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Sevdalis SE, Varney KM, Cook ME, Gillespie JJ, Pozharski E, Weber DJ. Structural and Functional Insights into the Delivery Systems of Bacillus and Clostridial Binary Toxins. Toxins (Basel) 2024; 16:330. [PMID: 39195740 PMCID: PMC11359772 DOI: 10.3390/toxins16080330] [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: 06/07/2024] [Revised: 07/04/2024] [Accepted: 07/19/2024] [Indexed: 08/29/2024] Open
Abstract
Pathogenic Bacillus and clostridial (i.e., Clostridium and Clostridioides) bacteria express a diverse repertoire of effector proteins to promote disease. This includes production of binary toxins, which enter host epithelial cells and seriously damage the intestinal tracts of insects, animals, and humans. In particular, binary toxins form an AB-type complex composed of a catalytic subunit that is toxic (A) and an oligomeric cell-binding and delivery subunit (B), where upon delivery of A into the cytoplasm of the host cell it catalytically ADP-ribosylates actin and rapidly induces host cell death. In this review, binary toxins expressed by Bacillus thuringiensis, Clostridioides difficile, and Clostridium perfringens will be discussed, with particular focus placed upon the structural elucidations of their respective B subunits and how these findings help to deconvolute how toxic enzyme delivery into target host cells is achieved by these deadly bacteria.
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Affiliation(s)
- Spiridon E. Sevdalis
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (K.M.V.); (M.E.C.); (E.P.)
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Kristen M. Varney
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (K.M.V.); (M.E.C.); (E.P.)
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Mary E. Cook
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (K.M.V.); (M.E.C.); (E.P.)
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Joseph J. Gillespie
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA;
| | - Edwin Pozharski
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (K.M.V.); (M.E.C.); (E.P.)
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - David J. Weber
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (K.M.V.); (M.E.C.); (E.P.)
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Tessier E, Cheutin L, Garnier A, Vigne C, Tournier JN, Rougeaux C. Early Circulating Edema Factor in Inhalational Anthrax Infection: Does It Matter? Microorganisms 2024; 12:308. [PMID: 38399712 PMCID: PMC10891819 DOI: 10.3390/microorganisms12020308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/22/2024] [Accepted: 01/26/2024] [Indexed: 02/25/2024] Open
Abstract
Anthrax toxins are critical virulence factors of Bacillus anthracis and Bacillus cereus strains that cause anthrax-like disease, composed of a common binding factor, the protective antigen (PA), and two enzymatic proteins, lethal factor (LF) and edema factor (EF). While PA is required for endocytosis and activity of EF and LF, several studies showed that these enzymatic factors disseminate within the body in the absence of PA after intranasal infection. In an effort to understand the impact of EF in the absence of PA, we used a fluorescent EF chimera to facilitate the study of endocytosis in different cell lines. Unexpectedly, EF was found inside cells in the absence of PA and showed a pole-dependent endocytosis. However, looking at enzymatic activity, PA was still required for EF to induce an increase in intracellular cAMP levels. Interestingly, the sequential delivery of EF and then PA rescued the rise in cAMP levels, indicating that PA and EF may functionally associate during intracellular trafficking, as well as it did at the cell surface. Our data shed new light on EF trafficking and the potential location of PA and EF association for optimal cytosolic delivery.
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Affiliation(s)
- Emilie Tessier
- Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, 91220 Brétigny-sur-Orge, France (C.R.)
| | - Laurence Cheutin
- Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, 91220 Brétigny-sur-Orge, France (C.R.)
| | - Annabelle Garnier
- Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, 91220 Brétigny-sur-Orge, France (C.R.)
| | - Clarisse Vigne
- Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, 91220 Brétigny-sur-Orge, France (C.R.)
| | - Jean-Nicolas Tournier
- Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, 91220 Brétigny-sur-Orge, France (C.R.)
- Institut Pasteur, 75015 Paris, France
| | - Clémence Rougeaux
- Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, 91220 Brétigny-sur-Orge, France (C.R.)
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Abeyawardhane DL, Sevdalis SE, Adipietro KA, Godoy-Ruiz R, Varney KM, Nawaz IF, Spittel AX, Rustandi RR, Silin VI, des Georges A, Pozharski E, Weber DJ. Membrane binding and pore formation is Ca 2+ -dependent for the Clostridioides difficile binary toxin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.18.553786. [PMID: 37645845 PMCID: PMC10462154 DOI: 10.1101/2023.08.18.553786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The C. difficile binary toxin (CDT) enters host cells via endosomal delivery like many other 'AB'-type binary toxins. In this study, the cell-binding component of CDT, termed CDTb, was found to bind and form pores in lipid bilayers upon depleting free Ca 2+ ion concentrations, and not by lowering pH, as found for other binary toxins (i.e., anthrax). Cryoelectron microscopy, nuclear magnetic resonance spectroscopy, surface plasmon resonance, electrochemical impedance spectroscopy, CDT toxicity studies, and site directed mutagenesis show that dissociation of Ca 2+ from a single site in receptor binding domain 1 (RBD1) of CDTb is consistent with a molecular mechanism in which Ca 2+ dissociation from RBD1 induces a "trigger" via conformational exchange that enables CDTb to bind and form pores in endosomal membrane bilayers as free Ca 2+ concentrations decrease during CDT endosomal delivery.
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Mondal AK, Lata K, Singh M, Chatterjee S, Chauhan A, Puravankara S, Chattopadhyay K. Cryo-EM elucidates mechanism of action of bacterial pore-forming toxins. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:184013. [PMID: 35908609 DOI: 10.1016/j.bbamem.2022.184013] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/05/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
Pore-forming toxins (PFTs) rupture plasma membranes and kill target cells. PFTs are secreted as soluble monomers that undergo drastic structural rearrangements upon interacting with the target membrane and generate transmembrane oligomeric pores. A detailed understanding of the molecular mechanisms of the pore-formation process remains unclear due to limited structural insights regarding the transmembrane oligomeric pore states of the PFTs. However, recent advances in the field of cryo-electron microscopy (cryo-EM) have led to the high-resolution structure determination of the oligomeric pore forms of diverse PFTs. Here, we discuss the pore-forming mechanisms of various PFTs, specifically the mechanistic details contributed by the cryo-EM-based structural studies.
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Affiliation(s)
- Anish Kumar Mondal
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Kusum Lata
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Mahendra Singh
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Shamaita Chatterjee
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Aakanksha Chauhan
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Sindhoora Puravankara
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Kausik Chattopadhyay
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India.
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Anwar MU, Sergeeva OA, Abrami L, Mesquita FS, Lukonin I, Amen T, Chuat A, Capolupo L, Liberali P, D'Angelo G, van der Goot FG. ER-Golgi-localized proteins TMED2 and TMED10 control the formation of plasma membrane lipid nanodomains. Dev Cell 2022; 57:2334-2346.e8. [PMID: 36174556 DOI: 10.1016/j.devcel.2022.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/24/2022] [Accepted: 09/08/2022] [Indexed: 11/03/2022]
Abstract
To promote infections, pathogens exploit host cell machineries such as structural elements of the plasma membrane. Studying these interactions and identifying molecular players are ideal for gaining insights into the fundamental biology of the host cell. Here, we used the anthrax toxin to screen a library of 1,500 regulatory, cell-surface, and membrane trafficking genes for their involvement in the intoxication process. We found that endoplasmic reticulum (ER)-Golgi-localized proteins TMED2 and TMED10 are required for toxin oligomerization at the plasma membrane of human cells, an essential step dependent on localization to cholesterol-rich lipid nanodomains. Biochemical, morphological, and mechanistic analyses showed that TMED2 and TMED10 are essential components of a supercomplex that operates the exchange of both cholesterol and ceramides at ER-Golgi membrane contact sites. Overall, this study of anthrax intoxication led to the discovery that lipid compositional remodeling at ER-Golgi interfaces fully controls the formation of functional membrane nanodomains at the cell surface.
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Affiliation(s)
- Muhammad U Anwar
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Oksana A Sergeeva
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Laurence Abrami
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Francisco S Mesquita
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Ilya Lukonin
- Friedrich Miescher Institute for Biomedical Research (FMI), 4058 Basel, Switzerland; University of Basel, 4056 Basel, Switzerland
| | - Triana Amen
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Audrey Chuat
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Laura Capolupo
- Institute of Bioengineering, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Prisca Liberali
- Friedrich Miescher Institute for Biomedical Research (FMI), 4058 Basel, Switzerland; University of Basel, 4056 Basel, Switzerland
| | - Giovanni D'Angelo
- Institute of Bioengineering, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland.
| | - F Gisou van der Goot
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland.
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6
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Overlapping and Distinct Functions of the Paralogous PagR Regulators of Bacillus anthracis. J Bacteriol 2022; 204:e0020822. [PMID: 36005808 PMCID: PMC9487532 DOI: 10.1128/jb.00208-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The Bacillus anthracis pagA gene, encoding the protective antigen component of anthrax toxin, is part of a bicistronic operon on pXO1 that codes for its own repressor, PagR1. In addition to the pagAR1 operon, PagR1 regulates sap and eag, two chromosome genes encoding components of the surface layer, a mounting structure for surface proteins involved in virulence. Genomic studies have revealed a PagR1 paralog, PagR2, encoded by a gene on pXO2. The amino acid sequences of the paralogues are 71% identical and show similarity to the ArsR family of transcription regulators. We determined that the expression of either rPagR1 or rPagR2 in a ΔpagR1 pXO1+/pXO2- (PagR1-PagR2) background repressed the expression of pagA, sap, eag, and a newly discovered target, atxA, encoding virulence activator AtxA. Despite the redundancy in PagR1 and PagR2 function, we determined that purified rPagR1 bound DNA corresponding to the control regions of all four target genes and existed as a dimer in cell lysates, whereas rPagR2 exhibited weak binding to the DNA of the pagA and atxA promoters, did not bind sap or eag promoter DNA, and did not appear as a dimer in cell lysates. A single amino acid change in PagR2, S81Y, designed to match the native Y81 of PagR1, allowed for DNA-binding to the sap and eag promoters. Moreover, the S81Y mutation allowed for the detection of PagR2 homomultimers in coaffinity purification experiments. Our results expand our knowledge of the roles of the paralogues in B. anthracis gene expression and provide a potential mechanistic basis for differences in the functions of these repressors. IMPORTANCE The protective antigen component of the anthrax toxin is essential for the delivery of the enzymatic components of the toxin into host target cells. The toxin genes and other virulence genes of B. anthracis are regulated by multiple trans-acting regulators that respond to a variety of host-related signals. PagR1, one such trans-acting regulator, connects the regulation of plasmid-encoded and chromosome-encoded virulence genes by controlling both protective antigen and surface layer protein expression. Whether PagR2, a paralog of PagR1, also functions as a trans-acting regulator was unknown. This work advances our knowledge of the complex model of virulence regulation in B. anthracis and furthers our understanding of the intriguing evolution of this pathogen.
