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Li X, Fu YH, Wei N, Yu RJ, Bhatti H, Zhang L, Yan F, Xia F, Ewing AG, Long YT, Ying YL. Emerging Data Processing Methods for Single-Entity Electrochemistry. Angew Chem Int Ed Engl 2024; 63:e202316551. [PMID: 38411372 DOI: 10.1002/anie.202316551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 02/12/2024] [Accepted: 02/26/2024] [Indexed: 02/28/2024]
Abstract
Single-entity electrochemistry is a powerful tool that enables the study of electrochemical processes at interfaces and provides insights into the intrinsic chemical and structural heterogeneities of individual entities. Signal processing is a critical aspect of single-entity electrochemical measurements and can be used for data recognition, classification, and interpretation. In this review, we summarize the recent five-year advances in signal processing techniques for single-entity electrochemistry and highlight their importance in obtaining high-quality data and extracting effective features from electrochemical signals, which are generally applicable in single-entity electrochemistry. Moreover, we shed light on electrochemical noise analysis to obtain single-molecule frequency fingerprint spectra that can provide rich information about the ion networks at the interface. By incorporating advanced data analysis tools and artificial intelligence algorithms, single-entity electrochemical measurements would revolutionize the field of single-entity analysis, leading to new fundamental discoveries.
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Affiliation(s)
- Xinyi Li
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 210023, Nanjing, P. R. China
| | - Ying-Huan Fu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 210023, Nanjing, P. R. China
| | - Nannan Wei
- School of Electronic Science and Engineering, Nanjing University, 210023, Nanjing, P. R. China
| | - Ru-Jia Yu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 210023, Nanjing, P. R. China
- Chemistry and Biomedicine Innovation Center, Nanjing University, 210023, Nanjing, P. R. China
| | - Huma Bhatti
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 210023, Nanjing, P. R. China
| | - Limin Zhang
- School of Electronic Science and Engineering, Nanjing University, 210023, Nanjing, P. R. China
| | - Feng Yan
- School of Electronic Science and Engineering, Nanjing University, 210023, Nanjing, P. R. China
| | - Fan Xia
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, 430034, Wuhan, P. R. China
| | - Andrew G Ewing
- Department of Chemistry and Molecular Biology, University of Gothenburg, 41296, Gothenburg, Sweden
| | - Yi-Tao Long
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 210023, Nanjing, P. R. China
| | - Yi-Lun Ying
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 210023, Nanjing, P. R. China
- Chemistry and Biomedicine Innovation Center, Nanjing University, 210023, Nanjing, P. R. China
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2
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Shi Z, Zhang Q, Wang X. Does the disclosure of medical insurance information affect patients' willingness to adopt the diagnosis related groups system. Front Public Health 2023; 11:1136178. [PMID: 37670832 PMCID: PMC10475549 DOI: 10.3389/fpubh.2023.1136178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 05/31/2023] [Indexed: 09/07/2023] Open
Abstract
Introduction Medical insurance information disclosure is not only a direct way for the public to understand and master social insurance information and resource use benefits, but also an important way for the public to participate in medical service governance and supervision. Some studies have shown that information disclosure can significantly reduce the risk perception of user groups, strengthen their trust and reduce the negative impact of information asymmetry. Methods Based on risk perception and trust perception theories, this paper focuses on the mechanisms influencing patients' attitudes in the process of implementing a Diagnosis Related Groups payment system. Using medical insurance information disclosure from a governance perspective as the research object, the impact of medical insurance information disclosure on patients' willingness to adopt the Diagnosis Related Groups payment system was analyzed by means of a questionnaire survey, Data analysis and hypothesis testing via SPSS while the mechanism of the impact of medical insurance information disclosure on patients' attitudes was explored in depth. Results It was found that medical insurance information disclosure had a significant positive effect on patients' trust perceptions and a significant negative effect on patients' risk perceptions. The more comprehensive information patients received, the stronger their trust and the lower their perceived risk. Discussion This paper conducts an empirical study from patients' perspective, broadens the scope of research on medical insurance Diagnosis related groups, enriches the application of risk perception and trust perception theories in the medical field, and provides management suggestions for medical institutions in the management of medical insurance information disclosure.
