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Pavlenok M, Nair RR, Hendrickson RC, Niederweis M. The C-terminus is essential for the stability of the mycobacterial channel protein MspA. Protein Sci 2024; 33:e4912. [PMID: 38358254 PMCID: PMC10868439 DOI: 10.1002/pro.4912] [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: 06/26/2023] [Revised: 12/15/2023] [Accepted: 01/10/2024] [Indexed: 02/16/2024]
Abstract
Outer membrane proteins perform essential functions in uptake and secretion processes in bacteria. MspA is an octameric channel protein in the outer membrane of Mycobacterium smegmatis and is structurally distinct from any other known outer membrane protein. MspA is the founding member of a family with more than 3000 homologs and is one of the most widely used proteins in nanotechnological applications due to its advantageous pore structure and extraordinary stability. While a conserved C-terminal signal sequence is essential for folding and protein assembly in the outer membrane of Gram-negative bacteria, the molecular determinants of these processes are unknown for MspA. In this study, we show that mutation and deletion of methionine 183 in the highly conserved C-terminus of MspA and mutation of the conserved tryptophan 40 lead to a complete loss of protein in heat extracts of M. smegmatis. Swapping these residues partially restores the heat stability of MspA indicating that methionine 183 and tryptophan 40 form a conserved sulfur-π electron interaction, which stabilizes the MspA monomer. Flow cytometry showed that all MspA mutants are surface-accessible demonstrating that oligomerization and membrane integration in M. smegmatis are not affected. Thus, the conserved C-terminus of MspA is essential for its thermal stability, but it is not required for protein assembly in its native membrane, indicating that this process is mediated by a mechanism distinct from that in Gram-negative bacteria. These findings will benefit the rational design of MspA-like pores to tailor their properties in current and future applications.
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Affiliation(s)
- Mikhail Pavlenok
- Department of MicrobiologyUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | | | | | - Michael Niederweis
- Department of MicrobiologyUniversity of Alabama at BirminghamBirminghamAlabamaUSA
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2
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Wei X, Penkauskas T, Reiner JE, Kennard C, Uline MJ, Wang Q, Li S, Aksimentiev A, Robertson JW, Liu C. Engineering Biological Nanopore Approaches toward Protein Sequencing. ACS NANO 2023; 17:16369-16395. [PMID: 37490313 PMCID: PMC10676712 DOI: 10.1021/acsnano.3c05628] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
Biotechnological innovations have vastly improved the capacity to perform large-scale protein studies, while the methods we have for identifying and quantifying individual proteins are still inadequate to perform protein sequencing at the single-molecule level. Nanopore-inspired systems devoted to understanding how single molecules behave have been extensively developed for applications in genome sequencing. These nanopore systems are emerging as prominent tools for protein identification, detection, and analysis, suggesting realistic prospects for novel protein sequencing. This review summarizes recent advances in biological nanopore sensors toward protein sequencing, from the identification of individual amino acids to the controlled translocation of peptides and proteins, with attention focused on device and algorithm development and the delineation of molecular mechanisms with the aid of simulations. Specifically, the review aims to offer recommendations for the advancement of nanopore-based protein sequencing from an engineering perspective, highlighting the need for collaborative efforts across multiple disciplines. These efforts should include chemical conjugation, protein engineering, molecular simulation, machine-learning-assisted identification, and electronic device fabrication to enable practical implementation in real-world scenarios.
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Affiliation(s)
- Xiaojun Wei
- Biomedical Engineering Program, University of South Carolina, Columbia, SC 29208, United States
- Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208, United States
| | - Tadas Penkauskas
- Biophysics and Biomedical Measurement Group, Microsystems and Nanotechnology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States
- School of Engineering, Brown University, Providence, RI 02912, United States
| | - Joseph E. Reiner
- Department of Physics, Virginia Commonwealth University, Richmond, VA 23284, United States
| | - Celeste Kennard
- Biomedical Engineering Program, University of South Carolina, Columbia, SC 29208, United States
| | - Mark J. Uline
- Biomedical Engineering Program, University of South Carolina, Columbia, SC 29208, United States
- Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208, United States
| | - Qian Wang
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, United States
| | - Sheng Li
- School of Data Science, University of Virginia, Charlottesville, VA 22903, United States
| | - Aleksei Aksimentiev
- Department of Physics and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Joseph W.F. Robertson
- Biophysics and Biomedical Measurement Group, Microsystems and Nanotechnology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States
| | - Chang Liu
- Biomedical Engineering Program, University of South Carolina, Columbia, SC 29208, United States
- Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208, United States
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Yu L, Kang X, Li F, Mehrafrooz B, Makhamreh A, Fallahi A, Foster JC, Aksimentiev A, Chen M, Wanunu M. Unidirectional single-file transport of full-length proteins through a nanopore. Nat Biotechnol 2023; 41:1130-1139. [PMID: 36624148 PMCID: PMC10329728 DOI: 10.1038/s41587-022-01598-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 11/02/2022] [Indexed: 01/10/2023]
Abstract
The electrical current blockade of a peptide or protein threading through a nanopore can be used as a fingerprint of the molecule in biosensor applications. However, threading of full-length proteins has only been achieved using enzymatic unfolding and translocation. Here we describe an enzyme-free approach for unidirectional, slow transport of full-length proteins through nanopores. We show that the combination of a chemically resistant biological nanopore, α-hemolysin (narrowest part is ~1.4 nm in diameter), and a high concentration guanidinium chloride buffer enables unidirectional, single-file protein transport propelled by an electroosmotic effect. We show that the mean protein translocation velocity depends linearly on the applied voltage and translocation times depend linearly on length, resembling the translocation dynamics of ssDNA. Using a supervised machine-learning classifier, we demonstrate that single-translocation events contain sufficient information to distinguish their threading orientation and identity with accuracies larger than 90%. Capture rates of protein are increased substantially when either a genetically encoded charged peptide tail or a DNA tag is added to a protein.
