1
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Salter T, Collinson I, Allen WJ. Whole Cell Luminescence-Based Screen for Inhibitors of the Bacterial Sec Machinery. Biochemistry 2024. [PMID: 39207823 DOI: 10.1021/acs.biochem.4c00264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
There is a pressing need for new antibiotics to combat rising resistance to those already in use. The bacterial general secretion (Sec) system has long been considered a good target for novel antimicrobials thanks to its irreplacable role in maintaining cell envelope integrity, yet the lack of a robust, high-throughput method to screen for Sec inhibition has so far hampered efforts to realize this potential. Here, we have adapted our recently developed in vitro assay for Sec activity─based on the split NanoLuc luciferase─to work at scale and in living cells. A simple counterscreen allows compounds that specifically target Sec to be distinguished from those with other effects on cellular function. As proof of principle, we have applied this assay to a library of 5000 compounds and identified a handful of moderately effective in vivo inhibitors of Sec. Although these hits are unlikely to be potent enough to use as a basis for drug development, they demonstrate the efficacy of the screen. We therefore anticipate that the methods presented here will be scalable to larger compound libraries, in the ultimate quest for Sec inhibitors with clinically relevant properties.
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Affiliation(s)
- Tia Salter
- School of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
| | - Ian Collinson
- School of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
| | - William J Allen
- School of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
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2
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Job AM, Doran KS, Spencer BL. A group B streptococcal type VII-secreted LXG toxin mediates interbacterial competition and colonization of the murine female genital tract. mBio 2024:e0208824. [PMID: 39189749 DOI: 10.1128/mbio.02088-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2024] [Accepted: 07/22/2024] [Indexed: 08/28/2024] Open
Abstract
Group B Streptococcus (GBS) asymptomatically colonizes the vagina but can opportunistically ascend to the uterus and be transmitted vertically during pregnancy, resulting in neonatal pneumonia, bacteremia, and meningitis. GBS is a leading etiologic agent of neonatal infection and understanding the mechanisms by which GBS persists within the polymicrobial female genital mucosa has the potential to mitigate subsequent transmission and disease. Type VIIb secretion systems (T7SSb) are encoded by Bacillota and often mediate interbacterial competition using LXG toxins that contain conserved N-termini important for secretion and variable C-terminal toxin domains that confer diverse biochemical activities. Our recent work characterized a role for the GBS T7SSb in vaginal colonization and ascending infection but the mechanisms by which the T7SSb promotes GBS persistence in this polymicrobial niche remain unknown. Herein, we investigate the GBS T7SS in interbacterial competition and GBS niche establishment in the female genital tract. We demonstrate GBS T7SS-dependent inhibition of mucosal pathobiont Enterococcus faecalis both in vitro using predator-prey assays and in vivo in the murine genital tract and found that a GBS LXG protein encoded within the T7SS locus (herein named group B streptococcal LXG Toxin A) contributes to these phenotypes. We identify BltA as a T7SS substrate that is toxic to E. coli and S. aureus upon induction of intracellular expression along with associated chaperones. Finally, we show that BltA and its chaperones contribute to GBS vaginal colonization. Altogether, these data reveal a role for a novel T7b-secreted toxin in GBS mucosal persistence and competition.IMPORTANCECompetition between neighboring, non-kin bacteria is essential for microbial niche establishment in mucosal environments. Gram-positive bacteria encoding T7SSb have been shown to engage in competition through the export of LXG-motif-containing toxins, but these have not been characterized in group B Streptococcus (GBS), an opportunistic colonizer of the polymicrobial female genital tract. Here, we show a role for GBS T7SS in competition with mucosal pathobiont Enterococcus faecalis, both in vitro and in vivo. We further find that a GBS LXG protein contributing to this antagonism is exported by the T7SS and is intracellularly toxic to other bacteria; therefore, we have named this protein group B streptococcal LXG Toxin A (BltA). Finally, we show that BltA and its associated chaperones promote persistence within female genital tract tissues, in vivo. These data reveal previously unrecognized mechanisms by which GBS may compete with other mucosal opportunistic pathogens to persist within the female genital tract.
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Affiliation(s)
- Alyx M Job
- Department of Immunology and Microbiology, University of Colorado Anschutz, Aurora, Colorado, USA
| | - Kelly S Doran
- Department of Immunology and Microbiology, University of Colorado Anschutz, Aurora, Colorado, USA
| | - Brady L Spencer
- Department of Immunology and Microbiology, University of Colorado Anschutz, Aurora, Colorado, USA
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3
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Yang Y, Scott AA, Kneuper H, Alcock F, Palmer T. High-throughput functional analysis provides novel insight into type VII secretion in Staphylococcus aureus. Open Biol 2024; 14:240060. [PMID: 39139050 PMCID: PMC11322744 DOI: 10.1098/rsob.240060] [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: 03/10/2024] [Revised: 06/10/2024] [Accepted: 06/28/2024] [Indexed: 08/15/2024] Open
Abstract
Successful colonization by the opportunistic pathogen Staphylococcus aureus depends on its ability to interact with other microorganisms. Staphylococcus aureus strains harbour a T7b subtype of type VII secretion system (T7SSb), a protein secretion system found in a wide variety of Bacillota, which functions in bacterial antagonism and virulence. Assessment of T7SSb activity in S. aureus has been hampered by low secretion activity under laboratory conditions and the lack of a sensitive assay to measure secretion. Here, we have utilized NanoLuc binary technology to develop a simple assay to monitor protein secretion via detection of bioluminescence. Fusion of the 11 amino acid NanoLuc fragment to the conserved substrate EsxA permits its extracellular detection upon supplementation with the large NanoLuc fragment and luciferase substrate. Following miniaturization of the assay to 384-well format, we use high-throughput analysis to demonstrate that T7SSb-dependent protein secretion differs across strains and growth temperature. We further show that the same assay can be used to monitor secretion of the surface-associated toxin substrate TspA. Using this approach, we identify three conserved accessory proteins required to mediate TspA secretion. Co-purification experiments confirm that all three proteins form a complex with TspA.
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Affiliation(s)
- Yaping Yang
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon TyneNE2 4HH, UK
| | - Aaron A. Scott
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon TyneNE2 4HH, UK
| | - Holger Kneuper
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon TyneNE2 4HH, UK
| | - Felicity Alcock
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon TyneNE2 4HH, UK
| | - Tracy Palmer
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon TyneNE2 4HH, UK
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4
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Job AM, Doran KS, Spencer BL. A group B streptococcal type VII secreted LXG toxin mediates interbacterial competition and colonization of the female genital tract. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.10.598350. [PMID: 38915665 PMCID: PMC11195062 DOI: 10.1101/2024.06.10.598350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Group B Streptococcus (GBS) asymptomatically colonizes the vagina but can opportunistically ascend to the uterus and be transmitted vertically during pregnancy, resulting in neonatal pneumonia, bacteremia and meningitis. GBS is a leading etiologic agent of neonatal infection and understanding the mechanisms by which GBS persists within the polymicrobial female genital mucosa has potential to mitigate subsequent transmission and disease. Type VIIb secretion systems (T7SSb) are encoded by Firmicutes and often mediate interbacterial competition using LXG toxins that contain conserved N-termini important for secretion and variable C-terminal toxin domains that confer diverse biochemical activities. Our recent work characterized a role for the GBS T7SSb in vaginal colonization and ascending infection but the mechanisms by which the T7SSb promotes GBS persistence in this polymicrobial niche remain unknown. Herein, we investigate the GBS T7SS in interbacterial competition and GBS niche establishment in the female genital tract. We demonstrate GBS T7SS-dependent inhibition of mucosal pathobiont Enterococcus faecalis both in vitro using predator-prey assays and in vivo in the murine genital tract and found that a GBS LXG protein encoded within the T7SS locus (herein named group B streptococcal LXG Toxin A) that contributes to these phenotypes. We identify BltA as a T7SS substrate that is toxic to E. coli and S. aureus upon induction of expression along with associated chaperones. Finally, we show that BltA and its chaperones contribute to GBS vaginal colonization. Altogether, these data reveal a role for a novel T7b-secreted toxin in GBS mucosal persistence and competition.
