51
|
Campagnaro GD, de Koning HP. Purine and pyrimidine transporters of pathogenic protozoa - conduits for therapeutic agents. Med Res Rev 2020; 40:1679-1714. [PMID: 32144812 DOI: 10.1002/med.21667] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 02/12/2020] [Accepted: 02/18/2020] [Indexed: 02/06/2023]
Abstract
Purines and pyrimidines are essential nutrients for any cell. Most organisms are able to synthesize their own purines and pyrimidines, but this ability was lost in protozoans that adapted to parasitism, leading to a great diversification in transporter activities in these organisms, especially for the acquisition of amino acids and nucleosides from their hosts throughout their life cycles. Many of these transporters have been shown to have sufficiently different substrate affinities from mammalian transporters, making them good carriers for therapeutic agents. In this review, we summarize the knowledge obtained on purine and pyrimidine activities identified in protozoan parasites to date and discuss their importance for the survival of these parasites and as drug carriers, as well as the perspectives of developments in the field.
Collapse
Affiliation(s)
- Gustavo D Campagnaro
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, 120 University Place, Glasgow, UK
| | - Harry P de Koning
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, 120 University Place, Glasgow, UK
| |
Collapse
|
52
|
Wang C, Sun B, Zhang X, Huang X, Zhang M, Guo H, Chen X, Huang F, Chen T, Mi H, Yu F, Liu LN, Zhang P. Structural mechanism of the active bicarbonate transporter from cyanobacteria. NATURE PLANTS 2019; 5:1184-1193. [PMID: 31712753 DOI: 10.1038/s41477-019-0538-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Accepted: 09/27/2019] [Indexed: 05/11/2023]
Abstract
Bicarbonate transporters play essential roles in pH homeostasis in mammals and photosynthesis in aquatic photoautotrophs. A number of bicarbonate transporters have been characterized, among which is BicA-a low-affinity, high-flux SLC26-family bicarbonate transporter involved in cyanobacterial CO2-concentrating mechanisms (CCMs) that accumulate CO2 and improve photosynthetic carbon fixation. Here, we report the three-dimensional structure of BicA from Synechocystis sp. PCC6803. Crystal structures of the transmembrane domain (BicATM) and the cytoplasmic STAS domain (BicASTAS) of BicA were solved. BicATM was captured in an inward-facing HCO3--bound conformation and adopts a '7+7' fold monomer. HCO3- binds to a cytoplasm-facing hydrophilic pocket within the membrane. BicASTAS is assembled as a compact homodimer structure and is required for the dimerization of BicA. The dimeric structure of BicA was further analysed using cryo-electron microscopy and physiological analysis of the full-length BicA, and may represent the physiological unit of SLC26-family transporters. Comparing the BicATM structure with the outward-facing transmembrane domain structures of other bicarbonate transporters suggests an elevator transport mechanism that is applicable to the SLC26/4 family of sodium-dependent bicarbonate transporters. This study advances our knowledge of the structures and functions of cyanobacterial bicarbonate transporters, and will inform strategies for bioengineering functional BicA in heterologous organisms to increase assimilation of CO2.
Collapse
Affiliation(s)
- Chengcheng Wang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Bo Sun
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China
| | - Xue Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiaowei Huang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Minhua Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Hui Guo
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xin Chen
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Fang Huang
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Taiyu Chen
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Hualing Mi
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Fang Yu
- Shanghai Key Laboratory of Plant Molecualr Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Lu-Ning Liu
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Peng Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
| |
Collapse
|
53
|
Walter JD, Sawicka M, Dutzler R. Cryo-EM structures and functional characterization of murine Slc26a9 reveal mechanism of uncoupled chloride transport. eLife 2019; 8:46986. [PMID: 31339488 PMCID: PMC6656431 DOI: 10.7554/elife.46986] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 06/21/2019] [Indexed: 12/14/2022] Open
Abstract
The epithelial anion transporter SLC26A9 contributes to airway surface hydration and gastric acid production. Colocalizing with CFTR, SLC26A9 has been proposed as a target for the treatment of cystic fibrosis. To provide molecular details of its transport mechanism, we present cryo-EM structures and a functional characterization of murine Slc26a9. These structures define the general architecture of eukaryotic SLC26 family members and reveal an unusual mode of oligomerization which relies predominantly on the cytosolic STAS domain. Our data illustrates conformational transitions of Slc26a9, supporting a rapid alternate-access mechanism which mediates uncoupled chloride transport with negligible bicarbonate or sulfate permeability. The characterization of structure-guided mutants illuminates the properties of the ion transport path, including a selective anion binding site located in the center of a mobile module within the transmembrane domain. This study thus provides a structural foundation for the understanding of the entire SLC26 family and potentially facilitates their therapeutic exploitation. Many processes in the human body are regulated by chloride and other charged particles (known as ions) moving in and out of cells. Each cell is surrounded by a membrane barrier, which prevents ions from entering or exiting. Therefore, to control the levels of ions inside the cell, specific proteins in the membrane act as channels or transporters to provide routes for the ions to pass through the membrane. Channel proteins form pores that, when open, allow a steady stream of ions to pass through the membrane. Transporter proteins, on the other hand, generally contain a pocket that is only accessible from one side of the membrane. When individual ions enter this pocket the transporter changes shape. This causes the entrance of the pocket to close and then re-open on the other side of the membrane. Inside the lung, an ion channel known as CFTR provides a route for chloride ions to move out of cells, which helps clear harmful material from the airways. Mutations affecting this protein cause the mucus lining the airways to become very sticky, leading to a severe disease known as cystic fibrosis. CFTR works together with another protein that is also found in the membrane, called SLC26A9. Previous studies have suggested that SLC26A9 also allows chloride ions to pass through the membrane. It was not clear, however, if SLC26A9 operates as an ion channel or a transporter protein, or how the protein is arranged in the membrane. Now, Walter, Sawicka and Dutzler combined two techniques known as cryo-electron microscopy and patch-clamp electrophysiology to reveal the detailed three-dimensional structure of the mouse version of SLC26A9, which is highly similar to the human form. The experiments found that mouse SLC26A9 proteins form pairs in the membrane referred to as homodimers, which arranged themselves in an unexpected way. Further investigation into the structure of these homodimers suggests that despite having many channel-like properties, SLC26A9 operates as a fast transporter, rather than a true channel. These findings help us understand the role of SLC26A9 and other similar proteins in the lung and other parts of the body. In the future it may be possible to develop drugs that target SLC26A9 to treat cystic fibrosis and other severe lung diseases.
Collapse
Affiliation(s)
- Justin D Walter
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Marta Sawicka
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Raimund Dutzler
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| |
Collapse
|
54
|
Doukas A, Karena E, Botou M, Papakostas K, Papadaki A, Tziouvara O, Xingi E, Frillingos S, Boleti H. Heterologous expression of the mammalian sodium-nucleobase transporter rSNBT1 in Leishmania tarentolae. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:1546-1557. [PMID: 31283918 DOI: 10.1016/j.bbamem.2019.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 06/26/2019] [Accepted: 07/02/2019] [Indexed: 12/13/2022]
Abstract
Recombinant expression systems for mammalian membrane transport proteins are often limited by insufficient yields to support structural studies, inadequate post-translational processing and problems related with improper membrane targeting or cytotoxicity. Use of alternative expression systems and optimization of expression/purification protocols are constantly needed. In this work, we explore the applicability of the laboratory strain LEXSY of the ancient eukaryotic microorganism Leishmania tarentolae as a new expression system for mammalian nucleobase permeases of the NAT/NCS2 (Nucleobase-Ascorbate Transporter/Nucleobase-Cation Symporter-2) family. We achieved the heterologous expression of the purine-pyrimidine permease rSNBT1 from Rattus norvegicus (tagged at C-terminus with a red fluorescent protein), as confirmed by confocal microscopy and biochemical analysis of the subcellular fractions enriched in membrane proteins. The cDNA of rSNBT1 has been subcloned in a pLEXSY-sat-mrfp1vector and used to generate transgenic L. tarentolae-rsnbt1-mrfp1 strains carrying the pLEXSY-sat-rsnbt1-mrfp1 plasmid either episomally or integrated in the chromosomal DNA. The chimeric transporter rSNBT1-mRFP1 is targeted to the ER and the plasma membrane of the L. tarentolae promastigotes. The transgenic strains are capable of transporting nucleobases that are substrates of rSNBT1 but also of the endogenous L. tarentolae nucleoside/nucleobase transporters. A dipyridamole-resistant Na+-dependent fraction of uptake is attributed to the exogenously expressed rSNBT1.
Collapse
Affiliation(s)
- Anargyros Doukas
- Intracellular Parasitism Group, Microbiology Department, Hellenic Pasteur Institute, Vas. Sofias 127, Athens 11521, Greece
| | - Ekaterini Karena
- Laboratory of Biological Chemistry, Department of Medicine, University of Ioannina, Greece
| | - Maria Botou
- Laboratory of Biological Chemistry, Department of Medicine, University of Ioannina, Greece
| | | | - Amalia Papadaki
- Intracellular Parasitism Group, Microbiology Department, Hellenic Pasteur Institute, Vas. Sofias 127, Athens 11521, Greece
| | - Olympia Tziouvara
- Intracellular Parasitism Group, Microbiology Department, Hellenic Pasteur Institute, Vas. Sofias 127, Athens 11521, Greece
| | - Evaggelia Xingi
- Light Microscopy Unit, Hellenic Pasteur Institute, Vas. Sofias 127, Athens 11521, Greece
| | - Stathis Frillingos
- Laboratory of Biological Chemistry, Department of Medicine, University of Ioannina, Greece.
| | - Haralabia Boleti
- Intracellular Parasitism Group, Microbiology Department, Hellenic Pasteur Institute, Vas. Sofias 127, Athens 11521, Greece; Light Microscopy Unit, Hellenic Pasteur Institute, Vas. Sofias 127, Athens 11521, Greece.
| |
Collapse
|
55
|
Chang YN, Jaumann EA, Reichel K, Hartmann J, Oliver D, Hummer G, Joseph B, Geertsma ER. Structural basis for functional interactions in dimers of SLC26 transporters. Nat Commun 2019; 10:2032. [PMID: 31048734 PMCID: PMC6497670 DOI: 10.1038/s41467-019-10001-w] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 04/13/2019] [Indexed: 12/13/2022] Open
Abstract
The SLC26 family of transporters maintains anion equilibria in all kingdoms of life. The family shares a 7 + 7 transmembrane segments inverted repeat architecture with the SLC4 and SLC23 families, but holds a regulatory STAS domain in addition. While the only experimental SLC26 structure is monomeric, SLC26 proteins form structural and functional dimers in the lipid membrane. Here we resolve the structure of an SLC26 dimer embedded in a lipid membrane and characterize its functional relevance by combining PELDOR/DEER distance measurements and biochemical studies with MD simulations and spin-label ensemble refinement. Our structural model reveals a unique interface different from the SLC4 and SLC23 families. The functionally relevant STAS domain is no prerequisite for dimerization. Characterization of heterodimers indicates that protomers in the dimer functionally interact. The combined structural and functional data define the framework for a mechanistic understanding of functional cooperativity in SLC26 dimers.
