Step-by-step maturation mechanism of the binary toxin pore revealed by cryo-EM analysis.

Authors

Tomohito Yamada, Ren Nakanishi, Yukihiko Sugita, Yuki Ninomiya, Toru Yoshida, Takeshi Noda, Hideaki Tsuge

Published in

Proceedings of the National Academy of Sciences of the United States of America. Volume 123. Issue 40. Pages e2627537123. Oct 06, 2026. Epub Sep 28, 2026.

Abstract

Membrane pore-forming proteins (PFPs) form ring-shaped membrane-translocating oligomers on membranes, contributing to infection, immunity, and cell death functions. Binary toxins produced by some bacteria consist of an enzymatic component that acts as a toxin and a membrane-binding component that forms a pore that delivers the enzymatic component into target cells. Cryoelectron microscopy (cryo-EM) has advanced our understanding of these translocation mechanisms by revealing several binary toxin complexes' structures. However, the mechanisms underlying the initial pore formation remain unclear. We determined the structures of several oligomeric forms of the membrane-binding component Ib of the iota toxin from Clostridium perfringens at various stages of pore formation. Structural comparisons revealed how the symmetrically arranged soluble oligomer (prepore) asymmetrically matures into a transmembrane oligomer (pore). These findings enhance our understanding of mechanisms of PFP and provide a structural basis for developing nanodevices using membrane pores.

PMID:
42804625
Bibliographic data and abstract were imported from PubMed on 29 Sep 2026.

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