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Affiliation(s)
- Alyx M. Job
- Department of Immunology and Microbiology, University of Colorado Anschutz, Aurora, CO, USA
| | - Kelly S. Doran
- Department of Immunology and Microbiology, University of Colorado Anschutz, Aurora, CO, USA
| | - Brady L. Spencer
- Department of Immunology and Microbiology, University of Colorado Anschutz, Aurora, CO, USA
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5
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Kes MB, Wang B, van Ulsen P, Hamoen LW, Luirink J. Development of a split-luciferase assay to establish optimal protein secretion conditions for protein production by Bacillus subtilis. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001460. [PMID: 38847798 PMCID: PMC11261832 DOI: 10.1099/mic.0.001460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Accepted: 04/26/2024] [Indexed: 07/24/2024]
Abstract
Bacillus subtilis is a Gram-positive bacterium that is frequently used in the bioindustry for the production of various proteins, because of its superior protein secretion capacities. To determine optimal conditions for protein secretion by B. subtilis, a quick and sensitive method for measuring protein secretion is crucial. A fast and universal assay is most useful for detecting diverse proteins in a high-throughput manner. In this study, we introduce a split-luciferase-based method for measuring protein secretion by B. subtilis. The NanoBiT system was used to monitor secretion of four different proteins: xylanase A, amylase M, protein glutaminase A, and GFP nanobody. Our findings underscore the split-luciferase system as a quick, sensitive, and user-friendly method.
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Affiliation(s)
- Mariah B.M.J. Kes
- Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
| | - Biwen Wang
- Bacterial Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Peter van Ulsen
- Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
| | - Leendert W. Hamoen
- Bacterial Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Joen Luirink
- Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
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6
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Needs HI, Glover E, Pereira GC, Witt A, Hübner W, Dodding MP, Henley JM, Collinson I. Rescue of mitochondrial import failure by intercellular organellar transfer. Nat Commun 2024; 15:988. [PMID: 38307874 PMCID: PMC10837123 DOI: 10.1038/s41467-024-45283-2] [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: 02/01/2023] [Accepted: 01/19/2024] [Indexed: 02/04/2024] Open
Abstract
Mitochondria are the powerhouses of eukaryotic cells, composed mostly of nuclear-encoded proteins imported from the cytosol. Thus, problems with the import machinery will disrupt their regenerative capacity and the cell's energy supplies - particularly troublesome for energy-demanding cells of nervous tissue and muscle. Unsurprisingly then, import breakdown is implicated in disease. Here, we explore the consequences of import failure in mammalian cells; wherein, blocking the import machinery impacts mitochondrial ultra-structure and dynamics, but, surprisingly, does not affect import. Our data are consistent with a response involving intercellular mitochondrial transport via tunnelling nanotubes to import healthy mitochondria and jettison those with blocked import sites. These observations support the existence of a widespread mechanism for the rescue of mitochondrial dysfunction.
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Affiliation(s)
- Hope I Needs
- School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK
| | - Emily Glover
- School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK
| | - Gonçalo C Pereira
- School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK
- Nanna Therapeutics, Merrifield Centre, Rosemary Lane, Cambridge, CB1 3LQ, UK
| | - Alina Witt
- Fakultät für Physik, Universität Bielefeld, Bielefeld, Postfach 100131 D-33501, Germany
| | - Wolfgang Hübner
- Fakultät für Physik, Universität Bielefeld, Bielefeld, Postfach 100131 D-33501, Germany
| | - Mark P Dodding
- School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK
| | - Jeremy M Henley
- School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK.
| | - Ian Collinson
- School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK.
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7
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Klein TA, Shah PY, Gkragkopoulou P, Grebenc DW, Kim Y, Whitney JC. Structure of a tripartite protein complex that targets toxins to the type VII secretion system. Proc Natl Acad Sci U S A 2024; 121:e2312455121. [PMID: 38194450 PMCID: PMC10801868 DOI: 10.1073/pnas.2312455121] [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: 07/20/2023] [Accepted: 11/20/2023] [Indexed: 01/11/2024] Open
Abstract
Type VII secretion systems are membrane-embedded nanomachines used by Gram-positive bacteria to export effector proteins from the cytoplasm to the extracellular environment. Many of these effectors are polymorphic toxins comprised of an N-terminal Leu-x-Gly (LXG) domain of unknown function and a C-terminal toxin domain that inhibits the growth of bacterial competitors. In recent work, it was shown that LXG effectors require two cognate Lap proteins for T7SS-dependent export. Here, we present the 2.6 Å structure of the LXG domain of the TelA toxin from the opportunistic pathogen Streptococcus intermedius in complex with both of its cognate Lap targeting factors. The structure reveals an elongated α-helical bundle within which each Lap protein makes extensive hydrophobic contacts with either end of the LXG domain. Remarkably, despite low overall sequence identity, we identify striking structural similarity between our LXG complex and PE-PPE heterodimers exported by the distantly related ESX type VII secretion systems of Mycobacteria implying a conserved mechanism of effector export among diverse Gram-positive bacteria. Overall, our findings demonstrate that LXG domains, in conjunction with their cognate Lap targeting factors, represent a tripartite secretion signal for a widespread family of T7SS toxins.
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Affiliation(s)
- Timothy A. Klein
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ONL8S 4K1, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ONL8S 4K1, Canada
| | - Prakhar Y. Shah
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ONL8S 4K1, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ONL8S 4K1, Canada
| | - Polyniki Gkragkopoulou
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ONL8S 4K1, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ONL8S 4K1, Canada
| | - Dirk W. Grebenc
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ONL8S 4K1, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ONL8S 4K1, Canada
| | - Youngchang Kim
- Structural Biology Center, X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, IL60439
| | - John C. Whitney
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ONL8S 4K1, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ONL8S 4K1, Canada
- David Braley Centre for Antibiotic Discovery, McMaster University, Hamilton, ONL8S 4K1, Canada
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8
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Crossley JA, Allen WJ, Watkins DW, Sabir T, Radford SE, Tuma R, Collinson I, Fessl T. Dynamic coupling of fast channel gating with slow ATP-turnover underpins protein transport through the Sec translocon. EMBO J 2024; 43:1-13. [PMID: 38177311 PMCID: PMC10883268 DOI: 10.1038/s44318-023-00004-1] [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: 06/30/2023] [Revised: 11/06/2023] [Accepted: 11/08/2023] [Indexed: 01/06/2024] Open
Abstract
The Sec translocon is a highly conserved membrane assembly for polypeptide transport across, or into, lipid bilayers. In bacteria, secretion through the core channel complex-SecYEG in the inner membrane-is powered by the cytosolic ATPase SecA. Here, we use single-molecule fluorescence to interrogate the conformational state of SecYEG throughout the ATP hydrolysis cycle of SecA. We show that the SecYEG channel fluctuations between open and closed states are much faster (~20-fold during translocation) than ATP turnover, and that the nucleotide status of SecA modulates the rates of opening and closure. The SecY variant PrlA4, which exhibits faster transport but unaffected ATPase rates, increases the dwell time in the open state, facilitating pre-protein diffusion through the pore and thereby enhancing translocation efficiency. Thus, rapid SecYEG channel dynamics are allosterically coupled to SecA via modulation of the energy landscape, and play an integral part in protein transport. Loose coupling of ATP-turnover by SecA to the dynamic properties of SecYEG is compatible with a Brownian-rachet mechanism of translocation, rather than strict nucleotide-dependent interconversion between different static states of a power stroke.
