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Srinivasan S, Di Luca A, Álvarez D, John Peter AT, Gehin C, Lone MA, Hornemann T, D’Angelo G, Vanni S. The conformational plasticity of structurally unrelated lipid transport proteins correlates with their mode of action. PLoS Biol 2024; 22:e3002737. [PMID: 39159271 PMCID: PMC11361750 DOI: 10.1371/journal.pbio.3002737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 08/29/2024] [Accepted: 07/05/2024] [Indexed: 08/21/2024] Open
Abstract
Lipid transfer proteins (LTPs) are key players in cellular homeostasis and regulation, as they coordinate the exchange of lipids between different cellular organelles. Despite their importance, our mechanistic understanding of how LTPs function at the molecular level is still in its infancy, mostly due to the large number of existing LTPs and to the low degree of conservation at the sequence and structural level. In this work, we use molecular simulations to characterize a representative dataset of lipid transport domains (LTDs) of 12 LTPs that belong to 8 distinct families. We find that despite no sequence homology nor structural conservation, the conformational landscape of LTDs displays common features, characterized by the presence of at least 2 main conformations whose populations are modulated by the presence of the bound lipid. These conformational properties correlate with their mechanistic mode of action, allowing for the interpretation and design of experimental strategies to further dissect their mechanism. Our findings indicate the existence of a conserved, fold-independent mechanism of lipid transfer across LTPs of various families and offer a general framework for understanding their functional mechanism.
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Affiliation(s)
| | - Andrea Di Luca
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Daniel Álvarez
- Department of Biology, University of Fribourg, Fribourg, Switzerland
- Departamento de Química Física y Analítica, Universidad de Oviedo, Oviedo, Spain
| | | | - Charlotte Gehin
- Institute of Bioengineering (IBI) and Global Heath Institute (GHI), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Museer A. Lone
- Institute of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Thorsten Hornemann
- Institute of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Giovanni D’Angelo
- Institute of Bioengineering (IBI) and Global Heath Institute (GHI), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Stefano Vanni
- Department of Biology, University of Fribourg, Fribourg, Switzerland
- National Center of Competence in Research Bio-inspired Materials, University of Fribourg, Fribourg, Switzerland
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2
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Wilson S, Panagabko C, Laleye T, Robinson M, Jagas S, Bowman D, Atkinson J. Synthesis of a photocleavable bola-phosphatidylcholine. Bioorg Med Chem 2023; 93:117465. [PMID: 37688997 DOI: 10.1016/j.bmc.2023.117465] [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] [Received: 06/01/2023] [Revised: 09/01/2023] [Accepted: 09/02/2023] [Indexed: 09/11/2023]
Abstract
Phosphatidylinositol transfer proteins (PITPs) are ubiquitous in eukaryotes and are involved in the regulation of phospholipid metabolism, membrane trafficking, and signal transduction. Sec14 is a yeast PITP that has been shown to transfer phosphatidylinositol (PI) or phosphatidylcholine (PC) from the endoplasmic reticulum to the Golgi. It is now believed that Sec14 may play a greater role than just shuttling PI and PC throughout the cell. Genetic evidence suggests that retrieval of membrane-bound PI by Sec14 also manages to present PI to the phosphatidylinositol-4-kinase, Pik1, to generate phosphatidylinositol-4-phosphate, PI(4)P. To test this hypothetical model, we designed a photocleavable bolalipid to span the entire membrane, having one phosphatidylcholine or phosphatidylinositol headgroup on each leaflet connected by a photocleavable diacid. Sec14 should not be able to present the bola-PI to Pik1 for phosphorylation as the head group will be difficult to lift from the bilayer as it is tethered on the opposite leaflet. After photocleavage the two halves would behave as a normal phospholipid, thus phosphorylation by Pik1 would resume. We report here the synthesis of a photocleavable bola-PC, a precursor to the desired bola-PI. The mono-photocleavable bola-PC lipid was designed to contain two glycerol molecules with choline head groups connected through a phosphodiester bond at the sn3 position. Each glycerol was acylated with palmitic acid at the sn1 position. These two glycerol moieties were then connected through their respective sn2 hydroxyls via a photocleavable dicarboxylic acid containing a nitrophenyl ethyl photolabile protecting group. The bola-PC and its precursors were found to undergo efficient photocleavage when irradiated in solution or in vesicles with 365 nm light for two minutes. Treatment of the bola-PC with a mutant phospholipase D and myo-inositol produced a mono-inositol bola-PC-PI.
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Affiliation(s)
- Sean Wilson
- Department of Chemistry, Brock University, Ontario, Canada
| | | | - Tayo Laleye
- Department of Chemistry, Brock University, Ontario, Canada
| | | | - Samuel Jagas
- Department of Chemistry, Brock University, Ontario, Canada
| | - David Bowman
- Advanced Biomanufacturing Centre, Brock University, Ontario, Canada
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3
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Montag K, Ivanov R, Bauer P. Role of SEC14-like phosphatidylinositol transfer proteins in membrane identity and dynamics. FRONTIERS IN PLANT SCIENCE 2023; 14:1181031. [PMID: 37255567 PMCID: PMC10225987 DOI: 10.3389/fpls.2023.1181031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 04/05/2023] [Indexed: 06/01/2023]
Abstract
Membrane identity and dynamic processes, that act at membrane sites, provide important cues for regulating transport, signal transduction and communication across membranes. There are still numerous open questions as to how membrane identity changes and the dynamic processes acting at the surface of membranes are regulated in diverse eukaryotes in particular plants and which roles are being played by protein interaction complexes composed of peripheral and integral membrane proteins. One class of peripheral membrane proteins conserved across eukaryotes comprises the SEC14-like phosphatidylinositol transfer proteins (SEC14L-PITPs). These proteins share a SEC14 domain that contributes to membrane identity and fulfills regulatory functions in membrane trafficking by its ability to sense, bind, transport and exchange lipophilic substances between membranes, such as phosphoinositides and diverse other lipophilic substances. SEC14L-PITPs can occur as single-domain SEC14-only proteins in all investigated organisms or with a modular domain structure as multi-domain proteins in animals and streptophytes (comprising charales and land plants). Here, we present an overview on the functional roles of SEC14L-PITPs, with a special focus on the multi-domain SEC14L-PITPs of the SEC14-nodulin and SEC14-GOLD group (PATELLINs, PATLs in plants). This indicates that SEC14L-PITPs play diverse roles from membrane trafficking to organism fitness in plants. We concentrate on the structure of SEC14L-PITPs, their ability to not only bind phospholipids but also other lipophilic ligands, and their ability to regulate complex cellular responses through interacting with proteins at membrane sites.
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Affiliation(s)
- Karolin Montag
- Institute of Botany, Heinrich Heine University, Düsseldorf, Germany
| | - Rumen Ivanov
- Institute of Botany, Heinrich Heine University, Düsseldorf, Germany
| | - Petra Bauer
- Institute of Botany, Heinrich Heine University, Düsseldorf, Germany
- Center of Excellence on Plant Sciences (CEPLAS), Germany
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4
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Chen XR, Poudel L, Hong Z, Johnen P, Katti S, Tripathi A, Nile AH, Green SM, Khan D, Schaaf G, Bono F, Bankaitis VA, Igumenova TI. Mechanisms by which small molecules of diverse chemotypes arrest Sec14 lipid transfer activity. J Biol Chem 2023; 299:102861. [PMID: 36603766 PMCID: PMC9898755 DOI: 10.1016/j.jbc.2022.102861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 12/27/2022] [Accepted: 12/28/2022] [Indexed: 01/04/2023] Open
Abstract
Phosphatidylinositol (PtdIns) transfer proteins (PITPs) enhance the activities of PtdIns 4-OH kinases that generate signaling pools of PtdIns-4-phosphate. In that capacity, PITPs serve as key regulators of lipid signaling in eukaryotic cells. Although the PITP phospholipid exchange cycle is the engine that stimulates PtdIns 4-OH kinase activities, the underlying mechanism is not understood. Herein, we apply an integrative structural biology approach to investigate interactions of the yeast PITP Sec14 with small-molecule inhibitors (SMIs) of its phospholipid exchange cycle. Using a combination of X-ray crystallography, solution NMR spectroscopy, and atomistic MD simulations, we dissect how SMIs compete with native Sec14 phospholipid ligands and arrest phospholipid exchange. Moreover, as Sec14 PITPs represent new targets for the development of next-generation antifungal drugs, the structures of Sec14 bound to SMIs of diverse chemotypes reported in this study will provide critical information required for future structure-based design of next-generation lead compounds directed against Sec14 PITPs of virulent fungi.
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Affiliation(s)
- Xiao-Ru Chen
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas USA
| | - Lokendra Poudel
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas USA
| | - Zebin Hong
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Philipp Johnen
- Institute for Crop Science and Resource Conservation, Universität Bonn, Bonn, Germany
| | - Sachin Katti
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas USA
| | - Ashutosh Tripathi
- Department of Cell Biology & Genetics, Texas A&M University, College Station, Texas, USA
| | - Aaron H Nile
- Department of Cell Biology & Genetics, Texas A&M University, College Station, Texas, USA
| | - Savana M Green
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas USA; Department of Cell Biology & Genetics, Texas A&M University, College Station, Texas, USA
| | - Danish Khan
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas USA
| | - Gabriel Schaaf
- Institute for Crop Science and Resource Conservation, Universität Bonn, Bonn, Germany
| | - Fulvia Bono
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Vytas A Bankaitis
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas USA; Department of Cell Biology & Genetics, Texas A&M University, College Station, Texas, USA.
| | - Tatyana I Igumenova
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas USA.
