1
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Mawla GD, Kamal SM, Cao LY, Purhonen P, Hebert H, Sauer RT, Baker TA, Römling U. The membrane-cytoplasmic linker defines activity of FtsH proteases in Pseudomonas aeruginosa clone C. J Biol Chem 2024; 300:105622. [PMID: 38176647 PMCID: PMC10850787 DOI: 10.1016/j.jbc.2023.105622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 12/22/2023] [Accepted: 12/27/2023] [Indexed: 01/06/2024] Open
Abstract
Pandemic Pseudomonas aeruginosa clone C strains encode two inner-membrane associated ATP-dependent FtsH proteases. PaftsH1 is located on the core genome and supports cell growth and intrinsic antibiotic resistance, whereas PaftsH2, a xenolog acquired through horizontal gene transfer from a distantly related species, is unable to functionally replace PaftsH1. We show that purified PaFtsH2 degrades fewer substrates than PaFtsH1. Replacing the 31-amino acid-extended linker region of PaFtsH2 spanning from the C-terminal end of the transmembrane helix-2 to the first seven highly divergent residues of the cytosolic AAA+ ATPase module with the corresponding region of PaFtsH1 improves hybrid-enzyme substrate processing in vitro and enables PaFtsH2 to substitute for PaFtsH1 in vivo. Electron microscopy indicates that the identity of this linker sequence influences FtsH flexibility. We find membrane-cytoplasmic (MC) linker regions of PaFtsH1 characteristically glycine-rich compared to those from FtsH2. Consequently, introducing three glycines into the membrane-proximal end of PaFtsH2's MC linker is sufficient to elevate its activity in vitro and in vivo. Our findings establish that the efficiency of substrate processing by the two PaFtsH isoforms depends on MC linker identity and suggest that greater linker flexibility and/or length allows FtsH to degrade a wider spectrum of substrates. As PaFtsH2 homologs occur across bacterial phyla, we hypothesize that FtsH2 is a latent enzyme but may recognize specific substrates or is activated in specific contexts or biological niches. The identity of such linkers might thus play a more determinative role in the functionality of and physiological impact by FtsH proteases than previously thought.
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Affiliation(s)
- Gina D Mawla
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Shady M Kamal
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm; Sweden
| | - Lian-Ying Cao
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm; Sweden
| | - Pasi Purhonen
- Department of Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, Huddinge; Sweden
| | - Hans Hebert
- Department of Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, Huddinge; Sweden
| | - Robert T Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Tania A Baker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
| | - Ute Römling
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm; Sweden.
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2
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Kim H, Lenoir S, Helfricht A, Jung T, Karneva ZK, Lee Y, Beumer W, van der Horst GB, Anthonijsz H, Buil LC, van der Ham F, Platenburg GJ, Purhonen P, Hebert H, Humbert S, Saudou F, Klein P, Song JJ. A pathogenic proteolysis-resistant huntingtin isoform induced by an antisense oligonucleotide maintains huntingtin function. JCI Insight 2022; 7:154108. [PMID: 35943803 PMCID: PMC9536263 DOI: 10.1172/jci.insight.154108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 08/03/2022] [Indexed: 11/17/2022] Open
Abstract
Huntington’s disease (HD) is a late-onset neurological disorder for which therapeutics are not available. Its key pathological mechanism involves the proteolysis of polyglutamine-expanded (polyQ-expanded) mutant huntingtin (mHTT), which generates N-terminal fragments containing polyQ, a key contributor to HD pathogenesis. Interestingly, a naturally occurring spliced form of HTT mRNA with truncated exon 12 encodes an HTT (HTTΔ12) with a deletion near the caspase-6 cleavage site. In this study, we used a multidisciplinary approach to characterize the therapeutic potential of targeting HTT exon 12. We show that HTTΔ12 was resistant to caspase-6 cleavage in both cell-free and tissue lysate assays. However, HTTΔ12 retained overall biochemical and structural properties similar to those of wt-HTT. We generated mice in which HTT exon 12 was truncated and found that the canonical exon 12 was dispensable for the main physiological functions of HTT, including embryonic development and intracellular trafficking. Finally, we pharmacologically induced HTTΔ12 using the antisense oligonucleotide (ASO) QRX-704. QRX-704 showed predictable pharmacology and efficient biodistribution. In addition, it was stable for several months and inhibited pathogenic proteolysis. Furthermore, QRX-704 treatments resulted in a reduction of HTT aggregation and an increase in dendritic spine count. Thus, ASO-induced HTT exon 12 splice switching from HTT may provide an alternative therapeutic strategy for HD.
