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Novero AG, Rodríguez PT, De la Vega Beltrán JL, Schiavi-Ehrenhaus LJ, Luque GM, Carruba M, Stival C, Gentile I, Ritagliati C, Santi CM, Nishigaki T, Krapf D, Buffone MG, Darszon A, Treviño CL, Krapf D. The sodium-proton exchangers sNHE and NHE1 control plasma membrane hyperpolarization in mouse sperm. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.04.583310. [PMID: 38496535 PMCID: PMC10942401 DOI: 10.1101/2024.03.04.583310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Sperm capacitation, crucial for fertilization, occurs in the female reproductive tract and can be replicated in vitro using a medium rich in bicarbonate, calcium, and albumin. These components trigger the cAMP-PKA signaling cascade, proposed to promote hyperpolarization of the mouse sperm plasma membrane through activation of SLO3 K+ channel. Hyperpolarization is a hallmark of capacitation: proper membrane hyperpolarization renders higher in vitro fertilizing ability, while Slo3 KO mice are infertile. However, the precise regulation of SLO3 opening remains elusive. Our study challenges the involvement of PKA in this event and reveals the role of Na+/H+ exchangers. During capacitation, calcium increase through CatSper channels activates NHE1, while cAMP directly stimulates the sperm-specific NHE, collectively promoting the alkalinization threshold needed for SLO3 opening. Hyperpolarization then feeds back Na+/H+ activity. Our work is supported by pharmacology, and a plethora of KO mouse models, and proposes a novel pathway leading to hyperpolarization.
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Affiliation(s)
- Analia G Novero
- Instituto de Biología Molecular y Celular de Rosario, CONICET-UNR, and Laboratorio de Medicina Reproductiva, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Rosario SF2000, Argentina
| | | | | | - Liz J Schiavi-Ehrenhaus
- Instituto de Bíologia y Medicina Experimental (IBYME-CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Guillermina M Luque
- Instituto de Bíologia y Medicina Experimental (IBYME-CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Micaela Carruba
- Instituto de Biología Molecular y Celular de Rosario, CONICET-UNR, and Laboratorio de Medicina Reproductiva, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Rosario SF2000, Argentina
| | - Cintia Stival
- Instituto de Biología Molecular y Celular de Rosario, CONICET-UNR, and Laboratorio de Medicina Reproductiva, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Rosario SF2000, Argentina
| | - Iñaki Gentile
- Instituto de Biología Molecular y Celular de Rosario, CONICET-UNR, and Laboratorio de Medicina Reproductiva, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Rosario SF2000, Argentina
| | - Carla Ritagliati
- Instituto de Biología Molecular y Celular de Rosario, CONICET-UNR, and Laboratorio de Medicina Reproductiva, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Rosario SF2000, Argentina
| | - Celia M Santi
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis Missouri 63110, USA
| | | | - Diego Krapf
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, CO 80526, USA
| | - Mariano G Buffone
- Instituto de Bíologia y Medicina Experimental (IBYME-CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | | | | | - Dario Krapf
- Instituto de Biología Molecular y Celular de Rosario, CONICET-UNR, and Laboratorio de Medicina Reproductiva, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Rosario SF2000, Argentina
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2
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Zimmermannová O, Velázquez D, Papoušková K, Průša V, Radová V, Falson P, Sychrová H. The Hydrophilic C-terminus of Yeast Plasma-membrane Na +/H + Antiporters Impacts Their Ability to Transport K . J Mol Biol 2024; 436:168443. [PMID: 38211892 DOI: 10.1016/j.jmb.2024.168443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/18/2023] [Accepted: 01/06/2024] [Indexed: 01/13/2024]
Abstract
Yeast plasma-membrane Na+/H+ antiporters (Nha/Sod) ensure the optimal intracellular level of alkali-metal cations and protons in cells. They are predicted to consist of 13 transmembrane segments (TMSs) and a large hydrophilic C-terminal cytoplasmic part with seven conserved domains. The substrate specificity, specifically the ability to recognize and transport K+ cations in addition to Na+ and Li+, differs among homologs. In this work, we reveal that the composition of the C-terminus impacts the ability of antiporters to transport particular cations. In the osmotolerant yeast Zygosaccharomyces rouxii, the Sod2-22 antiporter only efficiently exports Na+ and Li+, but not K+. The introduction of a negative charge or removal of a positive charge in one of the C-terminal conserved regions (C3) enabled ZrSod2-22 to transport K+. The same mutations rescued the low level of activity and purely Li+ specificity of ZrSod2-22 with the A179T mutation in TMS6, suggesting a possible interaction between this TMS and the C-terminus. The truncation or replacement of the C-terminal part of ZrSod2-22 with the C-terminus of a K+-transporting Nha/Sod antiporter (Saccharomyces cerevisiae Nha1 or Z. rouxii Nha1) also resulted in an antiporter with the capacity to export K+. In addition, in ScNha1, the replacement of three positively charged arginine residues 539-541 in the C3 region with alanine caused its inability to provide cells with tolerance to Li+. All our results demonstrate that the physiological functions of yeast Nha/Sod antiporters, either in salt tolerance or in K+ homeostasis, depend on the composition of their C-terminal parts.
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Affiliation(s)
- Olga Zimmermannová
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
| | - Diego Velázquez
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
| | - Klára Papoušková
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
| | - Vojtěch Průša
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
| | - Viktorie Radová
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
| | - Pierre Falson
- Drug Resistance Membrane Proteins Group, National Centre for Scientific Research and Lyon I University Laboratory n°5086, Institute of Biology and Chemistry of Proteins, Lyon, France.
| | - Hana Sychrová
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
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3
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Yeo H, Mehta V, Gulati A, Drew D. Structure and electromechanical coupling of a voltage-gated Na +/H + exchanger. Nature 2023; 623:193-201. [PMID: 37880360 PMCID: PMC10620092 DOI: 10.1038/s41586-023-06518-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 08/04/2023] [Indexed: 10/27/2023]
Abstract
Voltage-sensing domains control the activation of voltage-gated ion channels, with a few exceptions1. One such exception is the sperm-specific Na+/H+ exchanger SLC9C1, which is the only known transporter to be regulated by voltage-sensing domains2-5. After hyperpolarization of sperm flagella, SLC9C1 becomes active, causing pH alkalinization and CatSper Ca2+ channel activation, which drives chemotaxis2,6. SLC9C1 activation is further regulated by cAMP2,7, which is produced by soluble adenyl cyclase (sAC). SLC9C1 is therefore an essential component of the pH-sAC-cAMP signalling pathway in metazoa8,9, required for sperm motility and fertilization4. Despite its importance, the molecular basis of SLC9C1 voltage activation is unclear. Here we report cryo-electron microscopy (cryo-EM) structures of sea urchin SLC9C1 in detergent and nanodiscs. We show that the voltage-sensing domains are positioned in an unusual configuration, sandwiching each side of the SLC9C1 homodimer. The S4 segment is very long, 90 Å in length, and connects the voltage-sensing domains to the cytoplasmic cyclic-nucleotide-binding domains. The S4 segment is in the up configuration-the inactive state of SLC9C1. Consistently, although a negatively charged cavity is accessible for Na+ to bind to the ion-transporting domains of SLC9C1, an intracellular helix connected to S4 restricts their movement. On the basis of the differences in the cryo-EM structure of SLC9C1 in the presence of cAMP, we propose that, upon hyperpolarization, the S4 segment moves down, removing this constriction and enabling Na+/H+ exchange.
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Affiliation(s)
- Hyunku Yeo
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Ved Mehta
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Ashutosh Gulati
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - David Drew
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm, Sweden.
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4
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Digging into the 3D Structure Predictions of AlphaFold2 with Low Confidence: Disorder and Beyond. Biomolecules 2022; 12:biom12101467. [PMID: 36291675 PMCID: PMC9599455 DOI: 10.3390/biom12101467] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/04/2022] [Accepted: 10/05/2022] [Indexed: 01/12/2023] Open
Abstract
AlphaFold2 (AF2) has created a breakthrough in biology by providing three-dimensional structure models for whole-proteome sequences, with unprecedented levels of accuracy. In addition, the AF2 pLDDT score, related to the model confidence, has been shown to provide a good measure of residue-wise disorder. Here, we combined AF2 predictions with pyHCA, a tool we previously developed to identify foldable segments and estimate their order/disorder ratio, from a single protein sequence. We focused our analysis on the AF2 predictions available for 21 reference proteomes (AFDB v1), in particular on their long foldable segments (>30 amino acids) that exhibit characteristics of soluble domains, as estimated by pyHCA. Among these segments, we provided a global analysis of those with very low pLDDT values along their entire length and compared their characteristics to those of segments with very high pLDDT values. We highlighted cases containing conditional order, as well as cases that could form well-folded structures but escape the AF2 prediction due to a shallow multiple sequence alignment and/or undocumented structure or fold. AF2 and pyHCA can therefore be advantageously combined to unravel cryptic structural features in whole proteomes and to refine predictions for different flavors of disorder.
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Newcombe EA, Fernandes CB, Lundsgaard JE, Brakti I, Lindorff-Larsen K, Langkilde AE, Skriver K, Kragelund BB. Insight into Calcium-Binding Motifs of Intrinsically Disordered Proteins. Biomolecules 2021; 11:1173. [PMID: 34439840 PMCID: PMC8391695 DOI: 10.3390/biom11081173] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 07/31/2021] [Accepted: 08/06/2021] [Indexed: 01/28/2023] Open
Abstract
Motifs within proteins help us categorize their functions. Intrinsically disordered proteins (IDPs) are rich in short linear motifs, conferring them many different roles. IDPs are also frequently highly charged and, therefore, likely to interact with ions. Canonical calcium-binding motifs, such as the EF-hand, often rely on the formation of stabilizing flanking helices, which are a key characteristic of folded proteins, but are absent in IDPs. In this study, we probe the existence of a calcium-binding motif relevant to IDPs. Upon screening several carefully selected IDPs using NMR spectroscopy supplemented with affinity quantification by colorimetric assays, we found calcium-binding motifs in IDPs which could be categorized into at least two groups-an Excalibur-like motif, sequentially similar to the EF-hand loop, and a condensed-charge motif carrying repetitive negative charges. The motifs show an affinity for calcium typically in the ~100 μM range relevant to regulatory functions and, while calcium binding to the condensed-charge motif had little effect on the overall compaction of the IDP chain, calcium binding to Excalibur-like motifs resulted in changes in compaction. Thus, calcium binding to IDPs may serve various structural and functional roles that have previously been underreported.
