1
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Selvasingh JA, McDonald EF, Neufer PD, McKinney JR, Meiler J, Ledwitch KV. Dark nanodiscs for evaluating membrane protein thermostability by differential scanning fluorimetry. Biophys J 2024; 123:68-79. [PMID: 37978799 PMCID: PMC10808023 DOI: 10.1016/j.bpj.2023.11.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 10/27/2023] [Accepted: 11/16/2023] [Indexed: 11/19/2023] Open
Abstract
Measuring protein thermostability provides valuable information on the biophysical rules that govern the structure-energy relationships of proteins. However, such measurements remain a challenge for membrane proteins. Here, we introduce a new experimental system to evaluate membrane protein thermostability. This system leverages a recently developed nonfluorescent membrane scaffold protein to reconstitute proteins into nanodiscs and is coupled with a nano-format of differential scanning fluorimetry (nanoDSF). This approach offers a label-free and direct measurement of the intrinsic tryptophan fluorescence of the membrane protein as it unfolds in solution without signal interference from the "dark" nanodisc. In this work, we demonstrate the application of this method using the disulfide bond formation protein B (DsbB) as a test membrane protein. NanoDSF measurements of DsbB reconstituted in dark nanodiscs loaded with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dimyristoyl-sn-glycero-3-phosphorylglycerol (DMPG) lipids show a complex biphasic thermal unfolding pattern with a minor unfolding transition followed by a major transition. The inflection points of the thermal denaturation curve reveal two distinct unfolding midpoint melting temperatures (Tm) of 70.5°C and 77.5°C, consistent with a three-state unfolding model. Further, we show that the catalytically conserved disulfide bond between residues C41 and C130 drives the intermediate state of the unfolding pathway for DsbB in a DMPC and DMPG nanodisc. To extend the utility of this method, we evaluate and compare the thermostability of DsbB in different lipid environments. We introduce this method as a new tool that can be used to understand how compositionally and biophysically complex lipid environments drive membrane protein stability.
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Affiliation(s)
- Jazlyn A Selvasingh
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee
| | - Eli F McDonald
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee
| | - Preston D Neufer
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee
| | - Jacob R McKinney
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee; Institute of Drug Discovery, Faculty of Medicine, University of Leipzig, Leipzig, Germany.
| | - Kaitlyn V Ledwitch
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee.
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2
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Necelis M, McDermott C, Belcher Dufrisne M, Baryiames C, Columbus L. Solution NMR investigations of integral membrane proteins: Challenges and innovations. Curr Opin Struct Biol 2023; 82:102654. [PMID: 37542910 PMCID: PMC10529709 DOI: 10.1016/j.sbi.2023.102654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 05/08/2023] [Accepted: 06/20/2023] [Indexed: 08/07/2023]
Abstract
Compared to soluble protein counterparts, the understanding of membrane protein stability, solvent interactions, and function are not as well understood. Recent advancements in labeling, expression, and stabilization of membrane proteins have enabled solution nuclear magnetic resonance spectroscopy to investigate membrane protein conformational states, ligand binding, lipid interactions, stability, and folding. This review highlights these advancements and new understandings and provides examples of recent applications.
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Affiliation(s)
- Matthew Necelis
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Connor McDermott
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | | | | | - Linda Columbus
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA.
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3
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Rollins J, Worthington T, Dransfield A, Whitney J, Stanford J, Hooke E, Hobson J, Wengler J, Hope S, Mizrachi D. Expression of Cell-Adhesion Molecules in E. coli: A High Throughput Screening to Identify Paracellular Modulators. Int J Mol Sci 2023; 24:9784. [PMID: 37372932 DOI: 10.3390/ijms24129784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 05/31/2023] [Accepted: 06/02/2023] [Indexed: 06/29/2023] Open
Abstract
Cell-adhesion molecules (CAMs) are responsible for cell-cell, cell-extracellular matrix, and cell-pathogen interactions. Claudins (CLDNs), occludin (OCLN), and junctional adhesion molecules (JAMs) are CAMs' components of the tight junction (TJ), the single protein structure tasked with safeguarding the paracellular space. The TJ is responsible for controlling paracellular permeability according to size and charge. Currently, there are no therapeutic solutions to modulate the TJ. Here, we describe the expression of CLDN proteins in the outer membrane of E. coli and report its consequences. When the expression is induced, the unicellular behavior of E. coli is replaced with multicellular aggregations that can be quantified using Flow Cytometry (FC). Our method, called iCLASP (inspection of cell-adhesion molecules aggregation through FC protocols), allows high-throughput screening (HTS) of small-molecules for interactions with CAMs. Here, we focused on using iCLASP to identify paracellular modulators for CLDN2. Furthermore, we validated those compounds in the mammalian cell line A549 as a proof-of-concept for the iCLASP method.
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Affiliation(s)
- Jay Rollins
- Department of Cell Biology and Physiology, College of Life Sciences, Brigham Young University, Provo, UT 84602, USA
| | - Tyler Worthington
- Department of Cell Biology and Physiology, College of Life Sciences, Brigham Young University, Provo, UT 84602, USA
| | - Allison Dransfield
- Department of Cell Biology and Physiology, College of Life Sciences, Brigham Young University, Provo, UT 84602, USA
| | - Jordan Whitney
- Department of Cell Biology and Physiology, College of Life Sciences, Brigham Young University, Provo, UT 84602, USA
| | - Jordan Stanford
- Department of Cell Biology and Physiology, College of Life Sciences, Brigham Young University, Provo, UT 84602, USA
| | - Emily Hooke
- Department of Cell Biology and Physiology, College of Life Sciences, Brigham Young University, Provo, UT 84602, USA
| | - Joseph Hobson
- Department of Cell Biology and Physiology, College of Life Sciences, Brigham Young University, Provo, UT 84602, USA
| | - Jacob Wengler
- Department of Cell Biology and Physiology, College of Life Sciences, Brigham Young University, Provo, UT 84602, USA
| | - Sandra Hope
- Department of Microbiology and Molecular Biology, College of Life Sciences, Brigham Young University, Provo, UT 84602, USA
| | - Dario Mizrachi
- Department of Cell Biology and Physiology, College of Life Sciences, Brigham Young University, Provo, UT 84602, USA
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4
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Ledwitch KV, Künze G, McKinney JR, Okwei E, Larochelle K, Pankewitz L, Ganguly S, Darling HL, Coin I, Meiler J. Sparse pseudocontact shift NMR data obtained from a non-canonical amino acid-linked lanthanide tag improves integral membrane protein structure prediction. JOURNAL OF BIOMOLECULAR NMR 2023; 77:69-82. [PMID: 37016190 PMCID: PMC10443207 DOI: 10.1007/s10858-023-00412-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 03/20/2023] [Indexed: 06/19/2023]
Abstract
A single experimental method alone often fails to provide the resolution, accuracy, and coverage needed to model integral membrane proteins (IMPs). Integrating computation with experimental data is a powerful approach to supplement missing structural information with atomic detail. We combine RosettaNMR with experimentally-derived paramagnetic NMR restraints to guide membrane protein structure prediction. We demonstrate this approach using the disulfide bond formation protein B (DsbB), an α-helical IMP. Here, we attached a cyclen-based paramagnetic lanthanide tag to an engineered non-canonical amino acid (ncAA) using a copper-catalyzed azide-alkyne cycloaddition (CuAAC) click chemistry reaction. Using this tagging strategy, we collected 203 backbone HN pseudocontact shifts (PCSs) for three different labeling sites and used these as input to guide de novo membrane protein structure prediction protocols in Rosetta. We find that this sparse PCS dataset combined with 44 long-range NOEs as restraints in our calculations improves structure prediction of DsbB by enhancements in model accuracy, sampling, and scoring. The inclusion of this PCS dataset improved the Cα-RMSD transmembrane segment values of the best-scoring and best-RMSD models from 9.57 Å and 3.06 Å (no NMR data) to 5.73 Å and 2.18 Å, respectively.
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Affiliation(s)
- Kaitlyn V Ledwitch
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA.
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA.
- Department of Chemistry, Center for Structural Biology, MRBIII 5154E, Vanderbilt University, Nashville, TN, 37212, USA.
| | - Georg Künze
- Institute of Drug Discovery, Faculty of Medicine, University of Leipzig, 04103, Leipzig, Germany
| | - Jacob R McKinney
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Elleansar Okwei
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Katherine Larochelle
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Lisa Pankewitz
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Soumya Ganguly
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Heather L Darling
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Irene Coin
- Institute of Biochemistry, Faculty of Life Science, University of Leipzig, 04103, Leipzig, Germany
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
- Institute of Drug Discovery, Faculty of Medicine, University of Leipzig, 04103, Leipzig, Germany
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5
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Selvasingh JA, McDonald EF, Mckinney JR, Meiler J, Ledwitch KV. Dark nanodiscs as a model membrane for evaluating membrane protein thermostability by differential scanning fluorimetry. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.08.539917. [PMID: 37214798 PMCID: PMC10197605 DOI: 10.1101/2023.05.08.539917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Measuring protein thermostability provides valuable information on the biophysical rules that govern structure-energy relationships of proteins. However, such measurements remain a challenge for membrane proteins. Here, we introduce a new experimental system to evaluate membrane protein thermostability. This system leverages a recently-developed non-fluorescent membrane scaffold protein (MSP) to reconstitute proteins into nanodiscs and is coupled with a nano-format of differential scanning fluorimetry (nanoDSF). This approach offers a label-free and direct measurement of the intrinsic tryptophan fluorescence of the membrane protein as it unfolds in solution without signal interference from the "dark" nanodisc. In this work, we demonstrate the application of this method using the disulfide bond formation protein B (DsbB) as a test membrane protein. NanoDSF measurements of DsbB reconstituted in dark nanodiscs show a complex biphasic thermal unfolding pattern in the presence of lipids with a minor unfolding transition followed by a major transition. The inflection points of the thermal denaturation curve reveal two distinct unfolding midpoint melting temperatures (Tm) of 70.5 °C and 77.5 °C, consistent with a three-state unfolding model. Further, we show that the catalytically conserved disulfide bond between residues C41 and C130 drives the intermediate state of the unfolding pathway for DsbB in a nanodisc. We introduce this method as a new tool that can be used to understand how compositionally, and biophysically complex lipid environments drive membrane protein stability.