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Affiliation(s)
- Zhenni Shi
- School of Political Science and Public Management, Wuhan University, Wuhan, China
| | - Qilin Zhang
- School of Political Science and Public Management, Wuhan University, Wuhan, China
| | - Xiaofeng Wang
- College of Management, Shenzhen University, Shenzhen, China
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3
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Mayse LA, Movileanu L. Gating of β-Barrel Protein Pores, Porins, and Channels: An Old Problem with New Facets. Int J Mol Sci 2023; 24:12095. [PMID: 37569469 PMCID: PMC10418385 DOI: 10.3390/ijms241512095] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 07/23/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
β barrels are ubiquitous proteins in the outer membranes of mitochondria, chloroplasts, and Gram-negative bacteria. These transmembrane proteins (TMPs) execute a wide variety of tasks. For example, they can serve as transporters, receptors, membrane-bound enzymes, as well as adhesion, structural, and signaling elements. In addition, multimeric β barrels are common structural scaffolds among many pore-forming toxins. Significant progress has been made in understanding the functional, structural, biochemical, and biophysical features of these robust and versatile proteins. One frequently encountered fundamental trait of all β barrels is their voltage-dependent gating. This process consists of reversible or permanent conformational transitions between a large-conductance, highly permeable open state and a low-conductance, solute-restrictive closed state. Several intrinsic molecular mechanisms and environmental factors modulate this universal property of β barrels. This review article outlines the typical signatures of voltage-dependent gating. Moreover, we discuss recent developments leading to a better qualitative understanding of the closure dynamics of these TMPs.
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Affiliation(s)
- Lauren A. Mayse
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY 13244, USA;
- Department of Biomedical and Chemical Engineering, Syracuse University, 223 Link Hall, Syracuse, NY 13244, USA
| | - Liviu Movileanu
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY 13244, USA;
- Department of Biomedical and Chemical Engineering, Syracuse University, 223 Link Hall, Syracuse, NY 13244, USA
- The BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA
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4
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Jeong KB, Ryu M, Kim JS, Kim M, Yoo J, Chung M, Oh S, Jo G, Lee SG, Kim HM, Lee MK, Chi SW. Single-molecule fingerprinting of protein-drug interaction using a funneled biological nanopore. Nat Commun 2023; 14:1461. [PMID: 37015934 PMCID: PMC10073129 DOI: 10.1038/s41467-023-37098-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 03/01/2023] [Indexed: 04/06/2023] Open
Abstract
In drug discovery, efficient screening of protein-drug interactions (PDIs) is hampered by the limitations of current biophysical approaches. Here, we develop a biological nanopore sensor for single-molecule detection of proteins and PDIs using the pore-forming toxin YaxAB. Using this YaxAB nanopore, we demonstrate label-free, single-molecule detection of interactions between the anticancer Bcl-xL protein and small-molecule drugs as well as the Bak-BH3 peptide. The long funnel-shaped structure and nanofluidic characteristics of the YaxAB nanopore enable the electro-osmotic trapping of diverse folded proteins and high-resolution monitoring of PDIs. Distinctive nanopore event distributions observed in the two-dimensional (ΔI/Io-versus-IN) plot illustrate the ability of the YaxAB nanopore to discriminate individual small-molecule drugs bound to Bcl-xL from non-binders. Taken together, our results present the YaxAB nanopore as a robust platform for label-free, ultrasensitive, single-molecule detection of PDIs, opening up a possibility for low-cost, highly efficient drug discovery against diverse drug targets.
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Affiliation(s)
- Ki-Baek Jeong
- Disease Target Structure Research Center, Division of Biomedical Research, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
- Critical Diseases Diagnostics Convergence Research Center, KRIBB, Daejeon, 34141, Republic of Korea
| | - Minju Ryu
- Disease Target Structure Research Center, Division of Biomedical Research, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
- Department of Proteome Structural Biology, KRIBB School of Bioscience, University of Science and Technology, Daejeon, 34113, Republic of Korea
| | - Jin-Sik Kim
- Disease Target Structure Research Center, Division of Biomedical Research, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
- Critical Diseases Diagnostics Convergence Research Center, KRIBB, Daejeon, 34141, Republic of Korea
| | - Minsoo Kim
- Department of Physics, Sungkyunkwan University, Suwon, Gyeonggi, 16419, Republic of Korea
| | - Jejoong Yoo
- Department of Physics, Sungkyunkwan University, Suwon, Gyeonggi, 16419, Republic of Korea
| | - Minji Chung
- Disease Target Structure Research Center, Division of Biomedical Research, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
| | - Sohee Oh
- Disease Target Structure Research Center, Division of Biomedical Research, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
| | - Gyunghee Jo
- Center for Biomolecular and Cellular Structure, Institute for Basic Science (IBS), Daejeon, 34126, Republic of Korea
| | - Seong-Gyu Lee
- Center for Biomolecular and Cellular Structure, Institute for Basic Science (IBS), Daejeon, 34126, Republic of Korea
| | - Ho Min Kim
- Center for Biomolecular and Cellular Structure, Institute for Basic Science (IBS), Daejeon, 34126, Republic of Korea
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Mi-Kyung Lee
- Disease Target Structure Research Center, Division of Biomedical Research, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea.