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Scott H, Huang W, Andra K, Mamillapalli S, Gonti S, Day A, Zhang K, Mehzabeen N, Battaile KP, Raju A, Lovell S, Bann JG, Taylor DJ. Structure of the anthrax protective antigen D425A dominant negative mutant reveals a stalled intermediate state of pore maturation. J Mol Biol 2022; 434:167548. [PMID: 35304125 DOI: 10.1016/j.jmb.2022.167548] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 03/01/2022] [Accepted: 03/10/2022] [Indexed: 10/18/2022]
Abstract
The tripartite protein complex produced by anthrax bacteria (Bacillus anthracis) is a member of the AB family of β-barrel pore-forming toxins. The protective antigen (PA) component forms an oligomeric prepore that assembles on the host cell surface and serves as a scaffold for binding of lethal and edema factors. Following endocytosis, the acidic environment of the late endosome triggers a pH-induced conformational rearrangement to promote maturation of the PA prepore to a functional, membrane spanning pore that facilitates delivery of lethal and edema factors to the cytosol of the infected host. Here, we show that the dominant-negative D425A mutant of PA stalls anthrax pore maturation in an intermediate state at acidic pH. Our 2.7 Å cryo-EM structure of the intermediate state reveals structural rearrangements that involve constriction of the oligomeric pore combined with an intramolecular dissociation of the pore-forming module. In addition to defining the early stages of anthrax pore maturation, the structure identifies asymmetric conformational changes in the oligomeric pore that are influenced by the precise configuration of adjacent protomers.
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Affiliation(s)
- Harry Scott
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Wei Huang
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Kiran Andra
- Department of Chemistry, Wichita State University, Wichita, KS 67260, USA
| | | | - Srinivas Gonti
- Department of Chemistry, Wichita State University, Wichita, KS 67260, USA
| | - Alexander Day
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Kaiming Zhang
- Stanford Linear Accelerator Center and the Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Nurjahan Mehzabeen
- Protein Structure Laboratory, University of Kansas, Lawrence, KS 66047, USA
| | - Kevin P Battaile
- IMCA-CAT, APS, Argonne National Laboratory, 9700 South Cass Avenue, Building 435A, Argonne, IL 60439, USA
| | - Anjali Raju
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Scott Lovell
- Protein Structure Laboratory, University of Kansas, Lawrence, KS 66047, USA
| | - James G Bann
- Department of Chemistry, Wichita State University, Wichita, KS 67260, USA.
| | - Derek J Taylor
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Biochemistry, Case Western Reserve University, Cleveland, OH 44106, USA.
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Abstract
Intraluminal vesicles accumulate within the endosomal lumen before lysosomal delivery or extracellular release. A new study reports the development of an elegant assay showing that these vesicles can escape from the endosomal lumen by 'back-fusion' or 'retrofusion' with the endosomal limiting membrane.
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Liu W, Nestorovich EM. Anthrax toxin channel: What we know based on over 30 years of research. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183715. [PMID: 34332985 DOI: 10.1016/j.bbamem.2021.183715] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 07/21/2021] [Accepted: 07/24/2021] [Indexed: 10/20/2022]
Abstract
Protective antigen channel is the central component of the deadly anthrax exotoxin responsible for binding and delivery of the toxin's enzymatic lethal and edema factor components into the cytosol. The channel, which is more than three times longer than the lipid bilayer membrane thickness and has a 6-Å limiting diameter, is believed to provide a sophisticated unfoldase and translocase machinery for the foreign protein transport into the host cell cytosol. The tripartite toxin can be reengineered, one component at a time or collectively, to adapt it for the targeted cancer therapeutic treatments. In this review, we focus on the biophysical studies of the protective antigen channel-forming activity, small ion transport properties, enzymatic factor translocation, and blockage comparing it with the related clostridial binary toxin channels. We address issues linked to the anthrax toxin channel structural dynamics and lipid dependence, which are yet to become generally recognized as parts of the toxin translocation machinery.
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Affiliation(s)
- Wenxing Liu
- Department of Biology, The Catholic University of America, 620 Michigan Ave, Washington, DC 20064, USA
| | - Ekaterina M Nestorovich
- Department of Biology, The Catholic University of America, 620 Michigan Ave, Washington, DC 20064, USA.
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Gruenberg J. Life in the lumen: The multivesicular endosome. Traffic 2021; 21:76-93. [PMID: 31854087 PMCID: PMC7004041 DOI: 10.1111/tra.12715] [Citation(s) in RCA: 110] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 10/30/2019] [Accepted: 10/31/2019] [Indexed: 12/12/2022]
Abstract
The late endosomes/endo‐lysosomes of vertebrates contain an atypical phospholipid, lysobisphosphatidic acid (LBPA) (also termed bis[monoacylglycero]phosphate [BMP]), which is not detected elsewhere in the cell. LBPA is abundant in the membrane system present in the lumen of this compartment, including intralumenal vesicles (ILVs). In this review, the current knowledge on LBPA and LBPA‐containing membranes will be summarized, and their role in the control of endosomal cholesterol will be outlined. Some speculations will also be made on how this system may be overwhelmed in the cholesterol storage disorder Niemann‐Pick C. Then, the roles of intralumenal membranes in endo‐lysosomal dynamics and functions will be discussed in broader terms. Likewise, the mechanisms that drive the biogenesis of intralumenal membranes, including ESCRTs, will also be discussed, as well as their diverse composition and fate, including degradation in lysosomes and secretion as exosomes. This review will also discuss how intralumenal membranes are hijacked by pathogenic agents during intoxication and infection, and what is the biochemical composition and function of the intra‐endosomal lumenal milieu. Finally, this review will allude to the size limitations imposed on intralumenal vesicle functions and speculate on the possible role of LBPA as calcium chelator in the acidic calcium stores of endo‐lysosomes.
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Affiliation(s)
- Jean Gruenberg
- Biochemistry Department, University of Geneva, Geneva, Switzerland
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Koohsarian P, Talebi A, Rahnama MA, Zomorrod MS, Kaviani S, Jalili A. Reviewing the role of cardiac exosomes in myocardial repair at a glance. Cell Biol Int 2021; 45:1352-1363. [PMID: 33289229 DOI: 10.1002/cbin.11515] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 11/14/2020] [Accepted: 11/28/2020] [Indexed: 12/11/2022]
Abstract
Exosome-based therapy is an emerging novel approach for myocardial infarction (MI) treatment. Exosomes are identified as extracellular vesicles that are produced within multivesicular bodies in the cells' cytosols and then are secreted from the cells. Exosomes are 30-100 nm in diameter that are released from viable cells and are different from other secreted vesicles such as apoptotic bodies and microvesicles in their origin and contents such as RNAs, proteins, and nucleic acid. The recent advances in exosome research have demonstrated the role of these bionanovesicles in the physiological, pathological, and molecular aspects of the heart. The results of in vitro and preclinical models have shown that exosomes from different cardiac cells can improve cardiac function following MI. For example, mesenchymal stem cells (MSCs) and cardiac progenitor cells (CPCs) containing exosomes can affect the proliferation, survival, and differentiation of cardiac fibroblasts and cardiomyocytes. Moreover, MSCs- and CPCs-derived exosomes can enhance the migration of endothelial cells. Exosome-based therapy approaches augment the cardiac function by multiple means, such as reducing fibrosis, stimulation of vascular angiogenesis, and proliferation of cardiomyocytes that result in replacing damaged heart tissue with newly generated functional myocytes. This review article aims to briefly discuss the recent advancements in the role of secreted exosomes in myocardial repair by focusing on cardiac cells-derived exosomes.
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Affiliation(s)
- Parisa Koohsarian
- Department of Hematology and Cell Therapy, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Athar Talebi
- Department of Nervous System, Stem Cell Research Center, Semnan University of Medical Sciences, Semnan, Iran
| | - Mahshid A Rahnama
- Department of Hematology and Cell Therapy, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Mina S Zomorrod
- Department of Hematology and Cell Therapy, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Saeid Kaviani
- Department of Hematology and Cell Therapy, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Arsalan Jalili
- Department of Stem Cells and Developmental Biology at Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran.,Hematopoetic Stem Cell Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Abstract
Anthrax toxin is a major virulence factor of Bacillus anthracis, a Gram-positive bacterium which can form highly stable spores that are the causative agents of the disease, anthrax. While chiefly a disease of livestock, spores can be "weaponized" as a bio-terrorist agent, and can be deadly if not recognized and treated early with antibiotics. The intracellular pathways affected by the enzymes are broadly understood and are not discussed here. This chapter focuses on what is known about the assembly of secreted toxins on the host cell surface and how the toxin is delivered into the cytosol. The central component is the "Protective Antigen", which self-oligomerizes and forms complexes with its pay-load, either Lethal Factor or Edema Factor. It binds a host receptor, CMG2, or a close relative, triggering receptor-mediated endocytosis, and forms a remarkably elegant yet powerful machine that delivers toxic enzymes into the cytosol, powered only by the pH gradient across the membrane. We now have atomic structures of most of the starting, intermediate and final assemblies in the infectious process. Together with a major body of biophysical, mutational and biochemical work, these studies reveal a remarkable story of both how toxin assembly is choreographed in time and space.
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13
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Becker L, Verdurmen WPR, Plückthun A. Reengineering anthrax toxin protective antigen for improved receptor-specific protein delivery. BMC Biol 2020; 18:100. [PMID: 32792013 PMCID: PMC7427085 DOI: 10.1186/s12915-020-00827-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Accepted: 07/10/2020] [Indexed: 01/27/2023] Open
Abstract
Background To increase the size of the druggable proteome, it would be highly desirable to devise efficient methods to translocate designed binding proteins to the cytosol, as they could specifically target flat and hydrophobic protein-protein interfaces. If this could be done in a manner dependent on a cell surface receptor, two layers of specificity would be obtained: one for the cell type and the other for the cytosolic target. Bacterial protein toxins have naturally evolved such systems. Anthrax toxin consists of a pore-forming translocation unit (protective antigen (PA)) and a separate protein payload. When engineering PA to ablate binding to its own receptor and instead binding to a receptor of choice, by fusing a designed ankyrin repeat protein (DARPin), uptake in new cell types can be achieved. Results Prepore-to-pore conversion of redirected PA already occurs at the cell surface, limiting the amount of PA that can be administered and thus limiting the amount of delivered payload. We hypothesized that the reason is a lack of a stabilizing interaction with wild-type PA receptor. We have now reengineered PA to incorporate the binding domain of the anthrax receptor CMG2, followed by a DARPin, binding to the receptor of choice. This construct is indeed stabilized, undergoes prepore-to-pore conversion only in late endosomes, can be administered to much higher concentrations without showing toxicity, and consequently delivers much higher amounts of payload to the cytosol. Conclusion We believe that this reengineered system is an important step forward to addressing efficient cell-specific delivery of proteins to the cytosol.
