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Nie X, Li Q, Chen X, Onyango S, Xie J, Nie S. Bacterial extracellular vesicles: Vital contributors to physiology from bacteria to host. Microbiol Res 2024; 284:127733. [PMID: 38678680 DOI: 10.1016/j.micres.2024.127733] [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: 03/19/2024] [Revised: 04/15/2024] [Accepted: 04/18/2024] [Indexed: 05/01/2024]
Abstract
Bacterial extracellular vesicles (bEVs) represent spherical particles with diameters ranging from 20 to 400 nm filled with multiple parental bacteria-derived components, including proteins, nucleic acids, lipids, and other biomolecules. The production of bEVs facilitates bacteria interacting with their environment and exerting biological functions. It is increasingly evident that the bEVs play integral roles in both bacterial and host physiology, contributing to environmental adaptations to functioning as health promoters for their hosts. This review highlights the current state of knowledge on the composition, biogenesis, and diversity of bEVs and the mechanisms by which different bEVs elicit effects on bacterial physiology and host health. We posit that an in-depth exploration of the mechanistic aspects of bEVs activity is essential to elucidate their health-promoting effects on the host and may facilitate the translation of bEVs into applications as novel natural biological nanomaterials.
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Affiliation(s)
- Xinke Nie
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China
| | - Qiqiong Li
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China
| | - Xinyang Chen
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China
| | | | - Junhua Xie
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China.
| | - Shaoping Nie
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China.
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2
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Sangiorgio G, Nicitra E, Bivona D, Bonomo C, Bonacci P, Santagati M, Musso N, Bongiorno D, Stefani S. Interactions of Gram-Positive Bacterial Membrane Vesicles and Hosts: Updates and Future Directions. Int J Mol Sci 2024; 25:2904. [PMID: 38474151 DOI: 10.3390/ijms25052904] [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: 01/24/2024] [Revised: 02/26/2024] [Accepted: 02/29/2024] [Indexed: 03/14/2024] Open
Abstract
Extracellular vesicles (EVs) are lipid bilayers derived from cell membranes, released by both eukaryotic cells and bacteria into the extracellular environment. During production, EVs carry proteins, nucleic acids, and various compounds, which are then released. While Gram-positive bacteria were traditionally thought incapable of producing EVs due to their thick peptidoglycan cell walls, recent studies on membrane vesicles (MVs) in Gram-positive bacteria have revealed their significant role in bacterial physiology and disease progression. This review explores the current understanding of MVs in Gram-positive bacteria, including the characterization of their content and functions, as well as their interactions with host and bacterial cells. It offers a fresh perspective to enhance our comprehension of Gram-positive bacterial EVs.
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Affiliation(s)
- Giuseppe Sangiorgio
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95125 Catania, Italy
| | - Emanuele Nicitra
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95125 Catania, Italy
| | - Dalida Bivona
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95125 Catania, Italy
| | - Carmelo Bonomo
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95125 Catania, Italy
| | - Paolo Bonacci
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95125 Catania, Italy
| | - Maria Santagati
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95125 Catania, Italy
| | - Nicolò Musso
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95125 Catania, Italy
| | - Dafne Bongiorno
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95125 Catania, Italy
| | - Stefania Stefani
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95125 Catania, Italy
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3
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Saggu SK, Nath A, Kumar S. Myxobacteria: biology and bioactive secondary metabolites. Res Microbiol 2023; 174:104079. [PMID: 37169232 DOI: 10.1016/j.resmic.2023.104079] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 04/22/2023] [Accepted: 05/04/2023] [Indexed: 05/13/2023]
Abstract
Myxobacteria are Gram-negative eubacteria and they thrive in a variety of habitats including soil rich in organic matter, rotting wood, animal dung and marine environment. Myxobacteria are a promising source of new compounds associated with diverse bioactive spectrum and unique mode of action. The genome information of myxobacteria has revealed many orphan biosynthetic pathways indicating that these bacteria can be the source of several novel natural products. In this review, we highlight the biology of myxobacteria with emphasis on their habitat, life cycle, isolation methods and enlist all the bioactive secondary metabolites purified till date and their mode of action.
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Affiliation(s)
- Sandeep Kaur Saggu
- Department of Biotechnology, Kanya Maha Vidyalaya, Jalandhar, Punjab, India - 144004.
| | - Amar Nath
- University Centre of Excellence in Research, Baba Farid University of Health Sciences, Faridkot, Punjab India 151203.
| | - Shiv Kumar
- Guru Gobind Singh Medical College, Baba Farid University of Health Sciences, Faridkot, Punjab India 151203.
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4
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Luo R, Chang Y, Liang H, Zhang W, Song Y, Li G, Yang C. Interactions between extracellular vesicles and microbiome in human diseases: New therapeutic opportunities. IMETA 2023; 2:e86. [PMID: 38868436 PMCID: PMC10989913 DOI: 10.1002/imt2.86] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 12/21/2022] [Accepted: 01/14/2023] [Indexed: 06/14/2024]
Abstract
In recent decades, accumulating research on the interactions between microbiome homeostasis and host health has broadened new frontiers in delineating the molecular mechanisms of disease pathogenesis and developing novel therapeutic strategies. By transporting proteins, nucleic acids, lipids, and metabolites in their versatile bioactive molecules, extracellular vesicles (EVs), natural bioactive cell-secreted nanoparticles, may be key mediators of microbiota-host communications. In addition to their positive and negative roles in diverse physiological and pathological processes, there is considerable evidence to implicate EVs secreted by bacteria (bacterial EVs [BEVs]) in the onset and progression of various diseases, including gastrointestinal, respiratory, dermatological, neurological, and musculoskeletal diseases, as well as in cancer. Moreover, an increasing number of studies have explored BEV-based platforms to design novel biomedical diagnostic and therapeutic strategies. Hence, in this review, we highlight the recent advances in BEV biogenesis, composition, biofunctions, and their potential involvement in disease pathologies. Furthermore, we introduce the current and emerging clinical applications of BEVs in diagnostic analytics, vaccine design, and novel therapeutic development.
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Affiliation(s)
- Rongjin Luo
- Department of Orthopaedics, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
- Department of Spine Surgery, Honghui HospitalXi'an Jiaotong UniversityXi'anChina
| | - Yanmin Chang
- Department of Neurology, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
| | - Huaizhen Liang
- Department of Orthopaedics, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
| | - Weifeng Zhang
- Department of Orthopaedics, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
| | - Yu Song
- Department of Orthopaedics, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
| | - Gaocai Li
- Department of Orthopaedics, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
| | - Cao Yang
- Department of Orthopaedics, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
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5
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Zwarycz AS, Page T, Nikolova G, Radford EJ, Whitworth DE. Predatory Strategies of Myxococcus xanthus: Prey Susceptibility to OMVs and Moonlighting Enzymes. Microorganisms 2023; 11:microorganisms11040874. [PMID: 37110297 PMCID: PMC10141889 DOI: 10.3390/microorganisms11040874] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 03/24/2023] [Accepted: 03/25/2023] [Indexed: 03/31/2023] Open
Abstract
Predatory outer membrane vesicles (OMVs) secreted by myxobacteria fuse readily with the outer membranes of Gram-negative bacteria, introducing toxic cargo into their prey. Here we used a strain of the myxobacterium Myxococcus xanthus that produces fluorescent OMVs to assay the uptake of OMVs by a panel of Gram-negative bacteria. M. xanthus strains took up significantly less OMV material than the tested prey strains, suggesting that re-fusion of OMVs with producing organisms is somehow inhibited. The OMV killing activity against different prey correlated strongly with the predatory activity of myxobacterial cells, however, there was no correlation between OMV killing activity and their propensity to fuse with different prey. It has previously been proposed that M. xanthus GAPDH stimulates the predatory activity of OMVs by enhancing OMV fusion with prey cells. Therefore, we expressed and purified active fusion proteins of M. xanthus glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate kinase (GAPDH and PGK; moonlighting enzymes with additional activities beyond their roles in glycolysis/gluconeogenesis) to investigate any involvement in OMV-mediated predation. Neither GAPDH nor PGK caused lysis of prey cells or enhanced OMV-mediated lysis of prey cells. However, both enzymes were found to inhibit the growth of Escherichia coli, even in the absence of OMVs. Our results suggest that fusion efficiency is not a determinant of prey killing, but instead resistance to the cargo of OMVs and co-secreted enzymes dictates whether organisms can be preyed upon by myxobacteria.
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6
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Pauli B, Ajmera S, Kost C. Determinants of synergistic cell-cell interactions in bacteria. Biol Chem 2023; 404:521-534. [PMID: 36859766 DOI: 10.1515/hsz-2022-0303] [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: 10/05/2022] [Accepted: 02/08/2023] [Indexed: 03/03/2023]
Abstract
Bacteria are ubiquitous and colonize virtually every conceivable habitat on earth. To achieve this, bacteria require different metabolites and biochemical capabilities. Rather than trying to produce all of the needed materials by themselves, bacteria have evolved a range of synergistic interactions, in which they exchange different commodities with other members of their local community. While it is widely acknowledged that synergistic interactions are key to the ecology of both individual bacteria and entire microbial communities, the factors determining their establishment remain poorly understood. Here we provide a comprehensive overview over our current knowledge on the determinants of positive cell-cell interactions among bacteria. Taking a holistic approach, we review the literature on the molecular mechanisms bacteria use to transfer commodities between bacterial cells and discuss to which extent these mechanisms favour or constrain the successful establishment of synergistic cell-cell interactions. In addition, we analyse how these different processes affect the specificity among interaction partners. By drawing together evidence from different disciplines that study the focal question on different levels of organisation, this work not only summarizes the state of the art in this exciting field of research, but also identifies new avenues for future research.
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Affiliation(s)
- Benedikt Pauli
- Department of Ecology, School of Biology/Chemistry, Osnabrück University, D-49076 Osnabrück, Germany
| | - Shiksha Ajmera
- Department of Ecology, School of Biology/Chemistry, Osnabrück University, D-49076 Osnabrück, Germany
| | - Christian Kost
- Department of Ecology, School of Biology/Chemistry, Osnabrück University, D-49076 Osnabrück, Germany.,Center of Cellular Nanoanalytics (CellNanOs), Osnabrück University, Barbarastrasse 11, D-49076 Osnabrück, Germany
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7
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Extracellular vesicles from phytobacteria: Properties, functions and uses. Biotechnol Adv 2022; 58:107934. [DOI: 10.1016/j.biotechadv.2022.107934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 02/25/2022] [Accepted: 02/26/2022] [Indexed: 11/20/2022]
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8
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Commensal and Pathogenic Bacterial-Derived Extracellular Vesicles in Host-Bacterial and Interbacterial Dialogues: Two Sides of the Same Coin. J Immunol Res 2022; 2022:8092170. [PMID: 35224113 PMCID: PMC8872691 DOI: 10.1155/2022/8092170] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 01/17/2022] [Accepted: 02/01/2022] [Indexed: 12/11/2022] Open
Abstract
Extracellular vesicles (EVs) cause effective changes in various domains of life. These bioactive structures are essential to the bidirectional organ communication. Recently, increasing research attention has been paid to EVs derived from commensal and pathogenic bacteria in their potential role to affect human disease risk for cancers and a variety of metabolic, gastrointestinal, psychiatric, and mental disorders. The present review presents an overview of both the protective and harmful roles of commensal and pathogenic bacteria-derived EVs in host-bacterial and interbacterial interactions. Bacterial EVs could impact upon human health by regulating microbiota–host crosstalk intestinal homeostasis, even in distal organs. The importance of vesicles derived from bacteria has been also evaluated regarding epigenetic modifications and applications. Generally, the evaluation of bacterial EVs is important towards finding efficient strategies for the prevention and treatment of various human diseases and maintaining metabolic homeostasis.
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9
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Modular Lipoprotein Toxins Transferred by Outer Membrane Exchange Target Discrete Cell Entry Pathways. mBio 2021; 12:e0238821. [PMID: 34517761 PMCID: PMC8546572 DOI: 10.1128/mbio.02388-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteria compete against related individuals by delivering toxins. In myxobacteria, a key delivery and kin discrimination mechanism is called outer membrane (OM) exchange (OME). Here, cells that display compatible polymorphic cell surface receptors recognize one another and bidirectionally transfer OM content. Included in the cargo is a suite of polymorphic SitA lipoprotein toxins. Consequently, OME between compatible cells that are not clonemates results in intoxication, while exchange between clonemates is harmonious because cells express a cognate repertoire of immunity proteins, which themselves are not transferred. SitA toxins belong to six nonhomologous families classified by sequence conservation within their N-terminal “escort domains” (EDs), while their C termini contain polymorphic nucleases that target the cytoplasmic compartment. To investigate how toxins delivered to the OM by OME translocate to the cytoplasm, we selected transposon mutants resistant to each family. Our screens identified eight genes that conferred resistance in a SitA family-specific manner. Most of these genes are predicted to localize to the cell envelope, and some resemble proteins that colicins exploit to gain cell entry. By constructing functional chimeric SitAs between families, we show that the ED determines the specificity of resistance. Importantly, a mutant that confers resistance to all six SitA families was discovered. This gene was named traC and plays an accessory role with traAB in OME. This work thus provides insight into the mechanism of kin discrimination in myxobacteria and provides working models for how SitA toxins exploit host proteins to gain cytoplasmic entry.
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10
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Phillips DA, Zacharoff LA, Hampton CM, Chong GW, Malanoski AP, Metskas LA, Xu S, Bird LJ, Eddie BJ, Miklos AE, Jensen GJ, Drummy LF, El-Naggar MY, Glaven SM. A bacterial membrane sculpting protein with BAR domain-like activity. eLife 2021; 10:60049. [PMID: 34643180 PMCID: PMC8687657 DOI: 10.7554/elife.60049] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 10/12/2021] [Indexed: 11/13/2022] Open
Abstract
Bin/Amphiphysin/RVS (BAR) domain proteins belong to a superfamily of coiled-coil proteins influencing membrane curvature in eukaryotes and are associated with vesicle biogenesis, vesicle-mediated protein trafficking, and intracellular signaling. Here, we report a bacterial protein with BAR domain-like activity, BdpA, from Shewanella oneidensis MR-1, known to produce redox-active membrane vesicles and micrometer-scale outer membrane extensions (OMEs). BdpA is required for uniform size distribution of membrane vesicles and influences scaffolding of OMEs into a consistent diameter and curvature. Cryo-TEM reveals that a strain lacking BdpA produces lobed, disordered OMEs rather than membrane tubules or narrow chains produced by the wild-type strain. Overexpression of BdpA promotes OME formation during planktonic growth of S. oneidensis where they are not typically observed. Heterologous expression results in OME production in Marinobacter atlanticus and Escherichia coli. Based on the ability of BdpA to alter membrane architecture in vivo, we propose that BdpA and its homologs comprise a newly identified class of bacterial BAR domain-like proteins.
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Affiliation(s)
- Daniel A Phillips
- Oak Ridge Institute for Science and Education / US Army DEVCOM Chemical Biological Center, Aberdeen Proving Grounds, United States
| | - Lori A Zacharoff
- Department of Physics and Astronomy, University of Southern California, Los Angeles, United States
| | - Cheri M Hampton
- Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Dayton, United States
| | - Grace W Chong
- Department of Biological Sciences, University of Southern California, Los Angeles, United States
| | - Anthony P Malanoski
- Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, Washington, United States
| | - Lauren Ann Metskas
- Biological Sciences, Chemistry, California Institute of Technology, Pasadena, United States
| | - Shuai Xu
- Department of Physics and Astronomy, University of Southern California, Los Angeles, United States
| | - Lina J Bird
- Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, Washington, United States
| | - Brian J Eddie
- Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, Washington, United States
| | - Aleksandr E Miklos
- BioSciences Division, BioChemistry Branch, US Army DEVCOM Chemical Biological Center, Aberdeen Proving Ground, United States
| | - Grant J Jensen
- Biology and Bioengineering, California Institute of Technology, Pasadena, United States
| | - Lawrence F Drummy
- Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Dayton, United States
| | - Mohamed Y El-Naggar
- Department of Physics and Astronomy, Biological Sciences, and Chemistry, University of Southern California, Los Angeles, United States
| | - Sarah M Glaven
- Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, Washington, United States
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11
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Matkó J, Tóth EA. Membrane nanotubes are ancient machinery for cell-to-cell communication and transport. Their interference with the immune system. Biol Futur 2021; 72:25-36. [PMID: 34554502 PMCID: PMC7869423 DOI: 10.1007/s42977-020-00062-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Accepted: 12/21/2020] [Indexed: 12/27/2022]
Abstract
Nanotubular connections between mammalian cell types came into the focus only two decades ago, when “live cell super-resolution imaging” was introduced. Observations of these long-time overlooked structures led to understanding mechanisms of their growth/withdrawal and exploring some key genetic and signaling factors behind their formation. Unbelievable level of multiple supportive collaboration between tumor cells undergoing cytotoxic chemotherapy, cross-feeding” between independent bacterial strains or “cross-dressing” collaboration of immune cells promoting cellular immune response, all via nanotubes, have been explored recently. Key factors and "calling signals" determining the spatial directionality of their growth and their overall in vivo significance, however, still remained debated. Interestingly, prokaryotes, including even ancient archaebacteria, also seem to use such NT connections for intercellular communication. Herein, we will give a brief overview of current knowledge of membrane nanotubes and depict a simple model about their possible “historical role”.
