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  1. Article ; Online: Author Correction: Super-resolved 3D tracking of cargo transport through nuclear pore complexes.

    Chowdhury, Rajdeep / Sau, Abhishek / Musser, Siegfried M

    Nature cell biology

    2022  Volume 24, Issue 3, Page(s) 400

    Language English
    Publishing date 2022-02-01
    Publishing country England
    Document type Published Erratum
    ZDB-ID 1474722-4
    ISSN 1476-4679 ; 1465-7392
    ISSN (online) 1476-4679
    ISSN 1465-7392
    DOI 10.1038/s41556-022-00855-6
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Oligomerization state of the functional bacterial twin-arginine translocation (Tat) receptor complex.

    Sharma, Ankith / Chowdhury, Rajdeep / Musser, Siegfried M

    Communications biology

    2022  Volume 5, Issue 1, Page(s) 988

    Abstract: The twin-arginine translocation (Tat) system transports folded proteins across bacterial and plastid energy transducing membranes. Ion leaks are generally considered to be mitigated by the creation and destruction of the translocation conduit in a cargo- ... ...

    Abstract The twin-arginine translocation (Tat) system transports folded proteins across bacterial and plastid energy transducing membranes. Ion leaks are generally considered to be mitigated by the creation and destruction of the translocation conduit in a cargo-dependent manner, a mechanism that enables tight sealing around a wide range of cargo shapes and sizes. In contrast to the variable stoichiometry of the active translocon, the oligomerization state of the receptor complex is considered more consistently stable but has proved stubbornly difficult to establish. Here, using a single molecule photobleaching analysis of individual inverted membrane vesicles, we demonstrate that Tat receptor complexes are tetrameric in native membranes with respect to both TatB and TatC. This establishes a maximal diameter for a resting state closed pore. A large percentage of Tat-deficient vesicles explains the typically low transport efficiencies observed. This individual reaction chamber approach will facilitate examination of the effects of stochastically distributed molecules.
    MeSH term(s) Arginine/metabolism ; Escherichia coli/genetics ; Escherichia coli/metabolism ; Escherichia coli Proteins/genetics ; Escherichia coli Proteins/metabolism ; Membrane Transport Proteins/genetics ; Membrane Transport Proteins/metabolism ; Protein Transport
    Chemical Substances Escherichia coli Proteins ; Membrane Transport Proteins ; Arginine (94ZLA3W45F)
    Language English
    Publishing date 2022-09-19
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ISSN 2399-3642
    ISSN (online) 2399-3642
    DOI 10.1038/s42003-022-03952-2
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Super-resolved 3D tracking of cargo transport through nuclear pore complexes.

    Chowdhury, Rajdeep / Sau, Abhishek / Musser, Siegfried M

    Nature cell biology

    2022  Volume 24, Issue 1, Page(s) 112–122

    Abstract: Nuclear pore complexes (NPCs) embedded within the nuclear envelope mediate rapid, selective and bidirectional traffic between the cytoplasm and the nucleoplasm. Deciphering the mechanism and dynamics of this process is challenged by the need for high ... ...

    Abstract Nuclear pore complexes (NPCs) embedded within the nuclear envelope mediate rapid, selective and bidirectional traffic between the cytoplasm and the nucleoplasm. Deciphering the mechanism and dynamics of this process is challenged by the need for high spatial and temporal resolution. We report here a multicolour imaging approach that enables direct three-dimensional visualization of cargo transport trajectories relative to a super-resolved octagonal double-ring structure of the NPC scaffold. The success of this approach is enabled by the high positional stability of NPCs within permeabilized cells, as verified by a combined experimental and simulation analysis. Hourglass-shaped translocation conduits for two cargo complexes representing different nuclear transport receptor pathways indicate rapid migration through the permeability barrier on or near the NPC scaffold. Binding sites for cargo complexes extend more than 100 nm from the pore openings, which is consistent with a wide distribution of the phenylalanine-glycine polypeptides that bind nuclear transport receptors.
    MeSH term(s) Active Transport, Cell Nucleus/physiology ; Binding Sites/physiology ; Cell Line, Tumor ; Cell Nucleus/metabolism ; Computational Biology/methods ; Humans ; Imaging, Three-Dimensional/methods ; Nuclear Pore/physiology ; Nuclear Pore Complex Proteins/metabolism ; Single Molecule Imaging
    Chemical Substances Nuclear Pore Complex Proteins
    Language English
    Publishing date 2022-01-10
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 1474722-4
    ISSN 1476-4679 ; 1465-7392
    ISSN (online) 1476-4679
    ISSN 1465-7392
    DOI 10.1038/s41556-021-00815-6
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Tuning axial and lateral localization precision in 3D super-resolution microscopy with variable astigmatism.