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Affiliation(s)
- Jazlyn A. Selvasingh
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Eli Fritz McDonald
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Jacob R. Mckinney
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Institute of Drug Discovery, Faculty of Medicine, University of Leipzig, 04103 Leipzig, Germany
| | - Kaitlyn V. Ledwitch
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Lead contact
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6
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Li W. Distinct enzymatic strategies for de novo generation of disulfide bonds in membranes. Crit Rev Biochem Mol Biol 2023; 58:36-49. [PMID: 37098102 PMCID: PMC10460286 DOI: 10.1080/10409238.2023.2201404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 04/02/2023] [Accepted: 04/06/2023] [Indexed: 04/26/2023]
Abstract
Disulfide bond formation is a catalyzed reaction essential for the folding and stability of proteins in the secretory pathway. In prokaryotes, disulfide bonds are generated by DsbB or VKOR homologs that couple the oxidation of a cysteine pair to quinone reduction. Vertebrate VKOR and VKOR-like enzymes have gained the epoxide reductase activity to support blood coagulation. The core structures of DsbB and VKOR variants share the architecture of a four-transmembrane-helix bundle that supports the coupled redox reaction and a flexible region containing another cysteine pair for electron transfer. Despite considerable similarities, recent high-resolution crystal structures of DsbB and VKOR variants reveal significant differences. DsbB activates the cysteine thiolate by a catalytic triad of polar residues, a reminiscent of classical cysteine/serine proteases. In contrast, bacterial VKOR homologs create a hydrophobic pocket to activate the cysteine thiolate. Vertebrate VKOR and VKOR-like maintain this hydrophobic pocket and further evolved two strong hydrogen bonds to stabilize the reaction intermediates and increase the quinone redox potential. These hydrogen bonds are critical to overcome the higher energy barrier required for epoxide reduction. The electron transfer process of DsbB and VKOR variants uses slow and fast pathways, but their relative contribution may be different in prokaryotic and eukaryotic cells. The quinone is a tightly bound cofactor in DsbB and bacterial VKOR homologs, whereas vertebrate VKOR variants use transient substrate binding to trigger the electron transfer in the slow pathway. Overall, the catalytic mechanisms of DsbB and VKOR variants have fundamental differences.
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Affiliation(s)
- Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
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7
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Miao Q, Nitsche C, Orton H, Overhand M, Otting G, Ubbink M. Paramagnetic Chemical Probes for Studying Biological Macromolecules. Chem Rev 2022; 122:9571-9642. [PMID: 35084831 PMCID: PMC9136935 DOI: 10.1021/acs.chemrev.1c00708] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Indexed: 12/11/2022]
Abstract
Paramagnetic chemical probes have been used in electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectroscopy for more than four decades. Recent years witnessed a great increase in the variety of probes for the study of biological macromolecules (proteins, nucleic acids, and oligosaccharides). This Review aims to provide a comprehensive overview of the existing paramagnetic chemical probes, including chemical synthetic approaches, functional properties, and selected applications. Recent developments have seen, in particular, a rapid expansion of the range of lanthanoid probes with anisotropic magnetic susceptibilities for the generation of structural restraints based on residual dipolar couplings and pseudocontact shifts in solution and solid state NMR spectroscopy, mostly for protein studies. Also many new isotropic paramagnetic probes, suitable for NMR measurements of paramagnetic relaxation enhancements, as well as EPR spectroscopic studies (in particular double resonance techniques) have been developed and employed to investigate biological macromolecules. Notwithstanding the large number of reported probes, only few have found broad application and further development of probes for dedicated applications is foreseen.
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Affiliation(s)
- Qing Miao
- Leiden
Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2333 CC, The Netherlands
- School
of Chemistry &Chemical Engineering, Shaanxi University of Science & Technology, Xi’an710021, China
| | - Christoph Nitsche
- Research
School of Chemistry, The Australian National
University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
| | - Henry Orton
- Research
School of Chemistry, The Australian National
University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
- ARC
Centre of Excellence for Innovations in Peptide & Protein Science,
Research School of Chemistry, Australian
National University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
| | - Mark Overhand
- Leiden
Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2333 CC, The Netherlands
| | - Gottfried Otting
- Research
School of Chemistry, The Australian National
University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
- ARC
Centre of Excellence for Innovations in Peptide & Protein Science,
Research School of Chemistry, Australian
National University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
| | - Marcellus Ubbink
- Leiden
Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2333 CC, The Netherlands
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8
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Interplay between DsbA1, DsbA2 and C8J_1298 Periplasmic Oxidoreductases of Campylobacter jejuni and Their Impact on Bacterial Physiology and Pathogenesis. Int J Mol Sci 2021; 22:ijms222413451. [PMID: 34948248 PMCID: PMC8708908 DOI: 10.3390/ijms222413451] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/08/2021] [Accepted: 12/10/2021] [Indexed: 01/13/2023] Open
Abstract
The bacterial proteins of the Dsb family catalyze the formation of disulfide bridges between cysteine residues that stabilize protein structures and ensure their proper functioning. Here, we report the detailed analysis of the Dsb pathway of Campylobacter jejuni. The oxidizing Dsb system of this pathogen is unique because it consists of two monomeric DsbAs (DsbA1 and DsbA2) and one dimeric bifunctional protein (C8J_1298). Previously, we showed that DsbA1 and C8J_1298 are redundant. Here, we unraveled the interaction between the two monomeric DsbAs by in vitro and in vivo experiments and by solving their structures and found that both monomeric DsbAs are dispensable proteins. Their structures confirmed that they are homologs of EcDsbL. The slight differences seen in the surface charge of the proteins do not affect the interaction with their redox partner. Comparative proteomics showed that several respiratory proteins, as well as periplasmic transport proteins, are targets of the Dsb system. Some of these, both donors and electron acceptors, are essential elements of the C. jejuni respiratory process under oxygen-limiting conditions in the host intestine. The data presented provide detailed information on the function of the C. jejuni Dsb system, identifying it as a potential target for novel antibacterial molecules.
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9
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Meirson T, Bomze D, Markel G. Structural basis of SARS-CoV-2 spike protein induced by ACE2. Bioinformatics 2021; 37:929-936. [PMID: 32818261 PMCID: PMC7558967 DOI: 10.1093/bioinformatics/btaa744] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 07/20/2020] [Accepted: 08/14/2020] [Indexed: 12/24/2022] Open
Abstract
Motivation The recent emergence of the novel SARS-coronavirus 2 (SARS-CoV-2) and its international
spread pose a global health emergency. The spike (S) glycoprotein binds ACE2 and
promotes SARS-CoV-2 entry into host cells. The trimeric S protein binds the receptor
using the receptor-binding domain (RBD) causing conformational changes in S protein that
allow priming by host cell proteases. Unraveling the dynamic structural features used by
SARS-CoV-2 for entry might provide insights into viral transmission and reveal novel
therapeutic targets. Using structures determined by X-ray crystallography and cryo-EM,
we performed structural analysis and atomic comparisons of the different conformational
states adopted by the SARS-CoV-2-RBD. Results Here, we determined the key structural components induced by the receptor and
characterized their intramolecular interactions. We show that κ-helix (polyproline-II)
is a predominant structure in the binding interface and in facilitating the conversion
to the active form of the S protein. We demonstrate a series of conversions between
switch-like κ-helix and β-strand, and conformational variations in a set of short
α-helices which affect the hinge region. These conformational changes lead to an
alternating pattern in conserved disulfide bond configurations positioned at the hinge,
indicating a possible disulfide exchange, an important allosteric switch implicated in
viral entry of various viruses, including HIV and murine coronavirus. The structural
information presented herein enables to inspect and understand the important dynamic
features of SARS-CoV-2-RBD and propose a novel potential therapeutic strategy to block
viral entry. Overall, this study provides guidance for the design and optimization of
structure-based intervention strategies that target SARS-CoV-2. Availability We have implemented the proposed methods in an R package freely available at https://github.com/Grantlab/bio3d Supplementary information Supplementary data are
available at Bioinformatics online.
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Affiliation(s)
- Tomer Meirson
- Ella Lemelbaum Institute for Immuno-oncology, Sheba Medical Center, Ramat-Gan 526260, Israel.,The Azrieli Faculty of Medicine, Bar-Ilan University, Safed 1311502, Israel
| | | | - Gal Markel
- Ella Lemelbaum Institute for Immuno-oncology, Sheba Medical Center, Ramat-Gan 526260, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel.,Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
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10
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Fake It 'Till You Make It-The Pursuit of Suitable Membrane Mimetics for Membrane Protein Biophysics. Int J Mol Sci 2020; 22:ijms22010050. [PMID: 33374526 PMCID: PMC7793082 DOI: 10.3390/ijms22010050] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 12/17/2020] [Accepted: 12/19/2020] [Indexed: 12/13/2022] Open
Abstract
Membrane proteins evolved to reside in the hydrophobic lipid bilayers of cellular membranes. Therefore, membrane proteins bridge the different aqueous compartments separated by the membrane, and furthermore, dynamically interact with their surrounding lipid environment. The latter not only stabilizes membrane proteins, but directly impacts their folding, structure and function. In order to be characterized with biophysical and structural biological methods, membrane proteins are typically extracted and subsequently purified from their native lipid environment. This approach requires that lipid membranes are replaced by suitable surrogates, which ideally closely mimic the native bilayer, in order to maintain the membrane proteins structural and functional integrity. In this review, we survey the currently available membrane mimetic environments ranging from detergent micelles to bicelles, nanodiscs, lipidic-cubic phase (LCP), liposomes, and polymersomes. We discuss their respective advantages and disadvantages as well as their suitability for downstream biophysical and structural characterization. Finally, we take a look at ongoing methodological developments, which aim for direct in-situ characterization of membrane proteins within native membranes instead of relying on membrane mimetics.
