| 1. |
- Kinsolving, Julia, et al.
(författare)
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Structural and functional insight into the interaction of Clostridioides difficile toxin B and FZD7
- 2024
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Ingår i: Cell Reports. - 2211-1247. ; 43:2
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Tidskriftsartikel (refereegranskat)abstract
- The G protein -coupled receptors of the Frizzled (FZD) family, in particular FZD1,2,7, are receptors that are exploited by Clostridioides difficile toxin B (TcdB), the major virulence factor responsible for pathogenesis associated with Clostridioides difficile infection. We employ a live -cell assay examining the affinity between full-length FZDs and TcdB. Moreover, we present cryoelectron microscopy structures of TcdB alone and in complex with full-length FZD7, which reveal that large structural rearrangements of the combined repetitive polypeptide domain are required for interaction with FZDs and other TcdB receptors, constituting a first step for receptor recognition. Furthermore, we show that bezlotoxumab, an FDA -approved monoclonal antibody to treat Clostridioides difficile infection, favors the apo-TcdB structure and thus disrupts binding with FZD7. The dynamic transition between the two conformations of TcdB also governs the stability of the pore -forming region. Thus, our work provides structural and functional insight into how conformational dynamics of TcdB determine receptor binding.
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| 2. |
- Kosenina, Sara, 1993-, et al.
(författare)
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Crystal structure of the catalytic domain of BoNT/X in complex with its substrate, VAMP2
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Botulinum neurotoxins (BoNTs) are the deadliest toxins known to man but are at the same time being used for the treatment of an increasing number of medical conditions. BoNTs are zinc proteases that act in presynaptic cholinergic motoneurons by cleaving SNARE proteins, hence inhibiting neurotransmission. Structural information on the BoNT catalytic domain is crucial for a detailed understanding of their substrate specificity and binding mechanism.Here we report the 1.85 Å crystal structure of the catalytic light chain of BoNT/X in complex with its substrate, VAMP2. The structure sheds light on the sites important for VAMP2 binding and will help in the engineering of novel therapeutic toxins with altered and improved substrate specificity.
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| 3. |
- Košenina, Sara, 1993-, et al.
(författare)
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The cryo-EM structure of the BoNT/Wo-NTNH complex reveals two immunoglobulin-like domains
- 2024
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Ingår i: The FEBS Journal. - 1742-464X .- 1742-4658. ; 291:4, s. 676-689
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Tidskriftsartikel (refereegranskat)abstract
- The botulinum neurotoxin-like toxin from Weissella oryzae (BoNT/Wo) is one of the BoNT-like toxins recently identified outside of the Clostridium genus. We show that, like the canonical BoNTs, BoNT/Wo forms a complex with its non-toxic non-hemagglutinin (NTNH) partner, which in traditional BoNT serotypes protects the toxin from proteases and the acidic environment of the hosts' guts. We here report the cryo-EM structure of the 300 kDa BoNT/Wo-NTNH/Wo complex together with pH stability studies of the complex. The structure reveals molecular details of the toxin's interactions with its protective partner. The overall structural arrangement is similar to other reported BoNT-NTNH complexes, but NTNH/Wo uniquely contains two extra bacterial immunoglobulin-like (Big) domains on the C-terminus. Although the function of these Big domains is unknown, they are structurally most similar to bacterial proteins involved in adhesion to host cells. In addition, the BoNT/Wo protease domain contains an internal disulfide bond not seen in other BoNTs. Mass photometry analysis revealed that the BoNT/Wo-NTNH/Wo complex is stable under acidic conditions and may dissociate at neutral to basic pH. These findings established that BoNT/Wo-NTNH/Wo shares the general fold of canonical BoNT–NTNH complexes. The presence of unique structural features suggests that it may have an alternative mode of activation, translocation and recognition of host cells, raising interesting questions about the activity and the mechanism of action of BoNT/Wo as well as about its target environment, receptors and substrates.
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| 4. |
- Persson Košenina, Sara, 1993-
(författare)
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Botulinum neurotoxins
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Botulinum neurotoxins (BoNTs) are the most potent toxins known to man, with less than 1 μg of pure toxin being enough to kill an adult man. Despite the high toxicity, BoNTs are widely used in cosmetics and in medicine for the treatment of an increasing number of medical conditions.BoNTs have a conserved structure that consists of three domains (a receptor binding, translocation, and catalytic domain). The receptor binding domain is responsible for binding to neuronal receptors, the translocation domain is a delivery vehicle that transports the catalytic domain into the cytosol, where the latter cleaves its target - proteins of the SNARE family, inhibiting neurotransmitter release and consequently causing muscle paralysis.BoNTs are produced by the bacteria Clostridium botulinum together with several other accessory proteins, which are responsible for shielding BoNTs in the harsh environment of the target gastrointestinal tract and assisting them in crossing the epithelial barrier between the gastrointestinal tract and general circulation.Several BoNT serotypes (A-G) have been identified over the years. Additionally, several BoNT-like toxins have been identified in non-Clostridial types of bacteria. Namely, these proteins are BoNT/Wo, BoNT/En and PMP1.In this thesis, we present six papers, where we studied both the canonical BoNTs and the new BoNT-like toxins as well as their accessory proteins using structural biology techniques, such as X-ray crystallography and cryo-EM. Elucidating the structures of these proteins is crucial for understanding their function and mechanism of action.
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