    Chowdhury, Rajdeep / Sau, Abhishek / Chao, Jerry / Sharma, Ankith / Musser, Siegfried M

    Optics letters

    2023  Volume 47, Issue 21, Page(s) 5727–5730

    Abstract: Astigmatism imaging is a three-dimensional (3D) single molecule fluorescence microscopy approach that yields super-resolved spatial information on a rapid time scale from a single image. It is ideally suited for resolving structures on a sub-micrometer ... ...

    Abstract Astigmatism imaging is a three-dimensional (3D) single molecule fluorescence microscopy approach that yields super-resolved spatial information on a rapid time scale from a single image. It is ideally suited for resolving structures on a sub-micrometer scale and temporal behavior in the millisecond regime. While traditional astigmatism imaging utilizes a cylindrical lens, adaptive optics enables the astigmatism to be tuned for the experiment. We demonstrate here how the precisions in x, y, and z are inter-linked and vary with the astigmatism, z-position, and photon level. This experimentally driven and verified approach provides a guide for astigmatism selection in biological imaging strategies.
    Language English
    Publishing date 2023-05-23
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4794
    ISSN (online) 1539-4794
    DOI 10.1364/OL.466213
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Influence of the TorD signal peptide chaperone on Tat-dependent protein translocation.

    Bageshwar, Umesh K / DattaGupta, Antara / Musser, Siegfried M

    PloS one

    2021  Volume 16, Issue 9, Page(s) e0256715

    Abstract: The twin-arginine translocation (Tat) pathway transports folded proteins across energetic membranes. Numerous Tat substrates contain co-factors that are inserted before transport with the assistance of redox enzyme maturation proteins (REMPs), which bind ...

    Abstract The twin-arginine translocation (Tat) pathway transports folded proteins across energetic membranes. Numerous Tat substrates contain co-factors that are inserted before transport with the assistance of redox enzyme maturation proteins (REMPs), which bind to the signal peptide of precursor proteins. How signal peptides are transferred from a REMP to a binding site on the Tat receptor complex remains unknown. Since the signal peptide mediates both interactions, possibilities include: i) a coordinated hand-off mechanism; or ii) a diffusional search after REMP dissociation. We investigated the binding interaction between substrates containing the TorA signal peptide (spTorA) and its cognate REMP, TorD, and the effect of TorD on the in vitro transport of such substrates. We found that Escherichia coli TorD is predominantly a monomer at low micromolar concentrations (dimerization KD > 50 μM), and this monomer binds reversibly to spTorA (KD ≈ 1 μM). While TorD binds to membranes (KD ≈ 100 nM), it has no apparent affinity for Tat translocons and it inhibits binding of a precursor substrate to the membrane. TorD has a minimal effect on substrate transport by the Tat system, being mildly inhibitory at high concentrations. These data are consistent with a model in which the REMP-bound signal peptide is shielded from recognition by the Tat translocon, and spontaneous dissociation of the REMP allows the substrate to engage the Tat machinery. Thus, the REMP does not assist with targeting to the Tat translocon, but rather temporarily shields the signal peptide.
    MeSH term(s) Binding Sites/genetics ; Escherichia coli/genetics ; Escherichia coli Proteins/genetics ; Gene Products, tat/genetics ; Molecular Chaperones/genetics ; Oxidoreductases, N-Demethylating/genetics ; Protein Binding/genetics ; Protein Sorting Signals/genetics ; Protein Transport/genetics ; Substrate Specificity ; Twin-Arginine-Translocation System/genetics
    Chemical Substances Escherichia coli Proteins ; Gene Products, tat ; Molecular Chaperones ; Protein Sorting Signals ; TorD protein, E coli ; Twin-Arginine-Translocation System ; Oxidoreductases, N-Demethylating (EC 1.5.-) ; trimethylamine dehydrogenase (EC 1.5.8.2)
    Language English
    Publishing date 2021-09-09
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ISSN 1932-6203
    ISSN (online) 1932-6203
    DOI 10.1371/journal.pone.0256715
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: The Tat protein transport system: intriguing questions and conundrums.

