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Cossart P, Hacker J, Holden DH, Normark S, Vogel J. Meeting report 'Microbiology 2023: from single cell to microbiome and host', an international interacademy conference in Würzburg. MICROLIFE 2024; 5:uqae008. [PMID: 38665235 PMCID: PMC11044969 DOI: 10.1093/femsml/uqae008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 04/04/2024] [Indexed: 04/28/2024]
Abstract
On September 20-22 September 2023, the international conference 'Microbiology 2023: from single cell to microbiome and host' convened microbiologists from across the globe for a very successful symposium, showcasing cutting-edge research in the field. Invited lecturers delivered exceptional presentations covering a wide range of topics, with a major emphasis on phages and microbiomes, on the relevant bacteria within these ecosystems, and their multifaceted roles in diverse environments. Discussions also spanned the intricate analysis of fundamental bacterial processes, such as cell division, stress resistance, and interactions with phages. Organized by four renowned Academies, the German Leopoldina, the French Académie des sciences, the Royal Society UK, and the Royal Swedish Academy of Sciences, the symposium provided a dynamic platform for experts to share insights and discoveries, leaving participants inspired and eager to integrate new knowledge into their respective projects. The success of Microbiology 2023 prompted the decision to host the next quadrennial academic meeting in Sweden. This choice underscores the commitment to fostering international collaboration and advancing the frontiers of microbiological knowledge. The transition to Sweden promises to be an exciting step in the ongoing global dialogue and specific collaborations on microbiology, a field where researchers will continue to push the boundaries of knowledge, understanding, and innovation not only in health and disease but also in ecology.
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Affiliation(s)
| | - Jörg Hacker
- German National Academy of Science Leopoldina, Jägerberg 1, D-06108 Halle, Germany
| | - David H Holden
- Department of Infectious Disease, Centre for Bacterial Resistance Biology, Flowers Building, South Kensington Campus, Exhibition Road, Imperial College London, London SW7 2AZ, United Kingdom
| | - Staffan Normark
- Karolinska Institute, Tumor-och-cellbiologi, C1 Microbial Pathogenesis, 17177 Stockholm, Sweden
| | - Jörg Vogel
- Faculty of Medicine, Institute for Molecular Infection Biology (IMIB), University of Würzburg, D-97080 Würzburg, Germany
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Josef-Schneider-Str2/Gebaude D15; É. D-97080 Würzburg, Germany
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Garrett SR, Palmer T. The role of proteinaceous toxins secreted by Staphylococcus aureus in interbacterial competition. FEMS MICROBES 2024; 5:xtae006. [PMID: 38495077 PMCID: PMC10941976 DOI: 10.1093/femsmc/xtae006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Revised: 02/17/2024] [Accepted: 02/27/2024] [Indexed: 03/19/2024] Open
Abstract
Staphylococcus aureus is highly adapted to colonization of the mammalian host. In humans the primary site of colonization is the epithelium of the nasal cavity. A major barrier to colonization is the resident microbiota, which have mechanisms to exclude S. aureus. As such, S. aureus has evolved mechanisms to compete with other bacteria, one of which is through secretion of proteinaceous toxins. S. aureus strains collectively produce a number of well-characterized Class I, II, and IV bacteriocins as well as several bacteriocin-like substances, about which less is known. These bacteriocins have potent antibacterial activity against several Gram-positive organisms, with some also active against Gram-negative species. S. aureus bacteriocins characterized to date are sporadically produced, and often encoded on plasmids. More recently the type VII secretion system (T7SS) of S. aureus has also been shown to play a role in interbacterial competition. The T7SS is encoded by all S. aureus isolates and so may represent a more widespread mechanism of competition used by this species. T7SS antagonism is mediated by the secretion of large protein toxins, three of which have been characterized to date: a nuclease toxin, EsaD; a membrane depolarizing toxin, TspA; and a phospholipase toxin, TslA. Further study is required to decipher the role that these different types of secreted toxins play in interbacterial competition and colonization of the host.
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Affiliation(s)
- Stephen R Garrett
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Tracy Palmer
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
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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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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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Boardman ER, Palmer T, Alcock F. Interbacterial competition mediated by the type VIIb secretion system. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001420. [PMID: 38116759 PMCID: PMC10765036 DOI: 10.1099/mic.0.001420] [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: 10/11/2023] [Accepted: 12/06/2023] [Indexed: 12/21/2023]
Abstract
Successful occupancy of a given niche requires the colonising bacteria to interact extensively with the biotic and abiotic environment, including other resident microbes. Bacteria have evolved a range of protein secretion machines for this purpose with eleven such systems identified to date. The type VIIb secretion system (T7SSb) is utilised by Bacillota to secrete a range of protein substrates, including antibacterial toxins targeting closely related strains, and the system as a whole has been implicated in a range of activities such as iron acquisition, intercellular signalling, host colonisation and virulence. This review covers the components and secretion mechanism of the T7SSb, the substrates of these systems and their roles in Gram-positive bacteria, with a focus on interbacterial competition.
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Affiliation(s)
- Eleanor R. Boardman
- Microbes in Health and Disease Theme, Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Tracy Palmer
- Microbes in Health and Disease Theme, Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Felicity Alcock
- Microbes in Health and Disease Theme, Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
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