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5
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Zouiouich M, Di Mattia T, Martinet A, Eichler J, Wendling C, Tomishige N, Grandgirard E, Fuggetta N, Fromental-Ramain C, Mizzon G, Dumesnil C, Carpentier M, Reina-San-Martin B, Mathelin C, Schwab Y, Thiam AR, Kobayashi T, Drin G, Tomasetto C, Alpy F. MOSPD2 is an endoplasmic reticulum-lipid droplet tether functioning in LD homeostasis. J Cell Biol 2022; 221:e202110044. [PMID: 35389430 PMCID: PMC8996327 DOI: 10.1083/jcb.202110044] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 02/11/2022] [Accepted: 03/16/2022] [Indexed: 12/28/2022] Open
Abstract
Membrane contact sites between organelles are organized by protein bridges. Among the components of these contacts, the VAP family comprises ER-anchored proteins, such as MOSPD2, that function as major ER-organelle tethers. MOSPD2 distinguishes itself from the other members of the VAP family by the presence of a CRAL-TRIO domain. In this study, we show that MOSPD2 forms ER-lipid droplet (LD) contacts, thanks to its CRAL-TRIO domain. MOSPD2 ensures the attachment of the ER to LDs through a direct protein-membrane interaction. The attachment mechanism involves an amphipathic helix that has an affinity for lipid packing defects present at the surface of LDs. Remarkably, the absence of MOSPD2 markedly disturbs the assembly of lipid droplets. These data show that MOSPD2, in addition to being a general ER receptor for inter-organelle contacts, possesses an additional tethering activity and is specifically implicated in the biology of LDs via its CRAL-TRIO domain.
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Affiliation(s)
- Mehdi Zouiouich
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
| | - Thomas Di Mattia
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
| | - Arthur Martinet
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
| | - Julie Eichler
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
| | - Corinne Wendling
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
| | - Nario Tomishige
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Erwan Grandgirard
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
| | - Nicolas Fuggetta
- Université Côte d’Azur, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
| | - Catherine Fromental-Ramain
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
| | - Giulia Mizzon
- European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, Heidelberg, Germany
| | - Calvin Dumesnil
- Laboratoire de Physique de l’École Normale Supérieure, Université Paris Sciences and Lettres, Centre National de la Recherche Scientifique, Sorbonne Université, Université de Paris, Paris, France
| | - Maxime Carpentier
- Laboratoire de Physique de l’École Normale Supérieure, Université Paris Sciences and Lettres, Centre National de la Recherche Scientifique, Sorbonne Université, Université de Paris, Paris, France
| | - Bernardo Reina-San-Martin
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
| | - Carole Mathelin
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
- Institut de Cancérologie Strasbourg Europe, Strasbourg, France
| | - Yannick Schwab
- European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, Heidelberg, Germany
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l’École Normale Supérieure, Université Paris Sciences and Lettres, Centre National de la Recherche Scientifique, Sorbonne Université, Université de Paris, Paris, France
| | - Toshihide Kobayashi
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Guillaume Drin
- Université Côte d’Azur, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
| | - Catherine Tomasetto
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
| | - Fabien Alpy
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
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6
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Molecular Dynamics Simulations Reveal Structural Interconnections within Sec14-PH Bipartite Domain from Human Neurofibromin. Int J Mol Sci 2022; 23:ijms23105707. [PMID: 35628517 PMCID: PMC9147397 DOI: 10.3390/ijms23105707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/18/2022] [Accepted: 05/19/2022] [Indexed: 12/10/2022] Open
Abstract
Neurofibromin, the main RasGAP in the nervous system, is a 2818 aa protein with several poorly characterized functional domains. Mutations in the NF1-encoding gene lead to an autosomal dominant syndrome, neurofibromatosis, with an incidence of 1 out of 3000 newborns. Missense mutations spread in the Sec14-PH-encoding sequences as well. Structural data could not highlight the defect in mutant Sec14-PH functionality. By performing molecular dynamics simulations at different temperatures, we found that the lid-lock is fundamental for the structural interdependence of the NF1 bipartite Sec14-PH domain. In fact, increased flexibility in the lid-lock loop, observed for the K1750Δ mutant, leads to disconnection of the two subdomains and can affect the stability of the Sec14 subdomain.
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7
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Gao YG, McDonald J, Malinina L, Patel DJ, Brown RE. Ceramide-1-phosphate transfer protein promotes sphingolipid reorientation needed for binding during membrane interaction. J Lipid Res 2022; 63:100151. [PMID: 34808193 PMCID: PMC8953657 DOI: 10.1016/j.jlr.2021.100151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 12/16/2022] Open
Abstract
Lipid transfer proteins acquire and release their lipid cargoes by interacting transiently with source and destination biomembranes. In the GlycoLipid Transfer Protein (GLTP) superfamily, the two-layer all-α-helical GLTP-fold defines proteins that specifically target sphingolipids (SLs) containing either sugar or phosphate headgroups via their conserved but evolutionarily-modified SL recognitions centers. Despite comprehensive structural insights provided by X-ray crystallography, the conformational dynamics associated with membrane interaction and SL uptake/release by GLTP superfamily members have remained unknown. Herein, we report insights gained from molecular dynamics (MD) simulations into the conformational dynamics that enable ceramide-1-phosphate transfer proteins (CPTPs) to acquire and deliver ceramide-1-phosphate (C1P) during interaction with 1-palmitoyl-2-oleoyl phosphatidylcholine bilayers. The focus on CPTP reflects this protein's involvement in regulating pro-inflammatory eicosanoid production and autophagy-dependent inflammasome assembly that drives interleukin (IL-1β and IL-18) production and release by surveillance cells. We found that membrane penetration by CPTP involved α-6 helix and the α-2 helix N-terminal region, was confined to one bilayer leaflet, and was relatively shallow. Large-scale dynamic conformational changes were minimal for CPTP during membrane interaction or C1P uptake except for the α-3/α-4 helices connecting loop, which is located near the membrane interface and interacts with certain phosphoinositide headgroups. Apart from functioning as a shallow membrane-docking element, α-6 helix was found to adeptly reorient membrane lipids to help guide C1P hydrocarbon chain insertion into the interior hydrophobic pocket of the SL binding site.These findings support a proposed 'hydrocarbon chain-first' mechanism for C1P uptake, in contrast to the 'lipid polar headgroup-first' uptake used by most lipid-transfer proteins.
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Affiliation(s)
- Yong-Guang Gao
- Hormel Institute, University of Minnesota, Austin, MN, USA.
| | | | - Lucy Malinina
- Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Dinshaw J Patel
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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8
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Emerging Prospects for Combating Fungal Infections by Targeting Phosphatidylinositol Transfer Proteins. Int J Mol Sci 2021; 22:ijms22136754. [PMID: 34201733 PMCID: PMC8269425 DOI: 10.3390/ijms22136754] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 06/11/2021] [Accepted: 06/11/2021] [Indexed: 12/27/2022] Open
Abstract
The emergence of fungal “superbugs” resistant to the limited cohort of anti-fungal agents available to clinicians is eroding our ability to effectively treat infections by these virulent pathogens. As the threat of fungal infection is escalating worldwide, this dwindling response capacity is fueling concerns of impending global health emergencies. These developments underscore the urgent need for new classes of anti-fungal drugs and, therefore, the identification of new targets. Phosphoinositide signaling does not immediately appear to offer attractive targets due to its evolutionary conservation across the Eukaryota. However, recent evidence argues otherwise. Herein, we discuss the evidence identifying Sec14-like phosphatidylinositol transfer proteins (PITPs) as unexplored portals through which phosphoinositide signaling in virulent fungi can be chemically disrupted with exquisite selectivity. Recent identification of lead compounds that target fungal Sec14 proteins, derived from several distinct chemical scaffolds, reveals exciting inroads into the rational design of next generation Sec14 inhibitors. Development of appropriately refined next generation Sec14-directed inhibitors promises to expand the chemical weaponry available for deployment in the shifting field of engagement between fungal pathogens and their human hosts.
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9
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Holič R, Šťastný D, Griač P. Sec14 family of lipid transfer proteins in yeasts. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158990. [PMID: 34118432 DOI: 10.1016/j.bbalip.2021.158990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 11/25/2022]
Abstract
The hydrophobicity of lipids prevents their free movement across the cytoplasm. To achieve highly heterogeneous and precisely regulated lipid distribution in different cellular membranes, lipids are transported by lipid transfer proteins (LTPs) in addition to their transport by vesicles. Sec14 family is one of the most extensively studied groups of LTPs. Here we provide an overview of Sec14 family of LTPs in the most studied yeast Saccharomyces cerevisiae as well as in other selected non-Saccharomyces yeasts-Schizosaccharomyces pombe, Kluyveromyces lactis, Candida albicans, Candida glabrata, Cryptococcus neoformans, and Yarrowia lipolytica. Discussed are specificities of Sec14-domain LTPs in various yeasts, their mode of action, subcellular localization, and physiological function. In addition, quite few Sec14 family LTPs are target of antifungal drugs, serve as modifiers of drug resistance or influence virulence of pathologic yeasts. Thus, they represent an important object of study from the perspective of human health.
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Affiliation(s)
- Roman Holič
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Dominik Šťastný
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Peter Griač
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovakia.