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Affiliation(s)
- János Matkó
- Department of Immunology, Institute of Biology, Eötvös Loránd University, H-1117 Pázmány Péter sétány 1/C, Budapest, Hungary.
| | - Eszter Angéla Tóth
- ATRC Aurigon Toxicological Research Center, H-2120 Pálya utca 2, Dunakeszi, Hungary
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12
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Kaplan M, Chreifi G, Metskas LA, Liedtke J, Wood CR, Oikonomou CM, Nicolas WJ, Subramanian P, Zacharoff LA, Wang Y, Chang YW, Beeby M, Dobro MJ, Zhu Y, McBride MJ, Briegel A, Shaffer CL, Jensen GJ. In situ imaging of bacterial outer membrane projections and associated protein complexes using electron cryo-tomography. eLife 2021; 10:73099. [PMID: 34468314 PMCID: PMC8455137 DOI: 10.7554/elife.73099] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 08/23/2021] [Indexed: 12/19/2022] Open
Abstract
The ability to produce outer membrane projections in the form of tubular membrane extensions (MEs) and membrane vesicles (MVs) is a widespread phenomenon among diderm bacteria. Despite this, our knowledge of the ultrastructure of these extensions and their associated protein complexes remains limited. Here, we surveyed the ultrastructure and formation of MEs and MVs, and their associated protein complexes, in tens of thousands of electron cryo-tomograms of ~90 bacterial species that we have collected for various projects over the past 15 years (Jensen lab database), in addition to data generated in the Briegel lab. We identified outer MEs and MVs in 13 diderm bacterial species and classified several major ultrastructures: (1) tubes with a uniform diameter (with or without an internal scaffold), (2) tubes with irregular diameter, (3) tubes with a vesicular dilation at their tip, (4) pearling tubes, (5) connected chains of vesicles (with or without neck-like connectors), (6) budding vesicles and nanopods. We also identified several protein complexes associated with these MEs and MVs which were distributed either randomly or exclusively at the tip. These complexes include a secretin-like structure and a novel crown-shaped structure observed primarily in vesicles from lysed cells. In total, this work helps to characterize the diversity of bacterial membrane projections and lays the groundwork for future research in this field.
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Affiliation(s)
- Mohammed Kaplan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Georges Chreifi
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Lauren Ann Metskas
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Janine Liedtke
- Leiden University, Sylvius Laboratories, Leiden, Netherlands
| | - Cecily R Wood
- Department of Veterinary Science, University of Kentucky, Lexington, United States
| | - Catherine M Oikonomou
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - William J Nicolas
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Poorna Subramanian
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Lori A Zacharoff
- Department of Physics and Astronomy, University of Southern California, Los Angeles, United States
| | - Yuhang Wang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Yi-Wei Chang
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Morgan Beeby
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Yongtao Zhu
- Department of Biological Sciences, Minnesota State University, Mankato, United States
| | - Mark J McBride
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, United States
| | - Ariane Briegel
- Leiden University, Sylvius Laboratories, Leiden, Netherlands
| | - Carrie L Shaffer
- Department of Veterinary Science, University of Kentucky, Lexington, United States.,Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, United States.,Department of Pharmaceutical Sciences, University of Kentucky, Lexington, United States
| | - Grant J Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States.,Department of Chemistry and Biochemistry, Brigham Young University, Provo, United States
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13
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Pospíšil J, Vítovská D, Kofroňová O, Muchová K, Šanderová H, Hubálek M, Šiková M, Modrák M, Benada O, Barák I, Krásný L. Bacterial nanotubes as a manifestation of cell death. Nat Commun 2020; 11:4963. [PMID: 33009406 PMCID: PMC7532143 DOI: 10.1038/s41467-020-18800-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 09/03/2020] [Indexed: 12/18/2022] Open
Abstract
Bacterial nanotubes are membranous structures that have been reported to function as conduits between cells to exchange DNA, proteins, and nutrients. Here, we investigate the morphology and formation of bacterial nanotubes using Bacillus subtilis. We show that nanotube formation is associated with stress conditions, and is highly sensitive to the cells' genetic background, growth phase, and sample preparation methods. Remarkably, nanotubes appear to be extruded exclusively from dying cells, likely as a result of biophysical forces. Their emergence is extremely fast, occurring within seconds by cannibalizing the cell membrane. Subsequent experiments reveal that cell-to-cell transfer of non-conjugative plasmids depends strictly on the competence system of the cell, and not on nanotube formation. Our study thus supports the notion that bacterial nanotubes are a post mortem phenomenon involved in cell disintegration, and are unlikely to be involved in cytoplasmic content exchange between live cells.
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Affiliation(s)
- Jiří Pospíšil
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic
| | - Dragana Vítovská
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic
| | - Olga Kofroňová
- Laboratory of Molecular Structure Characterization, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic
| | - Katarína Muchová
- Department of Microbial Genetics, Institute of Molecular Biology, Slovak Academy of Sciences, 845 51, Bratislava, Slovakia
| | - Hana Šanderová
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic
| | - Martin Hubálek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 160 00, Prague 6, Czech Republic
| | - Michaela Šiková
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic
| | - Martin Modrák
- Laboratory of Bioinformatics/Core Facility, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic
| | - Oldřich Benada
- Laboratory of Molecular Structure Characterization, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic.
| | - Imrich Barák
- Department of Microbial Genetics, Institute of Molecular Biology, Slovak Academy of Sciences, 845 51, Bratislava, Slovakia.
| | - Libor Krásný
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic.
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14
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Cao P, Wall D. The Fluidity of the Bacterial Outer Membrane Is Species Specific: Bacterial Lifestyles and the Emergence of a Fluid Outer Membrane. Bioessays 2020; 42:e1900246. [PMID: 32363627 PMCID: PMC7392792 DOI: 10.1002/bies.201900246] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 03/23/2020] [Indexed: 01/17/2023]
Abstract
The outer membrane (OM) is an essential barrier that guards Gram-negative bacteria from diverse environmental insults. Besides functioning as a chemical gatekeeper, the OM also contributes towards the strength and stiffness of cells and allows them to sustain mechanical stress. Largely influenced by studies of Escherichia coli, the OM is viewed as a rigid barrier where OM proteins and lipopolysaccharides display restricted mobility. Here the discussion is extended to other bacterial species, with a focus on Myxococcus xanthus. In contrast to the rigid OM paradigm, myxobacteria possess a relatively fluid OM. It is concluded that the fluidity of the OM varies across environmental species, which is likely linked to their evolution and adaptation to specific ecological niches. Importantly, a fluid OM can endow bacteria with distinct functions for cell-cell and cell-environment interactions.
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Affiliation(s)
| | - Daniel Wall
- Department of Molecular Biology, University of Wyoming, 1000 E University Avenue, Laramie, WY, 82071, USA
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Singhi D, Srivastava P. Role of Bacterial Cytoskeleton and Other Apparatuses in Cell Communication. Front Mol Biosci 2020; 7:158. [PMID: 32766280 PMCID: PMC7378377 DOI: 10.3389/fmolb.2020.00158] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 06/24/2020] [Indexed: 11/13/2022] Open
Abstract
The bacterial cytoskeleton is crucial for sensing the external environment and plays a major role in cell to cell communication. There are several other apparatuses such as conjugation tubes, membrane vesicles, and nanotubes used by bacterial cells for communication. The present review article describes the various bacterial cytoskeletal proteins and other apparatuses, the physical structures they form and their role in sensing environmental stress. The implications of this cellular communication in pathogenicity are discussed.
