Events & Seminars > Event Details

Where:

4:00 pm
Room 304, Chemistry Building

A hole on the membrane: using pore-forming proteins to attack and sense

Speaker:

Professor Min Chen
University of Massachusetts

Hosted by: Professor Linda Columbus

Pore-forming toxins (PFTs) represent the largest family of bacterial protein toxins and constitute important bacterial virulence factors. Their cytolytic function operates by introducing a large, water-filled pore into target cell membranes. We recently found out that E. coli ClyA PFT assembles into an oligomeric structure in solution in the absence of either bilayer membranes or detergents at physiological temperature. The water-soluble oligomer may represent a prepore intermediate state. Furthermore, we show that ClyA does not form transmembrane pores on E. coli lipid membranes. Since ClyA is delivered to the target host cell in an oligomeric conformation within outer membrane vesicles (OMVs), our findings support models that suggest ClyA forms a prepore oligomeric structure independently of the lipid membrane within the OMV. The proposed model for ClyA represents a non-classical pathway to attack eukaryotic host cells.

Pore-forming proteins also hold tremendous promise in biotech applications such as DNA sequencing and biosensing. We have demonstrated a monomeric β-barrel porin, OmpG, could be used as a nanopore sensing platform. OmpG is decorated with several flexible loops that move dynamically to create a distinct gating pattern when ionic current passes through the pore.  We could harness the gating characteristic of the loop’s movement in and out of the porin to distinguish between structural homologues within an antibody mixture. Our exploitation of gating noise as a molecular identifier may open new possibilities for more sophisticated sensor design.