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Affiliation(s)
- Estella A. Newcombe
- Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, 2200 Copenhagen, Denmark; (E.A.N.); (C.B.F.); (J.E.L.); (I.B.); (K.L.-L.); (K.S.)
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark;
| | - Catarina B. Fernandes
- Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, 2200 Copenhagen, Denmark; (E.A.N.); (C.B.F.); (J.E.L.); (I.B.); (K.L.-L.); (K.S.)
- REPIN, Department of Biology, University of Copenhagen, Ole Maaloes Vej 5, 2200 Copenhagen, Denmark
| | - Jeppe E. Lundsgaard
- Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, 2200 Copenhagen, Denmark; (E.A.N.); (C.B.F.); (J.E.L.); (I.B.); (K.L.-L.); (K.S.)
- REPIN, Department of Biology, University of Copenhagen, Ole Maaloes Vej 5, 2200 Copenhagen, Denmark
| | - Inna Brakti
- Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, 2200 Copenhagen, Denmark; (E.A.N.); (C.B.F.); (J.E.L.); (I.B.); (K.L.-L.); (K.S.)
- REPIN, Department of Biology, University of Copenhagen, Ole Maaloes Vej 5, 2200 Copenhagen, Denmark
| | - Kresten Lindorff-Larsen
- Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, 2200 Copenhagen, Denmark; (E.A.N.); (C.B.F.); (J.E.L.); (I.B.); (K.L.-L.); (K.S.)
| | - Annette E. Langkilde
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark;
| | - Karen Skriver
- Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, 2200 Copenhagen, Denmark; (E.A.N.); (C.B.F.); (J.E.L.); (I.B.); (K.L.-L.); (K.S.)
- REPIN, Department of Biology, University of Copenhagen, Ole Maaloes Vej 5, 2200 Copenhagen, Denmark
| | - Birthe B. Kragelund
- Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, 2200 Copenhagen, Denmark; (E.A.N.); (C.B.F.); (J.E.L.); (I.B.); (K.L.-L.); (K.S.)
- REPIN, Department of Biology, University of Copenhagen, Ole Maaloes Vej 5, 2200 Copenhagen, Denmark
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6
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Blawn KT, Kellohen KL, Galloway EA, Wahl J, Vivek A, Verkhovsky VG, Barker NK, Cottier KE, Vallecillo TG, Langlais PR, Liktor-Busa E, Vanderah TW, Largent-Milnes TM. Sex hormones regulate NHE1 functional expression and brain endothelial proteome to control paracellular integrity of the blood endothelial barrier. Brain Res 2021; 1763:147448. [PMID: 33771519 PMCID: PMC10494867 DOI: 10.1016/j.brainres.2021.147448] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 03/18/2021] [Accepted: 03/19/2021] [Indexed: 01/31/2023]
Abstract
BACKGROUND Sex hormones have been implicated in pH regulation of numerous physiological systems. One consistent factor of these studies is the sodium-hydrogen exchanger 1 (NHE1). NHE1 has been associated with pH homeostasis at epithelial barriers. Hormone fluctuations have been implicated in protection and risk for breaches in blood brain barrier (BBB)/blood endothelial barrier (BEB) integrity. Few studies, however, have investigated BBB/BEB integrity in neurological disorders in the context of sex-hormone regulation of pH homeostasis. METHODS//RESULTS Physiologically relevant concentrations of 17-β-estradiol (E2, 294 pM), progesterone (P, 100 nM), and testosterone (T,3.12 nM) were independently applied to cultured immortalized bEnd.3 brain endothelial cells to study the BEB. Individual gonadal hormones showed preferential effects on extracellular pH (E2), 14C-sucrose uptake (T), stimulated paracellular breaches (P) with dependence on functional NHE1 expression without impacting transendothelial resistance (TEER) or total protein expression. While total NHE1 expression was not changed as determined via whole cell lysate and subcellular fractionation experiment, biotinylation of NHE1 for surface membrane expression showed E2 reduced functional expression. Quantitative proteomic analysis revealed divergent effects of 17-β-estradiol and testosterone on changes in protein abundance in bEnd.3 endothelial cells as compared to untreated controls. CONCLUSIONS These data suggest that circulating levels of sex hormones may independently control BEB integrity by 1) regulating pH homeostasis through NHE1 functional expression and 2) modifying the endothelial proteome.
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Affiliation(s)
- Kiera T Blawn
- University of Arizona, Department of Pharmacology, Tucson, AZ, USA
| | | | - Emily A Galloway
- University of Arizona, Department of Pharmacology, Tucson, AZ, USA
| | - Jared Wahl
- University of Arizona, Department of Pharmacology, Tucson, AZ, USA
| | - Anjali Vivek
- University of Arizona, Department of Pharmacology, Tucson, AZ, USA
| | | | - Natalie K Barker
- University of Arizona, Department of Medicine, Division of Endocrinology, College of Medicine, Tucson, AZ, USA
| | | | | | - Paul R Langlais
- University of Arizona, Department of Medicine, Division of Endocrinology, College of Medicine, Tucson, AZ, USA
| | | | - Todd W Vanderah
- University of Arizona, Department of Pharmacology, Tucson, AZ, USA
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7
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Olamoyesan A, Ang D, Rodger A. Circular dichroism for secondary structure determination of proteins with unfolded domains using a self-organising map algorithm SOMSpec. RSC Adv 2021; 11:23985-23991. [PMID: 35479026 PMCID: PMC9036635 DOI: 10.1039/d1ra02898g] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 06/27/2021] [Indexed: 01/03/2023] Open
Abstract
Many proteins and peptides are increasingly being recognised to contain unfolded domains or populations that are key to their function, whether it is in ligand binding or material assembly. We report an approach to determine the secondary structure for proteins with suspected significant unfolded domains or populations using our neural network approach SOMSpec. We proceed by derandomizing spectra by removing fractions of random coil (RC) spectra prior to secondary structure fitting and then regenerating α-helical and β-sheet contents for the experimental proteins. Application to bovine serum albumin spectra as a function of temperature proved to be straightforward, whereas lysozyme and insulin have hidden challenges. The importance of being able to interrogate the SOMSpec output to understand the best matching units used in the predictions is illustrated with lysozyme and insulin whose partially melted proteins proved to have significant βII content and their CD spectrum looks the same as that for a random coil.
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Affiliation(s)
- Adewale Olamoyesan
- Department of Molecular Sciences, Macquarie University NSW 2109 Australia
| | - Dale Ang
- Department of Molecular Sciences, Macquarie University NSW 2109 Australia
| | - Alison Rodger
- Department of Molecular Sciences, Macquarie University NSW 2109 Australia
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8
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Sjøgaard-Frich LM, Prestel A, Pedersen ES, Severin M, Kristensen KK, Olsen JG, Kragelund BB, Pedersen SF. Dynamic Na +/H + exchanger 1 (NHE1) - calmodulin complexes of varying stoichiometry and structure regulate Ca 2+-dependent NHE1 activation. eLife 2021; 10:60889. [PMID: 33655882 PMCID: PMC8009664 DOI: 10.7554/elife.60889] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 03/01/2021] [Indexed: 11/25/2022] Open
Abstract
Calmodulin (CaM) engages in Ca2+-dependent interactions with numerous proteins, including a still incompletely understood physical and functional interaction with the human Na+/H+-exchanger NHE1. Using nuclear magnetic resonance (NMR) spectroscopy, isothermal titration calorimetry, and fibroblasts stably expressing wildtype and mutant NHE1, we discovered multiple accessible states of this functionally important complex existing in different NHE1:CaM stoichiometries and structures. We determined the NMR solution structure of a ternary complex in which CaM links two NHE1 cytosolic tails. In vitro, stoichiometries and affinities could be tuned by variations in NHE1:CaM ratio and calcium ([Ca2+]) and by phosphorylation of S648 in the first CaM-binding α-helix. In cells, Ca2+-CaM-induced NHE1 activity was reduced by mimicking S648 phosphorylation and by mutation of the first CaM-binding α-helix, whereas it was unaffected by inhibition of Akt, one of several kinases phosphorylating S648. Our results demonstrate a diversity of NHE1:CaM interaction modes and suggest that CaM may contribute to NHE1 dimerization and thereby augment NHE1 regulation. We propose that a similar structural diversity is of relevance to many other CaM complexes.
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Affiliation(s)
- Lise M Sjøgaard-Frich
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Andreas Prestel
- Structural Biology and NMR Laboratory, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Emilie S Pedersen
- Structural Biology and NMR Laboratory, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Marc Severin
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Kristian Kølby Kristensen
- Finsen Laboratory, Rigshospitalet, Copenhagen, Denmark.,Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | - Johan G Olsen
- Structural Biology and NMR Laboratory, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Birthe B Kragelund
- Structural Biology and NMR Laboratory, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Stine Falsig Pedersen
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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9
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Abstract
Extracellular acidification is a well-known driver of tumorigenesis that has been extensively studied. In contrast, the role of endosomal pH is novel and relatively unexplored. There is emerging evidence from a growing number of studies showing that the pH of endosomal compartments controls proliferation, migration, stemness, and sensitivity to chemoradiation therapy in a variety of tumors. Endosomes are a crucial hub, mediating cellular communication with the external environment. By finely regulating the sorting and trafficking of vesicular cargo for degradation or recycling, endosomal pH determines the fate of plasma membrane proteins, lipids, and extracellular signals including growth factor receptors and their ligands. Several critical regulators of endosomal pH have been identified, including multiple isoforms of the family of electroneutral Na+/H+ exchangers (NHE) such as NHE6 and NHE9. Recent studies have shed light on molecular mechanisms linking endosomal pH to cancer malignancy. Manipulating endosomal pH by epigenetic reprogramming, small molecules, or nanoparticles may offer promising new options in cancer therapy. In this review, we summarize evidence linking endosomal pH to cancer, with a focus on the role of endosomal Na+/H+ exchangers and how they affect the prognosis of cancer patients, and also suggest how regulation of endosomal pH may be exploited to develop new cancer therapies.