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Affiliation(s)
- Hyeongju Kim
- Department of Biological Sciences, KAIST (Korea Advanced Institute of Science and Technology), Daejeon, Korea, Republic of
| | - Sophie Lenoir
- Grenoble Institute Neurosciences, University Grenoble Alpes, Grenoble, France
| | | | - Taeyang Jung
- Department of Biological Sciences, KAIST (Korea Advanced Institute of Science and Technology), Daejeon, Korea, Republic of
| | | | - Yejin Lee
- Department of Biological Sciences, KAIST (Korea Advanced Institute of Science and Technology), Daejeon, Korea, Republic of
| | | | | | | | | | | | | | - Pasi Purhonen
- Department of Biomedical Engineering and Health Systems, The Royal Institute of Technology, KTH, Huddinge, Sweden
| | - Hans Hebert
- Department of Biomedical Engineering and Health Systems, The Royal Institute of Technology, KTH, Huddinge, Sweden
| | - Sandrine Humbert
- Grenoble Institute Neurosciences, University Grenoble Alpes, Grenoble, France
| | - Frédéric Saudou
- Grenoble Institute Neurosciences, University Grenoble Alpes, Grenoble, France
| | | | - Ji-Joon Song
- Department of Biological Sciences, KAIST (Korea Advanced Institute of Science and Technology), Daejeon, Korea, Republic of
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3
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Lee E, Kang C, Purhonen P, Hebert H, Bouazoune K, Hohng S, Song JJ. A Novel N-terminal Region to Chromodomain in CHD7 is Required for the Efficient Remodeling Activity. J Mol Biol 2021; 433:167114. [PMID: 34161779 DOI: 10.1016/j.jmb.2021.167114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 05/31/2021] [Accepted: 06/15/2021] [Indexed: 10/21/2022]
Abstract
Chromodomain-Helicase DNA binding protein 7 (CHD7) is an ATP dependent chromatin remodeler involved in maintaining open chromatin structure. Mutations of CHD7 gene causes multiple developmental disorders, notably CHARGE syndrome. However, there is not much known about the molecular mechanism by which CHD7 remodels nucleosomes. Here, we performed biochemical and biophysical analysis on CHD7 chromatin remodeler and uncover that N-terminal to the Chromodomain (N-CRD) interacts with nucleosome and contains a high conserved arginine stretch, which is reminiscent of arginine anchor. Importantly, this region is required for efficient ATPase stimulation and nucleosome remodeling activity of CHD7. Furthermore, smFRET analysis shows the mutations in the N-CRD causes the defects in remodeling activity. Collectively, our results uncover the functional importance of a previously unidentified N-terminal region in CHD7 and implicate that the multiple domains in chromatin remodelers are involved in regulating their activities.
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Affiliation(s)
- Eunhye Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), KAIST Institute of BioCentury, Daejeon 34141, Korea
| | - Chanshin Kang
- Department of Physics and Astronomy, Institute of Applied Physics, Seoul National University, Seoul 08826, Korea
| | - Pasi Purhonen
- School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, S-141 52 Huddinge, Sweden
| | - Hans Hebert
- School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, S-141 52 Huddinge, Sweden
| | - Karim Bouazoune
- Institut für Molekularbiologie und Tumorforschung (IMT), Biomedizinisches Forschungszentrum, Philipps-Universität Marburg, Marburg 35043, Germany
| | - Sungchul Hohng
- Department of Physics and Astronomy, Institute of Applied Physics, Seoul National University, Seoul 08826, Korea.
| | - Ji-Joon Song
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), KAIST Institute of BioCentury, Daejeon 34141, Korea.