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Affiliation(s)
- Joel A Crossley
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
- Faculty of Science, University of South Bohemia, České Budějovice, 370 05, Czech Republic
- School of Clinical and Applied Sciences, Leeds Beckett University, Leeds, LS1 3HE, UK
| | - William J Allen
- School of Biochemistry, University of Bristol, Bristol, BS8 1QU, UK
| | - Daniel W Watkins
- School of Biochemistry, University of Bristol, Bristol, BS8 1QU, UK
| | - Tara Sabir
- School of Clinical and Applied Sciences, Leeds Beckett University, Leeds, LS1 3HE, UK
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Roman Tuma
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
- Faculty of Science, University of South Bohemia, České Budějovice, 370 05, Czech Republic
| | - Ian Collinson
- School of Biochemistry, University of Bristol, Bristol, BS8 1QU, UK.
| | - Tomas Fessl
- Faculty of Science, University of South Bohemia, České Budějovice, 370 05, Czech Republic.
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9
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Garrett SR, Mietrach N, Deme J, Bitzer A, Yang Y, Ulhuq FR, Kretschmer D, Heilbronner S, Smith TK, Lea SM, Palmer T. A type VII-secreted lipase toxin with reverse domain arrangement. Nat Commun 2023; 14:8438. [PMID: 38114483 PMCID: PMC10730906 DOI: 10.1038/s41467-023-44221-y] [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: 08/03/2023] [Accepted: 12/05/2023] [Indexed: 12/21/2023] Open
Abstract
The type VII protein secretion system (T7SS) is found in many Gram-positive bacteria and in pathogenic mycobacteria. All T7SS substrate proteins described to date share a common helical domain architecture at the N-terminus that typically interacts with other helical partner proteins, forming a composite signal sequence for targeting to the T7SS. The C-terminal domains are functionally diverse and in Gram-positive bacteria such as Staphylococcus aureus often specify toxic anti-bacterial activity. Here we describe the first example of a class of T7 substrate, TslA, that has a reverse domain organisation. TslA is widely found across Bacillota including Staphylococcus, Enterococcus and Listeria. We show that the S. aureus TslA N-terminal domain is a phospholipase A with anti-staphylococcal activity that is neutralised by the immunity lipoprotein TilA. Two small helical partner proteins, TlaA1 and TlaA2 are essential for T7-dependent secretion of TslA and at least one of these interacts with the TslA C-terminal domain to form a helical stack. Cryo-EM analysis of purified TslA complexes indicate that they share structural similarity with canonical T7 substrates. Our findings suggest that the T7SS has the capacity to recognise a secretion signal present at either end of a substrate.
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Affiliation(s)
- Stephen R Garrett
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Nicole Mietrach
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Justin Deme
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, NIH, Frederick, MD, 21702, USA
| | - Alina Bitzer
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, 72076, Tübingen, Germany
| | - Yaping Yang
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Fatima R Ulhuq
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Dorothee Kretschmer
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, 72076, Tübingen, Germany
| | - Simon Heilbronner
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, 72076, Tübingen, Germany
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | - Terry K Smith
- School of Biology, Biomedical Sciences Research Complex, University of St. Andrews, North Haugh, St. Andrews, United Kingdom
| | - Susan M Lea
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, NIH, Frederick, MD, 21702, USA
| | - Tracy Palmer
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
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10
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Zhou W, Hao B, Bricker TM, Theg SM. A real-time analysis of protein transport via the twin arginine translocation pathway in response to different components of the protonmotive force. J Biol Chem 2023; 299:105286. [PMID: 37742925 PMCID: PMC10641609 DOI: 10.1016/j.jbc.2023.105286] [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: 07/17/2023] [Revised: 08/28/2023] [Accepted: 09/18/2023] [Indexed: 09/26/2023] Open
Abstract
The twin arginine translocation (Tat) pathway transports folded protein across the cytoplasmic membrane in bacteria, archaea, and across the thylakoid membrane in plants as well as the inner membrane in some mitochondria. In plant chloroplasts, the Tat pathway utilizes the protonmotive force (PMF) to drive protein translocation. However, in bacteria, it has been shown that Tat transport depends only on the transmembrane electrical potential (Δψ) component of PMF in vitro. To investigate the comprehensive PMF requirement in Escherichia coli, we have developed the first real-time assay to monitor Tat transport utilizing the NanoLuc Binary Technology in E. coli spheroplasts. This luminescence assay allows for continuous monitoring of Tat transport with high-resolution, making it possible to observe subtle changes in transport in response to different treatments. By applying the NanoLuc assay, we report that, under acidic conditions (pH = 6.3), ΔpH, in addition to Δψ, contributes energetically to Tat transport in vivo in E. coli spheroplasts. These results provide novel insight into the mechanism of energy utilization by the Tat pathway.
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Affiliation(s)
- Wenjie Zhou
- Department of Plant Biology, University of California, Davis, California, USA
| | - Binhan Hao
- Department of Plant Biology, University of California, Davis, California, USA
| | - Terry M Bricker
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Steven M Theg
- Department of Plant Biology, University of California, Davis, California, USA.
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11
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Choi IY, Oh JH, Wang Z, van Pijkeren JP. Bioluminescent monitoring of recombinant lactic acid bacteria and their products. mBio 2023; 14:e0119723. [PMID: 37668408 PMCID: PMC10653940 DOI: 10.1128/mbio.01197-23] [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: 05/09/2023] [Accepted: 06/29/2023] [Indexed: 09/06/2023] Open
Abstract
IMPORTANCE Lactic acid bacteria constitute a genetically diverse group of microorganisms with significant roles in the food industry, biotechnology, agriculture, and medicine. A core understanding of bacterial physiology in diverse environments is crucial to select and develop bacteria for industrial and medical applications. However, there is a lack of versatile tools to track (recombinant) protein production in lactic acid bacteria. In this study, we adapted a peptide-based bioluminescent tagging system that is functional across multiple genera and species. This system enables tracking of tagged proteins both in vitro and in situ, while it also can be used to enumerate recombinant bacteria from the mouse gastrointestinal tract with accuracy comparable to that of conventional plate counts. Our work expands the lactic acid bacteria genetic toolbox and will facilitate researchers in industry and academia with opportunities to monitor microbes and proteins under different physiologically relevant conditions.
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Affiliation(s)
- In Young Choi
- Department of Food Science, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Jee-Hwan Oh
- Department of Food Science, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Zhiying Wang
- Department of Food Science, University of Wisconsin-Madison, Madison, Wisconsin, USA
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12
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Allen WJ, Collinson I. A unifying mechanism for protein transport through the core bacterial Sec machinery. Open Biol 2023; 13:230166. [PMID: 37643640 PMCID: PMC10465204 DOI: 10.1098/rsob.230166] [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: 05/31/2023] [Accepted: 07/21/2023] [Indexed: 08/31/2023] Open
Abstract
Encapsulation and compartmentalization are fundamental to the evolution of cellular life, but they also pose a challenge: how to partition the molecules that perform biological functions-the proteins-across impermeable barriers into sub-cellular organelles, and to the outside. The solution lies in the evolution of specialized machines, translocons, found in every biological membrane, which act both as gate and gatekeeper across and into membrane bilayers. Understanding how these translocons operate at the molecular level has been a long-standing ambition of cell biology, and one that is approaching its denouement; particularly in the case of the ubiquitous Sec system. In this review, we highlight the fruits of recent game-changing technical innovations in structural biology, biophysics and biochemistry to present a largely complete mechanism for the bacterial version of the core Sec machinery. We discuss the merits of our model over alternative proposals and identify the remaining open questions. The template laid out by the study of the Sec system will be of immense value for probing the many other translocons found in diverse biological membranes, towards the ultimate goal of altering or impeding their functions for pharmaceutical or biotechnological purposes.
