Mechanism of TccC3 mediated Tc toxin intoxication. (IMAGE)
Caption
After binding of the toxin to receptors on the surface of the host cell, it is endocytosed. Structural changes in the complex trigger the opening of a cocoon which contains a toxic enzyme, which is then secreted in a unique injection mechanism via a channel into the cytoplasm of the host cell. It folds and binds to F-actin. Opening of a gate (K185 – E265) facilitates NAD+ entry. The following reaction leads to the transfer of the ADP-ribose group to actin. This modification impairs binding of actin-depolymerizing factors to F-actin which leads to actin clumping and ultimately cell death.
Credit
MPI of Molecular Physiology
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