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Koulakiotis NS, Purhonen P, Gikas E, Hebert H, Tsarbopoulos A. Publisher Correction: Crocus-derived compounds alter the aggregation pathway of Alzheimer's Disease - associated beta amyloid protein. Sci Rep 2021; 11:3315. [PMID: 33531654 PMCID: PMC7854578 DOI: 10.1038/s41598-021-82907-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
| | - Pasi Purhonen
- School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, S‑141 52, Huddinge, Sweden
| | - Evangelos Gikas
- Department of Pharmacy, National and Kapodistrian University of Athens, 15771, Athens, Greece
| | - Hans Hebert
- School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, S‑141 52, Huddinge, Sweden
| | - Anthony Tsarbopoulos
- GAIA Research Center, Bioanalytical Department, The Goulandris Natural History Museum, 14562, Kifissia, Greece. .,Department of Pharmacology, National and Kapodistrian University of Athens Medical School, 75 Mikras Asias Street, 11527, Athens, Greece.
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5
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Kumar RB, Purhonen P, Hebert H, Jegerschöld C. Arachidonic acid promotes the binding of 5-lipoxygenase on nanodiscs containing 5-lipoxygenase activating protein in the absence of calcium-ions. PLoS One 2020; 15:e0228607. [PMID: 32645009 PMCID: PMC7347166 DOI: 10.1371/journal.pone.0228607] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 06/07/2020] [Indexed: 12/20/2022] Open
Abstract
Among the first steps in inflammation is the conversion of arachidonic acid (AA) stored in the cell membranes into leukotrienes. This occurs mainly in leukocytes and depends on the interaction of two proteins: 5-lipoxygenase (5LO), stored away from the nuclear membranes until use and 5-lipoxygenase activating protein (FLAP), a transmembrane, homotrimeric protein, constitutively present in nuclear membrane. We could earlier visualize the binding of 5LO to nanodiscs in the presence of Ca2+-ions by the use of transmission electron microscopy (TEM) on samples negatively stained by sodium phosphotungstate. In the absence of Ca2+-ions 5LO did not bind to the membrane. In the present communication, FLAP reconstituted in the nanodiscs which could be purified if the His-tag was located on the FLAP C-terminus but not the N-terminus. Our aim was to find out if 1) 5LO would bind in a Ca2+-dependent manner also when FLAP is present? 2) Would the substrate (AA) have effects on 5LO binding to FLAP-nanodiscs? TEM was used to assess the complex formation between 5LO and FLAP-nanodiscs along with, sucrose gradient purification, gel-electrophoresis and mass spectrometry. It was found that presence of AA by itself induces complex formation in the absence of added calcium. This finding corroborates that AA is necessary for the complex formation and that a Ca2+-flush is mainly needed for the recruitment of 5LO to the membrane. Our results also showed that the addition of Ca2+-ions promoted binding of 5LO on the FLAP-nanodiscs as was also the case for nanodiscs without FLAP incorporated. In the absence of added substances no 5LO-FLAP complex was formed. Another finding is that the formation of a 5LO-FLAP complex appears to induce fragmentation of 5LO in vitro.
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Affiliation(s)
| | - Pasi Purhonen
- Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden
- Division of Structural Biotechnology, Department of Biomedical Engineering and Health Systems, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology, Stockholm, Sweden
| | - Hans Hebert
- Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden
- Division of Structural Biotechnology, Department of Biomedical Engineering and Health Systems, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology, Stockholm, Sweden
| | - Caroline Jegerschöld
- Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden
- Division of Structural Biotechnology, Department of Biomedical Engineering and Health Systems, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology, Stockholm, Sweden
- * E-mail:
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6
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Sarr M, Kronqvist N, Chen G, Aleksis R, Purhonen P, Hebert H, Jaudzems K, Rising A, Johansson J. A spidroin-derived solubility tag enables controlled aggregation of a designed amyloid protein. FEBS J 2018; 285:1873-1885. [PMID: 29604175 DOI: 10.1111/febs.14451] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 03/08/2018] [Accepted: 03/26/2018] [Indexed: 12/31/2022]
Abstract
Amyloidogenesis is associated with more than 30 diseases, but the molecular mechanisms involved in cell toxicity and fibril formation remain largely unknown. The inherent tendency of amyloid-forming proteins to aggregate renders expression, purification, and experimental studies challenging. NT* is a solubility tag derived from a spider silk protein that was recently introduced for the production of several aggregation-prone peptides and proteins at high yields. Herein, we investigate whether fusion to NT* can prevent amyloid fibril formation and enable controlled aggregation for experimental studies. As an example of an amyloidogenic protein, we chose the de novo-designed polypeptide β17. The fusion protein NT*-β17 was recombinantly expressed in Escherichia coli to produce high amounts of soluble and mostly monomeric protein. Structural analysis showed that β17 is kept in a largely unstructured conformation in fusion with NT*. After proteolytic release, β17 adopts a β-sheet conformation in a pH- and salt-dependent manner and assembles into amyloid-like fibrils. The ability of NT* to prevent premature aggregation and to enable structural studies of prefibrillar states may facilitate investigation of proteins involved in amyloid diseases.