Collapse
Affiliation(s)
- Yung-Ning Chang
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Eva A Jaumann
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Str. 7, 60438, Frankfurt am Main, Germany
| | - Katrin Reichel
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438, Frankfurt am Main, Germany
| | - Julia Hartmann
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University, 35037, Marburg, Germany
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University, 35037, Marburg, Germany.,DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, Philipps University, GRK 2213, Philipps, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438, Frankfurt am Main, Germany. .,Institute of Biophysics, Goethe University Frankfurt, Max-von-Laue Str. 1, 60438, Frankfurt am Main, Germany.
| | - Benesh Joseph
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Str. 7, 60438, Frankfurt am Main, Germany. .,Institute of Biophysics, Goethe University Frankfurt, Max-von-Laue Str. 1, 60438, Frankfurt am Main, Germany.
| | - Eric R Geertsma
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany.
| |
Collapse
|
56
|
Corradi V, Sejdiu BI, Mesa-Galloso H, Abdizadeh H, Noskov SY, Marrink SJ, Tieleman DP. Emerging Diversity in Lipid-Protein Interactions. Chem Rev 2019; 119:5775-5848. [PMID: 30758191 PMCID: PMC6509647 DOI: 10.1021/acs.chemrev.8b00451] [Citation(s) in RCA: 245] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
Membrane
lipids interact with proteins in a variety of ways, ranging
from providing a stable membrane environment for proteins to being
embedded in to detailed roles in complicated and well-regulated protein
functions. Experimental and computational advances are converging
in a rapidly expanding research area of lipid–protein interactions.
Experimentally, the database of high-resolution membrane protein structures
is growing, as are capabilities to identify the complex lipid composition
of different membranes, to probe the challenging time and length scales
of lipid–protein interactions, and to link lipid–protein
interactions to protein function in a variety of proteins. Computationally,
more accurate membrane models and more powerful computers now enable
a detailed look at lipid–protein interactions and increasing
overlap with experimental observations for validation and joint interpretation
of simulation and experiment. Here we review papers that use computational
approaches to study detailed lipid–protein interactions, together
with brief experimental and physiological contexts, aiming at comprehensive
coverage of simulation papers in the last five years. Overall, a complex
picture of lipid–protein interactions emerges, through a range
of mechanisms including modulation of the physical properties of the
lipid environment, detailed chemical interactions between lipids and
proteins, and key functional roles of very specific lipids binding
to well-defined binding sites on proteins. Computationally, despite
important limitations, molecular dynamics simulations with current
computer power and theoretical models are now in an excellent position
to answer detailed questions about lipid–protein interactions.
Collapse
Affiliation(s)
- Valentina Corradi
- Centre for Molecular Simulation and Department of Biological Sciences , University of Calgary , 2500 University Drive NW , Calgary , Alberta T2N 1N4 , Canada
| | - Besian I Sejdiu
- Centre for Molecular Simulation and Department of Biological Sciences , University of Calgary , 2500 University Drive NW , Calgary , Alberta T2N 1N4 , Canada
| | - Haydee Mesa-Galloso
- Centre for Molecular Simulation and Department of Biological Sciences , University of Calgary , 2500 University Drive NW , Calgary , Alberta T2N 1N4 , Canada
| | - Haleh Abdizadeh
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 7 , 9747 AG Groningen , The Netherlands
| | - Sergei Yu Noskov
- Centre for Molecular Simulation and Department of Biological Sciences , University of Calgary , 2500 University Drive NW , Calgary , Alberta T2N 1N4 , Canada
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 7 , 9747 AG Groningen , The Netherlands
| | - D Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences , University of Calgary , 2500 University Drive NW , Calgary , Alberta T2N 1N4 , Canada
| |
Collapse
|
57
|
Transporter oligomerisation: roles in structure and function. Biochem Soc Trans 2018; 47:433-440. [PMID: 30578344 PMCID: PMC6393857 DOI: 10.1042/bst20180316] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/18/2018] [Accepted: 11/15/2018] [Indexed: 01/27/2023]
Abstract
Oligomerisation is a key feature of integral membrane transporters with roles in structure, function and stability. In this review, we cover some very recent advances in our understanding of how oligomerisation affects these key transporter features, with emphasis on a few groups of transporters, including the nucleobase ascorbate transporters, neurotransmitter sodium symporters and major facilitator superfamily members.
Collapse
|
58
|
Hrmova M, Gilliham M. Plants fighting back: to transport or not to transport, this is a structural question. CURRENT OPINION IN PLANT BIOLOGY 2018; 46:68-76. [PMID: 30138844 DOI: 10.1016/j.pbi.2018.07.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 07/06/2018] [Accepted: 07/12/2018] [Indexed: 06/08/2023]
Abstract
Membrane-embedded transport proteins are fundamental to life; their co-ordinated action controls the movement and distribution of solutes into, around and out of cells for signalling, metabolism, nutrition, stress tolerance and development. Here we outline two case studies of transport systems that plants use to tolerate soil elemental toxicity, demonstrating how iterative studies of protein structure and function result in unparalleled insights into transport mechanics. Further, we propose that integrative platforms of biological, biochemical and biophysical tools can provide quantitative data on substrate specificity and transport rates, which are important in understanding transporter evolution and their roles in cell biology and whole plant physiology. Such knowledge equips biotechnologists and breeders with the power to deliver improvements in crop yields in sub-optimal soils.
Collapse
Affiliation(s)
- Maria Hrmova
- School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia; School of Life Sciences, Huaiyin Normal University, Huai'an 223300, China.
| | - Matthew Gilliham
- School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia; Australian Research Council Centre of Excellence in Plant Energy Biology, University of Adelaide, Waite Research Institute, Glen Osmond, South Australia 5064, Australia
| |
Collapse
|
59
|
Chaliotis A, Vlastaridis P, Ntountoumi C, Botou M, Yalelis V, Lazou P, Tatsaki E, Mossialos D, Frillingos S, Amoutzias GD. NAT/NCS2-hound: a webserver for the detection and evolutionary classification of prokaryotic and eukaryotic nucleobase-cation symporters of the NAT/NCS2 family. Gigascience 2018; 7:5168872. [PMID: 30418564 PMCID: PMC6308229 DOI: 10.1093/gigascience/giy133] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 10/17/2018] [Indexed: 01/16/2023] Open
Abstract
Nucleobase transporters are important for supplying the cell with purines and/or pyrimidines, for controlling the intracellular pool of nucleotides, and for obtaining exogenous nitrogen/carbon sources for metabolism. Nucleobase transporters are also evaluated as potential targets for antimicrobial therapies, since several pathogenic microorganisms rely on purine/pyrimidine salvage from their hosts. The majority of known nucleobase transporters belong to the evolutionarily conserved and ubiquitous nucleobase-ascorbate transporter/nucleobase-cation symporter-2 (NAT/NCS2) protein family. Based on a large-scale phylogenetic analysis that we performed on thousands of prokaryotic proteomes, we developed a webserver that can detect and distinguish this family of transporters from other homologous families that recognize different substrates. We can further categorize these transporters to certain evolutionary groups with distinct substrate preferences. The webserver scans whole proteomes and graphically displays which proteins are identified as NAT/NCS2, to which evolutionary groups and subgroups they belong to, and which conserved motifs they have. For key subgroups and motifs, the server displays annotated information from published crystal-structures and mutational studies pointing to key functional amino acids that may help experts assess the transport capability of the target sequences. The server is 100% accurate in detecting NAT/NCS2 family members. We also used the server to analyze 9,109 prokaryotic proteomes and identified Clostridia, Bacilli, β- and γ-Proteobacteria, Actinobacteria, and Fusobacteria as the taxa with the largest number of NAT/NCS2 transporters per proteome. An analysis of 120 representative eukaryotic proteomes also demonstrates the server's capability of correctly analyzing this major lineage, with plants emerging as the group with the highest number of NAT/NCS2 members per proteome.
Collapse
Affiliation(s)
- A Chaliotis
- Bioinformatics Laboratory, Department of Biochemistry and Biotechnology, University of Thessaly, Larisa, 41500, Greece
| | - P Vlastaridis
- Bioinformatics Laboratory, Department of Biochemistry and Biotechnology, University of Thessaly, Larisa, 41500, Greece
| | - C Ntountoumi
- Bioinformatics Laboratory, Department of Biochemistry and Biotechnology, University of Thessaly, Larisa, 41500, Greece
| | - M Botou
- Laboratory of Biological Chemistry, Department of Medicine, University of Ioannina, Ioannina, 45110, Greece
| | - V Yalelis
- Laboratory of Biological Chemistry, Department of Medicine, University of Ioannina, Ioannina, 45110, Greece
| | - P Lazou
- Laboratory of Biological Chemistry, Department of Medicine, University of Ioannina, Ioannina, 45110, Greece
| | - E Tatsaki
- Laboratory of Biological Chemistry, Department of Medicine, University of Ioannina, Ioannina, 45110, Greece
| | - D Mossialos
- Molecular Bacteriology Laboratory, Department of Biochemistry and Biotechnology, University of Thessaly, Larisa, 41500, Greece
| | - S Frillingos
- Laboratory of Biological Chemistry, Department of Medicine, University of Ioannina, Ioannina, 45110, Greece
| | - G D Amoutzias
- Bioinformatics Laboratory, Department of Biochemistry and Biotechnology, University of Thessaly, Larisa, 41500, Greece
| |
Collapse
|
60
|
Rapp CL, Li J, Badior KE, Williams DB, Casey JR, Reithmeier RAF. Role of N-glycosylation in the expression of human SLC26A2 and A3 anion transport membrane glycoproteins 1. Biochem Cell Biol 2018; 97:290-306. [PMID: 30462520 DOI: 10.1139/bcb-2018-0139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The human solute carrier 26 (SLC26) gene family of anion transporters consists of 10 members (SLC26A1-A11, A10 being a pseudogene) that encode membrane glycoproteins with 14 transmembrane segments and a C-terminal cytoplasmic sulfate transporter anti-sigma antagonist domain. Thus far, mutations in eight members of the SLC26 family (A1-A6, A8, and A9) have been linked to diseases in humans. Our goal is to characterize the role of N-glycosylation and the effect of mutations in SLC26A2 and A3 proteins on their functional expression in transfected HEK-293 cells. We found that certain mutants were retained in the endoplamic reticulum via an interaction with the lectin chaperone calnexin. Some could escape protein quality control and traffic to the cell surface upon removal of the N-glycosylation sites. Furthermore, we found that loss of N-glycosylation reduced expression of SLC26A2 at the cell surface. Loss of N-glycosylation had no effect on the stability of SLC26A3, yet resulted in a profound decrease in transport activity. Thus, N-glycosylation plays three roles in the functional expression of SLC26 proteins: (1) to retain misfolded proteins in the endoplamic reticulum, (2) to stabilize the protein at the cell surface, and (3) to maintain the transport protein in a functional state.
