protein homooligomerization / transferase activity / nucleotide binding / extracellular region / identical protein binding / metal ion binding 類似検索 - 分子機能
ジャーナル: Nat Commun / 年: 2022 タイトル: Cryo-EM structures of the translocational binary toxin complex CDTa-bound CDTb-pore from Clostridioides difficile. 著者: Akihiro Kawamoto / Tomohito Yamada / Toru Yoshida / Yusui Sato / Takayuki Kato / Hideaki Tsuge / 要旨: Some bacteria express a binary toxin translocation system, consisting of an enzymatic subunit and translocation pore, that delivers enzymes into host cells through endocytosis. The most clinically ...Some bacteria express a binary toxin translocation system, consisting of an enzymatic subunit and translocation pore, that delivers enzymes into host cells through endocytosis. The most clinically important bacterium with such a system is Clostridioides difficile (formerly Clostridium). The CDTa and CDTb proteins from its system represent important therapeutic targets. CDTb has been proposed to be a di-heptamer, but its physiological heptameric structure has not yet been reported. Here, we report the cryo-EM structure of CDTa bound to the CDTb-pore, which reveals that CDTa binding induces partial unfolding and tilting of the first CDTa α-helix. In the CDTb-pore, an NSS-loop exists in 'in' and 'out' conformations, suggesting its involvement in substrate translocation. Finally, 3D variability analysis revealed CDTa movements from a folded to an unfolded state. These dynamic structural information provide insights into drug design against hypervirulent C. difficile strains.