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Publication Abstract from PubMed

Tc toxins use a syringe-like mechanism to penetrate the membrane and translocate toxic enzymes into the host cytosol. They are composed of three components: TcA, TcB, and TcC. Low-resolution structures of TcAs from different bacteria suggest a considerable difference in their architecture and possibly in their mechanism of action. Here, we present high-resolution structures of five TcAs from insect and human pathogens, which show a similar overall composition and domain organization. Essential structural features, including a trefoil protein knot, are present in all TcAs, suggesting a common mechanism of action. All TcAs form functional pores and can be combined with TcB-TcC subunits from other species to form active chimeric holotoxins. We identified a conserved ionic pair that stabilizes the shell, likely operating as a strong latch that only springs open after destabilization of other regions. Our results provide new insights into the architecture and mechanism of the Tc toxin family.

Common architecture of Tc toxins from human and insect pathogenic bacteria.,Leidreiter F, Roderer D, Meusch D, Gatsogiannis C, Benz R, Raunser S Sci Adv. 2019 Oct 16;5(10):eaax6497. doi: 10.1126/sciadv.aax6497. eCollection, 2019 Oct. PMID:31663026^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.