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Abrahamsen HL, Sanford TC, Collamore CE, Johnstone BA, Coyne MJ, García-Bayona L, Christie MP, Evans JC, Farrand AJ, Flores K, Morton CJ, Parker MW, Comstock LE, Tweten RK. Distant relatives of a eukaryotic cell-specific toxin family evolved a complement-like mechanism to kill bacteria. Nat Commun 2024; 15:5028. [PMID: 38866748 PMCID: PMC11169675 DOI: 10.1038/s41467-024-49103-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 05/22/2024] [Indexed: 06/14/2024] Open
Abstract
Cholesterol-dependent cytolysins (CDCs) comprise a large family of pore-forming toxins produced by Gram-positive bacteria, which are used to attack eukaryotic cells. Here, we functionally characterize a family of 2-component CDC-like (CDCL) toxins produced by the Gram-negative Bacteroidota that form pores by a mechanism only described for the mammalian complement membrane attack complex (MAC). We further show that the Bacteroides CDCLs are not eukaryotic cell toxins like the CDCs, but instead bind to and are proteolytically activated on the surface of closely related species, resulting in pore formation and cell death. The CDCL-producing Bacteroides is protected from the effects of its own CDCL by the presence of a surface lipoprotein that blocks CDCL pore formation. These studies suggest a prevalent mode of bacterial antagonism by a family of two-component CDCLs that function like mammalian MAC and that are wide-spread in the gut microbiota of diverse human populations.
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Affiliation(s)
- Hunter L Abrahamsen
- Department of Microbiology & Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Tristan C Sanford
- Department of Microbiology & Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Casie E Collamore
- Department of Microbiology & Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Bronte A Johnstone
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Michael J Coyne
- Duchossois Family Institute and Department of Microbiology, University of Chicago, Chicago, IL, USA
| | - Leonor García-Bayona
- Duchossois Family Institute and Department of Microbiology, University of Chicago, Chicago, IL, USA
| | - Michelle P Christie
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Jordan C Evans
- Department of Microbiology & Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Wheeler Bio, Oklahoma City, OK, 73104, USA
| | - Allison J Farrand
- Department of Microbiology & Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Wheeler Bio, Oklahoma City, OK, 73104, USA
| | - Katia Flores
- Duchossois Family Institute and Department of Microbiology, University of Chicago, Chicago, IL, USA
| | - Craig J Morton
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia
- CSIRO Biomedical Manufacturing Program, Clayton, VIC, 3168, Australia
| | - Michael W Parker
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia.
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia.
- Australian Cancer Research Foundation Rational Drug Discovery Centre, St Vincent's Institute of Medical Research, Fitzroy, VIC, 2065, Australia.
| | - Laurie E Comstock
- Duchossois Family Institute and Department of Microbiology, University of Chicago, Chicago, IL, USA.
| | - Rodney K Tweten
- Department of Microbiology & Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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Marini G, Poland B, Leininger C, Lukoyanova N, Spielbauer D, Barry JK, Altier D, Lum A, Scolaro E, Ortega CP, Yalpani N, Sandahl G, Mabry T, Klever J, Nowatzki T, Zhao JZ, Sethi A, Kassa A, Crane V, Lu AL, Nelson ME, Eswar N, Topf M, Saibil HR. Structural journey of an insecticidal protein against western corn rootworm. Nat Commun 2023; 14:4171. [PMID: 37443175 PMCID: PMC10344926 DOI: 10.1038/s41467-023-39891-7] [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: 01/12/2023] [Accepted: 06/28/2023] [Indexed: 07/15/2023] Open
Abstract
The broad adoption of transgenic crops has revolutionized agriculture. However, resistance to insecticidal proteins by agricultural pests poses a continuous challenge to maintaining crop productivity and new proteins are urgently needed to replace those utilized for existing transgenic traits. We identified an insecticidal membrane attack complex/perforin (MACPF) protein, Mpf2Ba1, with strong activity against the devastating coleopteran pest western corn rootworm (WCR) and a novel site of action. Using an integrative structural biology approach, we determined monomeric, pre-pore and pore structures, revealing changes between structural states at high resolution. We discovered an assembly inhibition mechanism, a molecular switch that activates pre-pore oligomerization upon gut fluid incubation and solved the highest resolution MACPF pore structure to-date. Our findings demonstrate not only the utility of Mpf2Ba1 in the development of biotechnology solutions for protecting maize from WCR to promote food security, but also uncover previously unknown mechanistic principles of bacterial MACPF assembly.
