1
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Imran A, Moyer BS, Kalina D, Duncan TM, Moody KJ, Wolfe AJ, Cosgrove MS, Movileanu L. Convergent Alterations of a Protein Hub Produce Divergent Effects within a Binding Site. ACS Chem Biol 2022; 17:1586-1597. [PMID: 35613319 PMCID: PMC9207812 DOI: 10.1021/acschembio.2c00273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Progress in tumor
sequencing and cancer databases has created an
enormous amount of information that scientists struggle to sift through.
While several research groups have created computational methods to
analyze these databases, much work still remains in distinguishing
key implications of pathogenic mutations. Here, we describe an approach
to identify and evaluate somatic cancer mutations of WD40 repeat protein
5 (WDR5), a chromatin-associated protein hub. This multitasking protein
maintains the functional integrity of large multi-subunit enzymatic
complexes of the six human SET1 methyltransferases. Remarkably, the
somatic cancer mutations of WDR5 preferentially distribute within
and around an essential cavity, which hosts the WDR5 interaction (Win)
binding site. Hence, we assessed the real-time binding kinetics of
the interactions of key clustered WDR5 mutants with the Win motif
peptide ligands of the SET1 family members (SET1Win). Our
measurements highlight that this subset of mutants exhibits divergent
perturbations in the kinetics and strength of interactions not only
relative to those of the native WDR5 but also among various SET1Win ligands. These outcomes could form a fundamental basis
for future drug discovery and other developments in medical biotechnology.
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Affiliation(s)
- Ali Imran
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, United States
| | - Brandon S. Moyer
- Ichor Life Sciences, Inc., 2651 US Route 11, LaFayette, New York 13084, United States
| | - Dan Kalina
- Ichor Life Sciences, Inc., 2651 US Route 11, LaFayette, New York 13084, United States
- Department of Chemistry, State University of New York College of Environmental Science and Forestry, 1 Forestry Dr., Syracuse, New York 13210, United States
| | - Thomas M. Duncan
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, 4249 Weiskotten Hall, 766 Irving Avenue, Syracuse, New York 13210, United States
| | - Kelsey J. Moody
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, United States
- Ichor Life Sciences, Inc., 2651 US Route 11, LaFayette, New York 13084, United States
- Department of Chemistry, State University of New York College of Environmental Science and Forestry, 1 Forestry Dr., Syracuse, New York 13210, United States
- Lewis School of Health Sciences, Clarkson University, 8 Clarkson Avenue, Potsdam, New York 13699, United States
| | - Aaron J. Wolfe
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, United States
- Ichor Life Sciences, Inc., 2651 US Route 11, LaFayette, New York 13084, United States
- Department of Chemistry, State University of New York College of Environmental Science and Forestry, 1 Forestry Dr., Syracuse, New York 13210, United States
- Lewis School of Health Sciences, Clarkson University, 8 Clarkson Avenue, Potsdam, New York 13699, United States
| | - Michael S. Cosgrove
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, 4249 Weiskotten Hall, 766 Irving Avenue, Syracuse, New York 13210, United States
| | - Liviu Movileanu
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, United States
- Department of Biomedical and Chemical Engineering, Syracuse University, 329 Link Hall, Syracuse, New York 13244, United States
- The BioInspired Institute, Syracuse University, Syracuse, New York 13244, United States
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2
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Sun J, Thakur AK, Movileanu L. Current noise of a protein-selective biological nanopore. Proteomics 2022; 22:e2100077. [PMID: 34275190 PMCID: PMC8763983 DOI: 10.1002/pmic.202100077] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 06/27/2021] [Accepted: 07/15/2021] [Indexed: 11/08/2022]
Abstract
1/f current noise is ubiquitous in protein pores, porins, and channels. We have previously shown that a protein-selective biological nanopore with an external protein receptor can function as a 1/f noise generator when a high-affinity protein ligand is reversibly captured by the receptor. Here, we demonstrate that the binding affinity and concentration of the ligand are key determinants for the nature of current noise. For example, 1/f was absent when a protein ligand was reversibly captured at a much lower concentration than its equilibrium dissociation constant against the receptor. Furthermore, we also analyzed the composite current noise that resulted from mixtures of low-affinity and high-affinity ligands against the same receptor. This study highlights the significance of protein recognition events in the current noise fluctuations across biological membranes.
