1
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Hiller M, Diwo M, Wamp S, Gutsmann T, Lang C, Blankenfeldt W, Flieger A. Structure-function relationships underpin disulfide loop cleavage-dependent activation of Legionella pneumophila lysophospholipase A PlaA. Mol Microbiol 2024; 121:497-512. [PMID: 38130174 DOI: 10.1111/mmi.15201] [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: 11/01/2023] [Accepted: 11/03/2023] [Indexed: 12/23/2023]
Abstract
Legionella pneumophila, the causative agent of a life-threatening pneumonia, intracellularly replicates in a specialized compartment in lung macrophages, the Legionella-containing vacuole (LCV). Secreted proteins of the pathogen govern important steps in the intracellular life cycle including bacterial egress. Among these is the type II secreted PlaA which, together with PlaC and PlaD, belongs to the GDSL phospholipase family found in L. pneumophila. PlaA shows lysophospholipase A (LPLA) activity which increases after secretion and subsequent processing by the zinc metalloproteinase ProA within a disulfide loop. Activity of PlaA contributes to the destabilization of the LCV in the absence of the type IVB-secreted effector SdhA. We here present the 3D structure of PlaA which shows a typical α/β-hydrolase fold and reveals that the uncleaved disulfide loop forms a lid structure covering the catalytic triad S30/D278/H282. This leads to reduction of substrate access before activation; however, the catalytic site gets more accessible when the disulfide loop is processed. After structural modeling, a similar activation process is suggested for the GDSL hydrolase PlaC, but not for PlaD. Furthermore, the size of the PlaA substrate-binding site indicated preference toward phospholipids comprising ~16 carbon fatty acid residues which was verified by lipid hydrolysis, suggesting a molecular ruler mechanism. Indeed, mutational analysis changed the substrate profile with respect to fatty acid chain length. In conclusion, our analysis revealed the structural basis for the regulated activation and substrate preference of PlaA.
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Affiliation(s)
- Miriam Hiller
- Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch Institute, Wernigerode, Germany
| | - Maurice Diwo
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Sabrina Wamp
- Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch Institute, Wernigerode, Germany
| | - Thomas Gutsmann
- Research Center Borstel, Leibniz Lung Center, Division of Biophysics, Borstel, Germany
- CSSB-Centre for Structural Systems Biology, Hamburg, Germany
| | - Christina Lang
- Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch Institute, Wernigerode, Germany
| | - Wulf Blankenfeldt
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Antje Flieger
- Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch Institute, Wernigerode, Germany
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2
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Kellnerová S, Huber S, Massri M, Fleischer V, Losso K, Sarg B, Kremser L, Talasz H, He X, Varrone E, Brigotti M, Ardissino G, Orth-Höller D, Würzner R. Enzymatic Cleavage of Stx2a in the Gut and Identification of Pancreatic Elastase and Trypsin as Possible Main Cleavers. Microorganisms 2023; 11:2487. [PMID: 37894145 PMCID: PMC10609011 DOI: 10.3390/microorganisms11102487] [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: 07/06/2023] [Revised: 09/15/2023] [Accepted: 10/02/2023] [Indexed: 10/29/2023] Open
Abstract
Shiga toxins (Stxs), especially the Stx2a subtype, are the major virulence factors involved in enterohemorrhagic Escherichia coli (EHEC)-associated hemolytic uremic syndrome (eHUS), a life-threatening disease causing acute kidney injury, especially in children. After oral transmission and colonization in the gut, EHEC release Stx. Intracellular cleavage of the Stx A subunit, when followed by reduction, boosts the enzymatic activity that causes damage to targeted cells. This cleavage was assumed to be mostly mediated by furin during Stx intracellular trafficking. To investigate whether this cleavage could occur in the intestine, even prior to entering target cells, Stx2a A subunit structure (intact or cleaved) was characterized after its exposure to specific host factors present in human stool. The molecular weight of Stx2a A subunit/fragments was determined by immunoblotting after electrophoretic separation under reducing conditions. In this study, it was demonstrated that Stx2a is cleaved by certain human stool components. Trypsin and chymotrypsin-like elastase 3B (CELA3B), two serine proteases, were identified as potential candidates that can trigger the extracellular cleavage of Stx2a A subunit directly after its secretion by EHEC in the gut. Whether the observed cleavage indeed translates to natural infections and plays a role in eHUS pathogenesis has yet to be determined. If so, it seems likely that a host's protease profile could affect disease development by changing the toxin's biological features.
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Affiliation(s)
- Sára Kellnerová
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (S.K.); (S.H.); (M.M.); (V.F.)
| | - Silke Huber
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (S.K.); (S.H.); (M.M.); (V.F.)
| | - Mariam Massri
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (S.K.); (S.H.); (M.M.); (V.F.)
| | - Verena Fleischer
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (S.K.); (S.H.); (M.M.); (V.F.)
| | - Klemens Losso
- Institute of Analytical Chemistry and Radiochemistry, University of Innsbruck, 6020 Innsbruck, Austria;
- Department of Food Technology and Nutrition, MCI|The Entrepreneurial School, 6020 Innsbruck, Austria
| | - Bettina Sarg
- Protein Core Facility, Institute of Medical Biochemistry, Center of Chemistry and Biomedicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (B.S.); (L.K.); (H.T.)