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Affiliation(s)
| | - Preeti Srivastava
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, New Delhi, India
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16
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Galkina SI, Fedorova NV, Golenkina EA, Stadnichuk VI, Sud’ina GF. Cytonemes Versus Neutrophil Extracellular Traps in the Fight of Neutrophils with Microbes. Int J Mol Sci 2020; 21:ijms21020586. [PMID: 31963289 PMCID: PMC7014225 DOI: 10.3390/ijms21020586] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 12/11/2022] Open
Abstract
Neutrophils can phagocytose microorganisms and destroy them intracellularly using special bactericides located in intracellular granules. Recent evidence suggests that neutrophils can catch and kill pathogens extracellularly using the same bactericidal agents. For this, live neutrophils create a cytoneme network, and dead neutrophils provide chromatin and proteins to form neutrophil extracellular traps (NETs). Cytonemes are filamentous tubulovesicular secretory protrusions of living neutrophils with intact nuclei. Granular bactericides are localized in membrane vesicles and tubules of which cytonemes are composed. NETs are strands of decondensed DNA associated with histones released by died neutrophils. In NETs, bactericidal neutrophilic agents are adsorbed onto DNA strands and are not covered with a membrane. Cytonemes and NETs occupy different places in protecting the body against infections. Cytonemes can develop within a few minutes at the site of infection through the action of nitric oxide or actin-depolymerizing alkaloids of invading microbes. The formation of NET in vitro occurs due to chromatin decondensation resulting from prolonged activation of neutrophils with PMA (phorbol 12-myristate 13-acetate) or other stimuli, or in vivo due to citrullination of histones with peptidylarginine deiminase 4. In addition to antibacterial activity, cytonemes are involved in cell adhesion and communications. NETs play a role in autoimmunity and thrombosis.
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Affiliation(s)
- Svetlana I. Galkina
- Lomonosov Moscow State University, A. N. Belozersky Institute of Physico-Chemical Biology, 119991 Moscow, Russia; (N.V.F.); (E.A.G.)
- Correspondence: (S.I.G.); (G.F.S.); Tel.: +7-495-939-5408 (S.I.G.)
| | - Natalia V. Fedorova
- Lomonosov Moscow State University, A. N. Belozersky Institute of Physico-Chemical Biology, 119991 Moscow, Russia; (N.V.F.); (E.A.G.)
| | - Ekaterina A. Golenkina
- Lomonosov Moscow State University, A. N. Belozersky Institute of Physico-Chemical Biology, 119991 Moscow, Russia; (N.V.F.); (E.A.G.)
| | | | - Galina F. Sud’ina
- Lomonosov Moscow State University, A. N. Belozersky Institute of Physico-Chemical Biology, 119991 Moscow, Russia; (N.V.F.); (E.A.G.)
- Correspondence: (S.I.G.); (G.F.S.); Tel.: +7-495-939-5408 (S.I.G.)
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Thiery S, Kaimer C. The Predation Strategy of Myxococcus xanthus. Front Microbiol 2020; 11:2. [PMID: 32010119 PMCID: PMC6971385 DOI: 10.3389/fmicb.2020.00002] [Citation(s) in RCA: 78] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 01/03/2020] [Indexed: 11/20/2022] Open
Abstract
Myxobacteria are ubiquitous in soil environments. They display a complex life cycle: vegetatively growing cells coordinate their motility to form multicellular swarms, which upon starvation aggregate into large fruiting bodies where cells differentiate into spores. In addition to growing as saprophytes, Myxobacteria are predators that actively kill bacteria of other species to consume their biomass. In this review, we summarize research on the predation behavior of the model myxobacterium Myxococcus xanthus, which can access nutrients from a broad spectrum of microorganisms. M. xanthus displays an epibiotic predation strategy, i.e., it induces prey lysis from the outside and feeds on the released biomass. This predatory behavior encompasses various processes: Gliding motility and induced cell reversals allow M. xanthus to encounter prey and to remain within the area to sweep up its biomass, which causes the characteristic “rippling” of preying populations. Antibiotics and secreted bacteriolytic enzymes appear to be important predation factors, which are possibly targeted to prey cells with the aid of outer membrane vesicles. However, certain bacteria protect themselves from M. xanthus predation by forming mechanical barriers, such as biofilms and mucoid colonies, or by secreting antibiotics. Further understanding the molecular mechanisms that mediate myxobacterial predation will offer fascinating insight into the reciprocal relationships of bacteria in complex communities, and might spur application-oriented research on the development of novel antibacterial strategies.
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Affiliation(s)
- Susanne Thiery
- Department of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Christine Kaimer
- Department of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
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Goes A, Lapuhs P, Kuhn T, Schulz E, Richter R, Panter F, Dahlem C, Koch M, Garcia R, Kiemer AK, Müller R, Fuhrmann G. Myxobacteria-Derived Outer Membrane Vesicles: Potential Applicability Against Intracellular Infections. Cells 2020; 9:cells9010194. [PMID: 31940898 PMCID: PMC7017139 DOI: 10.3390/cells9010194] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 01/07/2020] [Accepted: 01/08/2020] [Indexed: 12/22/2022] Open
Abstract
In 2019, it was estimated that 2.5 million people die from lower tract respiratory infections annually. One of the main causes of these infections is Staphylococcus aureus, a bacterium that can invade and survive within mammalian cells. S. aureus intracellular infections are difficult to treat because several classes of antibiotics are unable to permeate through the cell wall and reach the pathogen. This condition increases the need for new therapeutic avenues, able to deliver antibiotics efficiently. In this work, we obtained outer membrane vesicles (OMVs) derived from the myxobacteria Cystobacter velatus strain Cbv34 and Cystobacter ferrugineus strain Cbfe23, that are naturally antimicrobial, to target intracellular infections, and investigated how they can affect the viability of epithelial and macrophage cell lines. We evaluated by cytometric bead array whether they induce the expression of proinflammatory cytokines in blood immune cells. Using confocal laser scanning microscopy and flow cytometry, we also investigated their interaction and uptake into mammalian cells. Finally, we studied the effect of OMVs on planktonic and intracellular S. aureus. We found that while Cbv34 OMVs were not cytotoxic to cells at any concentration tested, Cbfe23 OMVs affected the viability of macrophages, leading to a 50% decrease at a concentration of 125,000 OMVs/cell. We observed only little to moderate stimulation of release of TNF-alpha, IL-8, IL-6 and IL-1beta by both OMVs. Cbfe23 OMVs have better interaction with the cells than Cbv34 OMVs, being taken up faster by them, but both seem to remain mostly on the cell surface after 24 h of incubation. This, however, did not impair their bacteriostatic activity against intracellular S. aureus. In this study, we provide an important basis for implementing OMVs in the treatment of intracellular infections.
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Affiliation(s)
- Adriely Goes
- Helmholtz Centre for Infection Research (HZI), Biogenic Nanotherapeutics Group (BION), Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany; (A.G.); (P.L.); (T.K.); (E.S.)
- Department of Pharmacy, Saarland University, Campus Building E8.1, 66123 Saarbrücken, Germany; (R.R.); (R.M.)
| | - Philipp Lapuhs
- Helmholtz Centre for Infection Research (HZI), Biogenic Nanotherapeutics Group (BION), Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany; (A.G.); (P.L.); (T.K.); (E.S.)
- Department of Pharmacy, Saarland University, Campus Building E8.1, 66123 Saarbrücken, Germany; (R.R.); (R.M.)
| | - Thomas Kuhn
- Helmholtz Centre for Infection Research (HZI), Biogenic Nanotherapeutics Group (BION), Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany; (A.G.); (P.L.); (T.K.); (E.S.)
- Department of Pharmacy, Saarland University, Campus Building E8.1, 66123 Saarbrücken, Germany; (R.R.); (R.M.)
| | - Eilien Schulz
- Helmholtz Centre for Infection Research (HZI), Biogenic Nanotherapeutics Group (BION), Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany; (A.G.); (P.L.); (T.K.); (E.S.)
- Department of Pharmacy, Saarland University, Campus Building E8.1, 66123 Saarbrücken, Germany; (R.R.); (R.M.)
| | - Robert Richter
- Department of Pharmacy, Saarland University, Campus Building E8.1, 66123 Saarbrücken, Germany; (R.R.); (R.M.)