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10
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Khan D, Lee D, Gulten G, Aggarwal A, Wofford J, Krieger I, Tripathi A, Patrick JW, Eckert DM, Laganowsky A, Sacchettini J, Lindahl P, Bankaitis VA. A Sec14-like phosphatidylinositol transfer protein paralog defines a novel class of heme-binding proteins. eLife 2020; 9:57081. [PMID: 32780017 PMCID: PMC7462610 DOI: 10.7554/elife.57081] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 08/10/2020] [Indexed: 01/02/2023] Open
Abstract
Yeast Sfh5 is an unusual member of the Sec14-like phosphatidylinositol transfer protein (PITP) family. Whereas PITPs are defined by their abilities to transfer phosphatidylinositol between membranes in vitro, and to stimulate phosphoinositide signaling in vivo, Sfh5 does not exhibit these activities. Rather, Sfh5 is a redox-active penta-coordinate high spin FeIII hemoprotein with an unusual heme-binding arrangement that involves a co-axial tyrosine/histidine coordination strategy and a complex electronic structure connecting the open shell iron d-orbitals with three aromatic ring systems. That Sfh5 is not a PITP is supported by demonstrations that heme is not a readily exchangeable ligand, and that phosphatidylinositol-exchange activity is resuscitated in heme binding-deficient Sfh5 mutants. The collective data identify Sfh5 as the prototype of a new class of fungal hemoproteins, and emphasize the versatility of the Sec14-fold as scaffold for translating the binding of chemically distinct ligands to the control of diverse sets of cellular activities.
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Affiliation(s)
- Danish Khan
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, United States
| | - Dongju Lee
- Department of Molecular and Cellular Medicine, Texas A&M Health Sciences Center, College Station, United States
| | - Gulcin Gulten
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, United States
| | - Anup Aggarwal
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, United States
| | - Joshua Wofford
- Department of Chemistry, Texas A&M University, College Station, United States.,Department of Chemistry, Charleston Southern University, North Charleston, United States
| | - Inna Krieger
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, United States
| | - Ashutosh Tripathi
- Department of Molecular and Cellular Medicine, Texas A&M Health Sciences Center, College Station, United States
| | - John W Patrick
- Department of Chemistry, Texas A&M University, College Station, United States
| | - Debra M Eckert
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Arthur Laganowsky
- Department of Chemistry, Texas A&M University, College Station, United States
| | - James Sacchettini
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, United States
| | - Paul Lindahl
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, United States.,Department of Chemistry, Texas A&M University, College Station, United States
| | - Vytas A Bankaitis
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, United States.,Department of Molecular and Cellular Medicine, Texas A&M Health Sciences Center, College Station, United States.,Department of Chemistry, Texas A&M University, College Station, United States
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11
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Abstract
Lipids are distributed in a highly heterogeneous fashion in different cellular membranes. Only a minority of lipids achieve their final intracellular distribution through transport by vesicles. Instead, the bulk of lipid traffic is mediated by a large group of lipid transfer proteins (LTPs), which move small numbers of lipids at a time using hydrophobic cavities that stabilize lipid molecules outside membranes. Although the first LTPs were discovered almost 50 years ago, most progress in understanding these proteins has been made in the past few years, leading to considerable temporal and spatial refinement of our understanding of the function of these lipid transporters. The number of known LTPs has increased, with exciting discoveries of their multimeric assembly. Structural studies of LTPs have progressed from static crystal structures to dynamic structural approaches that show how conformational changes contribute to lipid handling at a sub-millisecond timescale. A major development has been the finding that many intracellular LTPs localize to two organelles at the same time, forming a shuttle, bridge or tube that links donor and acceptor compartments. The understanding of how different lipids achieve their final destination at the molecular level allows a better explanation of the range of defects that occur in diseases associated with lipid transport and distribution, opening up the possibility of developing therapies that specifically target lipid transfer.
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12
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Pemberton JG, Balla T. Polyphosphoinositide-Binding Domains: Insights from Peripheral Membrane and Lipid-Transfer Proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1111:77-137. [PMID: 30483964 DOI: 10.1007/5584_2018_288] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Within eukaryotic cells, biochemical reactions need to be organized on the surface of membrane compartments that use distinct lipid constituents to dynamically modulate the functions of integral proteins or influence the selective recruitment of peripheral membrane effectors. As a result of these complex interactions, a variety of human pathologies can be traced back to improper communication between proteins and membrane surfaces; either due to mutations that directly alter protein structure or as a result of changes in membrane lipid composition. Among the known structural lipids found in cellular membranes, phosphatidylinositol (PtdIns) is unique in that it also serves as the membrane-anchored precursor of low-abundance regulatory lipids, the polyphosphoinositides (PPIn), which have restricted distributions within specific subcellular compartments. The ability of PPIn lipids to function as signaling platforms relies on both non-specific electrostatic interactions and the selective stereospecific recognition of PPIn headgroups by specialized protein folds. In this chapter, we will attempt to summarize the structural diversity of modular PPIn-interacting domains that facilitate the reversible recruitment and conformational regulation of peripheral membrane proteins. Outside of protein folds capable of capturing PPIn headgroups at the membrane interface, recent studies detailing the selective binding and bilayer extraction of PPIn species by unique functional domains within specific families of lipid-transfer proteins will also be highlighted. Overall, this overview will help to outline the fundamental physiochemical mechanisms that facilitate localized interactions between PPIn lipids and the wide-variety of PPIn-binding proteins that are essential for the coordinate regulation of cellular metabolism and membrane dynamics.
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Affiliation(s)
- Joshua G Pemberton
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Tamas Balla
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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13
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Sugiura T, Takahashi C, Chuma Y, Fukuda M, Yamada M, Yoshida U, Nakao H, Ikeda K, Khan D, Nile AH, Bankaitis VA, Nakano M. Biophysical Parameters of the Sec14 Phospholipid Exchange Cycle. Biophys J 2018; 116:92-103. [PMID: 30580923 DOI: 10.1016/j.bpj.2018.11.3131] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 10/24/2018] [Accepted: 11/28/2018] [Indexed: 12/23/2022] Open
Abstract
Sec14, the major yeast phosphatidylcholine (PC)/phosphatidylinositol (PI) transfer protein (PITP), coordinates PC and PI metabolism to facilitate an appropriate and essential lipid signaling environment for membrane trafficking from trans-Golgi membranes. The Sec14 PI/PC exchange cycle is essential for its essential biological activity, but fundamental aspects of how this PITP executes its lipid transfer cycle remain unknown. To address some of these outstanding issues, we applied time-resolved small-angle neutron scattering for the determination of protein-mediated intervesicular movement of deuterated and hydrogenated phospholipids in vitro. Quantitative analysis by small-angle neutron scattering revealed that Sec14 PI- and PC-exchange activities were sensitive to both the lipid composition and curvature of membranes. Moreover, we report that these two parameters regulate lipid exchange activity via distinct mechanisms. Increased membrane curvature promoted both membrane binding and lipid exchange properties of Sec14, indicating that this PITP preferentially acts on the membrane site with a convexly curved face. This biophysical property likely constitutes part of a mechanism by which spatial specificity of Sec14 function is determined in cells. Finally, wild-type Sec14, but not a mixture of Sec14 proteins specifically deficient in either PC- or PI-binding activity, was able to effect a net transfer of PI or PC down opposing concentration gradients in vitro.
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Affiliation(s)
- Taichi Sugiura
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Chisato Takahashi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Yusuke Chuma
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Masakazu Fukuda
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Makiko Yamada
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Ukyo Yoshida
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Hiroyuki Nakao
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Keisuke Ikeda
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Danish Khan
- Departments of Biochemistry and Biophysics, Texas A&M University, College Station, Texas
| | - Aaron H Nile
- Department of Molecular & Cellular Medicine, Texas A&M Health Sciences Center, College Station, Texas
| | - Vytas A Bankaitis
- Departments of Biochemistry and Biophysics, Texas A&M University, College Station, Texas; Department of Molecular & Cellular Medicine, Texas A&M Health Sciences Center, College Station, Texas
| | - Minoru Nakano
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
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14
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Grabon A, Bankaitis VA, McDermott MI. The interface between phosphatidylinositol transfer protein function and phosphoinositide signaling in higher eukaryotes. J Lipid Res 2018; 60:242-268. [PMID: 30504233 DOI: 10.1194/jlr.r089730] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 11/12/2018] [Indexed: 12/22/2022] Open
Abstract
Phosphoinositides are key regulators of a large number of diverse cellular processes that include membrane trafficking, plasma membrane receptor signaling, cell proliferation, and transcription. How a small number of chemically distinct phosphoinositide signals are functionally amplified to exert specific control over such a diverse set of biological outcomes remains incompletely understood. To this end, a novel mechanism is now taking shape, and it involves phosphatidylinositol (PtdIns) transfer proteins (PITPs). The concept that PITPs exert instructive regulation of PtdIns 4-OH kinase activities and thereby channel phosphoinositide production to specific biological outcomes, identifies PITPs as central factors in the diversification of phosphoinositide signaling. There are two evolutionarily distinct families of PITPs: the Sec14-like and the StAR-related lipid transfer domain (START)-like families. Of these two families, the START-like PITPs are the least understood. Herein, we review recent insights into the biochemical, cellular, and physiological function of both PITP families with greater emphasis on the START-like PITPs, and we discuss the underlying mechanisms through which these proteins regulate phosphoinositide signaling and how these actions translate to human health and disease.