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10
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Winklemann I, Matsuoka R, Meier PF, Shutin D, Zhang C, Orellana L, Sexton R, Landreh M, Robinson CV, Beckstein O, Drew D. Structure and elevator mechanism of the mammalian sodium/proton exchanger NHE9. EMBO J 2020; 39:e105908. [PMID: 33118634 PMCID: PMC7737618 DOI: 10.15252/embj.2020105908] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 09/09/2020] [Accepted: 09/10/2020] [Indexed: 12/21/2022] Open
Abstract
Na+ /H+ exchangers (NHEs) are ancient membrane-bound nanomachines that work to regulate intracellular pH, sodium levels and cell volume. NHE activities contribute to the control of the cell cycle, cell proliferation, cell migration and vesicle trafficking. NHE dysfunction has been linked to many diseases, and they are targets of pharmaceutical drugs. Despite their fundamental importance to cell homeostasis and human physiology, structural information for the mammalian NHE was lacking. Here, we report the cryogenic electron microscopy structure of NHE isoform 9 (SLC9A9) from Equus caballus at 3.2 Å resolution, an endosomal isoform highly expressed in the brain and associated with autism spectrum (ASD) and attention deficit hyperactivity (ADHD) disorders. Despite low sequence identity, the NHE9 architecture and ion-binding site are remarkably similar to distantly related bacterial Na+ /H+ antiporters with 13 transmembrane segments. Collectively, we reveal the conserved architecture of the NHE ion-binding site, their elevator-like structural transitions, the functional implications of autism disease mutations and the role of phosphoinositide lipids to promote homodimerization that, together, have important physiological ramifications.
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Affiliation(s)
- Iven Winklemann
- Department of Biochemistry and BiophysicsStockholm UniversityStockholmSweden
| | - Rei Matsuoka
- Department of Biochemistry and BiophysicsStockholm UniversityStockholmSweden
| | - Pascal F Meier
- Department of Biochemistry and BiophysicsStockholm UniversityStockholmSweden
| | - Denis Shutin
- Department of ChemistryUniversity of OxfordOxfordUK
| | - Chenou Zhang
- Department of PhysicsCenter for Biological PhysicsArizona State UniversityTempeAZUSA
| | - Laura Orellana
- Department of Biochemistry and BiophysicsStockholm UniversityStockholmSweden
| | - Ricky Sexton
- Department of PhysicsCenter for Biological PhysicsArizona State UniversityTempeAZUSA
| | - Michael Landreh
- Department of Microbiology, Tumor and Cell BiologyKarolinska InstituteStockholmSweden
| | | | - Oliver Beckstein
- Department of PhysicsCenter for Biological PhysicsArizona State UniversityTempeAZUSA
| | - David Drew
- Department of Biochemistry and BiophysicsStockholm UniversityStockholmSweden
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11
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Hendus-Altenburger R, Vogensen J, Pedersen ES, Luchini A, Araya-Secchi R, Bendsoe AH, Prasad NS, Prestel A, Cardenas M, Pedraz-Cuesta E, Arleth L, Pedersen SF, Kragelund BB. The intracellular lipid-binding domain of human Na +/H + exchanger 1 forms a lipid-protein co-structure essential for activity. Commun Biol 2020; 3:731. [PMID: 33273619 PMCID: PMC7713384 DOI: 10.1038/s42003-020-01455-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 11/03/2020] [Indexed: 12/03/2022] Open
Abstract
Dynamic interactions of proteins with lipid membranes are essential regulatory events in biology, but remain rudimentarily understood and particularly overlooked in membrane proteins. The ubiquitously expressed membrane protein Na+/H+-exchanger 1 (NHE1) regulates intracellular pH (pHi) with dysregulation linked to e.g. cancer and cardiovascular diseases. NHE1 has a long, regulatory cytosolic domain carrying a membrane-proximal region described as a lipid-interacting domain (LID), yet, the LID structure and underlying molecular mechanisms are unknown. Here we decompose these, combining structural and biophysical methods, molecular dynamics simulations, cellular biotinylation- and immunofluorescence analysis and exchanger activity assays. We find that the NHE1-LID is intrinsically disordered and, in presence of membrane mimetics, forms a helical αα-hairpin co-structure with the membrane, anchoring the regulatory domain vis-a-vis the transport domain. This co-structure is fundamental for NHE1 activity, as its disintegration reduced steady-state pHi and the rate of pHi recovery after acid loading. We propose that regulatory lipid-protein co-structures may play equally important roles in other membrane proteins.
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Affiliation(s)
- Ruth Hendus-Altenburger
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200, Copenhagen N, Denmark
- Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100, Copenhagen Ø, Denmark
| | - Jens Vogensen
- Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100, Copenhagen Ø, Denmark
| | - Emilie Skotte Pedersen
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200, Copenhagen N, Denmark
| | - Alessandra Luchini
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen Ø, Denmark
| | - Raul Araya-Secchi
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen Ø, Denmark
| | - Anne H Bendsoe
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200, Copenhagen N, Denmark
- Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100, Copenhagen Ø, Denmark
| | - Nanditha Shyam Prasad
- Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100, Copenhagen Ø, Denmark
| | - Andreas Prestel
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200, Copenhagen N, Denmark
| | - Marité Cardenas
- Biofilms Research Center for Biointerfaces, Malmö University, Per Albin Hanssons Väg 35, 214 32, Malmö, Sweden
| | - Elena Pedraz-Cuesta
- Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100, Copenhagen Ø, Denmark
| | - Lise Arleth
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen Ø, Denmark.
| | - Stine F Pedersen
- Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100, Copenhagen Ø, Denmark.
| | - Birthe B Kragelund
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200, Copenhagen N, Denmark.
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Role of Genetic Mutations of the Na +/H + Exchanger Isoform 1, in Human Disease and Protein Targeting and Activity. Mol Cell Biochem 2020; 476:1221-1232. [PMID: 33201382 DOI: 10.1007/s11010-020-03984-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 11/06/2020] [Indexed: 01/22/2023]
Abstract
The mammalian Na+/H+ exchanger isoform one (NHE1) is a plasma membrane protein that is ubiquitously present in human cells. It functions to regulate intracellular pH removing an intracellular proton in exchange for one extracellular sodium and is involved in heart disease and in promoting metastasis in cancer. It is made of a 500 amino acid membrane domain plus a 315 amino acid, regulatory cytosolic tail. The membrane domain is thought to have 12 transmembrane segments and a large membrane-associated extracellular loop. Early studies demonstrated that in mice, disruption of the NHE1 gene results in locomotor ataxia and a phenotype of slow-wave epilepsy. Defects included a progressive neuronal degeneration. Growth and reproductive ability were also reduced. Recent studies have identified human autosomal homozygous recessive mutations in the NHE1 gene (SLC9A1) that result in impaired development, ataxia and other severe defects, and explain the cause of the human disease Lichtenstein-Knorr syndrome. Other human mutations have been identified that are stop codon polymorphisms. These cause short non-functional NHE1 proteins, while other genetic polymorphisms in the NHE1 gene cause impaired expression of the NHE1 protein, reduced activity, enhanced protein degradation or altered kinetic activation of the protein. Since NHE1 plays a key role in many human physiological functions and in human disease, genetic polymorphisms of the protein that significantly alter its function and are likely play significant roles in varying human phenotypes and be involved in disease.
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Papouskova K, Moravcova M, Masrati G, Ben-Tal N, Sychrova H, Zimmermannova O. C5 conserved region of hydrophilic C-terminal part of Saccharomyces cerevisiae Nha1 antiporter determines its requirement of Erv14 COPII cargo receptor for plasma-membrane targeting. Mol Microbiol 2020; 115:41-57. [PMID: 32864748 DOI: 10.1111/mmi.14595] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/23/2020] [Accepted: 08/22/2020] [Indexed: 01/03/2023]
Abstract
Erv14, a conserved cargo receptor of COPII vesicles, helps the proper trafficking of many but not all transporters to the yeast plasma membrane, for example, three out of five alkali-metal-cation transporters in Saccharomyces cerevisiae. Among them, the Nha1 cation/proton antiporter, which participates in cell cation and pH homeostasis, is a large membrane protein (985 aa) possessing a long hydrophilic C-terminus (552 aa) containing six conserved regions (C1-C6) with unknown function. A short Nha1 version, lacking almost the entire C-terminus, still binds to Erv14 but does not need it to be targeted to the plasma membrane. Comparing the localization and function of ScNha1 variants shortened at its C-terminus in cells with or without Erv14 reveals that only ScNha1 versions possessing the complete C5 region are dependent on Erv14. In addition, our broad evolutionary conservation analysis of fungal Na+ /H+ antiporters identified new conserved regions in their C-termini, and our experiments newly show C5 and other, so far unknown, regions of the C-terminus, to be involved in the functionality and substrate specificity of ScNha1. Taken together, our results reveal that also relatively small hydrophilic parts of some yeast membrane proteins underlie their need to interact with the Erv14 cargo receptor.
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Affiliation(s)
- Klara Papouskova
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic
| | - Michaela Moravcova
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic
| | - Gal Masrati
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Nir Ben-Tal
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Hana Sychrova
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic
| | - Olga Zimmermannova
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic
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Bugge K, Brakti I, Fernandes CB, Dreier JE, Lundsgaard JE, Olsen JG, Skriver K, Kragelund BB. Interactions by Disorder - A Matter of Context. Front Mol Biosci 2020; 7:110. [PMID: 32613009 PMCID: PMC7308724 DOI: 10.3389/fmolb.2020.00110] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 05/11/2020] [Indexed: 12/15/2022] Open
Abstract
Living organisms depend on timely and organized interactions between proteins linked in interactomes of high complexity. The recent increased precision by which protein interactions can be studied, and the enclosure of intrinsic structural disorder, suggest that it is time to zoom out and embrace protein interactions beyond the most central points of physical encounter. The present paper discusses protein-protein interactions in the view of structural disorder with an emphasis on flanking regions and contexts of disorder-based interactions. Context constitutes an overarching concept being of physicochemical, biomolecular, and physiological nature, but it also includes the immediate molecular context of the interaction. For intrinsically disordered proteins, which often function by exploiting short linear motifs, context contributes in highly regulatory and decisive manners and constitute a yet largely unrecognized source of interaction potential in a multitude of biological processes. Through selected examples, this review emphasizes how multivalency, charges and charge clusters, hydrophobic patches, dynamics, energetic frustration, and ensemble redistribution of flanking regions or disordered contexts are emerging as important contributors to allosteric regulation, positive and negative cooperativity, feedback regulation and negative selection in binding. The review emphasizes that understanding context, and in particular the role the molecular disordered context and flanking regions take on in protein interactions, constitute an untapped well of energetic modulation potential, also of relevance to drug discovery and development.
