1
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Zhang M, Chen C, Zhang Y, Geng J. Biological nanopores for sensing applications. Proteins 2022; 90:1786-1799. [PMID: 35092317 DOI: 10.1002/prot.26308] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/27/2021] [Accepted: 01/27/2022] [Indexed: 02/05/2023]
Abstract
Biological nanopores are proteins with transmembrane pore that can be embedded in lipid bilayer. With the development of single-channel current measurement technologies, biological nanopores have been reconstituted into planar lipid bilayer and used for single-molecule sensing of various analytes and events such as single-molecule DNA sensing and sequencing. To improve the sensitivity for specific analytes, various engineered nanopore proteins and strategies are deployed. Here, we introduce the origin and principle of nanopore sensing technology as well as the structure and associated properties of frequently used protein nanopores. Furthermore, sensing strategies for different applications are reviewed, with focus on the alteration of buffer condition, protein engineering, and deployment of accessory proteins and adapter-assisted sensing. Finally, outlooks for de novo design of nanopore and nanopore beyond sensing are discussed.
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Affiliation(s)
- Ming Zhang
- Department of Laboratory Medicine, Med-X Center for Manufacturing, West China Hospital, Sichuan University, Chengdu, China
| | - Chen Chen
- Department of Laboratory Medicine, Med-X Center for Manufacturing, West China Hospital, Sichuan University, Chengdu, China
| | - Yanjing Zhang
- Department of Laboratory Medicine, Med-X Center for Manufacturing, West China Hospital, Sichuan University, Chengdu, China
| | - Jia Geng
- Department of Laboratory Medicine, Med-X Center for Manufacturing, West China Hospital, Sichuan University, Chengdu, China
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2
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Cazimoglu I, Booth MJ, Bayley H. A Lipid-Based Droplet Processor for Parallel Chemical Signals. ACS NANO 2021; 15:20214-20224. [PMID: 34788543 PMCID: PMC8717631 DOI: 10.1021/acsnano.1c08217] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 10/08/2021] [Indexed: 05/19/2023]
Abstract
A key goal of bottom-up synthetic biology is to construct cell- and tissue-like structures. Underpinning cellular life is the ability to process several external chemical signals, often in parallel. Until now, cell- and tissue-like structures have been constructed with no more than one signaling pathway. Many pathways rely on signal transport across membranes using protein nanopores. However, such systems currently suffer from the slow transport of molecules. We have optimized the application of these nanopores to permit fast molecular transport, which has allowed us to construct a processor for parallel chemical signals from the bottom up in a modular fashion. The processor comprises three aqueous droplet compartments connected by lipid bilayers and operates in an aqueous environment. It can receive two chemical signals from the external environment, process them orthogonally, and then produce a distinct output for each signal. It is suitable for both sensing and enzymatic processing of environmental signals, with fluorescence and molecular outputs. In the future, such processors could serve as smart drug delivery vehicles or as modules within synthetic tissues to control their behavior in response to external chemical signals.
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3
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Crnković A, Srnko M, Anderluh G. Biological Nanopores: Engineering on Demand. Life (Basel) 2021; 11:life11010027. [PMID: 33466427 PMCID: PMC7824896 DOI: 10.3390/life11010027] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/24/2020] [Accepted: 12/31/2020] [Indexed: 12/17/2022] Open
Abstract
Nanopore-based sensing is a powerful technique for the detection of diverse organic and inorganic molecules, long-read sequencing of nucleic acids, and single-molecule analyses of enzymatic reactions. Selected from natural sources, protein-based nanopores enable rapid, label-free detection of analytes. Furthermore, these proteins are easy to produce, form pores with defined sizes, and can be easily manipulated with standard molecular biology techniques. The range of possible analytes can be extended by using externally added adapter molecules. Here, we provide an overview of current nanopore applications with a focus on engineering strategies and solutions.
