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Tomar P, Thakur N, Jhamta S, Chowdhury S, Kapoor M, Singh S, Shreaz S, Rustagi S, Rai PK, Rai AK, Yadav AN. Bacterial biopesticides: Biodiversity, role in pest management and beneficial impact on agricultural and environmental sustainability. Heliyon 2024; 10:e31550. [PMID: 38828310 PMCID: PMC11140719 DOI: 10.1016/j.heliyon.2024.e31550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 05/15/2024] [Accepted: 05/17/2024] [Indexed: 06/05/2024] Open
Abstract
Agro-environmental sustainability is based upon the adoption of efficient resources in agro-practices that have a nominal impact on the ecosystem. Insect pests are responsible for causing severe impacts on crop productivity. Wide ranges of agro-chemicals have been employed over the last 50 years to overcome crop yield losses due to insect pests. But better knowledge about the hazards due to chemical pesticides and other pest resistance and resurgence issues necessitates an alternative for pest control. The applications of biological pesticides offer a best alternate that is safe, cost-effective, easy to adoption and successful against various insect pests and pathogens. Like other organisms, insects can get a wide range of diseases from various microbes, such as bacteria, fungi, viruses, protozoa, and nematodes. In order to create agricultural pest management practices that are environmentally beneficial, bacterial entomopathogens are being thoroughly studied. Utilization of bacterial biopesticides has been adopted for the protection of agricultural products. The different types of toxin complexes released by various microorganisms and their mechanisms of action are recapitulated. The present review described the diversity and biocontrol prospective of certain bacteria and summarised the potential of bacterial biopesticides for the management of agricultural pests, insects, and other phytopathogenic microorganisms in agricultural practices.
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Affiliation(s)
- Preety Tomar
- Department of Zoology, Akal College of Basic Sciences, Eternal University, Sirmour, Himachal Pradesh, India
| | - Neelam Thakur
- Department of Zoology, Akal College of Basic Sciences, Eternal University, Sirmour, Himachal Pradesh, India
| | - Samiksha Jhamta
- Department of Zoology, Akal College of Basic Sciences, Eternal University, Sirmour, Himachal Pradesh, India
| | - Sohini Chowdhury
- Chitkara Center for Research and Development, Chitkara University, Himachal Pradesh, India
| | - Monit Kapoor
- Centre of Research Impact and Outcome, Chitkara University, Rajpura, 140401, Punjab, India
| | - Sangram Singh
- Department of Biochemistry, Dr. Ram Manohar Lohia Avadh University Faizabad, Uttar Pradesh, India
| | - Sheikh Shreaz
- Desert Agriculture and Ecosystems Program, Environment and Life Sciences Research Center, Kuwait Institute for Scientific Research, PO Box 24885, 13109, Safat, Kuwait
| | - Sarvesh Rustagi
- Department of Food Technology, School of Applied and Life Sciences, Uttaranchal University, Dehradun, Uttarakhand, India
| | - Pankaj Kumar Rai
- Department of Biotechnology, Invertis University, Bareilly, Uttar Pradesh, India
| | - Ashutosh Kumar Rai
- Department of Biochemistry, College of Medicine, Imam Abdulrahman Bin Faisal University, Dammam, Kingdom of Saudi Arabia
| | - Ajar Nath Yadav
- Department of Genetics, Plant Breeding and Biotechnology, Dr. Khem Singh Gill Akal College of Agriculture, Eternal University, Baru Sahib, Sirmour, Himachal Pradesh, India
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Busby JN, Trevelyan S, Pegg CL, Kerr ED, Schulz BL, Chassagnon I, Landsberg MJ, Weston MK, Hurst MRH, Lott JS. The ABC toxin complex from Yersinia entomophaga can package three different cytotoxic components expressed from distinct genetic loci in an unfolded state: the structures of both shell and cargo. IUCRJ 2024; 11:299-308. [PMID: 38512773 PMCID: PMC11067744 DOI: 10.1107/s2052252524001969] [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: 01/24/2023] [Accepted: 02/28/2024] [Indexed: 03/23/2024]
Abstract
Bacterial ABC toxin complexes (Tcs) comprise three core proteins: TcA, TcB and TcC. The TcA protein forms a pentameric assembly that attaches to the surface of target cells and penetrates the cell membrane. The TcB and TcC proteins assemble as a heterodimeric TcB-TcC subcomplex that makes a hollow shell. This TcB-TcC subcomplex self-cleaves and encapsulates within the shell a cytotoxic `cargo' encoded by the C-terminal region of the TcC protein. Here, we describe the structure of a previously uncharacterized TcC protein from Yersinia entomophaga, encoded by a gene at a distant genomic location from the genes encoding the rest of the toxin complex, in complex with the TcB protein. When encapsulated within the TcB-TcC shell, the C-terminal toxin adopts an unfolded and disordered state, with limited areas of local order stabilized by the chaperone-like inner surface of the shell. We also determined the structure of the toxin cargo alone and show that when not encapsulated within the shell, it adopts an ADP-ribosyltransferase fold most similar to the catalytic domain of the SpvB toxin from Salmonella typhimurium. Our structural analysis points to a likely mechanism whereby the toxin acts directly on actin, modifying it in a way that prevents normal polymerization.
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Affiliation(s)
- Jason N. Busby
- School of Biological Sciences, University of Auckland, Auckland 1142, New Zealand
| | - Sarah Trevelyan
- School of Biological Sciences, University of Auckland, Auckland 1142, New Zealand
| | - Cassandra L. Pegg
- School of Chemistry and Molecular Biosciences, University of Central Queensland, Brisbane, Queensland 4072, Australia
| | - Edward D. Kerr
- School of Chemistry and Molecular Biosciences, University of Central Queensland, Brisbane, Queensland 4072, Australia
| | - Benjamin L. Schulz
- School of Chemistry and Molecular Biosciences, University of Central Queensland, Brisbane, Queensland 4072, Australia
| | - Irene Chassagnon
- School of Chemistry and Molecular Biosciences, University of Central Queensland, Brisbane, Queensland 4072, Australia
| | - Michael J. Landsberg
- School of Chemistry and Molecular Biosciences, University of Central Queensland, Brisbane, Queensland 4072, Australia
| | - Mitchell K. Weston
- Resilient Agriculture, AgResearch, Lincoln Research Centre, Christchurch 8140, New Zealand
| | - Mark R. H. Hurst
- Resilient Agriculture, AgResearch, Lincoln Research Centre, Christchurch 8140, New Zealand
| | - J. Shaun Lott
- School of Biological Sciences, University of Auckland, Auckland 1142, New Zealand
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Schmidt G. Some Examples of Bacterial Toxins as Tools. Toxins (Basel) 2024; 16:202. [PMID: 38787054 PMCID: PMC11125981 DOI: 10.3390/toxins16050202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 04/18/2024] [Accepted: 04/20/2024] [Indexed: 05/25/2024] Open
Abstract
Pathogenic bacteria produce diverse protein toxins to disturb the host's defenses. This includes the opening of epithelial barriers to establish bacterial growth in deeper tissues of the host and to modulate immune cell functions. To achieve this, many toxins share the ability to enter mammalian cells, where they catalyze the modification of cellular proteins. The enzymatic activity is diverse and ranges from ribosyl- or glycosyl-transferase activity, the deamidation of proteins, and adenylate-cyclase activity to proteolytic cleavage. Protein toxins are highly active enzymes often with tight specificity for an intracellular protein or a protein family coupled with the intrinsic capability of entering mammalian cells. A broad understanding of their molecular mechanisms established bacterial toxins as powerful tools for cell biology. Both the enzymatic part and the pore-forming/protein transport capacity are currently used as tools engineered to study signaling pathways or to transport cargo like labeled compounds, nucleic acids, peptides, or proteins directly into the cytosol. Using several representative examples, this review is intended to provide a short overview of the state of the art in the use of bacterial toxins or parts thereof as tools.
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Affiliation(s)
- Gudula Schmidt
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Albertstr. 25, 79104 Freiburg, Germany
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4
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Krantz BA. Anthrax Toxin: Model System for Studying Protein Translocation. J Mol Biol 2024; 436:168521. [PMID: 38458604 DOI: 10.1016/j.jmb.2024.168521] [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: 11/17/2023] [Revised: 02/08/2024] [Accepted: 03/04/2024] [Indexed: 03/10/2024]
Abstract
Dedicated translocase channels are nanomachines that often, but not always, unfold and translocate proteins through narrow pores across the membrane. Generally, these molecular machines utilize external sources of free energy to drive these reactions, since folded proteins are thermodynamically stable, and once unfolded they contain immense diffusive configurational entropy. To catalyze unfolding and translocate the unfolded state at appreciable timescales, translocase channels often utilize analogous peptide-clamp active sites. Here we describe how anthrax toxin has been used as a biophysical model system to study protein translocation. The tripartite bacterial toxin is composed of an oligomeric translocase channel, protective antigen (PA), and two enzymes, edema factor (EF) and lethal factor (LF), which are translocated by PA into mammalian host cells. Unfolding and translocation are powered by the endosomal proton gradient and are catalyzed by three peptide-clamp sites in the PA channel: the α clamp, the ϕ clamp, and the charge clamp. These clamp sites interact nonspecifically with the chemically complex translocating chain, serve to minimize unfolded state configurational entropy, and work cooperatively to promote translocation. Two models of proton gradient driven translocation have been proposed: (i) an extended-chain Brownian ratchet mechanism and (ii) a proton-driven helix-compression mechanism. These models are not mutually exclusive; instead the extended-chain Brownian ratchet likely operates on β-sheet sequences and the helix-compression mechanism likely operates on α-helical sequences. Finally, we compare and contrast anthrax toxin with other related and unrelated translocase channels.
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Affiliation(s)
- Bryan A Krantz
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, 650 W. Baltimore Street, Baltimore, MD 21201, USA.
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Williams TJ, Allen MA, Ray AE, Benaud N, Chelliah DS, Albanese D, Donati C, Selbmann L, Coleine C, Ferrari BC. Novel endolithic bacteria of phylum Chloroflexota reveal a myriad of potential survival strategies in the Antarctic desert. Appl Environ Microbiol 2024; 90:e0226423. [PMID: 38372512 PMCID: PMC10952385 DOI: 10.1128/aem.02264-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 01/02/2024] [Indexed: 02/20/2024] Open
Abstract
The ice-free McMurdo Dry Valleys of Antarctica are dominated by nutrient-poor mineral soil and rocky outcrops. The principal habitat for microorganisms is within rocks (endolithic). In this environment, microorganisms are provided with protection against sub-zero temperatures, rapid thermal fluctuations, extreme dryness, and ultraviolet and solar radiation. Endolithic communities include lichen, algae, fungi, and a diverse array of bacteria. Chloroflexota is among the most abundant bacterial phyla present in these communities. Among the Chloroflexota are four novel classes of bacteria, here named Candidatus Spiritibacteria class. nov. (=UBA5177), Candidatus Martimicrobia class. nov. (=UBA4733), Candidatus Tarhunnaeia class. nov. (=UBA6077), and Candidatus Uliximicrobia class. nov. (=UBA2235). We retrieved 17 high-quality metagenome-assembled genomes (MAGs) that represent these four classes. Based on genome predictions, all these bacteria are inferred to be aerobic heterotrophs that encode enzymes for the catabolism of diverse sugars. These and other organic substrates are likely derived from lichen, algae, and fungi, as metabolites (including photosynthate), cell wall components, and extracellular matrix components. The majority of MAGs encode the capacity for trace gas oxidation using high-affinity uptake hydrogenases, which could provide energy and metabolic water required for survival and persistence. Furthermore, some MAGs encode the capacity to couple the energy generated from H2 and CO oxidation to support carbon fixation (atmospheric chemosynthesis). All encode mechanisms for the detoxification and efflux of heavy metals. Certain MAGs encode features that indicate possible interactions with other organisms, such as Tc-type toxin complexes, hemolysins, and macroglobulins.IMPORTANCEThe ice-free McMurdo Dry Valleys of Antarctica are the coldest and most hyperarid desert on Earth. It is, therefore, the closest analog to the surface of the planet Mars. Bacteria and other microorganisms survive by inhabiting airspaces within rocks (endolithic). We identify four novel classes of phylum Chloroflexota, and, based on interrogation of 17 metagenome-assembled genomes, we predict specific metabolic and physiological adaptations that facilitate the survival of these bacteria in this harsh environment-including oxidation of trace gases and the utilization of nutrients (including sugars) derived from lichen, algae, and fungi. We propose that such adaptations allow these endolithic bacteria to eke out an existence in this cold and extremely dry habitat.
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Affiliation(s)
- Timothy J. Williams
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Michelle A. Allen
- School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Angelique E. Ray
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Nicole Benaud
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Devan S. Chelliah
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Davide Albanese
- Research and Innovation Center, Fondazione Edmund Mach, San Michele all’Adige, Italy
| | - Claudio Donati
- Research and Innovation Center, Fondazione Edmund Mach, San Michele all’Adige, Italy
| | - Laura Selbmann
- Department of Ecological and Biological Sciences, University of Tuscia, Largo dell’Università, Viterbo, Italy
- Mycological Section, Italian Antarctic National Museum (MNA), Genova, Italy
| | - Claudia Coleine
- Department of Ecological and Biological Sciences, University of Tuscia, Largo dell’Università, Viterbo, Italy
| | - Belinda C. Ferrari
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales, Australia
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6
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Feldmüller M, Ericson CF, Afanasyev P, Lien YW, Weiss GL, Wollweber F, Schoof M, Hurst M, Pilhofer M. Stepwise assembly and release of Tc toxins from Yersinia entomophaga. Nat Microbiol 2024; 9:405-420. [PMID: 38316932 PMCID: PMC10847046 DOI: 10.1038/s41564-024-01611-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 01/17/2024] [Indexed: 02/07/2024]
Abstract
Tc toxins are virulence factors of bacterial pathogens. Although their structure and intoxication mechanism are well understood, it remains elusive where this large macromolecular complex is assembled and how it is released. Here we show by an integrative multiscale imaging approach that Yersinia entomophaga Tc (YenTc) toxin components are expressed only in a subpopulation of cells that are 'primed' with several other potential virulence factors, including filaments of the protease M66/StcE. A phage-like lysis cassette is required for YenTc release; however, before resulting in complete cell lysis, the lysis cassette generates intermediate 'ghost' cells, which may serve as assembly compartments and become packed with assembled YenTc holotoxins. We hypothesize that this stepwise mechanism evolved to minimize the number of cells that need to be killed. The occurrence of similar lysis cassettes in diverse organisms indicates a conserved mechanism for Tc toxin release that may apply to other extracellular macromolecular machines.