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11
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Liu S, Li S, Yang Y, Li W. Termini restraining of small membrane proteins enables structure determination at near-atomic resolution. SCIENCE ADVANCES 2020; 6:6/51/eabe3717. [PMID: 33355146 DOI: 10.1126/sciadv.abe3717] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 11/04/2020] [Indexed: 06/12/2023]
Abstract
Small membrane proteins are difficult targets for structural characterization. Here, we stabilize their folding by restraining their amino and carboxyl termini with associable protein entities, exemplified by the two halves of a superfolder GFP. The termini-restrained proteins are functional and show improved stability during overexpression and purification. The reassembled GFP provides a versatile scaffold for membrane protein crystallization, enables diffraction to atomic resolution, and facilitates crystal identification, phase determination, and density modification. This strategy gives rise to 14 new structures of five vertebrate proteins from distinct functional families, bringing a substantial expansion to the structural database of small membrane proteins. Moreover, a high-resolution structure of bacterial DsbB reveals that this thiol oxidoreductase is activated through a catalytic triad, similar to cysteine proteases. Overall, termini restraining proves exceptionally effective for stabilization and structure determination of small membrane proteins.
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Affiliation(s)
- Shixuan Liu
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Shuang Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Yihu Yang
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.
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12
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Yeh V, Goode A, Bonev BB. Membrane Protein Structure Determination and Characterisation by Solution and Solid-State NMR. BIOLOGY 2020; 9:E396. [PMID: 33198410 PMCID: PMC7697852 DOI: 10.3390/biology9110396] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 11/08/2020] [Accepted: 11/11/2020] [Indexed: 12/25/2022]
Abstract
Biological membranes define the interface of life and its basic unit, the cell. Membrane proteins play key roles in membrane functions, yet their structure and mechanisms remain poorly understood. Breakthroughs in crystallography and electron microscopy have invigorated structural analysis while failing to characterise key functional interactions with lipids, small molecules and membrane modulators, as well as their conformational polymorphism and dynamics. NMR is uniquely suited to resolving atomic environments within complex molecular assemblies and reporting on membrane organisation, protein structure, lipid and polysaccharide composition, conformational variations and molecular interactions. The main challenge in membrane protein studies at the atomic level remains the need for a membrane environment to support their fold. NMR studies in membrane mimetics and membranes of increasing complexity offer close to native environments for structural and molecular studies of membrane proteins. Solution NMR inherits high resolution from small molecule analysis, providing insights from detergent solubilised proteins and small molecular assemblies. Solid-state NMR achieves high resolution in membrane samples through fast sample spinning or sample alignment. Recent developments in dynamic nuclear polarisation NMR allow signal enhancement by orders of magnitude opening new opportunities for expanding the applications of NMR to studies of native membranes and whole cells.
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Affiliation(s)
| | | | - Boyan B. Bonev
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK; (V.Y.); (A.G.)
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13
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Danmaliki GI, Hwang PM. Solution NMR spectroscopy of membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183356. [PMID: 32416193 DOI: 10.1016/j.bbamem.2020.183356] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 05/08/2020] [Accepted: 05/10/2020] [Indexed: 02/06/2023]
Abstract
Integral membrane proteins (IMPs) perform unique and indispensable functions in the cell, making them attractive targets for fundamental research and drug discovery. Developments in protein production, isotope labeling, sample preparation, and pulse sequences have extended the utility of solution NMR spectroscopy for studying IMPs with multiple transmembrane segments. Here we review some recent applications of solution NMR for studying structure, dynamics, and interactions of polytopic IMPs, emphasizing strategies used to overcome common technical challenges.
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Affiliation(s)
- Gaddafi I Danmaliki
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Peter M Hwang
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada; Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
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14
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Bushweller JH. Protein Disulfide Exchange by the Intramembrane Enzymes DsbB, DsbD, and CcdA. J Mol Biol 2020; 432:5091-5103. [PMID: 32305461 DOI: 10.1016/j.jmb.2020.04.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 03/06/2020] [Accepted: 04/08/2020] [Indexed: 12/29/2022]
Abstract
The formation of disulfide bonds in proteins is an essential process in both prokaryotes and eukaryotes. In gram-negative bacteria including Escherichia coli, the proteins DsbA and DsbB mediate the formation of disulfide bonds in the periplasm. DsbA acts as the periplasmic oxidant of periplasmic substrate proteins. DsbA is reoxidized by transfer of reducing equivalents to the 4 TM helix membrane protein DsbB, which transfers reducing equivalents to ubiquinone or menaquinone. Multiple structural studies of DsbB have provided detailed structural information on intermediates in the process of DsbB catalyzed oxidation of DsbA. These structures and the insights gained are described. In proteins with more than one pair of Cys residues, there is the potential for formation of non-native disulfide bonds, making it necessary for the cell to have a mechanism for the isomerization of such non-native disulfide bonds. In E. coli, this is mediated by the proteins DsbC and DsbD. DsbC reduces mis-formed disulfide bonds. The eight-TM-helix protein DsbD reduces DsbC and is itself reduced by cytoplasmic thioredoxin. DsbD also contributes reducing equivalents for the reduction of cytochrome c to facilitate heme attachment. The DsbD functional homolog CcdA is a six-TM-helix membrane protein that provides reducing equivalents for the reduction of cytochrome c. A recent structure determination of CcdA has provided critical insights into how reducing equivalents are transferred across the membrane that likely also provides understanding how this is achieved by DsbD as well. This structure and the insights gained are described.
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Affiliation(s)
- John H Bushweller
- Department of Molecular Physiology and Biological Physics, Department of Chemistry, University of Virginia, Charlottesville, VA 22903, USA.
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15
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Spotlight on the Ballet of Proteins: The Structural Dynamic Properties of Proteins Illuminated by Solution NMR. Int J Mol Sci 2020; 21:ijms21051829. [PMID: 32155847 PMCID: PMC7084655 DOI: 10.3390/ijms21051829] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 03/01/2020] [Accepted: 03/04/2020] [Indexed: 12/22/2022] Open
Abstract
Solution NMR spectroscopy is a unique and powerful technique that has the ability to directly connect the structural dynamics of proteins in physiological conditions to their activity and function. Here, we summarize recent studies in which solution NMR contributed to the discovery of relationships between key dynamic properties of proteins and functional mechanisms in important biological systems. The capacity of NMR to quantify the dynamics of proteins over a range of time scales and to detect lowly populated protein conformations plays a critical role in its power to unveil functional protein dynamics. This analysis of dynamics is not only important for the understanding of biological function, but also in the design of specific ligands for pharmacologically important proteins. Thus, the dynamic view of structure provided by NMR is of importance in both basic and applied biology.
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16
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Christensen S, Halili MA, Strange N, Petit GA, Huston WM, Martin JL, McMahon RM. Oxidoreductase disulfide bond proteins DsbA and DsbB form an active redox pair in Chlamydia trachomatis, a bacterium with disulfide dependent infection and development. PLoS One 2019; 14:e0222595. [PMID: 31536549 PMCID: PMC6752827 DOI: 10.1371/journal.pone.0222595] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 09/02/2019] [Indexed: 12/17/2022] Open
Abstract
Chlamydia trachomatis is an obligate intracellular bacterium with a distinctive biphasic developmental cycle that alternates between two distinct cell types; the extracellular infectious elementary body (EB) and the intracellular replicating reticulate body (RB). Members of the genus Chlamydia are dependent on the formation and degradation of protein disulfide bonds. Moreover, disulfide cross-linking of EB envelope proteins is critical for the infection phase of the developmental cycle. We have identified in C. trachomatis a homologue of the Disulfide Bond forming membrane protein Escherichia coli (E. coli) DsbB (hereafter named CtDsbB) and-using recombinant purified proteins-demonstrated that it is the redox partner of the previously characterised periplasmic oxidase C. trachomatis Disulfide Bond protein A (CtDsbA). CtDsbA protein was detected in C. trachomatis inclusion vacuoles at 20 h post infection, with more detected at 32 and similar levels at 44 h post infection as the developmental cycle proceeds. As a redox pair, CtDsbA and CtDsbB largely resemble their homologous counterparts in E. coli; CtDsbA is directly oxidised by CtDsbB, in a reaction in which both periplasmic cysteine pairs of CtDsbB are required for complete activity. In our hands, this reaction is slow relative to that observed for E. coli equivalents, although this may reflect a non-native expression system and use of a surrogate quinone cofactor. CtDsbA has a second non-catalytic disulfide bond, which has a small stabilising effect on the protein's thermal stability, but which does not appear to influence the interaction of CtDsbA with its partner protein CtDsbB. Expression of CtDsbA during the RB replicative phase and during RB to EB differentiation coincided with the oxidation of the chlamydial outer membrane complex (COMC). Together with our demonstration of an active redox pairing, our findings suggest a potential role for CtDsbA and CtDsbB in the critical disulfide bond formation step in the highly regulated development cycle.