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4
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Wilson JW, Rolland AD, Klausen GM, Prell JS. Ion Mobility-Mass Spectrometry Reveals That α-Hemolysin from Staphylococcus aureus Simultaneously Forms Hexameric and Heptameric Complexes in Detergent Micelle Solutions. Anal Chem 2019; 91:10204-10211. [PMID: 31282652 DOI: 10.1021/acs.analchem.9b02243] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Many soluble and membrane proteins form symmetrical homooligomeric complexes. However, determining the oligomeric state of protein complexes can be difficult. Alpha-hemolysin (αHL) from Staphylococcus aureus is a symmetrical homooligomeric protein toxin that forms transmembrane β-barrel pores in host cell membranes. The stable pore structure of αHL has also been exploited in vitro as a nanopore tool. Early structural experiments suggested αHL forms a hexameric pore, while more recent X-ray crystal structure and solution studies have identified a heptameric pore structure. Here, using native ion mobility-mass spectrometry (IM-MS) we find that αHL simultaneously forms hexameric and heptameric oligomers in both tetraethylene glycol monooctyl ether (C8E4) and tetradecylphosphocholine (FOS-14) detergent solutions. We also analyze intact detergent micelle-embedded αHL porelike complexes by native IM-MS without the need to fully strip the detergent micelle, which can cause significant gas-phase unfolding. The highly congested native mass spectra are deconvolved using Fourier- and Gábor-transform (FT and GT) methods to determine charge states and detergent stoichiometry distributions. The intact αHL micelle complexes are found to contain oligomeric state-proportional numbers of detergent molecules. This evidence, combined with IM data and results from vacuum molecular dynamics simulations, is consistent with both the hexamer and the heptamer forming porelike complexes. The ability of αHL to form both oligomeric states simultaneously has implications for its use as a nanopore tool and its pore formation mechanism in vivo. This study also demonstrates more generally the power of FT and GT to deconvolve the charge state and stoichiometry distributions of polydisperse ions.
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Affiliation(s)
- Jesse W Wilson
- Department of Chemistry and Biochemistry , University of Oregon , 1253 University of Oregon , Eugene , Oregon 97403-1253 , United States
| | - Amber D Rolland
- Department of Chemistry and Biochemistry , University of Oregon , 1253 University of Oregon , Eugene , Oregon 97403-1253 , United States
| | - Grant M Klausen
- Department of Chemistry and Biochemistry , University of Oregon , 1253 University of Oregon , Eugene , Oregon 97403-1253 , United States
| | - James S Prell
- Department of Chemistry and Biochemistry , University of Oregon , 1253 University of Oregon , Eugene , Oregon 97403-1253 , United States.,Materials Science Institute , University of Oregon , 1252 University of Oregon , Eugene , Oregon 97403-1252 , United States
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5
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Koo S, Cheley S, Bayley H. Redirecting Pore Assembly of Staphylococcal α-Hemolysin by Protein Engineering. ACS CENTRAL SCIENCE 2019; 5:629-639. [PMID: 31041382 PMCID: PMC6487460 DOI: 10.1021/acscentsci.8b00910] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Indexed: 05/03/2023]
Abstract
α-Hemolysin (αHL), a β-barrel pore-forming toxin (βPFT), is secreted as a water-soluble monomer by Staphylococcus aureus. Upon binding to receptors on target cell membranes, αHL assembles to form heptameric membrane-spanning pores. We have previously engineered αHL to create a protease-activatable toxin that is activated by site-specific proteolysis including by tumor proteases. In this study, we redesigned αHL so that it requires 2-fold activation on target cells through (i) binding to specific receptors, and (ii) extracellular proteolytic cleavage. To assess our strategy, we constructed a fusion protein of αHL with galectin-1 (αHLG1, αHL-Galectin-1 chimera). αHLG1 was cytolytic toward cells that lack a receptor for wild-type αHL. We then constructed protease-activatable mutants of αHLG1 (PAMαHLG1s). PAMαHLG1s were activated by matrix metalloproteinase 2 (MMP-2) and had approximately 50-fold higher cytolytic activity toward MMP-2 overexpressing cells (HT-1080 cells) than toward non-overexpressing cells (HL-60 cells). Our approach provides a novel strategy for tailoring pore-forming toxins for therapeutic applications.