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Affiliation(s)
- Aby Grabon
- E. L. Wehner-Welch Laboratory, Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114
| | - Vytas A Bankaitis
- E. L. Wehner-Welch Laboratory, Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114
| | - Mark I McDermott
- E. L. Wehner-Welch Laboratory, Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114
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15
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Target Identification and Mechanism of Action of Picolinamide and Benzamide Chemotypes with Antifungal Properties. Cell Chem Biol 2018; 25:279-290.e7. [PMID: 29307839 DOI: 10.1016/j.chembiol.2017.12.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 10/18/2017] [Accepted: 12/06/2017] [Indexed: 11/20/2022]
Abstract
Invasive fungal infections are accompanied by high mortality rates that range up to 90%. At present, only three different compound classes are available for use in the clinic, and these often suffer from low bioavailability, toxicity, and drug resistance. These issues emphasize an urgent need for novel antifungal agents. Herein, we report the identification of chemically versatile benzamide and picolinamide scaffolds with antifungal properties. Chemogenomic profiling and biochemical assays with purified protein identified Sec14p, the major phosphatidylinositol/phosphatidylcholine transfer protein in Saccharomyces cerevisiae, as the sole essential target for these compounds. A functional variomics screen identified resistance-conferring residues that localized to the lipid-binding pocket of Sec14p. Determination of the X-ray co-crystal structure of a Sec14p-compound complex confirmed binding in this cavity and rationalized both the resistance-conferring residues and the observed structure-activity relationships. Taken together, these findings open new avenues for rational compound optimization and development of novel antifungal agents.
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16
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Grabon A, Orłowski A, Tripathi A, Vuorio J, Javanainen M, Róg T, Lönnfors M, McDermott MI, Siebert G, Somerharju P, Vattulainen I, Bankaitis VA. Dynamics and energetics of the mammalian phosphatidylinositol transfer protein phospholipid exchange cycle. J Biol Chem 2017; 292:14438-14455. [PMID: 28718450 DOI: 10.1074/jbc.m117.791467] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 07/14/2017] [Indexed: 11/06/2022] Open
Abstract
Phosphatidylinositol-transfer proteins (PITPs) regulate phosphoinositide signaling in eukaryotic cells. The defining feature of PITPs is their ability to exchange phosphatidylinositol (PtdIns) molecules between membranes, and this property is central to PITP-mediated regulation of lipid signaling. However, the details of the PITP-mediated lipid exchange cycle remain entirely obscure. Here, all-atom molecular dynamics simulations of the mammalian StART-like PtdIns/phosphatidylcholine (PtdCho) transfer protein PITPα, both on membrane bilayers and in solvated systems, informed downstream biochemical analyses that tested key aspects of the hypotheses generated by the molecular dynamics simulations. These studies provided five key insights into the PITPα lipid exchange cycle: (i) interaction of PITPα with the membrane is spontaneous and mediated by four specific protein substructures; (ii) the ability of PITPα to initiate closure around the PtdCho ligand is accompanied by loss of flexibility of two helix/loop regions, as well as of the C-terminal helix; (iii) the energy barrier of phospholipid extraction from the membrane is lowered by a network of hydrogen bonds between the lipid molecule and PITPα; (iv) the trajectory of PtdIns or PtdCho into and through the lipid-binding pocket is chaperoned by sets of PITPα residues conserved throughout the StART-like PITP family; and (v) conformational transitions in the C-terminal helix have specific functional involvements in PtdIns transfer activity. Taken together, these findings provide the first mechanistic description of key aspects of the PITPα PtdIns/PtdCho exchange cycle and offer a rationale for the high conservation of particular sets of residues across evolutionarily distant members of the metazoan StART-like PITP family.
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Affiliation(s)
- Aby Grabon
- From the Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, Texas 77843
| | - Adam Orłowski
- the Laboratory of Physics, Tampere University of Technology, FI-33720 Tampere, Finland.,the Department of Physics and Energy, University of Limerick, Limerick V94 T9PX, Ireland
| | - Ashutosh Tripathi
- From the Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, Texas 77843
| | - Joni Vuorio
- the Laboratory of Physics, Tampere University of Technology, FI-33720 Tampere, Finland.,the Department of Physics, University of Helsinki, P. O. Box 64, FI-00014 Helsinki, Finland
| | - Matti Javanainen
- the Laboratory of Physics, Tampere University of Technology, FI-33720 Tampere, Finland
| | - Tomasz Róg
- the Laboratory of Physics, Tampere University of Technology, FI-33720 Tampere, Finland.,the Department of Physics, University of Helsinki, P. O. Box 64, FI-00014 Helsinki, Finland
| | - Max Lönnfors
- From the Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, Texas 77843
| | - Mark I McDermott
- From the Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, Texas 77843
| | - Garland Siebert
- From the Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, Texas 77843
| | - Pentti Somerharju
- the Department of Biochemistry and Developmental Biology, University of Helsinki, P. O. Box 63, FI-00014 Helsinki, Finland
| | - Ilpo Vattulainen
- the Laboratory of Physics, Tampere University of Technology, FI-33720 Tampere, Finland, .,the Department of Physics, University of Helsinki, P. O. Box 64, FI-00014 Helsinki, Finland.,the Department of Physics and Chemistry, MEMPHYS, Center for Biomembrane Physics, University of Southern Denmark, DK-5230 Odense, Denmark, and
| | - Vytas A Bankaitis
- From the Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, Texas 77843, .,the Departments of Biochemistry and Biophysics and.,Chemistry, Texas A&M University, College Station, Texas 77843
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17
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Wong LH, Levine TP. Tubular lipid binding proteins (TULIPs) growing everywhere. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1439-1449. [PMID: 28554774 PMCID: PMC5507252 DOI: 10.1016/j.bbamcr.2017.05.019] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 05/11/2017] [Accepted: 05/17/2017] [Indexed: 12/27/2022]
Abstract
Tubular lipid binding proteins (TULIPs) have become a focus of interest in the cell biology of lipid signalling, lipid traffic and membrane contact sites. Each tubular domain has an internal pocket with a hydrophobic lining that can bind a hydrophobic molecule such as a lipid. This allows TULIP proteins to carry lipids through the aqueous phase. TULIP domains were first found in a large family of extracellular proteins related to the bacterial permeability-inducing protein (BPI) and cholesterol ester transfer protein (CETP). Since then, the same fold and lipid transfer capacity have been found in SMP domains (so-called for their occurrence in synaptotagmin, mitochondrial and lipid binding proteins), which localise to intracellular membrane contact sites. Here the methods for identifying known TULIPs are described, and used to find previously unreported TULIPs, one in the silk polymer and another in prokaryotes illustrated by the E. coli protein YceB. The bacterial TULIP alters views on the likely evolution of the domain, suggesting its presence in the last universal common ancestor. The major function of TULIPs is to handle lipids, but we still do not know how they work in detail, or how many more remain to be discovered. This article is part of a Special Issue entitled: Membrane Contact Sites edited by Christian Ungermann and Benoit Kornmann. Proteins with the tubular lipid binding fold exist in a wider variety than is usually appreciated. TULIPs are found in prokaryotes, altering views on their evolution. It is not yet known whether TULIPs transfer lipids as tunnels or as shuttles. Tests have not yet been done to say if TULIPs with SMP domains (for example E-syts and ERMES components) tether contact sites. It is likely that more TULIPs remain to be discovered.
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Affiliation(s)
- Louise H Wong
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Tim P Levine
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK.
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18
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Huang J, Ghosh R, Bankaitis VA. Sec14-like phosphatidylinositol transfer proteins and the biological landscape of phosphoinositide signaling in plants. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1352-1364. [PMID: 27038688 DOI: 10.1016/j.bbalip.2016.03.027] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/21/2016] [Accepted: 03/23/2016] [Indexed: 01/01/2023]
Abstract
Phosphoinositides and soluble inositol phosphates are essential components of a complex intracellular chemical code that regulates major aspects of lipid signaling in eukaryotes. These involvements span a broad array of biological outcomes and activities, and cells are faced with the problem of how to compartmentalize and organize these various signaling events into a coherent scheme. It is in the arena of how phosphoinositide signaling circuits are integrated and, and how phosphoinositide pools are functionally defined and channeled to privileged effectors, that phosphatidylinositol (PtdIns) transfer proteins (PITPs) are emerging as critical players. As plant systems offer some unique advantages and opportunities for study of these proteins, we discuss herein our perspectives regarding the progress made in plant systems regarding PITP function. We also suggest interesting prospects that plant systems hold for interrogating how PITPs work, particularly in multi-domain contexts, to diversify the biological outcomes for phosphoinositide signaling. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner.
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Affiliation(s)
- Jin Huang
- Department of Molecular & Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX 77843-1114 USA.
| | - Ratna Ghosh
- Department of Molecular & Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX 77843-1114 USA
| | - Vytas A Bankaitis
- Department of Molecular & Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX 77843-1114 USA; Department of Biochemistry & Biophysics, Texas A&M University, College Station, TX 77843-1114 USA; Department of Chemistry, Texas A&M University, College Station, TX 77843-1114 USA.
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19
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Hariri H, Ugrankar R, Liu Y, Henne WM. Inter-organelle ER-endolysosomal contact sites in metabolism and disease across evolution. Commun Integr Biol 2016; 9:e1156278. [PMID: 27489577 PMCID: PMC4951168 DOI: 10.1080/19420889.2016.1156278] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 02/13/2016] [Indexed: 12/29/2022] Open
Abstract
Since their initial observation, contact sites formed between different organelles have transitioned from ignored curiosities to recognized centers for the exchange of metabolites and lipids. Contact formed between the ER and endomembrane system (eg. the plasma membrane, endosomes, and lysosomes) is of particular biomedical interest, as it governs aspects of lipid metabolism, organelle identity, and cell signaling. Here, we review the field of ER-endolysosomal communication from the perspective of three model systems: budding yeast, the fruit fly D. melanogaster, and mammals. From this broad perspective, inter-organelle communication displays a consistent role in metabolic regulation that was differentially tuned during the development of complex metazoan life. We also examine the current state of understanding of lipid exchange between organelles, and discuss molecular mechanisms by which this occurs.