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Affiliation(s)
- Katrine Bugge
- REPIN, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Inna Brakti
- REPIN, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Catarina B. Fernandes
- REPIN, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Jesper E. Dreier
- REPIN, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Jeppe E. Lundsgaard
- REPIN, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Johan G. Olsen
- REPIN, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Karen Skriver
- REPIN, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Birthe B. Kragelund
- REPIN, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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15
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Protocol for Investigating the Interactions Between Intrinsically Disordered Proteins and Membranes by Neutron Reflectometry. Methods Mol Biol 2020; 2141:569-584. [PMID: 32696378 DOI: 10.1007/978-1-0716-0524-0_29] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Several intrinsically disordered proteins (IDPs) exhibit high affinity for lipid membranes. Among the different biophysical methods to probe protein-lipid interaction, neutron reflectometry (NR) can provide direct and structural detailed information on the location of the IDP with respect to the membrane. Supported lipid bilayers are commonly used as cell membrane models in such experiments. NR measurements can be collected on the supported lipid bilayer before and after the interaction with the IDP to characterize whether the protein molecules are mainly located on the membrane surface (interaction with the lipid headgroups), are penetrating into the hydrophobic region of the membrane (interaction with the lipid acyl chains), or are not interacting at all with the membrane. The lipid composition of the supported lipid bilayer can easily be tuned; hence the NR experiments can be designed to investigate selective IDP-lipid interactions.This chapter will describe the fundamental steps for performing an NR experiment and the subsequent data analysis aimed at characterizing IDP-lipid bilayer interactions. The specific case of an intrinsically disordered region (IDR) from the membrane protein Na+/H+ exchanger isoform 1 (NHE1) will be used as an example, but the same protocol can be easily adapted to other IDPs.
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16
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The activity of Saccharomyces cerevisiae Na+, K+/H+ antiporter Nha1 is negatively regulated by 14-3-3 protein binding at serine 481. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:118534. [DOI: 10.1016/j.bbamcr.2019.118534] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 08/02/2019] [Accepted: 08/16/2019] [Indexed: 12/25/2022]
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17
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Pedersen SF, Counillon L. The SLC9A-C Mammalian Na +/H + Exchanger Family: Molecules, Mechanisms, and Physiology. Physiol Rev 2019; 99:2015-2113. [PMID: 31507243 DOI: 10.1152/physrev.00028.2018] [Citation(s) in RCA: 103] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Na+/H+ exchangers play pivotal roles in the control of cell and tissue pH by mediating the electroneutral exchange of Na+ and H+ across cellular membranes. They belong to an ancient family of highly evolutionarily conserved proteins, and they play essential physiological roles in all phyla. In this review, we focus on the mammalian Na+/H+ exchangers (NHEs), the solute carrier (SLC) 9 family. This family of electroneutral transporters constitutes three branches: SLC9A, -B, and -C. Within these, each isoform exhibits distinct tissue expression profiles, regulation, and physiological roles. Some of these transporters are highly studied, with hundreds of original articles, and some are still only rudimentarily understood. In this review, we present and discuss the pioneering original work as well as the current state-of-the-art research on mammalian NHEs. We aim to provide the reader with a comprehensive view of core knowledge and recent insights into each family member, from gene organization over protein structure and regulation to physiological and pathophysiological roles. Particular attention is given to the integrated physiology of NHEs in the main organ systems. We provide several novel analyses and useful overviews, and we pinpoint main remaining enigmas, which we hope will inspire novel research on these highly versatile proteins.
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Affiliation(s)
- S F Pedersen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark; and Université Côte d'Azur, CNRS, Laboratoire de Physiomédecine Moléculaire, LP2M, France, and Laboratories of Excellence Ion Channel Science and Therapeutics, Nice, France
| | - L Counillon
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark; and Université Côte d'Azur, CNRS, Laboratoire de Physiomédecine Moléculaire, LP2M, France, and Laboratories of Excellence Ion Channel Science and Therapeutics, Nice, France
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Molecular basis for the binding and selective dephosphorylation of Na +/H + exchanger 1 by calcineurin. Nat Commun 2019; 10:3489. [PMID: 31375679 PMCID: PMC6677818 DOI: 10.1038/s41467-019-11391-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 07/08/2019] [Indexed: 01/26/2023] Open
Abstract
Very little is known about how Ser/Thr protein phosphatases specifically recruit and dephosphorylate substrates. Here, we identify how the Na+/H+-exchanger 1 (NHE1), a key regulator of cellular pH homeostasis, is regulated by the Ser/Thr phosphatase calcineurin (CN). NHE1 activity is increased by phosphorylation of NHE1 residue T779, which is specifically dephosphorylated by CN. While it is known that Ser/Thr protein phosphatases prefer pThr over pSer, we show that this preference is not key to this exquisite CN selectivity. Rather a combination of molecular mechanisms, including recognition motifs, dynamic charge-charge interactions and a substrate interaction pocket lead to selective dephosphorylation of pT779. Our data identify T779 as a site regulating NHE1-mediated cellular acid extrusion and provides a molecular understanding of NHE1 substrate selection by CN, specifically, and how phosphatases recruit specific substrates, generally.
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Functional Analysis of Human Hub Proteins and Their Interactors Involved in the Intrinsic Disorder-Enriched Interactions. Int J Mol Sci 2017; 18:ijms18122761. [PMID: 29257115 PMCID: PMC5751360 DOI: 10.3390/ijms18122761] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 12/13/2017] [Accepted: 12/15/2017] [Indexed: 12/15/2022] Open
Abstract
Some of the intrinsically disordered proteins and protein regions are promiscuous interactors that are involved in one-to-many and many-to-one binding. Several studies have analyzed enrichment of intrinsic disorder among the promiscuous hub proteins. We extended these works by providing a detailed functional characterization of the disorder-enriched hub protein-protein interactions (PPIs), including both hubs and their interactors, and by analyzing their enrichment among disease-associated proteins. We focused on the human interactome, given its high degree of completeness and relevance to the analysis of the disease-linked proteins. We quantified and investigated numerous functional and structural characteristics of the disorder-enriched hub PPIs, including protein binding, structural stability, evolutionary conservation, several categories of functional sites, and presence of over twenty types of posttranslational modifications (PTMs). We showed that the disorder-enriched hub PPIs have a significantly enlarged number of disordered protein binding regions and long intrinsically disordered regions. They also include high numbers of targeting, catalytic, and many types of PTM sites. We empirically demonstrated that these hub PPIs are significantly enriched among 11 out of 18 considered classes of human diseases that are associated with at least 100 human proteins. Finally, we also illustrated how over a dozen specific human hubs utilize intrinsic disorder for their promiscuous PPIs.
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Uversky VN. The roles of intrinsic disorder-based liquid-liquid phase transitions in the "Dr. Jekyll-Mr. Hyde" behavior of proteins involved in amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Autophagy 2017; 13:2115-2162. [PMID: 28980860 DOI: 10.1080/15548627.2017.1384889] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Pathological developments leading to amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are associated with misbehavior of several key proteins, such as SOD1 (superoxide dismutase 1), TARDBP/TDP-43, FUS, C9orf72, and dipeptide repeat proteins generated as a result of the translation of the intronic hexanucleotide expansions in the C9orf72 gene, PFN1 (profilin 1), GLE1 (GLE1, RNA export mediator), PURA (purine rich element binding protein A), FLCN (folliculin), RBM45 (RNA binding motif protein 45), SS18L1/CREST, HNRNPA1 (heterogeneous nuclear ribonucleoprotein A1), HNRNPA2B1 (heterogeneous nuclear ribonucleoprotein A2/B1), ATXN2 (ataxin 2), MAPT (microtubule associated protein tau), and TIA1 (TIA1 cytotoxic granule associated RNA binding protein). Although these proteins are structurally and functionally different and have rather different pathological functions, they all possess some levels of intrinsic disorder and are either directly engaged in or are at least related to the physiological liquid-liquid phase transitions (LLPTs) leading to the formation of various proteinaceous membrane-less organelles (PMLOs), both normal and pathological. This review describes the normal and pathological functions of these ALS- and FTLD-related proteins, describes their major structural properties, glances at their intrinsic disorder status, and analyzes the involvement of these proteins in the formation of normal and pathological PMLOs, with the ultimate goal of better understanding the roles of LLPTs and intrinsic disorder in the "Dr. Jekyll-Mr. Hyde" behavior of those proteins.
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Affiliation(s)
- Vladimir N Uversky
- a Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute , Morsani College of Medicine , University of South Florida , Tampa , FL , USA.,b Institute for Biological Instrumentation of the Russian Academy of Sciences , Pushchino, Moscow region , Russia
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21
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Liu Y, Yang M, Cheng H, Sun N, Liu S, Li S, Wang Y, Zheng Y, Uversky VN. The effect of phosphorylation on the salt-tolerance-related functions of the soybean protein PM18, a member of the group-3 LEA protein family. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2017; 1865:1291-1303. [PMID: 28867216 DOI: 10.1016/j.bbapap.2017.08.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 08/08/2017] [Accepted: 08/27/2017] [Indexed: 12/29/2022]
Abstract
Enzymatically driven post-translated modifications (PTMs) usually happen within the intrinsically disordered regions of a target protein and can modulate variety of protein functions. Late embryogenesis abundant (LEA) proteins are a family of the plant intrinsically disordered proteins (IDPs). Despite their important roles in plant stress response, there is currently limited knowledge on the presence and functional and structural effects of phosphorylation on LEA proteins. In this study, we identified three phosphorylation sites (Ser90, Tyr136, and Thr266) in the soybean PM18 protein that belongs to the group-3 LEA proteins. In yeast expression system, PM18 protein increased the salt tolerance of yeast, and the phosphorylation of this protein further enhanced its protective function. Further analysis revealed that Ser90 and Tyr136 are more important than Thr266, and these two sites might work cooperatively in regulating the salt resistance function of PM18. The circular dichroism analysis showed that PM18 protein was disordered in aqueous media, and phosphorylation did not affect the disordered status of this protein. However, phosphorylation promoted formation of more helical structure in the presence of sodium dodecyl sulfate (SDS) or trifluoroethanol (TFE). Furthermore, in dedicated in vitro experiments, phosphorylated PM18 protein was able to better protect lactate dehydrogenase (LDH) from the inactivation induced by the freeze-thaw cycles than its un- or dephosphorylated forms. All these data indicate that phosphorylation may have regulatory effects on the stress-tolerance-related function of LEA proteins. Therefore, further studies are needed to shed more light on functional and structural roles of phosphorylation in LEA proteins.
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Affiliation(s)
- Yun Liu
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong 518060, China.
| | - Meiyan Yang
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Hua Cheng
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Nan Sun
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Simu Liu
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Shuiming Li
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Yong Wang
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Yizhi Zheng
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong 518060, China.
| | - Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd. MDC07, Tampa, FL, USA; Laboratory of New Methods in Biology, Institute for Biological Instrumentation, Russian Academy of Sciences, Institutskaya str., 7, Pushchino, Moscow region 142290, Russia; Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., St. Petersburg 194064, Russia.