- Helmholtz Centre for Infection Research (HZI), Department of Drug Delivery (DDEL), Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany
| | - Fabian Panter
- Helmholtz Centre for Infection Research (HZI), Department of Microbial Natural Products (MINS), Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany; (F.P.); (R.G.)
| | - Charlotte Dahlem
- Department of Pharmacy, Pharmaceutical Biology, Saarland University, 66123 Saarbrücken, Germany; (C.D.); (A.K.K.)
| | - Marcus Koch
- INM-Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany;
| | - Ronald Garcia
- Helmholtz Centre for Infection Research (HZI), Department of Microbial Natural Products (MINS), Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany; (F.P.); (R.G.)
| | - Alexandra K. Kiemer
- Department of Pharmacy, Pharmaceutical Biology, Saarland University, 66123 Saarbrücken, Germany; (C.D.); (A.K.K.)
| | - Rolf Müller
- Department of Pharmacy, Saarland University, Campus Building E8.1, 66123 Saarbrücken, Germany; (R.R.); (R.M.)
- Helmholtz Centre for Infection Research (HZI), Department of Microbial Natural Products (MINS), Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany; (F.P.); (R.G.)
- German Center for Infection Research (DZIF), 38124 Braunschweig, Germany
| | - Gregor Fuhrmann
- Helmholtz Centre for Infection Research (HZI), Biogenic Nanotherapeutics Group (BION), Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany; (A.G.); (P.L.); (T.K.); (E.S.)
- Department of Pharmacy, Saarland University, Campus Building E8.1, 66123 Saarbrücken, Germany; (R.R.); (R.M.)
- Correspondence: ; Tel.: +49-68-198-806 (ext. 1500)
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Drab M, Stopar D, Kralj-Iglič V, Iglič A. Inception Mechanisms of Tunneling Nanotubes. Cells 2019; 8:cells8060626. [PMID: 31234435 PMCID: PMC6627088 DOI: 10.3390/cells8060626] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 06/18/2019] [Accepted: 06/18/2019] [Indexed: 01/13/2023] Open
Abstract
Tunneling nanotubes (TNTs) are thin membranous tubes that interconnect cells, representing a novel route of cell-to-cell communication and spreading of pathogens. TNTs form between many cell types, yet their inception mechanisms remain elusive. We review in this study general concepts related to the formation and stability of membranous tubular structures with a focus on a deviatoric elasticity model of membrane nanodomains. We review experimental evidence that tubular structures initiate from local membrane bending facilitated by laterally distributed proteins or anisotropic membrane nanodomains. We further discuss the numerical results of several theoretical and simulation models of nanodomain segregation suggesting the mechanisms of TNT inception and stability. We discuss the coupling of nanodomain segregation with the action of protruding cytoskeletal forces, which are mostly provided in eukaryotic cells by the polymerization of f-actin, and review recent inception mechanisms of TNTs in relation to motor proteins.
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Affiliation(s)
- Mitja Drab
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana,1000 Ljubljana, Slovenia.
- Laboratory of Clinical Biophysics, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia.
| | - David Stopar
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia.
| | - Veronika Kralj-Iglič
- Laboratory of Clinical Biophysics, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia.
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, 1000 Ljubljana, Slovenia.
| | - Aleš Iglič
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana,1000 Ljubljana, Slovenia.
- Laboratory of Clinical Biophysics, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia.
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20
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Gill S, Catchpole R, Forterre P. Extracellular membrane vesicles in the three domains of life and beyond. FEMS Microbiol Rev 2019; 43:273-303. [PMID: 30476045 PMCID: PMC6524685 DOI: 10.1093/femsre/fuy042] [Citation(s) in RCA: 264] [Impact Index Per Article: 52.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 11/20/2018] [Indexed: 02/06/2023] Open
Abstract
Cells from all three domains of life, Archaea, Bacteria and Eukarya, produce extracellular vesicles (EVs) which are sometimes associated with filamentous structures known as nanopods or nanotubes. The mechanisms of EV biogenesis in the three domains remain poorly understood, although studies in Bacteria and Eukarya indicate that the regulation of lipid composition plays a major role in initiating membrane curvature. EVs are increasingly recognized as important mediators of intercellular communication via transfer of a wide variety of molecular cargoes. They have been implicated in many aspects of cell physiology such as stress response, intercellular competition, lateral gene transfer (via RNA or DNA), pathogenicity and detoxification. Their role in various human pathologies and aging has aroused much interest in recent years. EVs can be used as decoys against viral attack but virus-infected cells also produce EVs that boost viral infection. Here, we review current knowledge on EVs in the three domains of life and their interactions with the viral world.
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Affiliation(s)
- Sukhvinder Gill
- Institute for Integrative Biology of the Cell (I2BC), Biologie Cellulaire des Archées (BCA), CEA, CNRS, Université Paris-Sud, 91405 Orsay cedex, France
| | - Ryan Catchpole
- Institut Pasteur, Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, Département de Microbiologie, F75015 Paris, France
| | - Patrick Forterre
- Institute for Integrative Biology of the Cell (I2BC), Biologie Cellulaire des Archées (BCA), CEA, CNRS, Université Paris-Sud, 91405 Orsay cedex, France
- Institut Pasteur, Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, Département de Microbiologie, F75015 Paris, France
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21
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Bhattacharya S, Baidya AK, Pal RR, Mamou G, Gatt YE, Margalit H, Rosenshine I, Ben-Yehuda S. A Ubiquitous Platform for Bacterial Nanotube Biogenesis. Cell Rep 2019; 27:334-342.e10. [PMID: 30929979 PMCID: PMC6456723 DOI: 10.1016/j.celrep.2019.02.055] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 02/05/2019] [Accepted: 02/13/2019] [Indexed: 01/01/2023] Open
Abstract
We have previously described the existence of membranous nanotubes, bridging adjacent bacteria, facilitating intercellular trafficking of nutrients, cytoplasmic proteins, and even plasmids, yet components enabling their biogenesis remain elusive. Here we reveal the identity of a molecular apparatus providing a platform for nanotube biogenesis. Using Bacillus subtilis (Bs), we demonstrate that conserved components of the flagellar export apparatus (FliO, FliP, FliQ, FliR, FlhB, and FlhA), designated CORE, dually serve for flagellum and nanotube assembly. Mutants lacking CORE genes, but not other flagellar components, are deficient in both nanotube production and the associated intercellular molecular trafficking. In accord, CORE components are located at sites of nanotube emergence. Deleting COREs of distinct species established that CORE-mediated nanotube formation is widespread. Furthermore, exogenous COREs from diverse species could restore nanotube generation and functionality in Bs lacking endogenous CORE. Our results demonstrate that the CORE-derived nanotube is a ubiquitous organelle that facilitates intercellular molecular trade across the bacterial kingdom. Conserved flagellar CORE components dually serve for flagella and nanotube assembly CORE mutants are deficient in nanotube formation and intercellular molecular trade CORE-dependent nanotube production is conserved among distinct bacterial species The CORE-nanotube organelle can provide a common path for bacterial molecular trade
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Affiliation(s)
- Saurabh Bhattacharya
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, POB 12272, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel
| | - Amit K Baidya
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, POB 12272, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel
| | - Ritesh Ranjan Pal
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, POB 12272, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel
| | - Gideon Mamou
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, POB 12272, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel
| | - Yair E Gatt
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, POB 12272, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel
| | - Hanah Margalit
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, POB 12272, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel
| | - Ilan Rosenshine
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, POB 12272, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel.
| | - Sigal Ben-Yehuda
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, POB 12272, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel.