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Affiliation(s)
- Hanaa Hariri
- Department of Cell Biology, UT Southwestern Medical Center , Dallas, TX, USA
| | - Rupali Ugrankar
- Department of Cell Biology, UT Southwestern Medical Center , Dallas, TX, USA
| | - Yang Liu
- Department of Cell Biology, UT Southwestern Medical Center , Dallas, TX, USA
| | - W Mike Henne
- Department of Cell Biology, UT Southwestern Medical Center , Dallas, TX, USA
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20
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Sec14-like phosphatidylinositol-transfer proteins and diversification of phosphoinositide signalling outcomes. Biochem Soc Trans 2015; 42:1383-8. [PMID: 25233419 DOI: 10.1042/bst20140187] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The physiological functions of phosphatidylinositol (PtdIns)-transfer proteins (PITPs)/phosphatidylcholine (PtdCho)-transfer proteins are poorly characterized, even though these proteins are conserved throughout the eukaryotic kingdom. Much of the progress in elucidating PITP functions has come from exploitation of genetically tractable model organisms, but the mechanisms for how PITPs execute their biological activities remain unclear. Structural and molecular dynamics approaches are filling in the details for how these proteins actually work as molecules. In the present paper, we discuss our recent work with Sec14-like PITPs and describe how PITPs integrate diverse territories of the lipid metabolome with phosphoinositide signalling.
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21
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Structural insights on cholesterol endosynthesis: Binding of squalene and 2,3-oxidosqualene to supernatant protein factor. J Struct Biol 2015; 190:261-70. [DOI: 10.1016/j.jsb.2015.05.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 05/08/2015] [Accepted: 05/11/2015] [Indexed: 11/24/2022]
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22
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Grabon A, Khan D, Bankaitis VA. Phosphatidylinositol transfer proteins and instructive regulation of lipid kinase biology. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1851:724-35. [PMID: 25592381 PMCID: PMC5221696 DOI: 10.1016/j.bbalip.2014.12.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 11/21/2014] [Accepted: 12/16/2014] [Indexed: 11/25/2022]
Abstract
Phosphatidylinositol is a metabolic precursor of phosphoinositides and soluble inositol phosphates. Both sets of molecules represent versatile intracellular chemical signals in eukaryotes. While much effort has been invested in understanding the enzymes that produce and consume these molecules, central aspects for how phosphoinositide production is controlled and functionally partitioned remain unresolved and largely unappreciated. It is in this regard that phosphatidylinositol (PtdIns) transfer proteins (PITPs) are emerging as central regulators of the functional channeling of phosphoinositide pools produced on demand for specific signaling purposes. The physiological significance of these proteins is amply demonstrated by the consequences that accompany deficits in individual PITPs. Although the biological problem is fascinating, and of direct relevance to disease, PITPs remain largely uncharacterized. Herein, we discuss our perspectives regarding what is known about how PITPs work as molecules, and highlight progress in our understanding of how PITPs are integrated into cellular physiology. This article is part of a Special Issue entitled Phosphoinositides.
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Affiliation(s)
- Aby Grabon
- Department of Molecular & Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, USA
| | - Danish Khan
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, TX 77843-2128, USA
| | - Vytas A Bankaitis
- Department of Molecular & Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, USA; Department of Biochemistry & Biophysics, Texas A&M University, College Station, TX 77843-2128, USA.
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23
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Nile AH, Tripathi A, Yuan P, Mousley CJ, Suresh S, Wallace IM, Shah SD, Pohlhaus DT, Temple B, Nislow C, Giaever G, Tropsha A, Davis RW, St Onge RP, Bankaitis VA. PITPs as targets for selectively interfering with phosphoinositide signaling in cells. Nat Chem Biol 2014; 10:76-84. [PMID: 24292071 PMCID: PMC4059020 DOI: 10.1038/nchembio.1389] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 10/02/2013] [Indexed: 01/26/2023]
Abstract
Sec14-like phosphatidylinositol transfer proteins (PITPs) integrate diverse territories of intracellular lipid metabolism with stimulated phosphatidylinositol-4-phosphate production and are discriminating portals for interrogating phosphoinositide signaling. Yet, neither Sec14-like PITPs nor PITPs in general have been exploited as targets for chemical inhibition for such purposes. Herein, we validate what is to our knowledge the first small-molecule inhibitors (SMIs) of the yeast PITP Sec14. These SMIs are nitrophenyl(4-(2-methoxyphenyl)piperazin-1-yl)methanones (NPPMs) and are effective inhibitors in vitro and in vivo. We further establish that Sec14 is the sole essential NPPM target in yeast and that NPPMs exhibit exquisite targeting specificities for Sec14 (relative to related Sec14-like PITPs), propose a mechanism for how NPPMs exert their inhibitory effects and demonstrate that NPPMs exhibit exquisite pathway selectivity in inhibiting phosphoinositide signaling in cells. These data deliver proof of concept that PITP-directed SMIs offer new and generally applicable avenues for intervening with phosphoinositide signaling pathways with selectivities superior to those afforded by contemporary lipid kinase-directed strategies.
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Affiliation(s)
- Aaron H. Nile
- Department of Molecular & Cellular Medicine, Department of Biochemistry & Biophysics, Department of Chemistry, Texas A&M University, College Station, Texas 77843-1114 USA
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7090 USA
| | - Ashutosh Tripathi
- Department of Molecular & Cellular Medicine, Department of Biochemistry & Biophysics, Department of Chemistry, Texas A&M University, College Station, Texas 77843-1114 USA
- Laboratory for Molecular Modeling, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7355 USA
| | - Peihua Yuan
- Department of Molecular & Cellular Medicine, Department of Biochemistry & Biophysics, Department of Chemistry, Texas A&M University, College Station, Texas 77843-1114 USA
| | - Carl J. Mousley
- Department of Molecular & Cellular Medicine, Department of Biochemistry & Biophysics, Department of Chemistry, Texas A&M University, College Station, Texas 77843-1114 USA
| | - Sundari Suresh
- Department of Biochemistry, Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304
| | - Iain Michael Wallace
- Department of Biochemistry, Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304
| | - Sweety D. Shah
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7090 USA
| | - Denise Teotico Pohlhaus
- Laboratory for Molecular Modeling, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7355 USA
| | - Brenda Temple
- R. L. Juliano Structural Bioinformatics Core, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7260 USA
| | - Corey Nislow
- Faculty of Pharmaceutical Sciences,, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Guri Giaever
- Faculty of Pharmaceutical Sciences,, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Alexander Tropsha
- Laboratory for Molecular Modeling, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7355 USA
| | - Ronald W. Davis
- Department of Biochemistry, Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304
| | - Robert P. St Onge
- Department of Biochemistry, Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304
| | - Vytas A. Bankaitis
- Department of Molecular & Cellular Medicine, Department of Biochemistry & Biophysics, Department of Chemistry, Texas A&M University, College Station, Texas 77843-1114 USA
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7090 USA
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Bromley D, Anderson PC, Daggett V. Structural consequences of mutations to the α-tocopherol transfer protein associated with the neurodegenerative disease ataxia with vitamin E deficiency. Biochemistry 2013; 52:4264-73. [PMID: 23713716 DOI: 10.1021/bi4001084] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The α-tocopherol transfer protein (α-TTP) is a liver protein that transfers α-tocopherol (vitamin E) to very-low-density lipoproteins (VLDLs). These VLDLs are then circulated throughout the body to maintain blood α-tocopherol levels. Mutations to the α-TTP gene are associated with ataxia with vitamin E deficiency, a disease characterized by peripheral nerve degeneration. In this study, molecular dynamics simulations of the E141K and R59W disease-associated mutants were performed. The mutants displayed disruptions in and around the ligand-binding pocket. Structural analysis and ligand docking to the mutant structures predicted a decreased affinity for α-tocopherol. To determine the detailed mechanism of the mutation-related changes, we developed a new tool called ContactWalker that analyzes contact differences between mutant and wild-type proteins and highlights pathways of altered contacts within the mutant proteins. Taken together, our findings are in agreement with experiment and suggest structural explanations for the weakened ability of the mutants to bind and carry α-tocopherol.
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Affiliation(s)
- Dennis Bromley
- Division of Biomedical and Health Informatics, Department of Biomedical Informatics and Medical Education, University of Washington, Seattle, Washington 98195, USA
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25
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Yang H, Tong J, Leonard TA, Im YJ. Structural determinants for phosphatidylinositol recognition by Sfh3 and substrate-induced dimer-monomer transition during lipid transfer cycles. FEBS Lett 2013; 587:1610-6. [DOI: 10.1016/j.febslet.2013.04.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 03/13/2013] [Accepted: 04/05/2013] [Indexed: 10/26/2022]
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Yuan Y, Zhao W, Wang X, Gao Y, Niu L, Teng M. Dimeric Sfh3 has structural changes in its binding pocket that are associated with a dimer–monomer state transformation induced by substrate binding. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:313-23. [DOI: 10.1107/s0907444912046161] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 11/08/2012] [Indexed: 12/31/2022]
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Curwin AJ, LeBlanc MA, Fairn GD, McMaster CR. Localization of lipid raft proteins to the plasma membrane is a major function of the phospholipid transfer protein Sec14. PLoS One 2013; 8:e55388. [PMID: 23383173 PMCID: PMC3559501 DOI: 10.1371/journal.pone.0055388] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Accepted: 12/28/2012] [Indexed: 11/30/2022] Open
Abstract
The Sec14 protein domain is a conserved tertiary structure that binds hydrophobic ligands. The Sec14 protein from Saccharomyces cerevisiae is essential with studies of S. cerevisiae Sec14 cellular function facilitated by a sole temperature sensitive allele, sec14ts. The sec14ts allele encodes a protein with a point mutation resulting in a single amino acid change, Sec14G266D. In this study results from a genome-wide genetic screen, and pharmacological data, provide evidence that the Sec14G266D protein is present at a reduced level compared to wild type Sec14 due to its being targeted to the proteosome. Increased expression of the sec14ts allele ameliorated growth arrest, but did not restore the defects in membrane accumulation or vesicular transport known to be defective in sec14ts cells. We determined that trafficking and localization of two well characterized lipid raft resident proteins, Pma1 and Fus-Mid-GFP, were aberrant in sec14ts cells. Localization of both lipid raft proteins was restored upon increased expression of the sec14ts allele. We suggest that a major function provided by Sec14 is trafficking and localization of lipid raft proteins.