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Affiliation(s)
- Lukas Becker
- Department of Biochemistry, University of Zurich, Winterthurerstr. 190, 8057, Zurich, Switzerland
| | - Wouter P R Verdurmen
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud University Medical Center, Geert Grooteplein 28, 6525 GA, Nijmegen, The Netherlands
| | - Andreas Plückthun
- Department of Biochemistry, University of Zurich, Winterthurerstr. 190, 8057, Zurich, Switzerland.
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Baharlooi H, Azimi M, Salehi Z, Izad M. Mesenchymal Stem Cell-Derived Exosomes: A Promising Therapeutic Ace Card to Address Autoimmune Diseases. Int J Stem Cells 2020; 13:13-23. [PMID: 31887849 PMCID: PMC7119210 DOI: 10.15283/ijsc19108] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 11/03/2019] [Indexed: 12/12/2022] Open
Abstract
With the development of novel treatments for autoimmune disorders, it has become a popular research focus which mesenchymal stem cells (MSCs) have the capacity to counteract with autoimmune diseases progression. One of the underlying mechanisms behind their activities is the release of extracellular vesicles especially exosomes. MSC-derived exosomes are hypoimmunogenic nanocarriers which contain numerous immunoregulatory factors and similar to other exosomes, are able to pass through boundaries like the blood-brain barrier (BBB). Accumulating evidence provided by animal studies has demonstrated that MSC-derived exosomes, as a novel therapy, can re-induce self-tolerance, without subsequent complications reported for other treatments. Therefore, therapeutic applications of MSC-derived exosomes are contributing to core advances in the field of autoimmune diseases. Here, we briefly describe the biological characteristics of MSC-derived exosomes and review the experimentally verified outcomes for autoimmune disease therapy purposes.
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Affiliation(s)
- Hussein Baharlooi
- Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Maryam Azimi
- Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.,Immunology Research Center, Institute of Immunology and Infectious Diseases, Iran University of Medical Sciences, Tehran, Iran
| | - Zahra Salehi
- Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Maryam Izad
- Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.,Multiple Sclerosis Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
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15
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Mesquita FS, van der Goot FG, Sergeeva OA. Mammalian membrane trafficking as seen through the lens of bacterial toxins. Cell Microbiol 2020; 22:e13167. [PMID: 32185902 PMCID: PMC7154709 DOI: 10.1111/cmi.13167] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/15/2020] [Accepted: 01/17/2020] [Indexed: 12/12/2022]
Abstract
A fundamental question of eukaryotic cell biology is how membrane organelles are organised and interact with each other. Cell biologists address these questions by characterising the structural features of membrane compartments and the mechanisms that coordinate their exchange. To do so, they must rely on variety of cargo molecules and treatments that enable targeted perturbation, localisation, and labelling of specific compartments. In this context, bacterial toxins emerged in cell biology as paradigm shifting molecules that enabled scientists to not only study them from the side of bacterial infection but also from the side of the mammalian host. Their selectivity, potency, and versatility made them exquisite tools for uncovering much of our current understanding of membrane trafficking mechanisms. Here, we will follow the steps that lead toxins until their intracellular targets, highlighting how specific events helped us comprehend membrane trafficking and establish the fundamentals of various cellular organelles and processes. Bacterial toxins will continue to guide us in answering crucial questions in cellular biology while also acting as probes for new technologies and applications.
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Affiliation(s)
| | | | - Oksana A Sergeeva
- Global Health Institute, School of Life Sciences, EPFL, Lausanne, Switzerland
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16
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Perry MR, Ionin B, Barnewall RE, Vassar ML, Reece JJ, Park S, Lemiale L, Skiadopoulos MH, Shearer JD, Savransky V. Development of a guinea pig inhalational anthrax model for evaluation of post-exposure prophylaxis efficacy of anthrax vaccines. Vaccine 2020; 38:2307-2314. [PMID: 32029323 DOI: 10.1016/j.vaccine.2020.01.068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 01/06/2020] [Accepted: 01/22/2020] [Indexed: 11/29/2022]
Abstract
A next-generation anthrax vaccine candidate, AV7909, is being developed for post-exposure prophylaxis (PEP) of inhalational anthrax in combination with the recommended course of antimicrobial therapy. Clinical efficacy studies of anthrax countermeasures in humans are not ethical or feasible, therefore, licensure of AV7909 for PEP is being pursued under the US Food and Drug Administration (FDA) Animal Rule, which requires that evidence of effectiveness be demonstrated in an animal model of anthrax, where results of studies in such a model can establish reasonable likelihood of AV7909 to produce clinical benefit in humans. Initial development of a PEP model for inhalational anthrax included evaluation of post-exposure ciprofloxacin pharmacokinetics (PK), tolerability and survival in guinea pigs treated with various ciprofloxacin dosing regimens. Three times per day (TID) intraperitoneal (IP) dosing with 7.5 mg/kg of ciprofloxacin initiated 1 day following inhalational anthrax challenge and continued for 14 days was identified as a well tolerated partially curative ciprofloxacin treatment regimen. The added benefit of AV7909 vaccination was evaluated in guinea pigs given the partially curative ciprofloxacin treatment regimen. Groups of ciprofloxacin-treated guinea pigs were vaccinated. 1 and 8 days post-challenge with serial dilutions of AV7909, a 1:16 dilution of AVA, or normal saline. A group of untreated guinea pigs was included as a positive control to confirm lethal B. anthracis exposure. Post-exposure vaccination with the AV7909 anthrax vaccine candidate administered in combination with the partially curative ciprofloxacin treatment significantly increased survival of guinea pigs compared to ciprofloxacin treatment alone. These results suggest that the developed model can be useful in demonstrating added value of the vaccine for PEP.
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Affiliation(s)
- Mark R Perry
- Battelle Biomedical Research Center, 1425 Plain City Georgesville Road, JM7, West Jefferson, OH 46162, USA
| | - Boris Ionin
- Emergent BioSolutions Inc., 300 Professional Drive, Gaithersburg, MD 20879, USA
| | - Roy E Barnewall
- Battelle Biomedical Research Center, 1425 Plain City Georgesville Road, JM7, West Jefferson, OH 46162, USA
| | - Michelle L Vassar
- Battelle Biomedical Research Center, 1425 Plain City Georgesville Road, JM7, West Jefferson, OH 46162, USA
| | - Joshua J Reece
- Emergent BioSolutions Inc., 300 Professional Drive, Gaithersburg, MD 20879, USA
| | - Sukjoon Park
- Emergent BioSolutions Inc., 300 Professional Drive, Gaithersburg, MD 20879, USA
| | - Laurence Lemiale
- Emergent BioSolutions Inc., 300 Professional Drive, Gaithersburg, MD 20879, USA
| | | | - Jeffry D Shearer
- Emergent BioSolutions Inc., 300 Professional Drive, Gaithersburg, MD 20879, USA
| | - Vladimir Savransky
- Emergent BioSolutions Inc., 300 Professional Drive, Gaithersburg, MD 20879, USA.
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17
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Yousafi Q, Azhar M, Khan MS, Mehmood A, Saleem S, Sajid MW, Hussain A, Kamal MA. Interaction of human dynein light chain 1 (DYNLL1) with enterochelin esterase ( Salmonella typhimurium) and protective antigen ( Bacillus anthraci) might be the potential cause of human infection. Saudi J Biol Sci 2019; 27:1396-1402. [PMID: 32346352 PMCID: PMC7182775 DOI: 10.1016/j.sjbs.2019.11.034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 11/21/2019] [Accepted: 11/26/2019] [Indexed: 12/11/2022] Open
Abstract
The cytoplasmic dynein light chain 1 (DYNLL1) is an important constituent of motor proteins complex. In human it is encoded by DYNLL1 gene. It is involved in cargo transport functions and interacts with many viral proteins with the help of short linear consensus motif sequence (K/R) XTQT. Viral proteins bind to DYNLL1 through its consensus short linear motif (SLiM) sequence to reach the target site in the cell and cause different infections in the host. It is still unknown if bacterial proteins also contain the same conserved SLiMs sequence through which they bind to this motor protein and cause infections. So, it is important to investigate the role of DYNLL1 in human bacterial infections. The interaction partner proteins of DYNLL1 against conserved viral motif sequences were predicted through PDBSum. Pairwise sequence alignment, between viral motif sequence and that of predicted proteins, was performed to identify conserved region in predicted interaction partners. Docking between the DYNLL1 and new pathogenic interaction partners was performed, by using PatchDock, to explore the protein-protein binding quality. Interactions of docked complexes were visualized by DimPlot. Three pathogenic bacterial proteins i.e., enterochelin esterase (3MGA), protective antigen (3J9C) and putative lipoprotein (4KT3) were selected as candidate interaction partners of DYNLL1. The putative lipoprotein (4KT3) showed low quality binding with DYNLL1. So, enterochelin esterase (3MGA) and protective antigen (3J9C) were speculated to be involved in human bacterial infections by using DYNLL1 to reach their target sites.
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Affiliation(s)
- Qudsia Yousafi
- Dept. Biosciences, COMSATS University Islamabad, Sahiwal, Pakistan
| | - Maria Azhar
- Dept. Biosciences, COMSATS University Islamabad, Sahiwal, Pakistan
| | | | - Asim Mehmood
- Dept. Biosciences, COMSATS University Islamabad, Sahiwal, Pakistan
| | - Shahzad Saleem
- Dept. Biosciences, COMSATS University Islamabad, Sahiwal, Pakistan
| | | | - Abrar Hussain
- Dept. Biosciences, COMSATS University Islamabad, Sahiwal, Pakistan
| | - Mohammad Amjad Kamal
- King Fahd Medical Research Center, King Abdulaziz University, P. O. Box 80216, Jeddah 21589, Saudi Arabia.,Enzymoics, 7 Peterlee Place, Hebersham, NSW 2770, Australia.,Novel Global Community Educational Foundation, Australia
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18
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Stiles BG. Clostridial Binary Toxins: Basic Understandings that Include Cell Surface Binding and an Internal "Coup de Grâce". Curr Top Microbiol Immunol 2019; 406:135-162. [PMID: 27380267 DOI: 10.1007/82_2016_11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Clostridium species can make a remarkable number of different protein toxins, causing many diverse diseases in humans and animals. The binary toxins of Clostridium botulinum, C. difficile, C. perfringens, and C. spiroforme are one group of enteric-acting toxins that attack the actin cytoskeleton of various cell types. These enterotoxins consist of A (enzymatic) and B (cell binding/membrane translocation) components that assemble on the targeted cell surface or in solution, forming a multimeric complex. Once translocated into the cytosol via endosomal trafficking and acidification, the A component dismantles the filamentous actin-based cytoskeleton via mono-ADP-ribosylation of globular actin. Knowledge of cell surface receptors and how these usurped, host-derived molecules facilitate intoxication can lead to novel ways of defending against these clostridial binary toxins. A molecular-based understanding of the various steps involved in toxin internalization can also unveil therapeutic intervention points that stop the intoxication process. Furthermore, using these bacterial proteins as medicinal shuttle systems into cells provides intriguing possibilities in the future. The pertinent past and state-of-the-art present, regarding clostridial binary toxins, will be evident in this chapter.