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Affiliation(s)
- Miki Feldmüller
- Department of Biology, Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | - Charles F Ericson
- Department of Biology, Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | | | - Yun-Wei Lien
- Department of Biology, Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | - Gregor L Weiss
- Department of Biology, Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | - Florian Wollweber
- Department of Biology, Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | - Marion Schoof
- Bio-Protection Research Centre, Lincoln University, Lincoln, Christchurch, New Zealand
- AgResearch, Resilient Agriculture, Lincoln Research Centre, Christchurch, New Zealand
| | - Mark Hurst
- Bio-Protection Research Centre, Lincoln University, Lincoln, Christchurch, New Zealand
- AgResearch, Resilient Agriculture, Lincoln Research Centre, Christchurch, New Zealand
| | - Martin Pilhofer
- Department of Biology, Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland.
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7
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Sitsel O, Wang Z, Janning P, Kroczek L, Wagner T, Raunser S. Yersinia entomophaga Tc toxin is released by T10SS-dependent lysis of specialized cell subpopulations. Nat Microbiol 2024; 9:390-404. [PMID: 38238469 PMCID: PMC10847048 DOI: 10.1038/s41564-023-01571-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 11/29/2023] [Indexed: 02/04/2024]
Abstract
Disease-causing bacteria secrete numerous toxins to invade and subjugate their hosts. Unlike many smaller toxins, the secretion machinery of most large toxins remains enigmatic. By combining genomic editing, proteomic profiling and cryo-electron tomography of the insect pathogen Yersinia entomophaga, we demonstrate that a specialized subset of these cells produces a complex toxin cocktail, including the nearly ribosome-sized Tc toxin YenTc, which is subsequently exported by controlled cell lysis using a transcriptionally coupled, pH-dependent type 10 secretion system (T10SS). Our results dissect the Tc toxin export process by a T10SS, identifying that T10SSs operate via a previously unknown lytic mode of action and establishing them as crucial players in the size-insensitive release of cytoplasmically folded toxins. With T10SSs directly embedded in Tc toxin operons of major pathogens, we anticipate that our findings may model an important aspect of pathogenesis in bacteria with substantial impact on agriculture and healthcare.
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Affiliation(s)
- Oleg Sitsel
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Zhexin Wang
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Petra Janning
- Department of Chemical Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Lara Kroczek
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Thorsten Wagner
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
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8
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Belyy A, Heilen P, Hagel P, Hofnagel O, Raunser S. Structure and activation mechanism of the Makes caterpillars floppy 1 toxin. Nat Commun 2023; 14:8226. [PMID: 38086871 PMCID: PMC10716152 DOI: 10.1038/s41467-023-44069-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 11/29/2023] [Indexed: 12/18/2023] Open
Abstract
The bacterial Makes caterpillars floppy 1 (Mcf1) toxin promotes apoptosis in insects, leading to loss of body turgor and death. The molecular mechanism underlying Mcf1 intoxication is poorly understood. Here, we present the cryo-EM structure of Mcf1 from Photorhabdus luminescens, revealing a seahorse-like shape with a head and tail. While the three head domains contain two effectors, as well as an activator-binding domain (ABD) and an autoprotease, the tail consists of two putative translocation and three putative receptor-binding domains. Rearrangement of the tail moves the C-terminus away from the ABD and allows binding of the host cell ADP-ribosylation factor 3, inducing conformational changes that position the cleavage site closer to the protease. This distinct activation mechanism that is based on a hook-loop interaction results in three autocleavage reactions and the release of two toxic effectors. Unexpectedly, the BH3-like domain containing ABD is not an active effector. Our findings allow us to understand key steps of Mcf1 intoxication at the molecular level.
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Affiliation(s)
- Alexander Belyy
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Philipp Heilen
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Philine Hagel
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Oliver Hofnagel
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany.
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9
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Martin CL, Chester DW, Radka CD, Pan L, Yang Z, Hart RC, Binshtein EM, Wang Z, Nagy L, DeLucas LJ, Aller SG. Structures of the Insecticidal Toxin Complex Subunit XptA2 Highlight Roles for Flexible Domains. Int J Mol Sci 2023; 24:13221. [PMID: 37686027 PMCID: PMC10487846 DOI: 10.3390/ijms241713221] [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: 07/31/2023] [Revised: 08/18/2023] [Accepted: 08/20/2023] [Indexed: 09/10/2023] Open
Abstract
The Toxin Complex (Tc) superfamily consists of toxin translocases that contribute to the targeting, delivery, and cytotoxicity of certain pathogenic Gram-negative bacteria. Membrane receptor targeting is driven by the A-subunit (TcA), which comprises IgG-like receptor binding domains (RBDs) at the surface. To better understand XptA2, an insect specific TcA secreted by the symbiont X. nematophilus from the intestine of entomopathogenic nematodes, we determined structures by X-ray crystallography and cryo-EM. Contrary to a previous report, XptA2 is pentameric. RBD-B exhibits an indentation from crystal packing that indicates loose association with the shell and a hotspot for possible receptor binding or a trigger for conformational dynamics. A two-fragment XptA2 lacking an intact linker achieved the folded pre-pore state like wild type (wt), revealing no requirement of the linker for protein folding. The linker is disordered in all structures, and we propose it plays a role in dynamics downstream of the initial pre-pore state.
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Affiliation(s)
- Cole L. Martin
- Department of Pharmacology & Toxicology, University of Alabama at Birmingham, Birmingham, AL 35205, USA; (C.L.M.); (D.W.C.); (C.D.R.); (L.P.)
| | - David W. Chester
- Department of Pharmacology & Toxicology, University of Alabama at Birmingham, Birmingham, AL 35205, USA; (C.L.M.); (D.W.C.); (C.D.R.); (L.P.)
| | - Christopher D. Radka
- Department of Pharmacology & Toxicology, University of Alabama at Birmingham, Birmingham, AL 35205, USA; (C.L.M.); (D.W.C.); (C.D.R.); (L.P.)
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, KY 40536, USA
| | - Lurong Pan
- Department of Pharmacology & Toxicology, University of Alabama at Birmingham, Birmingham, AL 35205, USA; (C.L.M.); (D.W.C.); (C.D.R.); (L.P.)
| | - Zhengrong Yang
- Department of Biochemistry & Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35205, USA;
| | - Rachel C. Hart
- Department of Pathology, Microbiology & Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (R.C.H.); (E.M.B.)
| | - Elad M. Binshtein
- Department of Pathology, Microbiology & Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (R.C.H.); (E.M.B.)
| | - Zhao Wang
- Biochemistry & Molecular Pharmacology, Cryo-Electron Microscopy and Tomography Core, Baylor College of Medicine, Houston, TX 77030, USA;
| | - Lisa Nagy
- Department of Mathematics, Engineering & Physical Sciences, Jefferson State Community College, Jefferson Campus, Birmingham, AL 35215, USA;
| | - Lawrence J. DeLucas
- Predictive Oncology Inc., 200 Riverhills Business Park, Suite 250, Birmingham, AL 35242, USA;
| | - Stephen G. Aller
- Department of Pharmacology & Toxicology, University of Alabama at Birmingham, Birmingham, AL 35205, USA; (C.L.M.); (D.W.C.); (C.D.R.); (L.P.)
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Sänger PA, Knüpfer M, Kegel M, Spanier B, Liebler-Tenorio EM, Fuchs TM. Regulation and Functionality of a Holin/Endolysin Pair Involved in Killing of Galleria mellonella and Caenorhabditis elegans by Yersinia enterocolitica. Appl Environ Microbiol 2023; 89:e0003623. [PMID: 37184385 PMCID: PMC10304863 DOI: 10.1128/aem.00036-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 03/30/2023] [Indexed: 05/16/2023] Open
Abstract
The insecticidal toxin complex (Tc) proteins are produced by several insect-associated bacteria, including Yersinia enterocolitica strain W22703, which oscillates between two distinct pathogenicity phases in invertebrates and humans. The mechanism by which this high-molecular-weight toxin is released into the extracellular surrounding, however, has not been deciphered. In this study, we investigated the regulation and functionality of a phage-related holin/endolysin (HE) cassette located within the insecticidal pathogenicity island Tc-PAIYe of W22703. Using the Galleria mellonella infection model and luciferase reporter fusions, we revealed that quorum sensing contributes to the insecticidal activity of W22703 upon influencing the transcription of tcaR2, which encodes an activator of the tc and HE genes. In contrast, a lack of the Yersinia modulator, YmoA, stimulated HE gene transcription, and mutant W22703 ΔymoA exhibited a stronger toxicity toward insect larvae than did W22703. A luciferase reporter fusion demonstrated transcriptional activation of the HE cassette in vivo, and a significantly larger extracellular amount of subunit TcaA was found in W22703 ΔymoA relative to its ΔHE mutant. Using competitive growth assays, we demonstrated that at least in vitro, the TcaA release upon HE activity is not mediated by cell lysis of a significant part of the population. Oral infection of Caenorhabditis elegans with a HE deletion mutant attenuated the nematocidal activity of the wild type, similar to the case with a mutant lacking a Tc subunit. We conclude that the dual holin/endolysin cassette of yersiniae is a novel example of a phage-related function adapted for the release of a bacterial toxin. IMPORTANCE Members of the genus Yersinia cause gastroenteritis in humans but also exhibit toxicity toward invertebrates. A virulence factor required for this environmental life cycle stage is the multisubunit toxin complex (Tc), which is distinct from the insecticidal toxin of Bacillus thuringiensis and has the potential to be used in pest control. The mechanism by which this high-molecular-weight Tc is secreted from bacterial cells has not been uncovered. Here, we show that a highly conserved phage-related holin/endolysin pair, which is encoded by the genes holY and elyY located between the Tc subunit genes, is essential for the insecticidal activity of Y. enterocolitica and that its activation increases the amount of Tc subunits in the supernatant. Thus, the dual holY-elyY cassette of Y. enterocolitica constitutes a new example for a type 10 secretion system to release bacterial toxins.
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Affiliation(s)
| | - Mandy Knüpfer
- Chair for Microbial Ecology, Institute for Food and Health (ZIEL), TUM School of Life Sciences, Technische Universität München, Freising, Germany
| | - Marcel Kegel
- Chair for Microbial Ecology, Institute for Food and Health (ZIEL), TUM School of Life Sciences, Technische Universität München, Freising, Germany
| | - Britta Spanier
- Chair for Metabolic Programming, Institute for Food and Health (ZIEL), TUM School of Life Sciences, Technische Universität München, Freising, Germany
| | | | - Thilo M. Fuchs
- Friedrich-Loeffler-Institut, Institute of Molecular Pathogenesis, Jena, Germany
- Chair for Microbial Ecology, Institute for Food and Health (ZIEL), TUM School of Life Sciences, Technische Universität München, Freising, Germany
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11
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Pacheco S, Gómez I, Peláez-Aguilar AE, Verduzco-Rosas LA, García-Suárez R, do Nascimento NA, Rivera-Nájera LY, Cantón PE, Soberón M, Bravo A. Structural changes upon membrane insertion of the insecticidal pore-forming toxins produced by Bacillus thuringiensis. FRONTIERS IN INSECT SCIENCE 2023; 3:1188891. [PMID: 38469496 PMCID: PMC10926538 DOI: 10.3389/finsc.2023.1188891] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Accepted: 04/04/2023] [Indexed: 03/13/2024]
Abstract
Different Bacillus thuringiensis (Bt) strains produce a broad variety of pore-forming toxins (PFTs) that show toxicity against insects and other invertebrates. Some of these insecticidal PFT proteins have been used successfully worldwide to control diverse insect crop pests. There are several studies focused on describing the mechanism of action of these toxins that have helped to improve their performance and to cope with the resistance evolved by different insects against some of these proteins. However, crucial information that is still missing is the structure of pores formed by some of these PFTs, such as the three-domain crystal (Cry) proteins, which are the most commercially used Bt toxins in the biological control of insect pests. In recent years, progress has been made on the identification of the structural changes that certain Bt insecticidal PFT proteins undergo upon membrane insertion. In this review, we describe the models that have been proposed for the membrane insertion of Cry toxins. We also review the recently published structures of the vegetative insecticidal proteins (Vips; e.g. Vip3) and the insecticidal toxin complex (Tc) in the membrane-inserted state. Although different Bt PFTs show different primary sequences, there are some similarities in the three-dimensional structures of Vips and Cry proteins. In addition, all PFTs described here must undergo major structural rearrangements to pass from a soluble form to a membrane-inserted state. It is proposed that, despite their structural differences, all PFTs undergo major structural rearrangements producing an extended α-helix, which plays a fundamental role in perforating their target membrane, resulting in the formation of the membrane pore required for their insecticidal activity.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Alejandra Bravo
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
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12
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Native structure of mosquito salivary protein uncovers domains relevant to pathogen transmission. Nat Commun 2023; 14:899. [PMID: 36797290 PMCID: PMC9935623 DOI: 10.1038/s41467-023-36577-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 02/07/2023] [Indexed: 02/18/2023] Open
Abstract
Female mosquitoes inject saliva into vertebrate hosts during blood feeding. This process transmits mosquito-borne human pathogens that collectively cause ~1,000,000 deaths/year. Among the most abundant and conserved proteins secreted by female salivary glands is a high-molecular weight protein called salivary gland surface protein 1 (SGS1) that facilitates pathogen transmission, but its mechanism remains elusive. Here, we determine the native structure of SGS1 by the cryoID approach, showing that the 3364 amino-acid protein has a Tc toxin-like Rhs/YD shell, four receptor domains, and a set of C-terminal daisy-chained helices. These helices are partially shielded inside the Rhs/YD shell and poised to transform into predicted transmembrane helices. This transformation, and the numerous receptor domains on the surface of SGS1, are likely key in facilitating sporozoite/arbovirus invasion into the salivary glands and manipulating the host's immune response.