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Affiliation(s)
- Amy J. Curwin
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Marissa A. LeBlanc
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Gregory D. Fairn
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
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Winklbauer EM, de Campos MKF, Dynowski M, Schaaf G. A blueprint for functional engineering: Single point mutations reconstitute phosphatidylinositol presentation in a pseudo-Sec14 protein. Commun Integr Biol 2012; 4:674-8. [PMID: 22446525 DOI: 10.4161/cib.17064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Phosphoinositides, phosphorylated species of phosphatidylinositol (PtdIns), are critical regulatory lipids in all eukaryotic cells. The molecular mechanisms that lead to the phosphorylation of an individual PtdIns- or phosphoinositide molecule remain largely unkown even though lipid kinases and phosphatases involved in these processes have been studied in detail. The observation by us and others that liposomal PtdIns (and phosphoinositide) molecules are poor in vitro substrates for kinases and phosphatases raises the question of how these enzymes execute their function in living cells. Recent work indicates that Sec14, the founding member of a large superfamily of eukaryotic proteins, is crucial for the process of PtdIns phosphorylation. The collective data suggest that Sec14 mediates a heterotypic phospholipid exchange reaction of PtdIns with phosphatidylcholine (PtdCho) during which PtdIns becomes vulnerable for kinase attack and thereby promotes the generation of phosphoinositides.1,2 In a recent paper we address the molecular mechanism of this phospholipid (PL) exchange reaction in a pseudo-Sec14 protein (Sfh1) that we rendered functional by a directed evolution approach. We find that enhanced PL-cycling into and out of the hydrophobic pocket of these activated Sfh1 mutants depends on the reconfiguration of interactions between a C-terminal string motif and the floor of the hydrophobic pocket that results in increased oscillations in a helical gate that controls pocket access. Here we further discuss our findings and propose molecular dynamics simulations as a tool to approach energetically unfavorable transition states and to identify novel protein-ligand interactions invisible to X-ray crystallography.
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29
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Gupta AB, Wee LE, Zhou YT, Hortsch M, Low BC. Cross-species analyses identify the BNIP-2 and Cdc42GAP homology (BCH) domain as a distinct functional subclass of the CRAL_TRIO/Sec14 superfamily. PLoS One 2012; 7:e33863. [PMID: 22479462 PMCID: PMC3313917 DOI: 10.1371/journal.pone.0033863] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 02/18/2012] [Indexed: 11/19/2022] Open
Abstract
The CRAL_TRIO protein domain, which is unique to the Sec14 protein superfamily, binds to a diverse set of small lipophilic ligands. Similar domains are found in a range of different proteins including neurofibromatosis type-1, a Ras GTPase-activating Protein (RasGAP) and Rho guanine nucleotide exchange factors (RhoGEFs). Proteins containing this structural protein domain exhibit a low sequence similarity and ligand specificity while maintaining an overall characteristic three-dimensional structure. We have previously demonstrated that the BNIP-2 and Cdc42GAP Homology (BCH) protein domain, which shares a low sequence homology with the CRAL_TRIO domain, can serve as a regulatory scaffold that binds to Rho, RhoGEFs and RhoGAPs to control various cell signalling processes. In this work, we investigate 175 BCH domain-containing proteins from a wide range of different organisms. A phylogenetic analysis with ∼100 CRAL_TRIO and similar domains from eight representative species indicates a clear distinction of BCH-containing proteins as a novel subclass within the CRAL_TRIO/Sec14 superfamily. BCH-containing proteins contain a hallmark sequence motif R(R/K)h(R/K)(R/K)NL(R/K)xhhhhHPs (‘h’ is large and hydrophobic residue and ‘s’ is small and weekly polar residue) and can be further subdivided into three unique subtypes associated with BNIP-2-N, macro- and RhoGAP-type protein domains. A previously unknown group of genes encoding ‘BCH-only’ domains is also identified in plants and arthropod species. Based on an analysis of their gene-structure and their protein domain context we hypothesize that BCH domain-containing genes evolved through gene duplication, intron insertions and domain swapping events. Furthermore, we explore the point of divergence between BCH and CRAL-TRIO proteins in relation to their ability to bind small GTPases, GAPs and GEFs and lipid ligands. Our study suggests a need for a more extensive analysis of previously uncharacterized BCH, ‘BCH-like’ and CRAL_TRIO-containing proteins and their significance in regulating signaling events involving small GTPases.
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Affiliation(s)
- Anjali Bansal Gupta
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore
| | - Liang En Wee
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Yi Ting Zhou
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Michael Hortsch
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Boon Chuan Low
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore
- * E-mail:
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Bankaitis VA, Ile KE, Nile AH, Ren J, Ghosh R, Schaaf G. Thoughts on Sec14-like nanoreactors and phosphoinositide signaling. Adv Biol Regul 2012; 52:115-21. [PMID: 22776890 DOI: 10.1016/j.jbior.2011.11.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 11/11/2011] [Indexed: 10/28/2022]
Affiliation(s)
- Vytas A Bankaitis
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7090, USA.
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Devising Powerful Genetics, Biochemical and Structural Tools in the Functional Analysis of Phosphatidylinositol Transfer Proteins (PITPs) Across Diverse Species. Methods Cell Biol 2012; 108:249-302. [DOI: 10.1016/b978-0-12-386487-1.00013-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Mousley CJ, Davison JM, Bankaitis VA. Sec14 like PITPs couple lipid metabolism with phosphoinositide synthesis to regulate Golgi functionality. Subcell Biochem 2012; 59:271-87. [PMID: 22374094 DOI: 10.1007/978-94-007-3015-1_9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
An interface coordinating lipid metabolism with proteins that regulate membrane trafficking is necessary to regulate Golgi morphology and dynamics. Such an interface facilitates the membrane deformations required for vesicularization, forms platforms for protein recruitment and assembly on appropriate sites on a membrane surface and provides lipid co-factors for optimal protein activity in the proper spatio-temporally regulated manner. Importantly, Sec14 and Sec14-like proteins are a unique superfamily of proteins that sense specific aspects of lipid metabolism, employing this information to potentiate phosphoinositide production. Therefore, Sec14 and Sec14 like proteins form central conduits to integrate multiple aspects of lipid metabolism with productive phosphoinositide signaling.
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Affiliation(s)
- Carl J Mousley
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, 27599-7090, Chapel Hill, NC, USA,
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Ghosh R, Bankaitis VA. Phosphatidylinositol transfer proteins: negotiating the regulatory interface between lipid metabolism and lipid signaling in diverse cellular processes. Biofactors 2011; 37:290-308. [PMID: 21915936 DOI: 10.1002/biof.180] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Phosphoinositides represent only a small percentage of the total cellular lipid pool. Yet, these molecules play crucial roles in diverse intracellular processes such as signal transduction at membrane-cytosol interface, regulation of membrane trafficking, cytoskeleton organization, nuclear events, and the permeability and transport functions of the membrane. A central principle in such lipid-mediated signaling is the appropriate coordination of these events. Such an intricate coordination demands fine spatial and temporal control of lipid metabolism and organization, and consistent mechanisms for specifically coupling these parameters to dedicated physiological processes. In that regard, recent studies have identified Sec14-like phosphatidylcholine transfer protein (PITPs) as "coincidence detectors," which spatially and temporally link the diverse aspects of the cellular lipid metabolome with phosphoinositide signaling. The integral role of PITPs in eukaryotic signal transduction design is amply demonstrated by the mammalian diseases associated with the derangements in the function of these proteins, to stress response and developmental regulation in plants, to fungal dimorphism and pathogenicity, to membrane trafficking in yeast, and higher eukaryotes. This review updates the recent advances made in the understanding of how these proteins, specifically PITPs of the Sec14-protein superfamily, operate at the molecular level and further describes how this knowledge has advanced our perception on the diverse biological functions of PITPs.
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Affiliation(s)
- Ratna Ghosh
- Lineberger Comprehensive Cancer Center, Department of Cell and Developmental Biology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27526-7090, USA.
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34
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Jones JC, Temple BRS, Jones AM, Dohlman HG. Functional reconstitution of an atypical G protein heterotrimer and regulator of G protein signaling protein (RGS1) from Arabidopsis thaliana. J Biol Chem 2011; 286:13143-50. [PMID: 21325279 PMCID: PMC3075661 DOI: 10.1074/jbc.m110.190355] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 02/01/2011] [Indexed: 11/06/2022] Open
Abstract
It has long been known that animal heterotrimeric Gαβγ proteins are activated by cell-surface receptors that promote GTP binding to the Gα subunit and dissociation of the heterotrimer. In contrast, the Gα protein from Arabidopsis thaliana (AtGPA1) can activate itself without a receptor or other exchange factor. It is unknown how AtGPA1 is regulated by Gβγ and the RGS (regulator of G protein signaling) protein AtRGS1, which is comprised of an RGS domain fused to a receptor-like domain. To better understand the cycle of G protein activation and inactivation in plants, we purified and reconstituted AtGPA1, full-length AtRGS1, and two putative Gβγ dimers. We show that the Arabidopsis Gα protein binds to its cognate Gβγ dimer directly and in a nucleotide-dependent manner. Although animal Gβγ dimers inhibit GTP binding to the Gα subunit, AtGPA1 retains fast activation in the presence of its cognate Gβγ dimer. We show further that the full-length AtRGS1 protein accelerates GTP hydrolysis and thereby counteracts the fast nucleotide exchange rate of AtGPA1. Finally, we show that AtGPA1 is less stable in complex with GDP than in complex with GTP or the Gβγ dimer. Molecular dynamics simulations and biophysical studies reveal that altered stability is likely due to increased dynamic motion in the N-terminal α-helix and Switch II of AtGPA1. Thus, despite profound differences in the mechanisms of activation, the Arabidopsis G protein is readily inactivated by its cognate RGS protein and forms a stable, GDP-bound, heterotrimeric complex similar to that found in animals.