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22
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Kjaergaard M, Kragelund BB. Functions of intrinsic disorder in transmembrane proteins. Cell Mol Life Sci 2017; 74:3205-3224. [PMID: 28601983 PMCID: PMC11107515 DOI: 10.1007/s00018-017-2562-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 06/01/2017] [Indexed: 12/19/2022]
Abstract
Intrinsic disorder is common in integral membrane proteins, particularly in the intracellular domains. Despite this observation, these domains are not always recognized as being disordered. In this review, we will discuss the biological functions of intrinsically disordered regions of membrane proteins, and address why the flexibility afforded by disorder is mechanistically important. Intrinsically disordered regions are present in many common classes of membrane proteins including ion channels and transporters; G-protein coupled receptors (GPCRs), receptor tyrosine kinases and cytokine receptors. The functions of the disordered regions are many and varied. We will discuss selected examples including: (1) Organization of receptors, kinases, phosphatases and second messenger sources into signaling complexes. (2) Modulation of the membrane-embedded domain function by ball-and-chain like mechanisms. (3) Trafficking of membrane proteins. (4) Transient membrane associations. (5) Post-translational modifications most notably phosphorylation and (6) disorder-linked isoform dependent function. We finish the review by discussing the future challenges facing the membrane protein community regarding protein disorder.
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Affiliation(s)
- Magnus Kjaergaard
- Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Aarhus, Denmark.
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark.
- The Danish Research Institute of Translational Neuroscience (DANDRITE), Aarhus, Denmark.
| | - Birthe B Kragelund
- Structural Biology and NMR Laboratory and The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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23
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Uversky VN. Intrinsic Disorder, Protein-Protein Interactions, and Disease. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2017; 110:85-121. [PMID: 29413001 DOI: 10.1016/bs.apcsb.2017.06.005] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
It is recognized now that biologically active proteins without stable tertiary structure (known as intrinsically disordered proteins, IDPs) and hybrid proteins containing ordered domains and intrinsically disordered protein regions (IDPRs) are important players found in any given proteome. These IDPs/IDPRs possess functions that complement functional repertoire of their ordered counterparts, being commonly related to recognition, as well as control and regulation of various signaling pathways. They are interaction masters, being able to utilize a wide spectrum of interaction mechanisms, ranging from induced folding to formation of fuzzy complexes where significant levels of disorder are preserved, to polyvalent stochastic interactions playing crucial roles in the liquid-liquid phase transitions leading to the formation of proteinaceous membrane-less organelles. IDPs/IDPRs are tightly controlled themselves via various means, including alternative splicing, precisely controlled expression and degradation, binding to specific partners, and posttranslational modifications. Distortions in the regulation and control of IDPs/IDPRs, as well as their aberrant interactivity are commonly associated with various human diseases. This review presents some aspects of the intrinsic disorder-based functionality and dysfunctionality, paying special attention to the normal and pathological protein-protein interactions.
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Affiliation(s)
- Vladimir N Uversky
- USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, United States; Institute for Biological Instrumentation, Russian Academy of Sciences, Pushchino, Moscow Region, Russia.
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Liu Y, Wu J, Sun N, Tu C, Shi X, Cheng H, Liu S, Li S, Wang Y, Zheng Y, Uversky VN. Intrinsically Disordered Proteins as Important Players during Desiccation Stress of Soybean Radicles. J Proteome Res 2017; 16:2393-2409. [PMID: 28525284 DOI: 10.1021/acs.jproteome.6b01045] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Intrinsically disordered proteins (IDPs) play a variety of important physiological roles in all living organisms. However, there is no comprehensive analysis of the abundance of IDPs associated with environmental stress in plants. Here, we show that a set of heat-stable proteins (i.e., proteins that do not denature after boiling at 100 °C for 10 min) was present in R0mm and R15mm radicles (i.e., before radicle emergence and 15 mm long radicles) of soybean (Glycine max) seeds. This set of 795 iTRAQ-quantified heat-stable proteins contained a high proportion of wholly or highly disordered proteins (15%), which was significantly higher than that estimated for the whole soybean proteome containing 55,787 proteins (9%). The heat-stable proteome of soybean radicles that contain many IDPs could protect lactate dehydrogenase (LDH) during freeze-thaw cycles. Comparison of the 795 heat-stable proteins in the R0mm and R15mm soybean radicles revealed that many of these proteins changed abundance during seedling growth with 170 and 89 proteins being more abundant in R0mm and R15mm, respectively. KEGG analysis identified 18 proteins from the cysteine and methionine metabolism pathways and nine proteins from the phenylpropanoid biosynthesis pathway. As an important type of IDP related to stress, 30 late embryogenesis abundant proteins were also found. Ten selected proteins with high levels of predicted intrinsic disorder were able to efficiently protect LDH from the freeze-thaw-induced inactivation, but the protective ability was not correlated with the disorder content of these proteins. These observations suggest that protection of the enzymes and other proteins in a stressed cell can be one of the biological functions of plant IDPs.
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Affiliation(s)
- Yun Liu
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University , Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Jiahui Wu
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University , Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Nan Sun
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University , Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Chengjian Tu
- Department of Pharmaceutical Sciences, State University of New York at Buffalo , 285 Kapoor Hall, Buffalo, New York14260, United States
| | - Xiaoying Shi
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University , Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Hua Cheng
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University , Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Simu Liu
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University , Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Shuiming Li
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University , Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Yong Wang
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University , Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Yizhi Zheng
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University , Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
| | - Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida , 12901 Bruce B. Downs Boulevard MDC07, Tampa, Florida 33612, United States
- Laboratory of New Methods in Biology, Institute for Biological Instrumentation of the Russian Academy of Sciences , Institutskaya str., 7, Pushchino, Moscow region 142290, Russia
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Hendus-Altenburger R, Lambrughi M, Terkelsen T, Pedersen SF, Papaleo E, Lindorff-Larsen K, Kragelund BB. A phosphorylation-motif for tuneable helix stabilisation in intrinsically disordered proteins - Lessons from the sodium proton exchanger 1 (NHE1). Cell Signal 2017; 37:40-51. [PMID: 28554535 DOI: 10.1016/j.cellsig.2017.05.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 05/24/2017] [Accepted: 05/25/2017] [Indexed: 11/26/2022]
Abstract
Intrinsically disordered proteins (IDPs) are involved in many pivotal cellular processes including phosphorylation and signalling. The structural and functional effects of phosphorylation of IDPs remain poorly understood and difficult to predict. Thus, a need exists to identify motifs that confer phosphorylation-dependent perturbation of the local preferences for forming e.g. helical structures as well as motifs that do not. The disordered distal tail of the Na+/H+ exchanger 1 (NHE1) is six-times phosphorylated (S693, S723, S726, S771, T779, S785) by the mitogen activated protein kinase 2 (MAPK1, ERK2). Using NMR spectroscopy, we found that two out of those six phosphorylation sites had a stabilizing effect on transient helices. One of these was further investigated by circular dichroism and NMR spectroscopy as well as by molecular dynamic simulations, which confirmed the stabilizing effect and resulted in the identification of a short linear motif for helix stabilisation: [S/T]-P-{3}-[R/K] where [S/T] is the phosphorylation-site. By analysing IDP and phosphorylation site databases we found that the motif is significantly enriched around known phosphorylation sites, supporting a potential wider-spread role in phosphorylation-mediated regulation of intrinsically disordered proteins. The identification of such motifs is important for understanding the molecular mechanism of cellular signalling, and is crucial for the development of predictors for the structural effect of phosphorylation; a tool of relevance for understanding disease-promoting mutations that for example interfere with signalling for instance through constitutive active and often cancer-promoting signalling.
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Affiliation(s)
- Ruth Hendus-Altenburger
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
| | - Matteo Lambrughi
- Computational Biology Laboratory, Center for Autophagy, Recycling and Disease, Strandboulevarden 49, 2100 Copenhagen, Denmark.
| | - Thilde Terkelsen
- Computational Biology Laboratory, Center for Autophagy, Recycling and Disease, Strandboulevarden 49, 2100 Copenhagen, Denmark.
| | - Stine F Pedersen
- Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen Ø, Denmark.
| | - Elena Papaleo
- Computational Biology Laboratory, Center for Autophagy, Recycling and Disease, Strandboulevarden 49, 2100 Copenhagen, Denmark.
| | - Kresten Lindorff-Larsen
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
| | - Birthe B Kragelund
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
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26
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Sarker R, Cha B, Kovbasnjuk O, Cole R, Gabelli S, Tse CM, Donowitz M. Phosphorylation of NHE3-S 719 regulates NHE3 activity through the formation of multiple signaling complexes. Mol Biol Cell 2017; 28:1754-1767. [PMID: 28495796 PMCID: PMC5491184 DOI: 10.1091/mbc.e16-12-0862] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/09/2017] [Accepted: 05/04/2017] [Indexed: 12/02/2022] Open
Abstract
CK2 regulates NHE3 by phosphorylating a single C-terminal amino acid, which, when mutated, reduces basal NHE3 activity and its acute stimulation and inhibition. It also is necessary for binding of proteins throughout the C-terminus, which means that it determines the C-terminal structure. Casein kinase 2 (CK2) binds to the NHE3 C-terminus and constitutively phosphorylates a downstream site (S719) that accounts for 40% of basal NHE3 activity. The role of CK2 in regulation of NHE3 activity in polarized Caco-2/bbe cells was further examined by mutation of NHE3-S719 to A (not phosphorylated) or D (phosphomimetic). NHE3-S719A but not -S719D had multiple changes in NHE3 activity: 1) reduced basal NHE3 activity—specifically, inhibition of the PI3K/AKT-dependent component; 2) reduced acute stimulation of NHE3 activity by LPA/LPA5R stimulation; and 3) reduced acute inhibition of NHE3 activity—specifically, elevated Ca2+ related (carbachol/Ca2+ ionophore), but there was normal inhibition by forskolin and hyperosmolarity. The S719A mutant had reduced NHE3 complex size, reduced expression in lipid rafts, increased BB mobile fraction, and reduced binding to multiple proteins that bind throughout the NHE3 intracellular C-terminus, including calcineurin homologous protein, the NHERF family and SNX27 (related PDZ domains). These studies show that phosphorylation of the NHE3 at a single amino acid in the distal part of the C-terminus affects multiple aspects of NHE3 complex formation and changes the NHE3 lipid raft distribution, which cause changes in specific aspects of basal as well as acutely stimulated and inhibited Na+/H+ exchange activity.