Collapse
Affiliation(s)
- Chloe L Rapp
- a Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Jing Li
- a Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Katherine E Badior
- b Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - David B Williams
- a Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Joseph R Casey
- b Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | | |
Collapse
|
61
|
Stoffer-Bittner AJ, Alexander CR, Dingman DW, Mourad GS, Schultes NP. Functional characterization of the uracil transporter from honeybee pathogen Paenibacillus larvae. Microb Pathog 2018; 124:305-310. [DOI: 10.1016/j.micpath.2018.08.059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 08/25/2018] [Indexed: 11/30/2022]
|
62
|
Yang L, Yang L, Yu H, Liu L, Zhao X, Huang X. Conformational transitions of uracil transporter UraA from Escherichia coli: a molecular simulation study. J Biomol Struct Dyn 2018; 36:3398-3410. [DOI: 10.1080/07391102.2017.1388288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Liu Yang
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130012, People’s Republic of China
| | - Lianjuan Yang
- The Fungal Reference Laboratory of Shanghai Dermatology Hospital, Shanghai 200050, China
| | - Hui Yu
- Chemistry Teaching Center, College of Chemistry and Biology, Beihai University, Jilin 132013, People’s Republic of China
| | - Lu Liu
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130012, People’s Republic of China
| | - Xi Zhao
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130012, People’s Republic of China
| | - Xuri Huang
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130012, People’s Republic of China
| |
Collapse
|
63
|
Gavriil ES, Dimitrakis S, Papadaki G, Balaska S, Lambrinidis G, Lougiakis N, Marakos P, Diallinas G, Pouli N, Mikros E. Structure-activity relationships in fungal nucleobases transporters as dissected by the inhibitory effects of novel purine analogues. Eur J Med Chem 2018; 156:240-251. [DOI: 10.1016/j.ejmech.2018.06.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 06/13/2018] [Accepted: 06/13/2018] [Indexed: 01/21/2023]
|
64
|
Stoffer‐Bittner AJ, Alexander CR, Dingman DW, Mourad GS, Schultes NP. The solute transport and binding profile of a novel nucleobase cation symporter 2 from the honeybee pathogen Paenibacillus larvae. FEBS Open Bio 2018; 8:1322-1331. [PMID: 30087835 PMCID: PMC6070649 DOI: 10.1002/2211-5463.12488] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 06/22/2018] [Accepted: 06/24/2018] [Indexed: 11/29/2022] Open
Abstract
Here, we report that a novel nucleobase cation symporter 2 encoded in the genome of the honeybee bacterial pathogen Paenibacillus larvae reveals high levels of amino acid sequence similarity to the Escherichia coli and Bacillus subtilis uric acid and xanthine transporters. This transporter is named P. larvae uric acid permease-like protein (PlUacP). Even though PlUacP displays overall amino acid sequence similarities, has common secondary structures, and shares functional motifs and functionally important amino acids with E. coli xanthine and uric acid transporters, these commonalities are insufficient to assign transport function to PlUacP. The solute transport and binding profile of PlUacP was determined by radiolabeled uptake experiments via heterologous expression in nucleobase transporter-deficient Saccharomyces cerevisiae strains. PlUacP transports the purines adenine and guanine and the pyrimidine uracil. Hypoxanthine, xanthine, and cytosine are not transported by PlUacP, but, along with uric acid, bind in a competitive manner. PlUacP has strong affinity for adenine Km 7.04 ± 0.18 μm, and as with other bacterial and plant NCS2 proteins, PlUacP function is inhibited by the proton disruptor carbonyl cyanide m-chlorophenylhydrazone. The solute transport and binding profile identifies PlUacP as a novel nucleobase transporter.
Collapse
Affiliation(s)
| | | | - Douglas W. Dingman
- Department of EntomologyThe Connecticut Agricultural Experiment StationNew HavenCTUSA
| | - George S. Mourad
- Department of BiologyIndiana University‐Purdue University Fort WayneINUSA
| | - Neil P. Schultes
- Department of Plant Pathology & EcologyThe Connecticut Agricultural Experiment StationNew HavenCTUSA
| |
Collapse
|
65
|
Kalli AC, Reithmeier RAF. Interaction of the human erythrocyte Band 3 anion exchanger 1 (AE1, SLC4A1) with lipids and glycophorin A: Molecular organization of the Wright (Wr) blood group antigen. PLoS Comput Biol 2018; 14:e1006284. [PMID: 30011272 PMCID: PMC6080803 DOI: 10.1371/journal.pcbi.1006284] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 08/07/2018] [Accepted: 06/08/2018] [Indexed: 11/29/2022] Open
Abstract
The Band 3 (AE1, SLC4A1) membrane protein is found in red blood cells and in kidney where it functions as an electro-neutral chloride/bicarbonate exchanger. In this study, we have used molecular dynamics simulations to provide the first realistic model of the dimeric membrane domain of human Band 3 in an asymmetric lipid bilayer containing a full complement of phospholipids, including phosphatidylinositol 4,5–bisphosphate (PIP2) and cholesterol, and its partner membrane protein Glycophorin A (GPA). The simulations show that the annular layer in the inner leaflet surrounding Band 3 was enriched in phosphatidylserine and PIP2 molecules. Cholesterol was also enriched around Band 3 but also at the dimer interface. The interaction of these lipids with specific sites on Band 3 may play a role in the folding and function of this anion transport membrane protein. GPA associates with Band 3 to form the Wright (Wr) blood group antigen, an interaction that involves an ionic bond between Glu658 in Band 3 and Arg61 in GPA. We were able to recreate this complex by performing simulations to allow the dimeric transmembrane portion of GPA to interact with Band 3 in a model membrane. Large-scale simulations showed that the GPA dimer can bridge Band 3 dimers resulting in the dynamic formation of long strands of alternating Band 3 and GPA dimers. Human Band 3 (AE1, SLC4A1), an abundant 911 amino acid glycoprotein, catalyzes the exchange of bicarbonate and chloride across the red blood cell membrane, a process necessary for efficient respiration. Malfunction of Band 3 leads to inherited diseases such as Southeast Asian Ovalocytosis, hereditary spherocytosis and distal renal tubular acidosis. Despite much available structural and functional data about Band 3, key questions about the conformational changes associated with transport and the molecular details of its interaction with lipids and other proteins remain unanswered. In this study, we have used computer simulations to investigate the dynamics of Band 3 in lipid bilayers that resemble the red blood cell plasma membrane. Our results suggest that negatively charged phospholipids and cholesterol interact strongly with Band 3 forming an annulus around the protein. Glycophorin A (GPA) interacts with Band 3 to form the Wright (Wr) blood group antigen. We were able to recreate this complex and show that GPA promotes the clustering of Band 3 in red blood cell membranes. Understanding the molecular details of the interaction of Band 3 with GPA has provided new insights into the nature of the Wright blood group antigen.
Collapse
Affiliation(s)
- Antreas C. Kalli
- Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
- * E-mail:
| | | |
Collapse
|
66
|
Chai W, Peng X, Liu B, Wang J, Zhu Z, Liu Y, Zhao K, Cheng B, Si W, Jiang H. Comparative Genomics, Whole-Genome Re-sequencing and Expression Profile Analysis of Nucleobase:Cation Symporter 2 ( NCS2) Genes in Maize. FRONTIERS IN PLANT SCIENCE 2018; 9:856. [PMID: 30002663 PMCID: PMC6031955 DOI: 10.3389/fpls.2018.00856] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 06/01/2018] [Indexed: 06/08/2023]
Abstract
Nucleobase:cation symporter 2 (NCS2) proteins are important for the transport of free nucleobases, participating in diverse plant growth and developmental processes, as well as response to abiotic stress. To date, a comprehensive analysis of the NCS2 gene family has not been performed in maize. In this study, we conducted a comparative genomics analysis of NCS2 genes in 28 plant species, ranging from aquatic algae to land plants, concentrating mainly on maize. Gene duplication events contributed to the expansion of NCS2 genes from lower aquatic plants to higher angiosperms, and whole-genome/segmental and single-gene duplication events were responsible for the expansion of the maize NCS2 gene family. Phylogenetic construction showed three NCS2 subfamilies, I, II, and III. According to homology-based relationships, members of subfamily I are NCS2/AzgA-like genes, whereas those in subfamilies II and III are NCS2/NATs. Moreover, subfamily I exhibited ancient origins. A motif compositional analysis showed that one symbolic motif (motif 4) of the NCS2/NAT genes was absent in subfamily I. In maize, three NCS2/AzgA-like and 21 NCS2/NAT genes were identified, and purifying selection influenced the duplication of maize NCS2 genes. Additionally, a population genetic analysis of NCS2 genes revealed that ZmNCS2-21 showed the greatest diversity between the 78 inbred and 22 wild surveyed maize populations. An expression profile analysis using transcriptome data and quantitative real-time PCR revealed that NCS2 genes in maize are involved in diverse developmental processes and responses to abiotic stresses, including abscisic acid, salt (NaCl), polyethylene glycol, and low (4°C) and high (42°C) temperatures. ZmNCS2 genes with relatively close relationships had similar expression patterns, strongly indicating functional redundancy. Finally, ZmNCS2-16 and ZmNCS2-23 localize in the plasma membrane, which confirmed their predicted membrane structures. These results provide a foundation for future studies regarding the functions of ZmNCS2 proteins, particularly those with potentially important roles in plant responses to abiotic stresses.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | - Weina Si
- National Engineering Laboratory of Crop Stress Resistance Breeding, School of Life Sciences, Anhui Agricultural University, Hefei, China
| | - Haiyang Jiang
- National Engineering Laboratory of Crop Stress Resistance Breeding, School of Life Sciences, Anhui Agricultural University, Hefei, China
| |
Collapse
|
67
|
Abbas YM, Toye AM, Rubinstein JL, Reithmeier RA. Band 3 function and dysfunction in a structural context. Curr Opin Hematol 2018; 25:163-170. [DOI: 10.1097/moh.0000000000000418] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
68
|
Bai X, Moraes TF, Reithmeier RAF. Structural biology of solute carrier (SLC) membrane transport proteins. Mol Membr Biol 2018; 34:1-32. [PMID: 29651895 DOI: 10.1080/09687688.2018.1448123] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The human solute carriers (SLCs) comprise over 400 different transporters, organized into 65 families ( http://slc.bioparadigms.org/ ) based on their sequence homology and transport function. SLCs are responsible for transporting extraordinarily diverse solutes across biological membranes, including inorganic ions, amino acids, lipids, sugars, neurotransmitters and drugs. Most of these membrane proteins function as coupled symporters (co-transporters) utilizing downhill ion (H+ or Na+) gradients as the driving force for the transport of substrate against its concentration gradient into cells. Other members work as antiporters (exchangers) that typically contain a single substrate-binding site with an alternating access mode of transport, while a few members exhibit channel-like properties. Dysfunction of SLCs is correlated with numerous human diseases and therefore they are potential therapeutic drug targets. In this review, we identified all of the SLC crystal structures that have been determined, most of which are from prokaryotic species. We further sorted all the SLC structures into four main groups with different protein folds and further discuss the well-characterized MFS (major facilitator superfamily) and LeuT (leucine transporter) folds. This review provides a systematic analysis of the structure, molecular basis of substrate recognition and mechanism of action in different SLC family members.