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Affiliation(s)
| | - Brenda R. S. Temple
- From the Department of Biochemistry and Biophysics
- R. L. Juliano Structural Bioinformatics Core Facility, and
| | - Alan M. Jones
- Departments of Pharmacology and
- Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Henrik G. Dohlman
- From the Department of Biochemistry and Biophysics
- Departments of Pharmacology and
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35
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Jones JC, Duffy JW, Machius M, Temple BRS, Dohlman HG, Jones AM. The crystal structure of a self-activating G protein alpha subunit reveals its distinct mechanism of signal initiation. Sci Signal 2011; 4:ra8. [PMID: 21304159 PMCID: PMC3551277 DOI: 10.1126/scisignal.2001446] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In animals, heterotrimeric guanine nucleotide-binding protein (G protein) signaling is initiated by G protein-coupled receptors (GPCRs), which activate G protein α subunits; however, the plant Arabidopsis thaliana lacks canonical GPCRs, and its G protein α subunit (AtGPA1) is self-activating. To investigate how AtGPA1 becomes activated, we determined its crystal structure. AtGPA1 is structurally similar to animal G protein α subunits, but our crystallographic and biophysical studies revealed that it had distinct properties. Notably, the helical domain of AtGPA1 displayed pronounced intrinsic disorder and a tendency to disengage from the Ras domain of the protein. Domain substitution experiments showed that the helical domain of AtGPA1 was necessary for self-activation and sufficient to confer self-activation to an animal G protein α subunit. These findings reveal the structural basis for a mechanism for G protein activation in Arabidopsis that is distinct from the well-established mechanism found in animals.
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Affiliation(s)
- Janice C. Jones
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jeffrey W. Duffy
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Mischa Machius
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA
- Center for Structural Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Brenda R. S. Temple
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA
- R. L. Juliano Structural Bio-informatics Core Facility, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Henrik G. Dohlman
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Alan M. Jones
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
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36
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Schaaf G, Dynowski M, Mousley CJ, Shah SD, Yuan P, Winklbauer EM, de Campos MKF, Trettin K, Quinones MC, Smirnova TI, Yanagisawa LL, Ortlund EA, Bankaitis VA. Resurrection of a functional phosphatidylinositol transfer protein from a pseudo-Sec14 scaffold by directed evolution. Mol Biol Cell 2011; 22:892-905. [PMID: 21248202 PMCID: PMC3057712 DOI: 10.1091/mbc.e10-11-0903] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Sec14-superfamily proteins integrate the lipid metabolome with phosphoinositide synthesis and signaling via primed presentation of phosphatidylinositol (PtdIns) to PtdIns kinases. Sec14 action as a PtdIns-presentation scaffold requires heterotypic exchange of phosphatidylcholine (PtdCho) for PtdIns, or vice versa, in a poorly understood progression of regulated conformational transitions. We identify mutations that confer Sec14-like activities to a functionally inert pseudo-Sec14 (Sfh1), which seemingly conserves all of the structural requirements for Sec14 function. Unexpectedly, the "activation" phenotype results from alteration of residues conserved between Sfh1 and Sec14. Using biochemical and biophysical, structural, and computational approaches, we find the activation mechanism reconfigures atomic interactions between amino acid side chains and internal water in an unusual hydrophilic microenvironment within the hydrophobic Sfh1 ligand-binding cavity. These altered dynamics reconstitute a functional "gating module" that propagates conformational energy from within the hydrophobic pocket to the helical unit that gates pocket access. The net effect is enhanced rates of phospholipid-cycling into and out of the Sfh1* hydrophobic pocket. Taken together, the directed evolution approach reveals an unexpectedly flexible functional engineering of a Sec14-like PtdIns transfer protein-an engineering invisible to standard bioinformatic, crystallographic, and rational mutagenesis approaches.
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Affiliation(s)
- Gabriel Schaaf
- Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA.
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37
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Nile AH, Bankaitis VA, Grabon A. Mammalian diseases of phosphatidylinositol transfer proteins and their homologs. CLINICAL LIPIDOLOGY 2010; 5:867-897. [PMID: 21603057 PMCID: PMC3097519 DOI: 10.2217/clp.10.67] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Inositol and phosphoinositide signaling pathways represent major regulatory systems in eukaryotes. The physiological importance of these pathways is amply demonstrated by the variety of diseases that involve derangements in individual steps in inositide and phosphoinositide production and degradation. These diseases include numerous cancers, lipodystrophies and neurological syndromes. Phosphatidylinositol transfer proteins (PITPs) are emerging as fascinating regulators of phosphoinositide metabolism. Recent advances identify PITPs (and PITP-like proteins) to be coincidence detectors, which spatially and temporally coordinate the activities of diverse aspects of the cellular lipid metabolome with phosphoinositide signaling. These insights are providing new ideas regarding mechanisms of inherited mammalian diseases associated with derangements in the activities of PITPs and PITP-like proteins.
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Affiliation(s)
- Aaron H Nile
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-27090, USA
| | - Vytas A Bankaitis
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-27090, USA
| | - Aby Grabon
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-27090, USA
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38
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Zhang WX, Thakur V, Lomize A, Pogozheva I, Panagabko C, Cecchini M, Baptist M, Morley S, Manor D, Atkinson J. The contribution of surface residues to membrane binding and ligand transfer by the α-tocopherol transfer protein (α-TTP). J Mol Biol 2010; 405:972-88. [PMID: 21110980 DOI: 10.1016/j.jmb.2010.11.028] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 11/13/2010] [Indexed: 12/20/2022]
Abstract
Previous work has shown that the α-tocopherol transfer protein (α-TTP) can bind to vesicular or immobilized phospholipid membranes. Revealing the molecular mechanisms by which α-TTP associates with membranes is thought to be critical to understanding its function and role in the secretion of tocopherol from hepatocytes into the circulation. Calculations presented in the Orientations of Proteins in Membranes database have provided a testable model for the spatial arrangement of α-TTP and other CRAL-TRIO family proteins with respect to the lipid bilayer. These calculations predicted that a hydrophobic surface mediates the interaction of α-TTP with lipid membranes. To test the validity of these predictions, we used site-directed mutagenesis and examined the substituted mutants with regard to intermembrane ligand transfer, association with lipid layers and biological activity in cultured hepatocytes. Substitution of residues in helices A8 (F165A and F169A) and A10 (I202A, V206A and M209A) decreased the rate of intermembrane ligand transfer as well as protein adsorption to phospholipid bilayers. The largest impairment was observed upon mutation of residues that are predicted to be fully immersed in the lipid bilayer in both apo (open) and holo (closed) conformations such as Phe165 and Phe169. Mutation F169A, and especially F169D, significantly impaired α-TTP-assisted secretion of α-tocopherol outside cultured hepatocytes. Mutation of selected basic residues (R192H, K211A, and K217A) had little effect on transfer rates, indicating no significant involvement of nonspecific electrostatic interactions with membranes.
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Affiliation(s)
- Wen Xiao Zhang
- Department of Chemistry, Brock University, St. Catharines, Ontario, Canada L2S3A1
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39
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Bankaitis VA, Mousley CJ, Schaaf G. The Sec14 superfamily and mechanisms for crosstalk between lipid metabolism and lipid signaling. Trends Biochem Sci 2009; 35:150-60. [PMID: 19926291 DOI: 10.1016/j.tibs.2009.10.008] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 10/26/2009] [Accepted: 10/27/2009] [Indexed: 01/03/2023]
Abstract
Lipid signaling pathways define central mechanisms for cellular regulation. Productive lipid signaling requires an orchestrated coupling between lipid metabolism, lipid organization and the action of protein machines that execute appropriate downstream reactions. Using membrane trafficking control as primary context, we explore the idea that the Sec14-protein superfamily defines a set of modules engineered for the sensing of specific aspects of lipid metabolism and subsequent transduction of 'sensing' information to a phosphoinositide-driven 'execution phase'. In this manner, the Sec14 superfamily connects diverse territories of the lipid metabolome with phosphoinositide signaling in a productive 'crosstalk' between these two systems. Mechanisms of crosstalk, by which non-enzymatic proteins integrate metabolic cues with the action of interfacial enzymes, represent unappreciated regulatory themes in lipid signaling.