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Affiliation(s)
- Jiaxin Sun
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
| | - Avinash Kumar Thakur
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
| | - Liviu Movileanu
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA,The BioInspired Institute, Syracuse University, Syracuse, New York 13244, USA,Department of Biomedical and Chemical Engineering, Syracuse University, 329 Link Hall, Syracuse, New York 13244, USA,The corresponding author’s contact information: Liviu Movileanu, PhD, Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA. Phone: 315-443-8078;
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3
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CryoEM reconstructions of membrane proteins solved in several amphipathic solvents, nanodisc, amphipol and detergents, yield amphipathic belts of similar sizes corresponding to a common ordered solvent layer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183693. [PMID: 34271006 DOI: 10.1016/j.bbamem.2021.183693] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/28/2021] [Accepted: 06/30/2021] [Indexed: 12/31/2022]
Abstract
To maintain membrane proteins soluble in aqueous solution, amphipathic compounds are used to shield the hydrophobic patch of their membrane insertion, which forms a belt around the protein. This amphipathic belt is seldom looked at due to the difficulty to visualize it. Cryo-EM is now offering this possibility, where belts are visible in 3D reconstructions. We investigated membrane proteins solved in nanodiscs, amphipols or detergents to analyze whether the nature of the amphipathic compound influences the belt size in 3D reconstructions. We identified belt boundaries in map-density distributions and measured distances for every reconstruction. We showed that all the belts create on average similar reconstructions, whether they originate from the same protein, or from protein from different shapes and structures. There is no difference among detergents or types of nanodisc used. These observations illustrate that the belt observed in 3D reconstructions corresponds to the minimum ordered layer around membrane proteins.
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4
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Zampieri V, Hilpert C, Garnier M, Gestin Y, Delolme S, Martin J, Falson P, Launay G, Chaptal V. The Det.Belt Server: A Tool to Visualize and Estimate Amphipathic Solvent Belts around Membrane Proteins. MEMBRANES 2021; 11:459. [PMID: 34206634 PMCID: PMC8307592 DOI: 10.3390/membranes11070459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/11/2021] [Accepted: 06/17/2021] [Indexed: 11/23/2022]
Abstract
Detergents wrap around membrane proteins to form a belt covering the hydrophobic part of the protein serving for membrane insertion and interaction with lipids. The number of detergent monomers forming this belt is usually unknown to investigators, unless dedicated detergent quantification is undertaken, which for many projects is difficult to setup. Yet, having an approximate knowledge of the amount of detergent forming the belt is extremely useful, to better grasp the protein of interest in interaction with its direct environment rather than picturing the membrane protein "naked". We created the Det.Belt server to dress up membrane proteins and represent in 3D the bulk made by detergent molecules wrapping in a belt. Many detergents are included in a database, allowing investigators to screen in silico the effect of different detergents around their membrane protein. The input number of detergents is changeable with fast recomputation of the belt for interactive usage. Metrics representing the belt are readily available together with scripts to render quality 3D images for publication. The Det.Belt server is a tool for biochemists to better grasp their sample.
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Affiliation(s)
- Veronica Zampieri
- EMBL Grenoble, 71 Avenue des Martyrs, CS 90181, CEDEX 9, 38042 Grenoble, France;
| | - Cécile Hilpert
- Molecular Microbiology and Structural Biochemistry Laboratory (CNRS UMR 5086), University of Lyon, IBCP, 7 Passage du Vercors, 69367 Lyon, France; (C.H.); (M.G.); (Y.G.); (S.D.); (J.M.); (P.F.)
| | - Mélanie Garnier
- Molecular Microbiology and Structural Biochemistry Laboratory (CNRS UMR 5086), University of Lyon, IBCP, 7 Passage du Vercors, 69367 Lyon, France; (C.H.); (M.G.); (Y.G.); (S.D.); (J.M.); (P.F.)
| | - Yannick Gestin
- Molecular Microbiology and Structural Biochemistry Laboratory (CNRS UMR 5086), University of Lyon, IBCP, 7 Passage du Vercors, 69367 Lyon, France; (C.H.); (M.G.); (Y.G.); (S.D.); (J.M.); (P.F.)
| | - Sébastien Delolme
- Molecular Microbiology and Structural Biochemistry Laboratory (CNRS UMR 5086), University of Lyon, IBCP, 7 Passage du Vercors, 69367 Lyon, France; (C.H.); (M.G.); (Y.G.); (S.D.); (J.M.); (P.F.)
