scholarly journals Binding and Internalization of Clostridium perfringens Iota-Toxin in Lipid Rafts

2004 ◽  
Vol 72 (6) ◽  
pp. 3267-3275 ◽  
Author(s):  
Masahiro Nagahama ◽  
Akiwo Yamaguchi ◽  
Tohko Hagiyama ◽  
Noriko Ohkubo ◽  
Keiko Kobayashi ◽  
...  

ABSTRACT Clostridium perfringens iota-toxin is a binary toxin composed of an enzymatic component (Ia) and a binding component (Ib). The oligomer of Ib formed in membranes induces endocytosis. We examined the binding and internalization of Ib by using Cy3-labeled Ib. Labeled Ib was retained at the membranes of MDCK cells for 60 min of incubation at 37°C, and later it was detected in cytoplasmic vesicles. To determine whether Ib associates with lipid rafts, we incubated MDCK cells with Ib at 4 or 37°C and fractionated the Triton-insoluble membranes. An Ib complex of 500 kDa was localized at 37°C to the insoluble fractions that fulfilled the criteria of lipid rafts, but it did not form at 4°C. The amount of complex in the raft fraction reached a maximum after 60 min of incubation at 37°C. When the cells that were preincubated with Ib at 4°C were incubated at 37°C, the complex was detected in the raft fraction. The treatment of MDCK cells with methyl-β-cyclodextrin reduced the localization of the Ib complex to the rafts and the rounding of the cells induced by Ia plus Ib. When 125I-labeled Ia was incubated with the cells in the presence of Ib at 37°C, it was localized in the raft fraction. Surface plasmon resonance analysis revealed that Ia binds to the oligomer of Ib. We conclude that Ib binds to a receptor in membranes and then moves to rafts and that Ia bound to the oligomer of Ib formed in the rafts is internalized.


Toxins ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 405 ◽  
Author(s):  
Masahiro Nagahama ◽  
Masaya Takehara ◽  
Keiko Kobayashi

Iota toxin produced by Clostridium perfringens is a binary, actin ADP-ribosylating toxin that is organized into the enzymatically active component Ia and the binding component Ib. Lipolysis-stimulated lipoprotein receptor (LSR) has been identified as a cellular receptor of Ib. Here, we investigated the functional interaction between Ib and LSR, where siRNA for LSR blocked the toxin-mediated cytotoxicity and the binding of Ib. The addition of Ib to LSR-green fluorescence protein (GFP)-transfected cells at 4 °C resulted in colocalization with LSR and Ib on the cell surface. Upon transfer of the cells from 4 °C to 37 °C, LSR and Ib were internalized and observed in cytoplasmic vesicles. When the cells were incubated with Ib at 37 °C and fractionated using the Triton-insoluble membrane, Ib oligomer was localized in insoluble factions that fulfilled the criteria of lipid rafts, and LSR was clustered in lipid rafts. To examine the interaction between N-terminal extracellular region of LSR and Ib, we constructed a series of LSR N-terminal deletions. Ten amino acids residues can be deleted from this end without any reduction of Ib binding. However, deletion of 15 N-terminal residues drastically reduces its ability to bind Ib. These results demonstrate that Ib binds to the LSR N-terminal 10 to 15 residues and endocytoses into trafficking endosomes together with LSR.



2009 ◽  
Vol 77 (11) ◽  
pp. 5139-5148 ◽  
Author(s):  
Masahiro Nagahama ◽  
Tohko Hagiyama ◽  
Takashi Kojima ◽  
Kouhei Aoyanagi ◽  
Chihiro Takahashi ◽  
...  

ABSTRACT Clostridium botulinum C2 toxin is a binary toxin composed of an enzymatic component (C2I) and a binding component (C2II). The activated binding component (C2IIa) forms heptamers, and the oligomer with C2I is taken up by receptor-mediated endocytosis. We investigated the binding and internalization of C2IIa in cells. The C2IIa monomer formed oligomers on lipid rafts in membranes of MDCK cells. Methyl-beta-cyclodextrin inhibited the binding of C2IIa and the rounding of the cells induced by C2I plus C2IIa. C2I was localized to the rafts in the presence, but not the absence, of C2IIa. Surface plasmon resonance analysis revealed that C2I bound to the oligomer of C2IIa, but not the monomer of C2IIa. C2I and C2IIa were rapidly internalized in the cells. LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor, inhibited the internalization of C2IIa in the cells and the rounding activity in the presence of C2I plus C2IIa. Incubation of the cells with C2I plus C2IIa resulted in the activation of PI3K and in phosphorylation of phosphoinositide-dependent kinase 1 and protein kinase B/Akt (Akt), but that with C2IIa alone did not. Akt inhibitor X, an Akt phosphorylation inhibitor, inhibited the rounding activity but not the internalization of C2IIa. The results suggest that the binding of C2I to the oligomer of C2IIa on rafts triggers the activation of the PI3K-Akt signaling pathway and, in turn, the initiation of endocytosis.