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Affiliation(s)
- Médoune Sarr
- Division for Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Huddinge, Sweden
| | - Nina Kronqvist
- Division for Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Huddinge, Sweden
| | - Gefei Chen
- Division for Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Huddinge, Sweden
| | - Rihards Aleksis
- Department of Physical Organic Chemistry, Latvian Institute of Organic Synthesis, Riga, Latvia
| | - Pasi Purhonen
- Department of Biosciences and Nutrition, Karolinska Institutet, and School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Huddinge, Sweden
| | - Hans Hebert
- Department of Biosciences and Nutrition, Karolinska Institutet, and School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Huddinge, Sweden
| | - Kristaps Jaudzems
- Department of Physical Organic Chemistry, Latvian Institute of Organic Synthesis, Riga, Latvia
| | - Anna Rising
- Division for Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Huddinge, Sweden.,Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Jan Johansson
- Division for Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Huddinge, Sweden
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7
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Kuang Q, Purhonen P, Pattipaka T, Ayele YH, Hebert H, Koeck PJB. A Refined Single-Particle Reconstruction Procedure to Process Two-Dimensional Crystal Images from Transmission Electron Microscopy. Microsc Microanal 2015; 21:876-885. [PMID: 25990985 DOI: 10.1017/s1431927615000616] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Single-particle reconstruction (SPR) and electron crystallography (EC), two major applications in electron microscopy, can be used to determine the structure of membrane proteins. The three-dimensional (3D) map is obtained from separated particles in conventional SPR, but from periodic unit cells in EC. Here, we report a refined SPR procedure for processing 2D crystal images. The method is applied to 2D crystals of melibiose permease, a secondary transporter in Escherichia coli. The current procedure is improved from our previously published one in several aspects. The "gold standard Fourier shell correlation" resolution of our final reconstruction reaches 13 Å, which is significantly better than the previously obtained 17 Å resolution. The choices of different refinement parameters for reconstruction are discussed. Our refined SPR procedure could be applied to determine the structure of other membrane proteins in small or locally distorted 2D crystals, which are not ideal for EC.
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Affiliation(s)
- Qie Kuang
- Karolinska Institutet,Department of Biosciences and Nutrition and KTH Royal Institute of Technology,School of Technology and Health,Novum,S-14183 Huddinge,Sweden
| | - Pasi Purhonen
- Karolinska Institutet,Department of Biosciences and Nutrition and KTH Royal Institute of Technology,School of Technology and Health,Novum,S-14183 Huddinge,Sweden
| | - Thirupathi Pattipaka
- Karolinska Institutet,Department of Biosciences and Nutrition and KTH Royal Institute of Technology,School of Technology and Health,Novum,S-14183 Huddinge,Sweden
| | - Yohannes H Ayele
- Karolinska Institutet,Department of Biosciences and Nutrition and KTH Royal Institute of Technology,School of Technology and Health,Novum,S-14183 Huddinge,Sweden
| | - Hans Hebert
- Karolinska Institutet,Department of Biosciences and Nutrition and KTH Royal Institute of Technology,School of Technology and Health,Novum,S-14183 Huddinge,Sweden
| | - Philip J B Koeck
- Karolinska Institutet,Department of Biosciences and Nutrition and KTH Royal Institute of Technology,School of Technology and Health,Novum,S-14183 Huddinge,Sweden
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8
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Abstract
Potassium channels ubiquitously exist in nearly all kingdoms of life and perform diverse but important functions. Since the first atomic structure of a prokaryotic potassium channel (KcsA, a channel from Streptomyces lividans) was determined, tremendous progress has been made in understanding the mechanism of potassium channels and channels conducting other ions. In this review, we discuss the structure of various kinds of potassium channels, including the potassium channel with the pore-forming domain only (KcsA), voltage-gated, inwardly rectifying, tandem pore domain, and ligand-gated ones. The general properties shared by all potassium channels are introduced first, followed by specific features in each class. Our purpose is to help readers to grasp the basic concepts, to be familiar with the property of the different domains, and to understand the structure and function of the potassium channels better.