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22
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Toyofuku M, Nomura N, Eberl L. Types and origins of bacterial membrane vesicles. Nat Rev Microbiol 2018; 17:13-24. [DOI: 10.1038/s41579-018-0112-2] [Citation(s) in RCA: 396] [Impact Index Per Article: 66.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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23
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Baidya AK, Bhattacharya S, Dubey GP, Mamou G, Ben-Yehuda S. Bacterial nanotubes: a conduit for intercellular molecular trade. Curr Opin Microbiol 2018; 42:1-6. [DOI: 10.1016/j.mib.2017.08.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 08/23/2017] [Accepted: 08/28/2017] [Indexed: 12/01/2022]
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Ultrastructure of Shewanella oneidensis MR-1 nanowires revealed by electron cryotomography. Proc Natl Acad Sci U S A 2018; 115:E3246-E3255. [PMID: 29555764 DOI: 10.1073/pnas.1718810115] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bacterial nanowires have garnered recent interest as a proposed extracellular electron transfer (EET) pathway that links the bacterial electron transport chain to solid-phase electron acceptors away from the cell. Recent studies showed that Shewanella oneidensis MR-1 produces outer membrane (OM) and periplasmic extensions that contain EET components and hinted at their possible role as bacterial nanowires. However, their fine structure and distribution of cytochrome electron carriers under native conditions remained unclear, making it difficult to evaluate the potential electron transport (ET) mechanism along OM extensions. Here, we report high-resolution images of S. oneidensis OM extensions, using electron cryotomography (ECT). We developed a robust method for fluorescence light microscopy imaging of OM extension growth on electron microscopy grids and used correlative light and electron microscopy to identify and image the same structures by ECT. Our results reveal that S. oneidensis OM extensions are dynamic chains of interconnected outer membrane vesicles (OMVs) with variable dimensions, curvature, and extent of tubulation. Junction densities that potentially stabilize OMV chains are seen between neighboring vesicles in cryotomograms. By comparing wild type and a cytochrome gene deletion mutant, our ECT results provide the likely positions and packing of periplasmic and outer membrane proteins consistent with cytochromes. Based on the observed cytochrome packing density, we propose a plausible ET path along the OM extensions involving a combination of direct hopping and cytochrome diffusion. A mean-field calculation, informed by the observed ECT cytochrome density, supports this proposal by revealing ET rates on par with a fully packed cytochrome network.
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26
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Bretl DJ, Müller S, Ladd KM, Atkinson SN, Kirby JR. Type IV-pili dependent motility is co-regulated by PilSR and PilS2R2 two-component systems via distinct pathways in Myxococcus xanthus. Mol Microbiol 2016; 102:37-53. [PMID: 27393239 DOI: 10.1111/mmi.13445] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/16/2016] [Indexed: 01/08/2023]
Abstract
Myxococcus xanthus is an environmental bacterium with two forms of motility. One type, known as social motility, is dependent on extension and retraction of Type-IV pili (T4P) and production of extracellular polysaccharides (EPS). Several signaling systems have been linked to regulation of T4P-dependent motility. In particular, expression of the pilin subunit pilA requires the PilSR two-component signaling system (TCS). A second TCS, PilS2R2, encoded within the same locus that encodes PilSR, has also been linked to M. xanthus T4P-dependent motility. We demonstrate that PilSR and PilS2R2 regulate M. xanthus T4P-dependent motility through distinct pathways. Consistent with known roles of PilSR, our results indicate that the primary function of PilSR is to regulate expression of pilA. In contrast, PilS2 and PilR2 have little to no affect on PilA protein levels. However, deletion of pilR2 resulted in a reduction of assembled pili, significant decreases in EPS production and loss of T4P-dependent motility. Furthermore, the pilR2 mutation led to increased production of outer membrane vesicles (OMV). Collectively, we propose that PilS2R2 is required for proper assembly of T4P and regulation of OMV production, and hypothesize that production of these vesicles is related to M. xanthus motility.
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Affiliation(s)
- Daniel J Bretl
- Department of Microbiology, University of Iowa, 51 Newton Road, Iowa City, Iowa, 52242, USA
| | - Susanne Müller
- Department of Microbiology, University of Iowa, 51 Newton Road, Iowa City, Iowa, 52242, USA
| | - Kayla M Ladd
- Department of Microbiology, University of Iowa, 51 Newton Road, Iowa City, Iowa, 52242, USA
| | - Samantha N Atkinson
- Department of Microbiology, University of Iowa, 51 Newton Road, Iowa City, Iowa, 52242, USA
| | - John R Kirby
- Department of Microbiology, University of Iowa, 51 Newton Road, Iowa City, Iowa, 52242, USA.
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27
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Hickey WJ, Shetty AR, Massey RJ, Toso DB, Austin J. Three-dimensional bright-field scanning transmission electron microscopy elucidate novel nanostructure in microbial biofilms. J Microsc 2016; 265:3-10. [PMID: 27519057 DOI: 10.1111/jmi.12455] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Revised: 05/17/2016] [Accepted: 07/18/2016] [Indexed: 01/03/2023]
Abstract
Bacterial biofilms play key roles in environmental and biomedical processes, and understanding their activities requires comprehension of their nanoarchitectural characteristics. Electron microscopy (EM) is an essential tool for nanostructural analysis, but conventional EM methods are limited in that they either provide topographical information alone, or are suitable for imaging only relatively thin (<300 nm) sample volumes. For biofilm investigations, these are significant restrictions. Understanding structural relations between cells requires imaging of a sample volume sufficiently large to encompass multiple cells and the capture of both external and internal details of cell structure. An emerging EM technique with such capabilities is bright-field scanning transmission electron microscopy (BF-STEM) and in the present report BF-STEM was coupled with tomography to elucidate nanostructure in biofilms formed by the polycyclic aromatic hydrocarbon-degrading soil bacterium, Delftia acidovorans Cs1-4. Dual-axis BF-STEM enabled high-resolution 3-D tomographic recontructions (6-10 nm) visualization of thick (1250 and 1500 nm) sections. The 3-D data revealed that novel extracellular structures, termed nanopods, were polymorphic and formed complex networks within cell clusters. BF-STEM tomography enabled visualization of conduits formed by nanopods that could enable intercellular movement of outer membrane vesicles, and thereby enable direct communication between cells. This report is the first to document application of dual-axis BF-STEM tomography to obtain high-resolution 3-D images of novel nanostructures in bacterial biofilms. Future work with dual-axis BF-STEM tomography combined with correlative light electron microscopy may provide deeper insights into physiological functions associated with nanopods as well as other nanostructures.
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Affiliation(s)
- William J Hickey
- O.N. Allen Laboratory for Soil Microbiology, Department Soil Science, University of Wisconsin-Madison, Madison, Wisconsin, U.S.A
| | - Ameesha R Shetty
- O.N. Allen Laboratory for Soil Microbiology, Department Soil Science, University of Wisconsin-Madison, Madison, Wisconsin, U.S.A
| | - Randall J Massey
- Electron Microscope Facility, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, U.S.A
| | - Daniel B Toso
- O.N. Allen Laboratory for Soil Microbiology, Department Soil Science, University of Wisconsin-Madison, Madison, Wisconsin, U.S.A
| | - Jotham Austin
- Department Molecular Genetics and Cell Biology and Advanced Electron Microscopy Facility, University of Chicago, Chicago, Illinois, U.S.A
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Muñoz-Dorado J, Marcos-Torres FJ, García-Bravo E, Moraleda-Muñoz A, Pérez J. Myxobacteria: Moving, Killing, Feeding, and Surviving Together. Front Microbiol 2016; 7:781. [PMID: 27303375 PMCID: PMC4880591 DOI: 10.3389/fmicb.2016.00781] [Citation(s) in RCA: 199] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 05/09/2016] [Indexed: 11/13/2022] Open
Abstract
Myxococcus xanthus, like other myxobacteria, is a social bacterium that moves and feeds cooperatively in predatory groups. On surfaces, rod-shaped vegetative cells move in search of the prey in a coordinated manner, forming dynamic multicellular groups referred to as swarms. Within the swarms, cells interact with one another and use two separate locomotion systems. Adventurous motility, which drives the movement of individual cells, is associated with the secretion of slime that forms trails at the leading edge of the swarms. It has been proposed that cellular traffic along these trails contributes to M. xanthus social behavior via stigmergic regulation. However, most of the cells travel in groups by using social motility, which is cell contact-dependent and requires a large number of individuals. Exopolysaccharides and the retraction of type IV pili at alternate poles of the cells are the engines associated with social motility. When the swarms encounter prey, the population of M. xanthus lyses and takes up nutrients from nearby cells. This cooperative and highly density-dependent feeding behavior has the advantage that the pool of hydrolytic enzymes and other secondary metabolites secreted by the entire group is shared by the community to optimize the use of the degradation products. This multicellular behavior is especially observed in the absence of nutrients. In this condition, M. xanthus swarms have the ability to organize the gliding movements of 1000s of rods, synchronizing rippling waves of oscillating cells, to form macroscopic fruiting bodies, with three subpopulations of cells showing division of labor. A small fraction of cells either develop into resistant myxospores or remain as peripheral rods, while the majority of cells die, probably to provide nutrients to allow aggregation and spore differentiation. Sporulation within multicellular fruiting bodies has the benefit of enabling survival in hostile environments, and increases germination and growth rates when cells encounter favorable conditions. Herein, we review how these social bacteria cooperate and review the main cell–cell signaling systems used for communication to maintain multicellularity.
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Affiliation(s)
- José Muñoz-Dorado
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada Granada, Spain
| | | | - Elena García-Bravo
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada Granada, Spain
| | - Aurelio Moraleda-Muñoz
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada Granada, Spain
| | - Juana Pérez
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada Granada, Spain
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Vassallo CN, Wall D. Tissue repair in myxobacteria: A cooperative strategy to heal cellular damage. Bioessays 2016; 38:306-15. [PMID: 26898360 DOI: 10.1002/bies.201500132] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Damage repair is a fundamental requirement of all life as organisms find themselves in challenging and fluctuating environments. In particular, damage to the barrier between an organism and its environment (e.g. skin, plasma membrane, bacterial cell envelope) is frequent because these organs/organelles directly interact with the external world. Here, we discuss the general strategies that bacteria use to cope with damage to their cell envelope and their repair limits. We then describe a novel damage-coping mechanism used by multicellular myxobacteria. We propose that cell-cell transfer of membrane material within a population serves as a wound-healing strategy and provide evidence for its utility. We suggest that--similar to how tissues in eukaryotes have evolved cooperative methods of damage repair--so too have some bacteria that live a multicellular lifestyle.
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Affiliation(s)
| | - Daniel Wall
- Department of Molecular Biology, University of Wyoming, Laramie, WY, USA
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Dubey G, Malli Mohan G, Dubrovsky A, Amen T, Tsipshtein S, Rouvinski A, Rosenberg A, Kaganovich D, Sherman E, Medalia O, Ben-Yehuda S. Architecture and Characteristics of Bacterial Nanotubes. Dev Cell 2016; 36:453-61. [DOI: 10.1016/j.devcel.2016.01.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 09/28/2015] [Accepted: 01/22/2016] [Indexed: 01/11/2023]
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Sibling Rivalry in Myxococcus xanthus Is Mediated by Kin Recognition and a Polyploid Prophage. J Bacteriol 2016; 198:994-1004. [PMID: 26787762 DOI: 10.1128/jb.00964-15] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 01/07/2016] [Indexed: 01/24/2023] Open
Abstract
UNLABELLED Myxobacteria form complex social communities that elicit multicellular behaviors. One such behavior is kin recognition, in which cells identify siblings via their polymorphic TraA cell surface receptor, to transiently fuse outer membranes and exchange their contents. In addition, outer membrane exchange (OME) regulates behaviors, such as inhibition of wild-type Myxococcus xanthus (DK1622) from swarming. Here we monitored the fate of motile cells and surprisingly found they were killed by nonmotile siblings. The kill phenotype required OME (i.e., was TraA dependent). The genetic basis of killing was traced to ancestral strains used to construct DK1622. Specifically, the kill phenotype mapped to a large "polyploid prophage," Mx alpha. Sensitive strains contained a 200-kb deletion that removed two of three Mx alpha units. To explain these results, we suggest that Mx alpha expresses a toxin-antitoxin cassette that uses the OME machinery of M. xanthus to transfer a toxin that makes the population "addicted" to Mx alpha. Thus, siblings that lost Mx alpha units (no immunity) are killed by cells that harbor the element. To test this, an Mx alpha-harboring laboratory strain was engineered (by traA allele swap) to recognize a closely related species, Myxococcus fulvus. As a result, M. fulvus, which lacks Mx alpha, was killed. These TraA-mediated antagonisms provide an explanation for how kin recognition specificity might have evolved in myxobacteria. That is, recognition specificity is determined by polymorphisms in traA, which we hypothesize were selected for because OME with non-kin leads to lethal outcomes. IMPORTANCE The transition from single cell to multicellular life is considered a major evolutionary event. Myxobacteria have successfully made this transition. For example, in response to starvation, individual cells aggregate into multicellular fruiting bodies wherein cells differentiate into spores. To build fruits, cells need to recognize their siblings, and in part, this is mediated by the TraA cell surface receptor. Surprisingly, we report that TraA recognition can also involve sibling killing. We show that killing originates from a prophage-like element that has apparently hijacked the TraA system to deliver a toxin to kin. We hypothesize that this killing system has imposed selective pressures on kin recognition, which in turn has resulted in TraA polymorphisms and hence many different recognition groups.
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How Myxobacteria Cooperate. J Mol Biol 2015; 427:3709-21. [PMID: 26254571 DOI: 10.1016/j.jmb.2015.07.022] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Revised: 07/29/2015] [Accepted: 07/30/2015] [Indexed: 11/22/2022]
Abstract
Prokaryotes often reside in groups where a high degree of relatedness has allowed the evolution of cooperative behaviors. However, very few bacteria or archaea have made the successful transition from unicellular to obligate multicellular life. A notable exception is the myxobacteria, in which cells cooperate to perform group functions highlighted by fruiting body development, an obligate multicellular function. Like all multicellular organisms, myxobacteria face challenges in how to organize and maintain multicellularity. These challenges include maintaining population homeostasis, carrying out tissue repair and regulating the behavior of non-cooperators. Here, we describe the major cooperative behaviors that myxobacteria use: motility, predation and development. In addition, this review emphasizes recent discoveries in the social behavior of outer membrane exchange, wherein kin share outer membrane contents. Finally, we review evidence that outer membrane exchange may be involved in regulating population homeostasis, thus serving as a social tool for myxobacteria to make the cyclic transitions from unicellular to multicellular states.
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Jakobczak B, Keilberg D, Wuichet K, Søgaard-Andersen L. Contact- and Protein Transfer-Dependent Stimulation of Assembly of the Gliding Motility Machinery in Myxococcus xanthus. PLoS Genet 2015; 11:e1005341. [PMID: 26132848 PMCID: PMC4488436 DOI: 10.1371/journal.pgen.1005341] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 06/08/2015] [Indexed: 01/06/2023] Open
Abstract
Bacteria engage in contact-dependent activities to coordinate cellular activities that aid their survival. Cells of Myxococcus xanthus move over surfaces by means of type IV pili and gliding motility. Upon direct contact, cells physically exchange outer membrane (OM) lipoproteins, and this transfer can rescue motility in mutants lacking lipoproteins required for motility. The mechanism of gliding motility and its stimulation by transferred OM lipoproteins remain poorly characterized. We investigated the function of CglC, GltB, GltA and GltC, all of which are required for gliding. We demonstrate that CglC is an OM lipoprotein, GltB and GltA are integral OM β-barrel proteins, and GltC is a soluble periplasmic protein. GltB and GltA are mutually stabilizing, and both are required to stabilize GltC, whereas CglC accumulate independently of GltB, GltA and GltC. Consistently, purified GltB, GltA and GltC proteins interact in all pair-wise combinations. Using active fluorescently-tagged fusion proteins, we demonstrate that GltB, GltA and GltC are integral components of the gliding motility complex. Incorporation of GltB and GltA into this complex depends on CglC and GltC as well as on the cytoplasmic AglZ protein and the inner membrane protein AglQ, both of which are components of the gliding motility complex. Conversely, incorporation of AglZ and AglQ into the gliding motility complex depends on CglC, GltB, GltA and GltC. Remarkably, physical transfer of the OM lipoprotein CglC to a ΔcglC recipient stimulates assembly of the gliding motility complex in the recipient likely by facilitating the OM integration of GltB and GltA. These data provide evidence that the gliding motility complex in M. xanthus includes OM proteins and suggest that this complex extends from the cytoplasm across the cell envelope to the OM. These data add assembly of gliding motility complexes in M. xanthus to the growing list of contact-dependent activities in bacteria. Motility facilitates a wide variety of processes such as virulence, biofilm formation and development in bacteria. Bacteria have evolved at least three mechanisms for motility on surfaces: swarming motility, twitching motility and gliding motility. Mechanistically, gliding motility is poorly understood. Here, we focused on four proteins in Myxococcus xanthus that are essential for gliding. We show that CglC is an outer membrane (OM) lipoprotein, GltB and GltA are integral OM β-barrel proteins, and GltC is a soluble periplasmic protein. GltB, GltA and GltC are components of the gliding motility complex, and CglC likely stimulates the integration of GltB and GltA into the OM. Moreover, CglC, in a cell-cell contact-dependent manner, can be transferred from a cglC+ donor to a ΔcglC mutant leading to stimulation of gliding motility in the recipient. We show that upon physical transfer of CglC, CglC stimulates the assembly of the gliding motility complex in the recipient. The data presented here adds to the growing list of cell-cell contact-dependent activities in bacteria by demonstrating that gliding motility can be stimulated in a contact-dependent manner by transfer of a protein that stimulates assembly of the gliding motility complexes.
