Tc toxin activation requires unfolding and refolding of a β-propeller

Gatsogiannis C, Merino F, Roderer D, Balchin D, Schubert E, Kuhlee A, Hayer-Hartl M, Raunser S. (2018). Nature 

doi: 10.1038/s41586-018-0556-6. 

Tc toxins that secrete toxic enzymes into host cells are composed of three subunits, TcA, TcB and TcC. The Raunser lab in cooperation with the Hayer-Hartl lab from the MPI of Biochemistry in Martinsried now show in atomic detail how the assembly of the three components activates the toxin.

More information here: Gatekeeper for poison capsule    
The toxin complex consists of the three components TcA (red, yellow), TcB (dark-blue) and TcC (light-blue). The poison capsule (TcB-TcC) is closed by a six-bladed propeller (grey, dark-blue) with a central hairpin structure, also called the “gatekeeper” (lock). When the poison capsule connects to the channel (yellow) of the TcA subunit, the gatekeeper turns sideways and opens the channel. The poison (green) is released.
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