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Affiliation(s)
- Qie Kuang
- Department of Biosciences and Nutrition, Karolinska Institutet, Novum, 14183, Huddinge, Sweden.
- School of Technology and Health, KTH Royal Institute of Technology, Novum, 14183, Huddinge, Sweden.
| | - Pasi Purhonen
- Department of Biosciences and Nutrition, Karolinska Institutet, Novum, 14183, Huddinge, Sweden
| | - Hans Hebert
- Department of Biosciences and Nutrition, Karolinska Institutet, Novum, 14183, Huddinge, Sweden
- School of Technology and Health, KTH Royal Institute of Technology, Novum, 14183, Huddinge, Sweden
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9
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Kuang Q, Purhonen P, Jegerschöld C, Koeck PJB, Hebert H. Free RCK arrangement in Kch, a putative escherichia coli potassium channel, as suggested by electron crystallography. Structure 2014; 23:199-205. [PMID: 25497729 DOI: 10.1016/j.str.2014.10.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 10/08/2014] [Accepted: 10/21/2014] [Indexed: 01/24/2023]
Abstract
The ligand-gated potassium channels are stimulated by various kinds of messengers. Previous studies showed that ligand-gated potassium channels containing RCK domains (the regulator of the conductance of potassium ion) form a dimer of tetramer structure through the RCK octameric gating ring in the presence of detergent. Here, we have analyzed the structure of Kch, a channel of this type from Escherichia coli, in a lipid environment using electron crystallography. By combining information from the 3D map of the transmembrane part of the protein and docking of an atomic model of a potassium channel, we conclude that the RCK domains face the solution and that an RCK octameric gating ring arrangement does not form under our crystallization condition. Our findings may be applied to other potassium channels that have an RCK gating ring arrangement.
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Affiliation(s)
- Qie Kuang
- Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden; School of Technology and Health, KTH Royal Institute of Technology, 14183 Huddinge, Sweden.
| | - Pasi Purhonen
- Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden
| | - Caroline Jegerschöld
- Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden
| | - Philip J B Koeck
- Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden; School of Technology and Health, KTH Royal Institute of Technology, 14183 Huddinge, Sweden
| | - Hans Hebert
- Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden; School of Technology and Health, KTH Royal Institute of Technology, 14183 Huddinge, Sweden.
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10
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Kuang Q, Purhonen P, Jegerschöld C, Hebert H. The projection structure of Kch, a putative potassium channel in Escherichia coli, by electron crystallography. Biochim Biophys Acta 2013; 1838:237-43. [PMID: 24055821 DOI: 10.1016/j.bbamem.2013.09.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Revised: 09/07/2013] [Accepted: 09/10/2013] [Indexed: 11/30/2022]
Abstract
The kch gene, the only potassium channel gene in Escherichia coli, has the property to express both full-length Kch and its cytosolic domain (RCK) due to a methionine at position 240. The RCK domains are believed to form an octameric ring structure and regulate the gating of the potassium channels after having bound certain ligands. Several different gating ring structures have been reported for the soluble RCK domains, however, these were studied isolated from their transmembrane parts. We previously reported an octameric structure of Kch in solution by electron microscopy and single particle reconstruction, composed of two tetrameric full-length proteins through RCK interaction. To exclude the effect of the detergent, we have now performed an electron crystallographic study of the full-length Kch in membrane bound form. Well-ordered two-dimensional crystals were grown in a natural phospholipid environment. A projection map merged from the fifteen best images extended to 6Å resolution. The c12 two-sided plane group of the two-dimensional crystals showed that Kch crystallized as two symmetrically related overlapping layers. The arrangement suggests that the two layers of RCK domains are shifted with respect to each other and the RCK octameric gating ring of Kch does not form under the crystallization condition.
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Affiliation(s)
- Qie Kuang
- Karolinska Institutet, Dept of Biosciences and Nutrition and KTH Royal Institute of Technology, School of Technology and Health, Novum, S-14183 Huddinge, Sweden.