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13
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Sänger PA, Wagner S, Liebler-Tenorio EM, Fuchs TM. Dissecting the invasion of Galleria mellonella by Yersinia enterocolitica reveals metabolic adaptations and a role of a phage lysis cassette in insect killing. PLoS Pathog 2022; 18:e1010991. [PMID: 36399504 PMCID: PMC9718411 DOI: 10.1371/journal.ppat.1010991] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 12/02/2022] [Accepted: 11/08/2022] [Indexed: 11/19/2022] Open
Abstract
The human pathogen Yersinia enterocolitica strain W22703 is characterized by its toxicity towards invertebrates that requires the insecticidal toxin complex (Tc) proteins encoded by the pathogenicity island Tc-PAIYe. Molecular and pathophysiological details of insect larvae infection and killing by this pathogen, however, have not been dissected. Here, we applied oral infection of Galleria mellonella (Greater wax moth) larvae to study the colonisation, proliferation, tissue invasion, and killing activity of W22703. We demonstrated that this strain is strongly toxic towards the larvae, in which they proliferate by more than three orders of magnitude within six days post infection. Deletion mutants of the genes tcaA and tccC were atoxic for the insect. W22703 ΔtccC, in contrast to W22703 ΔtcaA, initially proliferated before being eliminated from the host, thus confirming TcaA as membrane-binding Tc subunit and TccC as cell toxin. Time course experiments revealed a Tc-dependent infection process starting with midgut colonisation that is followed by invasion of the hemolymph where the pathogen elicits morphological changes of hemocytes and strongly proliferates. The in vivo transcriptome of strain W22703 shows that the pathogen undergoes a drastic reprogramming of central cell functions and gains access to numerous carbohydrate and amino acid resources within the insect. Strikingly, a mutant lacking a phage-related holin/endolysin (HE) cassette, which is located within Tc-PAIYe, resembled the phenotypes of W22703 ΔtcaA, suggesting that this dual lysis cassette may be an example of a phage-related function that has been adapted for the release of a bacterial toxin.
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Affiliation(s)
| | - Stefanie Wagner
- Friedrich-Loeffler-Institut, Institut für Molekulare Pathogenese, Jena, Germany
| | | | - Thilo M. Fuchs
- Friedrich-Loeffler-Institut, Institut für Molekulare Pathogenese, Jena, Germany
- * E-mail:
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14
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Jia X, Knyazeva A, Zhang Y, Castro-Gonzalez S, Nakamura S, Carlson LA, Yoshimori T, Corkery DP, Wu YW. V. cholerae MakA is a cholesterol-binding pore-forming toxin that induces non-canonical autophagy. J Cell Biol 2022; 221:213518. [PMID: 36194176 PMCID: PMC9536202 DOI: 10.1083/jcb.202206040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 08/16/2022] [Accepted: 09/16/2022] [Indexed: 01/18/2023] Open
Abstract
Pore-forming toxins (PFTs) are important virulence factors produced by many pathogenic bacteria. Here, we show that the Vibrio cholerae toxin MakA is a novel cholesterol-binding PFT that induces non-canonical autophagy in a pH-dependent manner. MakA specifically binds to cholesterol on the membrane at pH < 7. Cholesterol-binding leads to oligomerization of MakA on the membrane and pore formation at pH 5.5. Unlike other cholesterol-dependent cytolysins (CDCs) which bind cholesterol through a conserved cholesterol-binding motif (Thr-Leu pair), MakA contains an Ile-Ile pair that is essential for MakA-cholesterol interaction. Following internalization, endosomal acidification triggers MakA pore-assembly followed by ESCRT-mediated membrane repair and V-ATPase-dependent unconventional LC3 lipidation on the damaged endolysosomal membranes. These findings characterize a new cholesterol-binding toxin that forms pores in a pH-dependent manner and reveals the molecular mechanism of host autophagy manipulation.
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Affiliation(s)
- Xiaotong Jia
- Department of Chemistry, Umeå University, Umeå, Sweden,Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Anastasia Knyazeva
- Department of Chemistry, Umeå University, Umeå, Sweden,Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Yu Zhang
- Department of Chemistry, Umeå University, Umeå, Sweden,Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Sergio Castro-Gonzalez
- Department of Chemistry, Umeå University, Umeå, Sweden,Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Shuhei Nakamura
- Department of Genetics, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Lars-Anders Carlson
- Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden,Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden,Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden,Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
| | - Tamotsu Yoshimori
- Department of Genetics, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Dale P. Corkery
- Department of Chemistry, Umeå University, Umeå, Sweden,Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden,Dale P. Corkery:
| | - Yao-Wen Wu
- Department of Chemistry, Umeå University, Umeå, Sweden,Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden,Correspondence to Yao-Wen Wu:
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15
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CRISPR screens in Drosophila cells identify Vsg as a Tc toxin receptor. Nature 2022; 610:349-355. [PMID: 36171290 PMCID: PMC9631961 DOI: 10.1038/s41586-022-05250-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 08/18/2022] [Indexed: 11/08/2022]
Abstract
Entomopathogenic nematodes are widely used as biopesticides1,2. Their insecticidal activity depends on symbiotic bacteria such as Photorhabdus luminescens, which produces toxin complex (Tc) toxins as major virulence factors3-6. No protein receptors are known for any Tc toxins, which limits our understanding of their specificity and pathogenesis. Here we use genome-wide CRISPR-Cas9-mediated knockout screening in Drosophila melanogaster S2R+ cells and identify Visgun (Vsg) as a receptor for an archetypal P. luminescens Tc toxin (pTc). The toxin recognizes the extracellular O-glycosylated mucin-like domain of Vsg that contains high-density repeats of proline, threonine and serine (HD-PTS). Vsg orthologues in mosquitoes and beetles contain HD-PTS and can function as pTc receptors, whereas orthologues without HD-PTS, such as moth and human versions, are not pTc receptors. Vsg is expressed in immune cells, including haemocytes and fat body cells. Haemocytes from Vsg knockout Drosophila are resistant to pTc and maintain phagocytosis in the presence of pTc, and their sensitivity to pTc is restored through the transgenic expression of mosquito Vsg. Last, Vsg knockout Drosophila show reduced bacterial loads and lethality from P. luminescens infection. Our findings identify a proteinaceous Tc toxin receptor, reveal how Tc toxins contribute to P. luminescens pathogenesis, and establish a genome-wide CRISPR screening approach for investigating insecticidal toxins and pathogens.
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16
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Liu J, Bai H, Song P, Nangong Z, Dong Z, Li Z, Wang Q. Insecticidal Activity of Chitinases from Xenorhabdus nematophila HB310 and Its Relationship with the Toxin Complex. Toxins (Basel) 2022; 14:toxins14090646. [PMID: 36136584 PMCID: PMC9505380 DOI: 10.3390/toxins14090646] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/07/2022] [Accepted: 09/15/2022] [Indexed: 11/18/2022] Open
Abstract
Xenorhabdus nematophila HB310 secreted the insecticidal protein toxin complex (Tc). The chi60 and chi70 chitinase genes are located on the gene cluster encoding Tc toxins. To clarify the insecticidal activity of chitinases and their relationship with Tc toxins, the insecticidal activity of the chitinases was assessed on Helicoverpa armigera. Then, the chi60 and chi70 genes of X. nematophila HB310 were knocked out by the pJQ200SK suicide plasmid knockout system. The insecticidal activity of Tc toxin from the wild-type strain (WT) and mutant strains was carried out. The results demonstrate that Chi60 and Chi70 had an obvious growth inhibition effect against the second instar larvae of H. armigera with growth-inhibiting rates of 81.99% and 90.51%, respectively. Chi70 had a synergistic effect with the insecticidal toxicity of Tc toxins, but Chi60 had no synergistic effect with Tc toxins. After feeding Chi60 and Chi70, the peritrophic membrane of H. armigera became inelastic, was easily broken and leaked blue dextran. The Δchi60, Δchi70 and Δchi60-chi70 mutant strains were successfully screened. The toxicity of Tc toxins from the WT, Δchi60, Δchi70 and Δchi60-chi70 was 196.11 μg/mL, 757.25 μg/mL, 885.74 μg/mL and 20,049.83 μg/mL, respectively. The insecticidal activity of Tc toxins from Δchi60 and Δchi70 was 3.861 and 4.517 times lower than that of Tc toxins from the WT, respectively, while the insecticidal activity of Tc toxins from the Δchi60-chi70 mutant strain almost disappeared. These results indicate that the presence of chi60 and chi70 is indispensable for the toxicity of Tc toxins.
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Affiliation(s)
- Jia Liu
- Institute of Millet Crops, Hebei Academy of Agriculture and Forestry Sciences, National Foxtail Millet Improvement Center, Minor Cereal Crops Laboratory of Hebei Province, Shijiazhuang 050035, China
| | - Hui Bai
- Institute of Millet Crops, Hebei Academy of Agriculture and Forestry Sciences, National Foxtail Millet Improvement Center, Minor Cereal Crops Laboratory of Hebei Province, Shijiazhuang 050035, China
| | - Ping Song
- College of Plant Protection, Hebei Agricultural University, Baoding 071000, China
| | - Ziyan Nangong
- College of Plant Protection, Hebei Agricultural University, Baoding 071000, China
| | - Zhiping Dong
- Institute of Millet Crops, Hebei Academy of Agriculture and Forestry Sciences, National Foxtail Millet Improvement Center, Minor Cereal Crops Laboratory of Hebei Province, Shijiazhuang 050035, China
| | - Zhiyong Li
- Institute of Millet Crops, Hebei Academy of Agriculture and Forestry Sciences, National Foxtail Millet Improvement Center, Minor Cereal Crops Laboratory of Hebei Province, Shijiazhuang 050035, China
- Correspondence: (Z.L.); (Q.W.)
| | - Qinying Wang
- College of Plant Protection, Hebei Agricultural University, Baoding 071000, China
- Correspondence: (Z.L.); (Q.W.)
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17
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Belyy A, Lindemann F, Roderer D, Funk J, Bardiaux B, Protze J, Bieling P, Oschkinat H, Raunser S. Mechanism of threonine ADP-ribosylation of F-actin by a Tc toxin. Nat Commun 2022; 13:4202. [PMID: 35858890 PMCID: PMC9300711 DOI: 10.1038/s41467-022-31836-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 07/01/2022] [Indexed: 11/25/2022] Open
Abstract
Tc toxins deliver toxic enzymes into host cells by a unique injection mechanism. One of these enzymes is the actin ADP-ribosyltransferase TccC3, whose activity leads to the clustering of the cellular cytoskeleton and ultimately cell death. Here, we show in atomic detail how TccC3 modifies actin. We find that the ADP-ribosyltransferase does not bind to G-actin but interacts with two consecutive actin subunits of F-actin. The binding of TccC3 to F-actin occurs via an induced-fit mechanism that facilitates access of NAD+ to the nucleotide binding pocket. The following nucleophilic substitution reaction results in the transfer of ADP-ribose to threonine-148 of F-actin. We demonstrate that this site-specific modification of F-actin prevents its interaction with depolymerization factors, such as cofilin, which impairs actin network turnover and leads to steady actin polymerization. Our findings reveal in atomic detail a mechanism of action of a bacterial toxin through specific targeting and modification of F-actin. Entomopathogenic bacteria used for pest control secrete potent Tc toxins. Here, the authors combine biochemistry, solution and solid-state NMR spectroscopy and cryo-EM to show in atomic detail how the toxin disrupts the host cell cytoskeleton and kills the target cell.
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Affiliation(s)
- Alexander Belyy
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Florian Lindemann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125, Berlin, Germany
| | - Daniel Roderer
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany.,Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125, Berlin, Germany
| | - Johanna Funk
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Benjamin Bardiaux
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 25-28 Rue du Docteur Roux, F-75015, Paris, France
| | - Jonas Protze
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125, Berlin, Germany
| | - Peter Bieling
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Hartmut Oschkinat
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125, Berlin, Germany.
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany.
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18
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Lázaro-Berenguer M, Paredes-Martínez F, Bel Y, Núñez-Ramírez R, Arias-Palomo E, Casino P, Ferré J. Structural and functional role of Domain I for the insecticidal activity of the Vip3Aa protein from Bacillus thuringiensis. Microb Biotechnol 2022; 15:2607-2618. [PMID: 35830334 PMCID: PMC9518980 DOI: 10.1111/1751-7915.14110] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 06/07/2022] [Accepted: 06/13/2022] [Indexed: 12/05/2022] Open
Abstract
Vip3 proteins are produced by Bacillus thuringiensis and are toxic against lepidopterans, reason why the vip3Aa gene has been introduced into cotton and corn to control agricultural pests. Recently, the structure of Vip3 proteins has been determined and consists of a tetramer where each monomer is composed of five structural domains. The transition from protoxin to the trypsin‐activated form involves a major conformational change of the N‐terminal Domain I, which is remodelled into a tetrameric coiled‐coil structure that is thought to insert into the apical membrane of the midgut cells. To better understand the relevance of this major change in Domain I for the insecticidal activity, we have generated several mutants aimed to alter the activity and remodelling capacity of this central region to understand its function. These mutants have been characterized by proteolytic processing, negative staining electron microscopy, and toxicity bioassays against Spodoptera exigua. The results show the crucial role of helix α1 for the insecticidal activity and in restraining the Domain I in the protoxin conformation, the importance of the remodelling of helices α2 and α3, the proteolytic processing that takes place between Domains I and II, and the role of the C‐t Domains IV and V to sustain the conformational change necessary for toxicity.