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Affiliation(s)
- Signe Christensen
- Institute for Molecular Bioscience, University of Queensland, St Lucia, Queensland, Australia
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia
| | - Maria A. Halili
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia
| | - Natalie Strange
- School of Life Sciences, University of Technology Sydney, Broadway, New South Wales, Australia
| | - Guillaume A. Petit
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia
| | - Wilhelmina M. Huston
- School of Life Sciences, University of Technology Sydney, Broadway, New South Wales, Australia
| | - Jennifer L. Martin
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia
| | - Róisín M. McMahon
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia
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17
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Solution NMR Spectroscopy for the Determination of Structures of Membrane Proteins in a Lipid Environment. Methods Mol Biol 2019. [PMID: 31218634 DOI: 10.1007/978-1-4939-9512-7_24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/07/2023]
Abstract
NMR spectroscopy has harnessed the recent technical advances to emerge as a competitive, elegant, and eminently viable technique for determining the solution structures of membrane proteins at the level of atomic resolution. Once a good level of cell-based or cell-free expression and purification of a suitably sized membrane protein has been achieved, then NMR offers a combination of several versatile strategies, for example choice of appropriate deuterated or nondeuterated detergents, temperature, and ionic strength; isotope labeling with 2H, 13C, 15N, with or without protonation of Ile (δ1), Leu, and Val methyl protons; combinatorial labeling or unlabeling of specific amino acids; TROSY based-, nonuniform sampling (NUS) based-, and other NMR experiments; measurement of residual dipolar couplings using stretched polyacrylamide gels or DNA nanotubes; spin labeling and paramagnetic relaxation enhancements (PRE). Strategic combinations of these advancements together with availability of highly sensitive cryogenically cooled-probes equipped high-field NMR spectrometers (up to 1 GHz 1H frequency) have allowed the perseverant investigator to successfully overcome several of the conventional pitfalls associated with the NMR technique and membrane proteins, viz., low sensitivity, poor sample stability, spectral crowding, and a limited number of NOEs and other constraints for structure calculations. This has resulted in an unprecedented growth in the number of successfully determined NMR structures of large and complex membrane proteins over the last two decades, and this technique now holds great promise for the structure determination of an ever larger body of membrane proteins.
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Banaś AM, Bocian-Ostrzycka KM, Jagusztyn-Krynicka EK. Engineering of the Dsb (disulfide bond) proteins - contribution towards understanding their mechanism of action and their applications in biotechnology and medicine. Crit Rev Microbiol 2019; 45:433-450. [PMID: 31190593 DOI: 10.1080/1040841x.2019.1622509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The Dsb protein family in prokaryotes catalyzes the generation of disulfide bonds between thiol groups of cysteine residues in nascent proteins, ensuring their proper three-dimensional structure; these bonds are crucial for protein stability and function. The first Dsb protein, Escherichia coli DsbA, was described in 1991. Since then, many details of the bond-formation process have been described through microbiological, biochemical, biophysical and bioinformatics strategies. Research with the model microorganism E. coli and many other bacterial species revealed an enormous diversity of bond-formation mechanisms. Research using Dsb protein engineering has significantly helped to reveal details of the disulfide bond formation. The first part of this review presents the research that led to understanding the mechanism of action of DsbA proteins, which directly transfer their own disulfide into target proteins. The second part concentrates on the mechanism of electron transport through the cell cytoplasmic membrane. Third and lastly, the review discusses the contribution of this research towards new antibacterial agents.
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Affiliation(s)
- Anna Marta Banaś
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw , Miecznikowa 1 , Warsaw , Poland
| | - Katarzyna Marta Bocian-Ostrzycka
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw , Miecznikowa 1 , Warsaw , Poland
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19
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Yazawa K, Furusawa H. Entropy-Driven Mechanisms between Disulfide-Bond Formation Protein A (DsbA) and B (DsbB) in Escherichia coli. ACS OMEGA 2019; 4:8341-8349. [PMID: 31459922 PMCID: PMC6648927 DOI: 10.1021/acsomega.9b00474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 04/30/2019] [Indexed: 06/10/2023]
Abstract
A disulfide-bond formation system for nascent proteins in the Escherichia coli periplasm contains efficient electron transfer systems for the catalysis of oxidation. This electrochemical system has interesting implications in vivo. Disulfide bonds are formed by disulfide-bond formation protein A (DsbA), which contains two reactive cysteines. DsbA is reoxidized by a membrane protein, disulfide-bond formation protein B (DsbB), which has four catalytic cysteines. The oxidation of DsbA by DsbB seems energetically unfavorable on the basis of the redox potential. The oxidizing power of ubiquinone (UQ), which endogenously binds with DsbB, is believed to promote this reaction. However, using UQ-deficient DsbB, it was found that the oxidation of DsbA by DsbB proceeds independently of UQ. Thus, the reaction mechanism of DsbA oxidation by DsbB is under debate. In this study, we used the quartz crystal microbalance technique, which detects the intermediate complex between DsbA and DsbB during DsbA oxidation as a change in mass, to obtain kinetic parameters of DsbA oxidation under both the oxidized and reduced states of UQ at acidic and basic pH. In addition, we utilized sodium dodecyl sulfate polyacrylamide gel electrophoresis mobility shift assay technique to determine the pK a of the cysteine thiol groups in DsbA and DsbB. We found that DsbA oxidation proceeded independently of UQ and was greatly affected in kinetics by the shuffling of electrons among the four cysteine residues in DsbB, regardless of pH. These results suggest that DsbA oxidation is driven in an entropy-dependent manner, in which the electron-delocalized intermediate complex is stabilized by preventing a reverse reaction. These findings could contribute to the design of bio-inspired electrochemical systems for industrial applications.
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Affiliation(s)
- Kenjiro Yazawa
- Division
of Biological and Medical Fibers, Interdisciplinary Cluster for Cutting
Edge Research, Institute for Fiber Engineering, Shinshu University, 3-15-1 Tokida, Ueda City, Nagano 386-8567, Japan
- Department
of Biomolecular Engineering, Tokyo Institute
of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
| | - Hiroyuki Furusawa
- Innovative
Flex Course for Frontier Organic Material Systems (iFront), Graduate
School of Science and Engineering, Yamagata
University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan
- Department
of Biomolecular Engineering, Tokyo Institute
of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
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20
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Lam D, Zhuang J, Cohen LS, Arshava B, Naider FR, Tang M. Effects of chelator lipids, paramagnetic metal ions and trehalose on liposomes by solid-state NMR. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2018; 94:1-6. [PMID: 30096558 DOI: 10.1016/j.ssnmr.2018.07.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 07/25/2018] [Accepted: 07/26/2018] [Indexed: 06/08/2023]
Abstract
The effects of various lipid bound paramagnetic metal ions on liposomes prepared in the presence of trehalose and chelator lipids are evaluated to observe site-specific signal changes on liposome samples with optimal resolution in solid-state NMR spectroscopy. We found that Mn2+, Gd3+ and Dy3+ have different influences on the lipid 13C sites depending on their penetration depths into the bilayer, which can be extracted as distance information. The trehalose-liposome mixture is efficiently packed into solid-state NMR rotors and provides optimal resolution at reasonable instrument temperatures (10-50 °C). The effectiveness and convenience of the trehalose preparation for studying a membrane protein in liposomes are demonstrated by a membrane sample with a model membrane peptide to show that trehalose is useful to prepare consistent and stable membrane protein liposome samples for solid-state NMR.
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Affiliation(s)
- Dennis Lam
- Department of Chemistry, College of Staten Island - Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA
| | - Jianqin Zhuang
- Department of Chemistry, College of Staten Island, Staten Island, NY, 10314, USA
| | - Leah S Cohen
- Department of Chemistry, College of Staten Island, Staten Island, NY, 10314, USA
| | - Boris Arshava
- Department of Chemistry, College of Staten Island, Staten Island, NY, 10314, USA
| | - Fred R Naider
- Department of Chemistry, College of Staten Island - Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA
| | - Ming Tang
- Department of Chemistry, College of Staten Island - Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA.
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21
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Kahler CM, Sarkar-Tyson M, Kibble EA, Stubbs KA, Vrielink A. Enzyme targets for drug design of new anti-virulence therapeutics. Curr Opin Struct Biol 2018; 53:140-150. [PMID: 30223251 DOI: 10.1016/j.sbi.2018.08.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 08/30/2018] [Accepted: 08/30/2018] [Indexed: 12/19/2022]
Abstract
Society has benefitted greatly from the use of antibiotics. Unfortunately, the misuse of these valuable molecules has resulted in increased levels of antibiotic resistance, a major global and public health issue. This resistance and the reliance on a small number of biological targets for the development of antibiotics emphasizes the need for new targets. A critical aspect guiding the development of new antimicrobials through a rational structure-guided approach is to understand the molecular structures of specific biological targets of interest. Here we give an overview of the structures of bacterial virulence enzyme targets involved in protein folding, peptidoglycan biosynthesis and cell wall modification. These include enzymes of the thiol-disulphide oxidoreductase pathway (DSB enzymes), peptidyl-proly cis/trans isomerases (Mips), enzymes from the Mur pathway and enzymes involved in lipopolysaccharide modification (EptA and ArnT). We also present progress towards inhibitor design of these targets for the development of novel anti-virulence therapeutic agents.
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Affiliation(s)
- Charlene M Kahler
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Mitali Sarkar-Tyson
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Emily A Kibble
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Keith A Stubbs
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Alice Vrielink
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia; Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia.