- Critical Diseases Diagnostics Convergence Research Center, KRIBB, Daejeon, 34141, Republic of Korea.
- Department of Proteome Structural Biology, KRIBB School of Bioscience, University of Science and Technology, Daejeon, 34113, Republic of Korea.
| | - Seung-Wook Chi
- Disease Target Structure Research Center, Division of Biomedical Research, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea.
- Department of Proteome Structural Biology, KRIBB School of Bioscience, University of Science and Technology, Daejeon, 34113, Republic of Korea.
- School of Pharmacy, Sungkyunkwan University, Suwon, Gyeonggi, 16419, Republic of Korea.
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5
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Ahmad M, Ha JH, Mayse LA, Presti MF, Wolfe AJ, Moody KJ, Loh SN, Movileanu L. A generalizable nanopore sensor for highly specific protein detection at single-molecule precision. Nat Commun 2023; 14:1374. [PMID: 36941245 PMCID: PMC10027671 DOI: 10.1038/s41467-023-36944-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Accepted: 02/23/2023] [Indexed: 03/23/2023] Open
Abstract
Protein detection has wide-ranging implications in molecular diagnostics. Substantial progress has been made in protein analytics using nanopores and the resistive-pulse technique. Yet, a long-standing challenge is implementing specific interfaces for detecting proteins without the steric hindrance of the pore interior. Here, we formulate a class of sensing elements made of a programmable antibody-mimetic binder fused to a monomeric protein nanopore. This way, such a modular design significantly expands the utility of nanopore sensors to numerous proteins while preserving their architecture, specificity, and sensitivity. We prove the power of this approach by developing and validating nanopore sensors for protein analytes that drastically vary in size, charge, and structural complexity. These analytes produce unique electrical signatures that depend on their identity and quantity and the binder-analyte assembly at the nanopore tip. The outcomes of this work could impact biomedical diagnostics by providing a fundamental basis for biomarker detection in biofluids.
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Affiliation(s)
- Mohammad Ahmad
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY, 13244-1130, USA
| | - Jeung-Hoi Ha
- Department of Biochemistry and Molecular Biology, State University of New York-Upstate Medical University, 4249 Weiskotten Hall, 766 Irving Avenue, Syracuse, NY, 13210, USA
| | - Lauren A Mayse
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY, 13244-1130, USA
- Department of Biomedical and Chemical Engineering, Syracuse University, 329 Link Hall, Syracuse, NY, 13244, USA
| | - Maria F Presti
- Department of Biochemistry and Molecular Biology, State University of New York-Upstate Medical University, 4249 Weiskotten Hall, 766 Irving Avenue, Syracuse, NY, 13210, USA
| | - Aaron J Wolfe
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY, 13244-1130, USA
- Ichor Life Sciences, Inc., 2561 US Route 11, LaFayette, NY, 13084, USA
- Lewis School of Health Sciences, Clarkson University, 8 Clarkson Avenue, Potsdam, NY, 13699, USA
- Department of Chemistry, College of Environmental Science and Forestry, State University of New York, 1 Forestry Drive, Syracuse, NY, 13210, USA
| | - Kelsey J Moody
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY, 13244-1130, USA
- Ichor Life Sciences, Inc., 2561 US Route 11, LaFayette, NY, 13084, USA
- Lewis School of Health Sciences, Clarkson University, 8 Clarkson Avenue, Potsdam, NY, 13699, USA
- Department of Chemistry, College of Environmental Science and Forestry, State University of New York, 1 Forestry Drive, Syracuse, NY, 13210, USA
| | - Stewart N Loh
- Department of Biochemistry and Molecular Biology, State University of New York-Upstate Medical University, 4249 Weiskotten Hall, 766 Irving Avenue, Syracuse, NY, 13210, USA
| | - Liviu Movileanu
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY, 13244-1130, USA.
- Department of Biomedical and Chemical Engineering, Syracuse University, 329 Link Hall, Syracuse, NY, 13244, USA.
- The BioInspired Institute, Syracuse University, Syracuse, NY, 13244, USA.
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6
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Hwang HJ, Kim JS, Lee J, Min JS, Jeong KB, Kim E, Lee MK, Chi SW. Single-Molecule Sensing of an Anticancer Therapeutic Protein-Protein Interaction Using the Chemically Modified OmpG Nanopore. Anal Chem 2022; 94:7449-7454. [PMID: 35583342 DOI: 10.1021/acs.analchem.1c04840] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nanopore sensors are a highly attractive platform for single-molecule sensing for sequencing, disease diagnostics, and drug screening. Outer membrane protein G (OmpG) nanopores have advantages for single-molecule sensing owing to their rigid monomeric structure, which comprises seven flexible loops, providing distinct gating patterns upon analyte binding. Blocking of the protein-protein interaction between B-cell lymphoma-extra-large (Bcl-xL) and the BH3 domain of Bcl-2 homologous antagonist/killer (Bak-BH3) has been reported as a promising strategy for anticancer therapy. Here, we characterized the interaction between Bcl-xL and Bak-BH3 as well as its inhibition by a small-molecule inhibitor using click chemistry-based Bak-BH3 peptide-conjugated OmpG nanopores. The binding of Bcl-xL to Bak-BH3 generated characteristic gating signals involving significant changes in the amplitudes of noise and gating parameters such as gating frequency, open probability, and durations of open and closed states. Notably, specific inhibition of Bcl-xL by the small-molecule antagonist, ABT-737, led to the recovery of the noise and gating parameters. Collectively, these results revealed that the chemically modified OmpG nanopore can serve as a valuable sensor platform for ultrasensitive, rapid, and single-molecule-based drug screening against protein-protein interactions, which are therapeutic targets for various diseases.
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Affiliation(s)
- Hye-Jin Hwang
- Disease Target Structure Research Center, Division of Biomedical Research, KRIBB, Daejeon 34141, Republic of Korea.,Department of Proteome Structural Biology, KRIBB School of Bioscience, University of Science and Technology, Daejeon 34113, Republic of Korea
| | - Jin-Sik Kim
- Disease Target Structure Research Center, Division of Biomedical Research, KRIBB, Daejeon 34141, Republic of Korea
| | - Jeonghyun Lee
- Department of Molecular Science and Technology, Ajou University, Suwon 16499, Republic of Korea
| | - Jun Sik Min
- Department of Molecular Science and Technology, Ajou University, Suwon 16499, Republic of Korea
| | - Ki-Baek Jeong
- Disease Target Structure Research Center, Division of Biomedical Research, KRIBB, Daejeon 34141, Republic of Korea
| | - Eunha Kim
- Department of Molecular Science and Technology, Ajou University, Suwon 16499, Republic of Korea
| | - Mi-Kyung Lee
- Disease Target Structure Research Center, Division of Biomedical Research, KRIBB, Daejeon 34141, Republic of Korea.,Department of Proteome Structural Biology, KRIBB School of Bioscience, University of Science and Technology, Daejeon 34113, Republic of Korea
| | - Seung-Wook Chi
- Disease Target Structure Research Center, Division of Biomedical Research, KRIBB, Daejeon 34141, Republic of Korea.,Department of Proteome Structural Biology, KRIBB School of Bioscience, University of Science and Technology, Daejeon 34113, Republic of Korea
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7
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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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8
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Mayse LA, Imran A, Larimi MG, Cosgrove MS, Wolfe AJ, Movileanu L. Disentangling the recognition complexity of a protein hub using a nanopore. Nat Commun 2022; 13:978. [PMID: 35190547 PMCID: PMC8861093 DOI: 10.1038/s41467-022-28465-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 01/25/2022] [Indexed: 11/12/2022] Open
Abstract
WD40 repeat proteins are frequently involved in processing cell signaling and scaffolding large multi-subunit machineries. Despite their significance in physiological and disease-like conditions, their reversible interactions with other proteins remain modestly examined. Here, we show the development and validation of a protein nanopore for the detection and quantification of WD40 repeat protein 5 (WDR5), a chromatin-associated hub involved in epigenetic regulation of histone methylation. Our nanopore sensor is equipped with a 14-residue Win motif of mixed lineage leukemia 4 methyltransferase (MLL4Win), a WDR5 ligand. Our approach reveals a broad dynamic range of MLL4Win-WDR5 interactions and three distant subpopulations of binding events, representing three modes of protein recognition. The three binding events are confirmed as specific interactions using a weakly binding WDR5 derivative and various environmental contexts. These outcomes demonstrate the substantial sensitivity of our nanopore sensor, which can be utilized in protein analytics. Nanopores are powerful tools for sampling protein-peptide interactions. Here, the authors convert a protein-based nanopore into a sensitive biosensor to characterize the complex binding of WDR5 protein to a 14-residue ligand.