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Affiliation(s)
- Rafiquel Sarker
- Department of Physiology and Department of Medicine, GI Division, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Boyoung Cha
- Department of Physiology and Department of Medicine, GI Division, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Olga Kovbasnjuk
- Department of Physiology and Department of Medicine, GI Division, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Robert Cole
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Sandra Gabelli
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Chung Ming Tse
- Department of Physiology and Department of Medicine, GI Division, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Mark Donowitz
- Department of Physiology and Department of Medicine, GI Division, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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Cancer/Testis Antigens: "Smart" Biomarkers for Diagnosis and Prognosis of Prostate and Other Cancers. Int J Mol Sci 2017; 18:ijms18040740. [PMID: 28362316 PMCID: PMC5412325 DOI: 10.3390/ijms18040740] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Revised: 03/22/2017] [Accepted: 03/27/2017] [Indexed: 12/22/2022] Open
Abstract
A clinical dilemma in the management of prostate cancer (PCa) is to distinguish men with aggressive disease who need definitive treatment from men who may not require immediate intervention. Accurate prediction of disease behavior is critical because radical treatment is associated with high morbidity. Here, we highlight the cancer/testis antigens (CTAs) as potential PCa biomarkers. The CTAs are a group of proteins that are typically restricted to the testis in the normal adult but are aberrantly expressed in several types of cancers. Interestingly, >90% of CTAs are predicted to belong to the realm of intrinsically disordered proteins (IDPs), which do not have unique structures and exist as highly dynamic conformational ensembles, but are known to play important roles in several biological processes. Using prostate-associated gene 4 (PAGE4) as an example of a disordered CTA, we highlight how IDP conformational dynamics may regulate phenotypic heterogeneity in PCa cells, and how it may be exploited both as a potential biomarker as well as a promising therapeutic target in PCa. We also discuss how in addition to intrinsic disorder and post-translational modifications, structural and functional variability induced in the CTAs by alternate splicing represents an important feature that might have different roles in different cancers. Although it is clear that significant additional work needs to be done in the outlined direction, this novel concept emphasizing (multi)functionality as an important trait in selecting a biomarker underscoring the theranostic potential of CTAs that is latent in their structure (or, more appropriately, the lack thereof), and casts them as next generation or “smart” biomarker candidates.
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28
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Cordeiro TN, Herranz-Trillo F, Urbanek A, Estaña A, Cortés J, Sibille N, Bernadó P. Structural Characterization of Highly Flexible Proteins by Small-Angle Scattering. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1009:107-129. [DOI: 10.1007/978-981-10-6038-0_7] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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29
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Hendus-Altenburger R, Pedraz-Cuesta E, Olesen CW, Papaleo E, Schnell JA, Hopper JTS, Robinson CV, Pedersen SF, Kragelund BB. The human Na(+)/H(+) exchanger 1 is a membrane scaffold protein for extracellular signal-regulated kinase 2. BMC Biol 2016; 14:31. [PMID: 27083547 PMCID: PMC4833948 DOI: 10.1186/s12915-016-0252-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 03/29/2016] [Indexed: 11/22/2022] Open
Abstract
Background Extracellular signal-regulated kinase 2 (ERK2) is an S/T kinase with more than 200 known substrates, and with critical roles in regulation of cell growth and differentiation and currently no membrane proteins have been linked to ERK2 scaffolding. Methods and results Here, we identify the human Na+/H+ exchanger 1 (hNHE1) as a membrane scaffold protein for ERK2 and show direct hNHE1-ERK1/2 interaction in cellular contexts. Using nuclear magnetic resonance (NMR) spectroscopy and immunofluorescence analysis we demonstrate that ERK2 scaffolding by hNHE1 occurs by one of three D-domains and by two non-canonical F-sites located in the disordered intracellular tail of hNHE1, mutation of which reduced cellular hNHE1-ERK1/2 co-localization, as well as reduced cellular ERK1/2 activation. Time-resolved NMR spectroscopy revealed that ERK2 phosphorylated the disordered tail of hNHE1 at six sites in vitro, in a distinct temporal order, with the phosphorylation rates at the individual sites being modulated by the docking sites in a distant dependent manner. Conclusions This work characterizes a new type of scaffolding complex, which we term a “shuffle complex”, between the disordered hNHE1-tail and ERK2, and provides a molecular mechanism for the important ERK2 scaffolding function of the membrane protein hNHE1, which regulates the phosphorylation of both hNHE1 and ERK2. Electronic supplementary material The online version of this article (doi:10.1186/s12915-016-0252-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ruth Hendus-Altenburger
- Cell and Developmental Biology, Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100, Copenhagen Ø, Denmark.,Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200, Copenhagen N, Denmark
| | - Elena Pedraz-Cuesta
- Cell and Developmental Biology, Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100, Copenhagen Ø, Denmark
| | - Christina W Olesen
- Cell and Developmental Biology, Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100, Copenhagen Ø, Denmark
| | - Elena Papaleo
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200, Copenhagen N, Denmark
| | - Jeff A Schnell
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200, Copenhagen N, Denmark
| | - Jonathan T S Hopper
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK
| | - Carol V Robinson
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK
| | - Stine F Pedersen
- Cell and Developmental Biology, Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100, Copenhagen Ø, Denmark.
| | - Birthe B Kragelund
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200, Copenhagen N, Denmark.
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30
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Counillon L, Bouret Y, Marchiq I, Pouysségur J. Na(+)/H(+) antiporter (NHE1) and lactate/H(+) symporters (MCTs) in pH homeostasis and cancer metabolism. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2465-80. [PMID: 26944480 DOI: 10.1016/j.bbamcr.2016.02.018] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 02/19/2016] [Accepted: 02/22/2016] [Indexed: 12/17/2022]
Abstract
The Na(+)/H(+)-exchanger NHE1 and the monocarboxylate transporters MCT1 and MCT4 are crucial for intracellular pH regulation, particularly under active metabolism. NHE1, a reversible antiporter, uses the energy provided by the Na(+) gradient to expel H(+) ions generated in the cytosol. The reversible H(+)/lactate(-) symporters MCT1 and 4 cotransport lactate and proton, leading to the net extrusion of lactic acid in glycolytic tumors. In the first two sections of this article we review important features and remaining questions on the structure, biochemical function and cellular roles of these transporters. We then use a fully-coupled mathematical model to simulate their relative contribution to pH regulation in response to lactate production, as it occurs in highly hypoxic and glycolytic tumor cells. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.
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Affiliation(s)
- Laurent Counillon
- University of Nice-Sophia Antipolis, LP2M UMR7370, Faculty of Medicine, 28 Avenue Valombrose, 06107 Nice France; Laboratories of Excellence Ion Channel Science and Therapeutics, France.
| | - Yann Bouret
- University of Nice-Sophia Antipolis, LPMC UMR 7336, 28 Avenue Valrose, 06108 Nice, France
| | - Ibtissam Marchiq
- IRCAN, Centre A. Lacassagne, University of Nice-Sophia Antipolis, 33 Avenue Valombrose, 06107 Nice, France
| | - Jacques Pouysségur
- IRCAN, Centre A. Lacassagne, University of Nice-Sophia Antipolis, 33 Avenue Valombrose, 06107 Nice, France; Centre Scientifique de Monaco (CSM), 8, Quai Antoine 1er, Monaco.
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31
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Sodium-Proton (Na+/H+) Antiporters: Properties and Roles in Health and Disease. Met Ions Life Sci 2016; 16:391-458. [DOI: 10.1007/978-3-319-21756-7_12] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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32
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Aseervatham J, Tran L, Machaca K, Boudker O. The Role of Flexible Loops in Folding, Trafficking and Activity of Equilibrative Nucleoside Transporters. PLoS One 2015; 10:e0136779. [PMID: 26406980 PMCID: PMC4583308 DOI: 10.1371/journal.pone.0136779] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 08/07/2015] [Indexed: 11/25/2022] Open
Abstract
Equilibrative nucleoside transporters (ENTs) are integral membrane proteins, which reside in plasma membranes of all eukaryotic cells and mediate thermodynamically downhill transport of nucleosides. This process is essential for nucleoside recycling, and also plays a key role in terminating adenosine-mediated cellular signaling. Furthermore, ENTs mediate the uptake of many drugs, including anticancer and antiviral nucleoside analogues. The structure and mechanism, by which ENTs catalyze trans-membrane transport of their substrates, remain unknown. To identify the core of the transporter needed for stability, activity, and for its correct trafficking to the plasma membrane, we have expressed human ENT deletion mutants in Xenopus laevis oocytes and determined their localization, transport properties and susceptibility to inhibition. We found that the carboxyl terminal trans-membrane segments are essential for correct protein folding and trafficking. In contrast, the soluble extracellular and intracellular loops appear to be dispensable, and must be involved in the fine-tuning of transport regulation.
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Affiliation(s)
- Jaya Aseervatham
- Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Qatar foundation, Education City, Doha, Qatar
| | - Lucky Tran
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, United States of America
| | - Khaled Machaca
- Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Qatar foundation, Education City, Doha, Qatar
| | - Olga Boudker
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, United States of America
- * E-mail:
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Wallert MA, Hammes D, Nguyen T, Kiefer L, Berthelsen N, Kern A, Anderson-Tiege K, Shabb JB, Muhonen WW, Grove BD, Provost JJ. RhoA Kinase (Rock) and p90 Ribosomal S6 Kinase (p90Rsk) phosphorylation of the sodium hydrogen exchanger (NHE1) is required for lysophosphatidic acid-induced transport, cytoskeletal organization and migration. Cell Signal 2015; 27:498-509. [PMID: 25578862 DOI: 10.1016/j.cellsig.2015.01.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Accepted: 01/03/2015] [Indexed: 12/28/2022]
Abstract
The sodium hydrogen exchanger isoform one (NHE1) plays a critical role coordinating asymmetric events at the leading edge of migrating cells and is regulated by a number of phosphorylation events influencing both the ion transport and cytoskeletal anchoring required for directed migration. Lysophosphatidic acid (LPA) activation of RhoA kinase (Rock) and the Ras-ERK growth factor pathway induces cytoskeletal reorganization, activates NHE1 and induces an increase in cell motility. We report that both Rock I and II stoichiometrically phosphorylate NHE1 at threonine 653 in vitro using mass spectrometry and reconstituted kinase assays. In fibroblasts expressing NHE1 alanine mutants for either Rock (T653A) or ribosomal S6 kinase (Rsk; S703A) we show that each site is partially responsible for the LPA-induced increase in transport activity while NHE1 phosphorylation by either Rock or Rsk at their respective site is sufficient for LPA stimulated stress fiber formation and migration. Furthermore, mutation of either T653 or S703 leads to a higher basal pH level and a significantly higher proliferation rate. Our results identify the direct phosphorylation of NHE1 by Rock and suggest that both RhoA and Ras pathways mediate NHE1-dependent ion transport and migration in fibroblasts.