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Affiliation(s)
- William J. Allen
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Ian Collinson
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
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13
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Needs HI, Lorriman JS, Pereira GC, Henley JM, Collinson I. The MitoLuc Assay System for Accurate Real-Time Monitoring of Mitochondrial Protein Import Within Mammalian Cells. J Mol Biol 2023; 435:168129. [PMID: 37105499 PMCID: PMC7616392 DOI: 10.1016/j.jmb.2023.168129] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 03/31/2023] [Accepted: 04/19/2023] [Indexed: 04/29/2023]
Abstract
Mitochondrial protein import is critical for organelle biogenesis, bioenergetic function, and health. The mechanism of which is poorly understood, particularly of the mammalian system. To address this problem we have established an assay to quantitatively monitor mitochondrial import inside mammalian cells. The reporter is based on a split luciferase, whereby the large fragment is segregated in the mitochondrial matrix and the small complementary fragment is fused to the C-terminus of a purified recombinant precursor protein destined for import. Following import the complementary fragments combine to form an active luciferase-providing a sensitive, accurate and continuous measure of protein import. This advance allows detailed mechanistic examination of the transport process in live cells, including the analysis of import breakdown associated with disease, and high-throughput drug screening. Furthermore, the set-up has the potential to be adapted for the analysis of alternative protein transport systems within different cell types, and multicellular model organisms.
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Affiliation(s)
- Hope I Needs
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK. https://twitter.com/hopeneeds
| | - James S Lorriman
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK. https://twitter.com/JamesLorriman
| | - Gonçalo C Pereira
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK. https://twitter.com/MitoPereira_GC
| | - Jeremy M Henley
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Ian Collinson
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK.
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14
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Needs HI, Wilkinson KA, Henley JM, Collinson I. Aggregation-prone Tau impairs mitochondrial import, which affects organelle morphology and neuronal complexity. J Cell Sci 2023; 136:jcs260993. [PMID: 37303235 PMCID: PMC10357015 DOI: 10.1242/jcs.260993] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 06/05/2023] [Indexed: 06/13/2023] Open
Abstract
Mitochondrial protein import is essential for organellar biogenesis, and thereby for the sufficient supply of cytosolic ATP - which is particularly important for cells with high energy demands like neurons. This study explores the prospect of import machinery perturbation as a cause of neurodegeneration instigated by the accumulation of aggregating proteins linked to disease. We found that the aggregation-prone Tau variant (TauP301L) reduces the levels of components of the import machinery of the outer (TOM20, encoded by TOMM20) and inner membrane (TIM23, encoded by TIMM23) while associating with TOM40 (TOMM40). Intriguingly, this interaction affects mitochondrial morphology, but not protein import or respiratory function; raising the prospect of an intrinsic rescue mechanism. Indeed, TauP301L induced the formation of tunnelling nanotubes (TNTs), potentially for the recruitment of healthy mitochondria from neighbouring cells and/or the disposal of mitochondria incapacitated by aggregated Tau. Consistent with this, inhibition of TNT formation (and rescue) reveals Tau-induced import impairment. In primary neuronal cultures, TauP301L induced morphological changes characteristic of neurodegeneration. Interestingly, these effects were mirrored in cells where the import sites were blocked artificially. Our results reveal a link between aggregation-prone Tau and defective mitochondrial import relevant to disease.
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Affiliation(s)
- Hope I. Needs
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | | | - Jeremy M. Henley
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Ian Collinson
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
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15
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Jain N, Gomkale R, Bernhard O, Rehling P, Cruz-Zaragoza LD. A quantitative fluorescence-based approach to study mitochondrial protein import. EMBO Rep 2023; 24:e55760. [PMID: 36938994 PMCID: PMC10157374 DOI: 10.15252/embr.202255760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 01/22/2023] [Accepted: 02/17/2023] [Indexed: 03/21/2023] Open
Abstract
Mitochondria play central roles in cellular energy production and metabolism. Most proteins required to carry out these functions are synthesized in the cytosol and imported into mitochondria. A growing number of metabolic disorders arising from mitochondrial dysfunction can be traced to errors in mitochondrial protein import. The mechanisms underlying the import of precursor proteins are commonly studied using radioactively labeled precursor proteins imported into purified mitochondria. Here, we establish a fluorescence-based import assay to analyze protein import into mitochondria. We show that fluorescently labeled precursors enable import analysis with similar sensitivity to those using radioactive precursors, yet they provide the advantage of quantifying import with picomole resolution. We adapted the import assay to a 96-well plate format allowing for fast analysis in a screening-compatible format. Moreover, we show that fluorescently labeled precursors can be used to monitor the assembly of the F1 F0 ATP synthase in purified mitochondria. Thus, we provide a sensitive fluorescence-based import assay that enables quantitative and fast import analysis.
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Affiliation(s)
- Naintara Jain
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Ridhima Gomkale
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Olaf Bernhard
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Peter Rehling
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany.,Max Planck Institute for Multidisciplinary Science, Göttingen, Germany
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16
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Gräwe A, Merkx M. Bioluminescence Goes Dark: Boosting the Performance of Bioluminescent Sensor Proteins Using Complementation Inhibitors. ACS Sens 2022; 7:3800-3808. [PMID: 36450135 PMCID: PMC9791688 DOI: 10.1021/acssensors.2c01726] [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] [Indexed: 12/02/2022]
Abstract
Bioluminescent sensor proteins have recently gained popularity in both basic research and point-of-care diagnostics. Sensor proteins based on intramolecular complementation of split NanoLuc are particularly attractive because their intrinsic modular design enables for systematic tuning of sensor properties. Here we show how the sensitivity of these sensors can be enhanced by the introduction of catalytically inactive variants of the small SmBiT subunit (DarkBiTs) as intramolecular inhibitors. Starting from previously developed bioluminescent antibody sensor proteins (LUMABS), we developed single component, biomolecular switches with a strongly reduced background signal for the detection of three clinically relevant antibodies, anti-HIV1-p17, cetuximab (CTX), and an RSV neutralizing antibody (101F). These new dark-LUMABS sensors showed 5-13-fold increases in sensitivity which translated into lower limits of detection. The use of DarkBiTs as competitive intramolecular inhibitor domains is not limited to the LUMABS sensor family and might be used to boost the performance of other bioluminescent sensor proteins based on split luciferase complementation.
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17
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McArthur N, Cruz-Teran C, Thatavarty A, Reeves GT, Rao BM. Experimental and Analytical Framework for "Mix-and-Read" Assays Based on Split Luciferase. ACS OMEGA 2022; 7:24551-24560. [PMID: 35874239 PMCID: PMC9301641 DOI: 10.1021/acsomega.2c02319] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The use of immunodetection assays including the widely used enzyme-linked immunosorbent assay (ELISA) in applications such as point-of-care detection is often limited by the need for protein immobilization and multiple binding and washing steps. Here, we describe an experimental and analytical framework for the development of simple and modular "mix-and-read" enzymatic complementation assays based on split luciferase that enable sensitive detection and quantification of analytes in solution. In this assay, two engineered protein binders targeting nonoverlapping epitopes on the target analyte were each fused to nonactive fragments of luciferase to create biosensor probes. Binding proteins to two model targets, lysozyme and Sso6904, were isolated from a combinatorial library of Sso7d mutants using yeast surface display. In the presence of the analyte, probes were brought into close proximity, reconstituting enzymatic activity of luciferase and enabling detection of low picomolar concentrations of the analyte by chemiluminescence. Subsequently, we constructed an equilibrium binding model that relates binding affinities of the binding proteins for the target, assay parameters such as the concentrations of probes used, and assay performance (limit of detection and concentration range over which the target can be quantified). Overall, our experimental and analytical framework provides the foundation for the development of split luciferase assays for detection and quantification of various targets.