Collapse
Affiliation(s)
- Xiaoyun Bai
- a Department of Biochemistry , University of Toronto , Toronto , Canada
| | - Trevor F Moraes
- a Department of Biochemistry , University of Toronto , Toronto , Canada
| | | |
Collapse
|
69
|
Chipot C, Dehez F, Schnell JR, Zitzmann N, Pebay-Peyroula E, Catoire LJ, Miroux B, Kunji ERS, Veglia G, Cross TA, Schanda P. Perturbations of Native Membrane Protein Structure in Alkyl Phosphocholine Detergents: A Critical Assessment of NMR and Biophysical Studies. Chem Rev 2018; 118:3559-3607. [PMID: 29488756 PMCID: PMC5896743 DOI: 10.1021/acs.chemrev.7b00570] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Indexed: 12/25/2022]
Abstract
Membrane proteins perform a host of vital cellular functions. Deciphering the molecular mechanisms whereby they fulfill these functions requires detailed biophysical and structural investigations. Detergents have proven pivotal to extract the protein from its native surroundings. Yet, they provide a milieu that departs significantly from that of the biological membrane, to the extent that the structure, the dynamics, and the interactions of membrane proteins in detergents may considerably vary, as compared to the native environment. Understanding the impact of detergents on membrane proteins is, therefore, crucial to assess the biological relevance of results obtained in detergents. Here, we review the strengths and weaknesses of alkyl phosphocholines (or foscholines), the most widely used detergent in solution-NMR studies of membrane proteins. While this class of detergents is often successful for membrane protein solubilization, a growing list of examples points to destabilizing and denaturing properties, in particular for α-helical membrane proteins. Our comprehensive analysis stresses the importance of stringent controls when working with this class of detergents and when analyzing the structure and dynamics of membrane proteins in alkyl phosphocholine detergents.
Collapse
Affiliation(s)
- Christophe Chipot
- SRSMC, UMR 7019 Université de Lorraine CNRS, Vandoeuvre-les-Nancy F-54500, France
- Laboratoire
International Associé CNRS and University of Illinois at Urbana−Champaign, Vandoeuvre-les-Nancy F-54506, France
- Department
of Physics, University of Illinois at Urbana−Champaign, 1110 West Green Street, Urbana, Illinois 61801, United States
| | - François Dehez
- SRSMC, UMR 7019 Université de Lorraine CNRS, Vandoeuvre-les-Nancy F-54500, France
- Laboratoire
International Associé CNRS and University of Illinois at Urbana−Champaign, Vandoeuvre-les-Nancy F-54506, France
| | - Jason R. Schnell
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Nicole Zitzmann
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | | | - Laurent J. Catoire
- Laboratory
of Biology and Physico-Chemistry of Membrane Proteins, Institut de Biologie Physico-Chimique (IBPC), UMR
7099 CNRS, Paris 75005, France
- University
Paris Diderot, Paris 75005, France
- PSL
Research University, Paris 75005, France
| | - Bruno Miroux
- Laboratory
of Biology and Physico-Chemistry of Membrane Proteins, Institut de Biologie Physico-Chimique (IBPC), UMR
7099 CNRS, Paris 75005, France
- University
Paris Diderot, Paris 75005, France
- PSL
Research University, Paris 75005, France
| | - Edmund R. S. Kunji
- Medical
Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Gianluigi Veglia
- Department
of Biochemistry, Molecular Biology, and Biophysics, and Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Timothy A. Cross
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Paul Schanda
- Université
Grenoble Alpes, CEA, CNRS, IBS, Grenoble F-38000, France
| |
Collapse
|
70
|
Kourkoulou A, Pittis AA, Diallinas G. Evolution of substrate specificity in the Nucleobase-Ascorbate Transporter (NAT) protein family. MICROBIAL CELL 2018; 5:280-292. [PMID: 29850465 PMCID: PMC5972032 DOI: 10.15698/mic2018.06.636] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
L-ascorbic acid (vitamin C) is an essential metabolite in animals and plants due to its role as an enzyme co-factor and antioxidant activity. In most eukaryotic organisms, L-ascorbate is biosynthesized enzymatically, but in several major groups, including the primate suborder Haplorhini, this ability is lost due to gene truncations in the gene coding for L-gulonolactone oxidase. Specific ascorbate transporters (SVCTs) have been characterized only in mammals and shown to be essential for life. These belong to an extensively studied transporter family, called Nucleobase-Ascorbate Transporters (NAT). The prototypic member of this family, and one of the most extensively studied eukaryotic transporters, is UapA, a uric acid-xanthine/H+ symporter in the fungus Aspergillus nidulans. Here, we investigate molecular aspects of NAT substrate specificity and address the evolution of ascorbate transporters apparently from ancestral nucleobase transporters. We present a phylogenetic analysis, identifying a distinct NAT clade that includes all known L-ascorbate transporters. This clade includes homologues only from vertebrates, and has no members in non-vertebrate or microbial eukaryotes, plants or prokaryotes. Additionally, we identify within the substrate-binding site of NATs a differentially conserved motif, which we propose is critical for nucleobase versus ascorbate recognition. This conclusion is supported by the amino acid composition of this motif in distinct phylogenetic clades and mutational analysis in the UapA transporter. Together with evidence obtained herein that UapA can recognize with extremely low affinity L-ascorbate, our results support that ascorbate-specific NATs evolved by optimization of a sub-function of ancestral nucleobase transporters.
Collapse
Affiliation(s)
- Anezia Kourkoulou
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, Athens 15784, Greece
| | | | - George Diallinas
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, Athens 15784, Greece
| |
Collapse
|
71
|
Botou M, Lazou P, Papakostas K, Lambrinidis G, Evangelidis T, Mikros E, Frillingos S. Insight on specificity of uracil permeases of the NAT/NCS2 family from analysis of the transporter encoded in the pyrimidine utilization operon ofEscherichia coli. Mol Microbiol 2018; 108:204-219. [DOI: 10.1111/mmi.13931] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/12/2018] [Indexed: 02/06/2023]
Affiliation(s)
- Maria Botou
- Laboratory of Biological Chemistry Department of Medicine School of Health Sciences; University of Ioannina; Ioannina Greece
| | - Panayiota Lazou
- Laboratory of Biological Chemistry Department of Medicine School of Health Sciences; University of Ioannina; Ioannina Greece
| | - Konstantinos Papakostas
- Laboratory of Biological Chemistry Department of Medicine School of Health Sciences; University of Ioannina; Ioannina Greece
| | - George Lambrinidis
- Division of Pharmaceutical Chemistry Department of Pharmacy School of Health Sciences; National and Kapodistrian University of Athens; Athens Greece
| | - Thomas Evangelidis
- Division of Pharmaceutical Chemistry Department of Pharmacy School of Health Sciences; National and Kapodistrian University of Athens; Athens Greece
| | - Emmanuel Mikros
- Division of Pharmaceutical Chemistry Department of Pharmacy School of Health Sciences; National and Kapodistrian University of Athens; Athens Greece
| | - Stathis Frillingos
- Laboratory of Biological Chemistry Department of Medicine School of Health Sciences; University of Ioannina; Ioannina Greece
| |
Collapse
|
72
|
Huynh KW, Jiang J, Abuladze N, Tsirulnikov K, Kao L, Shao X, Newman D, Azimov R, Pushkin A, Zhou ZH, Kurtz I. CryoEM structure of the human SLC4A4 sodium-coupled acid-base transporter NBCe1. Nat Commun 2018; 9:900. [PMID: 29500354 PMCID: PMC5834491 DOI: 10.1038/s41467-018-03271-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 02/01/2018] [Indexed: 12/19/2022] Open
Abstract
Na+-coupled acid-base transporters play essential roles in human biology. Their dysfunction has been linked to cancer, heart, and brain disease. High-resolution structures of mammalian Na+-coupled acid-base transporters are not available. The sodium-bicarbonate cotransporter NBCe1 functions in multiple organs and its mutations cause blindness, abnormal growth and blood chemistry, migraines, and impaired cognitive function. Here, we have determined the structure of the membrane domain dimer of human NBCe1 at 3.9 Å resolution by cryo electron microscopy. Our atomic model and functional mutagenesis revealed the ion accessibility pathway and the ion coordination site, the latter containing residues involved in human disease-causing mutations. We identified a small number of residues within the ion coordination site whose modification transformed NBCe1 into an anion exchanger. Our data suggest that symporters and exchangers utilize comparable transport machinery and that subtle differences in their substrate-binding regions have very significant effects on their transport mode.
Collapse
Affiliation(s)
- Kevin W Huynh
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA
| | - Jiansen Jiang
- California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, CA, 90095, USA
| | - Natalia Abuladze
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA
| | - Kirill Tsirulnikov
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA
| | - Liyo Kao
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA
| | - Xuesi Shao
- Department of Neurobiology, University of California, Los Angeles, CA, 90095, USA
| | - Debra Newman
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA
| | - Rustam Azimov
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA
| | - Alexander Pushkin
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA.
| | - Z Hong Zhou
- California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA.
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, CA, 90095, USA.
| | - Ira Kurtz
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA.
- Brain Research Institute, University of California, Los Angeles, CA, 90095, USA.
| |
Collapse
|
73
|
Alexander CR, Dingman DW, Schultes NP, Mourad GS. The solute transport profile of two Aza-guanine transporters from the Honey bee pathogen Paenibacillus larvae. FEMS Microbiol Lett 2018; 365:4828326. [DOI: 10.1093/femsle/fny018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 01/26/2018] [Indexed: 01/05/2023] Open
Affiliation(s)
- Candace R Alexander
- Department of Biology, Indiana University-Purdue University Fort Wayne, 2101 East Coliseum Blvd., Fort Wayne, IN 46805, USA
| | - Douglas W Dingman
- Department of Entomology, The Connecticut Agricultural Experiment Station, 123 Huntington St, New Haven, CT 06511, USA
| | - Neil P Schultes
- Department of Plant Pathology & Ecology, The Connecticut Agricultural Experiment Station, 123 Huntington St, New Haven, CT 06511, USA
| | - George S Mourad
- Department of Biology, Indiana University-Purdue University Fort Wayne, 2101 East Coliseum Blvd., Fort Wayne, IN 46805, USA
| |
Collapse
|
74
|
Atzrodt J, Derdau V, Kerr WJ, Reid M. Deuterium- und tritiummarkierte Verbindungen: Anwendungen in den modernen Biowissenschaften. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201704146] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Jens Atzrodt
- Isotope Chemistry and Metabolite Synthesis, Integrated Drug Discovery, Medicinal Chemistry; Industriepark Höchst, G876 65926 Frankfurt Deutschland
| | - Volker Derdau
- Isotope Chemistry and Metabolite Synthesis, Integrated Drug Discovery, Medicinal Chemistry; Industriepark Höchst, G876 65926 Frankfurt Deutschland
| | - William J. Kerr
- Department of Pure and Applied Chemistry, WestCHEM; University of Strathclyde; 295 Cathedral Street Glasgow Scotland G1 1XL Großbritannien
| | - Marc Reid
- Department of Pure and Applied Chemistry, WestCHEM; University of Strathclyde; 295 Cathedral Street Glasgow Scotland G1 1XL Großbritannien
| |
Collapse
|
75
|
Atzrodt J, Derdau V, Kerr WJ, Reid M. Deuterium- and Tritium-Labelled Compounds: Applications in the Life Sciences. Angew Chem Int Ed Engl 2018; 57:1758-1784. [PMID: 28815899 DOI: 10.1002/anie.201704146] [Citation(s) in RCA: 403] [Impact Index Per Article: 67.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 07/27/2017] [Indexed: 12/19/2022]
Abstract
Hydrogen isotopes are unique tools for identifying and understanding biological and chemical processes. Hydrogen isotope labelling allows for the traceless and direct incorporation of an additional mass or radioactive tag into an organic molecule with almost no changes in its chemical structure, physical properties, or biological activity. Using deuterium-labelled isotopologues to study the unique mass-spectrometric patterns generated from mixtures of biologically relevant molecules drastically simplifies analysis. Such methods are now providing unprecedented levels of insight in a wide and continuously growing range of applications in the life sciences and beyond. Tritium (3 H), in particular, has seen an increase in utilization, especially in pharmaceutical drug discovery. The efforts and costs associated with the synthesis of labelled compounds are more than compensated for by the enhanced molecular sensitivity during analysis and the high reliability of the data obtained. In this Review, advances in the application of hydrogen isotopes in the life sciences are described.