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Affiliation(s)
- Guendalina Marini
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet St, London, WC1E 7HX, UK
- Centre for Structural Systems Biology (CSSB), Leibniz-Institut für Virologie (LIV), Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Brad Poland
- Corteva Agriscience, Johnston, IA, 50131, USA
| | - Chris Leininger
- Corteva Agriscience, Johnston, IA, 50131, USA
- Syngenta, Research Triangle Park, NC, 27709, USA
| | - Natalya Lukoyanova
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet St, London, WC1E 7HX, UK
| | | | | | - Dan Altier
- Corteva Agriscience, Johnston, IA, 50131, USA
| | - Amy Lum
- Corteva Agriscience, Johnston, IA, 50131, USA
- Willow Biosciences, 319 N Bernardo Ave #4, Mountain View, CA, 94043, USA
| | | | - Claudia Pérez Ortega
- Corteva Agriscience, Johnston, IA, 50131, USA
- Hologic, Inc., 250 Campus Drive, Marlborough, MA, 01752, USA
| | - Nasser Yalpani
- Corteva Agriscience, Johnston, IA, 50131, USA
- Dept. of Biology, University of British Columbia Okanagan, 3187 University Way, Kelowna, BC, V1V 1V7, Canada
| | | | - Tim Mabry
- Corteva Agriscience, Ivesdale, IL, 61851, USA
| | | | | | | | - Amit Sethi
- Corteva Agriscience, Johnston, IA, 50131, USA
| | - Adane Kassa
- Corteva Agriscience, Johnston, IA, 50131, USA
| | | | - Albert L Lu
- Corteva Agriscience, Johnston, IA, 50131, USA
| | | | | | - Maya Topf
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet St, London, WC1E 7HX, UK.
- Centre for Structural Systems Biology (CSSB), Leibniz-Institut für Virologie (LIV), Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany.
| | - Helen R Saibil
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet St, London, WC1E 7HX, UK.
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Johnstone BA, Joseph R, Christie MP, Morton CJ, McGuiness C, Walsh JC, Böcking T, Tweten RK, Parker MW. Cholesterol-dependent cytolysins: The outstanding questions. IUBMB Life 2022; 74:1169-1179. [PMID: 35836358 PMCID: PMC9712165 DOI: 10.1002/iub.2661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 06/23/2022] [Indexed: 11/06/2022]
Abstract
The cholesterol-dependent cytolysins (CDCs) are a major family of bacterial pore-forming proteins secreted as virulence factors by Gram-positive bacterial species. CDCs are produced as soluble, monomeric proteins that bind specifically to cholesterol-rich membranes, where they oligomerize into ring-shaped pores of more than 30 monomers. Understanding the details of the steps the toxin undergoes in converting from monomer to a membrane-spanning pore is a continuing challenge. In this review we summarize what we know about CDCs and highlight the remaining outstanding questions that require answers to obtain a complete picture of how these toxins kill cells.