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Affiliation(s)
- Sunwoo Koo
- Department
of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center, 8447 Riverside Parkway, Bryan, Texas 77807, United States
- E-mail: . Phone: 1-979-436-0381
| | - Stephen Cheley
- Department
of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, T6G 2E1 Alberta, Canada
| | - Hagan Bayley
- Department
of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield
Road, Oxford, OX1 3TA England, United Kingdom
- E-mail: . Phone: +44 1865 285101
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6
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Du Y, Liu L, Zhang C, Zhang Y. Two residues in Staphylococcus aureus α-hemolysin related to hemolysis and self-assembly. Infect Drug Resist 2018; 11:1271-1274. [PMID: 30174449 PMCID: PMC6110284 DOI: 10.2147/idr.s167779] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Staphylococcus aureus is becoming increasingly intractable because of its ability to acquire antimicrobial resistance and secrete numerous virulence factors that can exacerbate inflammation. Alpha-hemolysin (Hla) is a pore-forming virulence factor produced by S. aureus that can self-assemble into heptameric mushroom-structured pores in target cell membranes, leading to cell lysis and death. In the present study, we sought to better understand the mechanism underlying hemolysis and the oligomerization of Hla by creating nine mutants with single amino acid changes in different positions of the Hla protein: N17C, T18C, P103C, N105C, M113C, T117C, N121C, D128C, and T129C. The results showed that the P103C and N105C mutations, which are located in the triangle region, significantly diminished hemolysis and heptamer formation when compared with the wild-type Hla protein. This suggests that the P103 and N105 residues play key roles in the assembly of the Hla pore. These results improve our understanding of the mechanism underlying the pore-forming ability of Hla.
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Affiliation(s)
- Yufeng Du
- College of Life Sciences, Northwest University, Xi'an 710069, China,
| | - Li Liu
- Ultrasonic Diagnosis Department, Shaanxi Provincial People's Hospital, Xi'an 710068, China
| | - Chunping Zhang
- College of Chemistry and Material Science, Northwest University, Xi'an 710069, China
| | - Yani Zhang
- College of Life Sciences, Northwest University, Xi'an 710069, China,
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7
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Spruijt E, Tusk SE, Bayley H. DNA scaffolds support stable and uniform peptide nanopores. NATURE NANOTECHNOLOGY 2018; 13:739-745. [PMID: 29808001 DOI: 10.1038/s41565-018-0139-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 04/04/2018] [Indexed: 05/18/2023]
Abstract
The assembly of peptides into membrane-spanning nanopores might be promoted by scaffolds to pre-organize the structures. Such scaffolds could enable the construction of uniform pores of various sizes and pores with controlled permutations around a central axis. Here, we show that DNA nanostructures can serve as scaffolds to arrange peptides derived from the octameric polysaccharide transporter Wza to form uniform nanopores in planar lipid bilayers. Our ring-shaped DNA scaffold is assembled from short synthetic oligonucleotides that are connected to Wza peptides through flexible linkers. When scaffolded, the Wza peptides form conducting nanopores of which only octamers are stable and of uniform conductance. Removal of the DNA scaffold by cleavage of the linkers leads to a rapid loss of the nanopores from the lipid bilayer, which shows that the scaffold is essential for their stability. The DNA scaffold also adds functionality to the nanopores by enabling reversible and permanent binding of complementary tagged oligonucleotides near the nanopore entrance.
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Affiliation(s)
- Evan Spruijt
- Chemistry Research Laboratory, University of Oxford, Oxford, UK.
- Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands.
| | - Samuel E Tusk
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, UK
| | - Hagan Bayley
- Chemistry Research Laboratory, University of Oxford, Oxford, UK.
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8
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Wang S, Zhao Z, Haque F, Guo P. Engineering of protein nanopores for sequencing, chemical or protein sensing and disease diagnosis. Curr Opin Biotechnol 2017; 51:80-89. [PMID: 29232619 DOI: 10.1016/j.copbio.2017.11.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 11/06/2017] [Accepted: 11/07/2017] [Indexed: 11/17/2022]
Abstract
Biological systems contain highly-ordered structures performing diverse functions. The elegant structures of biomachines have inspired the development of nanopores as single molecule sensors. Over the years, the utility of nanopores for detecting a wide variety of analytes have rapidly emerged for sensing, sequencing and diagnostic applications. Several protein channels with diverse shapes and sizes, such as motor channels from bacteriophage Phi29, SPP1, T3, and T4, as well as α-hemolysin, MspA, aerolysin, FluA, OmpF/G, CsgG, ClyA, have been continually investigated and developed as nanopores. Herein, we focus on advances in biological nanopores for single molecule sensing and DNA sequencing from a protein engineering standpoint for changing pore sizes, altering charge distributions, enhancing sensitivity, improving stability, and imparting new detection capabilities.