Collapse
Affiliation(s)
- Jens Atzrodt
- Isotope Chemistry and Metabolite Synthesis, Integrated Drug Discovery, Medicinal Chemistry, Industriepark Höchst, G876, 65926, Frankfurt, Germany
| | - Volker Derdau
- Isotope Chemistry and Metabolite Synthesis, Integrated Drug Discovery, Medicinal Chemistry, Industriepark Höchst, G876, 65926, Frankfurt, Germany
| | - William J Kerr
- Department of Pure and Applied Chemistry, WestCHEM, University of Strathclyde, 295 Cathedral Street, Glasgow, Scotland, G1 1XL, UK
| | - Marc Reid
- Department of Pure and Applied Chemistry, WestCHEM, University of Strathclyde, 295 Cathedral Street, Glasgow, Scotland, G1 1XL, UK
| |
Collapse
|
76
|
Ficici E, Faraldo-Gómez JD, Jennings ML, Forrest LR. Asymmetry of inverted-topology repeats in the AE1 anion exchanger suggests an elevator-like mechanism. J Gen Physiol 2017; 149:1149-1164. [PMID: 29167180 PMCID: PMC5715908 DOI: 10.1085/jgp.201711836] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 10/10/2017] [Indexed: 12/02/2022] Open
Abstract
Anion exchanger 1 catalyzes the transmembrane antiport of chloride and bicarbonate ions through a mechanism that has remained unclear. By modeling its inward-facing state and comparing it with the known outward-facing form, Ficici et al. hypothesize that this transporter features an elevator-like mechanism. The membrane transporter anion exchanger 1 (AE1), or band 3, is a key component in the processes of carbon-dioxide transport in the blood and urinary acidification in the renal collecting duct. In both erythrocytes and the basolateral membrane of the collecting-duct α-intercalated cells, the role of AE1 is to catalyze a one-for-one exchange of chloride for bicarbonate. After decades of biochemical and functional studies, the structure of the transmembrane region of AE1, which catalyzes the anion-exchange reaction, has finally been determined. Each protomer of the AE1 dimer comprises two repeats with inverted transmembrane topologies, but the structures of these repeats differ. This asymmetry causes the putative substrate-binding site to be exposed only to the extracellular space, consistent with the expectation that anion exchange occurs via an alternating-access mechanism. Here, we hypothesize that the unknown, inward-facing conformation results from inversion of this asymmetry, and we propose a model of this state constructed using repeat-swap homology modeling. By comparing this inward-facing model with the outward-facing experimental structure, we predict that the mechanism of AE1 involves an elevator-like motion of the substrate-binding domain relative to the nearly stationary dimerization domain and to the membrane plane. This hypothesis is in qualitative agreement with a wide range of biochemical and functional data, which we review in detail, and suggests new avenues of experimentation.
Collapse
Affiliation(s)
- Emel Ficici
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD
| | - José D Faraldo-Gómez
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Michael L Jennings
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Lucy R Forrest
- Computational Structural Biology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| |
Collapse
|
77
|
Tsirigos KD, Govindarajan S, Bassot C, Västermark Å, Lamb J, Shu N, Elofsson A. Topology of membrane proteins-predictions, limitations and variations. Curr Opin Struct Biol 2017; 50:9-17. [PMID: 29100082 DOI: 10.1016/j.sbi.2017.10.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 09/29/2017] [Accepted: 10/03/2017] [Indexed: 10/18/2022]
Abstract
Transmembrane proteins perform a variety of important biological functions necessary for the survival and growth of the cells. Membrane proteins are built up by transmembrane segments that span the lipid bilayer. The segments can either be in the form of hydrophobic alpha-helices or beta-sheets which create a barrel. A fundamental aspect of the structure of transmembrane proteins is the membrane topology, that is, the number of transmembrane segments, their position in the protein sequence and their orientation in the membrane. Along these lines, many predictive algorithms for the prediction of the topology of alpha-helical and beta-barrel transmembrane proteins exist. The newest algorithms obtain an accuracy close to 80% both for alpha-helical and beta-barrel transmembrane proteins. However, lately it has been shown that the simplified picture presented when describing a protein family by its topology is limited. To demonstrate this, we highlight examples where the topology is either not conserved in a protein superfamily or where the structure cannot be described solely by the topology of a protein. The prediction of these non-standard features from sequence alone was not successful until the recent revolutionary progress in 3D-structure prediction of proteins.
Collapse
Affiliation(s)
| | - Sudha Govindarajan
- Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden; Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Claudio Bassot
- Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden; Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Åke Västermark
- Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden; Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden; NITECH, Showa-Ku, Nagoya 466-8555 Japan
| | - John Lamb
- Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden; Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Nanjiang Shu
- Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden; Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden; National Bioinformatics Infrastructure, Sweden; Nordic e-Infrastructure Collaboration, Sweden
| | - Arne Elofsson
- Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden; Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden; Swedish e-Science Research Center (SeRC), Sweden.
| |
Collapse
|
78
|
Leelakanok N, Geary S, Salem A. Fabrication and Use of Poly(d,l-lactide-co-glycolide)-Based Formulations Designed for Modified Release of 5-Fluorouracil. J Pharm Sci 2017; 107:513-528. [PMID: 29045885 DOI: 10.1016/j.xphs.2017.10.012] [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: 07/15/2017] [Revised: 10/03/2017] [Accepted: 10/06/2017] [Indexed: 12/14/2022]
Abstract
5-fluorouracil (5-FU) is a chemotherapeutic agent that has been used for the treatment of a variety of malignancies since its initial introduction to the clinic in 1957. Owing to its short biological half-life, multiple dosings are generally required to maintain effective 5-FU plasma concentrations throughout the therapeutic period. Clinical studies have shown that continuous 5-FU administration is generally superior to bolus injection as exhibited by lower toxicities and increased therapeutic efficacy. Optimal therapeutic efficacy, however, is often compromised by the limiting therapeutic index. Whilst oral formulations are also used, these suffer from the drawbacks of variable bioavailability and first-pass metabolism. As a result, sustained release formulations of 5-FU have been investigated in an effort to mimic the kinetics of continuous infusion particularly for situations where local delivery is considered appropriate. The biocompatible, biodegradable, and highly tunable synthetic polymer, poly(d,l-lactide-co-glycolide) (PLGA), is widely used as a vector for sustained drug delivery, however, issues such as insufficient loading and inappropriate burst release kinetics have dogged progress into the clinic for small hydrophilic drugs such as 5-FU. This review provides introductory information about the mechanism of action, pharmacokinetic and physicochemical properties, and clinical use of 5-FU that have contributed to the development of PLGA-based 5-FU release platforms. In addition, this review provides information on fabrication methods used for a range of 5-FU-loaded PLGA formulations and discusses factors affecting the release kinetics of 5-FU as well as the in vitro and in vivo antitumor or antiproliferative efficacy of these platforms.
Collapse
Affiliation(s)
- Nattawut Leelakanok
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, Iowa City, Iowa 52242
| | - Sean Geary
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, Iowa City, Iowa 52242
| | - Aliasger Salem
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, Iowa City, Iowa 52242.
| |
Collapse
|
79
|
Rapp C, Bai X, Reithmeier RAF. Molecular analysis of human solute carrier SLC26 anion transporter disease-causing mutations using 3-dimensional homology modeling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:2420-2434. [PMID: 28941661 DOI: 10.1016/j.bbamem.2017.09.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 06/08/2017] [Accepted: 09/14/2017] [Indexed: 12/22/2022]
Abstract
The availability of the first crystal structure of a bacterial member (SLC26Dg) of the solute carrier SLC26 family of anion transporters has allowed us to create 3-dimensional models of all 10 human members (SLC26A1-A11, A10 being a pseudogene) of these membrane proteins using the Phyre2 bioinformatic tool. The homology modeling predicted that the SLC26 human proteins, like the SLC26Dg template, all consist of 14 transmembrane segments (TM) arranged in a 7+7 inverted topology with the amino-termini of two half-helices (TM3 and 10) facing each other in the centre of the protein to create the anion-binding site, linked to a C-terminal cytosolic sulfate transporter anti-sigma factor antagonist (STAS) domain. A plethora of human diseases are associated with mutations in the genes encoding human SLC26 transporters, including chondrodysplasias with varying severity in SLC26A2 (~50 mutations, 27 point mutations), congenital chloride-losing diarrhea in SLC26A3 (~70 mutations, 31 point mutations) and Pendred Syndrome or deafness autosomal recessive type 4 in SLC26A4 (~500 mutations, 203 point mutations). We have localized all of these point mutations in the 3-dimensional structures of the respective SLC26A2, A3 and A4 proteins and systematically analyzed their effect on protein structure. While most disease-causing mutations may cause folding defects resulting in impaired trafficking of these membrane glycoproteins from the endoplasmic reticulum to the cell surface - as demonstrated in a number of functional expression studies - the modeling also revealed that a number of pathogenic mutations are localized to the anion-binding site, which may directly affect transport function.
Collapse
Affiliation(s)
- Chloe Rapp
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Xiaoyun Bai
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | | |
Collapse
|
80
|
Abstract
Membrane transporter proteins are critical for cellular uptake and export of molecules, and are reported to function by a number of different molecular mechanisms. The new occluded state structure of the uracil transporter, UraA, from Escherichia coli, reveals that both coordinated movement of the two domains of a single protomer together with dimer formation are important for transport activity.
Collapse
Affiliation(s)
- Bernadette Byrne
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| |
Collapse
|
81
|
Transporter oligomerization: form and function. Biochem Soc Trans 2017; 44:1737-1744. [PMID: 27913684 PMCID: PMC5134999 DOI: 10.1042/bst20160217] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/16/2016] [Accepted: 09/19/2016] [Indexed: 12/22/2022]
Abstract
Transporters are integral membrane proteins with central roles in the efficient movement of molecules across biological membranes. Many transporters exist as oligomers in the membrane. Depending on the individual transport protein, oligomerization can have roles in membrane trafficking, function, regulation and turnover. For example, our recent studies on UapA, a nucleobase ascorbate transporter, from Aspergillus nidulans, have revealed both that dimerization of this protein is essential for correct trafficking to the membrane and the structural basis of how one UapA protomer can affect the function of the closely associated adjacent protomer. Here, we review the roles of oligomerization in many particularly well-studied transporters and transporter families.
