5LKI: Cryo-em Structure Of The Tc Toxin Tcda1 In Its Pore State

Tc toxins from pathogenic bacteria use a special syringe-like mechanism to perforate the host cell membrane and inject a deadly enzyme into the host cytosol. The molecular mechanism of this unusual injection system is poorly understood. Using electron cryomicroscopy, we determined the structure of TcdA1 from Photorhabdus luminescens embedded in lipid nanodiscs. In our structure, compared with the previous structure of TcdA1 in the prepore state, the transmembrane helices rearrange in the membrane and open the initially closed pore. However, the helices do not span the complete membrane; instead, the loops connecting the helices form the rim of the funnel. Lipid head groups reach into the space between the loops and consequently stabilize the pore conformation. The linker domain is folded and packed into a pocket formed by the other domains of the toxin, thereby considerably contributing to stabilization of the pore state.
PDB ID: 5LKIDownload
MMDB ID: 142697
PDB Deposition Date: 2016/7/22
Updated in MMDB: 2016/10
Experimental Method:
electron microscopy
Resolution: 3.46  Å
Source Organism:
Similar Structures:
Biological Unit for 5LKI: pentameric; determined by author and by software (PISA)
Molecular Components in 5LKI
Label Count Molecule
Proteins (5 molecules)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB