Download MendeleyCryo-EM structures reveal translocational unfolding in the clostridial binary iota toxin complex.
Yamada, T., Yoshida, T., Kawamoto, A., Mitsuoka, K., Iwasaki, K., Tsuge, H.(2020) Nat Struct Mol Biol 27: 288-296
- PubMed: 32123390
- DOI: https://doi.org/10.1038/s41594-020-0388-6
- Primary Citation of Related Structures:
6KLO, 6KLW, 6KLX - PubMed Abstract:
The iota toxin produced by Clostridium perfringens type E is a binary toxin comprising two independent polypeptides: Ia, an ADP-ribosyltransferase, and Ib, which is involved in cell binding and translocation of Ia across the cell membrane. Here we report cryo-EM structures of the translocation channel Ib-pore and its complex with Ia. The high-resolution Ib-pore structure demonstrates a similar structural framework to that of the catalytic ϕ-clamp of the anthrax protective antigen pore. However, the Ia-bound Ib-pore structure shows a unique binding mode of Ia: one Ia binds to the Ib-pore, and the Ia amino-terminal domain forms multiple weak interactions with two additional Ib-pore constriction sites. Furthermore, Ib-binding induces tilting and partial unfolding of the Ia N-terminal α-helix, permitting its extension to the ϕ-clamp gate. This new mechanism of N-terminal unfolding is crucial for protein translocation.
Organizational Affiliation:
Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, Japan.