| | - Juliette Martin
- Molecular Microbiology and Structural Biochemistry Laboratory (CNRS UMR 5086), University of Lyon, IBCP, 7 Passage du Vercors, 69367 Lyon, France; (C.H.); (M.G.); (Y.G.); (S.D.); (J.M.); (P.F.)
| | - Pierre Falson
- Molecular Microbiology and Structural Biochemistry Laboratory (CNRS UMR 5086), University of Lyon, IBCP, 7 Passage du Vercors, 69367 Lyon, France; (C.H.); (M.G.); (Y.G.); (S.D.); (J.M.); (P.F.)
| | - Guillaume Launay
- Molecular Microbiology and Structural Biochemistry Laboratory (CNRS UMR 5086), University of Lyon, IBCP, 7 Passage du Vercors, 69367 Lyon, France; (C.H.); (M.G.); (Y.G.); (S.D.); (J.M.); (P.F.)
| | - Vincent Chaptal
- Molecular Microbiology and Structural Biochemistry Laboratory (CNRS UMR 5086), University of Lyon, IBCP, 7 Passage du Vercors, 69367 Lyon, France; (C.H.); (M.G.); (Y.G.); (S.D.); (J.M.); (P.F.)
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5
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Kinetics of the multitasking high-affinity Win binding site of WDR5 in restricted and unrestricted conditions. Biochem J 2021; 478:2145-2161. [PMID: 34032265 DOI: 10.1042/bcj20210253] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/19/2021] [Accepted: 05/21/2021] [Indexed: 02/05/2023]
Abstract
Recent advances in quantitative proteomics show that WD40 proteins play a pivotal role in numerous cellular networks. Yet, they have been fairly unexplored and their physical associations with other proteins are ambiguous. A quantitative understanding of these interactions has wide-ranging significance. WD40 repeat protein 5 (WDR5) interacts with all members of human SET1/MLL methyltransferases, which regulate methylation of the histone 3 lysine 4 (H3K4). Here, using real-time binding measurements in a high-throughput setting, we identified the kinetic fingerprint of transient associations between WDR5 and 14-residue WDR5 interaction (Win) motif peptides of each SET1 protein (SET1Win). Our results reveal that the high-affinity WDR5-SET1Win interactions feature slow association kinetics. This finding is likely due to the requirement of SET1Win to insert into the narrow WDR5 cavity, also named the Win binding site. Furthermore, our explorations indicate fairly slow dissociation kinetics. This conclusion is in accordance with the primary role of WDR5 in maintaining the functional integrity of a large multisubunit complex, which regulates the histone methylation. Because the Win binding site is considered a key therapeutic target, the immediate outcomes of this study could form the basis for accelerated developments in medical biotechnology.
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Sun J, Thakur AK, Movileanu L. Protein Ligand-Induced Amplification in the 1/ f Noise of a Protein-Selective Nanopore. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:15247-15257. [PMID: 33307706 PMCID: PMC7755739 DOI: 10.1021/acs.langmuir.0c02498] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Previous studies of transmembrane protein channels have employed noise analysis to examine their statistical current fluctuations. In general, these explorations determined a substrate-induced amplification in the Gaussian white noise of these systems at a low-frequency regime. This outcome implies a lack of slowly appearing fluctuations in the number and local mobility of diffusing charges in the presence of channel substrates. Such parameters are among the key factors in generating a low-frequency 1/f noise. Here, we show that a protein-selective biological nanopore exhibits a substrate-induced amplification in the 1/f noise. The modular composition of this biological nanopore includes a hydrophilic transmembrane protein pore fused to a water-soluble binding protein on its extramembranous side. In addition, this protein nanopore shows an open substate populated by a high-frequency current noise because of the flickering of an engineered polypeptide adaptor at the tip of the pore. However, the physical association of the protein ligand with the binding domain reversibly switches the protein nanopore from a high-frequency noise substate into a quiet substate. In the absence of the protein ligand, our nanopore shows a low-frequency white noise. Remarkably, in the presence of the protein ligand, an amplified low-frequency 1/f noise was detected in a ligand concentration-dependent fashion. This finding suggests slowly occurring equilibrium fluctuations in the density and local mobility of charge carriers under these conditions. Furthermore, we report that the excess in 1/f noise is generated by reversible switches between the noisy ligand-released substate and the quiet ligand-captured substate. Finally, quantitative aspects of the low-frequency 1/f noise are in accord with theoretical predictions of the current noise analysis of protein channel-ligand interactions.