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Affiliation(s)
- Mark A Wallert
- Minnesota State University Moorhead, Department of Biosciences, Moorhead, MN, USA
| | - Daniel Hammes
- Minnesota State University Moorhead, Department of Biosciences, Moorhead, MN, USA
| | - Tony Nguyen
- Minnesota State University Moorhead, Department of Biosciences, Moorhead, MN, USA
| | - Lea Kiefer
- University of San Diego, Department of Chemistry and Biochemistry, San Diego, CA, USA
| | - Nick Berthelsen
- Minnesota State University Moorhead, Department of Biosciences, Moorhead, MN, USA
| | - Andrew Kern
- Minnesota State University Moorhead, Department of Biosciences, Moorhead, MN, USA
| | | | - John B Shabb
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, USA
| | - Wallace W Muhonen
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, USA
| | - Bryon D Grove
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, USA
| | - Joseph J Provost
- University of San Diego, Department of Chemistry and Biochemistry, San Diego, CA, USA.
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Linxweiler J, Kollipara L, Zahedi RP, Lampel P, Zimmermann R, Greiner M. Proteomic insights into non-small cell lung cancer: New ideas for cancer diagnosis and therapy from a functional viewpoint. EUPA OPEN PROTEOMICS 2014. [DOI: 10.1016/j.euprot.2014.05.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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35
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Uversky VN. Wrecked regulation of intrinsically disordered proteins in diseases: pathogenicity of deregulated regulators. Front Mol Biosci 2014; 1:6. [PMID: 25988147 PMCID: PMC4428494 DOI: 10.3389/fmolb.2014.00006] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 07/06/2014] [Indexed: 12/14/2022] Open
Abstract
Biologically active proteins without stable tertiary structure are common in all known proteomes. Functions of these intrinsically disordered proteins (IDPs) are typically related to regulation, signaling, and control. Cellular levels of these important regulators are tightly regulated by a variety mechanisms ranging from firmly controlled expression to precisely targeted degradation. Functions of IDPs are controlled by binding to specific partners, alternative splicing, and posttranslational modifications among other means. In the norm, right amounts of precisely activated IDPs have to be present in right time at right places. Wrecked regulation brings havoc to the ordered world of disordered proteins, leading to protein misfolding, misidentification, and missignaling that give rise to numerous human diseases, such as cancer, cardiovascular disease, neurodegenerative diseases, and diabetes. Among factors inducing pathogenic transformations of IDPs are various cellular mechanisms, such as chromosomal translocations, damaged splicing, altered expression, frustrated posttranslational modifications, aberrant proteolytic degradation, and defective trafficking. This review presents some of the aspects of deregulated regulation of IDPs leading to human diseases.
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Affiliation(s)
- Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida Tampa, FL, USA ; Biology Department, Faculty of Science, King Abdulaziz University Jeddah, Saudi Arabia ; Laboratory of New Methods in Biology, Institute for Biological Instrumentation, Russian Academy of Sciences Moscow, Russia
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36
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Alves C, Ma Y, Li X, Fliegel L. Characterization of human mutations in phosphorylatable amino acids of the cytosolic regulatory tail of SLC9A1. Biochem Cell Biol 2014; 92:524-9. [PMID: 25162926 DOI: 10.1139/bcb-2014-0071] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The NHE1 isoform of the mammalian Na(+)/H(+) exchanger is a ubiquitous plasma membrane protein that regulates intracellular pH in cells by removing one intracellular proton in exchange for one extracellular sodium. Genetic defects in NHE1 have been shown to affect the growth and motor ability of mice, but mutations in humans have not been studied. NHE1 has a cytosolic C-terminal regulatory domain of approximately 300 amino acids. We investigated the functional effects of two human mutations found in the regulatory phosphorylatable amino acids Ser(703) and Ser(771). A Ser703Pro mutant protein had essentially the same activity, expression, and targeting as the wild type NHE1 protein. In contrast, the Ser771Pro protein had reduced activity and expression of NHE1 protein, though cell surface targeting was normal. In dual pulse assays the Ser771Pro mutant was not further activated by sustained intracellular acidosis but displayed an unusual activation by brief pulses of acidosis. The results demonstrate that the Ser771Pro human genetic mutation has significant and detrimental physiological effects on the activity of the NHE1 protein, SLC9A1.
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Affiliation(s)
- Claudia Alves
- Department of Biochemistry, University Alberta, Edmonton, AB T6G 2H7, Canada
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37
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Hendus-Altenburger R, Kragelund BB, Pedersen SF. Structural dynamics and regulation of the mammalian SLC9A family of Na⁺/H⁺ exchangers. CURRENT TOPICS IN MEMBRANES 2014; 73:69-148. [PMID: 24745981 DOI: 10.1016/b978-0-12-800223-0.00002-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Mammalian Na⁺/H⁺ exchangers of the SLC9A family are widely expressed and involved in numerous essential physiological processes. Their primary function is to mediate the 1:1 exchange of Na⁺ for H⁺ across the membrane in which they reside, and they play central roles in regulation of body, cellular, and organellar pH. Their function is tightly regulated through mechanisms involving interactions with multiple protein and lipid-binding partners, phosphorylations, and other posttranslational modifications. Biochemical and mutational analyses indicate that the SLC9As have a short intracellular N-terminus, 12 transmembrane (TM) helices necessary and sufficient for ion transport, and a C-terminal cytoplasmic tail region with essential regulatory roles. No high-resolution structures of the SLC9As exist; however, models based on crystal structures of the bacterial NhaAs support the 12 TM organization and suggest that TMIV and XI may form a central part of the ion-translocation pathway, whereas pH sensing may involve TMII, TMIX, and several intracellular loops. Similar to most ion transporters studied, SLC9As likely exist as coupled dimers in the membrane, and this appears to be important for the well-studied cooperativity of H⁺ binding. The aim of this work is to summarize and critically discuss the currently available evidence on the structural dynamics, regulation, and binding partner interactions of SLC9As, focusing in particular on the most widely studied isoform, SLC9A1/NHE1. Further, novel bioinformatic and structural analyses are provided that to some extent challenge the existing paradigm on how ions are transported by mammalian SLC9As.
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Affiliation(s)
- Ruth Hendus-Altenburger
- Section for Biomolecular Sciences, Department of Biology, University of Copenhagen, Copenhagen, Denmark; Section for Cell and Developmental Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Birthe B Kragelund
- Section for Biomolecular Sciences, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Stine Falsig Pedersen
- Section for Cell and Developmental Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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Rösner HI, Kragelund BB. Structure and dynamic properties of membrane proteins using NMR. Compr Physiol 2013; 2:1491-539. [PMID: 23798308 DOI: 10.1002/cphy.c110036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Integral membrane proteins are one of the most challenging groups of macromolecules despite their apparent conformational simplicity. They manage and drive transport, circulate information, and participate in cellular movements via interactions with other proteins and through intricate conformational changes. Their structural and functional decoding is challenging and has imposed demanding experimental development. Solution nuclear magnetic resonance (NMR) spectroscopy is one of the techniques providing the capacity to make a significant difference in the deciphering of the membrane protein structure-function paradigm. The method has evolved dramatically during the last decade resulting in a plethora of new experiments leading to a significant increase in the scientific repertoire for studying membrane proteins. Besides solving the three-dimensional structures using state-of-the-art approaches, a large variety of developments of well-established techniques are available providing insight into membrane protein flexibility, dynamics, and interactions. Inspired by the speed of development in the application of new strategies, by invention of methods to measure solvent accessibility and describe low-populated states, this review seeks to introduce the vast possibilities solution NMR can offer to the study of membrane protein structure-function analyses with special focus on applicability.
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Affiliation(s)
- Heike I Rösner
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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39
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Structural and functional insights into the cardiac Na+/H+ exchanger. J Mol Cell Cardiol 2013; 61:60-7. [DOI: 10.1016/j.yjmcc.2012.11.019] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 11/26/2012] [Accepted: 11/28/2012] [Indexed: 11/19/2022]
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40
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Iešmantavičius V, Jensen MR, Ozenne V, Blackledge M, Poulsen FM, Kjaergaard M. Modulation of the Intrinsic Helix Propensity of an Intrinsically Disordered Protein Reveals Long-Range Helix–Helix Interactions. J Am Chem Soc 2013; 135:10155-63. [DOI: 10.1021/ja4045532] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
| | - Malene Ringkjøbing Jensen
- Institut de Biologie Structurale Jean-Pierre Ebel, CEA-CNRS-UJF UMR 5075,
41 rue Jules Horowitz, 38027 Grenoble, France
| | - Valéry Ozenne
- Institut de Biologie Structurale Jean-Pierre Ebel, CEA-CNRS-UJF UMR 5075,
41 rue Jules Horowitz, 38027 Grenoble, France
| | - Martin Blackledge
- Institut de Biologie Structurale Jean-Pierre Ebel, CEA-CNRS-UJF UMR 5075,
41 rue Jules Horowitz, 38027 Grenoble, France
| | - Flemming M. Poulsen
- Department
of Biology, University of Copenhagen, 1017
København K, Copenhagen,
Denmark
| | - Magnus Kjaergaard
- Department
of Biology, University of Copenhagen, 1017
København K, Copenhagen,
Denmark
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41
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Provost JJ, Wallert MA. Inside out: targeting NHE1 as an intracellular and extracellular regulator of cancer progression. Chem Biol Drug Des 2013; 81:85-101. [PMID: 23253131 DOI: 10.1111/cbdd.12035] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The sodium hydrogen exchanger isoform one is a critical regulator of intracellular pH, serves as an anchor for the formation of cytoplasmic signaling complexes, and modulates cytoskeletal organization. There is a growing interest in the potential for sodium hydrogen exchanger isoform one as a therapeutic target against cancer. Sodium hydrogen exchanger isoform one transport drives formation of membrane protrusions essential for cell migration and contributes to the establishment of a tumor microenvironment that leads to the rearrangement of the extracellular matrix further supporting tumor progression. Here, we focus on the potential impact that an inexpensive, $100 genome would have in identifying prospective therapeutic targets to treat tumors based upon changes in gene expression and variation of sodium hydrogen exchanger isoform one regulators. In particular, we will focus on the ezrin, radixin, moesin family proteins, calcineurin B homologous proteins, Ras/Raf/MEK/ERK signaling, and phosphoinositide signaling as they relate to the regulation of sodium hydrogen exchanger isoform one in cancer progression.
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Affiliation(s)
- Joseph J Provost
- Center for Biopharmaceutical Research and Production, North Dakota State University, Fargo, ND 58102, USA.
