Inclusion Bodies of Recombinant OmpF Porin from Yersinia Pseudotuberculosis : Properties and Structural Characterization

Mature pore-forming OmpF protein from the outer membrane of Yersinia pseudotuberculosis was expressed in Escherichia coli in the form of inclusion bodies (IBs) under different cultivation conditions. The properties and structural organization of the IBs as well as the structure of the recombinant porin (rOmpF) solubilized from the IBs were investigated using electron microscopy, dynamic light scattering, optical spectroscopy, and specific hydrophobic dyes. The size, shape, and stability of the IBs under denaturing solutions were determined. It was found that the IBs were readily soluble in SDS and more resistant to urea. Dissolution of the IBs in both denaturing agents led to formation of a heterogeneous in size population of oligomeric particles. The IBs contained an intermediate form of the rOmpF with native-like secondary structure and elements of tertiary structure, which was able to penetrate a lipid bilayer and adopt a functionally active conformation. There were no significant differences in the properties and structure between the examined IBs formed at different concentrations of the inducer (IPTG). However, the content of amyloids in the IBs increased with increasing concentration of the inducer. These results contribute to the development of new approaches for the production of active proteins from IBs, as well as biologically and functionally active IBs.