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Affiliation(s)
- Jiaxin Sun
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
| | - Avinash Kumar Thakur
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
- Structural Biology, Biochemistry, and Biophysics Program, Syracuse University, 111 College Place, Syracuse, New York 13244-4100, USA
| | - Liviu Movileanu
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
- Structural Biology, Biochemistry, and Biophysics Program, Syracuse University, 111 College Place, Syracuse, New York 13244-4100, USA
- Department of Biomedical and Chemical Engineering, Syracuse University, 329 Link Hall, Syracuse, New York 13244, USA
- The corresponding author’s contact information: Liviu Movileanu, PhD, Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA. Phone: 315-443-8078; Fax: 315-443-9103;
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7
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Effects of Detergent on α-Synuclein Structure. A Native MS-Ion Mobility Study. Int J Mol Sci 2020; 21:ijms21217884. [PMID: 33114222 PMCID: PMC7660655 DOI: 10.3390/ijms21217884] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 10/16/2020] [Accepted: 10/21/2020] [Indexed: 02/06/2023] Open
Abstract
The intrinsically disordered protein α-synuclein plays a major role in Parkinson’s disease. The protein can oligomerize resulting in the formation of various aggregated species in neuronal cells, leading to neurodegeneration. The interaction of α-synuclein with biological cell membranes plays an important role for specific functions of α-synuclein monomers, e.g., in neurotransmitter release. Using different types of detergents to mimic lipid molecules present in biological membranes, including the presence of Ca2+ ions as an important structural factor, we aimed to gain an understanding of how α-synuclein interacts with membrane models and how this affects the protein conformation and potential oligomerization. We investigated detergent binding stoichiometry, affinity and conformational changes of α-synuclein taking detergent concentration, different detergent structures and charges into account. With native nano-electrospray ionization ion mobility-mass spectrometry, we were able to detect unique conformational patterns resulting from binding of specific detergents to α-synuclein. Our data demonstrate that α-synuclein monomers can interact with detergent molecules irrespective of their charge, that protein-micelle interactions occur and that micelle properties are an important factor.
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8
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Winogradoff D, John S, Aksimentiev A. Protein unfolding by SDS: the microscopic mechanisms and the properties of the SDS-protein assembly. NANOSCALE 2020; 12:5422-5434. [PMID: 32080694 PMCID: PMC7291819 DOI: 10.1039/c9nr09135a] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The effects of detergent sodium dodecyl sulfate (SDS) on protein structure and dynamics are fundamental to the most common laboratory technique used to separate proteins and determine their molecular weights: polyacrylamide gel electrophoresis. However, the mechanism by which SDS induces protein unfolding and the microstructure of protein-SDS complexes remain largely unknown. Here, we report a detailed account of SDS-induced unfolding of two proteins-I27 domain of titin and β-amylase-obtained through all-atom molecular dynamics simulations. Both proteins were found to spontaneously unfold in the presence of SDS at boiling water temperature on the time scale of several microseconds. The protein unfolding was found to occur via two distinct mechanisms in which specific interactions of individual SDS molecules disrupt the protein's secondary structure. In the final state of the unfolding process, the proteins are found to wrap around SDS micelles in a fluid necklace-and-beads configuration, where the number and location of bound micelles changes dynamically. The global conformation of the protein was found to correlate with the number of SDS micelles bound to it, whereas the number of SDS molecules directly bound to the protein was found to define the relaxation time scale of the unfolded protein. Our microscopic characterization of SDS-protein interactions sets the stage for future refinement of SDS-enabled protein characterization methods, including protein fingerprinting and sequencing using a solid-state nanopore.
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Affiliation(s)
- David Winogradoff
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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9
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Thakur AK, Movileanu L. Single-Molecule Protein Detection in a Biofluid Using a Quantitative Nanopore Sensor. ACS Sens 2019; 4:2320-2326. [PMID: 31397162 DOI: 10.1021/acssensors.9b00848] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Protein detection in complex biological fluids has wide-ranging significance across proteomics and molecular medicine. Existing detectors cannot readily distinguish between specific and nonspecific interactions in a heterogeneous solution. Here, we show that this daunting shortcoming can be overcome by using a protein bait-containing biological nanopore in mammalian serum. The capture and release events of a protein analyte by the tethered protein bait occur outside the nanopore and are accompanied by uniform current openings. Conversely, nonspecific pore penetrations by nontarget components of serum, which take place inside the nanopore, are featured by irregular current blockades. As a result of this unique peculiarity of the readout between specific protein captures and nonspecific pore penetration events, our selective sensor can quantitatively sample proteins at single-molecule precision in a manner distinctive from those employed by prevailing methods. Because our sensor can be integrated into nanofluidic devices and coupled with high-throughput technologies, our approach will have a transformative impact in protein identification and quantification in clinical isolates for disease prognostics and diagnostics.