    Hamsanathan, Shruthi / Musser, Siegfried M

    FEMS microbiology letters

    2018  Volume 365, Issue 12

    Abstract: The Tat machinery catalyzes the transport of folded proteins across the cytoplasmic membrane in bacteria and the thylakoid membrane in plants. Transport occurs only in the presence of an electric field (Δψ) and/or a pH (ΔpH) gradient, and thus, Tat ... ...

    Abstract The Tat machinery catalyzes the transport of folded proteins across the cytoplasmic membrane in bacteria and the thylakoid membrane in plants. Transport occurs only in the presence of an electric field (Δψ) and/or a pH (ΔpH) gradient, and thus, Tat transport is considered to be dependent on the proton motive force (pmf). This presents a fundamental and major challenge, namely, that the Tat system catalyzes the movement of large folded protein cargos across a membrane without collapse of ion gradients. Current models argue that the active translocon assembles de novo for each cargo transported, thus providing an effective gating mechanism to minimize ion leakage. A limited structural understanding of the intermediates occurring during transport and the role of the pmf in stabilizing and/or driving this process have hindered the development of more detailed models. A fundamental question that remains unanswered is whether the pmf is actually 'consumed', providing an energetic driving force for transport, or alternatively, whether its presence is instead necessary to provide the appropriate environment for the translocon components to become active. Including addressing this issue in greater detail, we explore a series of additional questions that challenge current models, and, hopefully, motivate future work.
    MeSH term(s) Bacteria/chemistry ; Bacteria/metabolism ; Gene Products, tat/metabolism ; Hydrogen-Ion Concentration ; Membrane Potentials ; Membrane Transport Proteins/metabolism ; Protein Folding ; Protein Sorting Signals ; Protein Transport ; Proton-Motive Force
    Chemical Substances Gene Products, tat ; Membrane Transport Proteins ; Protein Sorting Signals
    Language English
    Publishing date 2018-06-13
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Review
    ZDB-ID 752343-9
    ISSN 1574-6968 ; 0378-1097
    ISSN (online) 1574-6968
    ISSN 0378-1097
    DOI 10.1093/femsle/fny123
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Influence of the TorD signal peptide chaperone on Tat-dependent protein translocation.

    Umesh K Bageshwar / Antara DattaGupta / Siegfried M Musser

    PLoS ONE, Vol 16, Iss 9, p e

    2021  Volume 0256715

    Abstract: The twin-arginine translocation (Tat) pathway transports folded proteins across energetic membranes. Numerous Tat substrates contain co-factors that are inserted before transport with the assistance of redox enzyme maturation proteins (REMPs), which bind ...