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22
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Engineered Protein Model of the ATP synthase H +- Channel Shows No Salt Bridge at the Rotor-Stator Interface. Sci Rep 2018; 8:11361. [PMID: 30054535 PMCID: PMC6063947 DOI: 10.1038/s41598-018-29693-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 07/17/2018] [Indexed: 12/12/2022] Open
Abstract
ATP synthase is powered by the flow of protons through the molecular turbine composed of two α-helical integral membrane proteins, subunit a, which makes a stator, and a cylindrical rotor assembly made of multiple copies of subunit c. Transient protonation of a universally conserved carboxylate on subunit c (D61 in E. coli) gated by the electrostatic interaction with arginine on subunit a (R210 in E. coli) is believed to be a crucial step in proton transfer across the membrane. We used a fusion protein consisting of subunit a and the adjacent helices of subunit c to test by NMR spectroscopy if cD61 and aR210 are involved in an electrostatic interaction with each other, and found no evidence of such interaction. We have also determined that R140 does not form a salt bridge with either D44 or D124 as was suggested previously by mutation analysis. Our results demonstrate the potential of using arginines as NMR reporter groups for structural and functional studies of challenging membrane proteins.
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23
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Membrane properties that shape the evolution of membrane enzymes. Curr Opin Struct Biol 2018; 51:80-91. [PMID: 29597094 DOI: 10.1016/j.sbi.2018.03.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 03/14/2018] [Accepted: 03/15/2018] [Indexed: 02/07/2023]
Abstract
Spectacular recent progress in structural biology has led to determination of the structures of many integral membrane enzymes that catalyze reactions in which at least one substrate also is membrane bound. A pattern of results seems to be emerging in which the active site chemistry of these enzymes is usually found to be analogous to what is observed for water soluble enzymes catalyzing the same reaction types. However, in light of the chemical, structural, and physical complexity of cellular membranes plus the presence of transmembrane gradients and potentials, these enzymes may be subject to membrane-specific regulatory mechanisms that are only now beginning to be uncovered. We review the membrane-specific environmental traits that shape the evolution of membrane-embedded biocatalysts.
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24
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Zhou Y, Bushweller JH. Solution structure and elevator mechanism of the membrane electron transporter CcdA. Nat Struct Mol Biol 2018; 25:163-169. [PMID: 29379172 PMCID: PMC5805637 DOI: 10.1038/s41594-018-0022-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 12/28/2017] [Indexed: 01/25/2023]
Abstract
Membrane oxidoredutase CcdA plays a central role in supplying reducing equivalents from the bacterial cytoplasm to the envelope. It transports electrons across the membrane using a single pair of cysteines by a mechanism which has not been elucidated. Here we report an NMR structure of the Thermus thermophilus CcdA (TtCcdA) in an oxidized and outward-facing state. CcdA consists of two inverted structural repeats of three transmembrane helices (2 × 3-TM). We computationally modeled and experimentally validated an inward-facing state, which suggests that CcdA uses an elevator-type movement to shuttle the reactive cysteines across the membrane. CcdA belongs to the LysE superfamily. Its structure may be relevant to other LysE clan transporters. Structure comparisons of CcdA, semiSWEET, Pnu, and major facilitator superfamily (MFS) transporters provide insights about membrane transporter architecture and mechanism.
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Affiliation(s)
- Yunpeng Zhou
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA.
| | - John H Bushweller
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA. .,Department of Chemistry, University of Virginia, Charlottesville, VA, USA.
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25
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Koehler Leman J, D'Avino AR, Bhatnagar Y, Gray JJ. Comparison of NMR and crystal structures of membrane proteins and computational refinement to improve model quality. Proteins 2017; 86:57-74. [PMID: 29044728 DOI: 10.1002/prot.25402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 09/27/2017] [Accepted: 10/11/2017] [Indexed: 12/29/2022]
Abstract
Membrane proteins are challenging to study and restraints for structure determination are typically sparse or of low resolution because the membrane environment that surrounds them leads to a variety of experimental challenges. When membrane protein structures are determined by different techniques in different environments, a natural question is "which structure is most biologically relevant?" Towards answering this question, we compiled a dataset of membrane proteins with known structures determined by both solution NMR and X-ray crystallography. By investigating differences between the structures, we found that RMSDs between crystal and NMR structures are below 5 Å in the membrane region, NMR ensembles have a higher convergence in the membrane region, crystal structures typically have a straighter transmembrane region, have higher stereo-chemical correctness, and are more tightly packed. After quantifying these differences, we used high-resolution refinement of the NMR structures to mitigate them, which paves the way for identifying and improving the structural quality of membrane proteins.
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Affiliation(s)
- Julia Koehler Leman
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland.,Center for Computational Biology, Flatiron Institute, Simons Foundation, New York, New York
| | - Andrew R D'Avino
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland.,Department of Biology, Johns Hopkins University, Baltimore, Maryland
| | - Yash Bhatnagar
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Jeffrey J Gray
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland
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26
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Li S, Shen G, Li W. Intramembrane Thiol Oxidoreductases: Evolutionary Convergence and Structural Controversy. Biochemistry 2017; 57:258-266. [PMID: 29064673 DOI: 10.1021/acs.biochem.7b00876] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
During oxidative protein folding, disulfide bond formation is catalyzed by thiol oxidoreductases. Through dedicated relay pathways, the disulfide is generated in donor enzymes, passed to carrier enzymes, and subsequently delivered to target proteins. The eukaryotic disulfide donors are flavoenzymes, Ero1 in the endoplasmic reticulum and Erv1 in mitochondria. In prokaryotes, disulfide generation is coupled to quinone reduction, catalyzed by intramembrane donor enzymes, DsbB and VKOR. To catalyze de novo disulfide formation, these different disulfide donors show striking structural convergence at several levels. They share a four-helix bundle core structure at their active site, which contains a CXXC motif at a helical end. They have also evolved a flexible loop with shuttle cysteines to transfer electrons to the active site and relay the disulfide bond to the carrier enzymes. Studies of the prokaryotic VKOR, however, have stirred debate about whether the human homologue adopts the same topology with four transmembrane helices and uses the same electron-transfer mechanism. The controversies have recently been resolved by investigating the human VKOR structure and catalytic process in living cells with a mass spectrometry-based approach. Structural convergence between human VKOR and the disulfide donors is found to underlie cofactor reduction, disulfide generation, and electron transfer.
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Affiliation(s)
- Shuang Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine , St. Louis, Missouri 63110, United States
| | - Guomin Shen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine , St. Louis, Missouri 63110, United States.,College of Medicine, Henan University of Science and Technology , Luoyang, Henan 471003, P. R. China
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine , St. Louis, Missouri 63110, United States
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27
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Sim DW, Lu Z, Won HS, Lee SN, Seo MD, Lee BJ, Kim JH. Application of Solution NMR to Structural Studies on α-Helical Integral Membrane Proteins. Molecules 2017; 22:molecules22081347. [PMID: 28809779 PMCID: PMC6152068 DOI: 10.3390/molecules22081347] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 08/10/2017] [Accepted: 08/12/2017] [Indexed: 02/05/2023] Open
Abstract
A large portion of proteins in living organisms are membrane proteins which play critical roles in the biology of the cell, from maintenance of the biological membrane integrity to communication of cells with their surroundings. To understand their mechanism of action, structural information is essential. Nevertheless, structure determination of transmembrane proteins is still a challenging area, even though recently the number of deposited structures of membrane proteins in the PDB has rapidly increased thanks to the efforts using X-ray crystallography, electron microscopy, and solid and solution nuclear magnetic resonance (NMR) technology. Among these technologies, solution NMR is a powerful tool for studying protein-protein, protein-ligand interactions and protein dynamics at a wide range of time scales as well as structure determination of membrane proteins. This review provides general and useful guideline for membrane protein sample preparation and the choice of membrane-mimetic media, which are the key step for successful structural analysis. Furthermore, this review provides an opportunity to look at recent applications of solution NMR to structural studies on α-helical membrane proteins through some success stories.
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Affiliation(s)
- Dae-Won Sim
- Department of Biotechnology, College of Biomedical and Health Science, Konkuk University, Chungbuk 27478, Korea.
| | - Zhenwei Lu
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37204, USA.
| | - Hyung-Sik Won
- Department of Biotechnology, College of Biomedical and Health Science, Konkuk University, Chungbuk 27478, Korea.
| | - Seu-Na Lee
- Department of Biotechnology, College of Biomedical and Health Science, Konkuk University, Chungbuk 27478, Korea.
| | - Min-Duk Seo
- Department of Molecular Science and Technology & College of Pharmacy, Ajou University, Suwon 16499, Korea.
| | - Bong-Jin Lee
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 151-742, Korea.
| | - Ji-Hun Kim
- College of Pharmacy, Chungbuk National University, Cheongju 28160, Chungbuk, Korea.
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28
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Harris NJ, Reading E, Ataka K, Grzegorzewski L, Charalambous K, Liu X, Schlesinger R, Heberle J, Booth PJ. Structure formation during translocon-unassisted co-translational membrane protein folding. Sci Rep 2017; 7:8021. [PMID: 28808343 PMCID: PMC5556060 DOI: 10.1038/s41598-017-08522-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 07/10/2017] [Indexed: 01/16/2023] Open
Abstract
Correctly folded membrane proteins underlie a plethora of cellular processes, but little is known about how they fold. Knowledge of folding mechanisms centres on reversible folding of chemically denatured membrane proteins. However, this cannot replicate the unidirectional elongation of the protein chain during co-translational folding in the cell, where insertion is assisted by translocase apparatus. We show that a lipid membrane (devoid of translocase components) is sufficient for successful co-translational folding of two bacterial α-helical membrane proteins, DsbB and GlpG. Folding is spontaneous, thermodynamically driven, and the yield depends on lipid composition. Time-resolving structure formation during co-translational folding revealed different secondary and tertiary structure folding pathways for GlpG and DsbB that correlated with membrane interfacial and biological transmembrane amino acid hydrophobicity scales. Attempts to refold DsbB and GlpG from chemically denatured states into lipid membranes resulted in extensive aggregation. Co-translational insertion and folding is thus spontaneous and minimises aggregation whilst maximising correct folding.