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Affiliation(s)
- Avinash Kumar Thakur
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, United States
- Structural Biology, Biochemistry, and Biophysics Program, Syracuse University, 111 College Place, Syracuse, New York 13244-4100, United States
| | - Liviu Movileanu
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, United States
- Structural Biology, Biochemistry, and Biophysics Program, Syracuse University, 111 College Place, Syracuse, New York 13244-4100, United States
- Department of Biomedical and Chemical Engineering, Syracuse University, 329 Link Hall, Syracuse, New York 13244, United States
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10
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Wolfe AJ, Parella KJ, Movileanu L. High-Throughput Screening of Protein-Detergent Complexes Using Fluorescence Polarization Spectroscopy. ACTA ACUST UNITED AC 2019; 97:e96. [PMID: 31517448 DOI: 10.1002/cpps.96] [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: 11/07/2022]
Abstract
This article provides detailed protocols for a high-throughput fluorescence polarization (FP) spectroscopy approach to disentangle the interactions of membrane proteins with solubilizing detergents. Existing techniques for examining the membrane protein-detergent complex (PDC) interactions are low throughput and require high amounts of proteins. Here, we describe a 96-well analytical approach, which facilitates a scalable analysis of the PDC interactions at low-nanomolar concentrations of membrane proteins in native solutions. At detergent concentrations much greater than the equilibrium dissociation constant of the PDC, Kd , the FP anisotropy reaches a saturated value, so it is independent of the detergent concentration. On the contrary, at detergent concentrations comparable with or lower than the Kd , the FP anisotropy readout undergoes a time-dependent decrease, exhibiting a sensitive and specific detergent-dissociation signature. Our approach can also be used for determining the kinetic rate constants of association and dissociation. With further development, these protocols might be used in various arenas of membrane protein research that pertain to extraction, solubilization, and stabilization. © 2019 by John Wiley & Sons, Inc.
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Affiliation(s)
- Aaron J Wolfe
- Ichor Therapeutics, Inc., LaFayette, New York.,Department of Chemistry, State University of New York College of Environmental Science and Forestry, Syracuse, New York
| | - Kyle J Parella
- Ichor Therapeutics, Inc., LaFayette, New York.,Department of Chemistry, State University of New York College of Environmental Science and Forestry, Syracuse, New York
| | - Liviu Movileanu
- Department of Physics, Syracuse University, Syracuse, New York.,Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York
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Burns JR, Howorka S. Structural and Functional Stability of DNA Nanopores in Biological Media. NANOMATERIALS 2019; 9:nano9040490. [PMID: 30934927 PMCID: PMC6523550 DOI: 10.3390/nano9040490] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 03/22/2019] [Accepted: 03/23/2019] [Indexed: 01/20/2023]
Abstract
DNA nanopores offer a unique nano-scale foothold at the membrane interface that can help advance the life sciences as biophysical research tools or gate-keepers for drug delivery. Biological applications require sufficient physiological stability and membrane activity for viable biological action. In this report, we determine essential parameters for efficient nanopore folding and membrane binding in biocompatible cell media. The parameters are identified for an archetypal DNA nanopore composed of six interwoven strands carrying cholesterol lipid anchors. Using gel electrophoresis and fluorescence spectroscopy, the nanostructures are found to assemble efficiently in cell media, such as LB and DMEM, and remain structurally stable at physiological temperatures. Furthermore, the pores’ oligomerization state is monitored using fluorescence spectroscopy and confocal microscopy. The pores remain predominately water-soluble over 24 h in all buffer systems, and were able to bind to lipid vesicles after 24 h to confirm membrane activity. However, the addition of fetal bovine serum to DMEM causes a significant reduction in nanopore activity. Serum proteins complex rapidly to the pore, most likely via ionic interactions, to reduce the effective nanopore concentration in solution. Our findings outline crucial conditions for maintaining lipidated DNA nanodevices, structurally and functionally intact in cell media, and pave the way for biological studies in the future.