| | - Leopold Kremser
- Protein Core Facility, Institute of Medical Biochemistry, Center of Chemistry and Biomedicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (B.S.); (L.K.); (H.T.)
| | - Heribert Talasz
- Protein Core Facility, Institute of Medical Biochemistry, Center of Chemistry and Biomedicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (B.S.); (L.K.); (H.T.)
| | - Xiaohua He
- Western Regional Research Center, U.S. Department of Agriculture, Agricultural Research Service, Albany, CA 74710, USA;
| | - Elisa Varrone
- Department of Medical and Surgical Sciences, School of Medicine, University of Bologna, 40126 Bologna, Italy; (E.V.); (M.B.)
| | - Maurizio Brigotti
- Department of Medical and Surgical Sciences, School of Medicine, University of Bologna, 40126 Bologna, Italy; (E.V.); (M.B.)
| | - Gianluigi Ardissino
- Center for HUS Prevention, Control and Management at Pediatric Nephrology, Dialysis and Transplant Unit, Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico, 20122 Milan, Italy;
| | - Dorothea Orth-Höller
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (S.K.); (S.H.); (M.M.); (V.F.)
- MB-LAB–Clinical Microbiology Laboratory, 6020 Innsbruck, Austria
| | - Reinhard Würzner
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (S.K.); (S.H.); (M.M.); (V.F.)
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Abstract
Analysis of the SARS-CoV-2 sequence revealed a multibasic furin cleavage site at the S1/S2 boundary of the spike protein distinguishing this virus from SARS-CoV. Furin, the best-characterized member of the mammalian proprotein convertases, is an ubiquitously expressed single pass type 1 transmembrane protein. Cleavage of SARS-CoV-2 spike protein by furin promotes viral entry into lung cells. While furin knockout is embryonically lethal, its knockout in differentiated somatic cells is not, thus furin provides an exciting therapeutic target for viral pathogens including SARS-CoV-2 and bacterial infections. Several peptide-based and small-molecule inhibitors of furin have been recently reported, and select cocrystal structures have been solved, paving the way for further optimization and selection of clinical candidates. This perspective highlights furin structure, substrates, recent inhibitors, and crystal structures with emphasis on furin's role in SARS-CoV-2 infection, where the current data strongly suggest its inhibition as a promising therapeutic intervention for SARS-CoV-2.
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Affiliation(s)
- Essam
Eldin A. Osman
- Department
of Medicinal Chemistry, College of Pharmacy, Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Pharmaceutical Chemistry, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt
| | - Alnawaz Rehemtulla
- Department
of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Nouri Neamati
- Department
of Medicinal Chemistry, College of Pharmacy, Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan 48109, United States
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4
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Shimizu M. Pathogenic functions and diagnostic utility of cytokines/chemokines in EHEC-HUS. Pediatr Int 2020; 62:308-315. [PMID: 31742829 DOI: 10.1111/ped.14053] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 10/07/2019] [Accepted: 11/15/2019] [Indexed: 12/13/2022]
Abstract
Hemolytic - uremic syndrome (HUS) is a severe complication of infection by Shiga toxin (STx)-producing enterohemorrhagic Escherichia coli. Hemolytic - uremic syndrome is defined clinically as a triad of non-immune microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injuries. Neurologic complications such as acute encephalopathy are also observed. In humans, endothelial cells, proximal tubular epithelial cells, mesangial cells, podocytes, intestinal epithelial cells, and monocytes / macrophages are susceptible to STx-mediated injury. Shiga toxin induces the secretion of inflammatory cytokines and chemokines from susceptible cells, including tumor necrosis factor-α interleukin (IL)-1, IL-6, and IL-8. These cytokines and chemokines contribute to the pathogenesis of HUS and encephalopathy by enhancing STx-induced cytotoxicity and inducing inflammatory cell infiltration. Serum cytokine/chemokine levels are therefore useful as indicators of disease activity and predictors of progression from acute kidney injury to chronic kidney disease. Anti-inflammation therapy combined with apheresis to remove excessive cytokines / chemokines and methylprednisolone pulse therapy to suppress cytokine/chemokine production may be an effective treatment regimen for severe E. coli-associated HUS. However, this regimen requires careful monitoring of potential side effects, such as infections, thrombus formation, and hypertension.
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Affiliation(s)
- Masaki Shimizu
- Department of Pediatrics, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
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5
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Watanabe-Takahashi M, Yamasaki S, Murata M, Kano F, Motoyama J, Yamate J, Omi J, Sato W, Ukai H, Shimasaki K, Ikegawa M, Tamura-Nakano M, Yanoshita R, Nishino Y, Miyazawa A, Natori Y, Toyama-Sorimachi N, Nishikawa K. Exosome-associated Shiga toxin 2 is released from cells and causes severe toxicity in mice. Sci Rep 2018; 8:10776. [PMID: 30018364 PMCID: PMC6050230 DOI: 10.1038/s41598-018-29128-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 06/27/2018] [Indexed: 12/20/2022] Open
Abstract
Shiga toxin (Stx), a major virulence factor of enterohemorrhagic Escherichia coli (EHEC), is classified into two subgroups, Stx1 and Stx2. Clinical data clearly indicate that Stx2 is associated with more severe toxicity than Stx1, but the molecular mechanism underlying this difference is not fully understood. Here, we found that after being incorporated into target cells, Stx2, can be transported by recycling endosomes, as well as via the regular retrograde transport pathway. However, transport via recycling endosome did not occur with Stx1. We also found that Stx2 is actively released from cells in a receptor-recognizing B-subunit dependent manner. Part of the released Stx2 is associated with microvesicles, including exosome markers (referred to as exo-Stx2), whose origin is in the multivesicular bodies that formed from late/recycling endosomes. Finally, intravenous administration of exo-Stx2 to mice causes more lethality and tissue damage, especially severe renal dysfunction and tubular epithelial cell damage, compared to a free form of Stx2. Thus, the formation of exo-Stx2 might contribute to the severity of Stx2 in vivo, suggesting new therapeutic strategies against EHEC infections.