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Affiliation(s)
- Nikki McArthur
- Department
of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Carlos Cruz-Teran
- Department
of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Apoorva Thatavarty
- Department
of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Gregory T. Reeves
- Department
of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States
- Interdisciplinary
Program in Genetics, Texas A&M University, College Station, Texas 77843, United States
| | - Balaji M. Rao
- Department
of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
- Golden
LEAF Biomanufacturing Training and Education Center (BTEC), North Carolina State University, Raleigh, North Carolina 27695, United States
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18
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Fromm K, Boegli A, Ortelli M, Wagner A, Bohn E, Malmsheimer S, Wagner S, Dehio C. Bartonella taylorii: A Model Organism for Studying Bartonella Infection in vitro and in vivo. Front Microbiol 2022; 13:913434. [PMID: 35910598 PMCID: PMC9336547 DOI: 10.3389/fmicb.2022.913434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 05/05/2022] [Indexed: 11/13/2022] Open
Abstract
Bartonella spp. are Gram-negative facultative intracellular pathogens that infect diverse mammals and cause a long-lasting intra-erythrocytic bacteremia in their natural host. These bacteria translocate Bartonella effector proteins (Beps) into host cells via their VirB/VirD4 type 4 secretion system (T4SS) in order to subvert host cellular functions, thereby leading to the downregulation of innate immune responses. Most studies on the functional analysis of the VirB/VirD4 T4SS and the Beps were performed with the major zoonotic pathogen Bartonella henselae for which efficient in vitro infection protocols have been established. However, its natural host, the cat, is unsuitable as an experimental infection model. In vivo studies were mostly confined to rodent models using rodent-specific Bartonella species, while the in vitro infection protocols devised for B. henselae are not transferable for those pathogens. The disparities of in vitro and in vivo studies in different species have hampered progress in our understanding of Bartonella pathogenesis. Here we describe the murine-specific strain Bartonella taylorii IBS296 as a new model organism facilitating the study of bacterial pathogenesis both in vitro in cell cultures and in vivo in laboratory mice. We implemented the split NanoLuc luciferase-based translocation assay to study BepD translocation through the VirB/VirD4 T4SS. We found increased effector-translocation into host cells if the bacteria were grown on tryptic soy agar (TSA) plates and experienced a temperature shift immediately before infection. The improved infectivity in vitro was correlating to an upregulation of the VirB/VirD4 T4SS. Using our adapted infection protocols, we showed BepD-dependent immunomodulatory phenotypes in vitro. In mice, the implemented growth conditions enabled infection by a massively reduced inoculum without having an impact on the course of the intra-erythrocytic bacteremia. The established model opens new avenues to study the role of the VirB/VirD4 T4SS and the translocated Bep effectors in vitro and in vivo.
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Affiliation(s)
- Katja Fromm
- Biozentrum, University of Basel, Basel, Switzerland
| | - Alexandra Boegli
- Department of Biochemistry, Faculty of Biology and Medicine, Université de Lausanne, Epalinges, Switzerland
| | | | | | - Erwin Bohn
- Institute of Medical Microbiology and Hygiene, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), University of Tübingen, Tübingen, Germany
| | - Silke Malmsheimer
- Section of Cellular and Molecular Microbiology, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), University of Tübingen, Tübingen, Germany
| | - Samuel Wagner
- Section of Cellular and Molecular Microbiology, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), University of Tübingen, Tübingen, Germany
- Excellence Cluster “Controlling Microbes to Fight Infections” (CMFI), Tübingen, Germany
- Partner-site Tübingen, German Center for Infection Research (DZIF), Tübingen, Germany
| | - Christoph Dehio
- Biozentrum, University of Basel, Basel, Switzerland
- *Correspondence: Christoph Dehio,
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19
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Ford HC, Allen WJ, Pereira GC, Liu X, Dillingham MS, Collinson I. Towards a molecular mechanism underlying mitochondrial protein import through the TOM and TIM23 complexes. eLife 2022; 11:75426. [PMID: 35674314 PMCID: PMC9255969 DOI: 10.7554/elife.75426] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 06/07/2022] [Indexed: 12/27/2022] Open
Abstract
Nearly all mitochondrial proteins need to be targeted for import from the cytosol. For the majority, the first port of call is the translocase of the outer membrane (TOM complex), followed by a procession of alternative molecular machines, conducting transport to their final destination. The pre-sequence translocase of the inner membrane (TIM23-complex) imports proteins with cleavable pre-sequences. Progress in understanding these transport mechanisms has been hampered by the poor sensitivity and time resolution of import assays. However, with the development of an assay based on split NanoLuc luciferase, we can now explore this process in greater detail. Here, we apply this new methodology to understand how ∆ψ and ATP hydrolysis, the two main driving forces for import into the matrix, contribute to the transport of pre-sequence-containing precursors (PCPs) with varying properties. Notably, we found that two major rate-limiting steps define PCP import time: passage of PCP across the outer membrane and initiation of inner membrane transport by the pre-sequence - the rates of which are influenced by PCP size and net charge. The apparent distinction between transport through the two membranes (passage through TOM is substantially complete before PCP-TIM engagement) is in contrast with the current view that import occurs through TOM and TIM in a single continuous step. Our results also indicate that PCPs spend very little time in the TIM23 channel - presumably rapid success or failure of import is critical for maintenance of mitochondrial fitness.
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Affiliation(s)
- Holly C Ford
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - William J Allen
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Gonçalo C Pereira
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Xia Liu
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | | | - Ian Collinson
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
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20
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Allen WJ, Corey RA, Watkins DW, Oliveira ASF, Hards K, Cook GM, Collinson I. Rate-limiting transport of positively charged arginine residues through the Sec-machinery is integral to the mechanism of protein secretion. eLife 2022; 11:e77586. [PMID: 35486093 PMCID: PMC9110029 DOI: 10.7554/elife.77586] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 04/29/2022] [Indexed: 11/24/2022] Open
Abstract
Transport of proteins across and into membranes is a fundamental biological process with the vast majority being conducted by the ubiquitous Sec machinery. In bacteria, this is usually achieved when the SecY-complex engages the cytosolic ATPase SecA (secretion) or translating ribosomes (insertion). Great strides have been made towards understanding the mechanism of protein translocation. Yet, important questions remain - notably, the nature of the individual steps that constitute transport, and how the proton-motive force (PMF) across the plasma membrane contributes. Here, we apply a recently developed high-resolution protein transport assay to explore these questions. We find that pre-protein transport is limited primarily by the diffusion of arginine residues across the membrane, particularly in the context of bulky hydrophobic sequences. This specific effect of arginine, caused by its positive charge, is mitigated for lysine which can be deprotonated and transported across the membrane in its neutral form. These observations have interesting implications for the mechanism of protein secretion, suggesting a simple mechanism through which the PMF can aid transport by enabling a 'proton ratchet', wherein re-protonation of exiting lysine residues prevents channel re-entry, biasing transport in the outward direction.