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Affiliation(s)
- Bronte A Johnstone
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Riya Joseph
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Michelle P Christie
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Craig J Morton
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Conall McGuiness
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - James C Walsh
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Till Böcking
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Rodney K Tweten
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Michael W Parker
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
- Australian Cancer Research Foundation Rational Drug Discovery Centre, St Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia
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Gamage RS, Smith BD. Spontaneous Transfer of Indocyanine Green from Liposomes to Albumin Is Inhibited by the Antioxidant α-Tocopherol. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:11950-11961. [PMID: 36126324 PMCID: PMC9897306 DOI: 10.1021/acs.langmuir.2c01715] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Indocyanine Green (ICG) is a clinically approved organic dye with near-infrared absorption and fluorescence. Over the years, many efforts to improve the photophysical and pharmacokinetic properties of ICG have investigated numerous nanoparticle formulations, especially liposomes with membrane-embedded ICG. A series of systematic absorption and fluorescence experiments, including FRET experiments using ICG as a fluorescence energy acceptor, found that ICG transfers spontaneously from liposomes to albumin protein residing in the external solution with a half-life of ∼10 min at 37 °C. Moreover, transfer of ICG from liposome membranes to external albumin reduces light-activated leakage from thermosensitive liposomes with membrane-embedded ICG. A survey of lipophilic liposome additives discovered that the presence of clinically approved antioxidant, α-tocopherol, greatly increases ICG retention in the liposomes (presumably by forming favorable aromatic stacking interactions), inhibits ICG photobleaching and prevents albumin-induced reduction of light-triggered liposome leakage. This new insight will help researchers with the specific task of optimizing ICG-containing liposomes for fluorescence imaging or phototherapeutics. More broadly, the results suggest a broader design concept concerning light triggered liposome leakage, that is, proximity of the light absorbing dye to the bilayer membrane is a critical design feature that impacts the extent of liposome leakage.
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McGuinness C, Walsh JC, Bayly-Jones C, Dunstone MA, Christie MP, Morton CJ, Parker MW, Böcking T. Single-molecule analysis of the entire perfringolysin O pore formation pathway. eLife 2022; 11:74901. [PMID: 36000711 PMCID: PMC9457685 DOI: 10.7554/elife.74901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 08/16/2022] [Indexed: 11/20/2022] Open
Abstract
The cholesterol-dependent cytolysin perfringolysin O (PFO) is secreted by Clostridium perfringens as a bacterial virulence factor able to form giant ring-shaped pores that perforate and ultimately lyse mammalian cell membranes. To resolve the kinetics of all steps in the assembly pathway, we have used single-molecule fluorescence imaging to follow the dynamics of PFO on dye-loaded liposomes that lead to opening of a pore and release of the encapsulated dye. Formation of a long-lived membrane-bound PFO dimer nucleates the growth of an irreversible oligomer. The growing oligomer can insert into the membrane and open a pore at stoichiometries ranging from tetramers to full rings (~35 mers), whereby the rate of insertion increases linearly with the number of subunits. Oligomers that insert before the ring is complete continue to grow by monomer addition post insertion. Overall, our observations suggest that PFO membrane insertion is kinetically controlled.
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Affiliation(s)
- Conall McGuinness
- EMBL Australia Node in Single Molecule Science, University of New South Wales, Sydney, Australia
| | - James C Walsh
- EMBL Australia Node in Single Molecule Science, University of New South Wales, Sydney, Australia
| | - Charles Bayly-Jones
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
| | - Michelle A Dunstone
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
| | - Michelle P Christie
- Department of Biochemistry and Pharmacology, University of Melbourne, Melbourne, Australia
| | - Craig J Morton
- Department of Biochemistry and Pharmacology, University of Melbourne, Melbourne, Australia
| | - Michael W Parker
- Australian Cancer Research Foundation Rational Drug Discovery Centre, St Vincents Institute of Medical Research, Fitzroy, Australia
| | - Till Böcking
- EMBL Australia Node in Single Molecule Science, University of New South Wales, Sydney, Australia
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Lipids modulate the BH3-independent membrane targeting and activation of BAX and Bcl-xL. Proc Natl Acad Sci U S A 2021; 118:2025834118. [PMID: 34493661 DOI: 10.1073/pnas.2025834118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 07/21/2021] [Indexed: 12/13/2022] Open
Abstract
Regulation of apoptosis is tightly linked with the targeting of numerous Bcl-2 proteins to the mitochondrial outer membrane (MOM), where their activation or inhibition dictates cell death or survival. According to the traditional view of apoptotic regulation, BH3-effector proteins are indispensable for the cytosol-to-MOM targeting and activation of proapoptotic and antiapoptotic members of the Bcl-2 protein family. This view is challenged by recent studies showing that these processes can occur in cells lacking BH3 effectors by as yet to be determined mechanism(s). Here, we exploit a model membrane system that recapitulates key features of MOM to demonstrate that the proapoptotic Bcl-2 protein BAX and antiapoptotic Bcl-xL have an inherent ability to interact with membranes in the absence of BH3 effectors, but only in the presence of cellular concentrations of Mg2+/Ca2+ Under these conditions, BAX and Bcl-xL are selectively targeted to membranes, refolded, and activated in the presence of anionic lipids especially the mitochondrial-specific lipid cardiolipin. These results provide a mechanistic explanation for the mitochondrial targeting and activation of Bcl-2 proteins in cells lacking BH3 effectors. At cytosolic Mg2+ levels, the BH3-independent activation of BAX could provide localized amplification of apoptotic signaling at regions enriched in cardiolipin (e.g., contact sites between MOM and mitochondrial inner membrane). Increases in MOM cardiolipin, as well as cytosolic [Ca2+] during apoptosis could further contribute to its MOM targeting and activity. Meanwhile, the BH3-independent targeting and activation of Bcl-xL to the MOM is expected to counter the action of proapoptotic BAX, thereby preventing premature commitment to apoptosis.