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Affiliation(s)
- Miho Watanabe-Takahashi
- Department of Molecular Life Sciences, Graduate School of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Shinji Yamasaki
- International Prevention of Epidemics, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka, Japan
| | - Masayuki Murata
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Fumi Kano
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan
| | - Jun Motoyama
- Laboratory of Developmental Neurobiology, Graduate School of Brain Sciences, Doshisha University, Kyoto, Japan
| | - Jyoji Yamate
- Veterinary Pathology, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka, Japan
| | - Jumpei Omi
- Department of Molecular Life Sciences, Graduate School of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Waka Sato
- Department of Molecular Life Sciences, Graduate School of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Hirofumi Ukai
- Department of Molecular Life Sciences, Graduate School of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Kentaro Shimasaki
- Department of Molecular Life Sciences, Graduate School of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Masaya Ikegawa
- Genomics, Proteomics and Biomedical Functions, Graduate School of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Miwa Tamura-Nakano
- Communal Laboratory, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Ryohei Yanoshita
- Department of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Tokyo, Japan
| | - Yuri Nishino
- Graduate School of Life Science, University of Hyogo, Hyogo, Japan
| | - Atsuo Miyazawa
- Graduate School of Life Science, University of Hyogo, Hyogo, Japan
| | - Yasuhiro Natori
- Department of Health Chemistry, School of Pharmacy, Iwate Medical University, Iwate, Japan
| | - Noriko Toyama-Sorimachi
- Department of Molecular Immunology and Inflammation, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Kiyotaka Nishikawa
- Department of Molecular Life Sciences, Graduate School of Life and Medical Sciences, Doshisha University, Kyoto, Japan.
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6
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Lang C, Hiller M, Flieger A. Disulfide loop cleavage of Legionella pneumophila PlaA boosts lysophospholipase A activity. Sci Rep 2017; 7:16313. [PMID: 29176577 PMCID: PMC5701174 DOI: 10.1038/s41598-017-12796-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 09/14/2017] [Indexed: 02/07/2023] Open
Abstract
L. pneumophila, an important facultative intracellular bacterium, infects the human lung and environmental protozoa. At least fifteen phospholipases A (PLA) are encoded in its genome. Three of which, namely PlaA, PlaC, and PlaD, belong to the GDSL lipase family abundant in bacteria and higher plants. PlaA is a lysophospholipase A (LPLA) that destabilizes the phagosomal membrane in absence of a protective factor. PlaC shows PLA and glycerophospholipid: cholesterol acyltransferase (GCAT) activities which are activated by zinc metalloproteinase ProA via cleavage of a disulphide loop. In this work, we compared GDSL enzyme activities, their secretion, and activation of PlaA. We found that PlaA majorly contributed to LPLA, PlaC to PLA, and both substrate-dependently to GCAT activity. Western blotting revealed that PlaA and PlaC are type II-secreted and both processed by ProA. Interestingly, ProA steeply increased LPLA but diminished GCAT activity of PlaA. Deletion of 20 amino acids within a predicted disulfide loop of PlaA had the same effect. In summary, we propose a model by which ProA processes PlaA via disulfide loop cleavage leading to a steep increase in LPLA activity. Our results help to further characterize the L. pneumophila GDSL hydrolases, particularly PlaA, an enzyme acting in the Legionella-containing phagosome.
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Affiliation(s)
- Christina Lang
- Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch-Institut, Burgstr. 37, D-38855, Wernigerode, Germany
| | - Miriam Hiller
- Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch-Institut, Burgstr. 37, D-38855, Wernigerode, Germany
| | - Antje Flieger
- Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch-Institut, Burgstr. 37, D-38855, Wernigerode, Germany.