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Affiliation(s)
- Jonathan R Burns
- Department of Chemistry, Institute of Structural Molecular Biology, University College London, London WC1H 0AJ, UK.
| | - Stefan Howorka
- Department of Chemistry, Institute of Structural Molecular Biology, University College London, London WC1H 0AJ, UK.
- Institute of Biophysics, Johannes Kepler University, A-4020 Linz, Austria.
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12
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Xue D, Wang J, Song X, Wang W, Hu T, Ye L, Liu Y, Zhou Q, Zhou F, Jiang ZX, Liu ZJ, Tao H. A Chemical Strategy for Amphiphile Replacement in Membrane Protein Research. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:4319-4327. [PMID: 30781953 DOI: 10.1021/acs.langmuir.8b04072] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Membrane mimics are indispensable tools in the structural and functional understanding of membrane proteins (MPs). Given stringent requirements of integral MP manipulations, amphiphile replacement is often required in sample preparation for various biophysical purposes. Current protocols generally rely on physical methodologies and rarely reach complete replacement. In comparison, we report herein a chemical alternative that facilitates the exhaustive exchange of membrane-mimicking systems for MP reconstitution. This method, named sacrifice-replacement strategy, was enabled by a class of chemically cleavable detergents (CCDs), derived from the disulfide incorporation in the traditional detergent n-dodecyl-β-d-maltopyranoside. The representative CCD behaved well in both solubilizing the diverse α-helical human G protein-coupled receptors and refolding of the β-barrel bacterial outer membrane protein X, and more importantly, it could also be readily degraded under mild conditions. By this means, the A2A adenosine receptor was successfully reconstituted into a series of commercial detergents for stabilization screening and nanodiscs for electron microscopy analysis. Featured by the simplicity and compatibility, this CCD-mediated strategy would later find more applications when being integrated in other biophysics studies.
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Affiliation(s)
- Dongxiang Xue
- iHuman Institute , ShanghaiTech University , Ren Building, 393 Middle Huaxia Road , Shanghai 201210 , China
- Shanghai Institute of Materia Medica , Chinese Academy of Sciences , 555 Zuchongzhi Road , Shanghai 201203 , China
- University of Chinese Academy of Sciences , No. 19A, Yuquan Road , Beijing 100049 , China
- School of Life Science and Technology , ShanghaiTech University , Shanghai 201210 , China
| | - Jingjing Wang
- iHuman Institute , ShanghaiTech University , Ren Building, 393 Middle Huaxia Road , Shanghai 201210 , China
- University of Chinese Academy of Sciences , No. 19A, Yuquan Road , Beijing 100049 , China
- School of Life Science and Technology , ShanghaiTech University , Shanghai 201210 , China
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences , Chinese Academy of Sciences , Shanghai 200031 , China
| | - Xiyong Song
- University of Chinese Academy of Sciences , No. 19A, Yuquan Road , Beijing 100049 , China
- National Laboratory of Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , Beijing 100101 , China
| | - Wei Wang
- Hubei Province Engineering and Technology Research Center for Fluorinated Pharmaceuticals, School of Pharmaceutical Sciences , Wuhan University , Wuhan 430071 , China
| | - Tao Hu
- iHuman Institute , ShanghaiTech University , Ren Building, 393 Middle Huaxia Road , Shanghai 201210 , China
- Shanghai Institute of Materia Medica , Chinese Academy of Sciences , 555 Zuchongzhi Road , Shanghai 201203 , China
- University of Chinese Academy of Sciences , No. 19A, Yuquan Road , Beijing 100049 , China
- School of Life Science and Technology , ShanghaiTech University , Shanghai 201210 , China
| | - Lintao Ye
- iHuman Institute , ShanghaiTech University , Ren Building, 393 Middle Huaxia Road , Shanghai 201210 , China
| | - Yang Liu
- iHuman Institute , ShanghaiTech University , Ren Building, 393 Middle Huaxia Road , Shanghai 201210 , China
| | - Qingtong Zhou
- iHuman Institute , ShanghaiTech University , Ren Building, 393 Middle Huaxia Road , Shanghai 201210 , China
| | - Fang Zhou
- iHuman Institute , ShanghaiTech University , Ren Building, 393 Middle Huaxia Road , Shanghai 201210 , China
- Shanghai Institute of Materia Medica , Chinese Academy of Sciences , 555 Zuchongzhi Road , Shanghai 201203 , China
- University of Chinese Academy of Sciences , No. 19A, Yuquan Road , Beijing 100049 , China
- School of Life Science and Technology , ShanghaiTech University , Shanghai 201210 , China
| | - Zhong-Xing Jiang
- Hubei Province Engineering and Technology Research Center for Fluorinated Pharmaceuticals, School of Pharmaceutical Sciences , Wuhan University , Wuhan 430071 , China
| | - Zhi-Jie Liu
- iHuman Institute , ShanghaiTech University , Ren Building, 393 Middle Huaxia Road , Shanghai 201210 , China