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Affiliation(s)
- Maria Lázaro-Berenguer
- Department of Genetics, Universitat de València, Burjassot, Spain.,Institut Universitari de Biotecnologia i Biomedicina BIOTECMED, Universitat de València, Burjassot, Spain
| | - Francisco Paredes-Martínez
- Institut Universitari de Biotecnologia i Biomedicina BIOTECMED, Universitat de València, Burjassot, Spain.,Department of Biochemistry and Molecular Biology, Universitat de València, Burjassot, Spain
| | - Yolanda Bel
- Department of Genetics, Universitat de València, Burjassot, Spain.,Institut Universitari de Biotecnologia i Biomedicina BIOTECMED, Universitat de València, Burjassot, Spain
| | | | | | - Patricia Casino
- Institut Universitari de Biotecnologia i Biomedicina BIOTECMED, Universitat de València, Burjassot, Spain.,Department of Biochemistry and Molecular Biology, Universitat de València, Burjassot, Spain.,CIBER de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain
| | - Juan Ferré
- Department of Genetics, Universitat de València, Burjassot, Spain.,Institut Universitari de Biotecnologia i Biomedicina BIOTECMED, Universitat de València, Burjassot, Spain
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19
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Dong S, Zheng W, Pinkerton N, Hansen J, Tikunova SB, Davis JP, Heissler SM, Kudryashova E, Egelman EH, Kudryashov DS. Photorhabdus luminescens TccC3 Toxin Targets the Dynamic Population of F-Actin and Impairs Cell Cortex Integrity. Int J Mol Sci 2022; 23:7026. [PMID: 35806028 PMCID: PMC9266650 DOI: 10.3390/ijms23137026] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 06/17/2022] [Accepted: 06/22/2022] [Indexed: 12/30/2022] Open
Abstract
Due to its essential role in cellular processes, actin is a common target for bacterial toxins. One such toxin, TccC3, is an effector domain of the ABC-toxin produced by entomopathogenic bacteria of Photorhabdus spp. Unlike other actin-targeting toxins, TccC3 uniquely ADP-ribosylates actin at Thr-148, resulting in the formation of actin aggregates and inhibition of phagocytosis. It has been shown that the fully modified F-actin is resistant to depolymerization by cofilin and gelsolin, but their effects on partially modified actin were not explored. We found that only F-actin unprotected by tropomyosin is the physiological TccC3 substrate. Yet, ADP-ribosylated G-actin can be produced upon cofilin-accelerated F-actin depolymerization, which was only mildly inhibited in partially modified actin. The affinity of TccC3-ADP-ribosylated G-actin for profilin and thymosin-β4 was weakened moderately but sufficiently to potentiate spontaneous polymerization in their presence. Interestingly, the Arp2/3-mediated nucleation was also potentiated by T148-ADP-ribosylation. Notably, even partially modified actin showed reduced bundling by plastins and α-actinin. In agreement with the role of these and other tandem calponin-homology domain actin organizers in the assembly of the cortical actin network, TccC3 induced intense membrane blebbing in cultured cells. Overall, our data suggest that TccC3 imposes a complex action on the cytoskeleton by affecting F-actin nucleation, recycling, and interaction with actin-binding proteins involved in the integration of actin filaments with each other and cellular elements.
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Affiliation(s)
- Songyu Dong
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; (S.D.); (N.P.); (J.H.); (E.K.)
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA
| | - Weili Zheng
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22903, USA; (W.Z.); (E.H.E.)
| | - Nicholas Pinkerton
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; (S.D.); (N.P.); (J.H.); (E.K.)
| | - Jacob Hansen
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; (S.D.); (N.P.); (J.H.); (E.K.)
| | - Svetlana B. Tikunova
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA; (S.B.T.); (J.P.D.); (S.M.H.)
| | - Jonathan P. Davis
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA; (S.B.T.); (J.P.D.); (S.M.H.)
| | - Sarah M. Heissler
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA; (S.B.T.); (J.P.D.); (S.M.H.)
| | - Elena Kudryashova
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; (S.D.); (N.P.); (J.H.); (E.K.)
| | - Edward H. Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22903, USA; (W.Z.); (E.H.E.)
| | - Dmitri S. Kudryashov
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; (S.D.); (N.P.); (J.H.); (E.K.)
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA
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20
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Jiang F, Shen J, Cheng J, Wang X, Yang J, Li N, Gao N, Jin Q. N-terminal signal peptides facilitate the engineering of PVC complex as a potent protein delivery system. SCIENCE ADVANCES 2022; 8:eabm2343. [PMID: 35486720 PMCID: PMC9054023 DOI: 10.1126/sciadv.abm2343] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 02/11/2022] [Indexed: 06/14/2023]
Abstract
Extracellular contractile injection systems (eCISs) are widespread bacterial nanomachines that resemble T4 phage tail. As a typical eCIS, Photorhabdus virulence cassette (PVC) was proposed to inject toxins into eukaryotic cells by puncturing the cell membrane from outside. This makes it an ideal tool for protein delivery in biomedical research. However, how to manipulate this nanocomplex as a molecular syringe is still undetermined. Here, we identify that one group of N-terminal signal peptide (SP) sequences are crucial for the effector loading into the inner tube of PVC complex. By application of genetic operation, cryo-electron microscopy, in vitro translocation assays, and animal experiments, we show that, under the guidance of the SP, numerous prokaryotic and eukaryotic proteins can be loaded into PVC to exert their functions across cell membranes. We therefore might customize PVC as a potent protein delivery nanosyringe for biotherapy by selecting cargo proteins in a broad spectrum, regardless of their species, sizes, and charges.
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Affiliation(s)
- Feng Jiang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
| | - Jiawei Shen
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
| | - Jiaxuan Cheng
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, P. R. China
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, P. R. China
| | - Xia Wang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
| | - Jianguo Yang
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences, Peking University, Beijing, P. R. China
| | - Ningning Li
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, P. R. China
| | - Ning Gao
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, P. R. China
| | - Qi Jin
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
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21
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Schirmer B, Giehl K, Kubatzky KF. Report of the 24th Meeting on Signal Transduction 2021. Int J Mol Sci 2022; 23:ijms23042015. [PMID: 35216127 PMCID: PMC8877372 DOI: 10.3390/ijms23042015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 02/08/2022] [Indexed: 02/01/2023] Open
Abstract
The annual meeting “Signal Transduction—Receptors, Mediators and Genes” of the Signal Transduction Society (STS) is an interdisciplinary conference which is open to all scientists sharing a common interest in the elucidation of the signaling pathways mediating physiological or pathological processes in the health and disease of humans, animals, plants, fungi, prokaryotes, and protists. The 24th meeting on signal transduction was held from 15 to 17 November 2021 in Weimar, Germany. As usual, keynote presentations by invited scientists introduced the respective workshops, and were followed by speakers chosen from the submitted abstracts. A special workshop focused on “Target Identification and Interaction”. Ample time was reserved for the discussion of the presented data during the workshops. Unfortunately, due to restrictions owing to the SARS-CoV-2 pandemic, the poster sessions—and thus intensive scientific discussions at the posters—were not possible. In this report, we provide a concise summary of the various workshops and further aspects of the scientific program.
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Affiliation(s)
- Bastian Schirmer
- Institut für Pharmakologie, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625 Hannover, Germany;
| | - Klaudia Giehl
- Signaltransduktion Zellulärer Motilität, Innere Medizin V, Justus-Liebig-Universität Giessen, Aulweg 128, 35392 Giessen, Germany;
| | - Katharina F. Kubatzky
- Zentrum für Infektiologie, Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
- Correspondence: ; Tel.: +49-6221-56-38361
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22
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Massey JH, Newton ILG. Diversity and function of arthropod endosymbiont toxins. Trends Microbiol 2022; 30:185-198. [PMID: 34253453 PMCID: PMC8742837 DOI: 10.1016/j.tim.2021.06.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 02/03/2023]
Abstract
Bacterial endosymbionts induce dramatic phenotypes in their arthropod hosts, including cytoplasmic incompatibility, feminization, parthenogenesis, male killing, parasitoid defense, and pathogen blocking. The molecular mechanisms underlying these effects remain largely unknown but recent evidence suggests that protein toxins secreted by the endosymbionts play a role. Here, we describe the diversity and function of endosymbiont proteins with homology to known bacterial toxins. We focus on maternally transmitted endosymbionts belonging to the Wolbachia, Rickettsia, Arsenophonus, Hamiltonella, Spiroplasma, and Cardinium genera because of their ability to induce the above phenotypes. We identify at least 16 distinct toxin families with diverse enzymatic activities, including AMPylases, nucleases, proteases, and glycosyltransferases. Notably, several annotated toxins contain domains with homology to eukaryotic proteins, suggesting that arthropod endosymbionts mimic host biochemistry to manipulate host physiology, similar to bacterial pathogens.
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Affiliation(s)
| | - Irene L. G. Newton
- Department of Biology, Indiana University, Bloomington, Indiana, USA,Corresponding author,
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23
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Selberherr E, Penz T, König L, Conrady B, Siegl A, Horn M, Schmitz-Esser S. The life cycle-dependent transcriptional profile of the obligate intracellular amoeba symbiont Amoebophilus asiaticus. FEMS Microbiol Ecol 2022; 98:6499296. [PMID: 34999767 PMCID: PMC8831229 DOI: 10.1093/femsec/fiac001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/22/2021] [Accepted: 01/04/2022] [Indexed: 12/04/2022] Open
Abstract
Free-living amoebae often harbor obligate intracellular bacterial symbionts. Amoebophilus (A.) asiaticus is a representative of a lineage of amoeba symbionts in the phylum Bacteroidota. Here, we analyse the transcriptome of A. asiaticus strain 5a2 at four time points during its infection cycle and replication within the Acanthamoeba host using RNA sequencing. Our results reveal a dynamic transcriptional landscape throughout different A. asiaticus life cycle stages. Many intracellular bacteria and pathogens utilize eukaryotic-like proteins (ELPs) for host cell interaction and the A. asiaticus 5a2 genome shows a particularly high abundance of ELPs. We show the expression of all genes encoding ELPs and found many ELPs to be differentially expressed. At the replicative stage of A. asiaticus, ankyrin repeat proteins and tetratricopeptide/Sel1-like repeat proteins were upregulated. At the later time points, high expression levels of a type 6 secretion system that likely prepares for a new infection cycle after lysing its host, were found. This study reveals comprehensive insights into the intracellular lifestyle of A. asiaticus and highlights candidate genes for host cell interaction. The results from this study have implications for other intracellular bacteria such as other amoeba-associated bacteria and the arthropod symbionts Cardinium forming the sister lineage of A. asiaticus.
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Affiliation(s)
- E Selberherr
- Unit of Food Microbiology, Institute of Food Safety, Food Technology and Veterinary Public Health, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine Vienna, Austria
| | - T Penz
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria.,current affiliation: CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - L König
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - B Conrady
- Department of Veterinary and Animal Science, University of Copenhagen, Denmark
| | - A Siegl
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - M Horn
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - S Schmitz-Esser
- Department of Animal Science, Iowa State University, Ames, USA
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24
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Günther P, Quentin D, Ahmad S, Sachar K, Gatsogiannis C, Whitney JC, Raunser S. Structure of a bacterial Rhs effector exported by the type VI secretion system. PLoS Pathog 2022; 18:e1010182. [PMID: 34986192 PMCID: PMC8765631 DOI: 10.1371/journal.ppat.1010182] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 01/18/2022] [Accepted: 12/08/2021] [Indexed: 11/20/2022] Open
Abstract
The type VI secretion system (T6SS) is a widespread protein export apparatus found in Gram-negative bacteria. The majority of T6SSs deliver toxic effector proteins into competitor bacteria. Yet, the structure, function, and activation of many of these effectors remains poorly understood. Here, we present the structures of the T6SS effector RhsA from Pseudomonas protegens and its cognate T6SS spike protein, VgrG1, at 3.3 Å resolution. The structures reveal that the rearrangement hotspot (Rhs) repeats of RhsA assemble into a closed anticlockwise β-barrel spiral similar to that found in bacterial insecticidal Tc toxins and in metazoan teneurin proteins. We find that the C-terminal toxin domain of RhsA is autoproteolytically cleaved but remains inside the Rhs ‘cocoon’ where, with the exception of three ordered structural elements, most of the toxin is disordered. The N-terminal ‘plug’ domain is unique to T6SS Rhs proteins and resembles a champagne cork that seals the Rhs cocoon at one end while also mediating interactions with VgrG1. Interestingly, this domain is also autoproteolytically cleaved inside the cocoon but remains associated with it. We propose that mechanical force is required to remove the cleaved part of the plug, resulting in the release of the toxin domain as it is delivered into a susceptible bacterial cell by the T6SS. Bacteria have developed a variety of strategies to compete for nutrients and limited resources. One system widely used by Gram-negative bacteria is the T6 secretion system which delivers a plethora of effectors into competing bacterial cells. Known functions of effectors are degradation of the cell wall, the depletion of essential metabolites such as NAD+ or the cleavage of DNA. RhsA is an effector from the widespread plant-protecting bacteria Pseudomonas protegens. We found that RhsA forms a closed cocoon similar to that found in bacterial Tc toxins and metazoan teneurin proteins. The effector cleaves its polypeptide chain by itself in three pieces, namely the N-terminal domain including a seal, the cocoon and the actual toxic component which potentially cleaves DNA. The toxic component is encapsulated in the large cocoon, so that the effector producing bacterium is protected from the toxin. In order for the toxin to exit the cocoon, we propose that the seal, which closes the cocoon at one end, is removed by mechanical forces during injection of the effector by the T6 secretion system. We further hypothesize about different scenarios for the delivery of the toxin into the cytoplasm of the host cell. Together, our findings expand the knowledge of the mechanism of action of the T6 secretion system and its essential role in interbacterial competition.
