The Host Cell Chaperone Hsp90 Is Essential for Translocation of the Binary Clostridium botulinum C2 Toxin into the Cytosol

Haug, Gerd; Leemhuis, Jost; Tiemann, Dirk; Meyer, Dieter; Aktories, Klaus; Barth, Holger

doi:10.1074/jbc.m303980200

Cited by 132 publications

(156 citation statements)

References 33 publications

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“…This hypothesis is strengthened by our recent observation that a cellular chaperone most likely mediates translocation and/or refolding of C2I. We found that heat shock protein Hsp90 is essential for uptake of active C2I from endosomes into the cytosol of cells (32). If C2I has to become unfolded for its translocation through endosomal membranes, FIG.…”

Section: Fig 6 Ph-dependent C2i Translocation Into the Cytosol Of Vmentioning

confidence: 50%

Clostridium botulinum C2 Toxin

Blöcker

Pohlmann

Haug

et al. 2003

Journal of Biological Chemistry

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The binary Clostridium botulinum C2 toxin consists of two individual proteins, the transport component C2II (80 kDa) and the enzyme component C2I, which ADPribosylates G-actin in the cytosol of cells. Trypsin-activated C2II (C2IIa) forms heptamers that bind to the cell receptor and mediate translocation of C2I from acidic endosomes into the cytosol of target cells. Here, we report that translocation of C2I across cell membranes is accompanied by pore formation of C2IIa. We used a radioactive rubidium release assay to detect C2IIa pores in the membranes of Chinese hamster ovary cells. Pore formation by C2IIa was dependent on the cellular C2 toxin receptor and an acidic pulse. Pores were formed when C2IIa was bound to cells at neutral pH and when cells were subsequently shifted to acidic medium (pH < 5.5), but no pores were detected when C2IIa was added to cells directly in acidic medium. Most likely, acidification induces a change from "pre-pore" to "pore" conformation of C2IIa, and formation of the pore conformation before membrane binding precludes insertion into membranes. When C2I was present during binding of C2IIa to cells prior to the acidification step, C2IIa-mediated rubidium release was decreased, suggesting that C2I interacted with the lumen of the C2IIa pore. A decrease of rubidium efflux was also detected when C2I was added to C2IIa-treated cells after the acidification step, suggesting that C2I interacted with C2IIa in its pore conformation. Moreover, C2I also interacted with C2IIa channels in artificial lipid membranes and blocked them partially. C2I was only translocated across the cell membrane when C2IIa plus C2I were bound to cells at neutral pH and subsequently shifted to acidic pH. When cell-bound C2IIa was exposed to acidic pH prior to C2I addition, only residual intoxication of cells was observed at high toxin concentrations, and binding of C2I to C2IIa was slightly decreased. Overall, C2IIa pores were essential but not sufficient for translocation of C2I. Intoxication of target cells with C2 toxin requires a strictly coordinated pH-dependent sequence of binding, pore formation by C2IIa, and translocation of C2I.

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Section: Fig 6 Ph-dependent C2i Translocation Into the Cytosol Of Vmentioning

confidence: 50%

Clostridium botulinum C2 Toxin

Blöcker

Pohlmann

Haug

et al. 2003

Journal of Biological Chemistry

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“…In addition, growth factors such as fibroblast growth factor (FGF)-1/2 (36) and certain protein toxins like diphtheria toxin appear to use HSP90 for their translocation into cytosol in non-APC (37,38). Moreover, HSP90 was recently shown to mediate dislocation of the cholera toxin A1 (CTA1) subunit from the ER into the cytosol.…”

Section: Discussionmentioning

confidence: 99%

Heat shock protein 90 (HSP90) contributes to cytosolic translocation of extracellular antigen for cross-presentation by dendritic cells