- School of Life Science and Technology , ShanghaiTech University , Shanghai 201210 , China
| | - Houchao Tao
- iHuman Institute , ShanghaiTech University , Ren Building, 393 Middle Huaxia Road , Shanghai 201210 , China
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Wilson J, Sarthak K, Si W, Gao L, Aksimentiev A. Rapid and Accurate Determination of Nanopore Ionic Current Using a Steric Exclusion Model. ACS Sens 2019; 4:634-644. [PMID: 30821441 DOI: 10.1021/acssensors.8b01375] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Nanopore sensing has emerged as a versatile approach to detection and identification of biomolecules. Presently, researchers rely on experience and intuition for choosing or modifying the nanopores to detect a target analyte. The field would greatly benefit from a computational method that could relate the atomic-scale geometry of the nanopores and analytes to the blockade nanopore currents they produce. Existing computational methods are either computationally too expensive to be used routinely in experimental laboratories or not sensitive enough to account for the atomic structure of the pore and the analytes. Here, we demonstrate a robust and inexpensive computational approach-the steric exclusion model (SEM) of nanopore conductance-that is orders of magnitude more efficient than all-atom MD and yet is sensitive enough to account for the atomic structure of the nanopore and the analyte. The method combines the computational efficiency of a finite element solver with the atomic precision of a nanopore conductance map to yield unprecedented speed and accuracy of ionic current prediction. We validate our SEM approach through comparison with the current blockades computed using the all-atom molecular dynamics method for a range of proteins confined to a solid-state nanopore, biological channels embedded in a lipid bilayer membranes, and blockade currents produced by DNA homopolymers in MspA. We illustrate potential applications of SEM by computing blockade currents produced by nucleosome proteins in a solid-state nanopore, individual amino acids in MspA, and by testing the effect of point mutations on amino acid distinguishability. We expect our SEM approach to become an integral part of future development of the nanopore sensing field.
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Affiliation(s)
| | | | - Wei Si
- Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments and School of Mechanical Engineering, Southeast University, Nanjing, 210096, China
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Brady NG, Qian S, Bruce BD. Analysis of styrene maleic acid alternating copolymer supramolecular assemblies in solution by small angle X-ray scattering. Eur Polym J 2019. [DOI: 10.1016/j.eurpolymj.2018.11.034] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Successful amphiphiles as the key to crystallization of membrane proteins: Bridging theory and practice. Biochim Biophys Acta Gen Subj 2018; 1863:437-455. [PMID: 30419284 DOI: 10.1016/j.bbagen.2018.11.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 10/31/2018] [Accepted: 11/07/2018] [Indexed: 12/17/2022]
Abstract
BACKGROUND Membrane proteins constitute a major group of proteins and are of great significance as pharmaceutical targets, but underrepresented in the Protein Data Bank. Particular reasons are their low expression yields and the constant need for cautious and diligent handling in a sufficiently stable hydrophobic environment substituting for the native membrane. When it comes to protein crystallization, such an environment is often established by detergents. SCOPE OF REVIEW In this review, 475 unique membrane protein X-ray structures from the online data bank "Membrane proteins of known 3D structure" are presented with a focus on the detergents essential for protein crystallization. By systematic analysis of the most successful compounds, including current trends in amphiphile development, we provide general insights for selection and design of detergents for membrane protein crystallization. MAJOR CONCLUSIONS The most successful detergents share common features, giving rise to favorable protein interactions. The hydrophile-lipophile balance concept of well-balanced hydrophilic and hydrophobic detergent portions is still the key to successful protein crystallization. Although a single detergent compound is sufficient in most cases, sometimes a suitable mixture of detergents has to be found to alter the resulting protein-detergent complex. Protein crystals with a high diffraction limit involve a tight crystal packing generally favored by detergents with shorter alkyl chains. GENERAL SIGNIFICANCE The formation of well-diffracting membrane protein crystals strongly depends on suitable surfactants, usually screened in numerous crystallization trials. The here-presented findings provide basic criteria for the assessment of surfactants within the vast space of potential crystallization conditions for membrane proteins.