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Affiliation(s)
- Patrick Günther
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Dennis Quentin
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Shehryar Ahmad
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Kartik Sachar
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Christos Gatsogiannis
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - John C. Whitney
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Canada
- David Braley Centre for Antibiotic Discovery, McMaster University, Hamilton, Canada
- * E-mail: (J.C.W.); (S.R.)
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
- * E-mail: (J.C.W.); (S.R.)
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25
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Abstract
Protein toxins secreted by prokaryotes have been found to affect the pathogenicity of pathogens or directly mediate antagonistic interactions between prokaryotes. PAAR proteins are important carriers of toxic effectors and are located at the forefront of either the type VI secretion system (T6SS) or the extracellular contractile injection system (eCIS). This study systematically investigated PAAR homologues and related toxic effectors. We found that PAAR homologues were divided into 8 types and 16 subtypes and distributed in 23.1% of bacterial genomes and 7.8% of archaeal genomes. PAAR proteins of all types fold into a highly similar conical structure, even from relatively diverse underlying sequences. PAAR homologues associated with different secretion systems display a mixed phylogenetic relationship, indicating that PAAR proteins from such a subtype can be assembled on either a T6SS or an eCIS. More than 1,300 PAAR-related toxic effector genes were identified; one PAAR subtype can be associated with toxins of over 40 families, and toxins from one family can be associated with more than 10 PAAR subtypes. A large-scale comparison of Earth Microbiome Project data and prokaryotic genomes revealed that prokaryotes encoding PAAR genes are widely present in diverse environments worldwide, and taxa encoding multiple PAAR gene copies exhibit a wider distribution in environments than other taxa. Overall, our studies highlighted that PAAR proteins are versatile clips loaded with antimicrobial toxin bullets for secretion weapons (T6SS and eCIS), greatly enriching the weapon arsenal of prokaryotes, which, often together with VgrG, help prokaryotes fight for survival advantages in crowded environments. IMPORTANCE Infectious diseases caused by microbial pathogens are severe threats to human health and economic development. To respond to these threats, it is necessary to understand how microorganisms survive in and adapt to complex environments. Microorganic toxins, which are widely distributed in nature, are the key weapons in life domain interactions. PAAR proteins are important carriers of prokaryotic toxic effectors. We reveal the versatility of PAAR proteins between secretory systems and the massive diversity of toxic effectors carried by PAAR proteins, which helps prokaryotes enrich their arsenal and expand their ability to attack their neighbors. A large number of PAAR homologues and related toxic effectors enhance the survival competitiveness of prokaryotic populations. In conclusion, our work provides an example for large-scale analysis of the global distribution and ecological functions of prokaryotic functional genes.
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26
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Mounting, structure and autocleavage of a type VI secretion-associated Rhs polymorphic toxin. Nat Commun 2021; 12:6998. [PMID: 34853317 PMCID: PMC8636562 DOI: 10.1038/s41467-021-27388-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 11/15/2021] [Indexed: 12/30/2022] Open
Abstract
Bacteria have evolved toxins to outcompete other bacteria or to hijack host cell pathways. One broad family of bacterial polymorphic toxins gathers multidomain proteins with a modular organization, comprising a C-terminal toxin domain fused to a N-terminal domain that adapts to the delivery apparatus. Polymorphic toxins include bacteriocins, contact-dependent growth inhibition systems, and specialized Hcp, VgrG, PAAR or Rhs Type VI secretion (T6SS) components. We recently described and characterized Tre23, a toxin domain fused to a T6SS-associated Rhs protein in Photorhabdus laumondii, Rhs1. Here, we show that Rhs1 forms a complex with the T6SS spike protein VgrG and the EagR chaperone. Using truncation derivatives and cross-linking mass spectrometry, we demonstrate that VgrG-EagR-Rhs1 complex formation requires the VgrG C-terminal β-helix and the Rhs1 N-terminal region. We then report the cryo-electron-microscopy structure of the Rhs1-EagR complex, demonstrating that the Rhs1 central region forms a β-barrel cage-like structure that encapsulates the C-terminal toxin domain, and provide evidence for processing of the Rhs1 protein through aspartyl autoproteolysis. We propose a model for Rhs1 loading on the T6SS, transport and delivery into the target cell.
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27
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Hurst MRH, Beattie A, Laugraud A, Townsend R, Sitter L, van Koten C, Harper L. Identification of Diverse Toxin Complex Clusters and an eCIS Variant in Serratia proteamaculans Pathovars of the New Zealand Grass Grub ( Costelytra Giveni) and Manuka Beetle ( Pyronota Spp.) Larvae. Microbiol Spectr 2021; 9:e0112321. [PMID: 34668742 PMCID: PMC8528098 DOI: 10.1128/spectrum.01123-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 09/08/2021] [Indexed: 12/01/2022] Open
Abstract
The grass grub endemic to New Zealand, Costelytra giveni (Coleoptera: Scarabaeidae), and the manuka beetle, Pyronota festiva and P. setosa (Coleoptera: Scarabaeidae), are prevalent pest species. Through assessment of bacterial strains isolated from diseased cadavers of these insect species, 19 insect-active Serratia proteamaculans variants and a single Serratia entomophila strain were isolated. When independently bioassayed, these isolates differed in host range, the rate of disease progression, and 12-day mortality rates, which ranged from 60 to 100% of the challenged larvae. A Pyronota spp.-derived S. proteamaculans isolate caused a transient disease phenotype in challenged C. giveni larvae, whereby larvae appeared diseased before recovering to a healthy state. Genome sequence analysis revealed that all but two of the sequenced isolates contained a variant of the S. entomophila amber-disease-associated plasmid, pADAP. Each isolate also encoded one of seven distinct members of the toxin complex (Tc) family of insect-active toxins, five of which are newly described, or a member of the extracellular contractile injection (eCIS) machine family, with a new AfpX variant designated SpF. Targeted mutagenesis of each of the predicted Tc- or eCIS-encoding regions abolished or attenuated pathogenicity. Host-range testing showed that several of the S. proteamaculans Tc-encoding isolates affected both Pyronota and C. giveni species, with other isolates specific for either Pyronota spp. or C. giveni. The isolation of several distinct host-specific pathotypes of Serratia spp. may reflect pathogen-host speciation. IMPORTANCE New pathotypes of the insect pathogen Serratia, each with differing virulence attributes and host specificity toward larvae of the New Zealand manuka beetle and grass grub, have been identified. All of the Serratia proteamaculans isolates contained one of seven different insect-active toxin clusters or one of three eCIS variants. The diversity of these Serratia-encoded virulence clusters, resulting in differences in larval disease progression and host specificity in endemic scarab larvae, suggests speciation of these pathogens with their insect hosts. The differing virulence properties of these Serratia species may affect their potential infectivity and distribution among the insect populations. Based on their differing geographic isolation and pathotypes, several of these Serratia isolates, including the manuka beetle-active isolates, are likely to be more effective biopesticides in specific environments or could be used in combination for greater effect.
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Affiliation(s)
- Mark R. H. Hurst
- Resilient Agriculture, AgResearch, Lincoln Research Centre, Christchurch, New Zealand
- Bio-Protection Research Centre, Lincoln University, Christchurch, New Zealand
| | - Amy Beattie
- Resilient Agriculture, AgResearch, Lincoln Research Centre, Christchurch, New Zealand
| | - Aurelie Laugraud
- Knowledge & Analytics, AgResearch, Lincoln Research Centre, Christchurch, New Zealand
| | - Richard Townsend
- Resilient Agriculture, AgResearch, Lincoln Research Centre, Christchurch, New Zealand
| | - Lesley Sitter
- Resilient Agriculture, AgResearch, Lincoln Research Centre, Christchurch, New Zealand
- Bio-Protection Research Centre, Lincoln University, Christchurch, New Zealand
| | - Chikako van Koten
- Knowledge & Analytics, AgResearch, Lincoln Research Centre, Christchurch, New Zealand
| | - Lincoln Harper
- Curtin University, Centre for Crop and Disease Management, School of Molecular and Life, Bentley, Western Australia, Australia
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28
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Sannigrahi A, Chattopadhyay K. Pore formation by pore forming membrane proteins towards infections. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 128:79-111. [PMID: 35034727 DOI: 10.1016/bs.apcsb.2021.09.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Over the last 25 years, the biology of membrane proteins, including the PFPs-membranes interactions is seeking attention for the development of successful drug molecules against a number of infectious diseases. Pore forming toxins (PFTs), the largest family of PFPs are considered as a group of virulence factors produced in a large number of pathogenic systems which include streptococcus, pneumonia, Staphylococcus aureus, E. coli, Mycobacterium tuberculosis, group A and B streptococci, Corynebacterium diphtheria and many more. PFTs are generally utilized by the disease causing pathogens to disrupt the host first line of defense i.e. host cell membranes through pore formation strategy. Although, pore formation is the principal mode of action of the PFTs but they can have additional adverse effects on the hosts including immune evasion. Recently, structural investigation of different PFTs have imparted the molecular mechanistic insights into how PFTs get transformed from its inactive state to active toxic state. On the basis of their structural entity, PFTs have been classified in different types and their mode of actions alters in terms of pore formation and corresponding cellular toxicity. Although pathogen genome analysis can identify the probable PFTs depending upon their structural diversity, there are so many PFTs which utilize the local environmental conditions to generate their pore forming ability using a novel strategy which is known as "conformational switch" of a protein. This conformational switch is considered as characteristics of the phase shifting proteins which were often utilized by many pathogenic systems to protect them from the invaders through allosteric communication between distant regions of the protein. In this chapter, we discuss the structure function relationships of PFTs and how activity of PFTs varies with the change in the environmental conditions has been explored. Finally, we demonstrate these structural insights to develop therapeutic potential to treat the infections caused by multidrug resistant pathogens.
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Affiliation(s)
- Achinta Sannigrahi
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, Karnataka, India.
| | - Krishnananda Chattopadhyay
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, West Bengal, India.
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29
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Ng'ang'a PN, Siukstaite L, Lang AE, Bakker H, Römer W, Aktories K, Schmidt G. Involvement of N-glycans in binding of Photorhabdus luminescens Tc toxin. Cell Microbiol 2021; 23:e13326. [PMID: 33720490 DOI: 10.1111/cmi.13326] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 03/09/2021] [Accepted: 03/10/2021] [Indexed: 12/20/2022]
Abstract
Photorhabdus luminescens Tc toxins are large tripartite ABC-type toxin complexes, composed of TcA, TcB and TcC proteins. Tc toxins are widespread and have shown a tropism for a variety of targets including insect, mammalian and human cells. However, their receptors and the specific mechanisms of uptake into target cells remain unknown. Here, we show that the TcA protein TcdA1 interacts with N-glycans, particularly Lewis X/Y antigens. This is confirmed using N-acetylglucosamine transferase I (Mgat1 gene product)-deficient Chinese hamster ovary (CHO) Lec1 cells, which are highly resistant to intoxication by the Tc toxin complex most likely due to the absence of complex N-glycans. Restoring Mgat1 gene activity, and hence complex N-glycan biosynthesis, recapitulated the sensitivity of these cells to the toxin. Exogenous addition of Lewis X trisaccharide partially inhibits intoxication in wild-type cells. Additionally, sialic acid also largely reduced binding of the Tc toxin. Moreover, proteolytic activation of TcdA1 alters glycan-binding and uptake into target cells. The data suggest that TcdA1-binding is most likely multivalent, and carbohydrates probably work cooperatively to facilitate binding and intoxication.
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Affiliation(s)
- Peter Njenga Ng'ang'a
- Institute for Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Spemann Graduate School for Biology and Medicine, University of Freiburg, Freiburg, Germany
| | - Lina Siukstaite
- Faculty of Biology, University of Freiburg, Freiburg, Germany.,CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Alexander E Lang
- Institute for Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Hans Bakker
- Institut für Klinische Biochemie, Medizinische Hochschule Hannover, MHH, Hannover, Germany
| | - Winfried Römer
- Spemann Graduate School for Biology and Medicine, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany.,CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany.,BIOSS-Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany
| | - Klaus Aktories
- Institute for Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Spemann Graduate School for Biology and Medicine, University of Freiburg, Freiburg, Germany.,BIOSS-Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany
| | - Gudula Schmidt
- Institute for Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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30
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Desikan R, Behera A, Maiti PK, Ayappa KG. Using multiscale molecular dynamics simulations to obtain insights into pore forming toxin mechanisms. Methods Enzymol 2021; 649:461-502. [PMID: 33712196 DOI: 10.1016/bs.mie.2021.01.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Pore forming toxins (PFTs) are virulent proteins released by several species, including many strains of bacteria, to attack and kill host cells. In this article, we focus on the utility of molecular dynamics (MD) simulations and the molecular insights gleaned from these techniques on the pore forming pathways of PFTs. In addition to all-atom simulations which are widely used, coarse-grained MARTINI models and structure-based models have also been used to study PFTs. Here, the emphasis is on methods and techniques involved while setting up, monitoring, and evaluating properties from MD simulations of PFTs in a membrane environment. We draw from several case studies to illustrate how MD simulations have provided molecular insights into protein-protein and protein-lipid interactions, lipid dynamics, conformational transitions and structures of both the oligomeric intermediates and assembled pore structures.
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Affiliation(s)
- Rajat Desikan
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, India
| | - Amit Behera
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, India
| | - Prabal K Maiti
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bengaluru, India
| | - K Ganapathy Ayappa
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, India; Centre for Biosystems Science and Engineering, Indian Institute of Science, Bengaluru, India.