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Affiliation(s)
- Luning Yu
- Department of Physics, Northeastern University, Boston, MA, USA
| | - Xinqi Kang
- Department of Bioengineering, Northeastern University, Boston, MA, USA
| | - Fanjun Li
- Department of Chemistry, University of Massachusetts at Amherst, Amherst, MA, USA
| | - Behzad Mehrafrooz
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Amr Makhamreh
- Department of Bioengineering, Northeastern University, Boston, MA, USA
| | - Ali Fallahi
- Department of Bioengineering, Northeastern University, Boston, MA, USA
| | - Joshua C Foster
- Molecular and Cellular Biology Program, University of Massachusetts at Amherst, Amherst, MA, USA
| | - Aleksei Aksimentiev
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Min Chen
- Department of Chemistry, University of Massachusetts at Amherst, Amherst, MA, USA
- Molecular and Cellular Biology Program, University of Massachusetts at Amherst, Amherst, MA, USA
| | - Meni Wanunu
- Department of Physics, Northeastern University, Boston, MA, USA.
- Department of Bioengineering, Northeastern University, Boston, MA, USA.
- Chemistry and Chemical Biology, Northeastern University, Boston, MA, USA.
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4
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Straathof S, Di Muccio G, Yelleswarapu M, Alzate Banguero M, Wloka C, van der Heide NJ, Chinappi M, Maglia G. Protein Sizing with 15 nm Conical Biological Nanopore YaxAB. ACS NANO 2023; 17:13685-13699. [PMID: 37458334 PMCID: PMC10373527 DOI: 10.1021/acsnano.3c02847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
Nanopores are promising single-molecule tools for the electrical identification and sequencing of biomolecules. However, the characterization of proteins, especially in real-time and in complex biological samples, is complicated by the sheer variety of sizes and shapes in the proteome. Here, we introduce a large biological nanopore, YaxAB for folded protein analysis. The 15 nm cis-opening and a 3.5 nm trans-constriction describe a conical shape that allows the characterization of a wide range of proteins. Molecular dynamics showed proteins are captured by the electroosmotic flow, and the overall resistance is largely dominated by the narrow trans constriction region of the nanopore. Conveniently, proteins in the 35-125 kDa range remain trapped within the conical lumen of the nanopore for a time that can be tuned by the external bias. Contrary to cylindrical nanopores, in YaxAB, the current blockade decreases with the size of the trapped protein, as smaller proteins penetrate deeper into the constriction region than larger proteins do. These characteristics are especially useful for characterizing large proteins, as shown for pentameric C-reactive protein (125 kDa), a widely used health indicator, which showed a signal that could be identified in the background of other serum proteins.
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Affiliation(s)
- Sabine Straathof
- Groningen Biomolecular Sciences & Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Giovanni Di Muccio
- Department of Industrial Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy
| | - Maaruthy Yelleswarapu
- Groningen Biomolecular Sciences & Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Melissa Alzate Banguero
- Department of Industrial Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy
| | - Carsten Wloka
- Groningen Biomolecular Sciences & Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, A Corporate Member of Freie Universität, Humboldt-University, The Berlin Institute of Health, Berlin 10178, Germany
| | - Nieck Jordy van der Heide
- Groningen Biomolecular Sciences & Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Mauro Chinappi
- Department of Industrial Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy
| | - Giovanni Maglia
- Groningen Biomolecular Sciences & Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands
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5
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A click chemistry amplified nanopore assay for ultrasensitive quantification of HIV-1 p24 antigen in clinical samples. Nat Commun 2022; 13:6852. [PMID: 36369146 PMCID: PMC9651128 DOI: 10.1038/s41467-022-34273-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 10/19/2022] [Indexed: 11/13/2022] Open
Abstract
Despite major advances in HIV testing, ultrasensitive detection of early infection remains challenging, especially for the viral capsid protein p24, which is an early virological biomarker of HIV-1 infection. Here, To improve p24 detection in patients missed by immunological tests that dominate the diagnostics market, we show a click chemistry amplified nanopore (CAN) assay for ultrasensitive quantitative detection. This strategy achieves a 20.8 fM (0.5 pg/ml) limit of detection for HIV-1 p24 antigen in human serum, demonstrating 20~100-fold higher analytical sensitivity than nanocluster-based immunoassays and clinically used enzyme-linked immunosorbent assay, respectively. Clinical validation of the CAN assay in a pilot cohort shows p24 quantification at ultra-low concentration range and correlation with CD4 count and viral load. We believe that this strategy can improve the utility of p24 antigen in detecting early infection and monitoring HIV progression and treatment efficacy, and also can be readily modified to detect other infectious diseases.
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