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Wolfe AJ, Gugel JF, Chen M, Movileanu L. Kinetics of Membrane Protein-Detergent Interactions Depend on Protein Electrostatics. J Phys Chem B 2018; 122:9471-9481. [PMID: 30251852 DOI: 10.1021/acs.jpcb.8b07889] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Interactions of a membrane protein with a detergent micelle represent a fundamental process with practical implications in structural and chemical biology. Quantitative assessment of the kinetics of protein-detergent complex (PDC) interactions has always been challenged by complicated behavior of both membrane proteins and solubilizing detergents in aqueous phase. Here, we show the kinetic reads of the desorption of maltoside-containing detergents from β-barrel membrane proteins. Using steady-state fluorescence polarization (FP) anisotropy measurements, we recorded real-time, specific signatures of the PDC interactions. The results of these measurements were used to infer the model-dependent rate constants of association and dissociation of the proteomicelles. Remarkably, the kinetics of the PDC interactions depend on the overall protein charge despite the nonionic nature of the detergent monomers. In the future, this approach might be employed for high-throughput screening of kinetic fingerprints of different membrane proteins stabilized in micelles that contain mixtures of various detergents.
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Affiliation(s)
- Aaron J Wolfe
- Department of Physics , Syracuse University , 201 Physics Building , Syracuse , New York 13244-1130 , United States.,Structural Biology, Biochemistry, and Biophysics Program , Syracuse University , 111 College Place , Syracuse , New York 13244-4100 , United States
| | - Jack F Gugel
- Department of Physics , Syracuse University , 201 Physics Building , Syracuse , New York 13244-1130 , United States
| | - Min Chen
- Department of Chemistry , University of Massachusetts , 820 LGRT, 710 North Pleasant Street , Amherst , Massachusetts 01003-9336 , United States
| | - Liviu Movileanu
- Department of Physics , Syracuse University , 201 Physics Building , Syracuse , New York 13244-1130 , United States.,Structural Biology, Biochemistry, and Biophysics Program , Syracuse University , 111 College Place , Syracuse , New York 13244-4100 , United States.,Department of Biomedical and Chemical Engineering , Syracuse University , 223 Link Hall , Syracuse , New York 13244 , United States
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Wolfe AJ, Gugel JF, Chen M, Movileanu L. Detergent Desorption of Membrane Proteins Exhibits Two Kinetic Phases. J Phys Chem Lett 2018; 9:1913-1919. [PMID: 29595981 PMCID: PMC5908730 DOI: 10.1021/acs.jpclett.8b00549] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Gradual dissociation of detergent molecules from water-insoluble membrane proteins culminates in protein aggregation. However, the time-dependent trajectory of this process remains ambiguous because the signal-to-noise ratio of most spectroscopic and calorimetric techniques is drastically declined by the presence of protein aggregates in solution. We show that by using steady-state fluorescence polarization (FP) spectroscopy the dissociation of the protein-detergent complex (PDC) can be inspected in real time at detergent concentrations below the critical micelle concentration. This article provides experimental evidence of the coexistence of two distinct phases of the dissociations of detergent monomers from membrane proteins. We first noted a slow detergent predesolvation process, which was accompanied by a relatively modest change in the FP anisotropy, suggesting a small number of dissociated detergent monomers from the proteomicelles. This predesolvation phase was followed by a fast detergent desolvation process, which was highlighted by a major alteration in the FP anisotropy. The durations and rates of these phases were dependent on both the detergent concentration and the interfacial PDC interactions. Further development of this approach might lead to the creation of a new semiquantitative method for the assessment of the kinetics of association and dissociation of proteomicelles.
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Affiliation(s)
- Aaron J. Wolfe
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
- Structural Biology, Biochemistry, and Biophysics Program, Syracuse University, 111 College Place, Syracuse, New York 13244-4100, USA
| | - Jack F. Gugel
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
| | - Min Chen
- Department of Chemistry, University of Massachusetts Amherst, 820 LGRT, 710 North Pleasant Street, Amherst, Massachusetts 01003-9336, USA
| | - Liviu Movileanu
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
- Structural Biology, Biochemistry, and Biophysics Program, Syracuse University, 111 College Place, Syracuse, New York 13244-4100, USA
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse University, 223 Link Hall, Syracuse, New York 13244, USA
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