Large clostridial glycosylating toxins modifying small GTPases

Genth, Harald; Just, Ingo

doi:10.1016/b978-0-12-800188-2.00016-1

Cited by 3 publications

(3 citation statements)

References 143 publications

(188 reference statements)

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“…Several members of the LDL receptor family (including LRP1 and LRP5/6) have been presented to bind FZD receptors and to act as Wnt co-receptors ( Zilberberg et al, 2004 ; Dieckmann et al, 2010 ). The observations of this study favor a two receptor model of the cellular uptake of TcdB ( Genth and Just, 2015 ) ( Figure 4 ): TcdB binds to FZD1/2/7, CSPG4, and PVRL3, either of which receptors exhibits (if any) a low internalization rate. Initial (low affinity) binding allows enrichment of TcdB at the surface of ISEMFs or cultured colonic epithelial cells.…”

Section: Discussionsupporting

confidence: 59%

Expression and (Lacking) Internalization of the Cell Surface Receptors of Clostridioides difficile Toxin B

et al. 2018

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Toxin-producing strains of Clostridioides difficile and Clostridium perfringens cause infections of the gastrointestinal tract in humans and ruminants, with the toxins being major virulence factors, essential for the infection, and responsible for the onset of severe symptoms. C. difficile toxin A (TcdA) and toxin B (TcdB), and the large cytotoxin (TpeL) from C. perfringens are single chain bacterial protein toxins with an AB-like toxin structure. The C-terminal delivery domain mediates cell entry of the N-terminal glycosyltransferase domain by receptor-mediated endocytosis. Several cell surface proteins have been proposed to serve as toxin receptors, including chondroitin-sulfate proteoglycan 4 (CSPG4), poliovirus receptor-like 3 (PVRL3), and frizzled-1/2/7 (FZD1/2/7) for TcdB and LDL-receptor-related protein-1 (LRP1) for TpeL. The expression of the TcdB receptors was investigated in human intestinal organoids (HIOs) and in cultured cell lines. HIOs from four human donors exhibited a comparable profile of receptor expression, with PVRL3, LRP1, and FZD7 being expressed and CSPG4 and FZD2 not being expressed. In human epithelial Caco-2 cells and HT29 cells as well as in immortalized murine fibroblasts, either receptor FZD2/7, CSPG4, PVRL3, and LRP1 was expressed. The question whether the toxins take advantage of the normal turnover of their receptors (i.e., constitutive endocytosis and recycling) from the cell surface or whether the toxins activity induce the internalization of their receptors has not yet been addressed. For the analysis of receptor internalization, temperature-induced uptake of biotinylated toxin receptors into immortalized mouse embryonic fibroblasts (MEFs) and Caco-2 cells was exploited. Solely LRP1 exhibited constitutive endocytosis from the plasma membrane to the endosome, which might be abused by TpeL (and possibly TcdB as well) for cell entry. Furthermore, internalization of CSPG4, PVRL3, FZD2, and FZD7 was observed neither in MEFs nor in Caco-2 cells. FZD2/7, CSPG4, and PVRL3 did thus exhibit no constitutive recycling. The presence of TcdB and the p38 activation induced by anisomycin were not able to induce or enhance CSPG4 or PVRL3 uptake in MEFs. In conclusion, FZD2/7, CSPG4, and PVRL3 seem to serve as cell surface binding receptors rather than internalizing receptors of TcdB.

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Section: Discussionsupporting

confidence: 59%

Expression and (Lacking) Internalization of the Cell Surface Receptors of Clostridioides difficile Toxin B

et al. 2018

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“…Using uridine‐diphosphate (UDP)‐glucose or UDP‐ N ‐acetyl‐glucosamine as cosubstrate, LCGTs catalyse glucosylation or glucosamination of small guanosine triphosphatases (GTPases) from the Rho (Ras homologue) and/or Ras (rat sarcoma) families at the conserved threonine Thr35/37 yielding inactive signal molecules (Guttenberg et al, 2012; Hofmann, Rex, Aktories, & Just, 1996; Jank & Aktories, 2008; Just, Selzer, et al, 1995; Just, Wilm, et al, 1995; Nagahama et al, 2011; Popoff et al, 1996; Selzer et al, 1996). Each LCGT interacts with distinct sets of GTPases (Genth et al, 2014; Genth, Dreger, Huelsenbeck, & Just, 2008; Genth & Just, 2015; Jank & Aktories, 2008; Just & Gerhard, 2004; Zeiser, Gerhard, Just, & Pich, 2013). Thereby, TcsL mainly targets Rac (Ras‐related C3 botulinum enzyme substrate from the Rho family) and Ras proteins and induces actin cytoskeleton depolymerisation and cytotoxicity (Genth et al, 2014; Genth & Just, 2011).…”