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11
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Lambert W, Koeck PJB, Ahrman E, Purhonen P, Cheng K, Elmlund D, Hebert H, Emanuelsson C. Subunit arrangement in the dodecameric chloroplast small heat shock protein Hsp21. Protein Sci 2010; 20:291-301. [PMID: 21280121 DOI: 10.1002/pro.560] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Revised: 10/02/2010] [Accepted: 11/06/2010] [Indexed: 11/07/2022]
Abstract
Unfolding proteins are prevented from irreversible aggregation by small heat shock proteins (sHsps) through interactions that depend on a dynamic equilibrium between sHsp subunits and sHsp oligomers. A chloroplast-localized sHsp, Hsp21, provides protection to client proteins to increase plant stress resistance. Structural information is lacking concerning the oligomeric conformation of this sHsp. We here present a structure model of Arabidopsis thaliana Hsp21, obtained by homology modeling, single-particle electron microscopy, and lysine-specific chemical crosslinking. The model shows that the Hsp21 subunits are arranged in two hexameric discs, similar to a cytosolic plant sHsp homolog that has been structurally determined after crystallization. However, the two hexameric discs of Hsp21 are rotated by 25° in relation to each other, suggesting a role for global dynamics in dodecamer function.
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Affiliation(s)
- Wietske Lambert
- Department of Biochemistry and Structural Biology, Center for Molecular Protein Science, Lund University, Sweden.
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12
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Hebert H, Jegerschöld C, Purhonen P, Bhakat P, Gheorghe K, Gyobu N, Mitsuoka K, Pawelzik S, Jakobsson PJ, Morgenstern R. Structure of microsomal prostaglandin E synthase 1 as determined by electron crystallography. Acta Crystallogr A 2009. [DOI: 10.1107/s010876730909850x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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13
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Koeck PJ, Purhonen P, Alvang R, Grundberg B, Hebert H. Single particle refinement in electron crystallography: A pilot study. J Struct Biol 2007; 160:344-52. [DOI: 10.1016/j.jsb.2007.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2007] [Revised: 08/24/2007] [Accepted: 09/03/2007] [Indexed: 11/25/2022]
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Purhonen P, Thomsen K, Maunsbach AB, Hebert H. Association of renal Na,K-ATPase alpha-subunit with the beta- and gamma-subunits based on cryoelectron microscopy. J Membr Biol 2007; 214:139-46. [PMID: 17557166 DOI: 10.1007/s00232-006-0056-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Revised: 11/29/2006] [Indexed: 11/28/2022]
Abstract
Na,K-ATPase transports Na(+) and K(+) across cell membranes and consists of alpha- and beta-subunits. Na,K-ATPase also associates with small FXYD proteins that regulate the activity of the pump. We have used cryoelectron microscopy of two-dimensional crystals including data to 8 A resolution to determine the three-dimensional (3-D) structure of renal Na,K-ATPase containing FXYD2, the gamma-subunit. A homology model for the alpha-subunit was calculated from a Ca(2+)-ATPase structure and used to locate the additional beta- and gamma-subunits present in the 3-D map of Na,K-ATPase. Based on the 3-D map, the beta-subunit is located close to transmembrane helices M8 and M10 and the gamma-subunit is adjacent to helices M2 and M9 of the alpha-subunit.
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Affiliation(s)
- P Purhonen
- Department of Biosciences and Nutrition and School of Technology and Health, Karolinska Institutet, Royal Institute of Technology, S-141 57, Huddinge, Sweden
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Purhonen P, Lundbäck AK, Lemonnier R, Leblanc G, Hebert H. Three-dimensional structure of the sugar symporter melibiose permease from cryo-electron microscopy. J Struct Biol 2005; 152:76-83. [PMID: 16139519 DOI: 10.1016/j.jsb.2005.07.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Revised: 07/08/2005] [Accepted: 07/12/2005] [Indexed: 10/25/2022]
Abstract
Melibiose permease (MelB) of Escherichia coli is a secondary transporter that couples the uptake of melibiose and various other galactosides to symport of cations that can be Na+, Li+ or H+. MelB belongs to the glycoside-pentoside-hexuronide: cation symporter family of porters and is suggested to have 12 transmembrane helices. We have determined the three-dimensional structure of MelB at 10A resolution in the membrane plane with cryo-electron microscopy from two-dimensional crystals. The three-dimensional map shows a heart-shaped molecule composed of two domains with a large central cavity between them. The structure is constricted at one side of the membrane while it is open to the other. The overall molecular shape resembles those of lactose permease and glycerol-3-phosphate transporter. However, organization of helices in MelB seems less symmetrical than in these two members of the major facilitator superfamily.