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Affiliation(s)
- Nicola J Harris
- Department of Chemistry, Britannia House, 7 Trinity Street, King's College London, London, UK
| | - Eamonn Reading
- Department of Chemistry, Britannia House, 7 Trinity Street, King's College London, London, UK
| | - Kenichi Ataka
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Dahlem, Germany
| | - Lucjan Grzegorzewski
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Dahlem, Germany
| | - Kalypso Charalambous
- Department of Chemistry, Britannia House, 7 Trinity Street, King's College London, London, UK
| | - Xia Liu
- School of Biochemistry, Medical Sciences, University Walk, University of Bristol, Bristol, UK
| | - Ramona Schlesinger
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Dahlem, Germany
| | - Joachim Heberle
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Dahlem, Germany
| | - Paula J Booth
- Department of Chemistry, Britannia House, 7 Trinity Street, King's College London, London, UK.
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29
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Abstract
Cysteine thiols are among the most reactive functional groups in proteins, and their pairing in disulfide linkages is a common post-translational modification in proteins entering the secretory pathway. This modest amino acid alteration, the mere removal of a pair of hydrogen atoms from juxtaposed cysteine residues, contrasts with the substantial changes that characterize most other post-translational reactions. However, the wide variety of proteins that contain disulfides, the profound impact of cross-linking on the behavior of the protein polymer, the numerous and diverse players in intracellular pathways for disulfide formation, and the distinct biological settings in which disulfide bond formation can take place belie the simplicity of the process. Here we lay the groundwork for appreciating the mechanisms and consequences of disulfide bond formation in vivo by reviewing chemical principles underlying cysteine pairing and oxidation. We then show how enzymes tune redox-active cofactors and recruit oxidants to improve the specificity and efficiency of disulfide formation. Finally, we discuss disulfide bond formation in a cellular context and identify important principles that contribute to productive thiol oxidation in complex, crowded, dynamic environments.
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Affiliation(s)
- Deborah Fass
- Department of Structural Biology, Weizmann Institute of Science , Rehovot 7610001, Israel
| | - Colin Thorpe
- Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716, United States
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30
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NMR as a tool to investigate the structure, dynamics and function of membrane proteins. Nat Struct Mol Biol 2017; 23:468-74. [PMID: 27273629 DOI: 10.1038/nsmb.3226] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 04/12/2016] [Indexed: 12/29/2022]
Abstract
Membrane-protein NMR occupies a unique niche for determining structures, assessing dynamics, examining folding, and studying the binding of lipids, ligands and drugs to membrane proteins. However, NMR analyses of membrane proteins also face special challenges that are not encountered with soluble proteins, including sample preparation, size limitation, spectral crowding and sparse data accumulation. This Perspective provides a snapshot of current achievements, future opportunities and possible limitations in this rapidly developing field.
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31
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Applications of NMR to membrane proteins. Arch Biochem Biophys 2017; 628:92-101. [PMID: 28529197 DOI: 10.1016/j.abb.2017.05.011] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 05/15/2017] [Accepted: 05/17/2017] [Indexed: 01/14/2023]
Abstract
Membrane proteins present a challenge for structural biology. In this article, we review some of the recent developments that advance the application of NMR to membrane proteins, with emphasis on structural studies in detergent-free, lipid bilayer samples that resemble the native environment. NMR spectroscopy is not only ideally suited for structure determination of membrane proteins in hydrated lipid bilayer membranes, but also highly complementary to the other principal techniques based on X-ray and electron diffraction. Recent advances in NMR instrumentation, spectroscopic methods, computational methods, and sample preparations are driving exciting new efforts in membrane protein structural biology.
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32
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Bacterial thiol oxidoreductases - from basic research to new antibacterial strategies. Appl Microbiol Biotechnol 2017; 101:3977-3989. [PMID: 28409380 PMCID: PMC5403849 DOI: 10.1007/s00253-017-8291-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 04/03/2017] [Accepted: 04/04/2017] [Indexed: 12/15/2022]
Abstract
The recent, rapid increase in bacterial antimicrobial resistance has become a major public health concern. One approach to generate new classes of antibacterials is targeting virulence rather than the viability of bacteria. Proteins of the Dsb system, which play a key role in the virulence of many pathogenic microorganisms, represent potential new drug targets. The first part of the article presents current knowledge of how the Dsb system impacts function of various protein secretion systems that influence the virulence of many pathogenic bacteria. Next, the review describes methods used to study the structure, biochemistry, and microbiology of the Dsb proteins and shows how these experiments broaden our knowledge about their function. The lessons gained from basic research have led to a specific search for inhibitors blocking the Dsb networks.
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33
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Reichel K, Fisette O, Braun T, Lange OF, Hummer G, Schäfer LV. Systematic evaluation of CS-Rosetta for membrane protein structure prediction with sparse NOE restraints. Proteins 2017; 85:812-826. [PMID: 27936510 DOI: 10.1002/prot.25224] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 10/25/2016] [Accepted: 11/23/2016] [Indexed: 11/06/2022]
Abstract
We critically test and validate the CS-Rosetta methodology for de novo structure prediction of α-helical membrane proteins (MPs) from NMR data, such as chemical shifts and NOE distance restraints. By systematically reducing the number and types of NOE restraints, we focus on determining the regime in which MP structures can be reliably predicted and pinpoint the boundaries of the approach. Five MPs of known structure were used as test systems, phototaxis sensory rhodopsin II (pSRII), a subdomain of pSRII, disulfide binding protein B (DsbB), microsomal prostaglandin E2 synthase-1 (mPGES-1), and translocator protein (TSPO). For pSRII and DsbB, where NMR and X-ray structures are available, resolution-adapted structural recombination (RASREC) CS-Rosetta yields structures that are as close to the X-ray structure as the published NMR structures if all available NMR data are used to guide structure prediction. For mPGES-1 and Bacillus cereus TSPO, where only X-ray crystal structures are available, highly accurate structures are obtained using simulated NMR data. One main advantage of RASREC CS-Rosetta is its robustness with respect to even a drastic reduction of the number of NOEs. Close-to-native structures were obtained with one randomly picked long-range NOEs for every 14, 31, 38, and 8 residues for full-length pSRII, the pSRII subdomain, TSPO, and DsbB, respectively, in addition to using chemical shifts. For mPGES-1, atomically accurate structures could be predicted even from chemical shifts alone. Our results show that atomic level accuracy for helical membrane proteins is achievable with CS-Rosetta using very sparse NOE restraint sets to guide structure prediction. Proteins 2017; 85:812-826. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Katrin Reichel
- Center for Theoretical Chemistry, Ruhr-University Bochum, Bochum, 44780, Germany.,Max Planck Institute of Biophysics, 60438, Frankfurt am Main, Germany
| | - Olivier Fisette
- Center for Theoretical Chemistry, Ruhr-University Bochum, Bochum, 44780, Germany
| | - Tatjana Braun
- ICS-6 Structural Biochemistry, Institute of Complex Systems, Forschungszentrum Jülich, Jülich, 52425, Germany
| | - Oliver F Lange
- Biomolecular NMR and Munich Center for Integrated Protein Science, Department Chemie, Technische Universität München, Garching, 85747, Germany
| | - Gerhard Hummer
- Max Planck Institute of Biophysics, 60438, Frankfurt am Main, Germany.,Institute of Biophysics, Goethe University, 60438, Frankfurt am Main, Germany
| | - Lars V Schäfer
- Center for Theoretical Chemistry, Ruhr-University Bochum, Bochum, 44780, Germany
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34
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Kroncke BM, Duran AM, Mendenhall JL, Meiler J, Blume JD, Sanders CR. Documentation of an Imperative To Improve Methods for Predicting Membrane Protein Stability. Biochemistry 2016; 55:5002-9. [PMID: 27564391 PMCID: PMC5024705 DOI: 10.1021/acs.biochem.6b00537] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
![]()
There
is a compelling and growing need to accurately predict the
impact of amino acid mutations on protein stability for problems in
personalized medicine and other applications. Here the ability of
10 computational tools to accurately predict mutation-induced perturbation
of folding stability (ΔΔG) for membrane
proteins of known structure was assessed. All methods for predicting
ΔΔG values performed significantly worse
when applied to membrane proteins than when applied to soluble proteins,
yielding estimated concordance, Pearson, and Spearman correlation
coefficients of <0.4 for membrane proteins. Rosetta and PROVEAN
showed a modest ability to classify mutations as destabilizing (ΔΔG < −0.5 kcal/mol), with a 7 in 10 chance of correctly
discriminating a randomly chosen destabilizing variant from a randomly
chosen stabilizing variant. However, even this performance is significantly
worse than for soluble proteins. This study highlights the need for
further development of reliable and reproducible methods for predicting
thermodynamic folding stability in membrane proteins.
