Membrane binding and pore formation is Ca 2+ -dependent for the Clostridioides difficile binary toxin

Dinendra L Abeyawardhane; Spiridon E Sevdalis; Kaylin A Adipietro; Raquel Godoy-Ruiz; Kristen M Varney; Izza F Nawaz; Alejandro X Spittel; Richard R Rustandi; Vitalii I Silin; Amedee des Georges; Edwin Pozharski; David J Weber

doi:10.1101/2023.08.18.553786

Membrane binding and pore formation is Ca 2+ -dependent for the Clostridioides difficile binary toxin

Dinendra L Abeyawardhane, Spiridon E Sevdalis, Kaylin A Adipietro, Raquel Godoy-Ruiz, Kristen M Varney, Izza F Nawaz, Alejandro X Spittel, Richard R Rustandi, Vitalii I Silin, Amedee des Georges, Edwin Pozharski, David J Weber

Molecular Pathobiology

Research output: Contribution to journal › Article

Abstract

The C. difficile binary toxin (CDT) enters host cells via endosomal delivery like many other 'AB'-type binary toxins. In this study, the cell-binding component of CDT, termed CDTb, was found to bind and form pores in lipid bilayers upon depleting free Ca 2+ ion concentrations, and not by lowering pH, as found for other binary toxins (i.e., anthrax). Cryoelectron microscopy, nuclear magnetic resonance spectroscopy, surface plasmon resonance, electrochemical impedance spectroscopy, CDT toxicity studies, and site directed mutagenesis show that dissociation of Ca 2+ from a single site in receptor binding domain 1 (RBD1) of CDTb is consistent with a molecular mechanism in which Ca 2+ dissociation from RBD1 induces a "trigger" via conformational exchange that enables CDTb to bind and form pores in endosomal membrane bilayers as free Ca 2+ concentrations decrease during CDT endosomal delivery.

Original language	English (US)
Journal	bioRxiv
DOIs	https://doi.org/10.1101/2023.08.18.553786
State	Published - Sep 21 2023

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@article{13d37722bf974d84b0309af149d8a637,

title = "Membrane binding and pore formation is Ca 2+ -dependent for the Clostridioides difficile binary toxin",

abstract = "The C. difficile binary toxin (CDT) enters host cells via endosomal delivery like many other 'AB'-type binary toxins. In this study, the cell-binding component of CDT, termed CDTb, was found to bind and form pores in lipid bilayers upon depleting free Ca 2+ ion concentrations, and not by lowering pH, as found for other binary toxins (i.e., anthrax). Cryoelectron microscopy, nuclear magnetic resonance spectroscopy, surface plasmon resonance, electrochemical impedance spectroscopy, CDT toxicity studies, and site directed mutagenesis show that dissociation of Ca 2+ from a single site in receptor binding domain 1 (RBD1) of CDTb is consistent with a molecular mechanism in which Ca 2+ dissociation from RBD1 induces a {"}trigger{"} via conformational exchange that enables CDTb to bind and form pores in endosomal membrane bilayers as free Ca 2+ concentrations decrease during CDT endosomal delivery.",

author = "Abeyawardhane, {Dinendra L} and Sevdalis, {Spiridon E} and Adipietro, {Kaylin A} and Raquel Godoy-Ruiz and Varney, {Kristen M} and Nawaz, {Izza F} and Spittel, {Alejandro X} and Rustandi, {Richard R} and Silin, {Vitalii I} and {des Georges}, Amedee and Edwin Pozharski and Weber, {David J}",

year = "2023",

month = sep,

day = "21",

doi = "10.1101/2023.08.18.553786",

language = "English (US)",

journal = "bioRxiv",

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TY - JOUR

T1 - Membrane binding and pore formation is Ca 2+ -dependent for the Clostridioides difficile binary toxin

AU - Abeyawardhane, Dinendra L

AU - Sevdalis, Spiridon E

AU - Adipietro, Kaylin A

AU - Godoy-Ruiz, Raquel

AU - Varney, Kristen M

AU - Nawaz, Izza F

AU - Spittel, Alejandro X

AU - Rustandi, Richard R

AU - Silin, Vitalii I

AU - des Georges, Amedee

AU - Pozharski, Edwin

AU - Weber, David J

PY - 2023/9/21

Y1 - 2023/9/21

N2 - The C. difficile binary toxin (CDT) enters host cells via endosomal delivery like many other 'AB'-type binary toxins. In this study, the cell-binding component of CDT, termed CDTb, was found to bind and form pores in lipid bilayers upon depleting free Ca 2+ ion concentrations, and not by lowering pH, as found for other binary toxins (i.e., anthrax). Cryoelectron microscopy, nuclear magnetic resonance spectroscopy, surface plasmon resonance, electrochemical impedance spectroscopy, CDT toxicity studies, and site directed mutagenesis show that dissociation of Ca 2+ from a single site in receptor binding domain 1 (RBD1) of CDTb is consistent with a molecular mechanism in which Ca 2+ dissociation from RBD1 induces a "trigger" via conformational exchange that enables CDTb to bind and form pores in endosomal membrane bilayers as free Ca 2+ concentrations decrease during CDT endosomal delivery.

AB - The C. difficile binary toxin (CDT) enters host cells via endosomal delivery like many other 'AB'-type binary toxins. In this study, the cell-binding component of CDT, termed CDTb, was found to bind and form pores in lipid bilayers upon depleting free Ca 2+ ion concentrations, and not by lowering pH, as found for other binary toxins (i.e., anthrax). Cryoelectron microscopy, nuclear magnetic resonance spectroscopy, surface plasmon resonance, electrochemical impedance spectroscopy, CDT toxicity studies, and site directed mutagenesis show that dissociation of Ca 2+ from a single site in receptor binding domain 1 (RBD1) of CDTb is consistent with a molecular mechanism in which Ca 2+ dissociation from RBD1 induces a "trigger" via conformational exchange that enables CDTb to bind and form pores in endosomal membrane bilayers as free Ca 2+ concentrations decrease during CDT endosomal delivery.

U2 - 10.1101/2023.08.18.553786

DO - 10.1101/2023.08.18.553786

M3 - Article

C2 - 37645845

JO - bioRxiv

JF - bioRxiv

ER -

Membrane binding and pore formation is Ca 2+ -dependent for the Clostridioides difficile binary toxin

Abstract

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