    Abstract The twin-arginine translocation (Tat) pathway transports folded proteins across energetic membranes. Numerous Tat substrates contain co-factors that are inserted before transport with the assistance of redox enzyme maturation proteins (REMPs), which bind to the signal peptide of precursor proteins. How signal peptides are transferred from a REMP to a binding site on the Tat receptor complex remains unknown. Since the signal peptide mediates both interactions, possibilities include: i) a coordinated hand-off mechanism; or ii) a diffusional search after REMP dissociation. We investigated the binding interaction between substrates containing the TorA signal peptide (spTorA) and its cognate REMP, TorD, and the effect of TorD on the in vitro transport of such substrates. We found that Escherichia coli TorD is predominantly a monomer at low micromolar concentrations (dimerization KD > 50 μM), and this monomer binds reversibly to spTorA (KD ≈ 1 μM). While TorD binds to membranes (KD ≈ 100 nM), it has no apparent affinity for Tat translocons and it inhibits binding of a precursor substrate to the membrane. TorD has a minimal effect on substrate transport by the Tat system, being mildly inhibitory at high concentrations. These data are consistent with a model in which the REMP-bound signal peptide is shielded from recognition by the Tat translocon, and spontaneous dissociation of the REMP allows the substrate to engage the Tat machinery. Thus, the REMP does not assist with targeting to the Tat translocon, but rather temporarily shields the signal peptide.
    Keywords Medicine ; R ; Science ; Q
    Subject code 571
    Language English
    Publishing date 2021-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Deciphering the Structure and Function of Nuclear Pores Using Single-Molecule Fluorescence Approaches.

    Musser, Siegfried M / Grünwald, David

    Journal of molecular biology

    2016  Volume 428, Issue 10 Pt A, Page(s) 2091–2119

    Abstract: Due to its central role in macromolecular trafficking and nucleocytoplasmic information transfer, the nuclear pore complex (NPC) has been studied in great detail using a wide spectrum of methods. Consequently, many aspects of its architecture, general ... ...

    Abstract Due to its central role in macromolecular trafficking and nucleocytoplasmic information transfer, the nuclear pore complex (NPC) has been studied in great detail using a wide spectrum of methods. Consequently, many aspects of its architecture, general function, and role in the life cycle of a cell are well understood. Over the last decade, fluorescence microscopy methods have enabled the real-time visualization of single molecules interacting with and transiting through the NPC, allowing novel questions to be examined with nanometer precision. While initial single-molecule studies focused primarily on import pathways using permeabilized cells, it has recently proven feasible to investigate the export of mRNAs in living cells. Single-molecule assays can address questions that are difficult or impossible to answer by other means, yet the complexity of nucleocytoplasmic transport requires that interpretation be based on a firm genetic, biochemical, and structural foundation. Moreover, conceptually simple single-molecule experiments remain technically challenging, particularly with regard to signal intensity, signal-to-noise ratio, and the analysis of noise, stochasticity, and precision. We discuss nuclear transport issues recently addressed by single-molecule microscopy, evaluate the limits of existing assays and data, and identify open questions for future studies. We expect that single-molecule fluorescence approaches will continue to be applied to outstanding nucleocytoplasmic transport questions, and that the approaches developed for NPC studies are extendable to additional complex systems and pathways within cells.
    MeSH term(s) Active Transport, Cell Nucleus/physiology ; Fluorescence ; Humans ; Nuclear Pore/metabolism ; Nuclear Pore/physiology ; Nuclear Pore Complex Proteins/metabolism ; Protein Transport/physiology ; RNA, Messenger/metabolism
    Chemical Substances Nuclear Pore Complex Proteins ; RNA, Messenger
    Language English
    Publishing date 2016-03-02
    Publishing country England
    Document type Journal Article ; Review ; Research Support, Non-U.S. Gov't
    ZDB-ID 80229-3
    ISSN 1089-8638 ; 0022-2836
    ISSN (online) 1089-8638
    ISSN 0022-2836
    DOI 10.1016/j.jmb.2016.02.023
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article: The Tat protein transport system: intriguing questions and conundrums

    Hamsanathan, Shruthi / Musser, Siegfried M

    FEMS microbiology letters. 2018 May 21, v. 365, no. 12

    2018  

    Abstract: The Tat machinery catalyzes the transport of folded proteins across the cytoplasmic membrane in bacteria and the thylakoid membrane in plants. Transport occurs only in the presence of an electric field (Δψ) and/or a pH (ΔpH) gradient, and thus, Tat ... ...