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7
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Hardes K, Ivanova T, Thaa B, McInerney GM, Klokk TI, Sandvig K, Künzel S, Lindberg I, Steinmetzer T. Elongated and Shortened Peptidomimetic Inhibitors of the Proprotein Convertase Furin. ChemMedChem 2017; 12:613-620. [PMID: 28334511 PMCID: PMC5572662 DOI: 10.1002/cmdc.201700108] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 03/16/2017] [Indexed: 12/13/2022]
Abstract
Novel elongated and shortened derivatives of the peptidomimetic furin inhibitor phenylacetyl-Arg-Val-Arg-4-amidinobenzylamide were synthesized. The most potent compounds, such as Nα (carbamidoyl)Arg-Arg-Val-Arg-4-amidinobenzylamide (Ki =6.2 pm), contain additional basic residues at the N terminus and inhibit furin in the low-picomolar range. Furthermore, to decrease the molecular weight of this inhibitor type, compounds that lack the P5 moiety were prepared. The best inhibitors of this series, 5-(guanidino)valeroyl-Val-Arg-4-amidinobenzylamide and its P3 tert-leucine analogue displayed Ki values of 2.50 and 1.26 nm, respectively. Selected inhibitors, together with our previously described 4-amidinobenzylamide derivatives as references, were tested in cell culture for their activity against furin-dependent infectious pathogens. The propagation of the alphaviruses Semliki Forest virus and chikungunya virus was strongly inhibited in the presence of selected derivatives. Moreover, a significant protective effect of the inhibitors against diphtheria toxin was observed. These results confirm that the inhibition of furin should be a promising approach for the short-term treatment of acute infectious diseases.
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Affiliation(s)
- Kornelia Hardes
- Institute of Pharmaceutical Chemistry, Philipps University, Marbacher Weg 6, D-35032 Marburg, Germany
| | - Teodora Ivanova
- Institute of Pharmaceutical Chemistry, Philipps University, Marbacher Weg 6, D-35032 Marburg, Germany
| | - Bastian Thaa
- Karolinska Institutet, Department of Microbiology, Tumor and Cell Biology, SE-171 77 Stockholm, Sweden
| | - Gerald M. McInerney
- Karolinska Institutet, Department of Microbiology, Tumor and Cell Biology, SE-171 77 Stockholm, Sweden
| | - Tove Irene Klokk
- Department of Molecular Cell Biology and Centre for Cancer Biomedicine, Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, NO-0310 Oslo, Norway
| | - Kirsten Sandvig
- Department of Molecular Cell Biology and Centre for Cancer Biomedicine, Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, NO-0310 Oslo, Norway
| | - Sebastian Künzel
- Faculty of Engineering Sciences, Hochschule Ansbach, Residenzstraße 8, D-91522 Ansbach, Germany
| | - Iris Lindberg
- Department of Anatomy and Neurobiology, University of Maryland Medical School, Baltimore, Maryland 21201
| | - Torsten Steinmetzer
- Institute of Pharmaceutical Chemistry, Philipps University, Marbacher Weg 6, D-35032 Marburg, Germany
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8
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Brandelli JR, Griener TP, Laing A, Mulvey G, Armstrong GD. The Effects of Shiga Toxin 1, 2 and Their Subunits on Cytokine and Chemokine Expression by Human Macrophage-Like THP-1 Cells. Toxins (Basel) 2015; 7:4054-66. [PMID: 26473922 PMCID: PMC4626720 DOI: 10.3390/toxins7104054] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 09/19/2015] [Accepted: 09/24/2015] [Indexed: 12/01/2022] Open
Abstract
Infection by Shiga toxin (Stx)-producing enterohemorrhagic Escherichia coli (EHEC) results in severe diarrhea, hemorrhagic colitis, and, occasionally, hemolytic-uremic syndrome (HUS). HUS is associated with an increase in pro-inflammatory cytokines and chemokines, many of which are produced by macrophages in the kidneys, indicating that localized host innate immunity likely plays a role in renal pathogenesis. EHEC serotypes may express one or two classes of serologically defined but structurally and functionally-related Shiga toxins called Stx1 and Stx2. Of these, Stx2 appears to be linked to higher rates of HUS than Stx1. To investigate a possible reason for this, we exposed human macrophage-like THP-1 cells to Stx1 or Stx2 and then used the Luminex multiplex system to assess cytokine/chemokine concentrations in culture supernatant solutions. This analysis revealed that, relative to Stx1, Stx2 significantly caused increased expression of GRO, G-CSF, IL-1β, IL-8 and TNFα in macrophage-like THP-1 cells. This was determined to not be due to a difference in cytotoxicity since both Stx1 and Stx2 displayed similar cytotoxic activities on macrophage-like THP-1 cells. These observations indicate that, in vitro, Stx2 can provoke a greater pro-inflammatory response than Stx1 in macrophages and provides a possible partial explanation for higher rates of HUS in patients infected with EHEC strains expressing Stx2. To begin to determine a mechanism for Shiga toxin-mediated cytokine production, we exposed macrophage-like THP-1 cells to Stx1 or Stx2 A and B subunits. Luminex analysis of cytokines in cell culture supernatant solutions demonstrated that neither subunit alone induced a cytokine response in THP-1 cells.
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Affiliation(s)
- Jeremy R Brandelli
- Department of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada.
| | - Thomas P Griener
- Department of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada.
| | - Austin Laing
- Department of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada.
| | - George Mulvey
- Department of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada.
| | - Glen D Armstrong
- Department of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada.
