Orientation of the monomeric porin OmpG in planar lipid bilayers.

ABSTRACT: Outer membrane protein G (OmpG) is a non-selective porin from Escherichia coli. OmpG is a monomer, which makes it unusual among porins, and suggests that it may be useful in biotechnology. In planar lipid bilayers, individual OmpG pores reconstituted by insertion from detergent exhibit pronounced asymmetry in current-voltage relationships and voltage-dependent gating. Here, this asymmetry is used to deduce the orientation of OmpG in the bilayers. We introduced two cysteines into the extracellular loops of OmpG. Cleavage of the disulfide bond formed by these residues significantly increases spontaneous gating of the pore. By adding DTT to one side of the bilayer or the other, we demonstrated that pores showing a quiet trace at negative potentials have a "trans" conformation (extracellular l

SUBMITTER: Chen M 

PROVIDER: S-EPMC3498615 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature