirokanedai, Minato-ku, Tokyo 108-8639
| | - Junko Sasaki
- Department of Medical Biology, Akita University Graduate School of Medicine, Akita 010-8543
| | - Hiroki Nakanishi
- Research Center for Biosignal, Akita University Graduate School of Medicine, Akita 010-8502; Akita Lipid Technologies, LLC, Akita 010-0825
| | - Hiroshi Sagara
- Medical Proteomics Laboratory, Institute of Medical Science, University of Tokyo, Shirokanedai, Minato-ku, Tokyo 108-8639
| | - Koh M Nakagawa
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Yoshikazu Takahashi
- Department of Lipid Signaling, National Center for Global Health and Medicine, Shinjuku-ku, Tokyo 162-8655
| | - Daisuke Hishikawa
- Department of Lipid Signaling, National Center for Global Health and Medicine, Shinjuku-ku, Tokyo 162-8655
| | - Yoshiko Iizuka-Hishikawa
- Department of Lipid Signaling, National Center for Global Health and Medicine, Shinjuku-ku, Tokyo 162-8655
| | - Fuyuki Tokumasu
- Department of Lipidomics, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033
| | - Hiroshi Noguchi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Sumiko Watanabe
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Shirokanedai, Minato-ku, Tokyo 108-8639
| | - Takehiko Sasaki
- Agency for Medical Research and Development (AMED)-Core Research for Evolution Science and Technology (CREST), Chiyoda-ku, Tokyo 100-0004; Department of Medical Biology, Akita University Graduate School of Medicine, Akita 010-8543; Research Center for Biosignal, Akita University Graduate School of Medicine, Akita 010-8502; Akita Lipid Technologies, LLC, Akita 010-0825
| | - Takao Shimizu
- Department of Lipid Signaling, National Center for Global Health and Medicine, Shinjuku-ku, Tokyo 162-8655; Department of Lipidomics, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033
| |
Collapse
|
63
|
Abstract
In the 1970s, phospholipids were still considered mere building blocks of the membrane lipid bilayer, but the subsequent realization that phospholipids could also serve as second messengers brought new interest to the field. My own passion for the unique amphipathic properties of lipids led me to seek other, non-signaling functions for phospholipids, particularly in their interactions with membrane proteins. This seemed to be the last frontier in protein chemistry and enzymology to be conquered. I was fortunate to find my way to Eugene Kennedy's laboratory, where both membrane proteins and phospholipids were the foci of study, thus providing a jumping-off point for advancing our fundamental understanding of lipid synthesis, membrane protein biosynthesis, phospholipid and membrane protein trafficking, and the cellular roles of phospholipids. After purifying and characterizing enzymes of phospholipid biosynthesis in Escherichia coli and cloning of several of the genes encoding these enzymes in E. coli and Saccharomyces cerevisiae, I was in a position to alter phospholipid composition in a systematic manner during the cell cycle in these microorganisms. My group was able to establish, contrary to common assumption (derived from the fact that membrane proteins retain activity in detergent extracts) that phospholipid environment is a strong determining factor in the function of membrane proteins. We showed that molecular genetic alterations in membrane lipid composition result in many phenotypes, and uncovered direct lipid-protein interactions that govern dynamic structural and functional properties of membrane proteins. Here I present my personal "reflections" on how our understanding of phospholipid functions has evolved.
Collapse
Affiliation(s)
- William Dowhan
- From the Department of Biochemistry and Molecular Biology, the University of Texas Health Sciences Center, McGovern Medical School, Houston, Texas 77030
| |
Collapse
|
64
|
Gao Y, Zhou Y, Goldstein JL, Brown MS, Radhakrishnan A. Cholesterol-induced conformational changes in the sterol-sensing domain of the Scap protein suggest feedback mechanism to control cholesterol synthesis. J Biol Chem 2017; 292:8729-8737. [PMID: 28377508 DOI: 10.1074/jbc.m117.783894] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 04/03/2017] [Indexed: 01/28/2023] Open
Abstract
Scap is a polytopic protein of endoplasmic reticulum (ER) membranes that transports sterol regulatory element-binding proteins to the Golgi complex for proteolytic activation. Cholesterol accumulation in ER membranes prevents Scap transport and decreases cholesterol synthesis. Previously, we provided evidence that cholesterol inhibition is initiated when cholesterol binds to loop 1 of Scap, which projects into the ER lumen. Within cells, this binding causes loop 1 to dissociate from loop 7, another luminal Scap loop. However, we have been unable to demonstrate this dissociation when we added cholesterol to isolated complexes of loops 1 and 7. We therefore speculated that the dissociation requires a conformational change in the intervening polytopic sequence separating loops 1 and 7. Here we demonstrate such a change using a protease protection assay in sealed membrane vesicles. In the absence of cholesterol, trypsin or proteinase K cleaved cytosolic loop 4, generating a protected fragment that we visualized with a monoclonal antibody against loop 1. When cholesterol was added to these membranes, cleavage in loop 4 was abolished. Because loop 4 is part of the so-called sterol-sensing domain separating loops 1 and 7, these results support the hypothesis that cholesterol binding to loop 1 alters the conformation of the sterol-sensing domain. They also suggest that this conformational change helps transmit the cholesterol signal from loop 1 to loop 7, thereby allowing separation of the loops and facilitating the feedback inhibition of cholesterol synthesis. These insights suggest a new structural model for cholesterol-mediated regulation of Scap activity.
Collapse
Affiliation(s)
- Yansong Gao
- From the Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Yulian Zhou
- From the Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Joseph L Goldstein
- From the Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Michael S Brown
- From the Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Arun Radhakrishnan
- From the Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| |
Collapse
|
65
|
Van Aelst B, Devloo R, Zachée P, t'Kindt R, Sandra K, Vandekerckhove P, Compernolle V, Feys HB. Psoralen and Ultraviolet A Light Treatment Directly Affects Phosphatidylinositol 3-Kinase Signal Transduction by Altering Plasma Membrane Packing. J Biol Chem 2016; 291:24364-24376. [PMID: 27687726 DOI: 10.1074/jbc.m116.735126] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 09/17/2016] [Indexed: 01/15/2023] Open
Abstract
Psoralen and ultraviolet A light (PUVA) are used to kill pathogens in blood products and as a treatment of aberrant cell proliferation in dermatitis, cutaneous T-cell lymphoma, and graft-versus-host disease. DNA damage is well described, but the direct effects of PUVA on cell signal transduction are poorly understood. Because platelets are anucleate and contain archetypal signal transduction machinery, they are ideally suited to address this. Lipidomics on platelet membrane extracts showed that psoralen forms adducts with unsaturated carbon bonds of fatty acyls in all major phospholipid classes after PUVA. Such adducts increased lipid packing as measured by a blue shift of an environment-sensitive fluorescent probe in model liposomes. Furthermore, the interaction of these liposomes with lipid order-sensitive proteins like amphipathic lipid-packing sensor and α-synuclein was inhibited by PUVA. In platelets, PUVA caused poor membrane binding of Akt and Bruton's tyrosine kinase effectors following activation of the collagen glycoprotein VI and thrombin protease-activated receptor (PAR) 1. This resulted in defective Akt phosphorylation despite unaltered phosphatidylinositol 3,4,5-trisphosphate levels. Downstream integrin activation was furthermore affected similarly by PUVA following PAR1 (effective half-maximal concentration (EC50), 8.4 ± 1.1 versus 4.3 ± 1.1 μm) and glycoprotein VI (EC50, 1.61 ± 0.85 versus 0.26 ± 0.21 μg/ml) but not PAR4 (EC50, 50 ± 1 versus 58 ± 1 μm) signal transduction. Our findings were confirmed in T-cells from graft-versus-host disease patients treated with extracorporeal photopheresis, a form of systemic PUVA. In conclusion, PUVA increases the order of lipid phases by covalent modification of phospholipids, thereby inhibiting membrane recruitment of effector kinases.
Collapse
Affiliation(s)
- Britt Van Aelst
- From the Transfusion Research Center, Belgian Red Cross-Flanders, 9000 Ghent, Belgium
| | - Rosalie Devloo
- From the Transfusion Research Center, Belgian Red Cross-Flanders, 9000 Ghent, Belgium
| | - Pierre Zachée
- the Department of Hematology, Hospital Network Antwerp, 2000 Antwerp, Belgium
| | - Ruben t'Kindt
- the Research Institute for Chromatography, 8500 Kortrijk, Belgium
| | - Koen Sandra
- the Research Institute for Chromatography, 8500 Kortrijk, Belgium
| | - Philippe Vandekerckhove
- the Blood Service of the Belgian Red Cross-Flanders, 2800 Mechelen, Belgium,; the Department of Public Health and Primary Care, KULeuven, 3000 Leuven, Belgium, and; the Faculty of Medicine and Health Sciences, Ghent University, 9000 Ghent, Belgium
| | - Veerle Compernolle
- From the Transfusion Research Center, Belgian Red Cross-Flanders, 9000 Ghent, Belgium,; the Blood Service of the Belgian Red Cross-Flanders, 2800 Mechelen, Belgium,; the Faculty of Medicine and Health Sciences, Ghent University, 9000 Ghent, Belgium
| | - Hendrik B Feys
- From the Transfusion Research Center, Belgian Red Cross-Flanders, 9000 Ghent, Belgium,.
| |
Collapse
|
66
|
Libby AE, Bales E, Orlicky DJ, McManaman JL. Perilipin-2 Deletion Impairs Hepatic Lipid Accumulation by Interfering with Sterol Regulatory Element-binding Protein (SREBP) Activation and Altering the Hepatic Lipidome. J Biol Chem 2016; 291:24231-24246. [PMID: 27679530 DOI: 10.1074/jbc.m116.759795] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Indexed: 12/16/2022] Open
Abstract
Perilipin-2 (PLIN2) is a constitutively associated cytoplasmic lipid droplet coat protein that has been implicated in fatty liver formation in non-alcoholic fatty liver disease. Mice with or without whole-body deletion of perilipin-2 (Plin2-null) were fed either Western or control diets for 30 weeks. Perilipin-2 deletion prevents obesity and insulin resistance in Western diet-fed mice and dramatically reduces hepatic triglyceride and cholesterol levels in mice fed Western or control diets. Gene and protein expression studies reveal that PLIN2 deletion suppressed SREBP-1 and SREBP-2 target genes involved in de novo lipogenesis and cholesterol biosynthetic pathways in livers of mice on either diet. GC-MS lipidomics demonstrate that this reduction correlated with profound alterations in the hepatic lipidome with significant reductions in both desaturation and elongation of hepatic neutral lipid species. To examine the possibility that lipidomic actions of PLIN2 deletion contribute to suppression of SREBP activation, we isolated endoplasmic reticulum membrane fractions from long-term Western diet-fed wild type (WT) and Plin2-null mice. Lipidomic analyses reveal that endoplasmic reticulum membranes from Plin2-null mice are markedly enriched in ω-3 and ω-6 long-chain polyunsaturated fatty acids, which others have shown inhibit SREBP activation and de novo lipogenesis. Our results identify PLIN2 as a determinant of global changes in the hepatic lipidome and suggest the hypothesis that these actions contribute to SREBP-regulated de novo lipogenesis involved in non-alcoholic fatty liver disease.
Collapse
Affiliation(s)
- Andrew E Libby
- From the Integrated Physiology Graduate Program.,Division of Reproductive Sciences, and
| | | | - David J Orlicky
- Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - James L McManaman
- From the Integrated Physiology Graduate Program, .,Division of Reproductive Sciences, and
| |
Collapse
|
67
|
Takar M, Wu Y, Graham TR. The Essential Neo1 Protein from Budding Yeast Plays a Role in Establishing Aminophospholipid Asymmetry of the Plasma Membrane. J Biol Chem 2016; 291:15727-39. [PMID: 27235400 DOI: 10.1074/jbc.m115.686253] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Indexed: 11/06/2022] Open
Abstract
Eukaryotic organisms typically express multiple type IV P-type ATPases (P4-ATPases), which establish plasma membrane asymmetry by flipping specific phospholipids from the exofacial to the cytosolic leaflet. Saccharomyces cerevisiae, for example, expresses five P4-ATPases, including Neo1, Drs2, Dnf1, Dnf2, and Dnf3. Neo1 is thought to be a phospholipid flippase, although there is currently no experimental evidence that Neo1 catalyzes this activity or helps establish membrane asymmetry. Here, we use temperature-conditional alleles (neo1(ts)) to test whether Neo1 deficiency leads to loss of plasma membrane asymmetry. Wild-type (WT) yeast normally restrict most of the phosphatidylserine (PS) and phosphatidylethanolamine (PE) to the inner cytosolic leaflet of the plasma membrane. However, the neo1-1(ts) and neo1-2(ts) mutants display a loss of PS and PE asymmetry at permissive growth temperatures as measured by hypersensitivity to pore-forming toxins that target PS (papuamide A) or PE (duramycin) exposed in the extracellular leaflet. When shifted to a semi-permissive growth temperature, the neo1-1(ts) mutant became extremely hypersensitive to duramycin, although the sensitivity to papuamide A was unchanged, indicating preferential exposure of PE. This loss of asymmetry occurs despite the presence of other flippases that flip PS and/or PE. Even when overexpressed, Drs2 and Dnf1 were unable to correct the loss of asymmetry caused by neo1(ts) However, modest overexpression of Neo1 weakly suppressed loss of membrane asymmetry caused by drs2Δ with a more significant correction of PE asymmetry than PS. These results indicate that Neo1 plays an important role in establishing PS and PE plasma membrane asymmetry in budding yeast.
Collapse
Affiliation(s)
- Mehmet Takar
- From the Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
| | - Yuantai Wu
- From the Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
| | - Todd R Graham
- From the Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
| |
Collapse
|
68
|
Sautrey G, El Khoury M, Dos Santos AG, Zimmermann L, Deleu M, Lins L, Décout JL, Mingeot-Leclercq MP. Negatively Charged Lipids as a Potential Target for New Amphiphilic Aminoglycoside Antibiotics: A BIOPHYSICAL STUDY. J Biol Chem 2016; 291:13864-74. [PMID: 27189936 DOI: 10.1074/jbc.m115.665364] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Indexed: 11/06/2022] Open
Abstract
Bacterial membranes are highly organized, containing specific microdomains that facilitate distinct protein and lipid assemblies. Evidence suggests that cardiolipin molecules segregate into such microdomains, probably conferring a negative curvature to the inner plasma membrane during membrane fission upon cell division. 3',6-Dinonyl neamine is an amphiphilic aminoglycoside derivative active against Pseudomonas aeruginosa, including strains resistant to colistin. The mechanisms involved at the molecular level were identified using lipid models (large unilamellar vesicles, giant unilamelllar vesicles, and lipid monolayers) that mimic the inner membrane of P. aeruginosa The study demonstrated the interaction of 3',6-dinonyl neamine with cardiolipin and phosphatidylglycerol, two negatively charged lipids from inner bacterial membranes. This interaction induced membrane permeabilization and depolarization. Lateral segregation of cardiolipin and membrane hemifusion would be critical for explaining the effects induced on lipid membranes by amphiphilic aminoglycoside antibiotics. The findings contribute to an improved understanding of how amphiphilic aminoglycoside antibiotics that bind to negatively charged lipids like cardiolipin could be promising antibacterial compounds.
Collapse
Affiliation(s)
- Guillaume Sautrey
- From the Université Catholique de Louvain, Louvain Drug Research Institute, Pharmacologie Cellulaire et Moléculaire, Avenue E. Mounier 73, UCL B1.73.05 Bruxelles, Belgium
| | - Micheline El Khoury
- From the Université Catholique de Louvain, Louvain Drug Research Institute, Pharmacologie Cellulaire et Moléculaire, Avenue E. Mounier 73, UCL B1.73.05 Bruxelles, Belgium
| | - Andreia Giro Dos Santos
- From the Université Catholique de Louvain, Louvain Drug Research Institute, Pharmacologie Cellulaire et Moléculaire, Avenue E. Mounier 73, UCL B1.73.05 Bruxelles, Belgium
| | - Louis Zimmermann
- the Département de Pharmacochimie Moléculaire, Université de Grenoble, Alpes/CNRS, UMR 5063, ICMG FR 2607, 470 Rue de la Chimie, BP 53, F-38041 Grenoble, France, and
| | - Magali Deleu
- the Laboratoire de Biophysique Moleculaire aux Interfaces, Université de Liège, Gembloux Agro-Bio Tech, Passage des Déportés, 2, B-5030 Gembloux, Belgium
| | - Laurence Lins
- the Laboratoire de Biophysique Moleculaire aux Interfaces, Université de Liège, Gembloux Agro-Bio Tech, Passage des Déportés, 2, B-5030 Gembloux, Belgium
| | - Jean-Luc Décout
- the Département de Pharmacochimie Moléculaire, Université de Grenoble, Alpes/CNRS, UMR 5063, ICMG FR 2607, 470 Rue de la Chimie, BP 53, F-38041 Grenoble, France, and
| | - Marie-Paule Mingeot-Leclercq
- From the Université Catholique de Louvain, Louvain Drug Research Institute, Pharmacologie Cellulaire et Moléculaire, Avenue E. Mounier 73, UCL B1.73.05 Bruxelles, Belgium,
| |
Collapse
|
69
|
Zhang Y, Lee KM, Kinch LN, Clark L, Grishin NV, Rosenbaum DM, Brown MS, Goldstein JL, Radhakrishnan A. Direct Demonstration That Loop1 of Scap Binds to Loop7: A CRUCIAL EVENT IN CHOLESTEROL HOMEOSTASIS. J Biol Chem 2016; 291:12888-12896. [PMID: 27068746 DOI: 10.1074/jbc.m116.729798] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Indexed: 11/06/2022] Open
Abstract
Cholesterol homeostasis is mediated by Scap, a polytopic endoplasmic reticulum (ER) protein that transports sterol regulatory element-binding proteins from the ER to Golgi, where they are processed to forms that activate cholesterol synthesis. Scap has eight transmembrane helices and two large luminal loops, designated Loop1 and Loop7. We earlier provided indirect evidence that Loop1 binds to Loop7, allowing Scap to bind COPII proteins for transport in coated vesicles. When ER cholesterol rises, it binds to Loop1. We hypothesized that this causes dissociation from Loop7, abrogating COPII binding. Here we demonstrate direct binding of the two loops when expressed as isolated fragments or as a fusion protein. Expressed alone, Loop1 remained intracellular and membrane-bound. When Loop7 was co-expressed, it bound to Loop1, and the soluble complex was secreted. A Loop1-Loop7 fusion protein was also secreted, and the two loops remained bound when the linker between them was cleaved by a protease. Point mutations that disrupt the Loop1-Loop7 interaction prevented secretion of the Loop1-Loop7 fusion protein. These data provide direct documentation of intramolecular Loop1-Loop7 binding, a central event in cholesterol homeostasis.
Collapse
Affiliation(s)
| | | | - Lisa N Kinch
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | | | - Nick V Grishin
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Biophysics, and; Biochemistry and
| | | | | | | | | |
Collapse
|
70
|
Uesono Y, Toh-e A, Kikuchi Y, Araki T, Hachiya T, Watanabe CK, Noguchi K, Terashima I. Local Anesthetics and Antipsychotic Phenothiazines Interact Nonspecifically with Membranes and Inhibit Hexose Transporters in Yeast. Genetics 2016; 202:997-1012. [PMID: 26757771 PMCID: PMC4788134 DOI: 10.1534/genetics.115.183806] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 12/30/2015] [Indexed: 01/04/2023] Open
Abstract
Action mechanisms of anesthetics remain unclear because of difficulty in explaining how structurally different anesthetics cause similar effects. In Saccharomyces cerevisiae, local anesthetics and antipsychotic phenothiazines induced responses similar to those caused by glucose starvation, and they eventually inhibited cell growth. These drugs inhibited glucose uptake, but additional glucose conferred resistance to their effects; hence, the primary action of the drugs is to cause glucose starvation. In hxt(0) strains with all hexose transporter (HXT) genes deleted, a strain harboring a single copy of HXT1 (HXT1s) was more sensitive to tetracaine than a strain harboring multiple copies (HXT1m), which indicates that quantitative reduction of HXT1 increases tetracaine sensitivity. However, additional glucose rather than the overexpression of HXT1/2 conferred tetracaine resistance to wild-type yeast; therefore, Hxts that actively transport hexoses apparently confer tetracaine resistance. Additional glucose alleviated sensitivity to local anesthetics and phenothiazines in the HXT1m strain but not the HXT1s strain; thus, the glucose-induced effects required a certain amount of Hxt1. At low concentrations, fluorescent phenothiazines were distributed in various membranes. At higher concentrations, they destroyed the membranes and thereby delocalized Hxt1-GFP from the plasma membrane, similar to local anesthetics. These results suggest that the aforementioned drugs affect various membrane targets via nonspecific interactions with membranes. However, the drugs preferentially inhibit the function of abundant Hxts, resulting in glucose starvation. When Hxts are scarce, this preference is lost, thereby mitigating the alleviation by additional glucose. These results provide a mechanism that explains how different compounds induce similar effects based on lipid theory.
Collapse
Affiliation(s)
- Yukifumi Uesono
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 113-0033 Japan
| | - Akio Toh-e
- Medical Mycology Research Center (MMRC), Chiba University, Chiba, 260-8673 Japan
| | - Yoshiko Kikuchi
- Department of Life Science, Gakushuin University, Tokyo, 171-8588 Japan
| | - Tomoyuki Araki
- Department of Molecular Biology, Saitama Medical University, Saitama, 350-0495 Japan
| | - Takushi Hachiya
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 113-0033 Japan
| | - Chihiro K Watanabe
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 113-0033 Japan
| | - Ko Noguchi
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Tokyo, 192-0392 Japan
| | - Ichiro Terashima
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 113-0033 Japan
| |
Collapse
|
71
|
Dawaliby R, Trubbia C, Delporte C, Noyon C, Ruysschaert JM, Van Antwerpen P, Govaerts C. Phosphatidylethanolamine Is a Key Regulator of Membrane Fluidity in Eukaryotic Cells. J Biol Chem 2015; 291:3658-67. [PMID: 26663081 DOI: 10.1074/jbc.m115.706523] [Citation(s) in RCA: 220] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Indexed: 01/10/2023] Open
Abstract
Adequate membrane fluidity is required for a variety of key cellular processes and in particular for proper function of membrane proteins. In most eukaryotic cells, membrane fluidity is known to be regulated by fatty acid desaturation and cholesterol, although some cells, such as insect cells, are almost devoid of sterol synthesis. We show here that insect and mammalian cells present similar microviscosity at their respective physiological temperature. To investigate how both sterols and phospholipids control fluidity homeostasis, we quantified the lipidic composition of insect SF9 and mammalian HEK 293T cells under normal or sterol-modified condition. As expected, insect cells show minimal sterols compared with mammalian cells. A major difference is also observed in phospholipid content as the ratio of phosphatidylethanolamine (PE) to phosphatidylcholine (PC) is inverted (4 times higher in SF9 cells). In vitro studies in liposomes confirm that both cholesterol and PE can increase rigidity of the bilayer, suggesting that both can be used by cells to maintain membrane fluidity. We then show that exogenously increasing the cholesterol amount in SF9 membranes leads to a significant decrease in PE:PC ratio whereas decreasing cholesterol in HEK 293T cells using statin treatment leads to an increase in the PE:PC ratio. In all cases, the membrane fluidity is maintained, indicating that both cell types combine regulation by sterols and phospholipids to control proper membrane fluidity.
Collapse
Affiliation(s)
- Rosie Dawaliby
- From the Laboratory for the Structure and Function of Biological Membranes, Center for Structural Biology and Bioinformatics, Université Libre de Bruxelles, CP 206/02, Bd du Triomphe, 1050 Brussels, Belgium
| | - Cataldo Trubbia
- From the Laboratory for the Structure and Function of Biological Membranes, Center for Structural Biology and Bioinformatics, Université Libre de Bruxelles, CP 206/02, Bd du Triomphe, 1050 Brussels, Belgium
| | - Cédric Delporte
- Laboratory of Pharmaceutical Chemistry and Analytical Platform of the Faculty of Pharmacy, Faculty of Pharmacy, Université Libre de Bruxelles, 1050 Brussels, Belgium
| | - Caroline Noyon
- Laboratory of Pharmaceutical Chemistry and Analytical Platform of the Faculty of Pharmacy, Faculty of Pharmacy, Université Libre de Bruxelles, 1050 Brussels, Belgium
| | - Jean-Marie Ruysschaert
- From the Laboratory for the Structure and Function of Biological Membranes, Center for Structural Biology and Bioinformatics, Université Libre de Bruxelles, CP 206/02, Bd du Triomphe, 1050 Brussels, Belgium
| | - Pierre Van Antwerpen
- Laboratory of Pharmaceutical Chemistry and Analytical Platform of the Faculty of Pharmacy, Faculty of Pharmacy, Université Libre de Bruxelles, 1050 Brussels, Belgium
| | - Cédric Govaerts
- From the Laboratory for the Structure and Function of Biological Membranes, Center for Structural Biology and Bioinformatics, Université Libre de Bruxelles, CP 206/02, Bd du Triomphe, 1050 Brussels, Belgium,
| |
Collapse
|
72
|
Güler G, Gärtner RM, Ziegler C, Mäntele W. Lipid-Protein Interactions in the Regulated Betaine Symporter BetP Probed by Infrared Spectroscopy. J Biol Chem 2015; 291:4295-307. [PMID: 26592930 DOI: 10.1074/jbc.m114.621979] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Indexed: 11/06/2022] Open
Abstract
The Na(+)-coupled betaine symporter BetP senses changes in the membrane state and increasing levels of cytoplasmic K(+) during hyperosmotic stress latter via its C-terminal domain and regulates transport activity according to both stimuli. This intriguing sensing and regulation behavior of BetP was intensively studied in the past. It was shown by several biochemical studies that activation and regulation depends crucially on the lipid composition of the surrounding membrane. In fact, BetP is active and regulated only when negatively charged lipids are present. Recent structural studies have revealed binding of phosphatidylglycerol lipids to functional important parts of BetP, suggesting a functional role of lipid interactions. However, a regulatory role of lipid interactions could only be speculated from the snapshot provided by the crystal structure. Here, we investigate the nature of lipid-protein interactions of BetP reconstituted in closely packed two-dimensional crystals of negatively charged lipids and probed at the molecular level with Fourier transform infrared (FTIR) spectroscopy. The FTIR data indicate that K(+) binding weakens the interaction of BetP especially with the anionic lipid head groups. We suggest a regulation mechanism in which lipid-protein interactions, especially with the C-terminal domain and the functional important gating helices transmembrane helice 3 (TMH3) and TMH12, confine BetP to its down-regulated transport state. As BetP is also activated by changes in the physical state of the membrane, our results point toward a more general mechanism of how active transport can be modified by dynamic lipid-protein interactions.