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Affiliation(s)
- Pasi Purhonen
- Karolinska Institutet, Department of Biosciences at Novum, S-141 57 Huddinge,Sweden
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16
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Abstract
The molecular structure of Na,K-ATPase was determined by electron crystallography from two-dimensional crystals induced in purified membranes isolated from the outer medulla of pig kidney. The P2 type unit cell contains two protomers in the E(2) conformation, each of them with a size of 65 x 75 x 150 A(3). The alpha, beta, and gamma subunits in the membrane crystals were demonstrated in the crystals with Western blotting and related to distinct domains in the density map. The alpha subunit corresponds to most of the density in the transmembrane region as well as to the large hydrophilic headpiece on the cytoplasmic side of the membrane. The headpiece is divided into three separated domains. One of these gives rise to an elongated projection onto the membrane plane, while the putative nucleotide binding and phosphorylation domains form compact densities in the rest of the cytoplasmic part of the structure. Density on the extracellular face corresponds to the protein part of the beta subunit. Ten helices from the catalytic a subunit correspond to two groups of distinct densities in the transmembrane region. The structure of the lipid bilayer spanning part also suggests positions for the transmembrane helices from the beta and gamma subunits. The overall structure of the alpha subunit of Na,K-ATPase as determined here by cryo-electron microscopy is similar to the X-ray structure of Ca-ATPase. However, conformational changes between the E(1) and E(2) forms are suggested by different relative positions of cytoplasmic domains.
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Affiliation(s)
- Hans Hebert
- Karolinska Institutet, Department of Biosciences, Center for Structural Biochemistry, Novum, S-141 57 Huddinge, Sweden.
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17
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Hacksell I, Rigaud JL, Purhonen P, Pourcher T, Hebert H, Leblanc G. Projection structure at 8 A resolution of the melibiose permease, an Na-sugar co-transporter from Escherichia coli. EMBO J 2002; 21:3569-74. [PMID: 12110569 PMCID: PMC126123 DOI: 10.1093/emboj/cdf378] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The ion-coupled sugar membrane symporter or co-transporter melibiose permease (MelB), responsible for alpha-galactoside accumulation in Escherichia coli, is a representative member of the glycoside-pentoside- hexuronide family of the vast class of electrochemical potential-driven porters. Pure solubilized preparations of a MelB recombinant protein were subjected to two-dimensional crystallization trials and several crystal forms were observed. Two of these appeared as large wide tubes suitable for analysis by electron crystallography. Flattened tubes on carbon support film, embedded in amorphous ice prior to electron cryomicroscopy, showed two-sided plane group symmetries P12(1) or P222(1), with unit cell dimensions a = 89.9 A, b = 51.6 A, gamma = 91.9 degrees and a = 188.9 A, b = 48.8 A, gamma = 90 degrees, respectively. The projection map from the P222(1 )crystals at 8 A resolution displayed an asymmetric protein unit consisting of two domains lining a central and curve-shaped cleft. Together, the MelB monomer could host the 12 predicted transmembrane alpha-helices. Overall, the MelB helix packing arrangement compared more favorably with that of the Na(+)/H(+) antiporter NhaA than that of the oxalate antiporter.