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Affiliation(s)
| | - Zhengyi Zhao
- Nanobio Delivery Pharmaceutical Co. Ltd., Columbus, OH, USA
| | | | - Peixuan Guo
- College of Pharmacy, Division of Pharmaceutics & Pharmaceutical Chemistry, The Ohio State University, Columbus, OH, USA; College of Medicine, Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA; Center for RNA Nanobiotechnology and Nanomedicine, The Ohio State University, Columbus, OH, USA.
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9
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Zhang H, Hiratani M, Nagaoka K, Kawano R. MicroRNA detection at femtomolar concentrations with isothermal amplification and a biological nanopore. NANOSCALE 2017; 9:16124-16127. [PMID: 29043339 DOI: 10.1039/c7nr04215a] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
One of the greatest challenges faced by chemists and biologists is the detection of molecules at extremely low concentrations. This paper describes a method to detect ultra-low concentrations (1 femtomole) of nucleotides using isothermal amplification and a biological nanopore.
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Affiliation(s)
- Haolin Zhang
- Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
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10
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Ayub M, Bayley H. Engineered transmembrane pores. Curr Opin Chem Biol 2016; 34:117-126. [PMID: 27658267 DOI: 10.1016/j.cbpa.2016.08.005] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 08/09/2016] [Accepted: 08/10/2016] [Indexed: 12/15/2022]
Abstract
Today, hundreds of researchers are working on nanopores, making an impact in both basic science and biotechnology. Proteins remain the most versatile sources of nanopores, based on our ability to engineer them with sub-nanometer precision. Recent work aimed at the construction and discovery of novel pores has included unnatural amino acid mutagenesis and the application of selection techniques. The diversity of structures has now been increased through the development of helix-based pores as well as the better-known β barrels. New developments also include truncated pores, which pierce bilayers through lipid rearrangement, and hybrid pores, which do away with bilayers altogether. Pore dimers, which span two lipid bilayers, have been constructed and pores based on DNA nanostructures are gaining in importance. While nanopore DNA sequencing has received enthusiastic attention, protein pores have a wider range of potential applications, requiring specifications that will require engineering efforts to continue for years to come.
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Affiliation(s)
- Mariam Ayub
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Hagan Bayley
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom.
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11
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Clamer M, Höfler L, Mikhailova E, Viero G, Bayley H. Detection of 3'-end RNA uridylation with a protein nanopore. ACS NANO 2014; 8:1364-74. [PMID: 24369707 PMCID: PMC3936189 DOI: 10.1021/nn4050479] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Post-transcriptional modifications of the 3'-ends of RNA molecules have a profound impact on their stability and processing in the cell. Uridylation, the addition of uridines to 3'-ends, has recently been found to be an important regulatory signal to stabilize the tagged molecules or to direct them toward degradation. Simple and cost-effective methods for the detection of this post-transcriptional modification are not yet available. Here, we demonstrate the selective and transient binding of 3'-uridylated ssRNAs inside the β barrel of the staphylococcal α-hemolysin (αHL) nanopore and investigate the molecular basis of uridine recognition by the pore. We show the discrimination of 3'-oligouridine tails on the basis of their lengths and propose the αHL nanopore as a useful sensor for this biologically relevant RNA modification.
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Affiliation(s)
- Massimiliano Clamer
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
- Laboratory of Translational Genomics, Center for Integrative Biology, University of Trento, Via delle Regole, 101 38123 Mattarello (TN), Italy
| | - Lajos Höfler
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Ellina Mikhailova
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Gabriella Viero
- Laboratory of Translational Genomics, Center for Integrative Biology, University of Trento, Via delle Regole, 101 38123 Mattarello (TN), Italy
- Institute of Biophysics, CNR, Via alla Cascata 56/C, 38123 (Povo) Trento, Italy
| | - Hagan Bayley
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
- Corresponding Author: Hagan Bayley
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12
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Sherman MP, Minnerly J, Curtiss W, Rangwala S, Kelley ST. Research on neonatal microbiomes: what neonatologists need to know. Neonatology 2014; 105:14-24. [PMID: 24193200 PMCID: PMC3903415 DOI: 10.1159/000354944] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 08/06/2013] [Indexed: 01/08/2023]
Abstract
The aim of this article is to educate neonatal caregivers about metagenomics. This scientific field uses novel and ever changing molecular methods to identify how infants become colonized with microbes after birth. Publications using metagenomics appear infrequently in the neonatal literature because clinicians are unaccustomed to the analytical techniques, data interpretation, and illustration of the results. This review covers those areas. After a brief introduction of neonatal citations forthcoming from metagenomic studies, the following topics are covered: (1) the history of metagenomics, (2) a description of current and emerging instruments used to define microbial populations in human organs, and (3) how extensive databases generated by genome analyzers are examined and presented to readers. Clinicians may feel like they are learning a new language; however, they will appreciate this task is essential to understanding and practicing neonatal medicine in the future.