Collapse
|
82
|
Chang YN, Geertsma ER. The novel class of seven transmembrane segment inverted repeat carriers. Biol Chem 2017; 398:165-174. [PMID: 27865089 DOI: 10.1515/hsz-2016-0254] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 11/16/2016] [Indexed: 12/31/2022]
Abstract
Solute carriers from the SLC4, SLC23, and SLC26 families are involved in pH regulation, vitamin C transport and ion homeostasis. While these families do not share any obvious sequence relationship, they are united by their unique and novel architecture. Each member of this structural class is organized into two structurally related halves of seven transmembrane segments each. These halves span the membrane with opposite orientations and form an intricately intertwined structure of two inverted repeats. This review highlights the general design principles of this fold and reveals the diversity between the different families. We discuss their domain architecture, structural framework and transport mode and detail an initial transport mechanism for this fold inferred from the recently solved structures of different members.
Collapse
|
83
|
Dimeric structure of the uracil:proton symporter UraA provides mechanistic insights into the SLC4/23/26 transporters. Cell Res 2017. [PMID: 28621327 PMCID: PMC5539350 DOI: 10.1038/cr.2017.83] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The Escherichia coli uracil:proton symporter UraA is a prototypical member of the nucleobase/ascorbate transporter (NAT) or nucleobase/cation symporter 2 (NCS2) family, which corresponds to the human solute carrier family SLC23. UraA consists of 14 transmembrane segments (TMs) that are organized into two distinct domains, the core domain and the gate domain, a structural fold that is also shared by the SLC4 and SLC26 transporters. Here we present the crystal structure of UraA bound to uracil in an occluded state at 2.5 Å resolution. Structural comparison with the previously reported inward-open UraA reveals pronounced relative motions between the core domain and the gate domain as well as intra-domain rearrangement of the gate domain. The occluded UraA forms a dimer in the structure wherein the gate domains are sandwiched by two core domains. In vitro and in vivo biochemical characterizations show that UraA is at equilibrium between dimer and monomer in all tested detergent micelles, while dimer formation is necessary for the transport activity. Structural comparison between the dimeric UraA and the recently reported inward-facing dimeric UapA provides important insight into the transport mechanism of SLC23 transporters.
Collapse
|
84
|
Bai JP, Moeini-Naghani I, Zhong S, Li FY, Bian S, Sigworth FJ, Santos-Sacchi J, Navaratnam D. Current carried by the Slc26 family member prestin does not flow through the transporter pathway. Sci Rep 2017; 7:46619. [PMID: 28422190 PMCID: PMC5395958 DOI: 10.1038/srep46619] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 03/21/2017] [Indexed: 01/01/2023] Open
Abstract
Prestin in the lateral membrane of outer hair cells, is responsible for electromotility (EM) and a corresponding nonlinear capacitance (NLC). Prestin’s voltage sensitivity is influenced by intracellular chloride. A regulator of intracellular chloride is a stretch-sensitive, non-selective conductance within the lateral membrane, GmetL. We determine that prestin itself possesses a stretch-sensitive, non-selective conductance that is largest in the presence of thiocyanate ions. This conductance is independent of the anion transporter mechanism. Prestin has been modeled, based on structural data from related anion transporters (SLC26Dg and UraA), to have a 7 + 7 inverted repeat structure with anion transport initiated by chloride binding at the intracellular cleft. Mutation of residues that bind intracellular chloride, and salicylate treatment which prevents chloride binding, have no effect on thiocyanate conductance. In contrast, other mutations reduce the conductance while preserving NLC. When superimposed on prestin’s structure, the location of these mutations indicates that the ion permeation pathway lies between the core and gate ring of helices, distinct from the transporter pathway. The uncoupled current is reminiscent of an omega current in voltage-gated ion channels. We suggest that prestin itself is the main regulator of intracellular chloride concentration via a route distinct from its transporter pathway.
Collapse
Affiliation(s)
- Jun-Ping Bai
- Dept. of Neurology, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510 USA
| | - Iman Moeini-Naghani
- Dept. of Neurology, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510 USA
| | - Sheng Zhong
- Dept. of Surgery, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510 USA
| | - Fang-Yong Li
- Yale Center for Analytical Sciences, Yale School of Public Health, 300 George St., Ste Suite 555, New Haven, CT 06511, USA
| | - Shumin Bian
- Dept. of Neurology, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510 USA
| | - Fred J Sigworth
- Dept. of Cellular and Molecular Physiology, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA
| | - Joseph Santos-Sacchi
- Dept. of Surgery, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510 USA.,Dept. of Cellular and Molecular Physiology, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA.,Dept. of, Neuroscience, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA
| | - Dhasakumar Navaratnam
- Dept. of Neurology, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510 USA.,Dept. of Surgery, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510 USA.,Dept. of, Neuroscience, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA
| |
Collapse
|
85
|
Chen C, Hou X, Utkina N, Danilov L, Zhou D, Torgov V, Veselovsky V, Liu B, Feng L. Identification and biochemical characterization of a novel α-1,3-mannosyltransferase WfcD from Escherichia coli O141. Carbohydr Res 2017; 443-444:78-86. [PMID: 28402841 DOI: 10.1016/j.carres.2017.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 03/31/2017] [Accepted: 04/02/2017] [Indexed: 11/30/2022]
Abstract
Glycosyltransferases (GTs) catalyze the formation of regio- and stereospecific glycosidic linkages between specific sugar donors and recipients. In this study, the function of the wfcD gene from the Escherichia coli O141 O-antigen gene cluster encoding an α-1,3-mannosyltransferase that catalyzed the formation of the linkage Man(α1-3)-GlcNAc was biochemically characterized. WfcD was expressed in E. coli BL21 (DE3), and the enzymatic product was identified by liquid chromatography-mass spectrometry (LC-MS), collision-induced dissociation electrospray ionization ion trap multiple tandem MS (CID-ESI-IT-MSn) and glycosidase digestion using the donor substrate GDP-Man and the synthetic acceptor substrate decyl diphosphate 2-acetamido-2-deoxy-α-D-glucopyranose (GlcNAc-PP-De). The kinetic and physiochemical properties and the substrate specificity of WfcD were investigated. WfcD is the first characterized bacterial mannosyltransferase that acts on the Man(α1-3)-GlcNAc linkage. This study enhances our knowledge of the diverse functions of GTs.
Collapse
Affiliation(s)
- Chao Chen
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin, 300457, PR China; The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin, 300457, PR China
| | - Xi Hou
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin, 300457, PR China; The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin, 300457, PR China
| | - Natalia Utkina
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Leonid Danilov
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Dawei Zhou
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin, 300457, PR China; The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin, 300457, PR China
| | - Vladimir Torgov
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Vladimir Veselovsky
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Bin Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin, 300457, PR China; The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin, 300457, PR China
| | - Lu Feng
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin, 300457, PR China; The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin, 300457, PR China.
| |
Collapse
|
86
|
Barraco-Vega M, Romero H, Richero M, Cerdeiras MP, Cecchetto G. Functional characterization of two novel purine transporters from the Basidiomycota Phanerochaete chrysosporium. Gene 2017; 601:1-10. [PMID: 27923672 DOI: 10.1016/j.gene.2016.11.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 11/07/2016] [Accepted: 11/17/2016] [Indexed: 12/24/2022]
Abstract
Purine transporters as substrate entry points in organisms, are involved in a number of cellular processes such as nitrogen source uptake, energy metabolism and synthesis of nucleic acids. In this study, two nucleobase transporter genes (phZ, phU) from Phanerochaete chrysosporium were cloned, identified, and functionally characterized. Our results show that PhZ is a transporter of adenine and hypoxanthine, and a protein belonging to the AzgA-like family, whilst PhU belongs to the NAT/NCS2 family, transporting xanthine and uric acid. No other sequences belonging to these families were detected in P. chrysosporium's genome. Phylogenetic analyses show that AzgA-like sequences form monophyletic groups for each major lineage (Ascomycota, Basidiomycota and Zygomycota). In contrast, Ascomycota and Basidiomycota NAT/NCS2 sequences do not form monophyletic groups and several copies of this protein are distributed across the tree. Expression of phU was significantly downregulated in the presence of a primary source like ammonium, and enhanced if purines were present or if the mycelium was nitrogen starved. phZ was clearly induced by its substrates (hypoxanthine, adenine), very lightly induced by xanthine, suppressed by urea and amino acids and expressed at a basal level when uric acid or ammonium was the nitrogen source or when the mycelium was starved for nitrogen. In order to perform substrate analyses, both P. chrysosporium proteins (PhZ, PhU) were expressed in Aspergillus nidulans. Epifluorescent microscopy showed that under inducing conditions, PhZ-GFP and PhU-GFP were present at the plasma membrane of A. nidulans transformed strains, and were internalized in repressed conditions. Our results suggest that in the white-rot fungus P. chrysosporium, phU has a catabolic role and phZ, (less dependent of the nitrogen source), plays a key role in purine acquisition to provide biosynthetic components. These are the first purine transporters characterized in Basidiomycota.
Collapse
Affiliation(s)
- Mariana Barraco-Vega
- Microbiología Departamento de Biociencias, Facultad de Química, Universidad de la República, Montevideo 11800, Uruguay.
| | - Héctor Romero
- Laboratorio de Organización y Evolución del Genoma, Departamento de Ecología y Evolución, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay
| | - Mariana Richero
- Microbiología Instituto de Química Biológica, Facultad de Ciencias - Facultad de Química, Universidad de la República, Montevideo 11800, Uruguay
| | - María Pía Cerdeiras
- Microbiología Departamento de Biociencias, Facultad de Química, Universidad de la República, Montevideo 11800, Uruguay
| | - Gianna Cecchetto
- Microbiología Instituto de Química Biológica, Facultad de Ciencias - Facultad de Química, Universidad de la República, Montevideo 11800, Uruguay
| |
Collapse
|
87
|
Badior KE, Alka K, Casey JR. SLC4A11 Three-Dimensional Homology Model Rationalizes Corneal Dystrophy-Causing Mutations. Hum Mutat 2016; 38:279-288. [PMID: 27925686 DOI: 10.1002/humu.23152] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 12/01/2016] [Indexed: 12/17/2022]
Abstract
We studied the structural effects of point mutations of a membrane protein that cause genetic disease. SLC4A11 is a membrane transport protein (OH- /H+ /NH3 /H2 O) of basolateral corneal endothelium, whose mutations cause some cases of congenital hereditary endothelial dystrophy and Fuchs endothelial corneal dystrophy. We created a three-dimensional homology model of SLC4A11 membrane domain, using Band 3 (SLC4A1) crystal structure as template. The homology model was assessed in silico and by analysis of mutants designed on the basis of the model. Catalytic pathway mutants p.Glu675Gln, p.His724Arg, and p.His724Ala impaired SLC4A11 transport. p.Ala720Leu, in a region of extended structure of the proposed translocation pore, failed to mature to the cell surface. p.Gly509Lys, located in an open region at the core domain/gate domain interface, had wild-type level of transport function. The molecular phenotype of 37 corneal dystrophy-causing point mutants was rationalized, based on their location in the homology model. Four map to the substrate translocation pathway, 25 to regions of close transmembrane helix packing, three to the dimeric interface, and five lie in extramembraneous loops. The model provides a view of the spectrum of effects of disease mutations on membrane protein structure and provides a tool to analyze pathogenicity of additional newly discovered SLC4A11 mutants.