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31
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Johnstone BA, Christie MP, Morton CJ, Parker MW. X-ray crystallography shines a light on pore-forming toxins. Methods Enzymol 2021; 649:1-46. [PMID: 33712183 DOI: 10.1016/bs.mie.2021.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A common form of cellular attack by pathogenic bacteria is to secrete pore-forming toxins (PFTs). Capable of forming transmembrane pores in various biological membranes, PFTs have also been identified in a diverse range of other organisms such as sea anemones, earthworms and even mushrooms and trees. The mechanism of pore formation by PFTs is associated with substantial conformational changes in going from the water-soluble to transmembrane states of the protein. The determination of the crystal structures for numerous PFTs has shed much light on our understanding of these proteins. Other than elucidating the atomic structural details of PFTs and the conformational changes that must occur for pore formation, crystal structures have revealed structural homology that has led to the discovery of new PFTs and new PFT families. Here we review some key crystallographic results together with complimentary approaches for studying PFTs. We discuss how these studies have impacted our understanding of PFT function and guided research into biotechnical applications.
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Affiliation(s)
- Bronte A Johnstone
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Michelle P Christie
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Craig J Morton
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Michael W Parker
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia; St. Vincent's Institute of Medical Research, Fitzroy, VIC, Australia.
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32
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Song N, Chen L, Zhou Z, Ren X, Liu B, Zhou S, Wang C, Wu Y, Waterfield NR, Yang J, Yang G. Genome-wide dissection reveals diverse pathogenic roles of bacterial Tc toxins. PLoS Pathog 2021; 17:e1009102. [PMID: 33540421 PMCID: PMC7861908 DOI: 10.1371/journal.ppat.1009102] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 10/26/2020] [Indexed: 12/21/2022] Open
Abstract
Tc toxins were originally identified in entomopathogenic bacteria, which are important as biological pest control agents. Tc toxins are heteromeric exotoxins composed of three subunit types, TcA, TcB, and TcC. The C-terminal portion of the TcC protein encodes the actual toxic domain, which is translocated into host cells by an injectosome nanomachine comprising the other subunits. Currently the pathogenic roles and distribution of Tc toxins among different bacterial genera remain unclear. Here we have performed a comprehensive genome-wide analysis, and established a database that includes 1,608 identified Tc loci containing 2,528 TcC proteins in 1,421 Gram-negative and positive bacterial genomes. Our findings indicate that TcCs conform to the architecture of typical polymorphic toxins, with C-terminal hypervariable regions (HVR) encoding more than 100 different classes of putative toxic domains, most of which have not been previously recognized. Based on further analysis of Tc loci in the genomes of all Salmonella and Yersinia strains in EnteroBase, a “two-level” evolutionary dynamics scenario is proposed for TcC homologues. This scenario implies that the conserved TcC RHS core domain plays a critical role in the taxonomical specific distribution of TcC HVRs. This study provides an extensive resource for the future development of Tc toxins as valuable agrochemical tools. It furthermore implies that Tc proteins, which are encoded by a wide range of pathogens, represent an important versatile toxin superfamily with diverse pathogenic mechanisms. Entomopathogenic bacteria deploy a range of toxins to combat their insect hosts. The Tc toxins were first identified in Photorhabdus as having potent oral toxicity to insects, with a mode of action distinct from the well-studied Bacillus thuringiensis Cry toxins. As such the Tc toxins have been considered as potential candidates for novel crop protection strategies. This could mitigate against the potential risks of pest insects developing resistance to the traditionally used Cry toxin-based systems. To date, the generality of diverse Tc toxins and their related pathogenic roles has remained mainly obscure. Our analysis has showed Tc toxins are widely distributed among Gram-negative and positive bacterial genomes. A database was constructed including thousands of Tc loci with hundreds of different putative TcC toxic domains, any one of which might represent candidates for the development of future pest control systems. Moreover, the findings of this study are of wider significance because Tc toxin homologues have been shown to be encoded by a range of human pathogens. These include Salmonella and Yersinia, suggesting their potential roles in human infectious diseases. Together, this study describes the characteristics and distribution of Tc toxins among diverse bacterial genera, and provides a new insight into their roles in different pathogenesis mechanisms. This study also describes findings of potential importance to their development as tools for biotechnological applications.
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Affiliation(s)
- Nan Song
- Beijing Institute of Tropical Medicine, Beijing, China
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Lihong Chen
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Zhemin Zhou
- Warwick Medical School, Warwick University, Coventry, United Kingdom
| | - Xingmei Ren
- Beijing Institute of Tropical Medicine, Beijing, China
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Bo Liu
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Siyu Zhou
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Caihong Wang
- Beijing Institute of Tropical Medicine, Beijing, China
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Yun Wu
- Beijing Institute of Tropical Medicine, Beijing, China
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | | | - Jian Yang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- * E-mail: (JY); (GY)
| | - Guowei Yang
- Beijing Institute of Tropical Medicine, Beijing, China
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- * E-mail: (JY); (GY)
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Song N, Chen L, Ren X, Waterfield NR, Yang J, Yang G. N-Glycans and sulfated glycosaminoglycans contribute to the action of diverse Tc toxins on mammalian cells. PLoS Pathog 2021; 17:e1009244. [PMID: 33539469 PMCID: PMC7861375 DOI: 10.1371/journal.ppat.1009244] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 12/18/2020] [Indexed: 01/11/2023] Open
Abstract
Tc toxin is an exotoxin composed of three subunits named TcA, TcB and TcC. Structural analysis revealed that TcA can form homopentamer that mediates the cellular recognition and delivery processes, thus contributing to the host tropism of Tc toxin. N-glycans and heparan sulfates have been shown to act as receptors for several Tc toxins. Here, we performed two independent genome-wide CRISPR-Cas9 screens, and have validated glycans and sulfated glycosaminoglycans (sGAGs) as Tc toxin receptors also for previously uncharacterized Tc toxins. We found that TcdA1 form Photorhabdus luminescens W14 (TcdA1W14) can recognize N-glycans via the RBD-D domain, corroborating previous findings. Knockout of N-glycan processing enzymes specifically blocks the intoxication of TcdA1W14-assembled Tc toxin. On the other hand, our results showed that sGAG biosynthesis pathway is involved in the cell surface binding of TcdA2TT01 (TcdA2 from P. luminescens TT01). Competition assays and biolayer interferometry demonstrated that the sulfation group in sGAGs is required for the binding of TcdA2TT01. Finally, based on the conserved domains of representative TcA proteins, we have identified 1,189 putative TcAs from 1,039 bacterial genomes. These TcAs are categorized into five subfamilies. Each subfamily shows a good correlation with both genetic organization of the TcA protein(s) and taxonomic origin of the genomes, suggesting these subfamilies may utilize different mechanisms for cellular recognition. Taken together, our results support the previously described two different binding modalities of Tc toxins, leading to unique host targeting properties. We also present the bioinformatics data and receptor screening strategies for TcA proteins, provide new insights into understanding host specificity and biomedical applications of Tc toxins. The Toxin complexes, also referred to as Tc toxins, are a family of A5BC exotoxins widely distributed among Gram-negative and positive bacteria. First identified in Entomopathogenic bacteria as key virulence factors to combat insect hosts, putative Tc toxin loci are also encoded by a range of human pathogens such as Salmonella and Yersinia. Previous studies indicated that several Tc toxins can target invertebrate and vertebrate cells via binding with N-glycans and heparan sulfates. Here our genome-wide CRISPR-Cas9 screens validated that different Tc toxins utilized distinct receptors for the adhesion to their targets, which is determined by TcA homopentamer. For example, TcdA1 from Photorhabdus luminescens W14 (TcdA1W14) relies on N-glycan binding to exert its toxic effects, while sulfate groups of sulfated glycosaminoglycans are critical for the cell targeting of other TcAs such as TcdA2TT01 (TcdA2 from P. luminescens TT01). Consistent with the previously described different binding modalities of Tc toxins, our results confirm that the receptor selectivity of TcAs contribute to the cellular tropism of Tc toxins. Furthermore we has also identified 1,189 TcA homologues and categorized them into five subfamilies. Each TcA subfamily shows a good correlation with the taxonomic origin of the genomes, suggesting these subfamilies are linked to diverse host tropisms via different binding modalities. Together, our findings provide mechanistic insights into understanding host specificity of distinct Tc toxins and the development of therapeutics for Tc toxin-related infections, as well as the adaptation of Tc-injectisomes as potential biotechnology tools and pest-control weapons.
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Affiliation(s)
- Nan Song
- Beijing Institute of Tropical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Lihong Chen
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xingmei Ren
- Beijing Institute of Tropical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | | | - Jian Yang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Guowei Yang
- Beijing Institute of Tropical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- * E-mail:
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Keskes S, Jallouli W, Atitallah IB, Driss F, Sahli E, Chamkha M, Tounsi S. Development of a cost-effective medium for Photorhabdus temperata bioinsecticide production from wastewater and exploration of performance kinetic. Sci Rep 2021; 11:779. [PMID: 33436984 PMCID: PMC7804953 DOI: 10.1038/s41598-020-80773-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 12/22/2020] [Indexed: 01/29/2023] Open
Abstract
This study investigates the optimization of the culture conditions for enhancing Photorhabdus temperata biopesticide production using wastewater (WS4) as a raw material. Box-Behnken design (BBD) was used to evaluate the effects of carbon to nitrogen ratio (C/N), sodium chloride concentration and inoculum size on P. temperata biomass production and insecticidal activity. For an enhanced biopesticide production, the optimum operating conditions were as follows: inoculum size = 4%; C/N ratio = 12.5 and [NaCl] = 4 g/L for two responses. 1.95 and 2.75 fold improvements in oral toxicity and biomass production were respectively obtained in the cost-effective medium developed in this study (WS4 I) using the three variables at their optimal values. Under the optimized conditions, WS4 I-grown cells exhibited higher membrane integrity according to flow cytometry analysis since dead cells presented only 9.2% compared to 29.2% in WS4. From batch fermentations carried out in WS4 I and WS4, P. temperata kinetic parameters in terms of biomass production and substrate consumption rates were modeled. The obtained results showed that the maximum specific growth rate in WS4 I was of 0.43 h-1 while that obtained in WS4 was of 0.14 h-1. In addition, the efficiency of P. temperata to metabolize organic carbon was enhanced by optimizing the culture conditions. It reached 72.66% instead of 46.18% in the control fermentation after 10 h of incubation. Under the optimized conditions, P. temperata cells showed the highest specific consumption rate resulting in a toxin synthesis improvement.
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Affiliation(s)
- Sahar Keskes
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, Sfax University, P.O. Box '1177', 3018, Sfax, Tunisia
| | - Wafa Jallouli
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, Sfax University, P.O. Box '1177', 3018, Sfax, Tunisia.
| | - Imen Ben Atitallah
- Laboratory of Enzyme Engineering and Microbiology, National School of Engineering of Sfax (ENIS), Sfax University, BP 1173, 3038, Sfax, Tunisia
| | - Fatma Driss
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, Sfax University, P.O. Box '1177', 3018, Sfax, Tunisia
| | - Emna Sahli
- Analysis Laboratory, Centre of Biotechnology of Sfax, Sfax University, P.O. Box '1177', 3018, Sfax, Tunisia
| | - Mohamed Chamkha
- Laboratory of Environmental Bioprocesses, Centre of Biotechnology of Sfax, Sfax University, P.O. Box '1177', 3018, Sfax, Tunisia
| | - Slim Tounsi
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, Sfax University, P.O. Box '1177', 3018, Sfax, Tunisia
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Pereira J, Lupas AN. The VCBS superfamily forms a third supercluster of β-propellers that includes tachylectin and integrins. Bioinformatics 2021; 36:5618-5622. [PMID: 33416871 PMCID: PMC8023676 DOI: 10.1093/bioinformatics/btaa1085] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 12/14/2020] [Accepted: 12/21/2020] [Indexed: 01/15/2023] Open
Abstract
MOTIVATION β-Propellers are found in great variety across all kingdoms of life. They assume many cellular roles, primarily as scaffolds for macromolecular interactions and catalysis. Despite their diversity, most β-propeller families clearly originated by amplification from the same ancient peptide-the "blade". In cluster analyses, β-propellers of the WD40 superfamily always formed the largest group, to which some important families, such as the α-integrin, Asp-box, and glycoside hydrolase β-propellers connected weakly. Motivated by the dramatic growth of sequence databases we revisited these connections, with a special focus on VCBS-like β-propellers, which have not been analysed for their evolutionary relationships so far. RESULTS We found that VCBS-like form a supercluster with integrin-like β-propellers and tachylectins, clearly delimited from the superclusters formed by WD40 and Asp-Box β-propellers. Connections between the three superclusters are made mainly through PQQ-like β-propeller. Our results present a new, greatly expanded view of the β-propeller classification landscape. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Joana Pereira
- Department of Protein Evolution, Max-Planck-Institute for Developmental Biology, Tübingen, 72076, Germany
| | - Andrei N Lupas
- Department of Protein Evolution, Max-Planck-Institute for Developmental Biology, Tübingen, 72076, Germany
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Fake It 'Till You Make It-The Pursuit of Suitable Membrane Mimetics for Membrane Protein Biophysics. Int J Mol Sci 2020; 22:ijms22010050. [PMID: 33374526 PMCID: PMC7793082 DOI: 10.3390/ijms22010050] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 12/17/2020] [Accepted: 12/19/2020] [Indexed: 12/13/2022] Open
Abstract
Membrane proteins evolved to reside in the hydrophobic lipid bilayers of cellular membranes. Therefore, membrane proteins bridge the different aqueous compartments separated by the membrane, and furthermore, dynamically interact with their surrounding lipid environment. The latter not only stabilizes membrane proteins, but directly impacts their folding, structure and function. In order to be characterized with biophysical and structural biological methods, membrane proteins are typically extracted and subsequently purified from their native lipid environment. This approach requires that lipid membranes are replaced by suitable surrogates, which ideally closely mimic the native bilayer, in order to maintain the membrane proteins structural and functional integrity. In this review, we survey the currently available membrane mimetic environments ranging from detergent micelles to bicelles, nanodiscs, lipidic-cubic phase (LCP), liposomes, and polymersomes. We discuss their respective advantages and disadvantages as well as their suitability for downstream biophysical and structural characterization. Finally, we take a look at ongoing methodological developments, which aim for direct in-situ characterization of membrane proteins within native membranes instead of relying on membrane mimetics.
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The β-encapsulation cage of rearrangement hotspot (Rhs) effectors is required for type VI secretion. Proc Natl Acad Sci U S A 2020; 117:33540-33548. [PMID: 33323487 DOI: 10.1073/pnas.1919350117] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Bacteria deploy rearrangement hotspot (Rhs) proteins as toxic effectors against both prokaryotic and eukaryotic target cells. Rhs proteins are characterized by YD-peptide repeats, which fold into a large β-cage structure that encapsulates the C-terminal toxin domain. Here, we show that Rhs effectors are essential for type VI secretion system (T6SS) activity in Enterobacter cloacae (ECL). ECL rhs - mutants do not kill Escherichia coli target bacteria and are defective for T6SS-dependent export of hemolysin-coregulated protein (Hcp). The RhsA and RhsB effectors of ECL both contain Pro-Ala-Ala-Arg (PAAR) repeat domains, which bind the β-spike of trimeric valine-glycine repeat protein G (VgrG) and are important for T6SS activity in other bacteria. Truncated RhsA that retains the PAAR domain is capable of forming higher-order, thermostable complexes with VgrG, yet these assemblies fail to restore secretion activity to ∆rhsA ∆rhsB mutants. Full T6SS-1 activity requires Rhs that contains N-terminal transmembrane helices, the PAAR domain, and an intact β-cage. Although ∆rhsA ∆rhsB mutants do not kill target bacteria, time-lapse microscopy reveals that they assemble and fire T6SS contractile sheaths at ∼6% of the frequency of rhs + cells. Therefore, Rhs proteins are not strictly required for T6SS assembly, although they greatly increase secretion efficiency. We propose that PAAR and the β-cage provide distinct structures that promote secretion. PAAR is clearly sufficient to stabilize trimeric VgrG, but efficient assembly of T6SS-1 also depends on an intact β-cage. Together, these domains enforce a quality control checkpoint to ensure that VgrG is loaded with toxic cargo before assembling the secretion apparatus.
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Tremblay O, Thow Z, Merrill AR. Several New Putative Bacterial ADP-Ribosyltransferase Toxins Are Revealed from In Silico Data Mining, Including the Novel Toxin Vorin, Encoded by the Fire Blight Pathogen Erwinia amylovora. Toxins (Basel) 2020; 12:E792. [PMID: 33322547 PMCID: PMC7764402 DOI: 10.3390/toxins12120792] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 11/28/2020] [Accepted: 12/10/2020] [Indexed: 12/31/2022] Open
Abstract
Mono-ADP-ribosyltransferase (mART) toxins are secreted by several pathogenic bacteria that disrupt vital host cell processes in deadly diseases like cholera and whooping cough. In the last two decades, the discovery of mART toxins has helped uncover the mechanisms of disease employed by pathogens impacting agriculture, aquaculture, and human health. Due to the current abundance of mARTs in bacterial genomes, and an unprecedented availability of genomic sequence data, mART toxins are amenable to discovery using an in silico strategy involving a series of sequence pattern filters and structural predictions. In this work, a bioinformatics approach was used to discover six bacterial mART sequences, one of which was a functional mART toxin encoded by the plant pathogen, Erwinia amylovora, called Vorin. Using a yeast growth-deficiency assay, we show that wild-type Vorin inhibited yeast cell growth, while catalytic variants reversed the growth-defective phenotype. Quantitative mass spectrometry analysis revealed that Vorin may cause eukaryotic host cell death by suppressing the initiation of autophagic processes. The genomic neighbourhood of Vorin indicated that it is a Type-VI-secreted effector, and co-expression experiments showed that Vorin is neutralized by binding of a cognate immunity protein, VorinI. We demonstrate that Vorin may also act as an antibacterial effector, since bacterial expression of Vorin was not achieved in the absence of VorinI. Vorin is the newest member of the mART family; further characterization of the Vorin/VorinI complex may help refine inhibitor design for mART toxins from other deadly pathogens.
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Affiliation(s)
| | | | - A. Rod Merrill
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada; (O.T.); (Z.T.)
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Pore-forming proteins: From defense factors to endogenous executors of cell death. Chem Phys Lipids 2020; 234:105026. [PMID: 33309552 DOI: 10.1016/j.chemphyslip.2020.105026] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 12/07/2020] [Accepted: 12/07/2020] [Indexed: 02/06/2023]
Abstract
Pore-forming proteins (PFPs) and small antimicrobial peptides (AMPs) represent a large family of molecules with the common ability to punch holes in cell membranes to alter their permeability. They play a fundamental role as infectious bacteria's defensive tools against host's immune system and as executors of endogenous machineries of regulated cell death in eukaryotic cells. Despite being highly divergent in primary sequence and 3D structure, specific folds of pore-forming domains have been conserved. In fact, pore formation is considered an ancient mechanism that takes place through a general multistep process involving: membrane partitioning and insertion, oligomerization and pore formation. However, different PFPs and AMPs assemble and form pores following different mechanisms that could end up either in the formation of protein-lined or protein-lipid pores. In this review, we analyze the current findings in the mechanism of action of different PFPs and AMPs that support a wide role of membrane pore formation in nature. We also provide the newest insights into the development of state-of-art techniques that have facilitated the characterization of membrane pores. To understand the physiological role of these peptides/proteins or develop clinical applications, it is essential to uncover the molecular mechanism of how they perforate membranes.
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Liu Y, Zhang Z, Wang F, Li DD, Li YZ. Identification of type VI secretion system toxic effectors using adaptors as markers. Comput Struct Biotechnol J 2020; 18:3723-3733. [PMID: 33304467 PMCID: PMC7714669 DOI: 10.1016/j.csbj.2020.11.003] [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: 08/27/2020] [Revised: 10/31/2020] [Accepted: 11/02/2020] [Indexed: 12/18/2022] Open
Abstract
Each class of adaptors can be used as an effective marker to identify T6SS effectors. The PRK06147 homolog may be a novel adaptor. 1356 putative toxic effectors related to adaptors from 92 families were identified.
Toxic effectors secreted by the type VI secretion system (T6SS) facilitate interbacterial warfare, as well as pathogenesis toward humans, animals and plants. However, systematically predicting T6SS effectors remains challenging due to their sequence and functional diversity. In this study, we systematically identified putative T6SS toxic effectors in prokaryotic genomes on the basis of the observation that genes encoding adaptor proteins and genes encoding cognate effector proteins are generally adjacent in the genome. Adaptor proteins are mediators that help to load their cognate effectors onto the T6SS spike complex. The contextual genes of the known adaptor proteins (DUF1795, DUF2169 or DUF4123) all exhibited a high proportion of encoding T6SS spike complex protein (VgrG or PAAR) and effector proteins. On the basis of the genomic context, we found that PRK06147 might be a novel adaptor protein. These four adaptors are widely distributed among the bacterial genomes. From neighbors of 5297 adaptor genes, we identified 1356 putative effector genes from 92 different families, and two-thirds were currently annotated as hypothetical proteins or as having unknown functions. Our results indicate that each class of adaptors can be used as an effective marker to identify T6SS toxic effectors, moreover, this approach can promote the discovery of new effectors.
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Affiliation(s)
- Ya Liu
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Zheng Zhang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China.,Suzhou Research Institute, Shandong University, Suzhou 215123, China
| | - Feng Wang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Dan-Dan Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Yue-Zhong Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China
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A toxin complex protein from Photorhabdus akhurstii conferred oral insecticidal activity against Galleria mellonella by targeting the midgut epithelium. Microbiol Res 2020; 242:126642. [PMID: 33191102 DOI: 10.1016/j.micres.2020.126642] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/16/2020] [Accepted: 10/30/2020] [Indexed: 02/08/2023]
Abstract
The nematode-bacterium pair Heterorhabditis indica-Photorhabdus akhurstii is a malleable model system to investigate mutualistic relations. A number of toxins produced by P. akhurstii allow the bacterium to kill the insect host. However, a few of these heterologously expressed toxins are orally active against different insects which possibly caused neglected attention to Photorhabdus toxins compared to Bt (Bacillus thuringiensis). In the current study, a functional subunit of orally active toxin complex (Tc) protein, TcaB (63 kDa), isolated from two strains of P. akhurstii namely IARI-SGHR2 and IARI-SGMS1, was tested for biological activity against Galleria mellonella. A force feeding-based administration of the toxin translated into LD50 values of 45.63-58.90 ng/g which was even lower compared to injection LD50 values (51.48-64.30 ng/g) at 48 h after inoculation. An oral uptake of 500 ng toxin caused extensive gut damage in G. mellonella during 6-24 h incubation period coupled with a gradual disruption of gut integrity leading to escape of TcaB into the hemocoel. This finding was supported by the cytotoxic and immune-stimulatory effect of TcaB in the insect hemocoel at 6-24 h after force feeding. The circulatory hemocyte numbers and cell viability was markedly reduced to 0.66-0.68 × 106 ml-1 and 49-52 %, respectively, in TcaB force fed insect at 24 h, compared to control (2.55 × 106 ml-1; 100 %). The hemolymph phenoloxidase (PO) activity was elevated by 10.2-fold in force fed larvae than control at 24 h. An in silico docking study revealed that TcaB putatively interacts with a number of G. mellonella receptor proteins in order to become a gut-active toxin. Present research reinforces the potential of gut-active Photorhabdus toxins for their inclusion in sustainable insect management tactics and strengthens the existing Bt-dominated management repository.
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da Silva WJ, Pilz-Júnior HL, Heermann R, da Silva OS. The great potential of entomopathogenic bacteria Xenorhabdus and Photorhabdus for mosquito control: a review. Parasit Vectors 2020; 13:376. [PMID: 32727530 PMCID: PMC7391577 DOI: 10.1186/s13071-020-04236-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 07/15/2020] [Indexed: 12/13/2022] Open
Abstract
The control of insects of medical importance, such as Aedes aegypti and Aedes albopictus are still the only effective way to prevent the transmission of diseases, such as dengue, chikungunya and Zika. Their control is performed mainly using chemical products; however, they often have low specificity to non-target organisms, including humans. Also, studies have reported resistance to the most commonly used insecticides, such as the organophosphate and pyrethroids. Biological control is an ecological and sustainable method since it has a slow rate of insect resistance development. Bacterial species of the genera Xenorhabdus and Photorhabdus have been the target of several research groups worldwide, aiming at their use in agricultural, pharmaceutical and industrial products. This review highlights articles referring to the use of Xenorhabdus and Photorhabdus for insects and especially for mosquito control proposing future ways for their biotechnological applicability. Approximately 24 species of Xenorhabdus and five species of Photorhabdus have been described to have insecticidal properties. These studies have shown genes that are capable of encoding low molecular weight proteins, secondary toxin complexes and metabolites with insecticide activities, as well as antibiotic, fungicidal and antiparasitic molecules. In addition, several species of Xenorhabdus and Photorhabdus showed insecticidal properties against mosquitoes. Therefore, these biological agents can be used in new control methods, and must be, urgently considered in short term, in studies and applications, especially in mosquito control.![]()
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Affiliation(s)
- Wellington Junior da Silva
- Department of Microbiology, Immunology and Parasitology, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Rua Sarmento Leite 500, Porto Alegre, RS, 90050-170, Brazil
| | - Harry Luiz Pilz-Júnior
- Department of Microbiology, Immunology and Parasitology, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Rua Sarmento Leite 500, Porto Alegre, RS, 90050-170, Brazil
| | - Ralf Heermann
- Institut für Molekulare Physiologie, Mikrobiologie und Weinforschung, Johannes-Gutenberg-Universität Mainz, Johann-Joachim-Becher-Weg 13, 55128, Mainz, Germany.
| | - Onilda Santos da Silva
- Department of Microbiology, Immunology and Parasitology, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Rua Sarmento Leite 500, Porto Alegre, RS, 90050-170, Brazil.
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Roderer D, Bröcker F, Sitsel O, Kaplonek P, Leidreiter F, Seeberger PH, Raunser S. Glycan-dependent cell adhesion mechanism of Tc toxins. Nat Commun 2020; 11:2694. [PMID: 32483155 PMCID: PMC7264150 DOI: 10.1038/s41467-020-16536-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 05/11/2020] [Indexed: 01/19/2023] Open
Abstract
Toxin complex (Tc) toxins are virulence factors of pathogenic bacteria. Tcs are composed of three subunits: TcA, TcB and TcC. TcA facilitates receptor-toxin interaction and membrane permeation, TcB and TcC form a toxin-encapsulating cocoon. While the mechanisms of holotoxin assembly and pore formation have been described, little is known about receptor binding of TcAs. Here, we identify heparins/heparan sulfates and Lewis antigens as receptors for different TcAs from insect and human pathogens. Glycan array screening reveals that all tested TcAs bind negatively charged heparins. Cryo-EM structures of Morganella morganii TcdA4 and Xenorhabdus nematophila XptA1 reveal that heparins/heparan sulfates unexpectedly bind to different regions of the shell domain, including receptor-binding domains. In addition, Photorhabdus luminescens TcdA1 binds to Lewis antigens with micromolar affinity. Here, the glycan interacts with the receptor-binding domain D of the toxin. Our results suggest a glycan dependent association mechanism of Tc toxins on the host cell surface.
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Affiliation(s)
- Daniel Roderer
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany
| | - Felix Bröcker
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, 14476, Potsdam, Germany
- Vaxxilon Deutschland GmbH, 12489, Berlin, Germany
| | - Oleg Sitsel
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany
| | - Paulina Kaplonek
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, 14476, Potsdam, Germany
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, 02139, USA
| | - Franziska Leidreiter
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, 69120, Heidelberg, Germany
| | - Peter H Seeberger
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, 14476, Potsdam, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany.