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Affiliation(s)
- William J Allen
- School of Biochemistry, University of Bristol, University WalkBristolUnited Kingdom
| | - Robin A Corey
- School of Biochemistry, University of Bristol, University WalkBristolUnited Kingdom
| | - Daniel W Watkins
- School of Biochemistry, University of Bristol, University WalkBristolUnited Kingdom
| | - A Sofia F Oliveira
- School of Biochemistry, University of Bristol, University WalkBristolUnited Kingdom
- School of Chemistry, University of Bristol, University WalkBristolUnited Kingdom
| | - Kiel Hards
- Department of Microbiology and Immunology, University of OtagoDunedinNew Zealand
| | - Gregory M Cook
- Department of Microbiology and Immunology, University of OtagoDunedinNew Zealand
| | - Ian Collinson
- School of Biochemistry, University of Bristol, University WalkBristolUnited Kingdom
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21
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Recent Advancements in Tracking Bacterial Effector Protein Translocation. Microorganisms 2022; 10:microorganisms10020260. [PMID: 35208715 PMCID: PMC8876096 DOI: 10.3390/microorganisms10020260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/19/2022] [Accepted: 01/20/2022] [Indexed: 11/17/2022] Open
Abstract
Bacteria-host interactions are characterized by the delivery of bacterial virulence factors, i.e., effectors, into host cells where they counteract host immunity and exploit host responses allowing bacterial survival and spreading. These effectors are translocated into host cells by means of dedicated secretion systems such as the type 3 secretion system (T3SS). A comprehensive understanding of effector translocation in a spatio-temporal manner is of critical importance to gain insights into an effector’s mode of action. Various approaches have been developed to understand timing and order of effector translocation, quantities of translocated effectors and their subcellular localization upon translocation into host cells. Recently, the existing toolset has been expanded by newly developed state-of-the art methods to monitor bacterial effector translocation and dynamics. In this review, we elaborate on reported methods and discuss recent advances and shortcomings in this area of tracking bacterial effector translocation.
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22
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Salim H, Pei D. Assessing the Cellular Uptake, Endosomal Escape, and Cytosolic Entry Efficiencies of Cyclic Peptides. Methods Mol Biol 2022; 2371:301-316. [PMID: 34596855 DOI: 10.1007/978-1-0716-1689-5_16] [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] [Indexed: 06/13/2023]
Abstract
Intracellular biologics such as cyclic peptides are an emerging class of macromolecular drugs that are either intrinsically cell permeable or can be effectively delivered into the cell interior to modulate the activity of previously intractable drug targets. They generally enter the mammalian cell by endocytosis mechanisms and are initially localized inside the endosomes. They subsequently escape from the endosomes (and/or lysosomes) into the cytosol with varying efficiencies. In this chapter, we provide the detailed protocol for a flow cytometry-based assay method to quantitate the overall cellular uptake, endosomal escape, and cytosolic entry efficiencies of biomolecules (e.g., linear and cyclic peptides, proteins, and nucleic acids), by using cell-penetrating peptides as an example. The scope of applicability, strengths, and weaknesses of this assay are also discussed.
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Affiliation(s)
- Heba Salim
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
| | - Dehua Pei
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA.
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23
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Alavi MV. OMA1 High-Throughput Screen Reveals Protease Activation by Kinase Inhibitors. ACS Chem Biol 2021; 16:2202-2211. [PMID: 34672515 DOI: 10.1021/acschembio.1c00350] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Mitochondrial proteases are interesting but challenging drug targets for multifactorial diseases, such as neurodegeneration and cancer. The mitochondrial inner membrane protease OMA1 is a bona fide drug target for heart failure supported by data from human linkage analysis and animal disease models, but presumably relevant for more indications. OMA1 acts at the intersection of energy metabolism and stress signaling. The protease cleaves the structural protein OPA1, which organizes the cristae, as well as the signaling peptide DELE1, which can stimulate the integrated stress response. OMA1 shows little activity under physiological conditions but hydrolyzes OPA1 in mitochondria destined for mitophagy and during apoptosis. Little is known about OMA1, its structure has not been solved, let alone its context-dependent regulation. Autocatalytic processing and the lack of OMA1 inhibitors are thereby creating the biggest roadblocks. This study introduces a scalable, cellular OMA1 protease assay suitable for high-throughput drug screening. The assay utilizes an engineered luciferase targeted to the inner membrane as artificial OMA1 substrate, whereby the reporter signal inversely correlates to OMA1 activity. Testing different screening protocols and sampling different compound collections validated the reporter and demonstrated that both OMA1 activators as well as OMA1 inhibitors can be identified with the assay. Ten kinase-targeted cancer drugs triggered OMA1 in the assays, which suggests─considering cardiotoxicity as a rather common side-effect of this class of drugs─cross-reactivity with the OMA1 pathway.
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Affiliation(s)
- Marcel V. Alavi
- 712 North Inc., QB3 Incubator at UC Berkeley, 130 Stanley Hall, #3220, Berkeley, California 94720, United States
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24
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Lyu Z, Genereux JC. Methodologies for Measuring Protein Trafficking across Cellular Membranes. Chempluschem 2021; 86:1397-1415. [PMID: 34636167 DOI: 10.1002/cplu.202100304] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/19/2021] [Indexed: 12/11/2022]
Abstract
Nearly all proteins are synthesized in the cytosol. The majority of this proteome must be trafficked elsewhere, such as to membranes, to subcellular compartments, or outside of the cell. Proper trafficking of nascent protein is necessary for protein folding, maturation, quality control and cellular and organismal health. To better understand cellular biology, molecular and chemical technologies to properly characterize protein trafficking (and mistrafficking) have been developed and applied. Herein, we take a biochemical perspective to review technologies that enable spatial and temporal measurement of protein distribution, focusing on both the most widely adopted methodologies and exciting emerging approaches.
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Affiliation(s)
- Ziqi Lyu
- Department of Chemistry, University of California, Riverside, 501 Big Springs Road, 92521, Riverside, CA, USA
| | - Joseph C Genereux
- Department of Chemistry, University of California, Riverside, 501 Big Springs Road, 92521, Riverside, CA, USA
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25
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Gupta R, Toptygin D, Kaiser CM. Synchronized Real-time Measurement of Sec-mediated Protein Translocation. Bio Protoc 2021; 11:e4129. [PMID: 34541047 DOI: 10.21769/bioprotoc.4129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 05/09/2021] [Accepted: 05/27/2021] [Indexed: 11/02/2022] Open
Abstract
The Sec translocon, consisting of a heterotrimeric transmembrane channel (SecYEG) and an associated ATPase (SecA), catalyzes the export of unfolded proteins from the cytosol in bacteria. Kinetically resolving protein translocation at high resolution yields mechanistic insight into the process. Translocation is typically followed by measuring the protection of proteins transported into lipid vesicles, which only allows visualization of translocation after it has already been completed and limits time resolution. Here, we describe the implementation of an assay for measuring translocation in real-time. By priming the reconstituted translocon with suitably engineered substrate proteins, the kinetics of the actual translocation process can be resolved at high resolution. To analyze translocation kinetics, we developed a detailed kinetic model of the process that includes on-pathway and off-pathway processes. Together, this experimental protocol and model permit detailed mechanistic analyses of Sec-dependent protein translocation. Graphic abstract: Synchronized real-time measurements, combined with a detailed kinetic model, enable a mechanistic analysis of protein transport.