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9
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Hardes K, Becker GL, Lu Y, Dahms SO, Köhler S, Beyer W, Sandvig K, Yamamoto H, Lindberg I, Walz L, von Messling V, Than ME, Garten W, Steinmetzer T. Novel Furin Inhibitors with Potent Anti-infectious Activity. ChemMedChem 2015; 10:1218-31. [PMID: 25974265 DOI: 10.1002/cmdc.201500103] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Indexed: 11/10/2022]
Abstract
New peptidomimetic furin inhibitors with unnatural amino acid residues in the P3 position were synthesized. The most potent compound 4-guanidinomethyl-phenylacteyl-Arg-Tle-Arg-4-amidinobenzylamide (MI-1148) inhibits furin with a Ki value of 5.5 pM. The derivatives also strongly inhibit PC1/3, whereas PC2 is less affected. Selected inhibitors were tested in cell culture for antibacterial and antiviral activity against infectious agents known to be dependent on furin activity. A significant protective effect against anthrax and diphtheria toxin was observed in the presence of the furin inhibitors. Furthermore, the spread of the highly pathogenic H5N1 and H7N1 avian influenza viruses and propagation of canine distemper virus was strongly inhibited. Inhibitor MI-1148 was crystallized in complex with human furin. Its N-terminal guanidinomethyl group in the para position of the P5 phenyl ring occupies the same position as that found previously for a structurally related inhibitor containing this substitution in the meta position, thereby maintaining all of the important P5 interactions. Our results confirm that the inhibition of furin is a promising strategy for a short-term treatment of acute infectious diseases.
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Affiliation(s)
- Kornelia Hardes
- Institute of Pharmaceutical Chemistry, Philipps University, Marbacher Weg 6, 35032 Marburg (Germany)
| | - Gero L Becker
- Institute of Pharmaceutical Chemistry, Philipps University, Marbacher Weg 6, 35032 Marburg (Germany)
| | - Yinghui Lu
- Institute of Virology, Philipps University, Hans-Meerwein-Strasse 2, Marburg (Germany)
| | - Sven O Dahms
- Protein Crystallography Group, Leibniz Institute for Age Research-Fritz Lipmann Institute (FLI), Beutenbergstrasse 11, 07745 Jena (Germany)
| | - Susanne Köhler
- Institute of Environmental and Animal Hygiene, University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart (Germany)
| | - Wolfgang Beyer
- Institute of Environmental and Animal Hygiene, University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart (Germany)
| | - Kirsten Sandvig
- Department of Biochemistry and Centre for Cancer Biomedicine, Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, 0310 Oslo (Norway)
| | - Hiroyuki Yamamoto
- Department of Anatomy and Neurobiology, University of Maryland, Baltimore, Maryland 21201 (USA)
| | - Iris Lindberg
- Department of Anatomy and Neurobiology, University of Maryland, Baltimore, Maryland 21201 (USA)
| | - Lisa Walz
- Veterinary Medicine Division, Paul-Ehrlich-Institute, Federal Institute for Vaccines and Biomedicines, Paul-Ehrlich-Strasse 51-59, 63225 Langen (Germany)
| | - Veronika von Messling
- Veterinary Medicine Division, Paul-Ehrlich-Institute, Federal Institute for Vaccines and Biomedicines, Paul-Ehrlich-Strasse 51-59, 63225 Langen (Germany)
| | - Manuel E Than
- Protein Crystallography Group, Leibniz Institute for Age Research-Fritz Lipmann Institute (FLI), Beutenbergstrasse 11, 07745 Jena (Germany)
| | - Wolfgang Garten
- Institute of Virology, Philipps University, Hans-Meerwein-Strasse 2, Marburg (Germany)
| | - Torsten Steinmetzer
- Institute of Pharmaceutical Chemistry, Philipps University, Marbacher Weg 6, 35032 Marburg (Germany).
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10
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Márquez LB, Velázquez N, Repetto HA, Paton AW, Paton JC, Ibarra C, Silberstein C. Effects of Escherichia coli subtilase cytotoxin and Shiga toxin 2 on primary cultures of human renal tubular epithelial cells. PLoS One 2014; 9:e87022. [PMID: 24466317 PMCID: PMC3897771 DOI: 10.1371/journal.pone.0087022] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 12/17/2013] [Indexed: 12/21/2022] Open
Abstract
Shiga toxin (Stx)-producing Escherichia coli (STEC) cause post-diarrhea Hemolytic Uremic Syndrome (HUS), which is the most common cause of acute renal failure in children in many parts of the world. Several non-O157 STEC strains also produce Subtilase cytotoxin (SubAB) that may contribute to HUS pathogenesis. The aim of the present work was to examine the cytotoxic effects of SubAB on primary cultures of human cortical renal tubular epithelial cells (HRTEC) and compare its effects with those produced by Shiga toxin type 2 (Stx2), in order to evaluate their contribution to renal injury in HUS. For this purpose, cell viability, proliferation rate, and apoptosis were assayed on HRTEC incubated with SubAB and/or Stx2 toxins. SubAB significantly reduced cell viability and cell proliferation rate, as well as stimulating cell apoptosis in HRTEC cultures in a time dependent manner. However, HRTEC cultures were significantly more sensitive to the cytotoxic effects of Stx2 than those produced by SubAB. No synergism was observed when HRTEC were co-incubated with both SubAB and Stx2. When HRTEC were incubated with the inactive SubAA272B toxin, results were similar to those in untreated control cells. Similar stimulation of apoptosis was observed in Vero cells incubated with SubAB or/and Stx2, compared to HRTEC. In conclusion, primary cultures of HRTEC are significantly sensitive to the cytotoxic effects of SubAB, although, in a lesser extent compared to Stx2.