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Affiliation(s)
- Bradley G Stiles
- Biology Department, Wilson College, Chambersburg, PA, 17201, USA.
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19
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Farcasanu M, Wang AG, Uchański T, Bailey LJ, Yue J, Chen Z, Wu X, Kossiakoff A, Tang WJ. Rapid Discovery and Characterization of Synthetic Neutralizing Antibodies against Anthrax Edema Toxin. Biochemistry 2019; 58:2996-3004. [PMID: 31243996 DOI: 10.1021/acs.biochem.9b00184] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Anthrax, a lethal, weaponizable disease caused by Bacillus anthracis, acts through exotoxins that are primary mediators of systemic toxicity and also targets for neutralization by passive immunotherapy. The ease of engineering B. anthracis strains resistant to established therapy and the historic use of the microbe in bioterrorism present a compelling test case for platforms that permit the rapid and modular development of neutralizing agents. In vitro antigen-binding fragment (Fab) selection offers the advantages of speed, sequence level molecular control, and engineering flexibility compared to traditional monoclonal antibody pipelines. By screening an unbiased, chemically synthetic phage Fab library and characterizing hits in cell-based assays, we identified two high-affinity neutralizing Fabs, A4 and B7, against anthrax edema factor (EF), a key mediator of anthrax pathogenesis. Engineered homodimers of these Fabs exhibited potency comparable to that of the best reported neutralizing monoclonal antibody against EF at preventing EF-induced cyclic AMP production. Using internalization assays in COS cells, B7 was found to block steps prior to EF internalization. This work demonstrates the efficacy of synthetic alternatives to traditional antibody therapeutics against anthrax while also demonstrating a broadly generalizable, rapid, and modular screening pipeline for neutralizing antibody generation.
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Affiliation(s)
- Mara Farcasanu
- The Ben May Department for Cancer Research , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Andrew G Wang
- The Ben May Department for Cancer Research , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Tomasz Uchański
- Department of Biochemistry and Molecular Biology , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Lucas J Bailey
- Department of Biochemistry and Molecular Biology , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Jiping Yue
- The Ben May Department for Cancer Research , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Zhaochun Chen
- National Institute of Allergy and Infection , National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Xiaoyang Wu
- The Ben May Department for Cancer Research , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Anthony Kossiakoff
- Department of Biochemistry and Molecular Biology , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Wei-Jen Tang
- The Ben May Department for Cancer Research , The University of Chicago , Chicago , Illinois 60637 , United States
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20
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Perrin P, Jongsma MLM, Neefjes J, Berlin I. The labyrinth unfolds: architectural rearrangements of the endolysosomal system in antigen-presenting cells. Curr Opin Immunol 2019; 58:1-8. [DOI: 10.1016/j.coi.2018.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 12/18/2018] [Accepted: 12/20/2018] [Indexed: 12/31/2022]
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21
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Xavier MAE, Liu S, Leppla SH, Cornelissen B. Pre-labelling versus direct labelling of anthrax proteins for imaging of matrix metalloproteinases activity using DOTA-GA. Nucl Med Biol 2019; 72-73:49-54. [PMID: 31330412 PMCID: PMC7730038 DOI: 10.1016/j.nucmedbio.2019.07.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 06/19/2019] [Accepted: 07/17/2019] [Indexed: 12/16/2022]
Abstract
INTRODUCTION Increased activity of matrix metalloproteases (MMPs) is associated with reduced survival in several cancer subtypes. Aiming to produce an MMP tumour cell-selective cytotoxin, we genetically modified both components of the AB-type lethal toxin from Bacillus anthracis. Component A, Protective Antigen (PA-WT), was re-engineered to form an oligomeric pore in cell membranes only when cleaved by MMPs (PA-L1). The pore-translocation domain (LFn - N-terminal, 30 kDa) of the Lethal Factor (LF), component B, was fused to the catalytic domain of Pseudomonas exotoxin-A to increase its cytotoxic effect when delivered to cancerous cells. Here, we develop radiolabelled forms of LFn for MMP activity imaging by SPECT using the LFn/PA-L1 system. METHODS DOTA-GA-maleimide was conjugated to LFn to allow radiolabelling with 111In via two different routes: (1) LFn was conjugated with maleimide-DOTA-GA under mild conditions, and then radiolabelled in acidic conditions at 95°C, or (2) 111In was coordinated to maleimide-DOTA-GA first and then conjugated via maleimide chemistry to LFn. Circular Dichroism Spectroscopy of LFn was performed to evaluate changes in its secondary structure. Cell uptake assays using the differently labelled forms of [111In]In-DOTA-GA-LFn in the presence or not of PA-WT or PA-L1 were performed. RESULTS LFn was successfully radiolabelled by either strategy. Comparison of the secondary structure content of LFn exposed to 37°C or 95°C, showed a loss of alpha helix content at higher temperatures. Cell uptake of both forms of [111In]In-DOTA-GA-LFn, labelled directly or indirectly, was significantly higher in MMP-positive cells, in the presence of PA-L1, compared to controls. Notably, despite being exposed to high temperatures, uptake of directly labelled [111In]In-DOTA-GA-LFndir was higher than indirectly labelled [111In]In-DOTA-GA-LFnindir. CONCLUSIONS 111In-radiolabelling of LFn results in a functional molecule that targets MMP-activity in cells when combined with PA-L1. [111In]In-LFn/PA-L1 is a promising MMP activity imaging agent for SPECT imaging.
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Affiliation(s)
- Mary-Ann Elvina Xavier
- CRUK/MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom
| | - Shihui Liu
- Department of Medicine, Division of Infectious Diseases, University of Pittsburgh, Pittsburgh, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, USA
| | - Bart Cornelissen
- CRUK/MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom.
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22
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The Late Endosomal Pathway Regulates the Ciliary Targeting of Tetraspanin Protein Peripherin 2. J Neurosci 2019; 39:3376-3393. [PMID: 30819798 PMCID: PMC6495125 DOI: 10.1523/jneurosci.2811-18.2019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 01/18/2019] [Accepted: 02/10/2019] [Indexed: 12/11/2022] Open
Abstract
Peripherin 2 (PRPH2) is a tetraspanin protein concentrated in the light-sensing cilium (called the outer segment) of the vertebrate photoreceptor. The mechanism underlying the ciliary targeting of PRPH2 and the etiology of cone dystrophy caused by PRPH2 mutations remain elusive. Here we show that the late endosome (LE) is the main waystation that critically sorts newly synthesized PRPH2 to the cilium. PRPH2 is expressed in the luminal membrane of the LE. We delineate multiple C-terminal motifs of PRPH2 that distinctively regulate its LE and ciliary targeting through ubiquitination and binding to ESCRT (Endosomal Sorting Complexes Required for Transport) component Hrs. Using the newly developed TetOn-inducible system in transfected male and female mouse cones in vivo, we show that the entry of nascent PRPH2 into the cone outer segment can be blocked by either cone dystrophy-causing C-terminal mutations of PRPH2, or by short-term perturbation of the LE or recycling endosomal traffic. These findings open new avenues of research to explore the biological role of the LE in the biosynthetic pathway and the etiology of cone dystrophy caused by PRPH2 mutations and/or malfunctions of the LE.SIGNIFICANCE STATEMENT Peripherin 2 (PRPH2) is a tetraspanin protein abundantly expressed in the light-sensing cilium, the outer segment, of the vertebrate photoreceptor. The mechanism underlying the ciliary transport of PRPH2 is unclear. The present study reveals a novel ciliary targeting pathway, in which the newly synthesized PRPH2 is first targeted to the lumen of the late endosome (LE) en route to the cilia. We deciphered the protein motifs and the machinery that regulates the LE trafficking of PRPH2. Using a novel TetOn-inducible system in transfected mouse cones, we showed that the LE pathway of PRPH2 is critical for its outer segment expression. A cone dystrophy-causing mutation impairs the LE and ciliary targeting of PRPH2, implicating the relevance of LE to cone/macular degenerative diseases.
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Anthrax toxin requires ZDHHC5-mediated palmitoylation of its surface-processing host enzymes. Proc Natl Acad Sci U S A 2019; 116:1279-1288. [PMID: 30610172 PMCID: PMC6347675 DOI: 10.1073/pnas.1812588116] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Toxins exploit numerous pathways of their host cells to gain cellular entry and promote intoxication. Therefore, studying the action of toxins allows us to better understand basic mechanisms in cell biology. In this study, we found that ZDHHC5, an enzyme that adds a lipid posttranslational modification to cysteines of proteins, is responsible for allowing anthrax toxin to enter cells. This enzyme acts on proprotein convertases that are needed to cleave these toxins to their active forms. ZDHHC5 does not affect the enzymatic activity of these proteases, but allows them to encounter the toxin by favoring their partitioning in microdomains on the cell surface, domains where the toxin has previously been shown to preferentially reside. The protein acyl transferase ZDHHC5 was recently proposed to regulate trafficking in the endocytic pathway. Therefore, we explored the function of this enzyme in controlling the action of bacterial toxins. We found that ZDHHC5 activity is required for two very different toxins: the anthrax lethal toxin and the pore-forming toxin aerolysin. Both of these toxins have precursor forms, the protoxins, which can use the proprotein convertases Furin and PC7 for activation. We show that ZDHHC5 indeed affects the processing of the protoxins to their active forms. We found that Furin and PC7 can both be S-palmitoylated and are substrates of ZDHHC5. The impact of ZDHHC5 on Furin/PC7-mediated anthrax toxin cleavage is dual, having an indirect and a direct component. First, ZDHHC5 affects the homeostasis and trafficking of a subset of cellular proteins, including Furin and PC7, presumably by affecting the endocytic/recycling pathway. Second, while not inhibiting the protease activity per se, ZDHHC5-mediated Furin/PC7 palmitoylation is required for the cleavage of the anthrax toxin. Finally, we show that palmitoylation of Furin and PC7 promotes their association with plasma membrane microdomains. Both the receptor-bound toxin and the convertases are of very low abundance at the cell surface. Their encounter is unlikely on reasonable time scales. This work indicates that palmitoylation drives their encounter in specific domains, allowing processing and thereby intoxication of the cell.