Collapse
Affiliation(s)
- Günnur Güler
- From the Goethe-University, Institute of Biophysics, Max-von-Laue-Strasse 1, D-60438, Frankfurt am Main, Germany
| | - Rebecca M Gärtner
- Max Planck Institute of Biophysics, Department of Structural Biology, Max-von-Laue-Strasse 3, D-60438, Frankfurt am Main, Germany, and
| | - Christine Ziegler
- Max Planck Institute of Biophysics, Department of Structural Biology, Max-von-Laue-Strasse 3, D-60438, Frankfurt am Main, Germany, and University of Regensburg, Faculty of Biology and Preclinical Medicine, Universitätsstrasse 31, D-93051, Regensburg, Germany
| | - Werner Mäntele
- From the Goethe-University, Institute of Biophysics, Max-von-Laue-Strasse 1, D-60438, Frankfurt am Main, Germany,
| |
Collapse
|
73
|
Ji C, Zhang Y, Xu P, Xu T, Lou X. Nanoscale Landscape of Phosphoinositides Revealed by Specific Pleckstrin Homology (PH) Domains Using Single-molecule Superresolution Imaging in the Plasma Membrane. J Biol Chem 2015; 290:26978-26993. [PMID: 26396197 DOI: 10.1074/jbc.m115.663013] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Indexed: 11/06/2022] Open
Abstract
Both phosphatidylinositol 4-phosphate (PI4P) and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) are independent plasma membrane (PM) determinant lipids that are essential for multiple cellular functions. However, their nanoscale spatial organization in the PM remains elusive. Using single-molecule superresolution microscopy and new photoactivatable fluorescence probes on the basis of pleckstrin homology domains that specifically recognize phosphatidylinositides in insulin-secreting INS-1 cells, we report that the PI(4,5)P2 probes exhibited a remarkably uniform distribution in the major regions of the PM, with some sparse PI(4,5)P2-enriched membrane patches/domains of diverse sizes (383 ± 14 nm on average). Quantitative analysis revealed a modest concentration gradient that was much less steep than previously thought, and no densely packed PI(4,5)P2 nanodomains were observed. Live-cell superresolution imaging further demonstrated the dynamic structural changes of those domains in the flat PM and membrane protrusions. PI4P and phosphatidylinositol (3,4,5)-trisphosphate (PI(3,4,5)P3) showed similar spatial distributions as PI(4,5)P2. These data reveal the nanoscale landscape of key inositol phospholipids in the native PM and imply a framework for local cellular signaling and lipid-protein interactions at a nanometer scale.
Collapse
Affiliation(s)
- Chen Ji
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705 and
| | - Yongdeng Zhang
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Pingyong Xu
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Tao Xu
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xuelin Lou
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705 and.
| |
Collapse
|
74
|
Abstract
Diabetes mellitus is associated with a variety of complications, including alterations in the central nervous system (CNS). We have recently shown that diabetes results in a reduction of cholesterol synthesis in the brain due to decreased insulin stimulation of SREBP2-mediated cholesterol synthesis in neuronal and glial cells. In the present study, we explored the effects of the decrease in cholesterol on neuronal cell function using GT1-7 hypothalamic cells subjected to cholesterol depletion in vitro using three independent methods: 1) exposure to methyl-β-cyclodextrin, 2) treatment with the HMG-CoA reductase inhibitor simvastatin, and 3) shRNA-mediated knockdown of SREBP2. All three methods produced 20-31% reductions in cellular cholesterol content, similar to the decrease in cholesterol synthesis observed in diabetes. All cholesterol-depleted neuron-derived cells, independent of the method of reduction, exhibited decreased phosphorylation/activation of IRS-1 and AKT following stimulation by insulin, insulin-like growth factor-1, or the neurotrophins (NGF and BDNF). ERK phosphorylation/activation was also decreased after methyl-β-cyclodextrin and statin treatment but increased in cells following SREBP2 knockdown. In addition, apoptosis in the presence of amyloid-β was increased. Reduction in cellular cholesterol also resulted in increased basal autophagy and impairment of induction of autophagy by glucose deprivation. Together, these data indicate that a reduction in neuron-derived cholesterol content, similar to that observed in diabetic brain, creates a state of insulin and growth factor resistance that could contribute to CNS-related complications of diabetes, including increased risk of neurodegenerative diseases, such as Alzheimer disease.