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Affiliation(s)
- Riti Gupta
- CMDB Graduate Program, Johns Hopkins University, 3400 N Charles St., Baltimore, MD 21218, USA
| | - Dmitri Toptygin
- Department of Biology, Johns Hopkins University, 3400 N Charles St., Baltimore, MD 21218, USA
| | - Christian M Kaiser
- Department of Biology, Johns Hopkins University, 3400 N Charles St., Baltimore, MD 21218, USA.,Department of Biophysics, Johns Hopkins University, 3400 N Charles St., Baltimore, MD 21218, USA
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26
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Cover TL. Tracking bacterial effector protein delivery into host cells. Mol Microbiol 2021; 116:724-728. [PMID: 34250669 DOI: 10.1111/mmi.14784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 07/08/2021] [Indexed: 11/29/2022]
Abstract
Bacterial Type IV secretion systems (T4SSs) are a functionally heterogeneous group of nanomachines that can deliver substrates into a wide range of target cells. The Helicobacter pylori Cag T4SS has an important role in the pathogenesis of gastric cancer. CagA, the only effector protein known to be secreted by the H. pylori Cag T4SS, enters human gastric cells and causes alterations in intracellular signaling that are linked to cancer pathogenesis. Understanding the molecular mechanisms by which CagA is delivered into gastric cells has been hindered by the lack of robust methods for monitoring this process. A publication in this issue of Molecular Microbiology describes a split luciferase assay for monitoring T4SS-mediated translocation of CagA into host cells. The use of this translocation reporter allowed the quantification of CagA translocation in real-time assays, thereby facilitating the analysis of the kinetics of CagA delivery. This system also allowed the tracking of several types of CagA fusion proteins and confirmed that protein unfolding is important for secretion by the Cag T4SS. This commentary discusses T4SS-dependent delivery of H. pylori CagA into host cells and the use of the split luciferase system for monitoring bacterial protein secretion and delivery into target cells.
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Affiliation(s)
- Timothy L Cover
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.,Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.,Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA
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27
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Lettl C, Haas R, Fischer W. Kinetics of CagA type IV secretion by Helicobacter pylori and the requirement for substrate unfolding. Mol Microbiol 2021; 116:794-807. [PMID: 34121254 DOI: 10.1111/mmi.14772] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 06/02/2021] [Accepted: 06/12/2021] [Indexed: 12/27/2022]
Abstract
Type IV secretion of effector proteins is an important principle for interaction of human pathogens with their target cells. The corresponding secretion systems may transport a multitude of effector proteins that have to be deployed in the respective spatiotemporal context, or only a single translocated protein, as in the case of the CagA effector protein produced by the human gastric pathogen Helicobacter pylori. For a more detailed analysis of the kinetics and mode of action of CagA type IV secretion by H. pylori, we describe here, a novel, highly sensitive split luciferase-based translocation reporter which can be easily adapted to different end-point or real-time measurements. Using this reporter, we showed that H. pylori cells are able to rapidly inject a limited amount of their CagA supply into cultured gastric epithelial cells. We have further employed the reporter system to address the question whether CagA has to be unfolded prior to translocation by the type IV secretion system. We showed that protein domains co-translocated with CagA as protein fusions are more readily tolerated as substrates than in other secretion systems, but also provide evidence that unfolding of effector proteins is a prerequisite for their transport.
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Affiliation(s)
- Clara Lettl
- Max von Pettenkofer Institute of Hygiene and Medical Microbiology, Medical Faculty, LMU Munich, Munich, Germany.,Partner Site Munich, German Center for Infection Research (DZIF), Munich, Germany
| | - Rainer Haas
- Max von Pettenkofer Institute of Hygiene and Medical Microbiology, Medical Faculty, LMU Munich, Munich, Germany.,Partner Site Munich, German Center for Infection Research (DZIF), Munich, Germany
| | - Wolfgang Fischer
- Max von Pettenkofer Institute of Hygiene and Medical Microbiology, Medical Faculty, LMU Munich, Munich, Germany.,Partner Site Munich, German Center for Infection Research (DZIF), Munich, Germany
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28
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Needs HI, Protasoni M, Henley JM, Prudent J, Collinson I, Pereira GC. Interplay between Mitochondrial Protein Import and Respiratory Complexes Assembly in Neuronal Health and Degeneration. Life (Basel) 2021; 11:432. [PMID: 34064758 PMCID: PMC8151517 DOI: 10.3390/life11050432] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/27/2021] [Accepted: 05/02/2021] [Indexed: 12/14/2022] Open
Abstract
The fact that >99% of mitochondrial proteins are encoded by the nuclear genome and synthesised in the cytosol renders the process of mitochondrial protein import fundamental for normal organelle physiology. In addition to this, the nuclear genome comprises most of the proteins required for respiratory complex assembly and function. This means that without fully functional protein import, mitochondrial respiration will be defective, and the major cellular ATP source depleted. When mitochondrial protein import is impaired, a number of stress response pathways are activated in order to overcome the dysfunction and restore mitochondrial and cellular proteostasis. However, prolonged impaired mitochondrial protein import and subsequent defective respiratory chain function contributes to a number of diseases including primary mitochondrial diseases and neurodegeneration. This review focuses on how the processes of mitochondrial protein translocation and respiratory complex assembly and function are interlinked, how they are regulated, and their importance in health and disease.
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Affiliation(s)
- Hope I. Needs
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK; (H.I.N.); (J.M.H.)
| | - Margherita Protasoni
- Medical Research Council-Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; (M.P.); (J.P.)
| | - Jeremy M. Henley
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK; (H.I.N.); (J.M.H.)
- Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Julien Prudent
- Medical Research Council-Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; (M.P.); (J.P.)
| | - Ian Collinson
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK; (H.I.N.); (J.M.H.)
| | - Gonçalo C. Pereira
- Medical Research Council-Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; (M.P.); (J.P.)
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29
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Refined measurement of SecA-driven protein secretion reveals that translocation is indirectly coupled to ATP turnover. Proc Natl Acad Sci U S A 2020; 117:31808-31816. [PMID: 33257538 DOI: 10.1073/pnas.2010906117] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The universally conserved Sec system is the primary method cells utilize to transport proteins across membranes. Until recently, measuring the activity-a prerequisite for understanding how biological systems work-has been limited to discontinuous protein transport assays with poor time resolution or reported by large, nonnatural tags that perturb the process. The development of an assay based on a split superbright luciferase (NanoLuc) changed this. Here, we exploit this technology to unpick the steps that constitute posttranslational protein transport in bacteria. Under the conditions deployed, the transport of a model preprotein substrate (proSpy) occurs at 200 amino acids (aa) per minute, with SecA able to dissociate and rebind during transport. Prior to that, there is no evidence for a distinct, rate-limiting initiation event. Kinetic modeling suggests that SecA-driven transport activity is best described by a series of large (∼30 aa) steps, each coupled to hundreds of ATP hydrolysis events. The features we describe are consistent with a nondeterministic motor mechanism, such as a Brownian ratchet.
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30
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Antón Z, Mullally G, Ford HC, van der Kamp MW, Szczelkun MD, Lane JD. Mitochondrial import, health and mtDNA copy number variability seen when using type II and type V CRISPR effectors. J Cell Sci 2020; 133:jcs.248468. [PMID: 32843580 DOI: 10.1242/jcs.248468] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 08/10/2020] [Indexed: 12/18/2022] Open
Abstract
Current methodologies for targeting the mitochondrial genome for research and/or therapy development in mitochondrial diseases are restricted by practical limitations and technical inflexibility. A molecular toolbox for CRISPR-mediated mitochondrial genome editing is desirable, as this could enable targeting of mtDNA haplotypes using the precision and tuneability of CRISPR enzymes. Such 'MitoCRISPR' systems described to date lack reproducibility and independent corroboration. We have explored the requirements for MitoCRISPR in human cells by CRISPR nuclease engineering, including the use of alternative mitochondrial protein targeting sequences and smaller paralogues, and the application of guide (g)RNA modifications for mitochondrial import. We demonstrate varied mitochondrial targeting efficiencies and effects on mitochondrial dynamics/function of different CRISPR nucleases, with Lachnospiraceae bacterium ND2006 (Lb) Cas12a being better targeted and tolerated than Cas9 variants. We also provide evidence of Cas9 gRNA association with mitochondria in HeLa cells and isolated yeast mitochondria, even in the absence of a targeting RNA aptamer. Our data link mitochondrial-targeted LbCas12a/crRNA with increased mtDNA copy number dependent upon DNA binding and cleavage activity. We discuss reproducibility issues and the future steps necessary for MitoCRISPR.
