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Garg V, Mathew R, Ibrahim R, Singh K, Ghosh SK. Crowding induced switching of polymer translocation by the amalgamation of entropy and osmotic pressure. iScience 2024; 27:109348. [PMID: 38523793 PMCID: PMC10959672 DOI: 10.1016/j.isci.2024.109348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 01/29/2024] [Accepted: 02/23/2024] [Indexed: 03/26/2024] Open
Abstract
The translocation of polymers is omnipresent in inherently crowded biological systems. We investigate the dynamics of polymer translocation through a pore in free and crowded environments using Langevin dynamics simulation. We observed a location-dependent translocation rate of monomers showcasing counterintuitive behavior in stark contrast to the bead velocity along the polymer backbone. The free energy calculation of asymmetrically placed polymers indicates a critical number of segments to direct receiver-side translocation. For one-sided crowding, we have identified a critical crowding size revealing a nonzero probability of translocation toward the crowded-side. Moreover, we have observed that shifting the polymer toward the crowded-side compensates for one-sided crowding, yielding an equal probability akin to a crowder-free system. In two-sided crowding, a slight variation in crowder size and packing fraction induces a polymer to switch its translocation direction. These conspicuous yet counter-intuitive phenomena are rationalized by minimalistic theoretical arguments based on osmotic pressure and radial entropic forces.
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Affiliation(s)
- Vrinda Garg
- Department of Physics, National Institute of Technology, Warangal 506004, India
| | - Rejoy Mathew
- Department of Physics, National Institute of Technology, Warangal 506004, India
| | - Riyan Ibrahim
- Department of Physics, National Institute of Technology, Warangal 506004, India
| | - Kulveer Singh
- Department of Physics, National Institute of Technology, Warangal 506004, India
| | - Surya K. Ghosh
- Department of Physics, National Institute of Technology, Warangal 506004, India
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Lucas FLR, Finol-Urdaneta RK, Van Thillo T, McArthur JR, van der Heide NJ, Maglia G, Dedecker P, Strauss O, Wloka C. Evidence of Cytolysin A nanopore incorporation in mammalian cells assessed by a graphical user interface. NANOSCALE 2023; 15:16914-16923. [PMID: 37853831 DOI: 10.1039/d3nr01977b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
Technologies capable of assessing cellular metabolites with high precision and temporal resolution are currently limited. Recent developments in the field of nanopore sensors allow the non-stochastic quantification of metabolites, where a nanopore is acting as an electrical transducer for selective substrate binding proteins (SBPs). Here we show that incorporation of the pore-forming toxin Cytolysin A (ClyA) into the plasma membrane of Chinese hamster ovary cells (CHO-K1) results in the appearance of single-channel conductance amenable to multiplexed automated patch-clamp (APC) electrophysiology. In CHO-K1 cells, SBPs modify the ionic current flowing though ClyA nanopores, thus demonstrating its potential for metabolite sensing of living cells. Moreover, we developed a graphical user interface for the analysis of the complex signals resulting from multiplexed APC recordings. This system lays the foundation to bridge the gap between recent advances in the nanopore field (e.g., proteomic and transcriptomic) and potential cellular applications.
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Affiliation(s)
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
- Electrophysiology Facility for Cell Phenotyping and Drug Discovery, Wollongong, NSW 2522, Australia
- Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Toon Van Thillo
- Lab for Nanobiology, Department of Chemistry, KU Leuven, Belgium.
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
- Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Nieck Jordy van der Heide
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, 9747 AG, Groningen, The Netherlands
| | - Giovanni Maglia
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, 9747 AG, Groningen, The Netherlands
| | - Peter Dedecker
- Lab for Nanobiology, Department of Chemistry, KU Leuven, Belgium.
| | - Olaf Strauss
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, A Corporate Member of Freie Universität, Humboldt-University, The Berlin Institute of Health, Berlin, Germany.
| | - Carsten Wloka
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, A Corporate Member of Freie Universität, Humboldt-University, The Berlin Institute of Health, Berlin, Germany.
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Dematties D, Wen C, Zhang SL. A Generalized Transformer-Based Pulse Detection Algorithm. ACS Sens 2022; 7:2710-2720. [PMID: 36039873 PMCID: PMC9513795 DOI: 10.1021/acssensors.2c01218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Pulse-like signals are ubiquitous in the field of single molecule analysis, e.g., electrical or optical pulses caused by analyte translocations in nanopores. The primary challenge in processing pulse-like signals is to capture the pulses in noisy backgrounds, but current methods are subjectively based on a user-defined threshold for pulse recognition. Here, we propose a generalized machine-learning based method, named pulse detection transformer (PETR), for pulse detection. PETR determines the start and end time points of individual pulses, thereby singling out pulse segments in a time-sequential trace. It is objective without needing to specify any threshold. It provides a generalized interface for downstream algorithms for specific application scenarios. PETR is validated using both simulated and experimental nanopore translocation data. It returns a competitive performance in detecting pulses through assessing them with several standard metrics. Finally, the generalization nature of the PETR output is demonstrated using two representative algorithms for feature extraction.
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Affiliation(s)
- Dario Dematties
- Northwestern
Argonne Institute of Science and Engineering, Northwestern University, 2205 Tech Drive Suite 1-160, Evanston, 60208 Illinois, United States,Mathematics
and Computer Science Division, Argonne National
Laboratory, 9700 S. Cass
Avenue, Lemont, 60439 Illinois, United States
| | - Chenyu Wen
- NanoDynamicsLab,
Laboratory of Biophysics, Wageningen University, Stippeneng 4, Wageningen 6708 WE, The
Netherlands,Department
of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, Delft 2629 HZ, The Netherlands
| | - Shi-Li Zhang
- Department
of Electrical Engineering, Uppsala University, Lägerhyddsvägen 1,
752 37, SE-751 03 Uppsala, Sweden,
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