Collapse
Affiliation(s)
- Kenji Fukui
- From the Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts 02215
| | - Heather A Ferris
- From the Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts 02215
| | - C Ronald Kahn
- From the Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts 02215
| |
Collapse
|
75
|
Aleidi SM, Howe V, Sharpe LJ, Yang A, Rao G, Brown AJ, Gelissen IC. The E3 ubiquitin ligases, HUWE1 and NEDD4-1, are involved in the post-translational regulation of the ABCG1 and ABCG4 lipid transporters. J Biol Chem 2015; 290:24604-13. [PMID: 26296893 DOI: 10.1074/jbc.m115.675579] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Indexed: 11/06/2022] Open
Abstract
The ATP-binding cassette transporter ABCG1 has an essential role in cellular cholesterol homeostasis, and dysregulation has been associated with a number of high burden diseases. Previous studies reported that ABCG1 is ubiquitinated and degraded via the ubiquitin proteasome system. However, so far the molecular mechanism, including the identity of any of the rate-limiting ubiquitination enzymes, or E3 ligases, is unknown. Using liquid chromatography mass spectrometry, we identified two HECT domain E3 ligases associated with ABCG1, named HUWE1 (HECT, UBA, and WWE domain containing 1, E3 ubiquitin protein ligase) and NEDD4-1 (Neural precursor cell-expressed developmentally down regulated gene 4), of which the latter is the founding member of the NEDD4 family of ubiquitin ligases. Silencing both HUWE1 and NEDD4-1 in cells overexpressing human ABCG1 significantly increased levels of the ABCG1 monomeric and dimeric protein forms, however ABCA1 protein expression was unaffected. In addition, ligase silencing increased ABCG1-mediated cholesterol export to HDL in cells overexpressing the transporter as well as in THP-1 macrophages. Reciprocally, overexpression of both ligases resulted in a significant reduction in protein levels of both the ABCG1 monomeric and dimeric forms. Like ABCG1, ABCG4 protein levels and cholesterol export activity were significantly increased after silencing both HUWE1 and NEDD4-1 in cells overexpressing this closely related ABC half-transporter. In summary, we have identified for the first time two E3 ligases that are fundamental enzymes in the post-translational regulation of ABCG1 and ABCG4 protein levels and cellular cholesterol export activity.
Collapse
Affiliation(s)
- Shereen M Aleidi
- From the Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006 and
| | - Vicky Howe
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney NSW 2052 Australia
| | - Laura J Sharpe
- From the Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006 and School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney NSW 2052 Australia
| | - Alryel Yang
- From the Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006 and
| | - Geetha Rao
- From the Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006 and
| | - Andrew J Brown
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney NSW 2052 Australia
| | - Ingrid C Gelissen
- From the Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006 and
| |
Collapse
|
76
|
Zeitler M, Steringer JP, Müller HM, Mayer MP, Nickel W. HIV-Tat Protein Forms Phosphoinositide-dependent Membrane Pores Implicated in Unconventional Protein Secretion. J Biol Chem 2015; 290:21976-84. [PMID: 26183781 DOI: 10.1074/jbc.m115.667097] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Indexed: 12/20/2022] Open
Abstract
HIV-Tat has been demonstrated to be secreted from cells in a phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2)-dependent manner. Here we show that HIV-Tat forms membrane-inserted oligomers, a process that is accompanied by changes in secondary structure with a strong increase in antiparallel β sheet content. Intriguingly, oligomerization of HIV-Tat on membrane surfaces leads to the formation of membrane pores, as demonstrated by physical membrane passage of small fluorescent tracer molecules. Although membrane binding of HIV-Tat did not strictly depend on PI(4,5)P2 but, rather, was mediated by a range of acidic membrane lipids, a functional interaction between PI(4,5)P2 and HIV-Tat was critically required for efficient membrane pore formation by HIV-Tat oligomers. These properties are strikingly similar to what has been reported previously for fibroblast growth factor 2 (FGF2), providing strong evidence of a common core mechanism of unconventional secretion shared by HIV-Tat and fibroblast growth factor 2.
Collapse
Affiliation(s)
- Marcel Zeitler
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany and
| | - Julia P Steringer
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany and
| | - Hans-Michael Müller
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany and
| | - Matthias P Mayer
- the Zentrum für Molekulare Biologie der Universität Heidelberg, Deutsches Krebsforschungszentrum-Zentrum für Molekulare Biologie der Universität Heidelberg Allianz, 69120 Heidelberg, Germany
| | - Walter Nickel
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany and
| |
Collapse
|
77
|
Farrand AJ, Hotze EM, Sato TK, Wade KR, Wimley WC, Johnson AE, Tweten RK. The Cholesterol-dependent Cytolysin Membrane-binding Interface Discriminates Lipid Environments of Cholesterol to Support β-Barrel Pore Insertion. J Biol Chem 2015; 290:17733-17744. [PMID: 26032415 DOI: 10.1074/jbc.m115.656769] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Indexed: 12/25/2022] Open
Abstract
The majority of cholesterol-dependent cytolysins (CDCs) utilize cholesterol as a membrane receptor, whereas a small number are restricted to the GPI-anchored protein CD59 for initial membrane recognition. Two cholesterol-binding CDCs, perfringolysin O (PFO) and streptolysin O (SLO), were found to exhibit strikingly different binding properties to cholesterol-rich natural and synthetic membranes. The structural basis for this difference was mapped to one of the loops (L3) in the membrane binding interface that help anchor the toxin monomers to the membrane after receptor (cholesterol) binding by the membrane insertion of its amino acid side chains. A single point mutation in this loop conferred the binding properties of SLO to PFO and vice versa. Our studies strongly suggest that changing the side chain structure of this loop alters its equilibrium between membrane-inserted and uninserted states, thereby affecting the overall binding affinity and total bound toxin. Previous studies have shown that the lipid environment of cholesterol has a dramatic effect on binding and activity. Combining this data with the results of our current studies on L3 suggests that the structure of this loop has evolved in the different CDCs to preferentially direct binding to cholesterol in different lipid environments. Finally, the efficiency of β-barrel pore formation was inversely correlated with the increased binding and affinity of the PFO L3 mutant, suggesting that selection of a compatible lipid environment impacts the efficiency of membrane insertion of the β-barrel pore.
