In vitro trimerization of OmpF porin secreted by spheroplasts of Escherichia coli.

Abstract

It is not yet clear how bacterial outer membrane proteins reach their correct destination after they are secreted across the cytoplasmic membrane. We show here that porin OmpF is secreted into the medium as a water-soluble monomeric protein by spheroplasts of Escherichia coli. Furthermore, this monomeric porin is taken up by cell envelope preparations or purified lipopolysaccharides in the presence of 0.03% Triton X-100 and is converted correctly into the mature trimeric conformation. These results appear to reproduce a part of the physiological export and targeting steps of this protein.