ジャーナル: Sci Adv / 年: 2019 タイトル: Common architecture of Tc toxins from human and insect pathogenic bacteria. 著者: F Leidreiter / D Roderer / D Meusch / C Gatsogiannis / R Benz / S Raunser / 要旨: 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 ...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.
A: Insecticidal toxin protein TcdA4 B: Insecticidal toxin protein TcdA4 C: Insecticidal toxin protein TcdA4 D: Insecticidal toxin protein TcdA4 E: Insecticidal toxin protein TcdA4