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Affiliation(s)
- Michael P Sherman
- Department of Child Health, University of Missouri, Columbia, Mo., USA
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13
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Affiliation(s)
| | - Sergey M. Bezrukov
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, U.S.A
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14
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Affiliation(s)
- Stephen M. Oja
- Department of Chemistry, University of Washington, Seattle, Washington 98195,
United States
| | - Marissa Wood
- Department of Chemistry, University of Washington, Seattle, Washington 98195,
United States
| | - Bo Zhang
- Department of Chemistry, University of Washington, Seattle, Washington 98195,
United States
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15
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Abstract
Proteins are the work-horses of life and excute the essential processes involved in the growth and repair of cells. These roles include all aspects of cell signalling, metabolism and repair that allow living things to exist. They are not only chemical catalysts and machine components, they are also structural components of the cell or organism, capable of self-organisation into strong supramolecular cages, fibres and meshes. How proteins are encoded genetically and how they are sythesised in vivo is now well understood, and for an increasing number of proteins, the relationship between structure and function is known in exquisite detail. The next challenge in bionanoscience is to adapt useful protein systems to build new functional structures. Well-defined natural structures with potential useful shapes are a good starting point. With this in mind, in this chapter we discuss the properties of natural and artificial protein channels, nanotubes and cages with regard to recent progress and potential future applications. Chemistries for attaching together different proteins to form superstructures are considered as well as the difficulties associated with designing complex protein structures ab initio.
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Affiliation(s)
- Jonathan G. Heddle
- Heddle Initiative Research Unit RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
| | - Jeremy R. H. Tame
- Protein Design Laboratory Yokohama City University 1-7—29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045 Japan
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16
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Pavlenok M, Derrington IM, Gundlach JH, Niederweis M. MspA nanopores from subunit dimers. PLoS One 2012; 7:e38726. [PMID: 22719928 PMCID: PMC3377714 DOI: 10.1371/journal.pone.0038726] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 05/14/2012] [Indexed: 11/19/2022] Open
Abstract
Mycobacterium smegmatis porin A (MspA) forms an octameric channel and represents the founding member of a new family of pore proteins. Control of subunit stoichiometry is important to tailor MspA for nanotechnological applications. In this study, two MspA monomers were connected by linkers ranging from 17 to 62 amino acids in length. The oligomeric pore proteins were purified from M. smegmatis and were shown to form functional channels in lipid bilayer experiments. These results indicated that the peptide linkers did not prohibit correct folding and localization of MspA. However, expression levels were reduced by 10-fold compared to wild-type MspA. MspA is ideal for nanopore sequencing due to its unique pore geometry and its robustness. To assess the usefulness of MspA made from dimeric subunits for DNA sequencing, we linked two M1-MspA monomers, whose constriction zones were modified to enable DNA translocation. Lipid bilayer experiments demonstrated that this construct also formed functional channels. Voltage gating of MspA pores made from M1 monomers and M1-M1 dimers was identical indicating similar structural and dynamic channel properties. Glucose uptake in M. smegmatis cells lacking porins was restored by expressing the dimeric mspA M1 gene indicating correct folding and localization of M1-M1 pores in their native membrane. Single-stranded DNA hairpins produced identical ionic current blockades in pores made from monomers and subunit dimers demonstrating that M1-M1 pores are suitable for DNA sequencing. This study provides the proof of principle that production of single-chain MspA pores in M. smegmatis is feasible and paves the way for generating MspA pores with altered stoichiometries. Subunit dimers enable better control of the chemical and physical properties of the constriction zone of MspA. This approach will be valuable both in understanding transport across the outer membrane in mycobacteria and in tailoring MspA for nanopore sequencing of DNA.
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Affiliation(s)
- Mikhail Pavlenok
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Ian M. Derrington
- Department of Physics, University of Washington, Seattle, Washington, United States of America
| | - Jens H. Gundlach
- Department of Physics, University of Washington, Seattle, Washington, United States of America
| | - Michael Niederweis
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- * E-mail:
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