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Affiliation(s)
- Beata Jakobczak
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Daniela Keilberg
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Kristin Wuichet
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Lotte Søgaard-Andersen
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
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Cell rejuvenation and social behaviors promoted by LPS exchange in myxobacteria. Proc Natl Acad Sci U S A 2015; 112:E2939-46. [PMID: 26038568 DOI: 10.1073/pnas.1503553112] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Bacterial cells in their native environments must cope with factors that compromise the integrity of the cell. The mechanisms of coping with damage in a social or multicellular context are poorly understood. Here we investigated how a model social bacterium, Myxococcus xanthus, approaches this problem. We focused on the social behavior of outer membrane exchange (OME), in which cells transiently fuse and exchange their outer membrane (OM) contents. This behavior requires TraA, a homophilic cell surface receptor that identifies kin based on similarities in a polymorphic region, and the TraB cohort protein. As observed by electron microscopy, TraAB overexpression catalyzed a prefusion OM junction between cells. We then showed that damage sustained by the OM of one population was repaired by OME with a healthy population. Specifically, LPS mutants that were defective in motility and sporulation were rescued by OME with healthy donors. In addition, a mutant with a conditional lethal mutation in lpxC, an essential gene required for lipid A biosynthesis, was rescued by Tra-dependent interactions with a healthy population. Furthermore, lpxC cells with damaged OMs, which were more susceptible to antibiotics, had resistance conferred to them by OME with healthy donors. We also show that OME has beneficial fitness consequences to all cells. Here, in merged populations of damaged and healthy cells, OME catalyzed a dilution of OM damage, increasing developmental sporulation outcomes of the combined population by allowing it to reach a threshold density. We propose that OME is a mechanism that myxobacteria use to overcome cell damage and to transition to a multicellular organism.
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36
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Metabolic cross-feeding via intercellular nanotubes among bacteria. Nat Commun 2015; 6:6238. [PMID: 25703793 DOI: 10.1038/ncomms7238] [Citation(s) in RCA: 166] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 01/08/2015] [Indexed: 12/22/2022] Open
Abstract
Bacteria frequently exchange metabolites by diffusion through the extracellular environment, yet it remains generally unclear whether bacteria can also use cell-cell connections to directly exchange nutrients. Here we address this question by engineering cross-feeding interactions within and between Acinetobacter baylyi and Escherichia coli, in which two distant bacterial species reciprocally exchange essential amino acids. We establish that in a well-mixed environment E. coli, but likely not A. baylyi, can connect to other bacterial cells via membrane-derived nanotubes and use these to exchange cytoplasmic constituents. Intercellular connections are induced by auxotrophy-causing mutations and cease to establish when amino acids are externally supplied. Electron and fluorescence microscopy reveal a network of nanotubular structures that connects bacterial cells and enables an intercellular transfer of cytoplasmic materials. Together, our results demonstrate that bacteria can use nanotubes to exchange nutrients among connected cells and thus help to distribute metabolic functions within microbial communities.
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A genetic screen in Myxococcus xanthus identifies mutants that uncouple outer membrane exchange from a downstream cellular response. J Bacteriol 2014; 196:4324-32. [PMID: 25266387 DOI: 10.1128/jb.02217-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Upon physical contact with sibling cells, myxobacteria transiently fuse their outer membranes (OMs) and exchange OM proteins and lipids. From previous work, TraA and TraB were identified to be essential factors for OM exchange (OME) in donor and recipient cells. To define the genetic complexity of OME, we carried out a comprehensive forward genetic screen. The screen was based on the observation that Myxococcus xanthus nonmotile cells, by a Tra-dependent mechanism, block swarm expansion of motile cells when mixed. Thus, mutants defective in OME or a downstream responsive pathway were readily identified as escape flares from mixed inocula seeded on agar. This screen was surprisingly powerful, as we found >50 mutants defective in OME. Importantly, all of the mutations mapped to the traAB operon, suggesting that there may be few, if any, proteins besides TraA and TraB directly required for OME. We also found a second and phenotypically different class of mutants that exhibited wild-type OME but were defective in a responsive pathway. This pathway is postulated to control inner membrane homeostasis by covalently attaching amino acids to phospholipids. The identified proteins are homologous to the Staphylococcus aureus MprF protein, which is involved in membrane adaptation and antibiotic resistance. Interestingly, we also found that a small number of nonmotile cells were sufficient to block the swarming behavior of a large gliding-proficient population. This result suggests that an OME-derived signal could be amplified from a few nonmotile producers to act on many responder cells.
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Berleman JE, Allen S, Danielewicz MA, Remis JP, Gorur A, Cunha J, Hadi MZ, Zusman DR, Northen TR, Witkowska HE, Auer M. The lethal cargo of Myxococcus xanthus outer membrane vesicles. Front Microbiol 2014; 5:474. [PMID: 25250022 PMCID: PMC4158809 DOI: 10.3389/fmicb.2014.00474] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 08/22/2014] [Indexed: 11/13/2022] Open
Abstract
Myxococcus xanthus is a bacterial micro-predator known for hunting other microbes in a wolf pack-like manner. Outer membrane vesicles (OMVs) are produced in large quantities by M. xanthus and have a highly organized structure in the extracellular milieu, sometimes occurring in chains that link neighboring cells within a biofilm. OMVs may be a vehicle for mediating wolf pack activity by delivering hydrolytic enzymes and antibiotics aimed at killing prey microbes. Here, both the protein and small molecule cargo of the OMV and membrane fractions of M. xanthus were characterized and compared. Our analysis indicates a number of proteins that are OMV-specific or OMV-enriched, including several with putative hydrolytic function. Secondary metabolite profiling of OMVs identifies 16 molecules, many associated with antibiotic activities. Several hydrolytic enzyme homologs were identified, including the protein encoded by MXAN_3564 (mepA), an M36 protease homolog. Genetic disruption of mepA leads to a significant reduction in extracellular protease activity suggesting MepA is part of the long-predicted (yet to date undetermined) extracellular protease suite of M. xanthus.
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Affiliation(s)
- James E Berleman
- Life Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA ; Department of Molecular and Cell Biology, University of California, Berkeley Berkeley, CA, USA ; School of Biology, St. Mary's College Moraga, CA, USA
| | - Simon Allen
- Department of Obstetrics, Gynecology and Reproductive Science, UCSF Sandler-Moore Mass Spectrometry Core Facility San Francisco, CA, USA
| | - Megan A Danielewicz
- Life Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA
| | - Jonathan P Remis
- Life Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA
| | - Amita Gorur
- Life Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA
| | - Jack Cunha
- Life Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA
| | - Masood Z Hadi
- Life Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA ; Space Biosciences Division, Synthetic Biology Program, NASA Ames Research Center Moffett Field, CA, USA ; Physical Biosciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA
| | - David R Zusman
- Department of Molecular and Cell Biology, University of California, Berkeley Berkeley, CA, USA
| | - Trent R Northen
- Life Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA
| | - H Ewa Witkowska
- Department of Obstetrics, Gynecology and Reproductive Science, UCSF Sandler-Moore Mass Spectrometry Core Facility San Francisco, CA, USA
| | - Manfred Auer
- Life Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA
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Abstract
The ability to recognize related cells in a population can confer evolutionary benefits. For example, some bacteria use contact-dependent inhibition proteins to distinguish kin from nonkin. Kinship recognition is taken to a new level in Myxococcus, which uses the dual-purpose TraA protein for kin recognition and outer membrane and lipoprotein exchange. In this issue of the Journal of Bacteriology, Wei et al. (X. Wei, C. N. Vassallo, D. T. Pathak, D. Wall, J. Bacteriol. 196:1807-1814, 2014) show that Tra-dependent exchange can be uncoupled from outer membrane vesicle/tube formation, reported elsewhere to mediate outer membrane exchange.
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