2002 ◽  
Vol 70 (4) ◽  
pp. 1909-1914 ◽  
Author(s):  
Masahiro Nagahama ◽  
Koichi Nagayasu ◽  
Keiko Kobayashi ◽  
Jun Sakurai

ABSTRACT Clostridium perfringens iota-toxin is a binary toxin consisting of two individual proteins, the binding component (Ib) and the enzyme component (Ia). Wild-type Ib bound to Vero cells at 4 and 37°C and formed oligomers at 37°C but not at 4°C. The Ib-induced K+ release from the cells was dependent on the oligomer formation of Ib in the cells, but the oligomer formation did not induce rounding activity or cytotoxicity. After incubation of the cells with recombinant Ib (rIb) at 37°C, the Ib oligomer in the cell became resistant to pronase treatment with time, but the Ib monomer was sensitive to the treatment. Furthermore, treatment of Vero cells with rIb in the presence of bafilomycin, methylamine, or ethylamine resulted in accumulation of the oligomer in the cells but had no effect on K+ release. Moreover, incubation with Ib plus Ia in the presence of these agents caused no rounding in the cells. These observations suggest that Ib binds to Vero cells, itself oligomerizing to form ion-permeable channels and that the formation of oligomer then induces endocytosis.



mBio ◽  
2013 ◽  
Vol 4 (3) ◽  
Author(s):  
Panagiotis Papatheodorou ◽  
Daniel Hornuss ◽  
Thilo Nölke ◽  
Sarah Hemmasi ◽  
Jan Castonguay ◽  
...  

ABSTRACT Clostridium difficile is the leading cause of antibiotics-associated diarrhea and pseudomembranous colitis. Hypervirulent C. difficile strains produce the binary actin-ADP-ribosylating toxin CDT (C. difficile transferase), in addition to the Rho-glucosylating toxins A and B. We recently identified the lipolysis-stimulated lipoprotein receptor (LSR) as the host receptor that mediates uptake of CDT into target cells. Here we investigated in H1-HeLa cells, which ectopically express LSR, the influence of CDT on the plasma membrane distribution of the receptor. We found by fluorescence microscopy that the binding component of CDT (CDTb) induces clustering of LSR into subcompartments of the plasma membrane. Detergent extraction of cells treated with CDTb, followed by sucrose gradient fractionation, uncovered accumulation of LSR in detergent-resistant membranes (DRMs) that contained typical marker proteins of lipid rafts. Membrane cholesterol depletion with methyl-β-cyclodextrin inhibited the association of LSR with DRMs upon addition of CDTb. The receptor-binding domain of CDTb also triggered LSR clustering into DRMs. CDTb-triggered clustering of LSR into DRMs could be confirmed in Caco-2 cells. Our data suggest that CDT forces its receptor to cluster into lipid rafts and that oligomerization of the B component might enhance but is not essential for this process. IMPORTANCE C. difficile binary toxin CDT is a member of the iota-like, actin ADP-ribosylating toxin family. The mechanism that mediates endocytic uptake of these toxins still remains elusive. Previous studies highlighted the importance of lipid rafts for oligomerization of the binding component of these toxins and for cell entry. Recently, the host cell receptor for this toxin family, namely, the lipolysis-stimulated lipoprotein receptor (LSR), has been identified. Our study now demonstrates that the binding component of CDT (CDTb) induces clustering of LSR into lipid rafts. Importantly, LSR clustering is efficiently induced also by the receptor-binding domain of CDTb, suggesting that oligomerization of the B component of CDT is not the main trigger of this process. The current work extends our knowledge on the cooperative play between iota-like toxins and their receptor.