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44
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Li J, Xie Y, Cornelius S, Jiang X, Sando R, Kordon SP, Pan M, Leon K, Südhof TC, Zhao M, Araç D. Alternative splicing controls teneurin-latrophilin interaction and synapse specificity by a shape-shifting mechanism. Nat Commun 2020; 11:2140. [PMID: 32358586 PMCID: PMC7195488 DOI: 10.1038/s41467-020-16029-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 04/06/2020] [Indexed: 02/07/2023] Open
Abstract
The trans-synaptic interaction of the cell-adhesion molecules teneurins (TENs) with latrophilins (LPHNs/ADGRLs) promotes excitatory synapse formation when LPHNs simultaneously interact with FLRTs. Insertion of a short alternatively-spliced region within TENs abolishes the TEN-LPHN interaction and switches TEN function to specify inhibitory synapses. How alternative-splicing regulates TEN-LPHN interaction remains unclear. Here, we report the 2.9 Å resolution cryo-EM structure of the TEN2-LPHN3 complex, and describe the trimeric TEN2-LPHN3-FLRT3 complex. The structure reveals that the N-terminal lectin domain of LPHN3 binds to the TEN2 barrel at a site far away from the alternatively spliced region. Alternative-splicing regulates the TEN2-LPHN3 interaction by hindering access to the LPHN-binding surface rather than altering it. Strikingly, mutagenesis of the LPHN-binding surface of TEN2 abolishes the LPHN3 interaction and impairs excitatory but not inhibitory synapse formation. These results suggest that a multi-level coincident binding mechanism mediated by a cryptic adhesion complex between TENs and LPHNs regulates synapse specificity. The trans-synaptic interaction of the cell-adhesion molecules teneurins (TENs) with latrophilins (LPHNs) promotes excitatory synapse formation. Here authors report the high resolution cryo-EM structure of the TEN2-LPHN3 complex, describe the trimeric TEN2-LPHN3-FLRT3 complex and show how alternative-splicing regulates the TEN2-LPHN3 interaction.
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Affiliation(s)
- Jingxian Li
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA.,Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, 60637, USA
| | - Yuan Xie
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA
| | - Shaleeka Cornelius
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, 94305, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Xian Jiang
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, 94305, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Richard Sando
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, 94305, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Szymon P Kordon
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA.,Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, 60637, USA
| | - Man Pan
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA
| | - Katherine Leon
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA.,Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, 60637, USA
| | - Thomas C Südhof
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, 94305, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Minglei Zhao
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA.
| | - Demet Araç
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA. .,Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, 60637, USA.
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45
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Pei TT, Li H, Liang X, Wang ZH, Liu G, Wu LL, Kim H, Xie Z, Yu M, Lin S, Xu P, Dong TG. Intramolecular chaperone-mediated secretion of an Rhs effector toxin by a type VI secretion system. Nat Commun 2020; 11:1865. [PMID: 32313027 PMCID: PMC7170923 DOI: 10.1038/s41467-020-15774-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Accepted: 03/27/2020] [Indexed: 12/31/2022] Open
Abstract
Bacterial Rhs proteins containing toxic domains are often secreted by type VI secretion systems (T6SSs) through unclear mechanisms. Here, we show that the T6SS Rhs-family effector TseI of Aeromonas dhakensis is subject to self-cleavage at both the N- and the C-terminus, releasing the middle Rhs core and two VgrG-interacting domains (which we name VIRN and VIRC). VIRC is an endonuclease, and the immunity protein TsiI protects against VIRC toxicity through direct interaction. Proteolytic release of VIRC and VIRN is mediated, respectively, by an internal aspartic protease activity and by two conserved glutamic residues in the Rhs core. Mutations abolishing self-cleavage do not block secretion, but reduce TseI toxicity. Deletion of VIRN or the Rhs core abolishes secretion. TseI homologs from Pseudomonas syringae, P. aeruginosa, and Vibrio parahaemolyticus are also self-cleaved. VIRN and VIRC interact with protein VgrG1, while the Rhs core interacts with protein TecI. We propose that VIRN and the Rhs core act as T6SS intramolecular chaperones to facilitate toxin secretion and function.
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Affiliation(s)
- Tong-Tong Pei
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Hao Li
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Xiaoye Liang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China.,Department of Ecosystem and Public Health, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, T2N4Z6, Canada
| | - Zeng-Hang Wang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Guangfeng Liu
- National Center for Protein Science Shanghai, Shanghai Advanced Research Institute, Chinese Academy of Sciences, 201204, Shanghai, China
| | - Li-Li Wu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Haeun Kim
- Department of Ecosystem and Public Health, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, T2N4Z6, Canada
| | - Zhiping Xie
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Ming Yu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Shuangjun Lin
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Ping Xu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Tao G Dong
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China. .,Department of Ecosystem and Public Health, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, T2N4Z6, Canada.
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46
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Abstract
Different model systems have, over the years, contributed to our current understanding of the molecular mechanisms underpinning the various types of interaction between bacteria and their animal hosts. The genus
Photorhabdus
comprises Gram-negative insect pathogenic bacteria that are normally found as symbionts that colonize the gut of the infective juvenile stage of soil-dwelling nematodes from the family Heterorhabditis. The nematodes infect susceptible insects and release the bacteria into the insect haemolymph where the bacteria grow, resulting in the death of the insect. At this stage the nematodes feed on the bacterial biomass and, following several rounds of reproduction, the nematodes develop into infective juveniles that leave the insect cadaver in search of new hosts. Therefore
Photorhabdus
has three distinct and obligate roles to play during this life-cycle: (1)
Photorhabdus
must kill the insect host; (2)
Photorhabdus
must be capable of supporting nematode growth and development; and (3)
Photorhabdus
must be able to colonize the gut of the next generation of infective juveniles before they leave the insect cadaver. In this review I will discuss how genetic analysis has identified key genes involved in mediating, and regulating, the interaction between
Photorhabdus
and each of its invertebrate hosts. These studies have resulted in the characterization of several new families of toxins and a novel inter-kingdom signalling molecule and have also uncovered an important role for phase variation in the regulation of these different roles.
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Affiliation(s)
- David J Clarke
- School of Microbiology and APC Microbiome Ireland, University College Cork, Cork, Ireland
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47
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Abstract
The interactions between lipids and proteins are one of the most fundamental processes in living organisms, responsible for critical cellular events ranging from replication, cell division, signaling, and movement. Enabling the central coupling responsible for maintaining the functionality of the breadth of proteins, receptors, and enzymes that find their natural home in biological membranes, the fundamental mechanisms of recognition of protein for lipid, and vice versa, have been a focal point of biochemical and biophysical investigations for many decades. Complexes of lipids and proteins, such as the various lipoprotein factions, play central roles in the trafficking of important proteins, small molecules and metabolites and are often implicated in disease states. Recently an engineered lipoprotein particle, termed the nanodisc, a modified form of the human high density lipoprotein fraction, has served as a membrane mimetic for the investigation of membrane proteins and studies of lipid-protein interactions. In this review, we summarize the current knowledge regarding this self-assembling lipid-protein complex and provide examples for its utility in the investigation of a large number of biological systems.
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48
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Yamada T, Yoshida T, Kawamoto A, Mitsuoka K, Iwasaki K, Tsuge H. Cryo-EM structures reveal translocational unfolding in the clostridial binary iota toxin complex. Nat Struct Mol Biol 2020; 27:288-296. [PMID: 32123390 DOI: 10.1038/s41594-020-0388-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 01/17/2020] [Indexed: 11/09/2022]
Abstract
The iota toxin produced by Clostridium perfringens type E is a binary toxin comprising two independent polypeptides: Ia, an ADP-ribosyltransferase, and Ib, which is involved in cell binding and translocation of Ia across the cell membrane. Here we report cryo-EM structures of the translocation channel Ib-pore and its complex with Ia. The high-resolution Ib-pore structure demonstrates a similar structural framework to that of the catalytic ϕ-clamp of the anthrax protective antigen pore. However, the Ia-bound Ib-pore structure shows a unique binding mode of Ia: one Ia binds to the Ib-pore, and the Ia amino-terminal domain forms multiple weak interactions with two additional Ib-pore constriction sites. Furthermore, Ib-binding induces tilting and partial unfolding of the Ia N-terminal α-helix, permitting its extension to the ϕ-clamp gate. This new mechanism of N-terminal unfolding is crucial for protein translocation.
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Affiliation(s)
- Tomohito Yamada
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, Japan
| | - Toru Yoshida
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, Japan.,Institute for Protein Dynamics, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, Japan
| | - Akihiro Kawamoto
- Institute for Protein Research, Osaka University, Suita, Osaka, Japan
| | - Kaoru Mitsuoka
- Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Ibaraki, Osaka, Japan
| | - Kenji Iwasaki
- Institute for Protein Research, Osaka University, Suita, Osaka, Japan.,Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba, Japan
| | - Hideaki Tsuge
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, Japan. .,Institute for Protein Dynamics, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, Japan. .,Center for Molecular Research in Infectious Diseases, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, Japan.
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49
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Del Toro D, Carrasquero-Ordaz MA, Chu A, Ruff T, Shahin M, Jackson VA, Chavent M, Berbeira-Santana M, Seyit-Bremer G, Brignani S, Kaufmann R, Lowe E, Klein R, Seiradake E. Structural Basis of Teneurin-Latrophilin Interaction in Repulsive Guidance of Migrating Neurons. Cell 2020; 180:323-339.e19. [PMID: 31928845 PMCID: PMC6978801 DOI: 10.1016/j.cell.2019.12.014] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 10/15/2019] [Accepted: 12/11/2019] [Indexed: 02/07/2023]
Abstract
Teneurins are ancient metazoan cell adhesion receptors that control brain development and neuronal wiring in higher animals. The extracellular C terminus binds the adhesion GPCR Latrophilin, forming a trans-cellular complex with synaptogenic functions. However, Teneurins, Latrophilins, and FLRT proteins are also expressed during murine cortical cell migration at earlier developmental stages. Here, we present crystal structures of Teneurin-Latrophilin complexes that reveal how the lectin and olfactomedin domains of Latrophilin bind across a spiraling beta-barrel domain of Teneurin, the YD shell. We couple structure-based protein engineering to biophysical analysis, cell migration assays, and in utero electroporation experiments to probe the importance of the interaction in cortical neuron migration. We show that binding of Latrophilins to Teneurins and FLRTs directs the migration of neurons using a contact repulsion-dependent mechanism. The effect is observed with cell bodies and small neurites rather than their processes. The results exemplify how a structure-encoded synaptogenic protein complex is also used for repulsive cell guidance. Crystal structures reveal binding site for Latrophilin on the Teneurin YD shell A ternary Latrophilin-Teneurin-FLRT complex forms in vitro and in vivo Latrophilin controls cortical migration by binding to Teneurins and FLRTs Latrophilin elicits repulsion of cortical cell bodies/small neurites but not axons
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Affiliation(s)
- Daniel Del Toro
- Max Planck Institute of Neurobiology, Am Klopferspitz 18, Martinsried 82152, Germany; Department of Biological Sciences, Institute of Neurosciences, IDIBAPS, CIBERNED, University of Barcelona, Barcelona, Spain
| | | | - Amy Chu
- Department of Biochemistry, Oxford University, Oxford OX1 3QU, UK
| | - Tobias Ruff
- Max Planck Institute of Neurobiology, Am Klopferspitz 18, Martinsried 82152, Germany
| | - Meriam Shahin
- Department of Biochemistry, Oxford University, Oxford OX1 3QU, UK
| | - Verity A Jackson
- Department of Biochemistry, Oxford University, Oxford OX1 3QU, UK
| | | | | | - Goenuel Seyit-Bremer
- Max Planck Institute of Neurobiology, Am Klopferspitz 18, Martinsried 82152, Germany
| | - Sara Brignani
- Max Planck Institute of Neurobiology, Am Klopferspitz 18, Martinsried 82152, Germany
| | - Rainer Kaufmann
- Center for Structural Systems Biology, University of Hamburg, Hamburg 22607, Germany; Department of Physics, University of Hamburg, Hamburg 20355, Germany
| | - Edward Lowe
- Department of Biochemistry, Oxford University, Oxford OX1 3QU, UK
| | - Rüdiger Klein
- Max Planck Institute of Neurobiology, Am Klopferspitz 18, Martinsried 82152, Germany.
| | - Elena Seiradake
- Department of Biochemistry, Oxford University, Oxford OX1 3QU, UK.
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50
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Towards the application of Tc toxins as a universal protein translocation system. Nat Commun 2019; 10:5263. [PMID: 31748551 PMCID: PMC6868009 DOI: 10.1038/s41467-019-13253-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 10/28/2019] [Indexed: 11/25/2022] Open
Abstract
Tc toxins are bacterial protein complexes that inject cytotoxic enzymes into target cells using a syringe-like mechanism. Tc toxins are composed of a membrane translocator and a cocoon that encapsulates a toxic enzyme. The toxic enzyme varies between Tc toxins from different species and is not conserved. Here, we investigate whether the toxic enzyme can be replaced by other small proteins of different origin and properties, namely Cdc42, herpes simplex virus ICP47, Arabidopsis thaliana iLOV, Escherichia coli DHFR, Ras-binding domain of CRAF kinase, and TEV protease. Using a combination of electron microscopy, X-ray crystallography and in vitro translocation assays, we demonstrate that it is possible to turn Tc toxins into customizable molecular syringes for delivering proteins of interest across membranes. We also infer the guidelines that protein cargos must obey in terms of size, charge, and fold in order to apply Tc toxins as a universal protein translocation system. Tc toxins are a major class of bacterial toxin translocation systems that inject toxic enzymes into target cells. Here the authors present functional and structural data showing that the toxic enzyme can be replaced by other small proteins and identify prerequisites required for successful translocation, which could facilitate the development of functional Tc-based protein injection devices.
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