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Intracellular Delivery: An Overview. TARGETED INTRACELLULAR DRUG DELIVERY BY RECEPTOR MEDIATED ENDOCYTOSIS 2019. [DOI: 10.1007/978-3-030-29168-6_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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25
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Gogoi H, Mani R, Bhatnagar R. A niosome formulation modulates the Th1/Th2 bias immune response in mice and also provides protection against anthrax spore challenge. Int J Nanomedicine 2018; 13:7427-7440. [PMID: 30532531 PMCID: PMC6241689 DOI: 10.2147/ijn.s153150] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Introduction In this study, we have investigated the immunogenicity and protective efficacy of a niosomal formulation encapsulating protective antigen (PA) and PA domain 4 (D4) of Bacillus anthracis. Methods Nonionic surfactant–based vesicles (NISV) + PA and NISV + D4 were prepared from span-60 and cholesterol by reverse-phase evaporation method and were evaluated for in vitro characteristics and immunological studies. Results Particle characterization using transmission electron microscopy and atomic force microscopy analysis showed that the niosomal formulation was spherical in shape. The entrapment efficiency values were calculated to be 58.5% and 44.75% for PA and D4, respectively. Confocal microscopy and flow cytometry studies showed an enhanced uptake of antigen in THP1 macrophages by niosome as compared to antigen only. An in vitro release assay showed a burst release of antigen from niosome within 24 hours followed by a gradual release for 144 hours. Immunological studies showed that both PA- and D4-encapsulated niosome elicited a robust IgG titer. Antibody isotyping and cytokine profile showed that NISV + PA and NISV + D4 enhanced both Th1 and Th2 responses in mice, suggesting a mixed Th1/Th2 response. Both NISV + PA and NISV + D4 elicited high levels of anti-inflammatory cytokine interleukin-10 with low levels of pro-inflammatory cytokine tumor necrosis factor-α, suggesting the anti-inflammatory property of niosome. Both the niosomal formulations were also able to confer protection against BA infection as compared to only PA and D4. Conclusion PA and D4 encapsulated NISV formulation could modulate both the Th1 and Th2 adaptive immune system and was found to be a better prophylactic against anthrax.
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Affiliation(s)
- Himanshu Gogoi
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India,
| | - Rajesh Mani
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India,
| | - Rakesh Bhatnagar
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India,
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26
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Kalu N, Atsmon-Raz Y, Momben Abolfath S, Lucas L, Kenney C, Leppla SH, Tieleman DP, Nestorovich EM. Effect of late endosomal DOBMP lipid and traditional model lipids of electrophysiology on the anthrax toxin channel activity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:2192-2203. [PMID: 30409515 DOI: 10.1016/j.bbamem.2018.08.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/09/2018] [Accepted: 08/19/2018] [Indexed: 01/26/2023]
Abstract
Anthrax toxin action requires triggering of natural endocytic transport mechanisms whereby the binding component of the toxin forms channels (PA63) within endosomal limiting and intraluminal vesicle membranes to deliver the toxin's enzymatic components into the cytosol. Membrane lipid composition varies at different stages of anthrax toxin internalization, with intraluminal vesicle membranes containing ~70% of anionic bis(monoacylglycero)phosphate lipid. Using model bilayer measurements, we show that membrane lipids can have a strong effect on the anthrax toxin channel properties, including the channel-forming activity, voltage-gating, conductance, selectivity, and enzymatic factor binding. Interestingly, the highest PA63 insertion rate was observed in bis(monoacylglycero)phosphate membranes. The molecular dynamics simulation data show that the conformational properties of the channel are different in bis(monoacylglycero)phosphate compared to PC, PE, and PS lipids. The anthrax toxin protein/lipid bilayer system can be advanced as a novel robust model to directly investigate lipid influence on membrane protein properties and protein/protein interactions.
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Affiliation(s)
- Nnanya Kalu
- Department of Biology, The Catholic University of America, 620 Michigan Ave NE, Washington 20064, DC, USA
| | - Yoav Atsmon-Raz
- Department of Biological Sciences, Centre for Molecular Simulation, University of Calgary, 2500 University Drive NW, Calgary T2N 1N4, Alberta, Canada.
| | - Sanaz Momben Abolfath
- Department of Biology, The Catholic University of America, 620 Michigan Ave NE, Washington 20064, DC, USA
| | - Laura Lucas
- Department of Biology, The Catholic University of America, 620 Michigan Ave NE, Washington 20064, DC, USA
| | - Clare Kenney
- Department of Biology, The Catholic University of America, 620 Michigan Ave NE, Washington 20064, DC, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda 20892, MD, USA
| | - D Peter Tieleman
- Department of Biological Sciences, Centre for Molecular Simulation, University of Calgary, 2500 University Drive NW, Calgary T2N 1N4, Alberta, Canada
| | - Ekaterina M Nestorovich
- Department of Biology, The Catholic University of America, 620 Michigan Ave NE, Washington 20064, DC, USA.
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Role of the Antigen Capture Pathway in the Induction of a Neutralizing Antibody Response to Anthrax Protective Antigen. mBio 2018; 9:mBio.00209-18. [PMID: 29487236 PMCID: PMC5829829 DOI: 10.1128/mbio.00209-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Toxin neutralizing antibodies represent the major mode of protective immunity against a number of toxin-mediated bacterial diseases, including anthrax; however, the cellular mechanisms that lead to optimal neutralizing antibody responses remain ill defined. Here we show that the cellular binding pathway of anthrax protective antigen (PA), the binding component of anthrax toxin, determines the toxin neutralizing antibody response to this antigen. PA, which binds cellular receptors and efficiently enters antigen-presenting cells by receptor-mediated endocytosis, was found to elicit robust anti-PA IgG and toxin neutralizing antibody responses. In contrast, a receptor binding-deficient mutant of PA, which does not bind receptors and only inefficiently enters antigen-presenting cells by macropinocytosis, elicited very poor antibody responses. A chimeric protein consisting of the receptor binding-deficient PA mutant tethered to the binding subunit of cholera toxin, which efficiently enters cells using the cholera toxin receptor rather than the PA receptor, elicited an anti-PA IgG antibody response similar to that elicited by wild-type PA; however, the chimeric protein elicited a poor toxin neutralizing antibody response. Taken together, our results demonstrate that the antigen capture pathway can dictate the magnitudes of the total IgG and toxin neutralizing antibody responses to PA as well as the ratio of the two responses.IMPORTANCE Neutralizing antibodies provide protection against a number of toxin-mediated bacterial diseases by inhibiting toxin action. Therefore, many bacterial vaccines are designed to induce a toxin neutralizing antibody response. We have used protective antigen (PA), the binding component of anthrax toxin, as a model antigen to investigate immune mechanisms important for the induction of robust toxin neutralizing antibody responses. We found that the pathway used by antigen-presenting cells to capture PA dictates the robustness of the neutralizing antibody response to this antigen. These results provide new insights into immune mechanisms that play an important role in the induction of toxin neutralizing antibody responses and may be useful in the design of new vaccines against toxin-mediated bacterial diseases.
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Kalu N, Alcaraz A, Yamini G, Momben Abolfath S, Lucas L, Kenney C, Aguilella VM, Nestorovich EM. Effect of endosomal acidification on small ion transport through the anthrax toxin PA 63 channel. FEBS Lett 2017; 591:3481-3492. [PMID: 28963849 DOI: 10.1002/1873-3468.12866] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 09/20/2017] [Accepted: 09/21/2017] [Indexed: 11/12/2022]
Abstract
Tight regulation of pH is critical for the structure and function of cells and organelles. The pH environment changes dramatically along the endocytic pathway, an internalization transport process that is 'hijacked' by many intracellularly active bacterial exotoxins, including the anthrax toxin. Here, we investigate the role of pH on single-channel properties of the anthrax toxin protective antigen (PA63 ). Using conductance and current noise analysis, blocker binding, ion selectivity, and poly(ethylene glycol) partitioning measurements, we show that the channel exists in two different open states ('maximum' and 'main') at pH ≥ 5.5, while only a maximum conductance state is detected at pH < 5.5. We describe two substantially distinct patterns of PA63 conductance dependence on KCl concentration uncovered at pH 6.5 and 4.5.
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Affiliation(s)
- Nnanya Kalu
- Department of Biology, The Catholic University of America, Washington, DC, USA
| | - Antonio Alcaraz
- Laboratory of Molecular Biophysics, Department of Physics, Universitat Jaume I, Castellón, Spain
| | - Goli Yamini
- Department of Biology, The Catholic University of America, Washington, DC, USA
| | | | - Laura Lucas
- Department of Biology, The Catholic University of America, Washington, DC, USA
| | - Clare Kenney
- Department of Biology, The Catholic University of America, Washington, DC, USA
| | - Vicente M Aguilella
- Laboratory of Molecular Biophysics, Department of Physics, Universitat Jaume I, Castellón, Spain
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Shorter SA, Gollings AS, Gorringe-Pattrick MAM, Coakley JE, Dyer PDR, Richardson SCW. The potential of toxin-based drug delivery systems for enhanced nucleic acid therapeutic delivery. Expert Opin Drug Deliv 2016; 14:685-696. [DOI: 10.1080/17425247.2016.1227781] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abstract
Exosomes are extracellular vesicles first described as such 30 years ago and since implicated in cell-cell communication and the transmission of disease states, and explored as a means of drug discovery. Yet fundamental questions about their biology remain unanswered. Here I explore what exosomes are, highlight the difficulties in studying them and explain the current definition and some of the outstanding issues in exosome biology.
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Affiliation(s)
- James R Edgar
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge, CB2 0XY, UK.
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31
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Chloroquine derivatives block the translocation pores and inhibit cellular entry of Clostridium botulinum C2 toxin and Bacillus anthracis lethal toxin. Arch Toxicol 2016; 91:1431-1445. [DOI: 10.1007/s00204-016-1716-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 04/14/2016] [Indexed: 10/21/2022]
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Friebe S, van der Goot FG, Bürgi J. The Ins and Outs of Anthrax Toxin. Toxins (Basel) 2016; 8:toxins8030069. [PMID: 26978402 PMCID: PMC4810214 DOI: 10.3390/toxins8030069] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 02/28/2016] [Accepted: 03/01/2016] [Indexed: 12/21/2022] Open
Abstract
Anthrax is a severe, although rather rare, infectious disease that is caused by the Gram-positive, spore-forming bacterium Bacillus anthracis. The infectious form is the spore and the major virulence factors of the bacterium are its poly-γ-D-glutamic acid capsule and the tripartite anthrax toxin. The discovery of the anthrax toxin receptors in the early 2000s has allowed in-depth studies on the mechanisms of anthrax toxin cellular entry and translocation from the endocytic compartment to the cytoplasm. The toxin generally hijacks the endocytic pathway of CMG2 and TEM8, the two anthrax toxin receptors, in order to reach the endosomes. From there, the pore-forming subunit of the toxin inserts into endosomal membranes and enables translocation of the two catalytic subunits. Insertion of the pore-forming unit preferentially occurs in intraluminal vesicles rather than the limiting membrane of the endosome, leading to the translocation of the enzymatic subunits in the lumen of these vesicles. This has important consequences that will be discussed. Ultimately, the toxins reach the cytosol where they act on their respective targets. Target modification has severe consequences on cell behavior, in particular on cells of the immune system, allowing the spread of the bacterium, in severe cases leading to host death. Here we will review the literature on anthrax disease with a focus on the structure of the toxin, how it enters cells and its immunological effects.