Collapse
Affiliation(s)
- Katherine E Badior
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Kumari Alka
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Joseph R Casey
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| |
Collapse
|
88
|
Coudray N, L Seyler S, Lasala R, Zhang Z, Clark KM, Dumont ME, Rohou A, Beckstein O, Stokes DL. Structure of the SLC4 transporter Bor1p in an inward-facing conformation. Protein Sci 2016; 26:130-145. [PMID: 27717063 DOI: 10.1002/pro.3061] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 10/05/2016] [Accepted: 10/06/2016] [Indexed: 01/05/2023]
Abstract
Bor1p is a secondary transporter in yeast that is responsible for boron transport. Bor1p belongs to the SLC4 family which controls bicarbonate exchange and pH regulation in animals as well as borate uptake in plants. The SLC4 family is more distantly related to members of the Amino acid-Polyamine-organoCation (APC) superfamily, which includes well studied transporters such as LeuT, Mhp1, AdiC, vSGLT, UraA, SLC26Dg. Their mechanism generally involves relative movements of two domains: a core domain that binds substrate and a gate domain that in many cases mediates dimerization. To shed light on conformational changes governing transport by the SLC4 family, we grew helical membrane crystals of Bor1p from Saccharomyces mikatae and determined a structure at ∼6 Å resolution using cryo-electron microscopy. To evaluate the conformation of Bor1p in these crystals, a homology model was built based on the related anion exchanger from red blood cells (AE1). This homology model was fitted to the cryo-EM density map using the Molecular Dynamics (MD) Flexible Fitting method and then relaxed by all-atom MD simulation in explicit solvent and membrane. Mapping of water accessibility indicates that the resulting structure represents an inward-facing conformation. Comparisons of the resulting Bor1p model with the X-ray structure of AE1 in an outward-facing conformation, together with MD simulations of inward-facing and outward-facing Bor1p models, suggest rigid body movements of the core domain relative to the gate domain. These movements are consistent with the rocking-bundle transport mechanism described for other members of the APC superfamily.
Collapse
Affiliation(s)
- Nicolas Coudray
- Skirball Institute for Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, New York, 10016
| | - Sean L Seyler
- Department of Physics, Arizona State University, Tempe, Arizona, 85287
| | - Ralph Lasala
- Skirball Institute for Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, New York, 10016
| | - Zhening Zhang
- Skirball Institute for Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, New York, 10016
| | - Kathy M Clark
- Department of Pediatrics, University of Rochester Medical Center, Rochester, New York, 14652
| | - Mark E Dumont
- Department of Pediatrics, University of Rochester Medical Center, Rochester, New York, 14652.,Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York, 14652
| | - Alexis Rohou
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, 20147
| | - Oliver Beckstein
- Department of Physics, Arizona State University, Tempe, Arizona, 85287.,Center for Biological Physics, Arizona State University, Tempe, Arizona, 85287
| | - David L Stokes
- Skirball Institute for Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, New York, 10016
| |
Collapse
|
89
|
Mapping pathogenic mutations suggests an innovative structural model for the pendrin (SLC26A4) transmembrane domain. Biochimie 2016; 132:109-120. [PMID: 27771369 DOI: 10.1016/j.biochi.2016.10.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 10/03/2016] [Indexed: 12/16/2022]
Abstract
Human pendrin (SLC26A4) is an anion transporter mostly expressed in the inner ear, thyroid and kidney. SLC26A4 gene mutations are associated with a broad phenotypic spectrum, including Pendred Syndrome and non-syndromic hearing loss with enlarged vestibular aqueduct (ns-EVA). No experimental structure of pendrin is currently available, making phenotype-genotype correlations difficult as predictions of transmembrane (TM) segments vary in number. Here, we propose a novel three-dimensional (3D) pendrin transmembrane domain model based on the SLC26Dg transporter. The resulting 14 TM topology was found to include two non-canonical transmembrane segments crucial for pendrin activity. Mutation mapping of 147 clinically validated pathological mutations shows that most affect two previously undescribed TM regions.
Collapse
|
90
|
Structure of Bor1 supports an elevator transport mechanism for SLC4 anion exchangers. Proc Natl Acad Sci U S A 2016; 113:10542-6. [PMID: 27601653 DOI: 10.1073/pnas.1612603113] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Boron is essential for plant growth because of its incorporation into plant cell walls; however, in excess it is toxic to plants. Boron transport and homeostasis in plants is regulated in part by the borate efflux transporter Bor1, a member of the solute carrier (SLC) 4 transporter family with homology to the human bicarbonate transporter Band 3. Here, we present the 4.1-Å resolution crystal structure of Arabidopsis thaliana Bor1. The structure displays a dimeric architecture in which dimerization is mediated by centralized Gate domains. Comparisons with a structure of Band 3 in an outward-open state reveal that the Core domains of Bor1 have rotated inwards to achieve an occluded state. Further structural comparisons with UapA, a xanthine transporter from the nucleobase-ascorbate transporter family, show that the downward pivoting of the Core domains relative to the Gate domains may access an inward-open state. These results suggest that the SLC4, SLC26, and nucleobase-ascorbate transporter families all share an elevator transport mechanism in which alternating access is provided by Core domains that carry substrates across a membrane.
Collapse
|
91
|
Dissection of Transporter Function: From Genetics to Structure. Trends Genet 2016; 32:576-590. [DOI: 10.1016/j.tig.2016.06.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 06/20/2016] [Accepted: 06/21/2016] [Indexed: 12/20/2022]
|
92
|
Zhang T, Gu Y, Fan H. Effect of impurities and post-experimental purification in SAD phasing with serial femtosecond crystallography data. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2016; 72:789-94. [PMID: 27303799 DOI: 10.1107/s205979831600646x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 04/16/2016] [Indexed: 11/10/2022]
Abstract
In serial crystallography (SX) with either an X-ray free-electron laser (XFEL) or synchrotron radiation as the light source, huge numbers of micrometre-sized crystals are used in diffraction data collection. For a SAD experiment using a derivative with introduced heavy atoms, it is difficult to completely exclude crystals of the native protein from the sample. In this paper, simulations were performed to study how the inclusion of native crystals in the derivative sample could affect the result of SAD phasing and how the post-experimental purification proposed by Zhang et al. [(2015), Acta Cryst. D71, 2513-2518] could be used to remove the impurities. A gadolinium derivative of lysozyme and the corresponding native protein were used in the test. Serial femtosecond crystallography (SFX) diffraction snapshots were generated by CrystFEL. SHELXC/D, Phaser, DM, ARP/wARP and REFMAC were used for automatic structure solution. It is shown that a small amount of impurities (snapshots from native crystals) in the set of derivative snapshots can strongly affect the SAD phasing results. On the other hand, post-experimental purification can efficiently remove the impurities, leading to results similar to those from a pure sample.
Collapse
Affiliation(s)
- Tao Zhang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Yuanxin Gu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Haifu Fan
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| |
Collapse
|
93
|
Affiliation(s)
- David Drew
- Centre for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden;
| | - Olga Boudker
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065;
| |
Collapse
|
94
|
Coudray N, Lasala R, Zhang Z, Clark KM, Dumont ME, Stokes DL. Deducing the symmetry of helical assemblies: Applications to membrane proteins. J Struct Biol 2016; 195:167-178. [PMID: 27255388 DOI: 10.1016/j.jsb.2016.05.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 05/26/2016] [Accepted: 05/27/2016] [Indexed: 11/30/2022]
Abstract
Helical reconstruction represents a convenient and powerful approach for structure determination of macromolecules that assemble into helical arrays. In the case of membrane proteins, formation of tubular crystals with helical symmetry represents an attractive alternative, especially when their small size precludes the use of single-particle analysis. An essential first step for helical reconstruction is to characterize the helical symmetry. This process is often daunting, due to the complexity of helical diffraction and to the low signal-to-noise ratio in images of individual assemblies. Furthermore, the large diameters of the tubular crystals produced by membrane proteins exacerbates the innate ambiguities that, if not resolved, will produce incorrect structures. In this report, we describe a set of tools that can be used to eliminate ambiguities and to validate the choice of symmetry. The first approach increases the signal-to-noise ratio along layer lines by incoherently summing data from multiple helical assemblies, thus producing several candidate indexing schemes. The second approach compares the layer lines from images with those from synthetic models built with the various candidate schemes. The third approach uses unit cell dimensions measured from collapsed tubes to distinguish between these candidate schemes. These approaches are illustrated with tubular crystals from a boron transporter from yeast, Bor1p, and a β-barrel channel from the outer membrane of E. coli, OmpF.
Collapse
Affiliation(s)
- Nicolas Coudray
- Skirball Institute for Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, NY 10016, United States
| | - Ralph Lasala
- Skirball Institute for Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, NY 10016, United States
| | - Zhening Zhang
- Skirball Institute for Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, NY 10016, United States
| | - Kathy M Clark
- Department of Pediatrics and Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY 14652, United States
| | - Mark E Dumont
- Department of Pediatrics and Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY 14652, United States
| | - David L Stokes
- Skirball Institute for Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, NY 10016, United States
| |
Collapse
|
95
|
Structure of eukaryotic purine/H(+) symporter UapA suggests a role for homodimerization in transport activity. Nat Commun 2016; 7:11336. [PMID: 27088252 PMCID: PMC4837479 DOI: 10.1038/ncomms11336] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 03/16/2016] [Indexed: 02/03/2023] Open
Abstract
The uric acid/xanthine H+ symporter, UapA, is a high-affinity purine transporter from the filamentous fungus Aspergillus nidulans. Here we present the crystal structure of a genetically stabilized version of UapA (UapA-G411VΔ1–11) in complex with xanthine. UapA is formed from two domains, a core domain and a gate domain, similar to the previously solved uracil transporter UraA, which belongs to the same family. The structure shows UapA in an inward-facing conformation with xanthine bound to residues in the core domain. Unlike UraA, which was observed to be a monomer, UapA forms a dimer in the crystals with dimer interactions formed exclusively through the gate domain. Analysis of dominant negative mutants is consistent with dimerization playing a key role in transport. We postulate that UapA uses an elevator transport mechanism likely to be shared with other structurally homologous transporters including anion exchangers and prestin. UapA is a uric acid/xanthine H+ symporter from a filamentous fungus. Here, the authors solve the crystal structure of the transporter in complex with xanthine revealing it to be a dimer, and this homodimerisation is proposed to be important for function.