Imai¹,

Kato²,

Kajiwara³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

129

123

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In antigen (Ag) cross-presentation, dendritic cells (DCs) take up extracellular Ag and translocate them from the endosome to the cytosol for proteasomal degradation. The processed peptides can enter the conventional MHC I pathway. The molecules responsible for the translocation of Ag across the endosomal membrane into the cytosol are unknown. Here we demonstrate that heat shock protein 90 (HSP90) is critical for this step. Cross-presentation and -priming were decreased in both HSP90α-null DCs and mice. CD8α + DC apoptosis mediated by translocation of exogenous cytochrome c to the cytosol was also eliminated in HSP90α-null mice. Ag translocation into the cytosol was diminished in HSP90α-null DCs and in DCs treated with an HSP90 inhibitor. Internalized Ag was associated with HSP90 and translocated to the cytosol, a process abrogated by the HSP90 inhibitor. Ag within purified phagosomes was released in an HSP90-dependent manner. These results demonstrate the important role of HSP90 in cross-presentation by pulling endosomal Ag out into the cytosol.

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“…Specific inhibitors of Hsp90, such as geldanamycin or radicicol, effectively delay C2-, CDT-, or -induced cytotoxicity in various cell types by inhibiting, respectively, C2I, CDTa, or Ia entry into the cytosol. Interestingly, cytosolic entry of B. anthracis lethal toxin differs in that it is not affected by Hsp90 inhibitors (179), thereby suggesting distinct endosometo-cytosol translocation mechanisms for "A" components of this binary toxin family.…”

Section: Cell Entry and Intoxication "B" Binding To The Cellmentioning

confidence: 99%

“…4. Depiction of C2 intoxication via Hsp90, a process that is required for entry of C2I into the cytosol from acidified endosomes (179). A similar pathway is also used by toxin and CDT for intoxicating cells (178a).…”

Section: Cell Entry and Intoxication "B" Binding To The Cellmentioning

confidence: 99%

Binary Bacterial Toxins: Biochemistry, Biology, and Applications of CommonClostridiumandBacillusProteins

Barth

Aktories

Popoff

et al. 2004

Microbiol Mol Biol Rev

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371

388

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Certain pathogenic species of Bacillus and Clostridium have developed unique methods for intoxicating cells that employ the classic enzymatic “A-B” paradigm for protein toxins. The binary toxins produced by B. anthracis, B. cereus, C. botulinum, C. difficile, C. perfringens, and C. spiroforme consist of components not physically associated in solution that are linked to various diseases in humans, animals, or insects. The “B” components are synthesized as precursors that are subsequently activated by serine-type proteases on the targeted cell surface and/or in solution. Following release of a 20-kDa N-terminal peptide, the activated “B” components form homoheptameric rings that subsequently dock with an “A” component(s) on the cell surface. By following an acidified endosomal route and translocation into the cytosol, “A” molecules disable a cell (and host organism) via disruption of the actin cytoskeleton, increasing intracellular levels of cyclic AMP, or inactivation of signaling pathways linked to mitogen-activated protein kinase kinases. Recently, B. anthracis has gleaned much notoriety as a biowarfare/bioterrorism agent, and of primary interest has been the edema and lethal toxins, their role in anthrax, as well as the development of efficacious vaccines and therapeutics targeting these virulence factors and ultimately B. anthracis. This review comprehensively surveys the literature and discusses the similarities, as well as distinct differences, between each Clostridium and Bacillus binary toxin in terms of their biochemistry, biology, genetics, structure, and applications in science and medicine. The information may foster future studies that aid novel vaccine and drug development, as well as a better understanding of a conserved intoxication process utilized by various gram-positive, spore-forming bacteria

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The Host Cell Chaperone Hsp90 Is Essential for Translocation of the Binary Clostridium botulinum C2 Toxin into the Cytosol

Cited by 132 publications

References 33 publications

Clostridium botulinum C2 Toxin

Clostridium botulinum C2 Toxin

Heat shock protein 90 (HSP90) contributes to cytosolic translocation of extracellular antigen for cross-presentation by dendritic cells

Binary Bacterial Toxins: Biochemistry, Biology, and Applications of CommonClostridiumandBacillusProteins

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