    Abstract The Tat machinery catalyzes the transport of folded proteins across the cytoplasmic membrane in bacteria and the thylakoid membrane in plants. Transport occurs only in the presence of an electric field (Δψ) and/or a pH (ΔpH) gradient, and thus, Tat transport is considered to be dependent on the proton motive force (pmf). This presents a fundamental and major challenge, namely, that the Tat system catalyzes the movement of large folded protein cargos across a membrane without collapse of ion gradients. Current models argue that the active translocon assembles de novo for each cargo transported, thus providing an effective gating mechanism to minimize ion leakage. A limited structural understanding of the intermediates occurring during transport and the role of the pmf in stabilizing and/or driving this process have hindered the development of more detailed models. A fundamental question that remains unanswered is whether the pmf is actually ‘consumed’, providing an energetic driving force for transport, or alternatively, whether its presence is instead necessary to provide the appropriate environment for the translocon components to become active. Including addressing this issue in greater detail, we explore a series of additional questions that challenge current models, and, hopefully, motivate future work.
    Keywords bacteria ; catalytic activity ; electric field ; models ; pH ; protein transport ; proteins ; proton-motive force ; thylakoids
    Language English
    Dates of publication 2018-0521
    Publishing place Oxford University Press
    Document type Article
    ZDB-ID 752343-9
    ISSN 1574-6968 ; 0378-1097
    ISSN (online) 1574-6968
    ISSN 0378-1097
    DOI 10.1093/femsle/fny123
    Database NAL-Catalogue (AGRICOLA)

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  10. Article: Deciphering the Structure and Function of Nuclear Pores Using Single-Molecule Fluorescence Approaches

    Musser, Siegfried M / Grünwald, David

    Journal of Molecular Biology. 2016 May 22, v. 428

    2016  

    Abstract: Due to its central role in macromolecular trafficking and nucleocytoplasmic information transfer, the nuclear pore complex (NPC) has been studied in great detail using a wide spectrum of methods. Consequently, many aspects of its architecture, general ... ...

    Abstract Due to its central role in macromolecular trafficking and nucleocytoplasmic information transfer, the nuclear pore complex (NPC) has been studied in great detail using a wide spectrum of methods. Consequently, many aspects of its architecture, general function, and role in the life cycle of a cell are well understood. Over the last decade, fluorescence microscopy methods have enabled the real-time visualization of single molecules interacting with and transiting through the NPC, allowing novel questions to be examined with nanometer precision. While initial single-molecule studies focused primarily on import pathways using permeabilized cells, it has recently proven feasible to investigate the export of mRNAs in living cells. Single-molecule assays can address questions that are difficult or impossible to answer by other means, yet the complexity of nucleocytoplasmic transport requires that interpretation be based on a firm genetic, biochemical, and structural foundation. Moreover, conceptually simple single-molecule experiments remain technically challenging, particularly with regard to signal intensity, signal-to-noise ratio, and the analysis of noise, stochasticity, and precision. We discuss nuclear transport issues recently addressed by single-molecule microscopy, evaluate the limits of existing assays and data, and identify open questions for future studies. We expect that single-molecule fluorescence approaches will continue to be applied to outstanding nucleocytoplasmic transport questions, and that the approaches developed for NPC studies are extendable to additional complex systems and pathways within cells.
    Keywords cell cycle ; exports ; fluorescence ; fluorescence microscopy ; information exchange ; messenger RNA ; nucleocytoplasmic transport ; nucleoporins
    Language English
    Dates of publication 2016-0522
    Size p. 2091-2119.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 80229-3
    ISSN 1089-8638 ; 0022-2836
    ISSN (online) 1089-8638
    ISSN 0022-2836
    DOI 10.1016/j.jmb.2016.02.023
    Database NAL-Catalogue (AGRICOLA)

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