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Affiliation(s)
- Sarah Friebe
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland.
| | - F Gisou van der Goot
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland.
| | - Jérôme Bürgi
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland.
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do Vale A, Cabanes D, Sousa S. Bacterial Toxins as Pathogen Weapons Against Phagocytes. Front Microbiol 2016; 7:42. [PMID: 26870008 PMCID: PMC4734073 DOI: 10.3389/fmicb.2016.00042] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 01/11/2016] [Indexed: 12/31/2022] Open
Abstract
Bacterial toxins are virulence factors that manipulate host cell functions and take over the control of vital processes of living organisms to favor microbial infection. Some toxins directly target innate immune cells, thereby annihilating a major branch of the host immune response. In this review we will focus on bacterial toxins that act from the extracellular milieu and hinder the function of macrophages and neutrophils. In particular, we will concentrate on toxins from Gram-positive and Gram-negative bacteria that manipulate cell signaling or induce cell death by either imposing direct damage to the host cells cytoplasmic membrane or enzymatically modifying key eukaryotic targets. Outcomes regarding pathogen dissemination, host damage and disease progression will be discussed.
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Affiliation(s)
- Ana do Vale
- Host Interaction and Response, Instituto de Investigação e Inovação em Saúde, Universidade do PortoPorto, Portugal; Group of Fish Immunology and Vaccinology, Instituto de Biologia Molecular e Celular, Universidade do PortoPorto, Portugal
| | - Didier Cabanes
- Host Interaction and Response, Instituto de Investigação e Inovação em Saúde, Universidade do PortoPorto, Portugal; Group of Molecular Microbiology, Instituto de Biologia Molecular e Celular, Universidade do PortoPorto, Portugal
| | - Sandra Sousa
- Host Interaction and Response, Instituto de Investigação e Inovação em Saúde, Universidade do PortoPorto, Portugal; Group of Molecular Microbiology, Instituto de Biologia Molecular e Celular, Universidade do PortoPorto, Portugal
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Host Cell Chaperones Hsp70/Hsp90 and Peptidyl-Prolyl Cis/Trans Isomerases Are Required for the Membrane Translocation of Bacterial ADP-Ribosylating Toxins. Curr Top Microbiol Immunol 2016; 406:163-198. [PMID: 27197646 DOI: 10.1007/82_2016_14] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Bacterial ADP-ribosylating toxins are the causative agents for several severe human and animal diseases such as diphtheria, cholera, or enteric diseases. They display an AB-type structure: The enzymatically active A-domain attaches to the binding/translocation B-domain which then binds to a receptor on the cell surface. After receptor-mediated endocytosis, the B-domain facilitates the membrane translocation of the unfolded A-domain into the host cell cytosol. Here, the A-domain transfers an ADP-ribose moiety onto its specific substrate which leads to characteristic cellular effects and thus to severe clinical symptoms. Since the A-domain has to reach the cytosol to achieve a cytotoxic effect, the membrane translocation represents a crucial step during toxin uptake. Host cell chaperones including Hsp90 and protein-folding helper enzymes of the peptidyl-prolyl cis/trans isomerase (PPIase) type facilitate this membrane translocation of the unfolded A-domain for ADP-ribosylating toxins but not for toxins with a different enzyme activity. This review summarizes the uptake mechanisms of the ADP-ribosylating clostridial binary toxins, diphtheria toxin (DT) and cholera toxin (CT), with a special focus on the interaction of these toxins with the chaperones Hsp90 and Hsp70 and PPIases of the cyclophilin and FK506-binding protein families during the membrane translocation of their ADP-ribosyltransferase domains into the host cell cytosol. Moreover, the medical implications of host cell chaperones and PPIases as new drug targets for the development of novel therapeutic strategies against diseases caused by bacterial ADP-ribosylating toxins are discussed.
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Molecular assembly of lethal factor enzyme and pre-pore heptameric protective antigen in early stage of translocation. J Mol Model 2015; 22:7. [PMID: 26659402 DOI: 10.1007/s00894-015-2878-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 11/25/2015] [Indexed: 10/22/2022]
Abstract
During intoxication, the anthrax toxin lethal (LF) and edema (EF) factors initially assemble with the protective antigen (PA) on the plasma membrane of cells expressing the membrane-bound surface-exposed anthrax toxin receptor (ATR). This takes place at the physiological pH prior to entering the acidic environment of the endosome. We elucidated the molecular dynamics (MD) behaviors of the three-dimensional structure of the (PA63)7LF3 complex in various conformations and analyzed the dynamical properties of the fully loaded pre-pore complex on the plasma membrane at the physiological pH. The analysis points to the interaction networks of amino acids conserved between PA63 octamer and heptamer, which are not affected during the initial stage of the LFs binding. The simulations show an asymmetrical movement of the complex domains that directly affect LFs conformations. The conformational and structural alterations of the 2β2-2β3 loops of PA subunits are associated with pore formation. The early conformational changes of the loops appear as they peel off from the domain 2 toward domain 4 of each PA subunit. The LFs unfold in 1α1 segments of their N-terminal initiating the early stage of the pre-pore formation. The results indicate instable regions within the complex and provide important clues concerning the detail of fluctuating residues of the LF-PA interface regions at the early steps of toxins translocation.
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Dyer PDR, Shepherd TR, Gollings AS, Shorter SA, Gorringe-Pattrick MAM, Tang CK, Cattoz BN, Baillie L, Griffiths PC, Richardson SCW. Disarmed anthrax toxin delivers antisense oligonucleotides and siRNA with high efficiency and low toxicity. J Control Release 2015; 220:316-328. [PMID: 26546271 DOI: 10.1016/j.jconrel.2015.10.054] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 10/26/2015] [Accepted: 10/28/2015] [Indexed: 01/01/2023]
Abstract
Inefficient cytosolic delivery and vector toxicity contribute to the limited use of antisense oligonucleotides (ASOs) and siRNA as therapeutics. As anthrax toxin (Atx) accesses the cytosol, the purpose of this study was to evaluate the potential of disarmed Atx to deliver either ASOs or siRNA. We hypothesized that this delivery strategy would facilitate improved transfection efficiency while eliminating the toxicity seen for many vectors due to membrane destabilization. Atx complex formation with ASOs or siRNA was achieved via the in-frame fusion of either Saccharomyces cerevisiae GAL4 or Homo sapien sapien PKR (respectively) to a truncation of Atx lethal factor (LFn), which were used with Atx protective antigen (PA). Western immunoblotting confirmed the production of: LFN-GAL4, LFn-PKR and PA which were detected at ~45.9 kDa, ~37 kDa, and ~83 kDa respectively and small angle neutron scattering confirmed the ability of PA to form an annular structure with a radius of gyration of 7.0 ± 1.0 nm when placed in serum. In order to form a complex with LFn-GAL4, ASOs were engineered to contain a double-stranded region, and a cell free in vitro translation assay demonstrated that no loss of antisense activity above 30 pmol ASO was evident. The in vitro toxicity of both PA:LFn-GAL4:ASO and PA:LFn-PKR:siRNA complexes was low (IC50>100 μg/mL in HeLa and Vero cells) and subcellular fractionation in conjunction with microscopy confirmed the detection of LFn-GAL4 or LFn-PKR in the cytosol. Syntaxin5 (Synt5) was used as a model target gene to determine pharmacological activity. The PA:LFn-GAL4:ASO complexes had transfection efficiency approximately equivalent to Nucleofection® over a variety of ASO concentrations (24h post-transfection) and during a 72 h time course. In HeLa cells, at 200 pmol ASO (with PA:LFN-GAL4), 5.4 ± 2.0% Synt5 expression was evident relative to an untreated control after 24h. Using 200 pmol ASOs, Nucleofection® reduced Synt5 expression to 8.1 ± 2.1% after 24h. PA:LFn-GAL4:ASO transfection of non- or terminally-differentiated THP-1 cells and Vero cells resulted in 35.2 ± 19.1%, 36.4 ± 1.8% and 22.9 ± 6.9% (respectively) Synt5 expression after treatment with 200 pmol of ASO and demonstrated versatility. Nucleofection® with Stealth RNAi™ siRNA reduced HeLa Synt5 levels to 4.6 ± 6.1% whereas treatment with the PA:LFn-PKR:siRNA resulted in 8.5 ± 3.4% Synt5 expression after 24h (HeLa cells). These studies report for the first time an ASO and RNAi delivery system based upon protein toxin architecture that is devoid of polycations. This system may utilize regulated membrane back-fusion for the cytosolic delivery of ASOs and siRNA, which would account for the lack of toxicity observed. High delivery efficiency suggests further in vivo evaluation is warranted.
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Affiliation(s)
- Paul D R Dyer
- Intercellular Delivery Solutions Laboratory, Faculty of Engineering and Science, University of Greenwich, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK
| | - Thomas R Shepherd
- Intercellular Delivery Solutions Laboratory, Faculty of Engineering and Science, University of Greenwich, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK
| | - Alexander S Gollings
- Intercellular Delivery Solutions Laboratory, Faculty of Engineering and Science, University of Greenwich, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK
| | - Susan A Shorter
- Intercellular Delivery Solutions Laboratory, Faculty of Engineering and Science, University of Greenwich, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK
| | - Monique A M Gorringe-Pattrick
- Intercellular Delivery Solutions Laboratory, Faculty of Engineering and Science, University of Greenwich, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK
| | - Chun-Kit Tang
- Intercellular Delivery Solutions Laboratory, Faculty of Engineering and Science, University of Greenwich, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK
| | - Beatrice N Cattoz
- Department of Pharmaceutical, Chemical and Environmental Science, Faculty of Engineering and Science, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
| | - Les Baillie
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, King Edward VII Avenue, Cardiff CF10 3AX, UK
| | - Peter C Griffiths
- Department of Pharmaceutical, Chemical and Environmental Science, Faculty of Engineering and Science, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
| | - Simon C W Richardson
- Intercellular Delivery Solutions Laboratory, Faculty of Engineering and Science, University of Greenwich, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK.
