Pore formation by the CDTb component of the Clostridioides difficile binary toxin is Ca²⁺-dependent.

ABSTRACT: Clostridioides difficile infection (CDI) is one of the five most urgent bacterial threats in the United States. Furthermore, hypervirulent CDI strains express a third toxin termed the C. difficile binary toxin (CDT), and its molecular mechanism for entering host cells is not fully elucidated. Like other AB-type binary toxins, CDT enters host cells via endosomes. Here we show via surface plasmon resonance and electrochemical impedance spectroscopy that the cell-binding component of CDT, termed CDTb, binds and form pores in lipid bilayers in the absence of its enzymatic component, CDTa. This occurs upon lowering free Ca²⁺ ion concentration, and not by decreasing pH, as found for other binary toxins (i.e., anthrax). Cryogenic electron microscopy (CryoEM), X-ray crystallography, and

SUBMITTER: Abeyawardhane DL 

PROVIDER: S-EPMC12149301 | biostudies-literature | 2025 Jun

REPOSITORIES: biostudies-literature