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Affiliation(s)
- Vytas A Bankaitis
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill. Chapel Hill, North Carolina 27599-7090, USA
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40
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Bothnia dystrophy is caused by domino-like rearrangements in cellular retinaldehyde-binding protein mutant R234W. Proc Natl Acad Sci U S A 2009; 106:18545-50. [PMID: 19846785 DOI: 10.1073/pnas.0907454106] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cellular retinaldehyde-binding protein (CRALBP) is essential for mammalian vision by routing 11-cis-retinoids for the conversion of photobleached opsin molecules into photosensitive visual pigments. The arginine-to-tryptophan missense mutation in position 234 (R234W) in the human gene RLBP1 encoding CRALBP compromises visual pigment regeneration and is associated with Bothnia dystrophy. Here we report the crystal structures of both wild-type human CRALBP and of its mutant R234W as binary complexes complemented with the endogenous ligand 11-cis-retinal, at 3.0 and 1.7 A resolution, respectively. Our structural model of wild-type CRALBP locates R234 to a positively charged cleft at a distance of 15 A from the hydrophobic core sequestering 11-cis-retinal. The R234W structural model reveals burial of W234 and loss of dianion-binding interactions within the cleft with physiological implications for membrane docking. The burial of W234 is accompanied by a cascade of side-chain flips that effect the intrusion of the side-chain of I238 into the ligand-binding cavity. As consequence of the intrusion, R234W displays 5-fold increased resistance to light-induced photoisomerization relative to wild-type CRALBP, indicating tighter binding to 11-cis-retinal. Overall, our results reveal an unanticipated domino-like structural transition causing Bothnia-type retinal dystrophy by the impaired release of 11-cis-retinal from R234W.
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41
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Functional genomics of adhesion, invasion, and mycelial formation in Schizosaccharomyces pombe. EUKARYOTIC CELL 2009; 8:1298-306. [PMID: 19542312 DOI: 10.1128/ec.00078-09] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Investigation into the switch between single-celled and filamentous forms of fungi may provide insights into cell polarity, differentiation, and fungal pathogenicity. At the molecular level, much of this investigation has fallen on two closely related budding yeasts, Candida albicans and Saccharomyces cerevisiae. Recently, the much more distant fission yeast Schizosaccharomyces pombe was shown to form invasive filaments after nitrogen limitation (E. Amoah-Buahin, N. Bone, and J. Armstrong, Eukaryot. Cell 4:1287-1297, 2005) and this genetically tractable organism provides an alternative system for the study of dimorphic growth. Here we describe a second mode of mycelial formation of S. pombe, on rich media. Screening of an S. pombe haploid deletion library identified 12 genes required for mycelial development which encode potential transcription factors, orthologues of S. cerevisiae Sec14p and Tlg2p, and the formin For3, among others. These were further grouped into two phenotypic classes representing different stages of the process. We show that galactose-dependent cell adhesion and actin assembly are both required for mycelial formation and mutants lacking a range of genes controlling cell polarity all produce mycelia but with radically altered morphology.
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Mousley CJ, Tyeryar K, Ile KE, Schaaf G, Brost RL, Boone C, Guan X, Wenk MR, Bankaitis VA. Trans-Golgi network and endosome dynamics connect ceramide homeostasis with regulation of the unfolded protein response and TOR signaling in yeast. Mol Biol Cell 2008; 19:4785-803. [PMID: 18753406 DOI: 10.1091/mbc.e08-04-0426] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Synthetic genetic array analyses identify powerful genetic interactions between a thermosensitive allele (sec14-1(ts)) of the structural gene for the major yeast phosphatidylinositol transfer protein (SEC14) and a structural gene deletion allele (tlg2Delta) for the Tlg2 target membrane-soluble N-ethylmaleimide-sensitive factor attachment protein receptor. The data further demonstrate Sec14 is required for proper trans-Golgi network (TGN)/endosomal dynamics in yeast. Paradoxically, combinatorial depletion of Sec14 and Tlg2 activities elicits trafficking defects from the endoplasmic reticulum, and these defects are accompanied by compromise of the unfolded protein response (UPR). UPR failure occurs downstream of Hac1 mRNA splicing, and it is further accompanied by defects in TOR signaling. The data link TGN/endosomal dynamics with ceramide homeostasis, UPR activity, and TOR signaling in yeast, and they identify the Sit4 protein phosphatase as a primary conduit through which ceramides link to the UPR. We suggest combinatorial Sec14/Tlg2 dysfunction evokes inappropriate turnover of complex sphingolipids in endosomes. One result of this turnover is potentiation of ceramide-activated phosphatase-mediated down-regulation of the UPR. These results provide new insight into Sec14 function, and they emphasize the TGN/endosomal system as a central hub for homeostatic regulation in eukaryotes.
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Affiliation(s)
- Carl J Mousley
- Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7090, USA
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Curwin AJ, McMaster CR. Structure and function of the enigmatic Sec14 domain-containing proteins and the etiology of human disease. ACTA ACUST UNITED AC 2008. [DOI: 10.2217/17460875.3.4.399] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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D'Angelo G, Vicinanza M, De Matteis MA. Lipid-transfer proteins in biosynthetic pathways. Curr Opin Cell Biol 2008; 20:360-70. [PMID: 18490149 DOI: 10.1016/j.ceb.2008.03.013] [Citation(s) in RCA: 233] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 03/19/2008] [Accepted: 03/20/2008] [Indexed: 11/19/2022]
Abstract
Compartmentalization is a defining feature of eukaryotic cells that allows the spatial segregation of different functions, such as protein and lipid synthesis, and ensures their fidelity and efficiency. This imposes the need for an intense flux of metabolic intermediates between segregated enzymatic activities, as seen for the sequential transport of neosynthesized proteins through the segments of the secretory pathway during their post-translational modification. For lipid synthesis, the identification of proteins that transfer lipids between membranes has revealed an additional mechanism for this intercompartment exchange. The intense interest elicited by the lipid-transfer proteins over the last few years has led to the definition of their central role in key processes, such as lipid metabolism, membrane trafficking, and signaling.
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Affiliation(s)
- Giovanni D'Angelo
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro Chieti, Italy
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Schaaf G, Ortlund EA, Tyeryar KR, Mousley CJ, Ile KE, Garrett TA, Ren J, Woolls MJ, Raetz CR, Redinbo MR, Bankaitis VA. Functional anatomy of phospholipid binding and regulation of phosphoinositide homeostasis by proteins of the sec14 superfamily. Mol Cell 2008; 29:191-206. [PMID: 18243114 PMCID: PMC7808562 DOI: 10.1016/j.molcel.2007.11.026] [Citation(s) in RCA: 197] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2007] [Revised: 09/27/2007] [Accepted: 11/14/2007] [Indexed: 11/28/2022]
Abstract
Sec14, the major yeast phosphatidylinositol (PtdIns)/phosphatidylcholine (PtdCho) transfer protein, regulates essential interfaces between lipid metabolism and membrane trafficking from the trans-Golgi network (TGN). How Sec14 does so remains unclear. We report that Sec14 binds PtdIns and PtdCho at distinct (but overlapping) sites, and both PtdIns- and PtdCho-binding activities are essential Sec14 activities. We further show both activities must reside within the same molecule to reconstitute a functional Sec14 and for effective Sec14-mediated regulation of phosphoinositide homeostasis in vivo. This regulation is uncoupled from PtdIns-transfer activity and argues for an interfacial presentation mode for Sec14-mediated potentiation of PtdIns kinases. Such a regulatory role for Sec14 is a primary counter to action of the Kes1 sterol-binding protein that antagonizes PtdIns 4-OH kinase activity in vivo. Collectively, these findings outline functional mechanisms for the Sec14 superfamily and reveal additional layers of complexity for regulating phosphoinositide homeostasis in eukaryotes.
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Affiliation(s)
- Gabriel Schaaf
- Department of Cell and Developmental Biology, School of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA
- These authors contributed equally to this work
| | - Eric A. Ortlund
- Department of Chemistry, School of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA
- Department of Biochemistry and Biophysics, School of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA
- These authors contributed equally to this work
| | - Kimberly R. Tyeryar
- Department of Cell and Developmental Biology, School of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA
| | - Carl J. Mousley
- Department of Cell and Developmental Biology, School of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA
| | - Kristina E. Ile
- Department of Cell and Developmental Biology, School of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA
| | - Teresa A. Garrett
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Jihui Ren
- Department of Cell and Developmental Biology, School of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA
| | - Melissa J. Woolls
- Department of Cell and Developmental Biology, School of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA
| | - Christian R.H. Raetz
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Matthew R. Redinbo
- Department of Chemistry, School of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA
- Department of Biochemistry and Biophysics, School of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA
| | - Vytas A. Bankaitis
- Department of Cell and Developmental Biology, School of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA
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Current awareness on yeast. Yeast 2008. [DOI: 10.1002/yea.1455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Mousley CJ, Tyeryar KR, Vincent-Pope P, Bankaitis VA. The Sec14-superfamily and the regulatory interface between phospholipid metabolism and membrane trafficking. Biochim Biophys Acta Mol Cell Biol Lipids 2007; 1771:727-36. [PMID: 17512778 PMCID: PMC2001170 DOI: 10.1016/j.bbalip.2007.04.002] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Revised: 03/26/2007] [Accepted: 04/03/2007] [Indexed: 12/11/2022]
Abstract
A central principle of signal transduction is the appropriate control of the process so that relevant signals can be detected with fine spatial and temporal resolution. In the case of lipid-mediated signaling, organization and metabolism of specific lipid mediators is an important aspect of such control. Herein, we review the emerging evidence regarding the roles of Sec14-like phosphatidylinositol transfer proteins (PITPs) in the action of intracellular signaling networks; particularly as these relate to membrane trafficking. Finally, we explore developing ideas regarding how Sec14-like PITPs execute biological function. As Sec14-like proteins define a protein superfamily with diverse lipid (or lipophile) binding capabilities, it is likely these under-investigated proteins will be ultimately demonstrated as a ubiquitously important set of biological regulators whose functions influence a large territory in the signaling landscape of eukaryotic cells.
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Affiliation(s)
- Carl J Mousley
- Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA.
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