Section: Lesson From Clostridium Sordellii Lethal Toxin: a Toxin Addrmentioning

confidence: 99%

Bacterial intracellularly active toxins: Membrane localisation of the active domain

Varela-Chavez

Blondel

Popoff

2020

Cellular Microbiology

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Numerous bacterial toxins exert their activity by inactivating or modulating a specific intracellular host target. For this purpose, these toxins have developed efficient strategies to overcome the different host cell defences including specific binding to cell surface, internalisation, passage through the endosome or plasma membrane, exploiting intracellular trafficking and addressing to intracellular targets. Several intracellularly active toxins deliver an active domain into the cytosol that interacts with a target localised to the inner face of the plasma membrane. Thus, the large clostridial glucosylating toxins (LCGTs) target Rho/Ras-GTPases, certain virulence factors of Gram negative bacteria, Rho-GTPases, while Pasteurella multocida toxin (PMT) targets trimeric G-proteins. Others such as botulinum neurotoxins and tetanus neurotoxin have their substrate on synaptic vesicle membrane. LCGTs, PMT, and certain virulence factors from Vibrio sp. show a particular structure constituted of a four-helix bundle membrane (4HBM) protruding from the catalytic site that specifically binds to the membrane phospholipids and then trap the catalytic domain at the proximity of the membrane anchored substrate. Structural and functional analysis indicate that the 4HBM tip of the Clostridium sordellii lethal toxin (TcsL) from the LCGT family contain two loops forming a cavity that mediates the binding to phospholipids and more specifically to phosphatidylserine. K E Y W O R D S Bacterial virulence factors, cell membrane, large clostridial glucosylating toxins, MARTX toxins, Pasteurella multocida toxin, phospholipids, Rho/Ras-GTPases

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“…While C. difficile and C. sordellii toxins use UDP-glucose as a cofactor, TcnA and TpeL prefer UDP- N -acetylglucosamine [ 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. Each LCGT interacts with distinct sets of GTPases [ 7 , 8 , 17 , 18 , 19 , 20 ]. Thereby, TcsL mainly targets Rac and Ras proteins and induces actin cytoskeleton depolymerization and cytotoxicity [ 8 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

The Tip of the Four N-Terminal α-Helices of Clostridium sordellii Lethal Toxin Contains the Interaction Site with Membrane Phosphatidylserine Facilitating Small GTPases Glucosylation

Chavez

Haustant

Baron

et al. 2016

Toxins

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Clostridium sordellii lethal toxin (TcsL) is a powerful virulence factor responsible for severe toxic shock in man and animals. TcsL belongs to the large clostridial glucosylating toxin (LCGT) family which inactivates small GTPases by glucosylation with uridine-diphosphate (UDP)-glucose as a cofactor. Notably, TcsL modifies Rac and Ras GTPases, leading to drastic alteration of the actin cytoskeleton and cell viability. TcsL enters cells via receptor-mediated endocytosis and delivers the N-terminal glucosylating domain (TcsL-cat) into the cytosol. TcsL-cat was found to preferentially bind to phosphatidylserine (PS)-containing membranes and to increase the glucosylation of Rac anchored to the lipid membrane. We have previously reported that the N-terminal four helical bundle structure (1–93 domain) recognizes a broad range of lipids, but that TcsL-cat specifically binds to PS and phosphatidic acid. Here, we show using mutagenesis that the PS binding site is localized on the tip of the four-helix bundle which is rich in positively-charged amino acids. Residues Y14, V15, F17, and R18 on loop 1, between helices 1 and 2, in coordination with R68 from loop 3, between helices 3 and 4, form a pocket which accommodates L-serine. The functional PS-binding site is required for TcsL-cat binding to the plasma membrane and subsequent cytotoxicity. TcsL-cat binding to PS facilitates a high enzymatic activity towards membrane-anchored Ras by about three orders of magnitude as compared to Ras in solution. The PS-binding site is conserved in LCGTs, which likely retain a common mechanism of binding to the membrane for their full activity towards membrane-bound GTPases.

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Large clostridial glycosylating toxins modifying small GTPases

Cited by 3 publications

References 143 publications

Expression and (Lacking) Internalization of the Cell Surface Receptors of Clostridioides difficile Toxin B

Expression and (Lacking) Internalization of the Cell Surface Receptors of Clostridioides difficile Toxin B

Bacterial intracellularly active toxins: Membrane localisation of the active domain

The Tip of the Four N-Terminal α-Helices of Clostridium sordellii Lethal Toxin Contains the Interaction Site with Membrane Phosphatidylserine Facilitating Small GTPases Glucosylation

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