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Affiliation(s)
| | - Jean-Louis Rigaud
- Karolinska Institutet, Department of Biosciences, S-141 57 Huddinge, Sweden,
Institut Curie, UMR-CNRS 168 and LRC-CEA 8, 11 rue Pierre et Marie Curie, 75231 Paris cedex 05 and UMR 6078 CNRS-Université de Nice and LRC CEA 16, 06230 Villefranche-sur-mer, France Corresponding author e-mail:
| | | | - Thierry Pourcher
- Karolinska Institutet, Department of Biosciences, S-141 57 Huddinge, Sweden,
Institut Curie, UMR-CNRS 168 and LRC-CEA 8, 11 rue Pierre et Marie Curie, 75231 Paris cedex 05 and UMR 6078 CNRS-Université de Nice and LRC CEA 16, 06230 Villefranche-sur-mer, France Corresponding author e-mail:
| | - Hans Hebert
- Karolinska Institutet, Department of Biosciences, S-141 57 Huddinge, Sweden,
Institut Curie, UMR-CNRS 168 and LRC-CEA 8, 11 rue Pierre et Marie Curie, 75231 Paris cedex 05 and UMR 6078 CNRS-Université de Nice and LRC CEA 16, 06230 Villefranche-sur-mer, France Corresponding author e-mail:
| | - Gérard Leblanc
- Karolinska Institutet, Department of Biosciences, S-141 57 Huddinge, Sweden,
Institut Curie, UMR-CNRS 168 and LRC-CEA 8, 11 rue Pierre et Marie Curie, 75231 Paris cedex 05 and UMR 6078 CNRS-Université de Nice and LRC CEA 16, 06230 Villefranche-sur-mer, France Corresponding author e-mail:
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Hebert H, Purhonen P, Vorum H, Thomsen K, Maunsbach AB. Three-dimensional structure of renal Na,K-ATPase from cryo-electron microscopy of two-dimensional crystals. J Mol Biol 2001; 314:479-94. [PMID: 11846561 DOI: 10.1006/jmbi.2001.5137] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The structure of Na, K-ATPase was determined by electron crystallography at 9.5 A from multiple small 2-D crystals induced in purified membranes isolated from the outer medulla of pig kidney. The density map shows a protomer stabilized in the E(2) conformation which extends approximately 65 A x 75 A x 150 A in the asymmetric unit of the P2 type unit cell. The alpha, beta, and gamma subunits were demonstrated in the membrane crystals with Western blotting and related to distinct domains in the density map. The alpha subunit corresponds to most of the density in the transmembrane region as well as the large hydrophilic headpiece on the cytoplasmic side of the membrane. The headpiece is divided into three separated domains, which are similar in overall shape to the domains of the calcium pump of the sarcoplasmic reticulum. One of these domains gives rise to a characteristic elongated projection onto the membrane plane while the putative nucleotide binding and phosphorylation domains form comparatively compact densities in the rest of the cytoplasmic part of the structure. Density on the extracellular face corresponds to the protein part of the beta subunit and is located as an extension of the transmembrane region perpendicular to the membrane plane. The structure of the lipid bilayer spanning part suggests the positions for the transmembrane helix from the beta subunit as well as the small gamma subunit present in this Na,K-ATPase. Two groups of ten helices from the catalytic alpha subunit corresponds to the remaining density in the transmembrane region. The present results demonstrate distinct similarities between the structure of the alpha subunit of Na,K-ATPase as determined here by cryo-electron microscopy and the reported X-ray structure of Ca-ATPase. However, conformational changes between the E(1) and E(2) forms are suggested by different relative positions of cytoplasmatic domains.
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Affiliation(s)
- H Hebert
- Karolinska Institutet Department of Biosciences, Center for Structural Biochemistry, Novum, Huddinge, S-141 57, Sweden.
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Purhonen P, Pursiainen K, Reunanen H. Effects of brefeldin A on autophagy in cultured rat fibroblasts. Eur J Cell Biol 1997; 74:63-7. [PMID: 9309391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Effects of brefeldin A on cellular autophagy were studied in cultured rat fibroblasts. Brefeldin A inhibits the activation and membrane-binding properties of most ADP-ribosylation factors and causes the redistribution of Golgi proteins into the endoplasmic reticulum. Immunofluorescence and enzyme cytochemical methods revealed the disappearance of the Golgi apparatus and trans-Golgi network during the brefeldin A incubation. The volume fractions of autophagic vacuoles increased about threefold in cells treated with brefeldin A for 4 h and about sixfold in serum-deprived cells as compared with controls. When cells were first treated with brefeldin A for 1 h and were then deprived of serum and treated with brefeldin A for 3 h, the volume fraction of autophagic vacuoles increased about 4.5-fold as compared with untreated cells. The results showed that brefeldin A is unable to prevent serum deprivation-induced accumulation of autophagic vacuoles and that brefeldin A even when acting alone increases the volume fraction of autophagic vacuoles. It was concluded that an intact Golgi apparatus and trans-Golgi network are not essential for the formation of autophagic vacuoles. It seems also probable that ADP-ribosylation factors are not needed when vacuoles are formed.
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Affiliation(s)
- P Purhonen
- Department of Cell Biology, University of Jyväskylä, Finland
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