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Affiliation(s)
- Laura B. Márquez
- Laboratorio de Investigaciones Biomédicas, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Paraguay, Buenos Aires, Argentina
| | - Natalia Velázquez
- Laboratorio de Investigaciones Biomédicas, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Paraguay, Buenos Aires, Argentina
| | - Horacio A. Repetto
- Departamento de Pediatría, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Adrienne W. Paton
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, S.A., Australia
| | - James C. Paton
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, S.A., Australia
| | - Cristina Ibarra
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Claudia Silberstein
- Laboratorio de Investigaciones Biomédicas, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Paraguay, Buenos Aires, Argentina
- * E-mail:
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11
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Gagnon H, Beauchemin S, Kwiatkowska A, Couture F, D'Anjou F, Levesque C, Dufour F, Desbiens AR, Vaillancourt R, Bernard S, Desjardins R, Malouin F, Dory YL, Day R. Optimization of furin inhibitors to protect against the activation of influenza hemagglutinin H5 and Shiga toxin. J Med Chem 2013; 57:29-41. [PMID: 24359257 DOI: 10.1021/jm400633d] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Proprotein convertases (PCs) are crucial in the processing and entry of viral or bacterial protein precursors and confer increased infectivity of pathogens bearing a PC activation site, which results in increased symptom severity and lethality. Previously, we developed a nanomolar peptide inhibitor of PCs to prevent PC activation of infectious agents. Herein, we describe a peptidomimetic approach that increases the stability of this inhibitor for use in vivo to prevent systemic infections and cellular damage, such as that caused by influenza H5N1 and Shiga toxin. The addition of azaβ(3)-amino acids to both termini of the peptide successfully prevented influenza hemagglutinin 5 fusogenicity and Shiga toxin Vero toxicity in cell-based assays. The results from a cell-based model using stable shRNA-induced proprotein convertase knockdown indicate that only furin is the major proprotein convertase required for HA5 cleavage.
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Affiliation(s)
- Hugo Gagnon
- Institut de Pharmacologie de Sherbrooke (IPS) and Département de Chirurgie/Urologie, Faculté de Médecine et des Sciences de la Santé (FMSS), Université de Sherbrooke , 3001, 12e Avenue Nord, Sherbrooke, Québec J1H 5N4, Canada
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12
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Mukhopadhyay S, Linstedt AD. Retrograde trafficking of AB₅ toxins: mechanisms to therapeutics. J Mol Med (Berl) 2013; 91:1131-41. [PMID: 23665994 DOI: 10.1007/s00109-013-1048-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 04/23/2013] [Accepted: 04/24/2013] [Indexed: 01/28/2023]
Abstract
Bacterial AB5 toxins are a clinically relevant class of exotoxins that include several well-known members such as Shiga, cholera, and pertussis toxins. Infections with toxin-producing bacteria cause devastating human diseases that affect millions of individuals each year and have no definitive medical treatment. The molecular targets of AB5 toxins reside in the cytosol of infected cells, and the toxins reach the cytosol by trafficking through the retrograde membrane transport pathway that avoids degradative late endosomes and lysosomes. Focusing on Shiga toxin as the archetype member, we review recent advances in understanding the molecular mechanisms involved in the retrograde trafficking of AB5 toxins and highlight how these basic science advances are leading to the development of a promising new therapeutic approach based on inhibiting toxin transport.
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Affiliation(s)
- Somshuvra Mukhopadhyay
- Division of Pharmacology & Toxicology, College of Pharmacy and Institute for Cellular & Molecular Biology, The University of Texas at Austin, Austin, TX, 78712, USA
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13
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Bergan J, Dyve Lingelem AB, Simm R, Skotland T, Sandvig K. Shiga toxins. Toxicon 2012; 60:1085-107. [PMID: 22960449 DOI: 10.1016/j.toxicon.2012.07.016] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 06/19/2012] [Accepted: 07/25/2012] [Indexed: 02/03/2023]
Abstract
Shiga toxins are virulence factors produced by the bacteria Shigella dysenteriae and certain strains of Escherichia coli. There is currently no available treatment for disease caused by these toxin-producing bacteria, and understanding the biology of the Shiga toxins might be instrumental in addressing this issue. In target cells, the toxins efficiently inhibit protein synthesis by inactivating ribosomes, and they may induce signaling leading to apoptosis. To reach their cytoplasmic target, Shiga toxins are endocytosed and transported by a retrograde pathway to the endoplasmic reticulum, before the enzymatically active moiety is translocated to the cytosol. The toxins thereby serve as powerful tools to investigate mechanisms of intracellular transport. Although Shiga toxins are a serious threat to human health, the toxins may be exploited for medical purposes such as cancer therapy or imaging.