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Zilbermintz L, Leonardi W, Jeong SY, Sjodt M, McComb R, Ho CLC, Retterer C, Gharaibeh D, Zamani R, Soloveva V, Bavari S, Levitin A, West J, Bradley KA, Clubb RT, Cohen SN, Gupta V, Martchenko M. Identification of agents effective against multiple toxins and viruses by host-oriented cell targeting. Sci Rep 2015; 5:13476. [PMID: 26310922 PMCID: PMC4550849 DOI: 10.1038/srep13476] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 07/28/2015] [Indexed: 01/25/2023] Open
Abstract
A longstanding and still-increasing threat to the effective treatment of infectious diseases is resistance to antimicrobial countermeasures. Potentially, the targeting of host proteins and pathways essential for the detrimental effects of pathogens offers an approach that may discover broad-spectrum anti-pathogen countermeasures and circumvent the effects of pathogen mutations leading to resistance. Here we report implementation of a strategy for discovering broad-spectrum host-oriented therapies against multiple pathogenic agents by multiplex screening of drugs for protection against the detrimental effects of multiple pathogens, identification of host cell pathways inhibited by the drug, and screening for effects of the agent on other pathogens exploiting the same pathway. We show that a clinically used antimalarial drug, Amodiaquine, discovered by this strategy, protects host cells against infection by multiple toxins and viruses by inhibiting host cathepsin B. Our results reveal the practicality of discovering broadly acting anti-pathogen countermeasures that target host proteins exploited by pathogens.
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Affiliation(s)
| | | | - Sun-Young Jeong
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - Megan Sjodt
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095
| | - Ryan McComb
- Keck Graduate Institute, Claremont, CA 91711
| | - Chi-Lee C Ho
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, 90095
| | - Cary Retterer
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | - Dima Gharaibeh
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | - Rouzbeh Zamani
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | - Veronica Soloveva
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | - Sina Bavari
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | | | - Joel West
- Keck Graduate Institute, Claremont, CA 91711
| | - Kenneth A Bradley
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, 90095
| | - Robert T Clubb
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095
| | - Stanley N Cohen
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - Vivek Gupta
- Keck Graduate Institute, Claremont, CA 91711
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Sun S, Zhou X, Corvera J, Gallick GE, Lin SH, Kuang J. ALG-2 activates the MVB sorting function of ALIX through relieving its intramolecular interaction. Cell Discov 2015; 1:15018. [PMID: 27462417 PMCID: PMC4860835 DOI: 10.1038/celldisc.2015.18] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 05/14/2015] [Indexed: 12/31/2022] Open
Abstract
The modular adaptor protein ALIX is critically involved in endosomal sorting complexes required for transport (ESCRT)-mediated multivesicular body (MVB) sorting of activated epidermal growth factor receptor (EGFR); however, ALIX contains a default intramolecular interaction that renders ALIX unable to perform this ESCRT function. The ALIX partner protein ALG-2 is a calcium-binding protein that belongs to the calmodulin superfamily. Prompted by a defined biological function of calmodulin, we determined the role of ALG-2 in regulating ALIX involvement in MVB sorting of activated EGFR. Our results show that calcium-dependent ALG-2 interaction with ALIX completely relieves the intramolecular interaction of ALIX and promotes CHMP4-dependent ALIX association with the membrane. EGFR activation induces increased ALG-2 interaction with ALIX, and this increased interaction is responsible for increased ALIX association with the membrane. Functionally, inhibition of ALIX activation by ALG-2 inhibits MVB sorting of activated EGFR as effectively as inhibition of ALIX interaction with CHMP4 does; however, inhibition of ALIX activation by ALG-2 does not affect cytokinetic abscission or equine infectious anemia virus (EIAV) budding. These findings indicate that calcium-dependent ALG-2 interaction with ALIX is specifically responsible for generating functional ALIX that supports MVB sorting of ubiquitinated membrane receptors.
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Affiliation(s)
- Sheng Sun
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA; The University of Texas Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Xi Zhou
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center , Houston, TX, USA
| | - Joe Corvera
- A&G Pharmaceuticals, Inc. , Baltimore, MD, USA
| | - Gary E Gallick
- The University of Texas Graduate School of Biomedical Sciences, Houston, TX, USA; Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Sue-Hwa Lin
- The University of Texas Graduate School of Biomedical Sciences, Houston, TX, USA; Department of Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Jian Kuang
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA; The University of Texas Graduate School of Biomedical Sciences, Houston, TX, USA
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Abstract
Anthrax is caused by the spore-forming, gram-positive bacterium Bacillus anthracis. The bacterium's major virulence factors are (a) the anthrax toxins and (b) an antiphagocytic polyglutamic capsule. These are encoded by two large plasmids, the former by pXO1 and the latter by pXO2. The expression of both is controlled by the bicarbonate-responsive transcriptional regulator, AtxA. The anthrax toxins are three polypeptides-protective antigen (PA), lethal factor (LF), and edema factor (EF)-that come together in binary combinations to form lethal toxin and edema toxin. PA binds to cellular receptors to translocate LF (a protease) and EF (an adenylate cyclase) into cells. The toxins alter cell signaling pathways in the host to interfere with innate immune responses in early stages of infection and to induce vascular collapse at late stages. This review focuses on the role of anthrax toxins in pathogenesis. Other virulence determinants, as well as vaccines and therapeutics, are briefly discussed.
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Affiliation(s)
- Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892; , , , ,
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892; , , , ,
| | - Catherine Vrentas
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892; , , , ,
| | - Andrei P Pomerantsev
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892; , , , ,
| | - Shihui Liu
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892; , , , ,
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40
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Scott CC, Vossio S, Vacca F, Snijder B, Larios J, Schaad O, Guex N, Kuznetsov D, Martin O, Chambon M, Turcatti G, Pelkmans L, Gruenberg J. Wnt directs the endosomal flux of LDL-derived cholesterol and lipid droplet homeostasis. EMBO Rep 2015; 16:741-52. [PMID: 25851648 DOI: 10.15252/embr.201540081] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 03/06/2015] [Indexed: 01/24/2023] Open
Abstract
The Wnt pathway, which controls crucial steps of the development and differentiation programs, has been proposed to influence lipid storage and homeostasis. In this paper, using an unbiased strategy based on high-content genome-wide RNAi screens that monitored lipid distribution and amounts, we find that Wnt3a regulates cellular cholesterol. We show that Wnt3a stimulates the production of lipid droplets and that this stimulation strictly depends on endocytosed, LDL-derived cholesterol and on functional early and late endosomes. We also show that Wnt signaling itself controls cholesterol endocytosis and flux along the endosomal pathway, which in turn modulates cellular lipid homeostasis. These results underscore the importance of endosome functions for LD formation and reveal a previously unknown regulatory mechanism of the cellular programs controlling lipid storage and endosome transport under the control of Wnt signaling.
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Affiliation(s)
- Cameron C Scott
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Stefania Vossio
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Fabrizio Vacca
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Berend Snijder
- Faculty of Sciences, Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Jorge Larios
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Olivier Schaad
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Nicolas Guex
- Vital-IT Group, Swiss Institute of Bioinformatics, University of Lausanne, Lausanne, Switzerland
| | - Dmitry Kuznetsov
- Vital-IT Group, Swiss Institute of Bioinformatics, University of Lausanne, Lausanne, Switzerland
| | - Olivier Martin
- Vital-IT Group, Swiss Institute of Bioinformatics, University of Lausanne, Lausanne, Switzerland
| | - Marc Chambon
- Biomolecular Screening Facility, SV-PTECH-PTCB, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Gerardo Turcatti
- Biomolecular Screening Facility, SV-PTECH-PTCB, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Lucas Pelkmans
- Faculty of Sciences, Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Jean Gruenberg
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
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41
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Friebe S, Deuquet J, van der Goot FG. Differential dependence on N-glycosylation of anthrax toxin receptors CMG2 and TEM8. PLoS One 2015; 10:e0119864. [PMID: 25781883 PMCID: PMC4363784 DOI: 10.1371/journal.pone.0119864] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 01/16/2015] [Indexed: 11/29/2022] Open
Abstract
ANTXR 1 and 2, also known as TEM8 and CMG2, are two type I membrane proteins, which have been extensively studied for their role as anthrax toxin receptors, but with a still elusive physiological function. Here we have analyzed the importance of N-glycosylation on folding, trafficking and ligand binding of these closely related proteins. We find that TEM8 has a stringent dependence on N-glycosylation. The presence of at least one glycan on each of its two extracellular domains, the vWA and Ig-like domains, is indeed necessary for efficient trafficking to the cell surface. In the absence of any N-linked glycans, TEM8 fails to fold correctly and is recognized by the ER quality control machinery. Expression of N-glycosylation mutants reveals that CMG2 is less vulnerable to sugar loss. The absence of N-linked glycans in one of the extracellular domains indeed has little impact on folding, trafficking or receptor function of the wild type protein expressed in tissue culture cells. N-glycans do, however, seem required in primary fibroblasts from human patients. Here, the presence of N-linked sugars increases the tolerance to mutations in cmg2 causing the rare genetic disease Hyaline Fibromatosis Syndrome. It thus appears that CMG2 glycosylation provides a buffer towards genetic variation by promoting folding of the protein in the ER lumen.
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Affiliation(s)
- Sarah Friebe
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Julie Deuquet
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - F. Gisou van der Goot
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- * E-mail:
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Nablo BJ, Panchal RG, Bavari S, Nguyen TL, Gussio R, Ribot W, Friedlander A, Chabot D, Reiner JE, Robertson JWF, Balijepalli A, Halverson KM, Kasianowicz JJ. Anthrax toxin-induced rupture of artificial lipid bilayer membranes. J Chem Phys 2014; 139:065101. [PMID: 23947891 DOI: 10.1063/1.4816467] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We demonstrate experimentally that anthrax toxin complexes rupture artificial lipid bilayer membranes when isolated from the blood of infected animals. When the solution pH is temporally acidified to mimic that process in endosomes, recombinant anthrax toxin forms an irreversibly bound complex, which also destabilizes membranes. The results suggest an alternative mechanism for the translocation of anthrax toxin into the cytoplasm.