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9
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Wang X, Zhang H, Douglas JF. The initiation of shear band formation in deformed metallic glasses from soft localized domains. J Chem Phys 2021; 155:204504. [PMID: 34852471 DOI: 10.1063/5.0069729] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
It has long been thought that shear band (SB) formation in amorphous solids initiates from relatively "soft" regions in the material in which large-scale non-affine deformations become localized. The test of this hypothesis requires an effective means of identifying "soft" regions and their evolution as the material is deformed to varying degrees, where the metric of "softness" must also account for the effect of temperature on local material stiffness. We show that the mean square atomic displacement on a caging timescale ⟨u2⟩, the "Debye-Waller factor," provides a useful method for estimating the shear modulus of the entire material and, by extension, the material stiffness at an atomic scale. Based on this "softness" metrology, we observe that SB formation indeed occurs through the strain-induced formation of localized soft regions in our deformed metallic glass free-standing films. Unexpectedly, the critical strain condition for SB formation occurs when the softness (⟨u2⟩) distribution within the emerging soft regions approaches that of the interfacial region in its undeformed state, initiating an instability with similarities to the transition to turbulence. Correspondingly, no SBs arise when the material is so thin that the entire material can be approximately described as being "interfacial" in nature. We also quantify relaxation in the glass and the nature and origin of highly non-Gaussian particle displacements in the dynamically heterogeneous SB regions at times longer than the caging time.
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Affiliation(s)
- Xinyi Wang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
| | - Hao Zhang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
| | - Jack F Douglas
- Material Measurement Laboratory, Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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10
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Larimi MG, Ha JH, Loh SN, Movileanu L. Insertion state of modular protein nanopores into a membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183570. [PMID: 33529578 DOI: 10.1016/j.bbamem.2021.183570] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 01/06/2021] [Accepted: 01/13/2021] [Indexed: 01/04/2023]
Abstract
In the past decade, significant progress has been made in the development of new protein nanopores. Despite these advancements, there is a pressing need for the creation of nanopores equipped with relatively large functional groups for the sampling of biomolecular events on their extramembranous side. Here, we designed, produced, and analyzed protein nanopores encompassing a robust truncation of a monomeric β-barrel membrane protein. An exogenous stably folded protein was anchored within the aqueous phase via a flexible peptide tether of varying length. We have extensively examined the pore-forming properties of these modular protein nanopores using protein engineering and single-molecule electrophysiology. This study revealed distinctions in the nanopore conductance and current fluctuations that arose from tethering the exogenous protein to either the N terminus or the C terminus. Remarkably, these nanopores insert into a planar lipid membrane with one specific conductance among a set of three substate conductance values. Moreover, we demonstrate that the occurrence probabilities of these insertion substates depend on the length of the peptide tether, the orientation of the exogenous protein with respect to the nanopore opening, and the molecular mass of tethered protein. In addition, the three conductance values remain unaltered by major changes in the composition of modular nanopores. The outcomes of this work serve as a platform for further developments in areas of protein engineering of transmembrane pores and biosensor technology.
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Affiliation(s)
| | - Jeung-Hoi Ha
- Department of Biochemistry and Molecular Biology, State University of New York - Upstate Medical University, 4249 Weiskotten Hall, 766 Irving Avenue, Syracuse, NY 13210, USA
| | - Stewart N Loh
- Department of Biochemistry and Molecular Biology, State University of New York - Upstate Medical University, 4249 Weiskotten Hall, 766 Irving Avenue, Syracuse, NY 13210, USA
| | - Liviu Movileanu
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY 13244-1130, USA; Department of Biomedical and Chemical Engineering, Syracuse University, 329 Link Hall, Syracuse, NY 13244, USA.
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