Structural and functional characterization of a synthetically modified OmpG.

Chemical modification of ion channels has recently attracted attention due to their potential use in stochastic sensing and neurobiology. Among the available channel templates stable β-barrel proteins have shown their potential for large scale chemical modifications due to their wide pore lumen. Ion-channel hybrids using the outer membrane protein OmpG were generated by S-alkylation with a synthetic modulator and functionally as well as structurally characterized.

On the function and structure of synthetically modified porins.

The attachment of modulators to a trimeric porin ion channel was investigated (see picture of the trimer with a crown ether modulator (orange)). The interplay of modulator and protein is essential for the conformational heterogeneity of the hybrid channel. Single-site attachment in large pores is not sufficient to change the electrophysiological characteristics of the pores-such change requires additional noncovalent interactions or second-site attachments.

Expanding the scope of protein trans-splicing to fragment ligation of an integral membrane protein: towards modulation of porin-based ion channels by chemical modification.

It's raining, it's porin: Fragment ligation of OmpF ion channels was achieved by using the split Psp-GBD Pol intein; this allowed reconstitution of active trimeric porin. In combination with cysteine modification at an internal position, the porin's conductance properties were altered.