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Evans JC, Tweten RK. How protein engineering has revealed the molecular mechanisms of pore-forming toxins. Methods Enzymol 2021; 649:47-70. [PMID: 33712197 DOI: 10.1016/bs.mie.2021.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Pore-forming proteins are found in prokaryotes, vertebrates, and invertebrates, and when involved in pathogenic processes they are classified as pore-forming toxins (PFTs). The use of gene engineering methods in combination with the information provided by the high-resolution crystal structures of the PFTs have allowed investigators to gain a deep understanding of their pore-forming mechanisms. In this chapter, we discuss how protein engineering has helped us and others to reveal the molecular mechanisms of pore formation by prokaryotic PFTs with an emphasis on our experiences with the cholesterol-dependent cytolysins (CDCs).
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Affiliation(s)
- Jordan C Evans
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Rodney K Tweten
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.
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Abstract
The cholesterol-dependent cytolysins’ pore-forming mechanism relies on the ability to sense the completion of the oligomeric prepore structure and initiate the insertion of the β-barrel pore from the assembled prepore structure. These studies show that a conserved motif is an important component of the sensor that triggers the prepore-to-pore transition and that it is conserved in a large family of previously unidentified CDC-like proteins, the genes for which are present in a vast array of microbial species that span most terrestrial environments, as well as most animal and human microbiomes. These studies establish the foundation for future investigations that will probe the contribution of this large family of CDC-like proteins to microbial survival and human disease. The cholesterol-dependent cytolysins (CDCs) are bacterial, β-barrel, pore-forming toxins. A central enigma of the pore-forming mechanism is how completion of the prepore is sensed to initiate its conversion to the pore. We identified a motif that is conserved between the CDCs and a diverse family of nearly 300 uncharacterized proteins present in over 220 species that span at least 10 bacterial and 2 eukaryotic phyla. Except for this motif, these proteins exhibit little similarity to the CDCs at the primary structure level. Studies herein show this motif is a critical component of the sensor that initiates the prepore-to-pore transition in the CDCs. We further show by crystallography, single particle analysis, and biochemical studies of one of these CDC-like (CDCL) proteins from Elizabethkingia anophelis, a commensal of the malarial mosquito midgut, that a high degree of structural similarity exists between the CDC and CDCL monomer structures and both form large oligomeric pore complexes. Furthermore, the conserved motif in the E. anophelis CDCL crystal structure occupies a nearly identical position and makes similar contacts to those observed in the structure of the archetype CDC, perfringolysin O (PFO). This suggests a common function in the CDCs and CDCLs and may explain why only this motif is conserved in the CDCLs. Hence, these studies identify a critical component of the sensor involved in initiating the prepore-to-pore transition in the CDCs, which is conserved in a large and diverse group of distant relatives of the CDCs.
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Mondal AK, Chattopadhyay K. Taking Toll on Membranes: Curious Cases of Bacterial β-Barrel Pore-Forming Toxins. Biochemistry 2019; 59:163-170. [DOI: 10.1021/acs.biochem.9b00783] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Anish Kumar Mondal
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali, Punjab 140306, India
| | - Kausik Chattopadhyay
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali, Punjab 140306, India
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