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Affiliation(s)
- Jonas Bergan
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Norway
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14
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Lang C, Rastew E, Hermes B, Siegbrecht E, Ahrends R, Banerji S, Flieger A. Zinc metalloproteinase ProA directly activates Legionella pneumophila PlaC glycerophospholipid:cholesterol acyltransferase. J Biol Chem 2012; 287:23464-78. [PMID: 22582391 DOI: 10.1074/jbc.m112.346387] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Enzymes secreted by Legionella pneumophila, such as phospholipases A (PLAs) and glycerophospholipid:cholesterol acyltransferases (GCATs), may target host cell lipids and therefore contribute to the establishment of Legionnaires disease. L. pneumophila possesses three proteins, PlaA, PlaC, and PlaD, belonging to the GDSL family of lipases/acyltransferases. We have shown previously that PlaC is the major GCAT secreted by L. pneumophila and that the zinc metalloproteinase ProA is essential for GCAT activity. Here we characterized the mode of PlaC GCAT activation and determined that ProA directly processes PlaC. We further found that not only cholesterol but also ergosterol present in protozoa was palmitoylated by PlaC. Such ester formations were not induced by either PlaA or PlaD. PlaD was shown here to possess lysophospholipase A activity, and interestingly, all three GDSL enzymes transferred short chain fatty acids to sterols. The three single putative catalytic amino acids (Ser-37, Asp-398, and His-401) proved essential for all PlaC-associated PLA, lysophospholipase A, and GCAT activities. A further four cysteine residues are important for the PLA/GCAT activities as well as their oxidized state, and we therefore conclude that PlaC likely forms at least one disulfide loop. Analysis of cleavage site and loop deletion mutants suggested that for GCAT activation deletion of several amino acids within the loop is necessary rather than cleavage at a single site. Our data therefore suggest a novel enzyme inhibition/activation mechanism where a disulfide loop inhibits PlaC GCAT activity until the protein is exported to the external space where it is ProA-activated.
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Affiliation(s)
- Christina Lang
- Division of Bacterial Infections, Robert Koch-Institut, Burgstrasse 37, 38855 Wernigerode, Germany
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15
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Becker GL, Lu Y, Hardes K, Strehlow B, Levesque C, Lindberg I, Sandvig K, Bakowsky U, Day R, Garten W, Steinmetzer T. Highly potent inhibitors of proprotein convertase furin as potential drugs for treatment of infectious diseases. J Biol Chem 2012; 287:21992-2003. [PMID: 22539349 DOI: 10.1074/jbc.m111.332643] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Optimization of our previously described peptidomimetic furin inhibitors was performed and yielded several analogs with a significantly improved activity. The most potent compounds containing an N-terminal 4- or 3-(guanidinomethyl)phenylacetyl residue inhibit furin with K(i) values of 16 and 8 pM, respectively. These analogs inhibit other proprotein convertases, such as PC1/3, PC4, PACE4, and PC5/6, with similar potency, whereas PC2, PC7, and trypsin-like serine proteases are poorly affected. Incubation of selected compounds with Madin-Darby canine kidney cells over a period of 96 h revealed that they exhibit great stability, making them suitable candidates for further studies in cell culture. Two of the most potent derivatives were used to inhibit the hemagglutinin cleavage and viral propagation of a highly pathogenic avian H7N1 influenza virus strain. The treatment with inhibitor 24 (4-(guanidinomethyl)phenylacetyl-Arg-Val-Arg-4-amidinobenzylamide) resulted in significantly delayed virus propagation compared with an inhibitor-free control. The same analog was also effective in inhibiting Shiga toxin activation in HEp-2 cells. This antiviral effect, as well as the protective effect against a bacterial toxin, suggests that inhibitors of furin or furin-like proprotein convertases could represent promising lead structures for future drug development, in particular for the treatment of infectious diseases.
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Affiliation(s)
- Gero L Becker
- Institute of Pharmaceutical Chemistry, Philipps University, 35032 Marburg, Germany
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16
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Lukyanenko V, Malyukova I, Hubbard A, Delannoy M, Boedeker E, Zhu C, Cebotaru L, Kovbasnjuk O. Enterohemorrhagic Escherichia coli infection stimulates Shiga toxin 1 macropinocytosis and transcytosis across intestinal epithelial cells. Am J Physiol Cell Physiol 2011; 301:C1140-9. [PMID: 21832249 DOI: 10.1152/ajpcell.00036.2011] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Gastrointestinal infection with Shiga toxins producing enterohemorrhagic Escherichia coli causes the spectrum of gastrointestinal and systemic complications, including hemorrhagic colitis and hemolytic uremic syndrome, which is fatal in ∼10% of patients. However, the molecular mechanisms of Stx endocytosis by enterocytes and the toxins cross the intestinal epithelium are largely uncharacterized. We have studied Shiga toxin 1 entry into enterohemorrhagic E. coli-infected intestinal epithelial cells and found that bacteria stimulate Shiga toxin 1 macropinocytosis through actin remodeling. This enterohemorrhagic E. coli-caused macropinocytosis occurs through a nonmuscle myosin II and cell division control 42 (Cdc42)-dependent mechanism. Macropinocytosis of Shiga toxin 1 is followed by its transcytosis to the basolateral environment, a step that is necessary for its systemic spread. Inhibition of Shiga toxin 1 macropinocytosis significantly decreases toxin uptake by intestinal epithelial cells and in this way provides an attractive, antibiotic-independent strategy for prevention of the harmful consequences of enterohemorrhagic E. coli infection.