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Affiliation(s)
- Zuriñe Antón
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Grace Mullally
- DNA-Protein Interactions Unit, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Holly C Ford
- DNA-Protein Interactions Unit, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Marc W van der Kamp
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK.,Centre for Computational Chemistry, School of Chemistry, Faculty of Science, University of Bristol, Bristol BS8 1TD, UK.,BrisSynBio, Life Sciences Building, Tyndall Avenue, University of Bristol, Bristol BS8 1TQ, UK
| | - Mark D Szczelkun
- DNA-Protein Interactions Unit, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK .,BrisSynBio, Life Sciences Building, Tyndall Avenue, University of Bristol, Bristol BS8 1TQ, UK
| | - Jon D Lane
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK .,BrisSynBio, Life Sciences Building, Tyndall Avenue, University of Bristol, Bristol BS8 1TQ, UK
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31
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Wagstaff JM, Balmforth M, Lewis N, Dods R, Rowland C, van Rietschoten K, Chen L, Harrison H, Skynner MJ, Dawson M, Ivanova-Berndt G, Beswick P. An Assay for Periplasm Entry Advances the Development of Chimeric Peptide Antibiotics. ACS Infect Dis 2020; 6:2355-2361. [PMID: 32697574 DOI: 10.1021/acsinfecdis.0c00389] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The treatment of infection by Gram-negative bacteria is increasingly challenging as resistance to existing antibiotics spreads. Constrained peptides, selected for high target specificity and affinity via library display technologies, are an emerging therapeutic modality in many disease areas and may be a fertile source of new antibiotics. Currently, the utility of constrained peptides and other large molecules as antibiotics is limited by the outer membrane (OM) barrier of Gram-negative bacteria. However, the addition of certain moieties to large molecules can confer the ability to cross the OM; these moieties function as intramolecular trans-OM "vectors". Here, we present a method to systematically assess the carrying capacity of candidate trans-OM vectors using a real-time luminescence assay ("SLALOM", Split Luciferase Assay for Live monitoring of Outer Membrane transit), reporting on periplasmic entry. We demonstrate the usefulness of our tools by constructing a 3800 Da chimeric compound composed of a constrained bicyclic peptide (Bicycle) with a periplasmic target, linked to an intramolecular peptide vector; the resulting chimera is a broad-spectrum inhibitor of pathogenic Gram-negative bacterial growth.
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Affiliation(s)
- James M. Wagstaff
- Bicycle Therapeutics, B900 Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | - Matthew Balmforth
- Bicycle Therapeutics, B900 Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | - Nick Lewis
- Bicycle Therapeutics, B900 Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | - Rachel Dods
- Bicycle Therapeutics, B900 Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | - Catherine Rowland
- Bicycle Therapeutics, B900 Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | | | - Liuhong Chen
- Bicycle Therapeutics, B900 Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | - Helen Harrison
- Bicycle Therapeutics, B900 Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | - Michael J. Skynner
- Bicycle Therapeutics, B900 Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | - Michael Dawson
- Bicycle Therapeutics, B900 Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | | | - Paul Beswick
- Bicycle Therapeutics, B900 Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
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32
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The SecA motor generates mechanical force during protein translocation. Nat Commun 2020; 11:3802. [PMID: 32732903 PMCID: PMC7393111 DOI: 10.1038/s41467-020-17561-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 07/07/2020] [Indexed: 12/31/2022] Open
Abstract
The Sec translocon moves proteins across lipid bilayers in all cells. The Sec channel enables passage of unfolded proteins through the bacterial plasma membrane, driven by the cytosolic ATPase SecA. Whether SecA generates mechanical force to overcome barriers to translocation posed by structured substrate proteins is unknown. Here, we kinetically dissect Sec-dependent translocation by monitoring translocation of a folded substrate protein with tunable stability at high time resolution. We find that substrate unfolding constitutes the rate-limiting step during translocation. Using single-molecule force spectroscopy, we also define the response of the protein to mechanical force. Relating the kinetic and force measurements reveals that SecA generates at least 10 piconewtons of mechanical force to actively unfold translocating proteins, comparable to cellular unfoldases. Combining biochemical and single-molecule measurements thus allows us to define how the SecA motor ensures efficient and robust export of proteins that contain stable structure. The ATPase SecA drives Sec-dependent protein translocation across the bacterial plasma membrane. Here, the authors combine kinetic translocation measurements with single-molecule force spectroscopy and demonstrate that the SecA motor generates mechanical force to unfold and translocate preproteins.
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33
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Westerhausen S, Nowak M, Torres‐Vargas CE, Bilitewski U, Bohn E, Grin I, Wagner S. A NanoLuc luciferase‐based assay enabling the real‐time analysis of protein secretion and injection by bacterial type III secretion systems. Mol Microbiol 2020; 113:1240-1254. [DOI: 10.1111/mmi.14490] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 02/11/2020] [Accepted: 02/15/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Sibel Westerhausen
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT) University of Tübingen Tübingen Germany
| | - Melanie Nowak
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT) University of Tübingen Tübingen Germany
- Partner‐site Tübingen German Center for Infection Research (DZIF) Tübingen Germany
| | - Claudia E. Torres‐Vargas
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT) University of Tübingen Tübingen Germany
| | | | - Erwin Bohn
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT) University of Tübingen Tübingen Germany
| | - Iwan Grin
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT) University of Tübingen Tübingen Germany
- Partner‐site Tübingen German Center for Infection Research (DZIF) Tübingen Germany
| | - Samuel Wagner
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT) University of Tübingen Tübingen Germany
- Partner‐site Tübingen German Center for Infection Research (DZIF) Tübingen Germany
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34
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Farhana I, Hossain MN, Suzuki K, Matsuda T, Nagai T. Genetically Encoded Fluorescence/Bioluminescence Bimodal Indicators for Ca 2+ Imaging. ACS Sens 2019; 4:1825-1834. [PMID: 31276380 DOI: 10.1021/acssensors.9b00531] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Fluorescent and bioluminescent genetically encoded Ca2+ indicators (GECIs) are an indispensable tool for monitoring Ca2+ dynamics in numerous cellular events. Although fluorescent GECIs have a high spatiotemporal resolution, their application is often confined to short-term imaging due to the external illumination that causes phototoxicity and autofluorescence from specimens. Bioluminescent GECIs overcome these pitfalls with enhanced compatibility to optogenetic manipulation and photophysiological processes; however, they are compromised for spatiotemporal resolution. Therefore, there has been a push toward the use of Ca2+ indicators that possess the advantages of both fluorescent and bioluminescent GECI for a wide range of applications. To address this, we developed a high-affinity bimodal GECI, GLICO, using a single fluorescent protein-based GECI combined with a split luciferase. Through this novel design, the fusion protein becomes bimodal and possesses Ca2+ sensing properties similar to those of its fluorescent ancestor and confers bioluminescence-based Ca2+ imaging. GLICO in bioluminescence mode has the highest dynamic range (2200%) of all bioluminescent GECIs. We demonstrated the performance of GLICO in studying cytosolic Ca2+ dynamics in different cultured cells in each mode. With the purpose of Ca2+ imaging in high Ca2+ content organelle, we also created a low-affinity variant, ReBLICO and performed Ca2+ imaging of the ER in both fluorescence and bioluminescence modes. The ability to switch between fluorescence and bioluminescence modes with a single indicator would benefit transgenic applications by presenting an opportunity for a wide range of live Ca2+ imaging in physiological and pathophysiological conditions.
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Affiliation(s)
- Israt Farhana
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
| | - Md Nadim Hossain
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
| | - Kazushi Suzuki
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
| | - Tomoki Matsuda
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
- Department of Biomolecular Science and Engineering, The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki 567-0047, Japan
| | - Takeharu Nagai
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
- Department of Biomolecular Science and Engineering, The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki 567-0047, Japan
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