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42
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Uversky VN. The most important thing is the tail: multitudinous functionalities of intrinsically disordered protein termini. FEBS Lett 2013; 587:1891-901. [PMID: 23665034 DOI: 10.1016/j.febslet.2013.04.042] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 04/24/2013] [Accepted: 04/29/2013] [Indexed: 01/29/2023]
Abstract
Many functional proteins do not have well-folded structures in their substantial parts, representing hybrids that possess both ordered and disordered regions. Disorder is unevenly distributed within these hybrid proteins and is typically more common at protein termini. Disordered tails are engaged in a wide range of functions, some of which are unique for termini and cannot be found in other disordered parts of a protein. This review covers some of the key functions of disordered protein termini and emphasizes that these tails are not simple flexible protrusions but are evolved to serve.
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Affiliation(s)
- Vladimir N Uversky
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA.
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43
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Structural changes in the C-terminal regulatory region of the Na⁺/H⁺ exchanger mediate phosphorylation induced regulation. J Mol Cell Cardiol 2013; 61:153-63. [PMID: 23602949 DOI: 10.1016/j.yjmcc.2013.04.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 03/21/2013] [Accepted: 04/09/2013] [Indexed: 11/23/2022]
Abstract
The Na(+)/H(+) exchanger isoform 1 (NHE1) is a plasma membrane pH regulatory protein that removes one intracellular H(+) in exchange for an extracellular Na(+). NHE1 is regulated by phosphorylation of the cytoplasmic regulatory region and amino acids Ser(770) and Ser(771) of the regulatory domain are necessary for activation by sustained intracellular acidosis. The phosphomimetic mutations (S770D/S771D) resulted in an activated form of the protein. Immunoprecipitation of full length NHE1 protein showed that the phosphomimetic mutant had increased sensitivity to digestion with trypsin indicating a conformational change. Tryptic digestion of purified C-terminal regulatory region showed that the S770D/S771D mutation altered sensitivity to trypsin digestion. Wild type and phosphomimetic purified C-terminal region (577-815) of human NHE1 were compared and tryptophan fluorescence indicated that there were pH-dependent differences in the conformation of the proteins. Native polyacrylamide gel electrophoresis demonstrated that the phosphomimetic mutant had a more compact structure. Bottom-up hydrogen/deuterium exchange mass spectrometry demonstrated that a peptide fragment containing the phosphomimetic mutations became strongly stabilized relative to the wild type protein. Overall, the results suggested that phosphorylation of S770/S771 changes the conformation of the C-terminal regulatory region in a pH-dependent manner, resulting in a more compact region that affects NHE1 activity. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes".
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44
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Structural characterization of intrinsically disordered proteins by the combined use of NMR and SAXS. Biochem Soc Trans 2013; 40:955-62. [PMID: 22988847 DOI: 10.1042/bst20120149] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In recent years, IDPs (intrinsically disordered proteins) have emerged as pivotal actors in biology. Despite IDPs being present in all kingdoms of life, they are more abundant in eukaryotes where they are involved in the vast majority of regulation and signalling processes. The realization that, in some cases, functional states of proteins were partly or fully disordered was in contradiction to the traditional view where a well defined three-dimensional structure was required for activity. Several experimental evidences indicate, however, that structural features in IDPs such as transient secondary-structural elements and overall dimensions are crucial to their function. NMR has been the main tool to study IDP structure by probing conformational preferences at residue level. Additionally, SAXS (small-angle X-ray scattering) has the capacity to report on the three-dimensional space sampled by disordered states and therefore complements the local information provided by NMR. The present review describes how the synergy between NMR and SAXS can be exploited to obtain more detailed structural and dynamic models of IDPs in solution. These combined strategies, embedded into computational approaches, promise the elucidation of the structure-function properties of this important, but elusive, family of biomolecules.
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Regulation of the cardiac Na⁺/H⁺ exchanger in health and disease. J Mol Cell Cardiol 2013; 61:68-76. [PMID: 23429007 DOI: 10.1016/j.yjmcc.2013.02.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 02/07/2013] [Accepted: 02/11/2013] [Indexed: 11/21/2022]
Abstract
The Na(+) gradient produced across the cardiac sarcolemma by the ATP-dependent Na(+)-pump is a constant source of energy for Na(+)-dependent transporters. The plasma membrane Na(+)/H(+) exchanger (NHE) is one such secondary active transporter, regulating intracellular pH, Na(+) concentration, and cell volume. NHE1, the major isoform found in the heart, is activated in response to a variety of stimuli such as hormones and mechanical stress. This important characteristic of NHE1 is intimately linked to heart diseases, including maladaptive cardiac hypertrophy and subsequent heart failure, as well as acute ischemic-reperfusion injury. NHE1 activation results in elevation of pH and intracellular Na(+) concentration, which potentially enhance downstream signaling cascades in the myocardium. Therefore, in addition to determining the mechanism underlying regulation of NHE1 activity, it is important to understand how the ionic signal produced by NHE1 is transmitted to the downstream targets. Extensive studies have identified many accessory factors that interact with NHE1. Here, we have summarized the recent progress on understanding the molecular mechanism underlying NHE1 regulation and have shown a possible signaling pathway leading to cardiac remodeling, which is initiated from NHE1. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes".
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Lambrughi M, Papaleo E, Testa L, Brocca S, De Gioia L, Grandori R. Intramolecular interactions stabilizing compact conformations of the intrinsically disordered kinase-inhibitor domain of Sic1: a molecular dynamics investigation. Front Physiol 2012. [PMID: 23189058 PMCID: PMC3504315 DOI: 10.3389/fphys.2012.00435] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Cyclin-dependent kinase inhibitors (CKIs) are key regulatory proteins of the eukaryotic cell cycle, which modulate cyclin-dependent kinase (Cdk) activity. CKIs perform their inhibitory effect by the formation of ternary complexes with a target kinase and its cognate cyclin. These regulators generally belong to the class of intrinsically disordered proteins (IDPs), which lack a well-defined and organized three-dimensional (3D) structure in their free state, undergoing folding upon binding to specific partners. Unbound IDPs are not merely random-coil structures, but can present intrinsically folded structural units (IFSUs) and collapsed conformations. These structural features can be relevant to protein function in vivo. The yeast CKI Sic1 is a 284-amino acid IDP that binds to Cdk1 in complex with the Clb5,6 cyclins, preventing phosphorylation of G1 substrates and, therefore, entrance to the S phase. Sic1 degradation, triggered by multiple phosphorylation events, promotes cell-cycle progression. Previous experimental studies pointed out a propensity of Sic1 and its isolated domains to populate both extended and compact conformations. The present contribution provides models for compact conformations of the Sic1 kinase-inhibitory domain (KID) by all-atom molecular dynamics (MD) simulations in explicit solvent and in the absence of interactors. The results are integrated by spectroscopic and spectrometric data. Helical IFSUs are identified, along with networks of intramolecular interactions. The results identify a group of putative hub residues and networks of electrostatic interactions, which are likely to be involved in the stabilization of the globular states.
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Affiliation(s)
- Matteo Lambrughi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca Milan, Italy
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Characterization of cytoskeletal protein 4.1R interaction with NHE1 (Na(+)/H(+) exchanger isoform 1). Biochem J 2012; 446:427-35. [PMID: 22731252 DOI: 10.1042/bj20120535] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
NHE1 (Na(+)/H(+) exchanger isoform 1) has been reported to be hyperactive in 4.1R-null erythrocytes [Rivera, De Franceschi, Peters, Gascard, Mohandas and Brugnara (2006) Am. J. Physiol. Cell Physiol. 291, C880-C886], supporting a functional interaction between NHE1 and 4.1R. In the present paper we demonstrate that 4.1R binds directly to the NHE1cd (cytoplasmic domain of NHE1) through the interaction of an EED motif in the 4.1R FERM (4.1/ezrin/radixin/moesin) domain with two clusters of basic amino acids in the NHE1cd, K(519)R and R(556)FNKKYVKK, previously shown to mediate PIP(2) (phosphatidylinositol 4,5-bisphosphate) binding [Aharonovitz, Zaun, Balla, York, Orlowski and Grinstein (2000) J. Cell. Biol. 150, 213-224]. The affinity of this interaction (K(d) = 100-200 nM) is reduced in hypertonic and acidic conditions, demonstrating that this interaction is of an electrostatic nature. The binding affinity is also reduced upon binding of Ca(2+)/CaM (Ca(2+)-saturated calmodulin) to the 4.1R FERM domain. We propose that 4.1R regulates NHE1 activity through a direct protein-protein interaction that can be modulated by intracellular pH and Na(+) and Ca(2+) concentrations.
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48
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Arrigoni A, Grillo B, Vitriolo A, De Gioia L, Papaleo E. C-terminal acidic domain of ubiquitin-conjugating enzymes: A multi-functional conserved intrinsically disordered domain in family 3 of E2 enzymes. J Struct Biol 2012; 178:245-59. [DOI: 10.1016/j.jsb.2012.04.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2011] [Revised: 04/01/2012] [Accepted: 04/03/2012] [Indexed: 11/30/2022]
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Kjaergaard M, Poulsen FM. Disordered proteins studied by chemical shifts. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2012; 60:42-51. [PMID: 22293398 DOI: 10.1016/j.pnmrs.2011.10.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 10/06/2011] [Indexed: 05/31/2023]
Affiliation(s)
- Magnus Kjaergaard
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 København N, Denmark
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50
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Schedlbauer A, Gandini R, Kontaxis G, Paulmichl M, Furst J, Konrat R. The C-terminus of ICln is natively disordered but displays local structural preformation. Cell Physiol Biochem 2011; 28:1203-10. [PMID: 22179008 DOI: 10.1159/000335852] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2011] [Indexed: 11/19/2022] Open
Abstract
ICln is a vital, ubiquitously expressed protein with roles in cell volume regulation, angiogenesis, cell morphology, activation of platelets and RNA processing. In previous work we have determined the 3D structure of the N-terminus of ICln (residues 1-159), which folds into a PH-like domain followed by an unstructured region (residues H134 - Q159) containing protein-protein interaction sites. Here we present sequence-specific resonance assignments of the C-terminus (residues Q159 - H235) of ICln by NMR, and show that this region of the protein is intrinsically unstructured. By applying (13)Cα- (13)Cβ secondary chemical shifts to detect possible preferences for secondary structure elements we show that the C-terminus of ICln adopts a preferred α-helical organization between residues E170 and E187, and exists preferentially in extended conformations (β-strands) between residues D161 to Y168 and E217 to T223.
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