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Affiliation(s)
- Brett M Kroncke
- Department of Biochemistry, ‡Center for Structural Biology, §Departments of Chemistry, Pharmacology, and Bioinformatics, and ∥Department of Biostatistics, Vanderbilt University , Nashville, Tennessee 37240, United States
| | - Amanda M Duran
- Department of Biochemistry, ‡Center for Structural Biology, §Departments of Chemistry, Pharmacology, and Bioinformatics, and ∥Department of Biostatistics, Vanderbilt University , Nashville, Tennessee 37240, United States
| | - Jeffrey L Mendenhall
- Department of Biochemistry, ‡Center for Structural Biology, §Departments of Chemistry, Pharmacology, and Bioinformatics, and ∥Department of Biostatistics, Vanderbilt University , Nashville, Tennessee 37240, United States
| | - Jens Meiler
- Department of Biochemistry, ‡Center for Structural Biology, §Departments of Chemistry, Pharmacology, and Bioinformatics, and ∥Department of Biostatistics, Vanderbilt University , Nashville, Tennessee 37240, United States
| | - Jeffrey D Blume
- Department of Biochemistry, ‡Center for Structural Biology, §Departments of Chemistry, Pharmacology, and Bioinformatics, and ∥Department of Biostatistics, Vanderbilt University , Nashville, Tennessee 37240, United States
| | - Charles R Sanders
- Department of Biochemistry, ‡Center for Structural Biology, §Departments of Chemistry, Pharmacology, and Bioinformatics, and ∥Department of Biostatistics, Vanderbilt University , Nashville, Tennessee 37240, United States
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35
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Abstract
AbstractIncreasing evidence suggests that most proteins occur and function in complexes rather than as isolated entities when embedded in cellular membranes. Nuclear magnetic resonance (NMR) provides increasing possibilities to study structure, dynamics and assembly of such systems. In our review, we discuss recent methodological progress to study membrane–protein complexes (MPCs) by NMR, starting with expression, isotope-labeling and reconstitution protocols. We review approaches to deal with spectral complexity and limited spectral spectroscopic sensitivity that are usually encountered in NMR-based studies of MPCs. We highlight NMR applications in various classes of MPCs, including G-protein-coupled receptors, ion channels and retinal proteins and extend our discussion to protein–protein complexes that span entire cellular compartments or orchestrate processes such as protein transport across or within membranes. These examples demonstrate the growing potential of NMR-based studies of MPCs to provide critical insight into the energetics of protein–ligand and protein–protein interactions that underlie essential biological functions in cellular membranes.
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36
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Oxenoid K, Chou JJ. A functional NMR for membrane proteins: dynamics, ligand binding, and allosteric modulation. Protein Sci 2016; 25:959-73. [PMID: 26928605 DOI: 10.1002/pro.2910] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 02/25/2016] [Accepted: 02/25/2016] [Indexed: 01/13/2023]
Abstract
By nature of conducting ions, transporting substrates and transducing signals, membrane channels, transporters and receptors are expected to exhibit intrinsic conformational dynamics. It is therefore of great interest and importance to understand the various properties of conformational dynamics acquired by these proteins, for example, the relative population of states, exchange rate, conformations of multiple states, and how small molecule ligands modulate the conformational exchange. Because small molecule binding to membrane proteins can be weak and/or dynamic, structural characterization of these effects is very challenging. This review describes several NMR studies of membrane protein dynamics, ligand-induced conformational rearrangements, and the effect of ligand binding on the equilibrium of conformational exchange. The functional significance of the observed phenomena is discussed.
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Affiliation(s)
- Kirill Oxenoid
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, 02115
| | - James J Chou
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, 02115
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37
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Hiruma-Shimizu K, Shimizu H, Thompson GS, Kalverda AP, Patching SG. Deuterated detergents for structural and functional studies of membrane proteins: Properties, chemical synthesis and applications. Mol Membr Biol 2016; 32:139-55. [DOI: 10.3109/09687688.2015.1125536] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
| | - Hiroki Shimizu
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Hokkaido, Japan,
| | - Gary S. Thompson
- School of Molecular and Cellular Biology, University of Leeds, Leeds, UK,
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK, and
| | - Arnout P. Kalverda
- School of Molecular and Cellular Biology, University of Leeds, Leeds, UK,
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK, and
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38
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The membrane topology of vitamin K epoxide reductase is conserved between human isoforms and the bacterial enzyme. Biochem J 2016; 473:851-8. [PMID: 26772871 DOI: 10.1042/bj20151223] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 01/15/2016] [Indexed: 11/17/2022]
Abstract
The membrane topology of vitamin K epoxide reductase (VKOR) is controversial with data supporting both a three transmembrane and a four transmembrane model. The positioning of the transmembrane domains and the loops between these domains is critical if we are to understand the mechanism of vitamin K oxidation and its recycling by members of the thioredoxin family of proteins and the mechanism of action of warfarin, an inhibitor of VKOR. Here we show that both mammalian VKOR isoforms adopt the same topology, with the large loop between transmembrane one and two facing the lumen of the endoplasmic reticulum (ER). We used a redox sensitive green fluorescent protein (GFP) fused to the N- or C-terminus to show that these regions face the cytosol, and introduction of glycosylation sites along with mixed disulfide formation with thioredoxin-like transmembrane protein (TMX) to demonstrate ER localization of the major loop. The topology is identical with the bacterial homologue from Synechococcussp., for which the structure and mechanism of recycling has been characterized. Our results provide a resolution to the membrane topology controversy and support previous results suggesting a role for members of the ER protein disulfide isomerase (PDI) family in recycling VKOR.
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39
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NMR of Membrane Proteins: Beyond Crystals. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 922:29-42. [DOI: 10.1007/978-3-319-35072-1_3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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40
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Liu S, Cheng W, Fowle Grider R, Shen G, Li W. Structures of an intramembrane vitamin K epoxide reductase homolog reveal control mechanisms for electron transfer. Nat Commun 2015; 5:3110. [PMID: 24477003 PMCID: PMC4360977 DOI: 10.1038/ncomms4110] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 12/13/2013] [Indexed: 01/19/2023] Open
Abstract
The intramembrane vitamin K epoxide reductase (VKOR) supports blood coagulation in humans and is the target of the anticoagulant warfarin. VKOR and its homologs generate disulfide bonds in organisms ranging from bacteria to humans. Here, to better understand the mechanism of VKOR catalysis, we report two crystal structures of a bacterial VKOR captured in different reaction states. These structures reveal a short helix at the hydrophobic active site of VKOR that alters between wound and unwound conformations. Motions of this “horizontal helix” promote electron transfer by regulating the positions of two cysteines in an adjacent loop. Winding of the helix separates these “loop cysteines” to prevent backward electron flow. Despite these motions, hydrophobicity at the active site is maintained to facilitate VKOR catalysis. Biochemical experiments suggest that several warfarin-resistant mutations act by changing the conformation of the horizontal helix. Taken together, these studies provide a comprehensive understanding of VKOR function.
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Affiliation(s)
- Shixuan Liu
- 1] Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, Missouri 63110, USA [2]
| | - Wei Cheng
- 1] Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, Missouri 63110, USA [2]
| | - Ronald Fowle Grider
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, Missouri 63110, USA
| | - Guomin Shen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, Missouri 63110, USA
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, Missouri 63110, USA
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41
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Bevans CG, Krettler C, Reinhart C, Watzka M, Oldenburg J. Phylogeny of the Vitamin K 2,3-Epoxide Reductase (VKOR) Family and Evolutionary Relationship to the Disulfide Bond Formation Protein B (DsbB) Family. Nutrients 2015; 7:6224-49. [PMID: 26230708 PMCID: PMC4555120 DOI: 10.3390/nu7085281] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 06/25/2015] [Accepted: 07/09/2015] [Indexed: 12/04/2022] Open
Abstract
In humans and other vertebrate animals, vitamin K 2,3-epoxide reductase (VKOR) family enzymes are the gatekeepers between nutritionally acquired K vitamins and the vitamin K cycle responsible for posttranslational modifications that confer biological activity upon vitamin K-dependent proteins with crucial roles in hemostasis, bone development and homeostasis, hormonal carbohydrate regulation and fertility. We report a phylogenetic analysis of the VKOR family that identifies five major clades. Combined phylogenetic and site-specific conservation analyses point to clade-specific similarities and differences in structure and function. We discovered a single-site determinant uniquely identifying VKOR homologs belonging to human pathogenic, obligate intracellular prokaryotes and protists. Building on previous work by Sevier et al. (Protein Science 14:1630), we analyzed structural data from both VKOR and prokaryotic disulfide bond formation protein B (DsbB) families and hypothesize an ancient evolutionary relationship between the two families where one family arose from the other through a gene duplication/deletion event. This has resulted in circular permutation of primary sequence threading through the four-helical bundle protein folds of both families. This is the first report of circular permutation relating distant α-helical membrane protein sequences and folds. In conclusion, we suggest a chronology for the evolution of the five extant VKOR clades.
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Affiliation(s)
| | - Christoph Krettler
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, 60388 Frankfurt am Main, Germany.
| | - Christoph Reinhart
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, 60388 Frankfurt am Main, Germany.
| | - Matthias Watzka
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, 53105 Bonn, Germany.
| | - Johannes Oldenburg
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, 53105 Bonn, Germany.
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42
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Lo RH, Kroncke BM, Solomon TL, Columbus L. Mapping membrane protein backbone dynamics: a comparison of site-directed spin labeling with NMR 15N-relaxation measurements. Biophys J 2015; 107:1697-702. [PMID: 25296323 DOI: 10.1016/j.bpj.2014.08.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 08/15/2014] [Accepted: 08/19/2014] [Indexed: 11/26/2022] Open
Abstract
The ability to detect nanosecond backbone dynamics with site-directed spin labeling (SDSL) in soluble proteins has been well established. However, for membrane proteins, the nitroxide appears to have more interactions with the protein surface, potentially hindering the sensitivity to backbone motions. To determine whether membrane protein backbone dynamics could be mapped with SDSL, a nitroxide was introduced at 55 independent sites in a model polytopic membrane protein, TM0026. Electron paramagnetic resonance spectral parameters were compared with NMR (15)N-relaxation data. Sequential scans revealed backbone dynamics with the same trends observed for the R1 relaxation rate, suggesting that nitroxide dynamics remain coupled to the backbone on membrane proteins.
