Molecular Playground/ClyA

About this Structure

Image:ClyA-monomer2.png

Figure 1. The soluble ClyA monomer, 1QOY, rendered in PyMol.

1QOY in Figure 1 above is a monomer from the dodecameric pore-forming toxin (PFT) from Escherichia coli. It is a 34kDa protein comprised of four alpha helicies, a smaller fifth alpha helix, and a beta tongue. ClyA has been shown to form pores through a non-classical assembly pathway, excreted in oligomeric form in outer-membrane vesicles (OMV) as pre-pores. Only until ClyA reaches the target host membrane does it form the dodecameric PFT with hemolytic activity. Though its crystal structure, 2WCD, as shown in Figure 2 revealing a dodecamer, larger pores have been isolated, as well.

Image:ClyA.png Image:ClyA-protomer.png

Figure 2. The dodecameric ClyA crystal structure rendered in PyMol (left), revealing the lumen of the pore. The protomer of ClyA is on the right.

The protomer of ClyA, shown in Figure 2 on the right, reveals slight differences between the monomer and protomer. The major conformational changes between the monomer and the protomer are the positions of the N-terminal helix and the beta-tongue. As ClyA oligomerizes and forms a pore, the N-terminal helix swings to the opposite side of the molecule while the beta-tongue changes its conformation and turns into an alpha-helix that interacts with the lipid bilayer.

Research on ClyA at UMass Amherst

The Chen Lab, in collaboration with the Heuck lab, recently published a paper on ClyA assembly. Currently, we are investigating the forces that influence polymer translocation through ClyA.