Toxins ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 721
Author(s):  
Masahiro Nagahama ◽  
Keiko Kobayashi ◽  
Masaya Takehara

Iota-toxin from Clostridium perfringens type E is a binary toxin composed of two independent proteins: actin-ADP-ribosylating enzyme component, iota-a (Ia), and binding component, iota-b (Ib). Ib binds to target cell receptors and mediates the internalization of Ia into the cytoplasm. Extracellular lysosomal enzyme acid sphingomyelinase (ASMase) was previously shown to facilitate the internalization of iota-toxin. In this study, we investigated how lysosomal cathepsin promotes the internalization of iota-toxin into target cells. Cysteine protease inhibitor E64 prevented the cytotoxicity caused by iota-toxin, but aspartate protease inhibitor pepstatin-A and serine protease inhibitor AEBSF did not. Knockdown of lysosomal cysteine protease cathepsins B and L decreased the toxin-induced cytotoxicity. E64 suppressed the Ib-induced ASMase activity in extracellular fluid, showing that the proteases play a role in ASMase activation. These results indicate that cathepsin B and L facilitate entry of iota-toxin via activation of ASMase.



1990 ◽  
Vol 194 (1) ◽  
pp. 237-241 ◽  
Author(s):  
Stefan MAUSS ◽  
Christine CHAPONNIER ◽  
Ingo JUST ◽  
Klaus AKTORIES ◽  
Giulio GABBIANI


1998 ◽  
Vol 142 (1) ◽  
pp. 69-84 ◽  
Author(s):  
A.K. Kenworthy ◽  
M. Edidin

Membrane microdomains (“lipid rafts”) enriched in glycosylphosphatidylinositol (GPI)-anchored proteins, glycosphingolipids, and cholesterol have been implicated in events ranging from membrane trafficking to signal transduction. Although there is biochemical evidence for such membrane microdomains, they have not been visualized by light or electron microscopy. To probe for microdomains enriched in GPI- anchored proteins in intact cell membranes, we used a novel form of digital microscopy, imaging fluorescence resonance energy transfer (FRET), which extends the resolution of fluorescence microscopy to the molecular level (<100 Å). We detected significant energy transfer between donor- and acceptor-labeled antibodies against the GPI-anchored protein 5′ nucleotidase (5′ NT) at the apical membrane of MDCK cells. The efficiency of energy transfer correlated strongly with the surface density of the acceptor-labeled antibody. The FRET data conformed to theoretical predictions for two-dimensional FRET between randomly distributed molecules and were inconsistent with a model in which 5′ NT is constitutively clustered. Though we cannot completely exclude the possibility that some 5′ NT is in clusters, the data imply that most 5′ NT molecules are randomly distributed across the apical surface of MDCK cells. These findings constrain current models for lipid rafts and the membrane organization of GPI-anchored proteins.



JOM ◽  
2015 ◽  
Vol 67 (11) ◽  
pp. 2494-2501
Author(s):  
Jenifer K. Tucker ◽  
Mark L. Richter ◽  
Cindy L. Berrie


2009 ◽  
Vol 77 (12) ◽  
pp. 5593-5601 ◽  
Author(s):  
Hanna Hilger ◽  
Sascha Pust ◽  
Guido von Figura ◽  
Eva Kaiser ◽  
Bradley G. Stiles ◽  
...  

ABSTRACT Mono-ADP ribosylation of actin by bacterial toxins, such as Clostridium perfringens iota or Clostridium botulinum C2 toxins, results in rapid depolymerization of actin filaments and cell rounding. Here we report that treatment of African green monkey kidney (Vero) cells with iota toxin resulted in delayed caspase-dependent death. Unmodified actin did not reappear in toxin-treated cells, and enzyme-active toxin was detectable in the cytosol for at least 24 h. C2 toxin showed comparable, long-lived effects in cells, while a C2 toxin control lacking ADP-ribosyltransferase activity did not induce cell death. To address whether the remarkable stability of the iota and C2 toxins in cytosol was crucial for inducing cell death, we treated cells with C/SpvB, the catalytic domain of Salmonella enterica SpvB. Although C/SpvB also mono-ADP ribosylates actin as do the iota and C2 toxins, cells treated with a cell-permeating C/SpvB fusion toxin became rounded but recovered and remained viable. Moreover, unmodified actin reappeared in these cells, and ADP-ribosyltransferase activity due to C/SpvB was not detectable in the cytosol after 24 h, a result most likely due to degradation of C/SpvB. Repeated application of C/SpvB prevented recovery of cells and reappearance of unmodified actin. In conclusion, a complete but transient ADP ribosylation of actin was not sufficient to trigger apoptosis, implying that long-term stability of actin-ADP-ribosylating toxins, such as iota and C2, in the cytosol is crucial for inducing delayed, caspase-dependent cell death.



Sign in / Sign up

Export Citation Format

Share Document