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Affiliation(s)
- Valeriy Lukyanenko
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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17
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Abstract
Shiga toxin-producing Escherichia coli is a contaminant of food and water that in humans causes a diarrheal prodrome followed by more severe disease of the kidneys and an array of symptoms of the central nervous system. The systemic disease is a complex referred to as diarrhea-associated hemolytic uremic syndrome (D+HUS). D+HUS is characterized by thrombocytopenia, microangiopathic hemolytic anemia, and acute renal failure. This review focuses on the renal aspects of D+HUS. Current knowledge of this renal disease is derived from a combination of human samples, animal models of D+HUS, and interaction of Shiga toxin with isolated renal cell types. Shiga toxin is a multi-subunit protein complex that binds to a glycosphingolipid receptor, Gb3, on select eukaryotic cell types. Location of Gb3 in the kidney is predictive of the sites of action of Shiga toxin. However, the toxin is cytotoxic to some, but not all cell types that express Gb3. It also can cause apoptosis or generate an inflammatory response in some cells. Together, this myriad of results is responsible for D+HUS disease.
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Affiliation(s)
- Tom G Obrig
- Department of Microbiology and Immunology, School of Medicine, University of Maryland, 685 W. Baltimore St., HSF I Suite 380, Baltimore, MD 21201, USA; ; Tel.: +1-410-706-6917
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18
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Endocytosis and retrograde transport of Shiga toxin. Toxicon 2010; 56:1181-5. [DOI: 10.1016/j.toxicon.2009.11.021] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Accepted: 11/17/2009] [Indexed: 01/22/2023]
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19
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Shiga toxins: intracellular trafficking to the ER leading to activation of host cell stress responses. Toxins (Basel) 2010; 2:1515-35. [PMID: 22069648 PMCID: PMC3153247 DOI: 10.3390/toxins2061515] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 05/18/2010] [Accepted: 06/01/2010] [Indexed: 12/25/2022] Open
Abstract
Despite efforts to improve hygenic conditions and regulate food and drinking water safety, the enteric pathogens, Shiga toxin-producing Escherichia coli (STEC) and Shigella dysenteriae serotype 1 remain major public health concerns due to widespread outbreaks and the severity of extra-intestinal diseases they cause, including acute renal failure and central nervous system complications. Shiga toxins are the key virulence factors expressed by these pathogens mediating extra-intestinal disease. Delivery of the toxins to the endoplasmic reticulum (ER) results in host cell protein synthesis inhibition, activation of the ribotoxic stress response, the ER stress response, and in some cases, the induction of apoptosis. Intrinsic and/or extrinsic apoptosis inducing pathways are involved in executing cell death following intoxication. In this review we provide an overview of the current understanding Shiga toxin intracellular trafficking, host cellular responses to the toxin and ER stress-induced apoptosis with an emphasis on recent findings.
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20
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Johannes L, Römer W. Shiga toxins--from cell biology to biomedical applications. Nat Rev Microbiol 2009; 8:105-16. [PMID: 20023663 DOI: 10.1038/nrmicro2279] [Citation(s) in RCA: 352] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Shiga toxin-producing Escherichia coli is an emergent pathogen that can induce haemolytic uraemic syndrome. The toxin has received considerable attention not only from microbiologists but also in the field of cell biology, where it has become a powerful tool to study intracellular trafficking. In this Review, we summarize the Shiga toxin family members and their structures, receptors, trafficking pathways and cellular targets. We discuss how Shiga toxin affects cells not only by inhibiting protein biosynthesis but also through the induction of signalling cascades that lead to apoptosis. Finally, we discuss how Shiga toxins might be exploited in cancer therapy and immunotherapy.
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Affiliation(s)
- Ludger Johannes
- Institut Curie - Centre de Recherche and CNRS UMR144, Traffic, Signalling and Delivery Laboratory, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
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21
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Croxen MA, Finlay BB. Molecular mechanisms of Escherichia coli pathogenicity. Nat Rev Microbiol 2009; 8:26-38. [DOI: 10.1038/nrmicro2265] [Citation(s) in RCA: 668] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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22
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McKenzie J, Johannes L, Taguchi T, Sheff D. Passage through the Golgi is necessary for Shiga toxin B subunit to reach the endoplasmic reticulum. FEBS J 2008; 276:1581-95. [PMID: 19220458 DOI: 10.1111/j.1742-4658.2009.06890.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Both Shiga holotoxin and the isolated B subunit, navigate a retrograde pathway from the plasma membrane to the endoplasmic reticulum (ER) of mammalian cells to deliver catalytic A subunits into the cytosol. This route passes through early/recycling endosomes and then through the Golgi. Although passage through the endosomes takes only 30 min, passage through the Golgi is much slower, taking hours. This suggests that Golgi passage is a key step in retrograde traffic. However, there is no empirical data demonstrating that Golgi passage is required for the toxins to enter the ER. In fact, an alternate pathway bypassing the Golgi is utilized by SV40 virus. Here we find that blocking Shiga toxin B access to the entire Golgi with AlF(4)(-) treatment, temperature block or subcellular surgery prevented Shiga toxin B from reaching the ER. This suggests that there is no direct endosome to ER route available for retrograde traffic. Curiously, when Shiga toxin B was trapped in endosomes, it entered the cytosol directly from the endosomal compartment. Our results suggest that trafficking through the Golgi apparatus is required for Shiga toxin B to reach the ER and that diversion into the Golgi may prevent toxin escape from endosomes into the cytosol.
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Affiliation(s)
- Jenna McKenzie
- Department of Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-2600, USA
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