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Affiliation(s)
- Ryan H Lo
- Department of Chemistry, University of Virginia, Charlottesville, Virginia
| | - Brett M Kroncke
- Department of Chemistry, University of Virginia, Charlottesville, Virginia
| | - Tsega L Solomon
- Department of Chemistry, University of Virginia, Charlottesville, Virginia
| | - Linda Columbus
- Department of Chemistry, University of Virginia, Charlottesville, Virginia.
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43
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Brown LS, Ladizhansky V. Membrane proteins in their native habitat as seen by solid-state NMR spectroscopy. Protein Sci 2015; 24:1333-46. [PMID: 25973959 DOI: 10.1002/pro.2700] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 04/07/2015] [Accepted: 04/09/2015] [Indexed: 12/21/2022]
Abstract
Membrane proteins play many critical roles in cells, mediating flow of material and information across cell membranes. They have evolved to perform these functions in the environment of a cell membrane, whose physicochemical properties are often different from those of common cell membrane mimetics used for structure determination. As a result, membrane proteins are difficult to study by traditional methods of structural biology, and they are significantly underrepresented in the protein structure databank. Solid-state Nuclear Magnetic Resonance (SSNMR) has long been considered as an attractive alternative because it allows for studies of membrane proteins in both native-like membranes composed of synthetic lipids and in cell membranes. Over the past decade, SSNMR has been rapidly developing into a major structural method, and a growing number of membrane protein structures obtained by this technique highlights its potential. Here we discuss membrane protein sample requirements, review recent progress in SSNMR methodologies, and describe recent advances in characterizing membrane proteins in the environment of a cellular membrane.
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Affiliation(s)
- Leonid S Brown
- Department of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - Vladimir Ladizhansky
- Department of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
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44
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Szarka A, Bánhegyi G. Oxidative folding: recent developments. Biomol Concepts 2015; 2:379-90. [PMID: 25962043 DOI: 10.1515/bmc.2011.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 07/21/2011] [Indexed: 01/29/2023] Open
Abstract
Disulfide bond formation in proteins is an effective tool of both structure stabilization and redox regulation. The prokaryotic periplasm and the endoplasmic reticulum of eukaryotes were long considered as the only compartments for enzyme mediated formation of stable disulfide bonds. Recently, the mitochondrial intermembrane space has emerged as the third protein-oxidizing compartment. The classic view on the mechanism of oxidative folding in the endoplasmic reticulum has also been reshaped by new observations. Moreover, besides the structure stabilizing function, reversible disulfide bridge formation in some proteins of the endoplasmic reticulum, seems to play a regulatory role. This review briefly summarizes the present knowledge of the redox systems supporting oxidative folding, emphasizing recent developments.
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45
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Ding Y, Fujimoto LM, Yao Y, Marassi FM. Solid-state NMR of the Yersinia pestis outer membrane protein Ail in lipid bilayer nanodiscs sedimented by ultracentrifugation. JOURNAL OF BIOMOLECULAR NMR 2015; 61:275-86. [PMID: 25578899 PMCID: PMC4398618 DOI: 10.1007/s10858-014-9893-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 12/20/2014] [Indexed: 05/22/2023]
Abstract
Solid-state NMR studies of sedimented soluble proteins has been developed recently as an attractive approach for overcoming the size limitations of solution NMR spectroscopy while bypassing the need for sample crystallization or precipitation (Bertini et al. Proc Natl Acad Sci USA 108(26):10396-10399, 2011). Inspired by the potential benefits of this method, we have investigated the ability to sediment lipid bilayer nanodiscs reconstituted with a membrane protein. In this study, we show that nanodiscs containing the outer membrane protein Ail from Yersinia pestis can be sedimented for solid-state NMR structural studies, without the need for precipitation or lyophilization. Optimized preparations of Ail in phospholipid nanodiscs support both the structure and the fibronectin binding activity of the protein. The same sample can be used for solution NMR, solid-state NMR and activity assays, facilitating structure-activity correlation experiments across a wide range of timescales.
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Affiliation(s)
- Yi Ding
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla CA 92037, USA
| | - L. Miya Fujimoto
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla CA 92037, USA
| | - Yong Yao
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla CA 92037, USA
| | - Francesca M. Marassi
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla CA 92037, USA
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla CA 92037, USA. [Tel: 858-795-5282; Mail: ]
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46
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Affiliation(s)
- Rob Kaptein
- Bijvoet Centre, Utrecht University, 3584 CH, Utrecht, The Netherlands
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Solution NMR Structure Determination of Polytopic α-Helical Membrane Proteins: A Guide to Spin Label Paramagnetic Relaxation Enhancement Restraints. Methods Enzymol 2015; 557:329-48. [PMID: 25950972 DOI: 10.1016/bs.mie.2014.12.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Solution nuclear magnetic resonance structures of polytopic α-helical membrane proteins require additional restraints beyond the traditional Nuclear Overhauser Effect (NOE) restraints. Several methods have been developed and this review focuses on paramagnetic relaxation enhancement (PRE). Important aspects of spin labeling, PRE measurements, structure calculations, and structural quality are discussed.
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Patil NA, Tailhades J, Hughes RA, Separovic F, Wade JD, Hossain MA. Cellular disulfide bond formation in bioactive peptides and proteins. Int J Mol Sci 2015; 16:1791-805. [PMID: 25594871 PMCID: PMC4307334 DOI: 10.3390/ijms16011791] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 01/02/2015] [Indexed: 11/16/2022] Open
Abstract
Bioactive peptides play important roles in metabolic regulation and modulation and many are used as therapeutics. These peptides often possess disulfide bonds, which are important for their structure, function and stability. A systematic network of enzymes--a disulfide bond generating enzyme, a disulfide bond donor enzyme and a redox cofactor--that function inside the cell dictates the formation and maintenance of disulfide bonds. The main pathways that catalyze disulfide bond formation in peptides and proteins in prokaryotes and eukaryotes are remarkably similar and share several mechanistic features. This review summarizes the formation of disulfide bonds in peptides and proteins by cellular and recombinant machinery.
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Affiliation(s)
- Nitin A Patil
- Florey Institute of Neuroscience and Mental Health, the University of Melbourne, Victoria 3010, Australia.
| | - Julien Tailhades
- Florey Institute of Neuroscience and Mental Health, the University of Melbourne, Victoria 3010, Australia.
| | - Richard Anthony Hughes
- Department of Pharmacology and Therapeutics, the University of Melbourne, Victoria 3010, Australia.
| | - Frances Separovic
- School of Chemistry, the University of Melbourne, Victoria 3010, Australia.
| | - John D Wade
- Florey Institute of Neuroscience and Mental Health, the University of Melbourne, Victoria 3010, Australia.
| | - Mohammed Akhter Hossain
- Florey Institute of Neuroscience and Mental Health, the University of Melbourne, Victoria 3010, Australia.
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Furuita K, Kataoka S, Sugiki T, Hattori Y, Kobayashi N, Ikegami T, Shiozaki K, Fujiwara T, Kojima C. Utilization of paramagnetic relaxation enhancements for high-resolution NMR structure determination of a soluble loop-rich protein with sparse NOE distance restraints. JOURNAL OF BIOMOLECULAR NMR 2015; 61:55-64. [PMID: 25428765 DOI: 10.1007/s10858-014-9882-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2014] [Accepted: 11/19/2014] [Indexed: 06/04/2023]
Abstract
NMR structure determination of soluble proteins depends in large part on distance restraints derived from NOE. In this study, we examined the impact of paramagnetic relaxation enhancement (PRE)-derived distance restraints on protein structure determination. A high-resolution structure of the loop-rich soluble protein Sin1 could not be determined by conventional NOE-based procedures due to an insufficient number of NOE restraints. By using the 867 PRE-derived distance restraints obtained from the NOE-based structure determination procedure, a high-resolution structure of Sin1 could be successfully determined. The convergence and accuracy of the determined structure were improved by increasing the number of PRE-derived distance restraints. This study demonstrates that PRE-derived distance restraints are useful in the determination of a high-resolution structure of a soluble protein when the number of NOE constraints is insufficient.
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Affiliation(s)
- Kyoko Furuita
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
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Hiruma-Shimizu K, Kalverda AP, Henderson PJF, Homans SW, Patching SG. Synthesis of uniformly deuteratedn-dodecyl-β-d-maltoside (d39-DDM) for solubilization of membrane proteins in TROSY NMR experiments. J Labelled Comp Radiopharm 2014; 57:737-43. [DOI: 10.1002/jlcr.3249] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Revised: 10/21/2014] [Accepted: 11/06/2014] [Indexed: 01/07/2023]
Affiliation(s)
- Kazumi Hiruma-Shimizu
- School of Molecular and Cellular Biology; University of Leeds; Leeds UK
- Astbury Centre for Structural Molecular Biology; University of Leeds; Leeds UK
- Waseda University; Tokyo Japan
| | - Arnout P. Kalverda
- School of Molecular and Cellular Biology; University of Leeds; Leeds UK
- Astbury Centre for Structural Molecular Biology; University of Leeds; Leeds UK
| | - Peter J. F. Henderson
- School of Biomedical Sciences; University of Leeds; Leeds UK
- Astbury Centre for Structural Molecular Biology; University of Leeds; Leeds UK
| | - Steve W. Homans
- School of Molecular and Cellular Biology; University of Leeds; Leeds UK
- Astbury Centre for Structural Molecular Biology; University of Leeds; Leeds UK
- Newcastle University; Newcastle UK
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