Collapse
Affiliation(s)
- Allison J Farrand
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Eileen M Hotze
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Takehiro K Sato
- Departments of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas 77843
| | - Kristin R Wade
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - William C Wimley
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, Louisiana 70112
| | - Arthur E Johnson
- Departments of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas 77843; Departments of Chemistry and Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - Rodney K Tweten
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
| |
Collapse
|
78
|
Escobedo-Hinojosa WI, Vences-Guzmán MÁ, Schubotz F, Sandoval-Calderón M, Summons RE, López-Lara IM, Geiger O, Sohlenkamp C. OlsG (Sinac_1600) Is an Ornithine Lipid N-Methyltransferase from the Planctomycete Singulisphaera acidiphila. J Biol Chem 2015; 290:15102-11. [PMID: 25925947 DOI: 10.1074/jbc.m115.639575] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Indexed: 11/06/2022] Open
Abstract
Ornithine lipids (OLs) are phosphorus-free membrane lipids widespread in bacteria but absent from archaea and eukaryotes. In addition to the unmodified OLs, a variety of OL derivatives hydroxylated in different structural positions has been reported. Recently, methylated derivatives of OLs were described in several planctomycetes isolated from a peat bog in Northern Russia, although the gene/enzyme responsible for the N-methylation of OL remained obscure. Here we identify and characterize the OL N-methyltransferase OlsG (Sinac_1600) from the planctomycete Singulisphaera acidiphila. When OlsG is co-expressed with the OL synthase OlsF in Escherichia coli, methylated OL derivatives are formed. An in vitro characterization shows that OlsG is responsible for the 3-fold methylation of the terminal δ-nitrogen of OL. Methylation is dependent on the presence of the detergent Triton X-100 and the methyldonor S-adenosylmethionine.
Collapse
Affiliation(s)
- Wendy Itzel Escobedo-Hinojosa
- From the Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos CP62210, Mexico and
| | - Miguel Ángel Vences-Guzmán
- From the Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos CP62210, Mexico and
| | - Florence Schubotz
- the Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02144
| | - Mario Sandoval-Calderón
- From the Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos CP62210, Mexico and
| | - Roger E Summons
- the Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02144
| | - Isabel María López-Lara
- From the Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos CP62210, Mexico and
| | - Otto Geiger
- From the Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos CP62210, Mexico and
| | - Christian Sohlenkamp
- From the Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos CP62210, Mexico and
| |
Collapse
|
79
|
Hwang HH, Gelvin SB, Lai EM. Editorial: "Agrobacterium biology and its application to transgenic plant production". Front Plant Sci 2015; 6:265. [PMID: 25954291 PMCID: PMC4406079 DOI: 10.3389/fpls.2015.00265] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 04/02/2015] [Indexed: 05/15/2023]
Affiliation(s)
- Hau-Hsuan Hwang
- Department of Life Sciences, National Chung Hsing UniversityTaichung, Taiwan
- *Correspondence: Hau-Hsuan Hwang,
| | - Stanton B. Gelvin
- Department of Biological Sciences, Purdue UniversityWest Lafayette, IN, USA
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia SinicaTaipei, Taiwan
| |
Collapse
|
80
|
Wolfenden J, Wellburn AR. Effects of summer ozone on membrane lipid composition during subsequent frost hardening in Norway spruce [Picea abies (L.) Karst]. New Phytol 1991; 118:323-329. [PMID: 33874181 DOI: 10.1111/j.1469-8137.1991.tb00984.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Norway spruce trees [Picea abies (L.) Karst] were exposed to ozone during the summers of three consecutive years and the fatty acid composition of the chloroplast membrane lipid, monogalactosyl diglyceride (MCDG) was analysed over the last 14 months. Significant variations in the degree of unsaturation and the percentage of linolenic acid (18:3) were not found, either on a seasonal basis or in relation to ozone treatment. The proportion of octadecatetraenoic acid (18:4) and other Δ5 fatty acids increased during autumn in trees grown in filtered air, but this seasonal effect was less pronounced in ozone-treated trees. The ratio of two forms of linoleate, Δ5,9 18:2 and Δ9,12 18:2 also increased significantly during the frost hardening period but not in trees previously exposed to ozone. This implies that two separate biosynthetic pathways exist, one for the Δ12 and one for the Δ12 desaturated series, which operate at different relative rates, depending on environmental conditions. It is suggested that ozone may interfere with the biosynthesis of 18:4 during frost hardening by inhibiting the Δ5 desaturation of oleate.
Collapse
Affiliation(s)
- J Wolfenden
- Division of Biological Sciences, Institute of Environmental & Biological Sciences, Lancaster University, Lancaster, LAI 4YQ
| | - A R Wellburn
- Division of Biological Sciences, Institute of Environmental & Biological Sciences, Lancaster University, Lancaster, LAI 4YQ
| |
Collapse
|