Collapse
|
96
|
Reithmeier RAF, Casey JR, Kalli AC, Sansom MSP, Alguel Y, Iwata S. Band 3, the human red cell chloride/bicarbonate anion exchanger (AE1, SLC4A1), in a structural context. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1507-32. [PMID: 27058983 DOI: 10.1016/j.bbamem.2016.03.030] [Citation(s) in RCA: 127] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/21/2016] [Accepted: 03/29/2016] [Indexed: 02/03/2023]
Abstract
The crystal structure of the dimeric membrane domain of human Band 3(1), the red cell chloride/bicarbonate anion exchanger 1 (AE1, SLC4A1), provides a structural context for over four decades of studies into this historic and important membrane glycoprotein. In this review, we highlight the key structural features responsible for anion binding and translocation and have integrated the following topological markers within the Band 3 structure: blood group antigens, N-glycosylation site, protease cleavage sites, inhibitor and chemical labeling sites, and the results of scanning cysteine and N-glycosylation mutagenesis. Locations of mutations linked to human disease, including those responsible for Southeast Asian ovalocytosis, hereditary stomatocytosis, hereditary spherocytosis, and distal renal tubular acidosis, provide molecular insights into their effect on Band 3 folding. Finally, molecular dynamics simulations of phosphatidylcholine self-assembled around Band 3 provide a view of this membrane protein within a lipid bilayer.
Collapse
Affiliation(s)
- Reinhart A F Reithmeier
- Department of Biochemistry, 1 King's College Circle, University of Toronto, Toronto M5S 1A8, Canada.
| | - Joseph R Casey
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Antreas C Kalli
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Yilmaz Alguel
- Division of Molecular Biosciences, Imperial College London, London, SW7 2AZ, UK
| | - So Iwata
- Division of Molecular Biosciences, Imperial College London, London, SW7 2AZ, UK
| |
Collapse
|
97
|
Abstract
Symmetry is a common feature among natural systems, including protein structures. A strong propensity toward symmetric architectures has long been recognized for water-soluble proteins, and this propensity has been rationalized from an evolutionary standpoint. Proteins residing in cellular membranes, however, have traditionally been less amenable to structural studies, and thus the prevalence and significance of symmetry in this important class of molecules is not as well understood. In the past two decades, researchers have made great strides in this area, and these advances have provided exciting insights into the range of architectures adopted by membrane proteins. These structural studies have revealed a similarly strong bias toward symmetric arrangements, which were often unexpected and which occurred despite the restrictions imposed by the membrane environment on the possible symmetry groups. Moreover, membrane proteins disproportionately contain internal structural repeats resulting from duplication and fusion of smaller segments. This article discusses the types and origins of symmetry in membrane proteins and the implications of symmetry for protein function.
Collapse
Affiliation(s)
- Lucy R Forrest
- Computational Structural Biology Group, Porter Neuroscience Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20852;
| |
Collapse
|
98
|
Arakawa T, Kobayashi-Yurugi T, Alguel Y, Iwanari H, Hatae H, Iwata M, Abe Y, Hino T, Ikeda-Suno C, Kuma H, Kang D, Murata T, Hamakubo T, Cameron AD, Kobayashi T, Hamasaki N, Iwata S. Crystal structure of the anion exchanger domain of human erythrocyte band 3. Science 2015; 350:680-4. [PMID: 26542571 DOI: 10.1126/science.aaa4335] [Citation(s) in RCA: 168] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Anion exchanger 1 (AE1), also known as band 3 or SLC4A1, plays a key role in the removal of carbon dioxide from tissues by facilitating the exchange of chloride and bicarbonate across the plasma membrane of erythrocytes. An isoform of AE1 is also present in the kidney. Specific mutations in human AE1 cause several types of hereditary hemolytic anemias and/or distal renal tubular acidosis. Here we report the crystal structure of the band 3 anion exchanger domain (AE1(CTD)) at 3.5 angstroms. The structure is locked in an outward-facing open conformation by an inhibitor. Comparing this structure with a substrate-bound structure of the uracil transporter UraA in an inward-facing conformation allowed us to identify the anion-binding position in the AE1(CTD), and to propose a possible transport mechanism that could explain why selected mutations lead to disease.
Collapse
Affiliation(s)
- Takatoshi Arakawa
- Japan Science and Technology Agency (JST), Exploratory Research for Advanced Technology (ERATO) Human Receptor Crystallography Project, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. JST, Research Acceleration Program, Membrane Protein Crystallography Project, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. Department of Cell Biology, Kyoto University Faculty of Medicine, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
| | - Takami Kobayashi-Yurugi
- Japan Science and Technology Agency (JST), Exploratory Research for Advanced Technology (ERATO) Human Receptor Crystallography Project, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. Department of Cell Biology, Kyoto University Faculty of Medicine, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yilmaz Alguel
- Division of Molecular Biosciences, Membrane Protein Crystallography group, Imperial College London, London SW7 2AZ, UK. Membrane Protein Laboratory, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Chilton, Oxfordshire OX11 0DE, UK. Research Complex at Harwell Rutherford, Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0FA, UK
| | - Hiroko Iwanari
- Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Hinako Hatae
- Faculty of Pharmaceutical Sciences, Nagasaki International University, 2825-7 Huis Ten Bosch-cho, Sasebo, Nagasaki 859-3298, Japan
| | - Momi Iwata
- Division of Molecular Biosciences, Membrane Protein Crystallography group, Imperial College London, London SW7 2AZ, UK. Membrane Protein Laboratory, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Chilton, Oxfordshire OX11 0DE, UK
| | - Yoshito Abe
- Department of Protein Structure, Function and Design, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Tomoya Hino
- Japan Science and Technology Agency (JST), Exploratory Research for Advanced Technology (ERATO) Human Receptor Crystallography Project, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. Department of Cell Biology, Kyoto University Faculty of Medicine, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
| | - Chiyo Ikeda-Suno
- Japan Science and Technology Agency (JST), Exploratory Research for Advanced Technology (ERATO) Human Receptor Crystallography Project, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. JST, Research Acceleration Program, Membrane Protein Crystallography Project, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. Department of Cell Biology, Kyoto University Faculty of Medicine, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hiroyuki Kuma
- Faculty of Pharmaceutical Sciences, Nagasaki International University, 2825-7 Huis Ten Bosch-cho, Sasebo, Nagasaki 859-3298, Japan
| | - Dongchon Kang
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Takeshi Murata
- Japan Science and Technology Agency (JST), Exploratory Research for Advanced Technology (ERATO) Human Receptor Crystallography Project, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. Department of Cell Biology, Kyoto University Faculty of Medicine, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage, Chiba 263-8522, Japan
| | - Takao Hamakubo
- Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Alexander D Cameron
- Japan Science and Technology Agency (JST), Exploratory Research for Advanced Technology (ERATO) Human Receptor Crystallography Project, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. Division of Molecular Biosciences, Membrane Protein Crystallography group, Imperial College London, London SW7 2AZ, UK. Membrane Protein Laboratory, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Chilton, Oxfordshire OX11 0DE, UK. Research Complex at Harwell Rutherford, Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0FA, UK. School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - Takuya Kobayashi
- Japan Science and Technology Agency (JST), Exploratory Research for Advanced Technology (ERATO) Human Receptor Crystallography Project, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. JST, Research Acceleration Program, Membrane Protein Crystallography Project, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. Department of Cell Biology, Kyoto University Faculty of Medicine, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. Platform for Drug Discovery, Informatics, and Structural Life Science, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
| | - Naotaka Hamasaki
- Faculty of Pharmaceutical Sciences, Nagasaki International University, 2825-7 Huis Ten Bosch-cho, Sasebo, Nagasaki 859-3298, Japan
| | - So Iwata
- Japan Science and Technology Agency (JST), Exploratory Research for Advanced Technology (ERATO) Human Receptor Crystallography Project, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. JST, Research Acceleration Program, Membrane Protein Crystallography Project, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. Department of Cell Biology, Kyoto University Faculty of Medicine, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. Division of Molecular Biosciences, Membrane Protein Crystallography group, Imperial College London, London SW7 2AZ, UK. Membrane Protein Laboratory, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Chilton, Oxfordshire OX11 0DE, UK. Research Complex at Harwell Rutherford, Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0FA, UK. Platform for Drug Discovery, Informatics, and Structural Life Science, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
| |
Collapse
|
99
|
Effect of SLC26 anion transporter disease-causing mutations on the stability of the homologous STAS domain of E. coli DauA (YchM). Biochem J 2015; 473:615-26. [PMID: 26635355 DOI: 10.1042/bj20151025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 12/03/2015] [Indexed: 01/08/2023]
Abstract
The human solute carrier 26 (SLC26) family of anion transporters consists of ten members that are found in various organs in the body including the stomach, intestine, kidney, thyroid and ear where they transport anions including bicarbonate, chloride and sulfate, typically in an exchange mode. Mutations in these genes cause a plethora of diseases such as diastrophic dysplasia affecting sulfate uptake into chondrocytes (SLC26A2), congenital chloride-losing diarrhoea (SLC26A3) affecting chloride secretion in the intestine and Pendred's syndrome (SLC26A4) resulting in hearing loss. To understand how these mutations affect the structures of the SLC26 membrane proteins and their ability to function properly, 12 human disease-causing mutants from SLC26A2, SLC26A3 and SLC26A4 were introduced into the equivalent sites of the sulfate transporter anti-sigma factor antagonist (STAS) domain of a bacterial homologue SLC26 protein DauA (YchM). Biophysical analyses including size-exclusion chromatography, circular dichroism (CD), differential scanning fluorimetry (DSF) and tryptophan fluorescence revealed that most mutations caused protein instability and aggregation. The mutation A463K, equivalent to N558K in human SLC26A4, which is located within α-helix 1 of the DauA STAS domain, stabilized the protein. CD measurements showed that most disease-related mutants had a mildly reduced helix content, but were more sensitive to thermal denaturation. Fluorescence spectroscopy showed that the mutants had more open structures and were more readily denatured by urea, whereas DSF indicated more labile folds. Overall, we conclude that the disease-associated mutations destabilized the STAS domain resulting in an increased propensity to misfold and aggregate.
Collapse
|
100
|
Liu Y, Yang J, Chen LM. Structure and Function of SLC4 Family [Formula: see text] Transporters. Front Physiol 2015; 6:355. [PMID: 26648873 PMCID: PMC4664831 DOI: 10.3389/fphys.2015.00355] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 11/10/2015] [Indexed: 12/12/2022] Open
Abstract
The solute carrier SLC4 family consists of 10 members, nine of which are [Formula: see text] transporters, including three Na(+)-independent Cl(-)/[Formula: see text] exchangers AE1, AE2, and AE3, five Na(+)-coupled [Formula: see text] transporters NBCe1, NBCe2, NBCn1, NBCn2, and NDCBE, as well as "AE4" whose Na(+)-dependence remains controversial. The SLC4 [Formula: see text] transporters play critical roles in pH regulation and transepithelial movement of electrolytes with a broad range of demonstrated physiological relevances. Dysfunctions of these transporters are associated with a series of human diseases. During the past decades, tremendous amount of effort has been undertaken to investigate the topological organization of the SLC4 transporters in the plasma membrane. Based upon the proposed topology models, mutational and functional studies have identified important structural elements likely involved in the ion translocation by the SLC4 transporters. In the present article, we review the advances during the past decades in understanding the structure and function of the SLC4 transporters.
Collapse
Affiliation(s)
- Ying Liu
- Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Biophysics and Molecular Physiology, School of Life Science and Technology, Huazhong University of Science and TechnologyWuhan, China
| | - Jichun Yang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science CenterBeijing, China
| | - Li-Ming Chen
- Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Biophysics and Molecular Physiology, School of Life Science and Technology, Huazhong University of Science and TechnologyWuhan, China
| |
Collapse
|