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Affiliation(s)
- Brian J Nablo
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8120, USA
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43
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Lowe DE, Ya J, Glomski IJ. In trans complementation of lethal factor reveal roles in colonization and dissemination in a murine mouse model. PLoS One 2014; 9:e95950. [PMID: 24763227 PMCID: PMC3999102 DOI: 10.1371/journal.pone.0095950] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 04/02/2014] [Indexed: 12/04/2022] Open
Abstract
Lethal factor (LF) is a component of the B. anthracis exotoxin and critical for pathogenesis. The roles of LF in early anthrax pathogenesis, such as colonization and dissemination from the initial site of infection, are poorly understood. In mice models of infection, LF-deficient strains either have altered dissemination patterns or do not colonize, precluding analysis of the role of LF in colonization and dissemination from the portal of entry. Previous reports indicate rabbit and guinea pig models infected with LF-deficient strains have decreased virulence, yet the inability to use bioluminescent imaging techniques to track B. anthracis growth and dissemination in these hosts makes analysis of early pathogenesis challenging. In this study, the roles of LF early in infection were analyzed using bioluminescent signature tagged libraries of B. anthracis with varying ratios of LF-producing and LF-deficient clones. Populations where all clones produced LF and populations where only 40% of clones produce LF were equally virulent. The 40% LF-producing clones trans complimented the LF mutants and permitted them to colonize and disseminate. Decreases of the LF producing strains to 10% or 0.3% of the population led to increased host survival and decreased trans complementation of the LF mutants. A library with 10% LF producing clones could replicate and disseminate, but fewer clones disseminated and the mutant clones were less competitive than wild type. The inoculum with 0.3% LF producing clones could not colonize the host. This strongly suggests that between 10% and 0.3% of the population must produce LF in order to colonize. In total, these findings suggest that a threshold of LF must be produced in order for colonization and dissemination to occur in vivo. These observations suggest that LF has a major role in the early stages of colonization and dissemination.
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Affiliation(s)
- David E. Lowe
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Jason Ya
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Ian J. Glomski
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America
- * E-mail:
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44
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Nour AM, Modis Y. Endosomal vesicles as vehicles for viral genomes. Trends Cell Biol 2014; 24:449-54. [PMID: 24746011 DOI: 10.1016/j.tcb.2014.03.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 02/26/2014] [Accepted: 03/17/2014] [Indexed: 11/28/2022]
Abstract
The endocytic pathway is the principal cell entry pathway for large cargos and pathogens. Among the wide variety of specialized lipid structures within endosomes, the intraluminal vesicles (ILVs) formed in early endosomes (EEs) and transferred to late endosomal compartments are emerging as critical effectors of viral infection and immune recognition. Various viruses deliver their genomes into these ILVs, which serve as vehicles to transport the genome to the nuclear periphery for replication. When secreted as exosomes, ILVs containing viral genomes can infect permissive cells or activate immune responses in myeloid cells. We therefore propose that endosomal ILVs and exosomes are key effectors of viral pathogenesis.
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Affiliation(s)
- Adel M Nour
- Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, New Haven, CT 06520, USA
| | - Yorgo Modis
- Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, New Haven, CT 06520, USA.
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45
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Bissig C, Gruenberg J. ALIX and the multivesicular endosome: ALIX in Wonderland. Trends Cell Biol 2014; 24:19-25. [DOI: 10.1016/j.tcb.2013.10.009] [Citation(s) in RCA: 216] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 10/29/2013] [Accepted: 10/30/2013] [Indexed: 01/19/2023]
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46
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Slater LH, Clatworthy AE, Hung DT. Bacterial toxins and small molecules elucidate endosomal trafficking. Trends Microbiol 2013; 22:53-5. [PMID: 24370463 DOI: 10.1016/j.tim.2013.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 12/05/2013] [Indexed: 11/16/2022]
Abstract
Bacterial toxins and small molecules are useful tools for studying eukaryotic cell biology. In a recent issue of PNAS, Gillespie and colleagues describe a novel small molecule inhibitor of bacterial toxins and virus trafficking through the endocytic pathway, 4-bromobenzaldehyde N-(2,6-dimethylphenyl)semicarbazone (EGA), that prevents transport from early to late endosomes.
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Affiliation(s)
| | - Anne E Clatworthy
- Infectious Disease Program, Broad Institute of Harvard and MIT, Cambridge, MA, USA; Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, MA, USA
| | - Deborah T Hung
- Infectious Disease Program, Broad Institute of Harvard and MIT, Cambridge, MA, USA; Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, MA, USA; Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA.
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47
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Abrami L, Brandi L, Moayeri M, Brown MJ, Krantz BA, Leppla SH, van der Goot FG. Hijacking multivesicular bodies enables long-term and exosome-mediated long-distance action of anthrax toxin. Cell Rep 2013; 5:986-96. [PMID: 24239351 PMCID: PMC3866279 DOI: 10.1016/j.celrep.2013.10.019] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 10/01/2013] [Accepted: 10/11/2013] [Indexed: 12/21/2022] Open
Abstract
Anthrax lethal toxin is a classical AB toxin comprised of two components: protective antigen (PA) and lethal factor (LF). Here, we show that following assembly and endocytosis, PA forms a channel that translocates LF, not only into the cytosol, but also into the lumen of endosomal intraluminal vesicles (ILVs). These ILVs can fuse and release LF into the cytosol, where LF can proteolyze and disable host targets. We find that LF can persist in ILVs for days, fully sheltered from proteolytic degradation, both in vitro and in vivo. During this time, ILV-localized LF can be transmitted to daughter cells upon cell division. In addition, LF-containing ILVs can be delivered to the extracellular medium as exosomes. These can deliver LF to the cytosol of naive cells in a manner that is independent of the typical anthrax toxin receptor-mediated trafficking pathway, while being sheltered from neutralizing extracellular factors of the immune system.
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Affiliation(s)
- Laurence Abrami
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 19, CH-1015 Lausanne, Switzerland
| | - Lucia Brandi
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 19, CH-1015 Lausanne, Switzerland
| | - Mahtab Moayeri
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, U.S.A
| | - Michael J. Brown
- Department of Molecular & Cell Biology, University of California, Berkeley, CA, 94720, U.S.A
| | - Bryan A. Krantz
- Department of Molecular & Cell Biology, University of California, Berkeley, CA, 94720, U.S.A
- Department of Chemistry, University of California, Berkeley, CA, 94720, U.S.A
| | - Stephen H. Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, U.S.A
| | - F. G. van der Goot
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 19, CH-1015 Lausanne, Switzerland
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48
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Selective inhibitor of endosomal trafficking pathways exploited by multiple toxins and viruses. Proc Natl Acad Sci U S A 2013; 110:E4904-12. [PMID: 24191014 DOI: 10.1073/pnas.1302334110] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Pathogenic microorganisms and toxins have evolved a variety of mechanisms to gain access to the host-cell cytosol and thereby exert virulent effects upon the host. One common mechanism of cellular entry requires trafficking to an acidified endosome, which promotes translocation across the host membrane. To identify small-molecule inhibitors that block this process, a library of 30,000 small molecules was screened for inhibitors of anthrax lethal toxin. Here we report that 4-bromobenzaldehyde N-(2,6-dimethylphenyl)semicarbazone, the most active compound identified in the screen, inhibits intoxication by lethal toxin and blocks the entry of multiple other acid-dependent bacterial toxins and viruses into mammalian cells. This compound, which we named EGA, also delays lysosomal targeting and degradation of the EGF receptor, indicating that it targets host-membrane trafficking. In contrast, EGA does not block endosomal recycling of transferrin, retrograde trafficking of ricin, phagolysosomal trafficking, or phagosome permeabilization by Franciscella tularensis. Furthermore, EGA does not neutralize acidic organelles, demonstrating that its mechanism of action is distinct from pH-raising agents such as ammonium chloride and bafilomycin A1. EGA is a powerful tool for the study of membrane trafficking and represents a class of host-targeted compounds for therapeutic development to treat infectious disease.
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49
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Abstract
Intracellular organelles, including endosomes, show differences not only in protein but also in lipid composition. It is becoming clear from the work of many laboratories that the mechanisms necessary to achieve such lipid segregation can operate at very different levels, including the membrane biophysical properties, the interactions with other lipids and proteins, and the turnover rates or distribution of metabolic enzymes. In turn, lipids can directly influence the organelle membrane properties by changing biophysical parameters and by recruiting partner effector proteins involved in protein sorting and membrane dynamics. In this review, we will discuss how lipids are sorted in endosomal membranes and how they impact on endosome functions.
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Affiliation(s)
- Christin Bissig
- Biochemistry Department, University of Geneva, 1211 Geneva 4, Switzerland
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50
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Nour AM, Li Y, Wolenski J, Modis Y. Viral membrane fusion and nucleocapsid delivery into the cytoplasm are distinct events in some flaviviruses. PLoS Pathog 2013; 9:e1003585. [PMID: 24039574 PMCID: PMC3764215 DOI: 10.1371/journal.ppat.1003585] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 07/12/2013] [Indexed: 12/12/2022] Open
Abstract
Flaviviruses deliver their genome into the cell by fusing the viral lipid membrane to an endosomal membrane. The sequence and kinetics of the steps required for nucleocapsid delivery into the cytoplasm remain unclear. Here we dissect the cell entry pathway of virions and virus-like particles from two flaviviruses using single-particle tracking in live cells, a biochemical membrane fusion assay and virus infectivity assays. We show that the virus particles fuse with a small endosomal compartment in which the nucleocapsid remains trapped for several minutes. Endosomal maturation inhibitors inhibit infectivity but not membrane fusion. We propose a flavivirus cell entry mechanism in which the virus particles fuse preferentially with small endosomal carrier vesicles and depend on back-fusion of the vesicles with the late endosomal membrane to deliver the nucleocapsid into the cytoplasm. Virus entry modulates intracellular calcium release and phosphatidylinositol-3-phosphate kinase signaling. Moreover, the broadly cross-reactive therapeutic antibody scFv11 binds to virus-like particles and inhibits fusion. Many viruses package their genetic material into a lipid envelope. In order to deliver their genome into the host-cell cytoplasm, where it can be replicated, viruses must fuse their envelope with a cellular lipid membrane. This fusion event is therefore a critical step in the entry of an enveloped virus into the cell. In this study, we used various cell biological and biochemical approaches to map precisely the cell entry pathway of two major human pathogens from the flavivirus family, yellow fever virus and Japanese encephalitis virus. We discovered that these viruses co-opt cellular phospholipid signaling to promote the fusion of their envelope with the lipid envelope of small compartments inside the host-cell endosomes. The viral genome remains trapped in these compartments for several minutes until the compartments fuse with the surrounding endosomal membrane. It is this second membrane fusion event that delivers the viral genome into the cytoplasm. We also showed that the antibody fragment scFv11 inhibits the fusion of the viral envelope with small lipid compartments, explaining the therapeutic activity of the scFv11 antibody. Our work identifies new vulnerabilities in the entry pathway of flaviviruses, including the formation of small endosomal compartments and two distinct membrane fusion events involving these compartments.
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Affiliation(s)
- Adel M. Nour
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
| | - Yue Li
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
| | - Joseph Wolenski
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
| | - Yorgo Modis
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
- * E-mail:
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